WorldWideScience

Sample records for dual-source hybrid heat

  1. Dual source heat pump

    Science.gov (United States)

    Ecker, Amir L.; Pietsch, Joseph A.

    1982-01-01

    What is disclosed is a heat pump apparatus for conditioning a fluid characterized by a fluid handler and path for circulating the fluid in heat exchange relationship with a refrigerant fluid; at least two refrigerant heat exchangers, one for effecting heat exchange with the fluid and a second for effecting heat exchange between refrigerant and a heat exchange fluid and the ambient air; a compressor for efficiently compressing the refrigerant; at least one throttling valve for throttling liquid refrigerant; a refrigerant circuit; refrigerant; a source of heat exchange fluid; heat exchange fluid circulating device and heat exchange fluid circuit for circulating the heat exchange fluid in heat exchange relationship with the refrigerant; and valves or switches for selecting the heat exchangers and direction of flow of the refrigerant therethrough for selecting a particular mode of operation. The heat exchange fluid provides energy for defrosting the second heat exchanger when operating in the air source mode and also provides a alternate source of heat.

  2. Simulation analysis on dynamic performance of a combined solar/air dual source heat pump water heater

    International Nuclear Information System (INIS)

    Deng, Weishi; Yu, Jianlin

    2016-01-01

    Highlights: • A modified direct expansion solar-assisted heat pump water heater is investigated. • An additional air source evaporator is used in parallel way in the M-DX-SHPWH system. • The M-DX-SHPWH system displays a higher performance at the low solar radiation. • Effects of solar radiation and air temperature on the performance are discussed. - Abstract: This paper investigated a combined solar/air dual source heat pump water heater system for domestic water heating application. In the dual source system, an additional air source evaporator is introduced in parallel way based on a conventional direct expansion solar-assisted heat pump water heaters (DX-SHPWH) system, which can improve the performance of the DX-SHPWH system at a low solar radiation. In the present study, a dynamic mathematical model based on zoned lump parameter approach is developed to simulate the performance of the system (i.e. a modified DX-SHPWH (M-DX-SHPWH) system). Using the model, the performance of M-DX-SHPWH system is evaluated and then compared with that of the conventional DX-SHPWH system. The simulation results show the M-DX-SHPWH system has a better performance than that of the conventional DX-SHPWH system. At a low solar radiation of 100 W/m"2, the heating time of the M-DX-SHPWH decreases by 19.8% compared to the DX-SHPWH when water temperature reaches 55 °C. Meanwhile, the COP on average increases by 14.1%. In addition, the refrigerant mass flow rate distribution in the air source evaporator and the solar collector of the system, the allocation between the air source evaporator and the solar collector areas and effects of solar radiation and ambient air temperature on the system performance are discussed.

  3. A novel PV/T-air dual source heat pump water heater system: Dynamic simulation and performance characterization

    International Nuclear Information System (INIS)

    Cai, Jingyong; Ji, Jie; Wang, Yunyun; Zhou, Fan; Yu, Bendong

    2017-01-01

    Highlights: • The PV/T evaporator and air source evaporator connect in parallel and operate simultaneously. • A dynamic model is developed to simulate the behavior of the system. • The thermal and electrical characteristics of the PV/T evaporator are evaluated. • The contribution of the air source evaporator and PV/T evaporator has been discussed. - Abstract: To enable the heat pump water heater maintain efficient operation under diverse circumstances, a novel PV/T-air dual source heat pump water heater (PV/T-AHPWH) has been proposed in this study. In the PV/T-AHPWH system, a PV/T evaporator and an air source evaporator connect in parallel and operate simultaneously to recover energy from both solar energy and environment. A dynamic model is presented to simulate the behavior of the PV/T-AHPWH system. On this basis, the influences of solar irradiation, ambient temperature and packing factor have been discussed, and the contributions of air source evaporator and PV/T evaporator are evaluated. The results reveal that the system can obtain efficient operation with the average COP above 2.0 under the ambient temperature of 10 °C and solar irradiation of 100 W/m 2 . The PV/T evaporator can compensate for the performance degradation of the air source evaporator caused by the increasing condensing temperature. As the evaporating capacity in PV/T evaporator remains at relatively low level under low irradiation, the air source evaporator can play the main role of recovering heat. Comparing the performance of dual source heat pump system employing PV/T collector with that utilizing normal solar thermal collector, the system utilizing PV/T evaporator is more efficient in energy saving and performance improvement.

  4. Determining of the optimal design of a closed loop solar dual source heat pump system coupled with a residential building application

    International Nuclear Information System (INIS)

    Chargui, Ridha; Awani, Sami

    2017-01-01

    Graphical abstract: Operation of the system in heating mode. - Highlights: • We examine the control function in the level of heat pump and collector. • We examine the temporal evolution of the temperature and energy in the all components of the system. • A better system with a significant energy saving was achieved. • The system gives good results in all operating states. - Abstract: This work highlights the results on the coupling of a flat plate collector coupled with a dual source heat pump system and a heat exchanger for building application. The novelty point of this work is to integrate a heat exchanger in the floor and in the interstitial space of the residential house roof in order to minimize the consumed electric power. This technology defining the operational state of the system has been developed and adapted in the present investigation by adopting the Tunisian climate. The dimensioning of this installation for different component makes it possible to operate the hot water heating systems ecologically. Hence, our objective is to ameliorate the performance of the system using the solar radiation converted to the thermal energy in the level of the flat plate collector and the heat pump. A several experimental data have been added for realizing a numerical model based on TRNSYS software. From this point of view, a numerical model was improved in building application using a 150 m 2 as surface area of the building which consists of two floor zones. The dual source heat pump was coupled with a ground heat exchanger (GHE) with 0.2 m of depth. The distance between two consecutive tubes is 0.3 m and the surface area of the solar collector is 8 m 2 . The simulation results have been obtained for 48 h operation in January and all inputs data of the system have been predicted during 48 h and 6 months of heating in Tunisia. It was demonstrated that the COP of the dual source heat pump was enhanced with the increase of the solar radiation during the typical

  5. Dual source CT imaging

    International Nuclear Information System (INIS)

    Seidensticker, Peter R.; Hofmann, Lars K.

    2008-01-01

    The introduction of Dual Source Computed Tomography (DSCT) in 2005 was an evolutionary leap in the field of CT imaging. Two x-ray sources operated simultaneously enable heart-rate independent temporal resolution and routine spiral dual energy imaging. The precise delivery of contrast media is a critical part of the contrast-enhanced CT procedure. This book provides an introduction to DSCT technology and to the basics of contrast media administration followed by 25 in-depth clinical scan and contrast media injection protocols. All were developed in consensus by selected physicians on the Dual Source CT Expert Panel. Each protocol is complemented by individual considerations, tricks and pitfalls, and by clinical examples from several of the world's best radiologists and cardiologists. This extensive CME-accredited manual is intended to help readers to achieve consistently high image quality, optimal patient care, and a solid starting point for the development of their own unique protocols. (orig.)

  6. 太阳能一空气双热源复合热泵系统性能研究%Studying of the System Performance of the Solar - air Dual - source Heat Pump

    Institute of Scientific and Technical Information of China (English)

    张超; 赵晓丹; 周光辉

    2011-01-01

    太阳能—空气双热源复合热泵技术能有效解决空气源热泵室外温度低时蒸发器易结霜、系统性能降低的缺点.本文在课题组前期研究的基础上,针对一种新型的太阳能—空气双热源复合热泵系统,采用分布参数法建立了系统的数学模型.利用数学模拟的方法对单一空气源热泵系统和太阳能—空气双热源复合热泵系统在三种不同工况下的制热量和COP进行了模拟,并对模拟结果进行了对比分析.%The problems such as the easily frosting of the evaporator and the poor system performance in low outdoor temperature can be effectively solved with the solar-air dual-source heat pump technology. In this paper, based on the previous working of the research group, the steady distributed parameter method has been adopted to establish the mathematical model of a new solar-air dual-source heat pump system. The system performance of the single air source heat pump system and the solar-air dual-source heat pump system in three operation conditions have been studied with the mathematical simulation method, and the simulated results have been analyzed.

  7. Hybrid Heat Capacity - Moving Slab Laser Concept

    International Nuclear Information System (INIS)

    Stappaerts, E A

    2002-01-01

    A hybrid configuration of a heat capacity laser (HCL) and a moving slab laser (MSL) has been studied. Multiple volumes of solid-state laser material are sequentially diode-pumped and their energy extracted. When a volume reaches a maximum temperature after a ''sub-magazine depth'', it is moved out of the pumping region into a cooling region, and a new volume is introduced. The total magazine depth equals the submagazine depth times the number of volumes. The design parameters are chosen to provide high duty factor operation, resulting in effective use of the diode arrays. The concept significantly reduces diode array cost over conventional heat capacity lasers, and it is considered enabling for many potential applications. A conceptual design study of the hybrid configuration has been carried out. Three concepts were evaluated using CAD tools. The concepts are described and their relative merits discussed. Because of reduced disk size and diode cost, the hybrid concept may allow scaling to average powers on the order of 0.5 MW/module

  8. Lower hybrid heating experiments in tokamaks: an overview

    International Nuclear Information System (INIS)

    Porkolab, M.

    1985-10-01

    Lower hybrid wave propagation theory relevant to heating fusion grade plasmas (tokamaks) is reviewed. A brief discussion of accessibility, absorption, and toroidal ray propagation is given. The main part of the paper reviews recent results in heating experiments on tokamaks. Both electron and ion heating regimes will be discussed. The prospects of heating to high temperatures in reactor grade plasmas will be evaluated

  9. Technical principles of dual source CT

    International Nuclear Information System (INIS)

    Petersilka, Martin; Bruder, Herbert; Krauss, Bernhard; Stierstorfer, Karl; Flohr, Thomas G.

    2008-01-01

    During the past years, multi-detector row CT (MDCT) has evolved into clinical practice with a rapid increase of the number of detector slices. Today's 64 slice CT systems allow whole-body examinations with sub-millimeter resolution in short scan times. As an alternative to adding even more detector slices, we describe the system concept and design of a CT scanner with two X-ray tubes and two detectors (mounted on a CT gantry with a mechanical offset of 90 deg.) that has the potential to overcome limitations of conventional MDCT systems, such as temporal resolution for cardiac imaging. A dual source CT (DSCT) scanner provides temporal resolution equivalent to a quarter of the gantry rotation time, independent of the patient's heart rate (83 ms at 0.33 s rotation time). In addition to the benefits for cardiac scanning, it allows to go beyond conventional CT imaging by obtaining dual energy information if the two tubes are operated at different voltages. Furthermore, we discuss how both acquisition systems can be used to add the power reserve of two X-ray tubes for long scan ranges and obese patients. Finally, future advances of DSCT are highlighted

  10. Heat transfer characteristics and operation limit of pressurized hybrid heat pipe for small modular reactors

    International Nuclear Information System (INIS)

    Kim, Kyung Mo; Bang, In Cheol

    2017-01-01

    Highlights: • Thermal performances and operation limits of hybrid heat pipe were experimentally studied. • Models for predicting the operation limit of the hybrid heat pipe was developed. • Non-condensable gas affected heat transfer characteristics of the hybrid heat pipe. - Abstract: In this paper, a hybrid heat pipe is proposed for use in advanced nuclear power plants as a passive heat transfer device. The hybrid heat pipe combines the functions of a heat pipe and a control rod to simultaneously remove the decay heat generated from the core and shutdown the reactor under accident conditions. Thus, the hybrid heat pipe contains a neutron absorber in the evaporator section, which corresponds to the core of the reactor pressure vessel. The presence of the neutron absorber material leads to differences in the heated diameter and hydraulic diameter of the heat pipe. The cross-sectional areas of the vapor paths through the evaporator, adiabatic, and condenser sections are also different. The hybrid heat pipe must operate in a high-temperature, high-pressure environment to remove the decay heat. In other words, the operating pressure must be higher than those of the commercially available thermosyphons. Hence, the thermal performances, including operation limit of the hybrid heat pipe, were experimentally studied in the operating pressure range of 0.2–20 bar. The operating pressure of the hybrid heat pipe was controlled by charging the non-condensable gas which is unused method to achieve the high saturation pressure in conventional thermosyphons. The effect of operating pressure on evaporation heat transfer was negligible, while condensation heat transfer was affected by the amount of non-condensable gas in the test section. The operation limit of the hybrid heat pipe increased with the operating pressure. Maximum heat removal capacity of the hybrid heat pipe was up to 6 kW which is meaningful value as a passive decay heat removal device in the nuclear power

  11. Plasma heating and hot ion sustaining in mirror based hybrids

    International Nuclear Information System (INIS)

    Moiseenko, V. E.; Ågren, O.

    2012-01-01

    Possibilities of plasma heating and sloshing ion sustaining in mirror based hybrids are briefly reviewed. Sloshing ions, i.e. energetic ions with a velocity distribution concentrated to a certain pitch-angle, play an important role in plasma confinement and generation of fusion neutrons in mirror machines. Neutral beam injection (NBI) is first discussed as a method to generate sloshing ions. Numerical results of NBI modeling for a stellarator-mirror hybrid are analyzed. The sloshing ions could alternatively be sustained by RF heating. Fast wave heating schemes, i.e. magnetic beach, minority and second harmonic heating, are addressed and their similarities and differences are described. Characteristic features of wave propagation in mirror hybrid devices including both fundamental harmonic minority and second harmonic heating are examined. Minority heating is efficient for a wide range of minority concentration and plasma densities; it allows one to place the antenna aside from the hot ion location. A simple-design strap antenna suitable for this has good performance. However, this scenario is appropriate only for light minority ions. The second harmonic heating can be applied for the heavy ion component. Arrangements are similar for minority and second harmonic heating. The efficiency of second harmonic heating is influenced by a weaker wave damping than for minority heating. Numerical calculations show that in a hybrid reactor scaled mirror machine the deuterium sloshing ions could be heated within the minority heating scheme, while the tritium ions could be sustained by second harmonic heating.

  12. Automated Hybrid Microwave Heating for Lunar Surface Solidification, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR project addresses the need for a system that will provide automated lunar surface stabilization via hybrid microwave heating. Surface stabilization is...

  13. 基于太阳能光伏光热组件的双热源热泵机组的实验研究%Experimental Research of Dual-source Heat Pump Unit Based on Solar Photovoltaic and Photothermal Component

    Institute of Scientific and Technical Information of China (English)

    陈剑波; 孙坤; 聂琳杰; 陈雷田

    2015-01-01

    本文基于太阳能光伏光热一体化系统,设计出应用太阳能光伏光热及空气源的双热源热泵机组。使热泵与太阳能光伏光热组件结合组成太阳能热泵系统,利用太阳能光伏光热组件( PV/T)内循环水及空气源的能量制取生活热水,同时降低太阳能光伏光热组件内循环水的温度,从而降低太阳能光伏板的温度。通过实验测得机组在水冷蒸发侧进水温度20℃,热水出水温度50℃的额定工况下,制冷量为2.855 kW,制热量为3.594 kW,COP为3.6。机组在水-水工况及水-风工况下运行的节能性研究结果表明,相对于单一空气源热泵,双热源热泵机组在满足家庭用生活热水需求的前提下,利用热泵技术回收太阳能光伏光热的热量制取生活热水节能性显著。%Based on the solar photovoltaic-thermal integrated system, we designed a dual-source, i. e. , solar photovoltaic-thermal and air source, heat pump unit. The unit becomes solar assisted heat pump system when combined with solar photovoltaic thermal unit, which produces domestic hot water by air source and circulating water in the solar photovoltaic solar-thermal components ( PV/T) and reduces circulating water temperature and solar photovoltaic panel temperature. We drew the conclusion by experiment that when the inflow water temperature is 20 ℃ on the evaporation side and the outflow hot water temperature is 50 ℃ under the rated conditions, the unit capacity is 2. 855 kW for refrigeration and 3. 594 kW for heating, and the COP is 3. 6. When the unit operates in the water-water condition and wa-ter-air condition, the experiment result shows the dual-source heat pump unit has remarkable energy-saving compared with single air source heat pump when the photovoltaic-thermal solar heat is used for domestic hot water.

  14. Rate Control in Dual Source Evaporation

    NARCIS (Netherlands)

    Wielinga, T.; Gruisinga, W.; Leeuwis, H.; Lodder, J.C.; van Weers, J.F.; Wilmans, J.C.

    1980-01-01

    Two-component thin films are deposited in a high-vacuum system from two close sources, heated by an electron beam which is deflected between them. By using quartz-crystal monitors the evaporation rates are measured seperately, which is usually considered to be problematical. One rate signal is used

  15. The Ion Cyclotron, Lower Hybrid, and Alfven Wave Heating Methods

    International Nuclear Information System (INIS)

    Koch, R.

    2004-01-01

    This lecture covers the practical features and experimental results of the three heating methods. The emphasis is on ion cyclotron heating. First, we briefly come back to the main non-collisional heating mechanisms and to the particular features of the quasilinear coefficient in the ion cyclotron range of frequencies (ICRF). The specific case of the ion-ion hybrid resonance is treated, as well as the polarisation issue and minority heating scheme. The various ICRF scenarios are reviewed. The experimental applications of ion cyclotron resonance heating (ICRH) systems are outlined. Then, the lower hybrid and Alfven wave heating and current drive experimental results are covered more briefly. Where applicable, the prospects for ITER are commented

  16. Hybrid Ventilation with Innovative Heat Recovery—A System Analysis

    Directory of Open Access Journals (Sweden)

    Bengt Hellström

    2013-02-01

    Full Text Available One of the most important factors when low energy houses are built is to have good heat recovery on the ventilation system. However, standard ventilation units use a considerable amount of electricity. This article discusses the consequences on a system level of using hybrid ventilation with heat recovery. The simulation program TRNSYS was used in order to investigate a ventilation system with heat recovery. The system also includes a ground source storage and waste water heat recovery system. The result of the analysis shows that the annual energy gain from ground source storage is limited. However, this is partly a consequence of the fact that the well functioning hybrid ventilation system leaves little room for improvements. The analysis shows that the hybrid ventilation system has potential to be an attractive solution for low energy buildings with a very low need for electrical energy.

  17. Performance analysis of hybrid district heating system

    DEFF Research Database (Denmark)

    Mikulandric, Robert; Krajačić, Goran; Khavin, Gennadii

    2013-01-01

    District heating system could contribute to more efficient heat generation through cogeneration power plants or waste heat utilization facilities and to increase of renewable energy sources share in total energy consumption. In the most developed EU countries, renewable energy sources have been...... as problems related to transportation, storage and environmental impacts of biomass and waste utilisation. Implementation of heat storages in district heating systems could contribute to integration of intermittent energy sources. Hybridisation of heat production facility combines two or more different energy...... more extensively used in district heating systems either separately or as a supplement to traditional fossil fuels in order to achieve national energy policy objectives. However, they are still facing problems such as high intermittences, high energy production costs and low load factors as well...

  18. Performance Analysis of a Hybrid District Heating System

    DEFF Research Database (Denmark)

    Mikulandric, Robert; Krajačić, Goran; Duic, Neven

    2015-01-01

    Hybridisation of district heating systems can contribute to more efficient heat generation through cogeneration power plants or through the share increase of renewable energy sources in total energy consumption while reducing negative aspects of particular energy source utilisation. In this work......, the performance of a hybrid district energy system for a small town in Croatia has been analysed. Mathematical model for process analysis and optimisation algorithm for optimal system configuration has been developed and described. The main goal of the system optimisation is to reduce heat production costs....... Several energy sources for heat production have been considered in 8 different simulation cases. Simulation results show that the heat production costs could be reduced with introduction of different energy systems into an existing district heating system. Renewable energy based district heating systems...

  19. Drive Current Enhancement in TFET by Dual Source Region

    Directory of Open Access Journals (Sweden)

    Zhi Jiang

    2015-01-01

    Full Text Available This paper presents tunneling field-effect transistor (TFET with dual source regions. It explores the physics of drive current enhancement. The novel approach of dual source provides an effective technique for enhancing the drive current. It is found that this structure can offer four tunneling junctions by increasing a source region. Meanwhile, the dual source structure does not influence the excellent features of threshold slope (SS of TFET. The number of the electrons and holes would be doubled by going through the tunneling junctions on the original basis. The overlap length of gate-source is also studied. The dependence of gate-drain capacitance Cgd and gate-source capacitance Cgs on gate-to-source voltage Vgs and drain-to-source voltage Vds was further investigated. There are simulation setups and methodology used for the dual source TFET (DS-TFET assessment, including delay time, total energy per operation, and energy-delay product. It is confirmed that the proposed TFET has strong potentials for VLSI.

  20. Hybrid simulation of electron cyclotron resonance heating

    Energy Technology Data Exchange (ETDEWEB)

    Ropponen, T. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FI-40014 (Finland)], E-mail: tommi.ropponen@phys.jyu.fi; Tarvainen, O. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Suominen, P. [CERN Geneve 23, CH-1211 (Switzerland); Koponen, T.K. [Department of Physics, University of Jyvaeskylae, Nanoscience Center, P.O. Box 35, FI-40014 (Finland); Kalvas, T.; Koivisto, H. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FI-40014 (Finland)

    2008-03-11

    Electron Cyclotron Resonance (ECR) heating is a fundamentally important aspect in understanding the physics of Electron Cyclotron Resonance Ion Sources (ECRIS). Absorption of the radio frequency (RF) microwave power by electron heating in the resonance zone depends on many parameters including frequency and electric field strength of the microwave, magnetic field structure and electron and ion density profiles. ECR absorption has been studied in the past by e.g. modelling electric field behaviour in the resonance zone and its near proximity. This paper introduces a new ECR heating code that implements damping of the microwave power in the vicinity of the resonance zone, utilizes electron density profiles and uses right hand circularly polarized (RHCP) electromagnetic waves to simulate electron heating in ECRIS plasma.

  1. Hybrid district heating system with heat supply from nuclear source

    International Nuclear Information System (INIS)

    Havelka, Z.; Petrovsky, I.

    1987-01-01

    Several designs are described of heat supply from large remote power sources (e.g., WWER-1000 nuclear power plants with a 1000 MW turbine) to localities where mainly steam distribution networks have been built but only some or none networks for hot water distribution. The benefits of the designs stem from the fact that they do not require the conversion of the local steam distribution system to a hot water system. They are based on heat supply from the nuclear power plant to the consumer area in hot water of a temperature of 150 degC to 200 degC. Part of the hot water heat will be used for the production of low-pressure steam which will be compressed using heat pumps (steam compressors) to achieve the desired steam distribution network specifications. Water of lower temperature can be used in the hot water network. The hot water feeder forms an automatic pressure safety barrier in heat supply of heating or technological steam from a nuclear installation. (Z.M.). 5 figs., 9 refs

  2. Lower hybrid heating system for an ignition tokamak

    International Nuclear Information System (INIS)

    Brooks, J.; Harkness, S.; Jung, J.; Misra, B.; Moretti, A.; Norem, J.; Stevens, H.

    1978-01-01

    We have attempted to design a complete Lower Hybrid Resonance Heating System (LHRH) that could be used for TFTR, TNS, EPR, or a reactor. In addition to plasma physics constraints, we have considered those imposed by neutron radiation, surface heating of waveguides, sputtering, multipactoring, vacuum systems, materials, window design, engineering, maintenance and assembly. The system uses a Lallia--Brambilla grill which is fed by a number of waveguides entering the reactor by means of a labyrinth

  3. Electron and ion heat transport with lower hybrid current drive and neutral beam injection heating in ASDEX

    International Nuclear Information System (INIS)

    Soeldner, F.X.; Pereverzev, G.V.; Bartiromo, R.; Fahrbach, H.U.; Leuterer, F.; Murmann, H.D.; Staebler, A.; Steuer, K.H.

    1993-01-01

    Transport code calculations were made for experiments with the combined operation of lower hybrid current drive and heating and of neutral beam injection heating on ASDEX. Peaking or flattening of the electron temperature profile are mainly explained by modifications of the MHD induced electron heat transport. They originate from current profile changes due to lower hybrid and neutral beam current drive and to contributions from the bootstrap current. Ion heat transport cannot be described by one single model for all heating scenarios. The ion heat conductivity is reduced during lower hybrid heated phases with respect to Ohmic and neutral beam heating. (author). 13 refs, 5 figs

  4. Hybrid Heat Pipes for Lunar and Martian Surface and High Heat Flux Space Applications

    Science.gov (United States)

    Ababneh, Mohammed T.; Tarau, Calin; Anderson, William G.; Farmer, Jeffery T.; Alvarez-Hernandez, Angel R.

    2016-01-01

    Novel hybrid wick heat pipes are developed to operate against gravity on planetary surfaces, operate in space carrying power over long distances and act as thermosyphons on the planetary surface for Lunar and Martian landers and rovers. These hybrid heat pipes will be capable of operating at the higher heat flux requirements expected in NASA's future spacecraft and on the next generation of polar rovers and equatorial landers. In addition, the sintered evaporator wicks mitigate the start-up problems in vertical gravity aided heat pipes because of large number of nucleation sites in wicks which will allow easy boiling initiation. ACT, NASA Marshall Space Flight Center, and NASA Johnson Space Center, are working together on the Advanced Passive Thermal experiment (APTx) to test and validate the operation of a hybrid wick VCHP with warm reservoir and HiK"TM" plates in microgravity environment on the ISS.

  5. Affordable Hybrid Heat Pump Clothes Dryer

    Energy Technology Data Exchange (ETDEWEB)

    TeGrotenhuis, Ward E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Butterfield, Andrew [Jabil, St. Petersburg, FL (United States); Caldwell, Dustin D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Crook, Alexander [Jabil, St. Petersburg, FL (United States)

    2016-06-30

    This project was successful in demonstrating the feasibility of a step change in residential clothes dryer energy efficiency by demonstrating heat pump technology capable of 50% energy savings over conventional standard-size electric dryers with comparable drying times. A prototype system was designed from off-the-shelf components that can meet the project’s efficiency goals and are affordable. An experimental prototype system was built based on the design that reached 50% energy savings. Improvements have been identified that will reduce drying times of over 60 minutes to reach the goal of 40 minutes. Nevertheless, the prototype represents a step change in efficiency over heat pump dryers recently introduced to the U.S. market, with 30% improvement in energy efficiency at comparable drying times.

  6. Lower hybrid heating experiment in JFT-2 tokamak

    International Nuclear Information System (INIS)

    Uchara, K.; Nagashima, T.

    1982-01-01

    Lower hybrid heating experiments in JFT-2 are reviewed. Good maintenance and controlling of the coupling structure are very important in the injection of RF power before heating experiments. Accessibility of waves and the existence of the mode conversion region are necessary for ion heating in the main plasma. Parametric instabilities which may bring undesirable power deposition are suppressed by enough electron heating in the boundary region. Optimizing the Nsub(z) spectrum and the improvement of the plasma confinement may lead the electron heating in the high density region. Current generation by use of quasi-linear Landau damping is confirmed and is suggested to bring the improvement of plasma confinement. High power and long pulse klystrons may be expected to open a frontier toward a stational reactor plasma in tokamaks. (author)

  7. Coaxial antenna for lower hybrid heating

    International Nuclear Information System (INIS)

    Le Gardeur, R.J.

    1981-02-01

    A coaxial antenna for the heating of toroidal plasmas has been conceived and constructed. Being wholly metallic (stainless steel), the several coaxial ceramic passages assuring the transit of the H.F. energy into vacuum being situated far from the plasma, the use of such antennas can be envisaged in next generation machines where the environment is particularily severe. The coaxial design (having a lower internal impedance than a wave guide) reduces the electric fields present in the antenna-plasma interface, assuring, at the same time, a spatial uniformity of the fields making possible a substantial reduction in the transmitted power density. The main technological advantages (with respect to a wave guide grill structure) are: (a) simplification of the construction especially in multi-channel systems (b) quasi-elimination of the problems associated with the ceramic windows transmitting the H.F. energy (c) absence of a low frequency cut-off making possible to place launching structures in vertical chimneys where space is limited (d) an eventual reduction of certain phenomena inherent to this type of heating such as particle acceleration, space charge separation, pondemotive forces etc

  8. A state-of-the-art review on hybrid heat pipe latent heat storage systems

    International Nuclear Information System (INIS)

    Naghavi, M.S.; Ong, K.S.; Mehrali, M.; Badruddin, I.A.; Metselaar, H.S.C.

    2015-01-01

    The main advantage of latent heat thermal energy storage systems is the capability to store a large quantity of thermal energy in an isothermal process by changing phase from solid to liquid, while the most important weakness of these systems is low thermal conductivity that leads to unsuitable charging/discharging rates. Heat pipes are used in many applications – as one of the most efficient heat exchanger devices – to amplify the charging/discharging processes rate and are used to transfer heat from a source to the storage or from the storage to a sink. This review presents and critically discusses previous investigations and analysis on the incorporation of heat pipe devices into latent heat thermal energy storage with heat pipe devices. This paper categorizes different applications and configurations such as low/high temperature solar, heat exchanger and cooling systems, analytical approaches and effective parameters on the performance of hybrid HP–LHTES systems.

  9. Hybrid fuzzy logic control of laser surface heat treatments

    International Nuclear Information System (INIS)

    Perez, Jose Antonio; Ocana, Jose Luis; Molpeceres, Carlos

    2007-01-01

    This paper presents an advanced hybrid fuzzy logic control system for laser surface heat treatments, which allows to increase significantly the uniformity and final quality of the obtained product, reducing the rejection rate and increasing the productivity and efficiency of the treatment. Basically, the proposed hybrid control structure combines a fuzzy logic controller, with a pure integral action, both fully decoupled, improving the performances of the process with a reasonable design cost, since the system nonlinearities are fully compensated by the fuzzy component of the controller, while the integral action contributes to eliminate the steady-state error

  10. Development of a hybrid chemical/mechanical heat pump

    Science.gov (United States)

    Grzyll, Lawrence R.; Silvestri, John J.; Scaringe, Robert P.

    1991-01-01

    The authors present the current development status of a hybrid chemical/mechanical heat pump for low-lift applications. The heat pump provides electronics cooling by evaporating a pure refrigerant from an absorbent/refrigerant mixture in a generator/cold plate. The current development focused on evaluation of absorbent/refrigerant pairs, corrosion testing, pump and compressor design, and electronic cold plate design. Two cycle configurations were considered. The first configuration utilized a standard mechanical compressor and pump. The second cycle configuration investigated pumps and compressors with non-moving parts. An innovative generator/cold plate design is also presented. The development to date shows that this cycle has about the same performance as standard vapor compression heat pumps with standard refrigerants but may have some performance and reliability advantages over vapor compression heat pumps.

  11. Review of lower hybrid wave heating and current drive

    International Nuclear Information System (INIS)

    Gormezano, C.

    1986-01-01

    Interaction of Lower Hybrid waves and plasmas is a very versatile method which has proven to be effective in a large range of applications: bulk ion heating, bulk electron heating, non inductive current drive. If the ratio between the mean velocity of HF induced fast particles and the thermal velocity of the bulk population is relatively small, effective bulk ion heating or bulk electron heating can occur via collisional transfer. If the above ratio is too large, fast ions, which have mainly a perpendicular energy, are poorly confined. Moreover they can be harmful for the discharge (impurities, etc...) since they are lost on the walls. In contrast, HF induced fast electrons gain essentially a parallel momentum from the wave. If unidirectional waves are launched, the dissymetry in electron distribution result in the obtention of an effective non inductive current

  12. Simulation of Hybrid Photovoltaic Solar Assisted Loop Heat Pipe/Heat Pump System

    Directory of Open Access Journals (Sweden)

    Nannan Dai

    2017-02-01

    Full Text Available A hybrid photovoltaic solar assisted loop heat pipe/heat pump (PV-SALHP/HP water heater system has been developed and numerically studied. The system is the combination of loop heat pipe (LHP mode and heat pump (HP mode, and the two modes can be run separately or compositely according to the weather conditions. The performances of independent heat pump (HP mode and hybrid loop heat pipe/heat pump (LHP/HP mode were simulated and compared. Simulation results showed that on typical sunny days in spring or autumn, using LHP/HP mode could save 40.6% power consumption than HP mode. In addition, the optimal switchover from LHP mode to HP mode was analyzed in different weather conditions for energy saving and the all-year round operating performances of the system were also simulated. The simulation results showed that hybrid LHP/HP mode should be utilized to save electricity on sunny days from March to November and the system can rely on LHP mode alone without any power consumption in July and August. When solar radiation and ambient temperature are low in winter, HP mode should be used

  13. HYBRID INDIRECT SOLAR COOKER WITH LATENT HEAT STORAGE

    OpenAIRE

    Benazeer Hassan K. Ibrahim *, Victor Jose

    2016-01-01

    Solar cooking is the simplest, safest, most convenient way to cook food without consuming fuels or heating up the kitchen. All the conventional solar cooker designs have the disadvantage of inability to cook during off-shine and night hours.This disadvantage can be eliminated if the solar cooker is designed with thermal storage arrangement. In this paper, a hybrid solar cooker with evacuated tube collector and latent thermal storage unit and alternate electric heatingsource is simulated. The...

  14. The utilization of dual source CT in imaging of polytrauma

    Energy Technology Data Exchange (ETDEWEB)

    Nicolaou, S. [University of British Columbia, Vancouver General Hospital, Department of Radiology, 899 West 12th Avenue, Vancouver, British Columbia, V5Z1M9 (Canada)], E-mail: savvas.nicolaou@vch.ca; Eftekhari, A.; Sedlic, T.; Hou, D.J.; Mudri, M.J.; Aldrich, John; Louis, L. [University of British Columbia, Vancouver General Hospital, Department of Radiology, 899 West 12th Avenue, Vancouver, British Columbia, V5Z1M9 (Canada)

    2008-12-15

    Despite the growing role of imaging, trauma remains the leading cause of death in people below the age of 45 years in the western industrialized countries. Trauma has been touted as the largest epidemic in the 20th century. The advent of MDCT has been the greatest advance in trauma care in the last 25 years. However, there are still challenges in CT imaging of the polytrauma individual including time restraints, diagnostic errors, radiation dose effects and bridging the gap between anatomy and physiology. This article will analyze these challenges and provide possible solutions offered by the unique design of the dual source CT scanner.

  15. The utilization of dual source CT in imaging of polytrauma

    International Nuclear Information System (INIS)

    Nicolaou, S.; Eftekhari, A.; Sedlic, T.; Hou, D.J.; Mudri, M.J.; Aldrich, John; Louis, L.

    2008-01-01

    Despite the growing role of imaging, trauma remains the leading cause of death in people below the age of 45 years in the western industrialized countries. Trauma has been touted as the largest epidemic in the 20th century. The advent of MDCT has been the greatest advance in trauma care in the last 25 years. However, there are still challenges in CT imaging of the polytrauma individual including time restraints, diagnostic errors, radiation dose effects and bridging the gap between anatomy and physiology. This article will analyze these challenges and provide possible solutions offered by the unique design of the dual source CT scanner

  16. Dual-source CT cardiac imaging: initial experience

    International Nuclear Information System (INIS)

    Johnson, Thorsten R.C.; Nikolaou, Konstantin; Wintersperger, Bernd J.; Rist, Carsten; Buhmann, Sonja; Reiser, Maximilian F.; Becker, Christoph R.; Leber, Alexander W.; Ziegler, Franz von; Knez, Andreas

    2006-01-01

    The relation of heart rate and image quality in the depiction of coronary arteries, heart valves and myocardium was assessed on a dual-source computed tomography system (DSCT). Coronary CT angiography was performed on a DSCT (Somatom Definition, Siemens) with high concentration contrast media (Iopromide, Ultravist 370, Schering) in 24 patients with heart rates between 44 and 92 beats per minute. Images were reconstructed over the whole cardiac cycle in 10% steps. Two readers independently assessed the image quality with regard to the diagnostic evaluation of right and left coronary artery, heart valves and left ventricular myocardium for the assessment of vessel wall changes, coronary stenoses, valve morphology and function and ventricular function on a three point grading scale. The image quality ratings at the optimal reconstruction interval were 1.24±0.42 for the right and 1.09±0.27 for the left coronary artery. A reconstruction of diagnostic systolic and diastolic images is possible for a wide range of heart rates, allowing also a functional evaluation of valves and myocardium. Dual-source CT offers very robust diagnostic image quality in a wide range of heart rates. The high temporal resolution now also makes a functional evaluation of the heart valves and myocardium possible. (orig.)

  17. Comprehensive thermodynamic analysis of a renewable energy sourced hybrid heating system combined with latent heat storage

    International Nuclear Information System (INIS)

    Utlu, Zafer; Aydın, Devrim; Kıncay, Olcay

    2014-01-01

    Highlights: • An experimental thermal investigation of hybrid renewable heating system is presented. • Analyses were done by using real data obtained from a prototype structure. • Exergy efficiency of system components investigated during discharging period are close to each other as 32%. • The average input energy and exergy rates to the LHS were 0.770 and 0.027 kW. • Overall total energy and exergy efficiencies of LHS calculated as 72% and 28.4%. - Abstract: In this study an experimental thermal investigation of hybrid renewable heating system is presented. Latent heat storage stores energy, gained by solar collectors and supplies medium temperature heat to heat pump both day time also night time while solar energy is unavailable. In addition to this an accumulation tank exists in the system as sensible heat storage. It provides supply–demand balance with storing excess high temperature heat. Analyses were done according to thermodynamic’s first and second laws by using real data obtained from a prototype structure, built as part of a project. Results show that high percent of heat loses took place in heat pump with 1.83 kW where accumulator-wall heating cycle followed it with 0.42 kW. Contrarily highest break-down of exergy loses occur accumulator-wall heating cycle with 0.28 kW. Averagely 2.42 kW exergy destruction took place in whole system during the experiment. Solar collectors and heat pump are the promising components in terms of exergy destruction with 1.15 kW and 1.09 kW respectively. Exergy efficiency of system components, investigated during discharging period are in a close approximately of 32%. However, efficiency of solar collectors and charging of latent heat storage are 2.3% and 7% which are relatively low. Average overall total energy and exergy efficiencies of latent heat storage calculated as 72% and 28.4% respectively. Discharging energy efficiency of latent heat storage is the highest through all system components. Also heat

  18. Simulation study of two-ion hybrid resonance heating

    International Nuclear Information System (INIS)

    Riyopoulos, S.; Tajima, T.

    1986-02-01

    A one-dimensional low-noise, low-frequency electromagnetic particle simulation code that is appropriate for investigation of ion cyclotron resonance heating (ICRH) is developed. Retaining the hyperbolicity of the electromagnetic waves and exploiting nearly one-dimensional characteristics (perpendicular to the external magnetic field) of the ICRH, we use the guiding center electron approximation for the transverse electronic current calculation. We observe mode conversion of the incoming magnetosonic wave into the electrostatic ion-ion hybrid mode accompanied by strong ion-heating. The dependence of this heating on the different plasma parameters is examined through a series of simulations, focusing mainly on wave incidence from the high field side. Because K/sub parallel/ = 0 in our runs, the conventional Landau damping cannot explain the ion heating. Non-linear mechanisms for energy transfer are discussed. Our numerical results demonstrate the importance of the non-linear wave particle interaction for energy transfer are discussed. Our numerical results demonstrate the importance of the non-linear wave particle interaction for energy absorption during radio frequency heating in the ion cyclotron regime. 32 refs., 17 figs

  19. Performance of a hybrid chemical/mechanical heat pump

    Science.gov (United States)

    Silvestri, John J.; Scaringe, Robert P.; Grzyll, Lawrence R.

    1990-01-01

    The authors present the design and preliminary results of the performance of a hybrid chemical/mechanical, low-lift (20 C) heat pump. Studies have indicated that this heat pump has several advantages over the traditional single fluid vapor compression (reverse Rankine) heat pump. Included in these benefits are: 1) increased COPc due to the approximation of the cycle to the Lorenz cycle and due to the availability of the heat of solution, along with the heat of vaporization, to provide cooling; and 2) ease of variation in system cooling capacity by changing the fluid composition. The system performance is predicted for a variety of refrigerant-absorbent pairs. Cooling capacity is determined for systems operating with ammonia as the refrigerant and lithium nitrate and sodium thiocyanate as the absorbents and also with water as the refrigerant and magnesium chloride, potassium hydroxide, lithium bromide, sodium hydroxide, and sulfuric acid as the absorbents. Early indications have shown that the systems operating with water as the refrigerant operate at 2-4 times the capacity of the ammonia-refrigerant-based systems. Using existing working fluids in the proposed innovative design, a coefficient-of-performance improvement of 21 percent is possible when compared to the best vapor compression systems analyzed.

  20. Experimental study on a hybrid photovoltaic/heat pump system

    International Nuclear Information System (INIS)

    Chen Hongbing; Riffat, Saffa B.; Fu Yu

    2011-01-01

    Several studies have found that the decrease of photovoltaic (PV) cell temperature would increase the solar-to-electricity conversion efficiency. Different working fluids such as air and water have been used for the cooling of PV modules, but the improvement in energy performance has been found to be small. In this paper, R134a refrigerant was employed to cool the PV modules. With its low evaporating temperature, it was expected to achieve better cooling effect and electrical performance of the PV modules than using air and water working fluids. An experimental rig of a hybrid micro PV panel-based heat pump system was constructed for the performance testing in a laboratory at University of Nottingham. A small PV panel was made of 6 glass vacuum tube - PV module - aluminium sheet - cooper tube (GPAC) sandwiches connected in series, acting as the evaporator. This was coupled with a small heat pump system. The glass vacuum tubes reduced the heat loss from the PV panel to the ambient, resulting in the improvement of thermal performance. Three testing modes were proposed to investigate the effect of solar radiation, condenser water flow rate and condenser water supply temperature on energy performance. The testing results showed that an averaged COP reached 3.8, 4.3 and 4.0 under the three testing modes with variable radiation, condenser water supply water temperature and water flow rate, respectively, but this could be much higher for a large capacity heat pump system using large PV panels on building roofs. The COP increased with the increasing solar radiation, but decreased with the increasing condenser water supply temperature and water flow rate. The electrical efficiency of PV panel was improved by up to 1.9% based on a reference PV efficiency of 3.9%, compared with that without cooling. The condenser water supply temperature and water flow rate had little effect on the electrical performance. - Highlights: → R134a refrigerant was used for cooling of PV modules

  1. Hybrid heat recovery - flat plate Stirling engine system

    International Nuclear Information System (INIS)

    Bogdanizh, A.M.; Budin, R.; Sutlovizh, I.

    2000-01-01

    In this paper, the possibility of process condensate heat recovery for boiler water preheating as well as for combined heat and power production for chosen process in textile industry has been investigated. The garment industry requires low pressure process steam or hot water for which production expensive fossil fuel should be used. Fuel usage can be reduced by various energy conservation methods. During the process a great quantity of hot condensate or waste hot water is rejected in the sewage system. To reduce heat wastes and improve technological process this condensate could be returned to the boiler for feed water preheating. When 60% condensate is returned to the steam generator about 8 % natural gas is saved. The rest of the condensate should be used for driving low temperature flat plate Stirling motor the advantage of the flat plate Stirling engine is ability to work at low temperatures. This engine produces electrical energy which can put in motion an electrogenerator in the same plant. While Stirling engine can be used electrical power and economical effect could be much greater using such a hybrid system the process waste heat is not only converted into useful work but at the same time thermal pollution is greatly diminished. (Author)

  2. Rectification of electronic heat current by a hybrid thermal diode.

    Science.gov (United States)

    Martínez-Pérez, Maria José; Fornieri, Antonio; Giazotto, Francesco

    2015-04-01

    Thermal diodes--devices that allow heat to flow preferentially in one direction--are one of the key tools for the implementation of solid-state thermal circuits. These would find application in many fields of nanoscience, including cooling, energy harvesting, thermal isolation, radiation detection and quantum information, or in emerging fields such as phononics and coherent caloritronics. However, both in terms of phononic and electronic heat conduction (the latter being the focus of this work), their experimental realization remains very challenging. A highly efficient thermal diode should provide a difference of at least one order of magnitude between the heat current transmitted in the forward temperature (T) bias configuration (Jfw) and that generated with T-bias reversal (Jrev), leading to ℛ = Jfw/Jrev ≫ 1 or ≪ 1. So far, ℛ ≈ 1.07-1.4 has been reported in phononic devices, and ℛ ≈ 1.1 has been obtained with a quantum-dot electronic thermal rectifier at cryogenic temperatures. Here, we show that unprecedentedly high ratios of ℛ ≈ 140 can be achieved in a hybrid device combining normal metals tunnel-coupled to superconductors. Our approach provides a high-performance realization of a thermal diode for electronic heat current that could be successfully implemented in true low-temperature solid-state thermal circuits.

  3. Study on hybrid ground-coupled heat pump systems

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Man; Hongxing, Yang [Renewable Energy Research Group, The Hong Kong Polytechnic University, Hong Kong (China); Zhaohong, Fang [School of Thermal Energy Engineering, Shandong Architecture University, Jinan (China)

    2008-07-01

    Although ground-coupled heat pump (GCHP) systems are becoming attractive air-conditioning systems in some regions, the significant drawback for their wider application is the high initial cost. Besides, more energy is rejected into ground by the GCHP system installed in cooling-dominated buildings than the energy extracted from ground on an annual basis and this imbalance can result in the degradation of system performance. One of the available options that can resolve these problems is to apply the hybrid ground-coupled heat pump (HGCHP) systems, with supplemental heat rejecters for rejecting extra thermal energy when they are installed in cooling-dominated buildings. This paper presents a practical hourly simulation model of the HGCHP system by modeling the heat transfer of its main components. The computer program developed on this hourly simulation model can be used to calculate the operating data of the HGCHP system according to the building load. The design methods and running control strategies of the HGCHP system for a sample building are investigated. The simulation results show that proper HGCHP system can effectively reduce both the initial cost and the operating cost of an air-conditioning system compared with the traditional GCHP system used in cooling-dominated buildings. (author)

  4. Hybrid heat pipe based passive cooling device for spent nuclear fuel dry storage cask

    International Nuclear Information System (INIS)

    Jeong, Yeong Shin; Bang, In Cheol

    2016-01-01

    Highlights: • Hybrid heat pipe was presented as a passive cooling device for dry storage cask of SNF. • A method to utilize waste heat from spent fuel was suggested using hybrid heat pipe. • CFD analysis was performed to evaluate the thermal performance of hybrid heat pipe. • Hybrid heat pipe can increase safety margin and storage capacity of the dry storage cask. - Abstract: Conventional dry storage facilities for spent nuclear fuel (SNF) were designed to remove decay heat through the natural convection of air, but this method has limited cooling capacity and a possible re-criticality accident in case of flooding. To enhance the safety and capacity of dry storage cask of SNF, hybrid heat pipe-based passive cooling device was suggested. Heat pipe is an excellent passive heat transfer device using the principles of both conduction and phase change of the working fluid. The heat pipe containing neutron absorber material, the so-called hybrid heat pipe, is expected to prevent the re-criticality accidents of SNF and to increase the safety margin during interim and long term storage period. Moreover, a hybrid heat pipe with thermoelectric module, a Stirling engine and a phase change material tank can be used for utilization of the waste heat as heat-transfer medium. Located at the guide tube or instrumentation tube, hybrid heat pipe can remove decay heat from inside the sealed metal cask to outside, decreasing fuel rod temperature. In this paper, a 2-step analysis was performed using computational fluid dynamics code to evaluate the heat and fluid flow inside a cask, which consisted of a single spent fuel assembly simulation and a full-scope dry cask simulation. For a normal dry storage cask, the maximum fuel temperature is 290.0 °C. With hybrid heat pipe cooling, the temperature decreased to 261.6 °C with application of one hybrid heat pipe per assembly, and to 195.1 °C with the application of five hybrid heat pipes per assembly. Therefore, a dry

  5. Influence of electrical and hybrid heating on bread quality during baking

    OpenAIRE

    Chhanwal, N.; Ezhilarasi, P. N.; Indrani, D.; Anandharamakrishnan, C.

    2014-01-01

    Energy efficiency and product quality are the key factors for any food processing industry. The aim of the study was to develop energy and time efficient baking process. The hybrid heating (Infrared + Electrical) oven was designed and fabricated using two infrared lamps and electric heating coils. The developed oven can be operated in serial or combined heating modes. The standardized baking conditions were 18 min at 220°C to produce the bread from hybrid heating oven. Effect of baking with h...

  6. Simulation of hybrid ground-coupled heat pump with domestic hot water heating systems using HVACSIM+

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Ping; Yang, Hongxing [Department of Building Services Engineering, The Hong Kong Polytechnic University, Hong Kong (China); Spitler, Jeffrey D. [School of Mechanical Engineering, Oklahoma State University (United States); Fang, Zhaohong [Ground Source Heat Pump Research Center, Shandong University of Architecture and Engineering, Jinan (China)

    2008-07-01

    A hybrid ground-coupled heat pump (HGCHP) with domestic hot water (DHW) supply system has been proposed in this paper for space cooling/heating and DHW supply for residential buildings in hot-climate areas. A simulation model for this hybrid system is established within the HVACSIM+ environment. A sample system, applied for a small residential apartment located in Hong Kong, is hourly simulated in a typical meteorological year. The conventional GCHP system and an electric heater for DHW supply are also modeled and simulated on an hourly basis within the HVACSIM+ for comparison purpose. The results obtained from this case study show that the HGCHP system can effectively alleviate the imbalanced loads of the ground heat exchanger (GHE) and can offer almost 95% DHW demand. The energy saving for DHW heating is about 70% compared with an electric heater. This proposed scheme, i.e. the HGCHP with DHW supply, is suitable to residential buildings in hot-climate areas, such as in Hong Kong. (author)

  7. Household preferences of hybrid home heating systems – A choice experiment application

    International Nuclear Information System (INIS)

    Ruokamo, Enni

    2016-01-01

    The residential heating sector presents considerable energy savings potential, as numerous heating solutions for reducing electricity consumption and utilizing renewable energy sources are available in the market. The aim of this paper is to examine determinants of household heating system choices and to use this information for policy planning purposes. This paper investigates residential homeowner attitudes regarding innovative hybrid home heating systems (HHHS) with choice experiment. Heating system scenarios are designed to represent the most relevant primary and supplementary heating alternatives currently available in Finland. The choice sets include six main heating alternatives (district heat, solid wood, wood pellet, electric storage heating, ground heat pump and exhaust air heat pump) that are described by five attributes (supplementary heating systems, investment costs, operating costs, comfort of use and environmental friendliness). The results imply that HHHSs generally appear to be accepted among households; however, several factors affect perceptions of these technologies. The results reveal differing household attitudes toward the main heating alternatives and show that such views are affected by socio-demographic characteristics (age, living environment, education, etc.). The results suggest that households view supplementary heating systems (especially solar-based) favorably. The other attributes studied also play a significant role in decision making. - Highlights: •Study of hybrid heating where supplementary and main heating systems are combined. •Choice experiment is applied to study the determinants of hybrid heating adoption. •Hybrid heating appears to be generally accepted among households. •Households exhibit differing attitudes toward hybrid heating. •Policy makers should not underestimate the potential of hybrid heating.

  8. Numerical modeling of lower hybrid heating and current drive

    International Nuclear Information System (INIS)

    Valeo, E.J.; Eder, D.C.

    1986-03-01

    The generation of currents in toroidal plasma by application of waves in the lower hybrid frequency range involves the interplay of several physical phenomena which include: wave propagation in toroidal geometry, absorption via wave-particle resonances, the quasilinear generation of strongly nonequilibrium electron and ion distribution functions, and the self-consistent evolution of the current density in such a nonequilibrium plasma. We describe a code, LHMOD, which we have developed to treat these aspects of current drive and heating in tokamaks. We present results obtained by applying the code to a computation of current ramp-up and to an investigation of the possible importance of minority hydrogen absorption in a deuterium plasma as the ''density limit'' to current drive is approached

  9. Design of serially connected ammonia-water hybrid absorption-compression heat pumps for district heating with the utilisation of a geothermal heat source

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Ommen, Torben Schmidt; Markussen, Wiebke Brix

    2016-01-01

    District heating (DH) can reduce the primary energy consumption in urban areas with significant heat demands. The design of a serially connected ammonia-water hybrid absorption-compression heat pump system was investigated for operation in the Greater Copenhagen DH network in Denmark, in order...... to supply 7.2 MW heat at 85 °C utilizing a geothermal heat source at 73 °C. Both the heat source and heat sink experience a large temperature change over the heat transfer process, of which a significant part may be achieved by direct heat exchange. First a generic study with a simple representation...

  10. Technical and economical feasibility of the hybrid adsorption compression heat pump concept for industrial applications

    International Nuclear Information System (INIS)

    Pal, Michel van der; Wemmers, Anton; Smeding, Simon; Boer, Robert de

    2013-01-01

    Heat pump technologies offer a significant potential for primary energy savings in industrial processes. Thermally driven heat pumps can use waste heat as driving energy source to provide either heating or cooling. A chemi-sorption heat transformer can upgrade a waste heat source to temperatures of 150–200 °C. The specific heat transformer process however requires waste heat temperatures in the range of 120 °C, whereas waste heat sources of lower temperatures are more abundant. Using this lower temperature waste heat, and still reach the desired higher output temperatures can be achieved by the integration of a chemisorption and mechanical compression step in a single hybrid heat pump concept. This concept can offer an increased flexibility in temperatures, both for the waste heat source as for the heat delivery. The technical and economical feasibility of the proposed hybrid heat pump concept is evaluated. The range of operating temperatures of different chemi-sorption working pairs for as heat driven and as hybrid systems are defined, as well as their energy efficiencies. Investment costs for the hybrid systems are derived and payback times are calculated. The range of payback times is from 2 to 9 years and are strongly influenced by the number of operating hours, the electrical COP of the compression stage, and the energy prices

  11. Dual-source CT in chest pain diagnosis

    International Nuclear Information System (INIS)

    Johnson, Thorsten R.C.; Nikolaou, K.; Fink, C.; Rist, C.; Reiser, M.F.; Becker, C.R.; Becker, A.; Knez, A.

    2007-01-01

    With the depiction of pulmonary arteries, coronary arteries, and the aorta, CT angiography of the chest offers a comprehensive diagnostic work-up of unclear chest pain. The aim of this study was to assess the diagnostic accuracy of dual-source CT in this patient group. A total of 47 patients suffering from unclear chest pain were examined with a Siemens Somatom Definition. Volume and flow of contrast media (Ultravist, Schering) were adapted to the body weight. The examinations were evaluated with regard to image quality and contrast opacification and to the diagnostic accuracy with reference to the final clinical diagnosis. Adequate contrast opacification was achieved in all examinations. The depiction of the coronary arteries was diagnostic in all cases. The cause of chest pain could be identified in 41 cases. Among the diagnoses were coronary and myocardial pathologies, valvular disease, aortic aneurysms and dissections, pulmonary embolism, and pneumonic consolidation. DSCT angiography of the chest offers a very good image quality even at high heart rates so that a high diagnostic accuracy is achieved in patients with acute chest pain. (orig.) [de

  12. Lower-hybrid heating and current drive on PLT

    International Nuclear Information System (INIS)

    Hooke, W.; Bernabei, S.; Boyd, D.

    1983-02-01

    Steady currents up to 165 kA for 3.5 seconds and 420 kA for 0.3 seconds have been maintained by 800 MHz lower hybrid waves. For line-averaged densities up to 7 x 10 12 cm - 3 the current is maintained with no input power from the ohmic heating transformer. The waves are launched with an array of six waveguides. Measurements of X rays and electron cyclotron radiation show that the rf power produces and maintains a suprathermal tail of electrons apparently independent of the number of fast electrons in the plasma prior to turning on the rf power. Measurements of current-drive efficiency and the electron tail provide direct evidence for a resonant wave-particle interaction. The radial profile of the rf-sustained current inferred from x-ray measurements is peaked in the center of the plasma and appears to obey the same q-value restraints as the inductively driven ohmic heating current. Current drive is observed to be accompanied always by radiation at frequencies greater than or equal to #betta#/sub ce/ and less than or equal to #betta#/sub pe/. The connection between this radiation and the current-drive mechanism is under study

  13. Lower hybrid waves for current drive and heating in reactors

    International Nuclear Information System (INIS)

    Yugo, J.; Bernabei, S.; Bonoli, P.; Devoto, R.S.; Fenstermacher, M.; Porkolab, M.; Stevens, J.

    1988-01-01

    Lower hybrid (LH) waves are projected to be an important ingredient for current drive and heating in steady-state operation of reactors, such as the International Thermonuclear Experimental Reactor (ITER) or later power producing tokamaks. We have examined the required frequency and spectrum for such applications and designed a system to meet the specifications. We found that, to avoid damping of LH waves on alpha particles the frequency should be at least 6--8 GHz. At a typical volume average temperature of 14 keV, the LH rays penetrate about 30% of the minor radius, or to about 15 KeV, when N/sub parallel/ is chosen to maximize penetration and the spectral width, ΔN/sub parallel/ is about 0.05 (full width at 0.5 of spectral peak). For use in low density current ramp-up and transformer recharging, N/sub parallel/ is dynamically controlled. We have designed an LH system that satisfies requirements similar to those expected for ITER. It provides a Brambilla array which can be tuned from N/sub parallel/ of 1.0--2.8. An analysis has been performed to evaluate nuclear (1--2 MW/m 2 ), plasma radiation, and rf heating of the LH launcher. 4 refs., 3 figs., 4 tabs

  14. Experimental and simulation study on the plate absorber for hybrid heat pump system

    Energy Technology Data Exchange (ETDEWEB)

    An, Seung Sun; Jung, Chung Woo; Kang, Yong Tae [Kyung Hee University, Yongin (Korea, Republic of); Kim, Min Sung; Park, Seong Ryong [KIER, Daejeon (Korea, Republic of); Kang, Chae Dong [Chonbuk National University, Jeonju (Korea, Republic of)

    2013-12-15

    This research conducts an experiment for a hybrid heat pump system, using ammonia-water as a working fluid, to obtain a hot water of about 80 .deg. C. The hybrid heat pump system is the combination of vapor compression cycle and absorption cycle to improve the performance of the heat pump system. The hybrid heat pump system uses a low temperature heat source of about 50 .deg. C from the industrial waste heat. The system consists of absorber, desorber, solution heat exchanger, oil heat exchanger, rectifier, compressor and a solution pump. Parametric analysis is carried out experimentally and numerically for the key parameters such as the capacity of the absorber, the internal pressure change. From the present experimental study, it is found that the maximum hot water temperature is obtained to be 79.33 .deg. C.

  15. Influence of electrical and hybrid heating on bread quality during baking.

    Science.gov (United States)

    Chhanwal, N; Ezhilarasi, P N; Indrani, D; Anandharamakrishnan, C

    2015-07-01

    Energy efficiency and product quality are the key factors for any food processing industry. The aim of the study was to develop energy and time efficient baking process. The hybrid heating (Infrared + Electrical) oven was designed and fabricated using two infrared lamps and electric heating coils. The developed oven can be operated in serial or combined heating modes. The standardized baking conditions were 18 min at 220°C to produce the bread from hybrid heating oven. Effect of baking with hybrid heating mode (H-1 and H-2, hybrid oven) on the quality characteristics of bread as against conventional heating mode (C-1, pilot scale oven; C-2, hybrid oven) was studied. The results showed that breads baked in hybrid heating mode (H-2) had higher moisture content (28.87%), higher volume (670 cm(3)), lower crumb firmness value (374.6 g), and overall quality score (67.0) comparable to conventional baking process (68.5). Moreover, bread baked in hybrid heating mode showed 28% reduction in baking time.

  16. Flexible and stable heat energy recovery from municipal wastewater treatment plants using a fixed-inverter hybrid heat pump system

    International Nuclear Information System (INIS)

    Chae, Kyu-Jung; Ren, Xianghao

    2016-01-01

    Highlights: • Specially designed fixed-inverter hybrid heat pump system was developed. • Hybrid operation performed better at part loads than single inverter operation. • The applied heat pump can work stably over a wide range of heat load variations. • Heat energy potential of treated effluent was better than influent. • The heat pump’s COP from the field test was 4.06 for heating and 3.64 for cooling. - Abstract: Among many options to improve energy self-sufficiency in sewage treatment plants, heat extraction using a heat pump holds great promise, since wastewater contains considerable amounts of thermal energy. The actual heat energy demand at municipal wastewater treatment plants (WWTPs) varies widely with time; however, the heat pumps typically installed in WWTPs are of the on/off controlled fixed-speed type, thus mostly run intermittently at severe part-load conditions with poor efficiency. To solve this mismatch, a specially designed, fixed-inverter hybrid heat pump system incorporating a fixed-speed compressor and an inverter-driven, variable-speed compressor was developed and tested in a real WWTP. In this hybrid configuration, to improve load response and energy efficiency, the base-heat load was covered by the fixed-speed compressor consuming relatively less energy than the variable-speed type at nominal power, and the remaining varying load was handled by the inverter compressor which exhibits a high load-match function while consuming relatively greater energy. The heat pump system developed reliably extracted heat from the treated effluent as a heat source for heating and cooling purposes throughout the year, and actively responded to the load changes with a high measured coefficient of performance (COP) of 4.06 for heating and 3.64 for cooling. Moreover, this hybrid operation yielded a performance up to 15.04% better on part loads than the single inverter operation, suggesting its effectiveness for improving annual energy saving when

  17. Study on hybrid heat source overlap welding of magnesium alloy AZ31B

    International Nuclear Information System (INIS)

    Liang, G.L.; Zhou, G.; Yuan, S.Q.

    2009-01-01

    The magnesium alloy AZ31B was overlap welded by hybrid welding (laser-tungsten inert gas arc). According to the hybrid welding interaction principle, a new heat source model, hybrid welding heat source model, was developed with finite element analysis. At the same time, using a high-temperature metallographical microscope, the macro-appearance and microstructure characteristics of the joint after hybrid overlap welding were studied. The results indicate that the hybrid welding was superior to the single tungsten inert gas welding or laser welding on the aspects of improving the utilized efficiency of the arc and enhancing the absorptivity of materials to laser energy. Due to the energy characteristics of hybrid overlap welding the macro-appearance of the joint was cup-shaped, the top weld showed the hybrid welding microstructure, while, the lower weld showed the typical laser welding microstructure

  18. Study on hybrid heat source overlap welding of magnesium alloy AZ31B

    Energy Technology Data Exchange (ETDEWEB)

    Liang, G.L. [Department of Electromechanical Engineering, Tangshan College, Tangshan 063000 (China)], E-mail: guoliliang@sohu.com; Zhou, G. [School of Material Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Yuan, S.Q. [Department of Electromechanical Engineering, Tangshan College, Tangshan 063000 (China)

    2009-01-15

    The magnesium alloy AZ31B was overlap welded by hybrid welding (laser-tungsten inert gas arc). According to the hybrid welding interaction principle, a new heat source model, hybrid welding heat source model, was developed with finite element analysis. At the same time, using a high-temperature metallographical microscope, the macro-appearance and microstructure characteristics of the joint after hybrid overlap welding were studied. The results indicate that the hybrid welding was superior to the single tungsten inert gas welding or laser welding on the aspects of improving the utilized efficiency of the arc and enhancing the absorptivity of materials to laser energy. Due to the energy characteristics of hybrid overlap welding the macro-appearance of the joint was cup-shaped, the top weld showed the hybrid welding microstructure, while, the lower weld showed the typical laser welding microstructure.

  19. Heating tokamaks via the ion-cyclotron and ion-ion hybrid resonances

    International Nuclear Information System (INIS)

    Perkins, F.W.

    1977-04-01

    For the ion-ion hybrid resonance it is shown that: (1) the energy absorption occurs via a sequence of mode conversions; (2) a poloidal field component normal to the ion-ion hybrid mode conversion surface strongly influences the mode conversion process so that roughly equal electron and ion heating occurs in the present proton-deuterium experiments, while solely electron heating is predicted to prevail in deuterium-tritium reactors; (3) the ion-ion hybrid resonance suppresses toroidal eigenmodes; and (4) wave absorption in minority fundamental ion-cyclotron heating experiments will be dominated by ion-ion hybrid mode conversion absorption for minority concentrations exceeding roughly 1 percent. For the ion-cyclotron resonance, it is shown that: (1) ion-cyclotron mode conversion leads to surface electron heating; and (2) ion-cyclotron mode conversion absorption dominates fundamental ion-cyclotron absorption thereby preventing efficient ion heating

  20. Kalman Filtered Bio Heat Transfer Model Based Self-adaptive Hybrid Magnetic Resonance Thermometry.

    Science.gov (United States)

    Zhang, Yuxin; Chen, Shuo; Deng, Kexin; Chen, Bingyao; Wei, Xing; Yang, Jiafei; Wang, Shi; Ying, Kui

    2017-01-01

    To develop a self-adaptive and fast thermometry method by combining the original hybrid magnetic resonance thermometry method and the bio heat transfer equation (BHTE) model. The proposed Kalman filtered Bio Heat Transfer Model Based Self-adaptive Hybrid Magnetic Resonance Thermometry, abbreviated as KalBHT hybrid method, introduced the BHTE model to synthesize a window on the regularization term of the hybrid algorithm, which leads to a self-adaptive regularization both spatially and temporally with change of temperature. Further, to decrease the sensitivity to accuracy of the BHTE model, Kalman filter is utilized to update the window at each iteration time. To investigate the effect of the proposed model, computer heating simulation, phantom microwave heating experiment and dynamic in-vivo model validation of liver and thoracic tumor were conducted in this study. The heating simulation indicates that the KalBHT hybrid algorithm achieves more accurate results without adjusting λ to a proper value in comparison to the hybrid algorithm. The results of the phantom heating experiment illustrate that the proposed model is able to follow temperature changes in the presence of motion and the temperature estimated also shows less noise in the background and surrounding the hot spot. The dynamic in-vivo model validation with heating simulation demonstrates that the proposed model has a higher convergence rate, more robustness to susceptibility problem surrounding the hot spot and more accuracy of temperature estimation. In the healthy liver experiment with heating simulation, the RMSE of the hot spot of the proposed model is reduced to about 50% compared to the RMSE of the original hybrid model and the convergence time becomes only about one fifth of the hybrid model. The proposed model is able to improve the accuracy of the original hybrid algorithm and accelerate the convergence rate of MR temperature estimation.

  1. Exergoeconomic optimization of an ammonia–water hybrid absorption–compression heat pump for heat supply in a spraydrying facility

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Markussen, Wiebke Brix; Reinholdt, Lars

    2015-01-01

    Spray-drying facilities are among the most energy intensive industrial processes. Using a heat pump to recover waste heat and replace gas combustion has the potential to attain both economic and emissions savings. In the case examined a drying gas of ambient air is heated to 200 C yielding a heat...... load of 6.1 MW. The exhaust air from the drying process is 80 C. The implementation of anammonia–water hybrid absorption–compression heat pump to partly cover the heat load is investigated. A thermodynamic analysis is applied to determine optimal circulation ratios for a number of ammonia mass...... fractions and heat pump loads. An exergo economic optimization is applied to minimize the lifetime cost of the system. Technological limitations are imposed to constrain the solution to commercial components. The best possible implementation is identified in terms of heat load, ammonia mass fraction...

  2. Performance optimum analysis of an irreversible molten carbonate fuel cell–Stirling heat engine hybrid system

    International Nuclear Information System (INIS)

    Chen, Liwei; Zhang, Houcheng; Gao, Songhua; Yan, Huixian

    2014-01-01

    A new hybrid system mainly consists of a molten carbonate fuel cell (MCFC) and a Stirling heat engine is established, where the Stirling heat engine is driven by the high-quality waste heat generated in the MCFC. Based on the electrochemistry and non-equilibrium thermodynamics, analytical expressions for the efficiency and power output of the hybrid system are derived by taking various irreversible losses into account. It shows that the performance of the MCFC can be greatly enhanced by coupling a Stirling heat engine to further convert the waste heat for power generation. By employing numerical calculations, not only the influences of multiple irreversible losses on the performance of the hybrid system are analyzed, but also the impacts of some operating conditions such as the operating temperature, input gas compositions and operating pressure on the performance of the hybrid system are also discussed. The investigation method in the present paper is feasible for some other similar energy conversion systems as well. - Highlights: • A model of MCFC–Stirling heat engine hybrid system is established. • Analytical expressions for the efficiency and power output are derived. • MCFC performance can be greatly enhanced by coupling a Stirling heat engine. • Effects of some operating conditions on the performance are discussed. • Optimum operation regions are subdivided by multi-objective optimization method

  3. Technical and economic working domains of industrial heat pumps: Part 2 - ammonia-water hybrid absorption-compression heat pumps

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Ommen, Torben Schmidt; Markussen, Wiebke Brix

    2015-01-01

    The ammonia-water hybrid absorption-compression heat pump (HACHP) has been proposed as a relevant technology for industrial heat supply, especially for high sink temperatures and high temperature glides in the sink and source. This is due to the reduced vapour pressure and the non-isothermal phase...... change of the zeotropic mixture, ammonia-water. To evaluate to which extent these advantages can be translated into feasible heat pump solutions, the working domain of the HACHP is investigated based on technical and economic constraints. The HACHP working domain is compared to that of the best available...... vapour compression heat pump with natural working fluids. This shows that the HACHP increases the temperature lifts and heat supply temperatures that are feasible to produce with a heat pump. The HACHP is shown to be capable of delivering heat supply temperatures as high as 150 °C and temperature lifts...

  4. Technical and Economic Working Domains of Industrial Heat Pumps: Part 2 - Ammonia-Water Hybrid Absorption-Compression Heat Pumps

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Ommen, Torben Schmidt; Markussen, Wiebke Brix

    2014-01-01

    The ammonia-water hybrid absorption-compression heat pump (HACHP) is a relevant technology for industrial heat supply, especially for high sink temperatures and high temperature glides in the sink and source. This is due to the reduced vapour pressure and the non-isothermal phase change...... of the zeotropic mixture, ammonia-water. To evaluate to which extent these advantages can be translated into feasible heat pump solutions, the working domain of the HACHP is investigated based on technical and economic constraints. The HACHP working domain is compared to that of the best possible vapour...... compression heat pump with natural working fluids. This shows that the HACHP increases the temperature lifts and heat supply temperatures that are feasible to produce with a heat pump. The HACHP is shown to be capable of delivering heat supply temperatures as high as 140 XC and temperature lifts up to 60 K...

  5. Exergoeconomic optimization of an ammonia-water hybrid heat pump for heat supply in a spray drying facility

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Markussen, Wiebke Brix; Reinholdt, Lars

    2014-01-01

    Spray drying facilities are among the most energy intensive industrial processes. Using a heat pump to recover waste heat and replace gas combustion has the potential to attain both economic and emissions savings. In the case examined a drying gas of ambient air is heated to 200 XC. The inlet flow...... rate is 100,000 m3/h which yields a heat load of 6.1 MW. The exhaust air from the drying process is 80 XC. The implementation of an ammonia-water hybrid absorption-compression heat pump to partly cover the heat load is investigated. A thermodynamic analysis is applied to determine optimal circulation...... ratios for a number of ammonia mass fractions and heat pump loads. An exergoeconomic optimization is applied to minimize the lifetime cost of the system. Technological limitations are applied to constrain the solution to commercial components. The best possible implementation is identified in terms...

  6. Hybrid coils having an improved heat transfer capability

    NARCIS (Netherlands)

    2008-01-01

    A hybrid coil ( 11 ) employs a wire layer ( 22 ), a wire layer ( 23 ) adjacent the wire layer ( 22 ), and a wire layer ( 24 ) adjacent the wire layer ( 23 ). The hybrid coil ( 11 ) further employs a thermal conductive insulator ( 42 ) physically disposed within a space between the wire layer ( 22 )

  7. Experimental research on thermal characteristics of a hybrid thermocline heat storage system

    International Nuclear Information System (INIS)

    Yin, Huibin; Ding, Jing; Yang, Xiaoxi

    2014-01-01

    Considering the high-temperature thermal utilization of solar energy as the research background in this paper and focussing on the heat storage process, a kind of hybrid thermocline heat storage method in multi-scale structure and relevant experimental systems are designed by using the mixed molten nitrate salt as the heat storage medium and two representative porous materials, i.e. zirconium ball and silicon carbide (SiC) foam, as the heat storage fillers. The fluid flow and heat storage performance of molten salt in multi-scale structure are experimentally investigated. The results show that the theoretical heat storage efficiencies amongst the three experimental heat storage manners are less than 80% because of the existence of thermocline layers. Comparing to the single-phase molten salt heat storage, the two hybrid thermocline heat storage manners with porous fillers lead to a certain decrease in the effective heat storage capacity. The presence of porous fillers can also help to maintain the molten salt fluid as ideal gravity flow or piston flow and partially replace expensive molten salt. Therefore, it requires a combination of heat storage capacity and economical consideration for optimization design when similar spherical particles or foam ceramics are employed as the porous fillers. -- Highlights: • A hybrid thermocline heat storage method in multi-scale structure is developed. • The fluid flow and heat storage performance are experimentally investigated. • Stable thermocline can form in single tank for the experimental cases. • The hybrid thermocline heat storage with porous filler is promising

  8. Performance analysis of hybrid ground-coupled heat pump system with multi-functions

    International Nuclear Information System (INIS)

    You, Tian; Wang, Baolong; Wu, Wei; Shi, Wenxing; Li, Xianting

    2015-01-01

    Highlights: • The hybrid GCHP system with multi-functions is proposed. • The system maintains the soil temperature and heating reliability steady. • The multi-functional operation of HCUT can save more energy of the system. - Abstract: Underground thermal imbalance is a significant problem for ground-coupled heat pump (GCHP) systems that serve predominately heated buildings in cold regions, which extract more heat from the ground and inject less heat, especially in buildings requiring domestic hot water (DHW). To solve this problem, a previously developed heat compensation unit with thermosyphon (HCUT) is integrated with a GCHP unit to build a hybrid GCHP system. To improve the energy savings of this hybrid GCHP system, the HCUT unit is set to have multiple functions (heat compensation, direct DHW and direct space heating) in this paper. To analyze the improved system performance, a hotel requiring air-conditioning and DHW is selected and simulated in three typical cold cities using the dynamic software DeST and TRNSYS. The results indicate that the hybrid GCHP system can maintain the underground thermal balance while keeping the indoor air temperature within the design range. Furthermore, the HCUT unit efficiently reduces the energy consumption via its multi-functional operations. Compared to the previous system that only used HCUT for heat compensation, adding the direct DHW function further saves 7.5–11.0% energy in heat compensation (HC) and DHW (i.e., 3.6–4.8% of the whole system). Simultaneously adding the direct DHW and space heating functions to the HCUT can save 9.8–12.9% energy in HC and DHW (i.e., 5.1–6.0% of the whole system). The hybrid GCHP system with a multi-functional HCUT provides more energy savings while maintaining the underground thermal balance in cold regions that demand both air-conditioning and DHW

  9. Heat Removal Performance of Hybrid Control Rod for Passive In-Core Cooling System

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyung Mo; Jeong, Yeong Shin; Kim, In Guk; Bang, In Cheol [UNIST, Ulsan (Korea, Republic of)

    2015-10-15

    The two-phase closed heat transfer device can be divided by thermosyphon heat pipe and capillary wicked heat pipe which uses gravitational force or capillary pumping pressure as a driving force of the convection of working fluid. If there is a temperature difference between reactor core and ultimate heat sink, the decay heat removal and reactor shutdown is possible at any accident conditions without external power sources. To apply the hybrid control rod to the commercial nuclear power plants, its modelling about various parameters is the most important work. Also, its unique geometry is coexistence of neutron absorber material and working fluid in a cladding material having annular vapor path. Although thermosyphon heat pipe (THP) or wicked heat pipe (WHP) shows high heat transfer coefficients for limited space, the maximum heat removal capacity is restricted by several phenomena due to their unique heat transfer mechanism. Validation of the existing correlations on the annular vapor path thermosyphon (ATHP) which has different wetted perimeter and heated diameter must be conducted. The effect of inner structure, and fill ratio of the working fluid on the thermal performance of heat pipe has not been investigated. As a first step of the development of hybrid heat pipe, the ATHP which contains neutron absorber in the concentric thermosyphon (CTHP) was prepared and the thermal performance of the annular thermosyphon was experimentally studied. The heat transfer characteristics and flooding limit of the annular vapor path thermosyphon was studied experimentally to model the performance of hybrid control rod. The following results were obtained: (1) The annular vapor path thermosyphon showed better evaporation heat transfer due to the enhanced convection between adiabatic and condenser section. (2) Effect of fill ratio on the heat transfer characteristics was negligible. (3) Existing correlations about flooding limit of thermosyphon could not reflect the annular vapor

  10. The role of hybrid nanofluids in improving the thermal characteristics of screen mesh cylindrical heat pipes

    Directory of Open Access Journals (Sweden)

    Ramachandran Raghavan Nair

    2016-01-01

    Full Text Available Experiments were conducted to study the thermal performance of meshed wick heat pipe by varying the working fluid and heat input. In this work four screen mesh wicked heat pipes were fabricated and tested. All the heat pipes were tested for heat input from 50W to 250W each with an increment of 50W in each step. The heat input range selected in this study is commonly encountered in most of the electronic application devices. The thermal resistance of all the heat pipes charged with different working fluids such as DI water, Al2O3/DI water nanofluid of volume concentration 0.1 % and hybrid nanofluid volume concentration 0.1%( with two different combinations of (Al2O3 50%- CuO 50%/DI water and (Al2O3 25%- CuO 75%/DI waterwas determined. The maximum percentage reduction was found to be 58.87% for the hybrid nanofluid of (Al2O3 25%- CuO 75%/DI water compared to base fluid. An important observation from the study is that, use of hybrid nanofluid can raise the operating range of the heat pipe beyond 250W which makes hybrid nanofluid as a potential substitute for the conventional working fluid.

  11. Innovative Hybrid CHP systems for high temperature heating plant in existing buildings

    NARCIS (Netherlands)

    de Santoli, Livio; Lo Basso, Gianluigi; Nastasi, B.; d’Ambrosio Alfano, Francesca R.; Mazzarella and Piercarlo, Livio

    2017-01-01

    This paper deals with the potential role of new hybrid CHP systems application providing both electricity and heat which are compatible with the building architectural and landscape limitations. In detail, three different plant layout options for high temperature heat production along with the

  12. Hybrid code simulation on mode conversion in the second harmonic ICRF heating

    International Nuclear Information System (INIS)

    Sakai, K.; Takeuchi, S.; Matsumoto, M.; Sugihara, R.

    1985-01-01

    ICRF second harmonic heating of a single-species plasma is studied by using a 1-1/2 dimensional quasi-neutral hybrid code. Mode conversion, transmission and reflection of the magnetosonic waves are confirmed, both for the high- and low-field-side excitations. The ion heating by waves propagating perpendicularly to the static magnetic field is also observed

  13. Analysis of the efficiency of a hybrid foil tunnel heating system

    Science.gov (United States)

    Kurpaska, Sławomir; Pedryc, Norbert

    2017-10-01

    The paper analyzes the efficiency of the hybrid system used to heat the foil tunnel. The tested system was built on the basis of heat gain in a cascade manner. The first step is to heat the water in the storage tank using the solar collectors. The second stage is the use of a heat pump (HP) in order to heat the diaphragm exchangers. The lower HP heat source is a cascade first stage buffer. In the storage tank, diaphragm exchangers used for solar collectors and heat pumps are installed. The research was carried out at a research station located in the University of Agriculture in Cracow. The aim was to perform an analysis of the efficiency of a hybrid system for the heating of a foil tunnel in the months from May to September. The efficiency of the entire hybrid system was calculated as the relation of the effect obtained in reference to the electrical power used to drive the heat pump components (compressor drive, circulation pump), circulation pumps and fans installed in the diaphragm heaters. The resulting effect was the amount of heat supplied to the interior of the object as a result of the internal air being forced through the diaphragm exchangers.

  14. Enhanced Thermal Management System for Spent Nuclear Fuel Dry Storage Canister with Hybrid Heat Pipes

    International Nuclear Information System (INIS)

    Jeong, Yeong Shin; Bang, In Cheol

    2016-01-01

    Dry storage uses the gas or air as coolant within sealed canister with neutron shielding materials. Dry storage system for spent fuel is regarded as relatively safe and emits little radioactive waste for the storage, but it showed that the storage capacity and overall safety of dry cask needs to be enhanced for the dry storage cask for LWR in Korea. For safety enhancement of dry cask, previous studies of our group firstly suggested the passive cooling system with heat pipes for LWR spent fuel dry storage metal cask. As an extension, enhanced thermal management systems for the spent fuel dry storage cask for LWR was suggested with hybrid heat pipe concept, and their performances were analyzed in thermal-hydraulic viewpoint in this paper. In this paper, hybrid heat pipe concept for dry storage cask is suggested for thermal management to enhance safety margin. Although current design of dry cask satisfies the design criteria, it cannot be assured to have long term storage period and designed lifetime. Introducing hybrid heat pipe concept to dry storage cask designed without disrupting structural integrity, it can enhance the overall safety characteristics with adequate thermal management to reduce overall temperature as well as criticality control. To evaluate thermal performance of hybrid heat pipe according to its design, CFD simulation was conducted and previous and revised design of hybrid heat pipe was compared in terms of temperature inside canister

  15. Role of boundary plasma in lower-hybrid-frequency heating of a tokamak

    International Nuclear Information System (INIS)

    Uehara, Kazuya; Yamamoto, Takumi; Fujii, Tsuneyuki

    1982-01-01

    Boundary plasma of a circular tokamak has been investigated by means of electrostatic probes during lower-hybrid heating. The reflection coefficient is affected by the density gradient in front of the launcher. An effective ion heating is performed in the main plasma region when the boundary electron temperature is relatively high enough to suppress the parametric decay instabilities. The simultaneous injection of neutral beams as well as the lower-hybrid wave brings the suppression of instabilities with increase of the electron temperature coming from the neutral beam heating. (author)

  16. A novel circuit topology of modified switched boost hybrid resonant inverter fitted induction heating equipment

    Directory of Open Access Journals (Sweden)

    Bhattacharya Ananyo

    2016-12-01

    Full Text Available A novel circuit topology of modified switched boost high frequency hybrid resonant inverter fitted induction heating equipment is presented in this paper for efficient induction heating. Recently, induction heating technique is becoming very popular for both domestic and industrial purposes because of its high energy efficiency and controllability. Generally in induction heating, a high frequency alternating magnetic field is required to induce the eddy currents in the work piece. High frequency resonant inverters are incorporated in induction heating equipment which produce a high frequency alternating magnetic field surrounding the coil. Previously this high frequency alternating magnetic field was produced by voltage source inverters. But VSIs have several demerits. So, in this paper, a new scheme of modified switched boost high frequency hybrid resonant inverter fitted induction heating equipment has been depicted which enhances the energy efficiency and controllability and the same is validated by PSIM.

  17. Thermochemical Storage of Middle Temperature Wasted Heat by Functionalized C/Mg(OH2 Hybrid Materials

    Directory of Open Access Journals (Sweden)

    Emanuela Mastronardo

    2017-01-01

    Full Text Available For the thermochemical performance implementation of Mg(OH2 as a heat storage medium, several hybrid materials have been investigated. For this study, high-performance hybrid materials have been developed by exploiting the authors’ previous findings. Expanded graphite (EG/carbon nanotubes (CNTs-Mg(OH2 hybrid materials have been prepared through Mg(OH2 deposition-precipitation over functionalized, i.e., oxidized, or un-functionalized EG or CNTs. The heat storage performances of the carbon-based hybrid materials have been investigated through a laboratory-scale experimental simulation of the heat storage/release cycles, carried out by a thermogravimetric apparatus. This study offers a critical evaluation of the thermochemical performances of developed materials through their comparison in terms of heat storage and output capacities per mass and volume unit. It was demonstrated that both EG and CNTs improves the thermochemical performances of the storage medium in terms of reaction rate and conversion with respect to pure Mg(OH2. With functionalized EG/CNTs-Mg(OH2, (i the potential heat storage and output capacities per mass unit of Mg(OH2 have been completely exploited; and (ii higher heat storage and output capacities per volume unit were obtained. That means, for technological applications, as smaller volume at equal stored/released heat.

  18. Investigation of ammonia/water hybrid absorption/compression heat pumps for heat supply temperatures above 100 °C

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Reinholdt, Lars; Markussen, Wiebke Brix

    2014-01-01

    The hybrid absorption/compression heat pump (HACHP) using ammonia-water as working fluid is a promising technology for development of a high temperature industrial heat pump. This is due to two properties inherent to the use of zeotropic mixtures: non-isothermal phase change and reduced vapour...... using these components. A technically and economically feasible solution is defined as one that satisfies constraints on the coefficient of performance (COP), low and high pressure, compressor discharge temperature and volumetric heat capacity. The ammonia mass fraction of the rich solution...

  19. Pressurized Hybrid Heat Pipe for Passive IN-Core Cooling System (PINCs) in Advanced Nuclear Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyung Mo; Bang, In Cheol [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

    2016-05-15

    The representative operating limit of the thermosyphon heat pipe is flooding limit that arises from the countercurrent flow of vapor and liquid. The effect of difference between wetted perimeter and heated perimeter on the flooding limit of the thermosyphons has not been studied; despite the effect of cross-sectional area of the vapor path on the heat transfer characteristics of thermosyphons have been studied. Additionally, the hybrid heat pipe must operate at the high temperature and high pressure environment because it will be inserted to the active core to remove the decay heat. However, the previously studied heat pipes operated below the atmospheric pressure. Therefore, the effect of the unique geometry for hybrid heat pipe and operating pressure on the heat transfer characteristics including the flooding limit of hybrid heat pipe was experimentally measured. Hybrid heat pipe as a new conceptual decay heat removal device was proposed. For the development of hybrid heat pipe operating at high temperature and high pressure conditions, the pressurized hybrid heat pipe was prepared and the thermal performances including operation limits of hybrid heat pipe were experimentally measured. Followings were obtained: (1) As operating pressure of the heat pipe increases, the evaporation heat transfer coefficient increases due to heat transfer with convective pool boiling mode. (2) Non-condensable gas charged in the test section for the pressurization lowered the condensation heat transfer by impeding the vapor flow to the condenser. (3) The deviations between experimentally measured flooding limits for hybrid heat pipes and the values from correlation for annular thermosyphon were observed.

  20. Performance of a Solar Heating System with Photovoltaic Thermal Hybrid Collectors and Heat Pump

    DEFF Research Database (Denmark)

    Dannemand, Mark; Furbo, Simon; Perers, Bengt

    2017-01-01

    . When the solar collectors are unable to supply the heat demand an auxiliary heat source is used. Heat pumps can generate this heat. Liquid/water heat pumps have better performance than air/water heat pumps in cold climates but requires installation of a tubing system for the cold side of the heat pump....... The tubes are typically placed in the ground, requires a significant land area and increase the installation cost. A new system design of a solar heating system with two storage tanks and a liquid/water heat pump is presented. The system consists of PVT collectors that generate both heat and electricity......The energy consumption in buildings accounts for a large part of the World’s CO2 emissions. Much energy is used for appliances, domestic hot water preparation and space heating. In solar heating systems, heat is captured by solar collectors when the sun is shining and used for heating purposes...

  1. Experimental Study on Compression/Absorption High-Temperature Hybrid Heat Pump with Natural Refrigerant Mixture

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji Young; Park, Seong Ryong; Baik, Young Jin; Chang, Ki Chang; Ra, Ho Sang; Kim, Min Sung [Korea Institute of Energy Research, Daejeon (Korea, Republic of); Kim, Yong Chan [Korea University, Seoul (Korea, Republic of)

    2011-12-15

    This research concerns the development of a compression/absorption high-temperature hybrid heat pump that uses a natural refrigerant mixture. Heat pumps based on the compression/absorption cycle offer various advantages over conventional heat pumps based on the vapor compression cycle, such as large temperature glide, temperature lift, flexible operating range, and capacity control. In this study, a lab-scale prototype hybrid heat pump was constructed with a two-stage compressor, absorber, desorber, desuperheater, solution heat exchanger, solution pump, liquid/vapor separator, and rectifier as the main components. The hybrid heat pump system operated at 10-kW-class heating capacity producing hot water whose temperature was more than 90 .deg. C when the heat source and sink temperatures were 50 .deg. C. Experiments with various NH{sub 3}/H{sub 2}O mass fractions and compressor/pump circulation ratios were performed on the system. From the study, the system performance was optimized at a specific NH{sub 3} concentration.

  2. Recovery act. Development of design and simulation tool for hybrid geothermal heat pump system

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shaojie [ClimateMaster, Inc., Oklahoma City, OK (United States); Ellis, Dan [ClimateMaster, Inc., Oklahoma City, OK (United States)

    2014-05-29

    The ground source heat pump (GSHP) system is one of the most energy efficient HVAC technologies in the current market. However, the heat imbalance may degrade the ability of the ground loop heat exchanger (GLHX) to absorb or reject heat. The hybrid GSHP system, which combines a geothermal well field with a supplemental boiler or cooling tower, can balance the loads imposed on the ground loop heat exchangers to minimize its size while retaining superior energy efficiency. This paper presents a recent simulation-based study with an intention to compare multiple common control strategies used in hybrid GSHP systems, including fixed setpoint, outside air reset, load reset, and wetbulb reset. A small office in Oklahoma City conditioned by a hybrid GSHP system was simulated with the latest version of eQUEST 3.7[1]. The simulation results reveal that the hybrid GSHP system has the excellent capability to meet the cooling and heating setpoints during the occupied hours, balance thermal loads on the ground loop, as well as improve the thermal comfort of the occupants with the undersized well field.

  3. Extension of hybrid micro-depletion model for decay heat calculation in the DYN3D code

    International Nuclear Information System (INIS)

    Bilodid, Yurii; Fridman, Emil; Shwageraus, E.

    2017-01-01

    This work extends the hybrid micro-depletion methodology, recently implemented in DYN3D, to the decay heat calculation by accounting explicitly for the heat contribution from the decay of each nuclide in the fuel.

  4. Extension of hybrid micro-depletion model for decay heat calculation in the DYN3D code

    Energy Technology Data Exchange (ETDEWEB)

    Bilodid, Yurii; Fridman, Emil [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Reactor Safety; Kotlyar, D. [Georgia Institute of Technology, Atlanta, GA (United States); Shwageraus, E. [Cambridge Univ. (United Kingdom)

    2017-06-01

    This work extends the hybrid micro-depletion methodology, recently implemented in DYN3D, to the decay heat calculation by accounting explicitly for the heat contribution from the decay of each nuclide in the fuel.

  5. Development of hybrid solar-assisted cooling/heating system

    KAUST Repository

    Huang, B.J.; Wu, J.H.; Hsu, H.Y.; Wang, J.H.

    2010-01-01

    A solar-assisted ejector cooling/heating system (SACH) was developed in this study. The SACH combines a pump-less ejector cooling system (ECS) with an inverter-type heat pump (R22) and is able to provide a stable capacity for space cooling. The ECS is driven by solar heat and is used to cool the condenser of the R22 heat pump to increase its COP and reduce the energy consumption of the compressor by regulating the rotational speed of the compressor through a control system. In a complete SACH system test run at outdoor temperature 35 °C, indoor temperature 25 °C and compressor speed 20-80 Hz, and the ECS operating at generator temperature 90 °C and condensing temperature 37 °C, the corresponding condensing temperature of the heat pump in the SACH is 24.5-42 °C, cooling capacity 1.02-2.44 kW, input power 0.20-0.98 kW, and cooling COPc 5.11-2.50. This indicates that the use of ECS in SACH can effectively reduce the condensing temperature of the heat pump by 12.6-7.3 °C and reduce the power consumption by 81.2-34.5%. The SACH can also supply heat from the heat pump. At ambient temperature from 5 °C to 35 °C, the heating COPh is in the range 2.0-3.3. © 2010 Elsevier Ltd. All rights reserved.

  6. Development of hybrid solar-assisted cooling/heating system

    KAUST Repository

    Huang, B.J.

    2010-08-01

    A solar-assisted ejector cooling/heating system (SACH) was developed in this study. The SACH combines a pump-less ejector cooling system (ECS) with an inverter-type heat pump (R22) and is able to provide a stable capacity for space cooling. The ECS is driven by solar heat and is used to cool the condenser of the R22 heat pump to increase its COP and reduce the energy consumption of the compressor by regulating the rotational speed of the compressor through a control system. In a complete SACH system test run at outdoor temperature 35 °C, indoor temperature 25 °C and compressor speed 20-80 Hz, and the ECS operating at generator temperature 90 °C and condensing temperature 37 °C, the corresponding condensing temperature of the heat pump in the SACH is 24.5-42 °C, cooling capacity 1.02-2.44 kW, input power 0.20-0.98 kW, and cooling COPc 5.11-2.50. This indicates that the use of ECS in SACH can effectively reduce the condensing temperature of the heat pump by 12.6-7.3 °C and reduce the power consumption by 81.2-34.5%. The SACH can also supply heat from the heat pump. At ambient temperature from 5 °C to 35 °C, the heating COPh is in the range 2.0-3.3. © 2010 Elsevier Ltd. All rights reserved.

  7. Conceptual study of lower hybrid frequency heating of the J.E.T. plasma

    International Nuclear Information System (INIS)

    Tonon, G.; Bernard, M.; Brambilla, M.

    1981-04-01

    The aim of this report is to bring up the conclusions of the conceptual study of the J.E.T. plasma heating by lower hybrid waves. While giving an overall view of potential use for lower hybrid heating (LHH) in the J.E.T. plasma, this study deals more specificaly with the following concerns: up-to-date status of LHH theory and experiment; the physics of LHH on J.E.T.: RF requirements and expected results from numerical computations; the J.E.T. LHH coupling structure; the 10 MW RF generator; the associated RF diagnostics; the time schedule and the cost estimates

  8. Thermoeconomic Analysis of Hybrid Power Plant Concepts for Geothermal Combined Heat and Power Generation

    Directory of Open Access Journals (Sweden)

    Florian Heberle

    2014-07-01

    Full Text Available We present a thermo-economic analysis for a low-temperature Organic Rankine Cycle (ORC in a combined heat and power generation (CHP case. For the hybrid power plant, thermal energy input is provided by a geothermal resource coupled with the exhaust gases of a biogas engine. A comparison to alternative geothermal CHP concepts is performed by considering variable parameters like ORC working fluid, supply temperature of the heating network or geothermal water temperature. Second law efficiency as well as economic parameters show that hybrid power plants are more efficient compared to conventional CHP concepts or separate use of the energy sources.

  9. Hybrid Geothermal Heat Pumps for Cooling Telecommunications Data Centers

    Energy Technology Data Exchange (ETDEWEB)

    Beckers, Koenraad J [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Zurmuhl, David P. [Cornell University; Lukawski, Maciej Z. [Cornell University; Aguirre, Gloria A. [Cornell University; Schnaars, George P. [Cornell University; Anderson, C. Lindsay [Cornell University; Tester, Jefferson W. [Cornell University

    2018-02-14

    The technical and economic performance of geothermal heat pump (GHP) systems supplying year-round cooling to representative small data centers with cooling loads less than 500 kWth were analyzed and compared to air-source heat pumps (ASHPs). A numerical model was developed in TRNSYS software to simulate the operation of air-source and geothermal heat pumps with and without supplementary air cooled heat exchangers - dry coolers (DCs). The model was validated using data measured at an experimental geothermal system installed in Ithaca, NY, USA. The coefficient of performance (COP) and cooling capacity of the GHPs were calculated over a 20-year lifetime and compared to the performance of ASHPs. The total cost of ownership (TCO) of each of the cooling systems was calculated to assess its economic performance. Both the length of the geothermal borehole heat exchangers (BHEs) and the dry cooler temperature set point were optimized to minimize the TCO of the geothermal systems. Lastly, a preliminary analysis of the performance of geothermal heat pumps for cooling dominated systems was performed for other locations including Dallas, TX, Sacramento, CA, and Minneapolis, MN.

  10. Electron heating using lower hybrid waves in the PLT tokamak

    International Nuclear Information System (INIS)

    Bell, R.E.; Bernabei, S.; Cavallo, A.; Chu, T.K.; Luce, T.; Motley, R.; Ono, M.; Stevens, J.; von Goeler, S.

    1987-06-01

    Lower hybrid waves with a narrow high velocity wave spectrum have been used to achieve high central electron temperatures in a tokamak plasma. Waves with a frequency of 2.45 GHz launched by a 16-waveguide grill at a power level less than 600 kW were used to increase the central electron temperature of the PLT plasma from 2.2 keV to 5 keV. The magnitude of the temperature increase depends strongly on the phase difference between the waveguides and on the direction of the launched wave. A reduction in the central electron thermal diffusivity is associated with the peaked electron temperature profiles of lower hybrid current-driven plasmas. 16 refs

  11. Calculation of heat fluxes induced by radio frequency heating on the actively cooled protections of ion cyclotron resonant heating (ICRH) and lower hybrid (LH) antennas in Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Ritz, G., E-mail: Guillaume.ritz@gmail.com [CEA, Institut de la Recherche sur la Fusion Magnétique (IRFM), 13108 Saint Paul-lez-Durance (France); Corre, Y., E-mail: Yann.corre@cea.fr [CEA, Institut de la Recherche sur la Fusion Magnétique (IRFM), 13108 Saint Paul-lez-Durance (France); Rault, M.; Missirlian, M. [CEA, Institut de la Recherche sur la Fusion Magnétique (IRFM), 13108 Saint Paul-lez-Durance (France); Portafaix, C. [ITER Organization, Route de Vinon-sur-Verdon, 13115 Saint Paul-lez-Durance (France); Martinez, A.; Ekedahl, A.; Colas, L.; Guilhem, D.; Salami, M.; Loarer, T. [CEA, Institut de la Recherche sur la Fusion Magnétique (IRFM), 13108 Saint Paul-lez-Durance (France)

    2013-10-15

    Highlights: ► The heat flux generated by radiofrequency (RF) heating was calculated using Tore Supra's heating antennas. ► The highest heat flux value, generated by ions accelerated in RF-rectified sheath potentials, was 5 MW/m{sup 2}. ► The heat flux on the limiters of antennas was in the same order of magnitude as that on the toroidal pumping limiter. -- Abstract: Lower hybrid current drive (LHCD) and ion cyclotron resonance heating (ICRH) are recognized as important auxiliary heating and current drive methods for present and next step fusion devices. However, these radio frequency (RF) systems generate a heat flux up to several MW/m{sup 2} on the RF antennas during plasma operation. This paper focuses on the determination of the heat flux deposited on the lateral protections of the RF antennas in Tore Supra. The heat flux was calculated by finite element method (FEM) using a model of the lateral protection. The FEM calculation was based on surface temperature measurements using infrared cameras monitoring the RF antennas. The heat flux related to the acceleration of electrons in front of the LHCD grills (LHCD active) and to the acceleration of ions in RF-rectified sheath potentials (ICRH active) were calculated. Complementary results on the heat flux related to fast ions (ICRH active with a relatively low magnetic field) are also reported in this paper.

  12. Fast ion profiles during neutral beam and lower hybrid heating

    International Nuclear Information System (INIS)

    Heidbrink, W.W.; Strachan, J.D.; Bell, R.E.; Cavallo, A.; Motley, R.; Schilling, G.; Stevens, J.; Wilson, J.R.

    1985-07-01

    Profiles of the d(d,p)t fusion reaction are measured in the PLT tokamak using an array of collimated 3 MeV proton detectors. During deuterium neutral beam injection, the emission profile indicates that the beam deposition is at least as narrow as predicted by a bounce-averaged Fokker-Planck code. The fast ion tail formed by lower hybrid waves (at densities above the critical density for current drive) also peaks strongly near the magnetic axis

  13. Gas Turbine/Solar Parabolic Trough Hybrid Design Using Molten Salt Heat Transfer Fluid: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Turchi, C. S.; Ma, Z.

    2011-08-01

    Parabolic trough power plants can provide reliable power by incorporating either thermal energy storage (TES) or backup heat from fossil fuels. This paper describes a gas turbine / parabolic trough hybrid design that combines a solar contribution greater than 50% with gas heat rates that rival those of natural gas combined-cycle plants. Previous work illustrated benefits of integrating gas turbines with conventional oil heat-transfer-fluid (HTF) troughs running at 390?C. This work extends that analysis to examine the integration of gas turbines with salt-HTF troughs running at 450 degrees C and including TES. Using gas turbine waste heat to supplement the TES system provides greater operating flexibility while enhancing the efficiency of gas utilization. The analysis indicates that the hybrid plant design produces solar-derived electricity and gas-derived electricity at lower cost than either system operating alone.

  14. Majority ion heating near the ion-ion hybrid layer in tokamaks

    International Nuclear Information System (INIS)

    Phillips, C.K.; Hosea, J.C.; Ignat, D.; Majeski, R.; Rogers, J.H.; Schilling, G.; Wilson, J.R.

    1995-08-01

    Efficient direct majority ion heating in a deuterium-tritium (D-T) reactor-grade plasma via absorption of fast magnetosonic waves in the ion cyclotron range of frequencies (ICRF) is discussed. Majority ion heating results from resonance overlap between the cyclotron layers and the D-T ion-ion hybrid layer in hot, dense plasmas for fast waves launched with high parallel wavenumbers. Analytic and numerical models are used to explore the regime in ITER plasmas

  15. Lower hybrid heating data on the Wega experiment revisited using ion stochastic heating and electron Landau damping theories

    International Nuclear Information System (INIS)

    Gormezano, C.; Hess, W.; Ichtchenko, G.

    1980-07-01

    The already obtained data on the Wega Tokamak by lower hybrid heating (f=500 MHz - Psub(HF)=130 KW) are revisited in the light of recent theories on ion stochastic heating and quasi-linear electron Landau damping. It is possible to correctly estimate with these theories the fast ion mean energy, the H.F. power density coupled to the ions and that coupled to the electrons. The values of the parallel index of refraction, Nsub(//), which are necessary to obtain a good quantitative agreement between experiment and theoretical estimates, are the same for the ions and for the electrons, even though at higher values than expected

  16. Correlation of radiation dose and heart rate in dual-source computed tomography coronary angiography.

    Science.gov (United States)

    Laspas, Fotios; Tsantioti, Dimitra; Roussakis, Arkadios; Kritikos, Nikolaos; Efthimiadou, Roxani; Kehagias, Dimitrios; Andreou, John

    2011-04-01

    Computed tomography coronary angiography (CTCA) has been widely used since the introduction of 64-slice scanners and dual-source CT technology, but the relatively high radiation dose remains a major concern. To evaluate the relationship between radiation exposure and heart rate (HR), in dual-source CTCA. Data from 218 CTCA examinations, performed with a dual-source 64-slices scanner, were statistically evaluated. Effective radiation dose, expressed in mSv, was calculated as the product of the dose-length product (DLP) times a conversion coefficient for the chest (mSv = DLPx0.017). Heart rate range and mean heart rate, expressed in beats per minute (bpm) of each individual during CTCA, were also provided by the system. Statistical analysis of effective dose and heart rate data was performed by using Pearson correlation coefficient and two-sample t-test. Mean HR and effective dose were found to have a borderline positive relationship. Individuals with a mean HR >65 bpm observed to receive a statistically significant higher effective dose as compared to those with a mean HR ≤65 bpm. Moreover, a strong correlation between effective dose and variability of HR of more than 20 bpm was observed. Dual-source CT scanners are considered to have the capability to provide diagnostic examinations even with high HR and arrhythmias. However, it is desirable to keep the mean heart rate below 65 bpm and heart rate fluctuation less than 20 bpm in order to reduce the radiation exposure.

  17. Hybrid Model of Inhomogeneous Solar Wind Plasma Heating by Alfven Wave Spectrum: Parametric Studies

    Science.gov (United States)

    Ofman, L.

    2010-01-01

    Observations of the solar wind plasma at 0.3 AU and beyond show that a turbulent spectrum of magnetic fluctuations is present. Remote sensing observations of the corona indicate that heavy ions are hotter than protons and their temperature is anisotropic (T(sub perpindicular / T(sub parallel) >> 1). We study the heating and the acceleration of multi-ion plasma in the solar wind by a turbulent spectrum of Alfvenic fluctuations using a 2-D hybrid numerical model. In the hybrid model the protons and heavy ions are treated kinetically as particles, while the electrons are included as neutralizing background fluid. This is the first two-dimensional hybrid parametric study of the solar wind plasma that includes an input turbulent wave spectrum guided by observation with inhomogeneous background density. We also investigate the effects of He++ ion beams in the inhomogeneous background plasma density on the heating of the solar wind plasma. The 2-D hybrid model treats parallel and oblique waves, together with cross-field inhomogeneity, self-consistently. We investigate the parametric dependence of the perpendicular heating, and the temperature anisotropy in the H+-He++ solar wind plasma. It was found that the scaling of the magnetic fluctuations power spectrum steepens in the higher-density regions, and the heating is channeled to these regions from the surrounding lower-density plasma due to wave refraction. The model parameters are applicable to the expected solar wind conditions at about 10 solar radii.

  18. Modelling and simulation of a hybrid solar heating system for greenhouse applications using Matlab/Simulink

    International Nuclear Information System (INIS)

    Kıyan, Metin; Bingöl, Ekin; Melikoğlu, Mehmet; Albostan, Ayhan

    2013-01-01

    Highlights: • Matlab/Simulink modelling of a solar hybrid greenhouse. • Estimation of greenhouse gas emission reductions. • Feasibility and cost analysis of the system. - Abstract: Solar energy is a major renewable energy source and hybrid solar systems are gaining increased academic and industrial attention due to the unique advantages they offer. In this paper, a mathematical model has been developed to investigate the thermal behavior of a greenhouse heated by a hybrid solar collector system. This hybrid system contains an evacuated tube solar heat collector unit, an auxiliary fossil fuel heating unit, a hot water storage unit, control and piping units. A Matlab/Simulink based model and software has been developed to predict the storage water temperature, greenhouse indoor temperature and the amount of auxiliary fuel, as a function of various design parameters of the greenhouse such as location, dimensions, and meteorological data of the region. As a case study, a greenhouse located in Şanlıurfa/Turkey has been simulated based on recent meteorological data and aforementioned hybrid system. The results of simulations performed on an annual basis indicate that revising the existing fossil fuel system with the proposed hybrid system, is economically feasible for most cases, however it requires a slightly longer payback period than expected. On the other hand, by reducing the greenhouse gas emissions significantly, it has a considerable positive environmental impact. The developed dynamic simulation method can be further used for designing heating systems for various solar greenhouses and optimizing the solar collector and thermal storage sizes

  19. On the application of Chimera/unstructured hybrid grids for conjugate heat transfer

    Science.gov (United States)

    Kao, Kai-Hsiung; Liou, Meng-Sing

    1995-01-01

    A hybrid grid system that combines the Chimera overset grid scheme and an unstructured grid method is developed to study fluid flow and heat transfer problems. With the proposed method, the solid structural region, in which only the heat conduction is considered, can be easily represented using an unstructured grid method. As for the fluid flow region external to the solid material, the Chimera overset grid scheme has been shown to be very flexible and efficient in resolving complex configurations. The numerical analyses require the flow field solution and material thermal response to be obtained simultaneously. A continuous transfer of temperature and heat flux is specified at the interface, which connects the solid structure and the fluid flow as an integral system. Numerical results are compared with analytical and experimental data for a flat plate and a C3X cooled turbine cascade. A simplified drum-disk system is also simulated to show the effectiveness of this hybrid grid system.

  20. The numerical simulation of heat transfer during a hybrid laser-MIG welding using equivalent heat source approach

    Science.gov (United States)

    Bendaoud, Issam; Matteï, Simone; Cicala, Eugen; Tomashchuk, Iryna; Andrzejewski, Henri; Sallamand, Pierre; Mathieu, Alexandre; Bouchaud, Fréderic

    2014-03-01

    The present study is dedicated to the numerical simulation of an industrial case of hybrid laser-MIG welding of high thickness duplex steel UR2507Cu with Y-shaped chamfer geometry. It consists in simulation of heat transfer phenomena using heat equivalent source approach and implementing in finite element software COMSOL Multiphysics. A numerical exploratory designs method is used to identify the heat sources parameters in order to obtain a minimal required difference between the numerical results and the experiment which are the shape of the welded zone and the temperature evolution in different locations. The obtained results were found in good correspondence with experiment, both for melted zone shape and thermal history.

  1. Hybrid utilization of solar energy. Part 2. Performance analyses of heating system with air hybrid collector; Taiyo energy no hybrid riyo ni kansuru kenkyu. 2. Kuki shunetsu hybrid collector wo mochiita danbo system no seino hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Yoshinaga, M; Okumiya, M [Nagoya University, Nagoya (Japan)

    1996-10-27

    For the effective utilization of solar energy at houses, a heating system using an air hybrid collector (capable of simultaneously performing heat collection and photovoltaic power generation). As the specimen house, a wooden house of a total floor area of 120m{sup 2} was simulated. Collected air is fanned into a crushed stone heat accumulator (capable of storing one day`s collection) or into a living room. The output of solar cell arrays is put into a heat pump (capable of handling a maximum hourly load of 36,327kJ/h) via an inverter so as to drive the fan (corresponding to average insolation on the heat collecting plate of 10.7MJ/hm{sup 2} and heat collecting efficiency of 40%), and shortage in power if any is supplied from the system interconnection. A hybrid collector, as compared with the conventional air collector, is lower in thermal efficiency but the merit that it exhibits with respect to power generation is far greater than what is needed to counterbalance the demerit. When the hybrid system is in heating operation, there is an ideal heat cycle of collection, accumulation, and radiation when the load is light, but the balance between accumulation and radiation is disturbed when the load is heavy. 4 refs., 8 figs., 3 tabs.

  2. Lower hybrid resonance heating of the JET plasma

    International Nuclear Information System (INIS)

    Brambilla, M.; Lallia, P.; Nguyen Trong, K.

    1975-10-01

    A preliminary proposition is presented to apply high power L.H.R. heating to the JET plasma, using a phased weveguide array (the Grill). The frequency is first choosen in order to locate the energy absorption region well within the plasma. The theory of the grill as a launching structure is then used to define the most appropriate Grill parameters compatible with the access available on the JET. Finally, a source and circuit realization capable of launching 10MW to the plasma is proposed [fr

  3. Pool-Boiling Heat-Transfer Enhancement on Cylindrical Surfaces with Hybrid Wettable Patterns.

    Science.gov (United States)

    Kumar C S, Sujith; Chang, Yao Wen; Chen, Ping-Hei

    2017-04-10

    In this study, pool-boiling heat-transfer experiments were performed to investigate the effect of the number of interlines and the orientation of the hybrid wettable pattern. Hybrid wettable patterns were produced by coating superhydrophilic SiO2 on a masked, hydrophobic, cylindrical copper surface. Using de-ionized (DI) water as the working fluid, pool-boiling heat-transfer studies were conducted on the different surface-treated copper cylinders of a 25-mm diameter and a 40-mm length. The experimental results showed that the number of interlines and the orientation of the hybrid wettable pattern influenced the wall superheat and the HTC. By increasing the number of interlines, the HTC was enhanced when compared to the plain surface. Images obtained from the charge-coupled device (CCD) camera indicated that more bubbles formed on the interlines as compared to other parts. The hybrid wettable pattern with the lowermost section being hydrophobic gave the best heat-transfer coefficient (HTC). The experimental results indicated that the bubble dynamics of the surface is an important factor that determines the nucleate boiling.

  4. Screening of Pearl Millet F1 Hybrids for Heat Tolerance at Early Seedling Stage

    Directory of Open Access Journals (Sweden)

    Ashok Kumar Yadav

    2014-01-01

    Full Text Available Ten pearl millet genotypes selected on the basis of response to supra-optimal temperature tolerance were crossed in a half-diallel mating system. The 45 F1 hybrids produced were tested along with parents for heat tolerance and related traits at seedling stage. Field screening and laboratory screening techniques were simultaneously used for the evaluation of F1 hybrids and their parents. Heat tolerance was measured as seedling thermotolerance index (STI and seed to seedling thermotolerance index (SSTI under field conditions, but membrane thermostability (MTS in the laboratory. The hybrid H77/29-2 × CVJ-2-5-3-1-3 showed highest STI value followed by H77/833-2 × 96AC-93. The genotype H77/833-2 × 96AC-93 had the highest worth for SSTI. These three indices were highly correlated among themselves. STI values were invariably high, whereas SSTI has lower values, as it also covers the effect of under soil mortality (USM. It was seen that the heat tolerance indices STI and SSTI were not showing any perceptible pooled correlation with developmental traits except germination and emergence rate. Based on our results, it could be suggested that membrane thermostability (MTS may be used for screening large number of genotypes. Field based indices STI and SSTI may be used for evaluation of hybrids and varieties before they are released.

  5. Hybrid Ground-Source Heat Pump Installations: Experiences, Improvements, and Tools

    Energy Technology Data Exchange (ETDEWEB)

    Scott Hackel; Amanda Pertzborn

    2011-06-30

    One innovation to ground-source heat pump (GSHP, or GHP) systems is the hybrid GSHP (HyGSHP) system, which can dramatically decrease the first cost of GSHP systems by using conventional technology (such as a cooling tower or a boiler) to meet a portion of the peak heating or cooling load. This work uses three case studies (two cooling-dominated, one heating-dominated) to demonstrate the performance of the hybrid approach. Three buildings were studied for a year; the measured data was used to validate models of each system. The models were used to analyze further improvements to the hybrid approach, and establish that this approach has positive impacts, both economically and environmentally. Lessons learned by those who design and operate the systems are also documented, including discussions of equipment sizing, pump operation, and cooling tower control. Finally, the measured data sets and models that were created during this work are described; these materials have been made freely available for further study of hybrid systems.

  6. GEOTHERMAL / SOLAR HYBRID DESIGNS: USE OF GEOTHERMAL ENERGY FOR CSP FEEDWATER HEATING

    Energy Technology Data Exchange (ETDEWEB)

    Craig Turchi; Guangdong Zhu; Michael Wagner; Tom Williams; Dan Wendt

    2014-10-01

    This paper examines a hybrid geothermal / solar thermal plant design that uses geothermal energy to provide feedwater heating in a conventional steam-Rankine power cycle deployed by a concentrating solar power (CSP) plant. The geothermal energy represents slightly over 10% of the total thermal input to the hybrid plant. The geothermal energy allows power output from the hybrid plant to increase by about 8% relative to a stand-alone CSP plant with the same solar-thermal input. Geothermal energy is converted to electricity at an efficiency of 1.7 to 2.5 times greater than would occur in a stand-alone, binary-cycle geothermal plant using the same geothermal resource. While the design exhibits a clear advantage during hybrid plant operation, the annual advantage of the hybrid versus two stand-alone power plants depends on the total annual operating hours of the hybrid plant. The annual results in this draft paper are preliminary, and further results are expected prior to submission of a final paper.

  7. Coronary artery anomalies in adults: imaging at dual source CT coronary angiography

    International Nuclear Information System (INIS)

    Laspas, Fotios; Roussakis, Arkadios; Mourmouris, Christos; Kritikos, Nikolaos; Efthimiadou, Roxani; Andreou, John

    2013-01-01

    Congenital abnormalities of the coronary arteries have an incidence of 1%, and most of these are benign. However, a small number are associated with myocardial ischaemia and sudden death. Various imaging modalities are available for coronary artery assessment. Recently, multi-detector CT has emerged as an accurate diagnostic tool for defining coronary artery anomalies. The purpose of this pictorial essay is to review the dual source CT appearance of congenital anomalies of the coronary arteries in adults.

  8. Correlation of radiation dose and heart rate in dual-source computed tomography coronary angiography

    International Nuclear Information System (INIS)

    Laspas, Fotios; Roussakis, Arkadios; Kritikos, Nikolaos; Efthimiadou, Roxani; Kehagias, Dimitrios; Andreou, John; Tsantioti, Dimitra

    2011-01-01

    Background: Computed tomography coronary angiography (CTCA) has been widely used since the introduction of 64-slice scanners and dual-source CT technology, but the relatively high radiation dose remains a major concern. Purpose: To evaluate the relationship between radiation exposure and heart rate (HR), in dual-source CTCA. Material and Methods: Data from 218 CTCA examinations, performed with a dual-source 64-slices scanner, were statistically evaluated. Effective radiation dose, expressed in mSv, was calculated as the product of the dose-length product (DLP) times a conversion coefficient for the chest (mSv = DLPx0.017). Heart rate range and mean heart rate, expressed in beats per minute (bpm) of each individual during CTCA, were also provided by the system. Statistical analysis of effective dose and heart rate data was performed by using Pearson correlation coefficient and two-sample t-test. Results: Mean HR and effective dose were found to have a borderline positive relationship. Individuals with a mean HR >65 bpm observed to receive a statistically significant higher effective dose as compared to those with a mean HR =65 bpm. Moreover, a strong correlation between effective dose and variability of HR of more than 20 bpm was observed. Conclusion: Dual-source CT scanners are considered to have the capability to provide diagnostic examinations even with high HR and arrhythmias. However, it is desirable to keep the mean heart rate below 65 bpm and heart rate fluctuation less than 20 bpm in order to reduce the radiation exposure

  9. Advanced Waste Heat Recovery Systems within Hybrid Powertrains

    Directory of Open Access Journals (Sweden)

    Albert Boretti

    2018-01-01

    Full Text Available A waste heat recovery system (WHRS is very well known to provide no advantage during the cold start driving cycles, such as the New European Driving Cycle (NEDC, which are used for certification of emissions and assessment of fuel economy. Here, we propose a novel integrated WHRS using the internal combustion engine (ICE coolant passages and an exchanger on the exhaust working as pre-heater / boiler / super-heater of a Rankine cycle. The expander is connected to an electric generator unit (GU, and the pump is connected to an electric motor unit (MU. The vehicle is also fitted with an electric, kinetic energy recovery system (KERS. The expander and condenser are bypassed during the first part of the NEDC when the vehicle covers the four ECE-15 (Economic Commission for Europe - 15 - UDC (Urban Drive Cycle segments where the engine warms-up.  Only after the engine is fully warmed up, during the last part of the NEDC, the extra urban driving cycle (EUDC segment, the expander and condenser are activated to recover part of the coolant and exhaust energy.

  10. On the development of high temperature ammonia-water hybrid absorption-compression heat pumps

    DEFF Research Database (Denmark)

    Jensen, Jonas Kjær; Markussen, Wiebke Brix; Reinholdt, Lars

    2015-01-01

    Ammonia-water hybrid absorption-compression heat pumps (HACHP) are a promising technology for development of ecient high temperature industrial heat pumps. Using 28 bar components HACHPs up to 100 °C are commercially available. Components developed for 50 bar and 140 bar show that these pressure...... limits may be possible to exceed if needed for actual applications. Feasible heat supply temperatures using these component limits are investigated. A feasible solution is defined as one that satisfies constraints on the COP, low and high pressure, compressor discharge temperature, vapour water content...... and volumetric heat capacity. The ammonia mass fraction and the liquid circulation ratio both influence these constraining parameters. The paper investigates feasible combinations of these parameters through the use of a numerical model. 28 bar components allow temperatures up to 111 °C, 50 bar up to 129°C...

  11. Recovery of exhaust waste heat for a hybrid car using steam turbine

    Science.gov (United States)

    Ababatin, Yasser

    A number of car engines operate with an efficiency rate of approximately 22% to 25% [1]. The remainder of the energy these engines generate is wasted through heat escape out of the exhaust pipe. There is now an increasing desire to reuse this heat energy, which would improve the overall efficiency of car engines by reducing their consumption of fuel. Another benefit is that such reuse would minimize harmful greenhouse gases that are emitted into the environment. Therefore, the purpose of this project is to examine how the wasted heat energy can be reused and/or recovered by use of a heat recovery system that would store this energy in a hybrid car battery. Green turbines will be analyzed as a possible solution to recycle the lost energy in a way that will also improve the overall automotive energy efficiency.

  12. Development of the heat treatment system for the 40 T hybrid magnet superconducting outsert.

    Science.gov (United States)

    Chen, W G; Chen, Z M; Chen, Z Y; Huang, P C; He, P; Zhu, J W

    2011-10-01

    The heat treatment of Nb(3)Sn coil with the glass fabric insulation is one of the key and critical processes for the outsert solenoids of the 40 T hybrid magnet, which could be wound with cable-in-conduit conductors using the insulation-wind-and-react technique. The manufacturing of the large vertical type vacuum/Ar atmosphere-protection heat treatment system has been completed and recently installed in the High Magnetic Filed Laboratory, Chinese Academy of Sciences. The heat treatment system composed mainly the furnace, the purging gas supply system, the control system, the gas impurities monitoring system, and so on. At present, the regulation and testing of the heat treatment system has been successfully finished, and all of technical parameters meet or exceed specifications.

  13. Lower hybrid heating associated with mode conversion on the Wisconsin octupole

    International Nuclear Information System (INIS)

    Owens, T.L.

    1979-08-01

    This thesis addresses the following key issues in the lower hybrid frequency range: 1. What are the importent physics aspects of wave propagation and heating in an experimental situation. 2. How effective is plasma heating in the complex magnetic field configuration of the octupole. Experimental work is accomplished by launching 1-10ms pulses of up to 40kW of radio frequency power at 140MHz corresponding to the hot plasma lower hybrid resonance in the octupole. A diploe antenna which is moveable radially and is also rotatable couples wave power to the plasma. Coupling efficiencies greater than 95% are achieved by proper antenna placement near the edge of the plasma radial density profile

  14. Lower hybrid heating associated with mode conversion on the Wisconsin toroidal octupole

    International Nuclear Information System (INIS)

    Owens, T.L.; Scharer, J.E.

    1980-09-01

    Wave heating experiments and wave propagation measurements in the lower hybrid range of frequencies are described. A T antenna launches up to 40 kW of wave power at 140 MHz with better than 95% coupling efficiency. Ion temperature increases of ΔT/sub i/ = 37 eV are measured with ΔT/sub parallel//T/sub io/ = 12. Ion heating is strongly localized near the lower hybrid turning point for a peak value of (k/sub parallel//ω)(KT/sub i//m/sub e/)/sup 1/2/ approx. = 0.3 corresponding to an upshifted k/sub parallel/ spectrum. Wavelength measurements indicate that the upshift in k/sub parallel/ occurs in the interior of the plasma. Other wave measurements show the existence of a large amplitude weakly damped fast wave component in addition to the slow wave

  15. Multiwalled Carbon Nanotube Nanofluids Used for Heat Dissipation in Hybrid Green Energy Systems

    Directory of Open Access Journals (Sweden)

    Yi-Hsuan Hung

    2014-01-01

    Full Text Available This study was conducted to characterize carbon nanotube (CNT/water nanofluids (CNWNFs and to apply the nanofluids in a heat-dissipation system of dual green energy sources. CNTs were mixed with water in weight fractions of 0.125%, 0.25%, and 0.5% to produce nanofluids. The thermal conductivity, density, viscosity, and specific heat of the nanofluids were measured. An experimental platform consisting of a simulated dual energy source and a microchip controller was established to evaluate the heat-dissipation performance. Two indices, the heat dissipation enhancement ratio and specific heat dissipation enhancement ratio (SHDER, were defined and calculated. The CNWNFs with a CNT concentration of 0.125 wt.% were used because they exhibited the highest SHDER. The steady-state performance was evaluated at 2 flow rates, 11 hybrid flow ratios, and 3 heating ratios for a total power of 1000 W. The transient behavior of the energy sources at preset optimal temperatures was examined, and the CNWNFs exhibited average increases in stability and heat dissipation efficiency of 36.2% and 5%, respectively, compared with water. This nanofluid heat-dissipation system is expected to be integrated with real dual energy sources in the near future.

  16. Hybrid Heat Pipes for High Heat Flux Spacecraft Thermal Control, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Grooved aluminum/ammonia Constant Conductance Heat Pipes (CCHPs) are the standard for thermal control in zero-gravity. Unfortunately, they are limited in terms of...

  17. Elevated [CO2] magnifies isoprene emissions under heat and improves thermal resistance in hybrid aspen

    OpenAIRE

    Sun, Zhihong; H?ve, Katja; Vislap, Vivian; Niinemets, ?lo

    2013-01-01

    Isoprene emissions importantly protect plants from heat stress, but the emissions become inhibited by instantaneous increase of [CO2], and it is currently unclear how isoprene-emitting plants cope with future more frequent and severe heat episodes under high [CO2]. Hybrid aspen (Populus tremula x Populus tremuloides) saplings grown under ambient [CO2] of 380 ?mol mol?1 and elevated [CO2] of 780 ?mol mol?1 were used to test the hypothesis that acclimation to elevated [CO2] reduces the inhibito...

  18. Numerical and experimental analysis of heat transfer in injector plate of hydrogen peroxide hybrid rocket motor

    Science.gov (United States)

    Cai, Guobiao; Li, Chengen; Tian, Hui

    2016-11-01

    This paper is aimed to analyze heat transfer in injector plate of hydrogen peroxide hybrid rocket motor by two-dimensional axisymmetric numerical simulations and full-scale firing tests. Long-time working, which is an advantage of hybrid rocket motor over conventional solid rocket motor, puts forward new challenges for thermal protection. Thermal environments of full-scale hybrid rocket motors designed for long-time firing tests are studied through steady-state coupled numerical simulations of flow field and heat transfer in chamber head. The motor adopts 98% hydrogen peroxide (98HP) oxidizer and hydroxyl-terminated poly-butadiene (HTPB) based fuel as the propellants. Simulation results reveal that flowing liquid 98HP in head oxidizer chamber could cool the injector plate of the motor. The cooling of 98HP is similar to the regenerative cooling in liquid rocket engines. However, the temperature of the 98HP in periphery portion of the head oxidizer chamber is higher than its boiling point. In order to prevent the liquid 98HP from unexpected decomposition, a thermal protection method for chamber head utilizing silica-phenolics annular insulating board is proposed. The simulation results show that the annular insulating board could effectively decrease the temperature of the 98HP in head oxidizer chamber. Besides, the thermal protection method for long-time working hydrogen peroxide hybrid rocket motor is verified through full-scale firing tests. The ablation of the insulating board in oxygen-rich environment is also analyzed.

  19. Solar-Biomass hybrid system for process heat supply in medium scale hotels in Sri Lanka

    OpenAIRE

    Abeywardana, Asela M.A.J.

    2016-01-01

    This study aimed at evaluating and demonstrating the feasibility of using Concentrated Solar Thermal technology combined with biomass energy technology as a hybrid renewable energy system to supply the process heat requirements in small scale industries in Sri Lanka. Particularly, the focus was to apply the concept to the expanding hotel industry, for covering the thermal energy demand of a medium scale hotel. Solar modules utilize the rooftop area of the building to a valuable application. L...

  20. Non-linear effects and plasma heating by lower-hybrid waves in the Petula tokamak

    International Nuclear Information System (INIS)

    Briand, P.; Dupas, L.; Golovato, S.N.; Singh, C.M.; Melin, G.; Grelot, P.; Legardeur, R.; Zymanski, S.

    1979-01-01

    Lower hybrid waves were excited by a two-waveguide 'grill' (nsub(parallel) approximately 1-10, Esub(grill) approximately 3kVcm -1 , Psub(grill) approximately 5kWcm -2 ) at 1.25GHz, 3ms, 600kW. Plasma heating was observed separately as due to non-linear effects alone as well as to a combination of linear and non-linear mechanisms. (author)

  1. Making use of the energy potential of hybrid heat production from excess green electricity; Energetische Potenziale hybrider Waermeerzeugung aus Oekostrom-Ueberangeboten nutzen

    Energy Technology Data Exchange (ETDEWEB)

    Volkmann, Lukas; Riegebauer, Philipp; Oesterwind, Dieter [Zentrum fuer Innovative Energiesysteme (ZIES), Duesseldorf (Germany); Muench, Wolfram [Energie Baden-Wuerttemberg AG (EnBW), Karlsruhe (Germany)

    2013-06-15

    Convert electricity to heat? Integration with the heat market opens up the option of using excess yields of electricity from renewable resources for hybrid provision of room heating, warm water and process steam. Environmental protection associations such as BUND e.V. (Association for Environmental Protection and Nature Conservation) are demanding a ban on conventional electric heating, but at the same time acknowledge the potential of plants that can flexibly switch between generating heat from fossil fuels and from electricity. Time for a paradigm change.

  2. Photothermally Activated Pyroelectric Polymer Films for Harvesting of Solar Heat with a Hybrid Energy Cell Structure.

    Science.gov (United States)

    Park, Teahoon; Na, Jongbeom; Kim, Byeonggwan; Kim, Younghoon; Shin, Haijin; Kim, Eunkyoung

    2015-12-22

    Photothermal effects in poly(3,4-ethylenedioxythiophene)s (PEDOTs) were explored for pyroelectric conversion. A poled ferroelectric film was coated on both sides with PEDOT via solution casting polymerization of EDOT, to give highly conductive and effective photothermal thin films of PEDOT. The PEDOT films not only provided heat source upon light exposure but worked as electrodes for the output energy from the pyroelectric layer in an energy harvester hybridized with a thermoelectric layer. Compared to a bare thermoelectric system under NIR irradiation, the photothermal-pyro-thermoelectric device showed more than 6 times higher thermoelectric output with the additional pyroelectric output. The photothermally driven pyroelectric harvesting film provided a very fast electric output with a high voltage output (Vout) of 15 V. The pyroelectric effect was significant due to the transparent and high photothermal PEDOT film, which could also work as an electrode. A hybrid energy harvester was assembled to enhance photoconversion efficiency (PCE) of a solar cell with a thermoelectric device operated by the photothermally generated heat. The PCE was increased more than 20% under sunlight irradiation (AM 1.5G) utilizing the transmitted light through the photovoltaic cell as a heat source that was converted into pyroelectric and thermoelectric output simultaneously from the high photothermal PEDOT electrodes. Overall, this work provides a dynamic and static hybrid energy cell to harvest solar energy in full spectral range and thermal energy, to allow solar powered switching of an electrochromic display.

  3. Modelling of combined ICRF and NBI heating in JET hybrid plasmas

    Directory of Open Access Journals (Sweden)

    Gallart Dani

    2017-01-01

    Full Text Available During the 2015-2016 JET campaigns many efforts have been devoted to the exploration of high performance plasma scenarios envisaged for ITER operation. In this paper we model the combined ICRF+NBI heating in selected key hybrid discharges using PION. The antenna frequency was tuned to match the cyclotron frequency of minority hydrogen (H at the center of the tokamak coinciding with the second harmonic cyclotron resonance of deuterium. The modelling takes into account the synergy between ICRF and NBI heating through the second harmonic cyclotron resonance of deuterium beam ions which allows us to assess its impact on the neutron rate RNT. We evaluate the influence of H concentration which was varied in different discharges in order to test their role in the heating performance. According to our modelling, the ICRF enhancement of RNT increases by decreasing the H concentration which increases the ICRF power absorbed by deuterons. We find that in the recent hybrid discharges this ICRF enhancement was in the range of 10-25%. Finally, we extrapolate the results to D-T and find that the best performing hybrid discharges correspond to an equivalent fusion power of ∼7.0 MW in D-T.

  4. Hybrid finite volume/ finite element method for radiative heat transfer in graded index media

    Science.gov (United States)

    Zhang, L.; Zhao, J. M.; Liu, L. H.; Wang, S. Y.

    2012-09-01

    The rays propagate along curved path determined by the Fermat principle in the graded index medium. The radiative transfer equation in graded index medium (GRTE) contains two specific redistribution terms (with partial derivatives to the angular coordinates) accounting for the effect of the curved ray path. In this paper, the hybrid finite volume with finite element method (hybrid FVM/FEM) (P.J. Coelho, J. Quant. Spectrosc. Radiat. Transf., vol. 93, pp. 89-101, 2005) is extended to solve the radiative heat transfer in two-dimensional absorbing-emitting-scattering graded index media, in which the spatial discretization is carried out using a FVM, while the angular discretization is by a FEM. The FEM angular discretization is demonstrated to be preferable in dealing with the redistribution terms in the GRTE. Two stiff matrix assembly schemes of the angular FEM discretization, namely, the traditional assembly approach and a new spherical assembly approach (assembly on the unit sphere of the solid angular space), are discussed. The spherical assembly scheme is demonstrated to give better results than the traditional assembly approach. The predicted heat flux distributions and temperature distributions in radiative equilibrium are determined by the proposed method and compared with the results available in other references. The proposed hybrid FVM/FEM method can predict the radiative heat transfer in absorbing-emitting-scattering graded index medium with good accuracy.

  5. Hybrid finite volume/ finite element method for radiative heat transfer in graded index media

    International Nuclear Information System (INIS)

    Zhang, L.; Zhao, J.M.; Liu, L.H.; Wang, S.Y.

    2012-01-01

    The rays propagate along curved path determined by the Fermat principle in the graded index medium. The radiative transfer equation in graded index medium (GRTE) contains two specific redistribution terms (with partial derivatives to the angular coordinates) accounting for the effect of the curved ray path. In this paper, the hybrid finite volume with finite element method (hybrid FVM/FEM) (P.J. Coelho, J. Quant. Spectrosc. Radiat. Transf., vol. 93, pp. 89-101, 2005) is extended to solve the radiative heat transfer in two-dimensional absorbing-emitting-scattering graded index media, in which the spatial discretization is carried out using a FVM, while the angular discretization is by a FEM. The FEM angular discretization is demonstrated to be preferable in dealing with the redistribution terms in the GRTE. Two stiff matrix assembly schemes of the angular FEM discretization, namely, the traditional assembly approach and a new spherical assembly approach (assembly on the unit sphere of the solid angular space), are discussed. The spherical assembly scheme is demonstrated to give better results than the traditional assembly approach. The predicted heat flux distributions and temperature distributions in radiative equilibrium are determined by the proposed method and compared with the results available in other references. The proposed hybrid FVM/FEM method can predict the radiative heat transfer in absorbing-emitting-scattering graded index medium with good accuracy.

  6. Optimal control of a fuel cell/wind/PV/grid hybrid system with thermal heat pump load

    CSIR Research Space (South Africa)

    Sichilalu, S

    2016-10-01

    Full Text Available This paper presents an optimal energy management strategy for a grid-tied photovoltaic–wind-fuel cell hybrid power supply system. The hybrid system meets the load demand consisting of an electrical load and a heat pump water heater supplying thermal...

  7. Convective Heat Transfer in a Pneumatic Hybrid Engine Échange de chaleur convectif dans un moteur hybride pneumatique

    Directory of Open Access Journals (Sweden)

    Brejaud P.

    2011-09-01

    Full Text Available Several previous studies have proven that pneumatic hybridization of an internal combustion engine is a technically viable and cost-efficient alternative to electric hybridization. Because the heat transfer process remains a first order factor while the engine operates in a motored or pneumatic mode without combustion, an accurate instantaneous heat transfer model is required in order to predict the in-cylinder pressure. This study shows that the original Woschni model is not suitable for describing the shape of the measured instantaneous heat flux versus crank angle while the engine operates in a motored pneumatic mode, because of the extinction of tumble motion near Top Dead Center (TDC. A modified form of the Woschni model is therefore proposed here that better describes the instantaneous heat flux during compression and expansion strokes, applicable to pneumatic and motored with fuel cut-off modes. First, the new constant parameter model is identified from experimental measurements performed in various motored mode conditions. Next, the pneumatic supercharged mode without combustion (ignition not performed is investigated with the new model using the same identification values as for the motored mode. This study shows that the modified model remains fully applicable to the supercharged mode, despite of a certainly modified in-cylinder aerodynamic structure created by the opening of the charging valve under a high pressure ratio. Plusieurs études ont déjà montré que le concept d’hybride pneumatique est une alternative techniquement et économiquement viable à l’hybridation électrique. Malgré l’absence de combustion lors d’un fonctionnement en mode entraîné ou pneumatique, les échanges de chaleurs convectifs restent un facteur de premier ordre sur un bilan énergétique. Il faut donc disposer d’un modèle précis d’échange de chaleur instantané afin de prévoir la pression instantanée dans un cylindre du moteur. Cette

  8. Hybrid renewable energy system application for electricity and heat supply of a residential building

    Directory of Open Access Journals (Sweden)

    Nakomčić-Smaragdakis Branka B.

    2016-01-01

    Full Text Available Renewable and distributed energy systems could provide a solution to the burning issue of reliable and clean supply of energy, having in mind current state and future predictions for population growth and fossil fuel scarcity. Hybrid renewable energy systems are novelty in Serbia and warrant further detailed research. The aim of this paper is to analyze the application of renewable energy sources(RES for electricity and heat supply of a typical household in Serbia, as well as the cost-effectiveness of the proposed system. The influence of feed-in tariff change on the value of the investment is analyzed. Small, grid-connected hybrid system (for energy supply of a standard household, consisting of geothermal heat pump for heating/cooling, solar photovoltaic panels and small wind turbine for power supply is analyzed as a case study. System analysis was conducted with the help of RETScreen software. Results of techno-economics analysis have shown that investing in geothermal heat pump and photovoltaic panels is cost-effective, while that is not the case with small wind turbine.

  9. Computer simulations of upper-hybrid and electron cyclotron resonance heating

    International Nuclear Information System (INIS)

    Lin, A.T.; Lin, C.C.

    1983-01-01

    A 2 1/2 -dimensional relativistic electromagnetic particle code is used to investigate the dynamic behavior of electron heating around the electron cyclotron and upper-hybrid layers when an extraordinary wave is obliquely launched from the high-field side into a magnetized plasma. With a large angle of incidence most of the radiation wave energy converts into electrostatic electron Bernstein waves at the upper-hybrid layer. These mode-converted waves propagate back to the cyclotron layer and deposit their energy in the electrons through resonant interactions dominated first by the Doppler broadening and later by the relativistic mass correction. The line shape for both mechanisms has been observed in the simulations. At a later stage, the relativistic resonance effects shift the peak of the temperature profile to the high-field side. The heating ultimately causes the extraordinary wave to be substantially absorbed by the high-energy electrons. The steep temperature gradient created by the electron cyclotron heating eventually reflects a substantial part of the incident wave energy. The diamagnetic effects due to the gradient of the mode-converted Bernstein wave pressure enhance the spreading of the electron heating from the original electron cyclotron layer

  10. CFD analysis of heat transfer performance of graphene based hybrid nanofluid in radiators

    Science.gov (United States)

    Bharadwaj, Bharath R.; Sanketh Mogeraya, K.; Manjunath, D. M.; Rao Ponangi, Babu; Rajendra Prasad, K. S.; Krishna, V.

    2018-04-01

    For Improved performance of an automobile engine, Cooling systems are one of the critical systems that need attention. With increased capacity to carry away large amounts of wasted heat, performance of an engine is increased. Current research on Nano-fluids suggests that they offer higher heat transfer rate compared to that of conventional coolants. Hence this project seeks to investigate the use of hybrid-nanofluids in radiators so as to increase its heat transfer performance. Carboxyl Graphene and Graphene Oxide based nanoparticles were selected due to the very high thermal conductivity of Graphene. System Analysis of the radiator was performed by considering a small part of the whole automobile radiator modelled using SEIMENS NX. CFD analysis was conducted using ANSYS FLUENT® for the nanofluid defined and the increase in effectiveness was compared to that of conventional coolants. Usage of such nanofluids for a fixed cooling requirement in the future can lead to significant downsizing of the radiator.

  11. Allocating resources and products in multi-hybrid multi-cogeneration: What fractions of heat and power are renewable in hybrid fossil-solar CHP?

    International Nuclear Information System (INIS)

    Beretta, Gian Paolo; Iora, Paolo; Ghoniem, Ahmed F.

    2014-01-01

    A general method for the allocation of resources and products in multi-resource/multi-product facilities is developed with particular reference to the important two-resource/two-product case of hybrid fossil and solar/heat and power cogeneration. For a realistic case study, we show how the method allows to assess what fractions of the power and heat should be considered as produced from the solar resource and hence identified as renewable. In the present scenario where the hybridization of fossil power plants by solar-integration is gaining increasing attention, such assessment is of great importance in the fair and balanced development of local energy policies based on granting incentives to renewables resources. The paper extends to the case of two-resource/two-product hybrid cogeneration, as well as to general multi-resource/multi-generation, three of the allocation methods already available for single-resource/two-product cogeneration and for two-resource/single-product hybrid facilities, namely, the ExRR (Exergy-based Reversible-Reference) method, the SRSPR (Single Resource Separate Production Reference) method, and the STALPR (Self-Tuned-Average-Local-Productions-Reference) method. For the case study considered we show that, unless the SRSPR reference efficiencies are constantly updated, the differences between the STALPR and SRSPR methods become important as hybrid and cogeneration plants take up large shares of the local energy production portfolio. - Highlights: • How much of the heat and power in hybrid solar-fossil cogeneration are renewable? • We define and compare three allocation methods for hybrid cogeneration. • Classical and exergy allocation are based on prescribed reference efficiencies. • Adaptive allocation is based on the actual average efficiencies in the local area. • Differences among methods grow as hybrid CHP (heat and power cogeneration) gains large market fractions

  12. Hybrid ground-source heat pump system with active air source regeneration

    International Nuclear Information System (INIS)

    Allaerts, K.; Coomans, M.; Salenbien, R.

    2015-01-01

    Highlights: • A hybrid ground source heat pump system with two separate borefields is modelled. • The maximum underground storage temperature depends on the size of the drycooler. • Drycooler selection curves are given as function of underground storage temperature. • The size of the cold storage is reduced with 47% in the cost optimal configuration. • The cooling seasonal performance factor decreases with reduced storage capacity. - Abstract: Ground-source heat pump systems (GSHP) offer great advantages over traditional heating and cooling installations. However, their applications are limited due to the high initial costs of borehole drilling. One way to avoid these costs is by reducing the size of the borefield, e.g. by combining the system with other renewable energy sources or by using active regeneration to increase the system efficiency. In this paper a hybrid ground-source heat pump system (HGSHP) is analyzed. The borefield is split into a warm part and a cold part, which allows for seasonal thermal-energy storage. Additionally, supplementary drycoolers capture heat during summer and cold during winter. The relationship between the underground storage size and temperature and the drycooler capacity is described, using an office building in Flanders (Belgium) as reference case. Results show that with a HGSHP system a significant borefield size reduction can be achieved without compromising system performance; i.e. for the reference case a reduction of 47% was achieved in the cost-optimal configuration. It is also shown that the cooling seasonal performance factor decreases significantly with underground storage capacity. In addition, the HGSHP can be used to maintain or restore thermal balance in the geothermal source when heating and cooling loads do not match

  13. Imaging phase holdup distribution of three phase flow systems using dual source gamma ray tomography

    International Nuclear Information System (INIS)

    Varma, Rajneesh; Al-Dahhan, Muthanna; O'Sullivan, Joseph

    2008-01-01

    Full text: Multiphase reaction and process systems are used in abundance in the chemical and biochemical industry. Tomography has been successfully employed to visualize the hydrodynamics of multiphase systems. Most of the tomography methods (gamma ray, x-ray and electrical capacitance and resistance) have been successfully implemented for two phase dynamic systems. However, a significant number of chemical and biochemical systems consists of dynamic three phases. Research effort directed towards the development of tomography techniques to image such dynamic system has met with partial successes for specific systems with applicability to limited operating conditions. A dual source tomography scanner has been developed that uses the 661 keV and 1332 keV photo peaks from the 137 Cs and 60 Co for imaging three phase systems. A new approach has been developed and applied that uses the polyenergetic Alternating Minimization (A-M) algorithm, developed by O'Sullivan and Benac (2007), for imaging the holdup distribution in three phases' dynamic systems. The new approach avoids the traditional post image processing approach used to determine the holdup distribution where the attenuation images of the mixed flow obtained from gamma ray photons of two different energies are used to determine the holdup of three phases. In this approach the holdup images are directly reconstructed from the gamma ray transmission data. The dual source gamma ray tomography scanner and the algorithm were validated using a three phase phantom. Based in the validation, three phase holdup studies we carried out in slurry bubble column containing gas liquid and solid phases in a dynamic state using the dual energy gamma ray tomography. The key results of the holdup distribution studies in the slurry bubble column along with the validation of the dual source gamma ray tomography system would be presented and discussed

  14. Analysis of a Hybrid PV/Thermal Solar-Assisted Heat Pump System for Sports Center Water Heating Application

    Directory of Open Access Journals (Sweden)

    Y. Bai

    2012-01-01

    Full Text Available The application of solar energy provides an alternative way to replace the primary source of energy, especially for large-scale installations. Heat pump technology is also an effective means to reduce the consumption of fossil fuels. This paper presents a practical case study of combined hybrid PV/T solar assisted heat pump (SAHP system for sports center hot water production. The initial design procedure was first presented. The entire system was then modeled with the TRNSYS 16 computation environment and the energy performance was evaluated based on year round simulation results. The results show that the system COP can reach 4.1 under the subtropical climate of Hong Kong, and as compared to the conventional heating system, a high fractional factor of energy saving at 67% can be obtained. The energy performances of the same system under different climatic conditions, that include three other cities in France, were analyzed and compared. Economic implications were also considered in this study.

  15. Temporal resolution and motion artifacts in single-source and dual-source cardiac CT

    International Nuclear Information System (INIS)

    Schöndube, Harald; Allmendinger, Thomas; Stierstorfer, Karl; Bruder, Herbert; Flohr, Thomas

    2013-01-01

    Purpose: The temporal resolution of a given image in cardiac computed tomography (CT) has so far mostly been determined from the amount of CT data employed for the reconstruction of that image. The purpose of this paper is to examine the applicability of such measures to the newly introduced modality of dual-source CT as well as to methods aiming to provide improved temporal resolution by means of an advanced image reconstruction algorithm. Methods: To provide a solid base for the examinations described in this paper, an extensive review of temporal resolution in conventional single-source CT is given first. Two different measures for assessing temporal resolution with respect to the amount of data involved are introduced, namely, either taking the full width at half maximum of the respective data weighting function (FWHM-TR) or the total width of the weighting function (total TR) as a base of the assessment. Image reconstruction using both a direct fan-beam filtered backprojection with Parker weighting as well as using a parallel-beam rebinning step are considered. The theory of assessing temporal resolution by means of the data involved is then extended to dual-source CT. Finally, three different advanced iterative reconstruction methods that all use the same input data are compared with respect to the resulting motion artifact level. For brevity and simplicity, the examinations are limited to two-dimensional data acquisition and reconstruction. However, all results and conclusions presented in this paper are also directly applicable to both circular and helical cone-beam CT. Results: While the concept of total TR can directly be applied to dual-source CT, the definition of the FWHM of a weighting function needs to be slightly extended to be applicable to this modality. The three different advanced iterative reconstruction methods examined in this paper result in significantly different images with respect to their motion artifact level, despite exactly the same

  16. Temporal resolution and motion artifacts in single-source and dual-source cardiac CT.

    Science.gov (United States)

    Schöndube, Harald; Allmendinger, Thomas; Stierstorfer, Karl; Bruder, Herbert; Flohr, Thomas

    2013-03-01

    The temporal resolution of a given image in cardiac computed tomography (CT) has so far mostly been determined from the amount of CT data employed for the reconstruction of that image. The purpose of this paper is to examine the applicability of such measures to the newly introduced modality of dual-source CT as well as to methods aiming to provide improved temporal resolution by means of an advanced image reconstruction algorithm. To provide a solid base for the examinations described in this paper, an extensive review of temporal resolution in conventional single-source CT is given first. Two different measures for assessing temporal resolution with respect to the amount of data involved are introduced, namely, either taking the full width at half maximum of the respective data weighting function (FWHM-TR) or the total width of the weighting function (total TR) as a base of the assessment. Image reconstruction using both a direct fan-beam filtered backprojection with Parker weighting as well as using a parallel-beam rebinning step are considered. The theory of assessing temporal resolution by means of the data involved is then extended to dual-source CT. Finally, three different advanced iterative reconstruction methods that all use the same input data are compared with respect to the resulting motion artifact level. For brevity and simplicity, the examinations are limited to two-dimensional data acquisition and reconstruction. However, all results and conclusions presented in this paper are also directly applicable to both circular and helical cone-beam CT. While the concept of total TR can directly be applied to dual-source CT, the definition of the FWHM of a weighting function needs to be slightly extended to be applicable to this modality. The three different advanced iterative reconstruction methods examined in this paper result in significantly different images with respect to their motion artifact level, despite exactly the same amount of data being used

  17. Concentrating PV/T Hybrid System for Simultaneous Electricity and Usable Heat Generation: A Review

    Directory of Open Access Journals (Sweden)

    Longzhou Zhang

    2012-01-01

    Full Text Available Photovoltaic (PV power generation is one of the attractive choices for efficient utilization of solar energy. Considering that the efficiency and cost of PV cells cannot be significantly improved in near future, a relatively cheap concentrator to replace part of the expensive solar cells could be used. The photovoltaic thermal hybrid system (PV/T, combining active cooling with thermal electricity and providing both electricity and usable heat, can enhance the total efficiency of the system with reduced cell area. The effect of nonuniform light distribution and the heat dissipation on the performance of concentrating PV/T was discussed. Total utilization of solar light by spectral beam splitting technology was also introduced. In the last part, we proposed an integrated compound parabolic collector (CPC plate with low precision solar tracking, ensuring effective collection of solar light with a significantly lowered cost. With the combination of beam splitting of solar spectrum, use of film solar cell, and active liquid cooling, efficient and full spectrum conversion of solar light to electricity and heat, in a low cost way, might be realized. The paper may offer a general guide to those who are interested in the development of low cost concentrating PV/T hybrid system.

  18. Design of wearable hybrid generator for harvesting heat energy from human body depending on physiological activity

    Science.gov (United States)

    Kim, Myoung-Soo; Kim, Min-Ki; Kim, Kyongtae; Kim, Yong-Jun

    2017-09-01

    We developed a prototype of a wearable hybrid generator (WHG) that is used for harvesting the heat energy of the human body. This WHG is constructed by integrating a thermoelectric generator (TEG) in a circular mesh polyester knit fabric, circular-shaped pyroelectric generator (PEG), and quick sweat-pickup/dry-fabric. The fabric packaging enables the TEG part of the WHG to generate energy steadily while maintaining a temperature difference in extreme temperature environments. Moreover, when the body sweats, the evaporation heat of the sweat leads to thermal fluctuations in the WHG. This phenomenon further leads to an increase in the output power of the WHG. These characteristics of the WHG make it possible to produce electrical energy steadily without reduction in the conversion efficiency, as both TEG and PEG use the same energy source of the human skin and the ambient temperature. Under a temperature difference of ˜6.5 °C and temperature change rate of ˜0.62 °C s-1, the output power and output power density of the WHG, respectively, are ˜4.5 nW and ˜1.5 μW m-2. Our hybrid approach will provide a framework to enhance the output power of the wearable generators that harvest heat energy from human body in various environments.

  19. Design and simulation of a hybrid ventilation system with earth-air heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Athienitis, A.K.; Zhao, M. [Concordia Univ., Centre for Building Studies, Montreal, PQ (Canada). Dept. of Building, Civil and Environmental Engineering; Roy, M. [Martin Roy and Associes Group Conseil Inc., Montreal, PQ (Canada)

    2005-07-01

    A simulation study was conducted during the design phase of a new circus building in Montreal which includes a hybrid ventilation system through which fresh air is supplied from an earth-air heat exchanger (EAHE). The EAHE has the potential to satisfy the cooling needs of the building and can also be used to preheat fresh air, thereby satisfying one-third or more of the building's heating needs. Another feature of the building is that it uses displacement ventilation by which the air is supplied at low velocities through large diffusers behind the top level seats or under the seats. In this study, computational fluid dynamics (CFD) simulations were carried out to help size the supply and return units of the heating, ventilating and air conditioning (HVAC) system, as well as the exhaust chimney. The primary objective of the CFD simulation was to determine the maximum velocity and temperature in the seated area to ensure thermal comfort. CFD simulation predictions were found to be in good agreement with preliminary measurements taken in the building. In order to monitor the operation of the system over the next year, the underground ducts were equipped with temperature sensors at several depths into the soil. The energy efficiency of the hybrid HVAC system will be assessed and the velocity and temperature distribution in the theatre will be examined under various operating and energy load conditions. 8 refs., 6 figs.

  20. Averthermodynamic analysis of waste heat recovery for cooling systems in hybrid and electric vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Javani, N.; Dincer, I.; Naterer, G.F. [Faculty of Engineering and Applied Science, University of Ontario Institute of Technology (Canada)], email: nader.javani@uoit.ca

    2011-07-01

    The transportation sector is a heavy consumer of energy and better energy use is needed to reduce fuel consumption. One way to improve energy usage is to recover waste heat for cabin heating, cooling, or to produce electricity. The aim of this paper is to examine the use of waste heat in hybrid electric vehicles (HEV) and electric vehicles for cooling purposes using an ejector cooling cycle and an absorption cooling cycle. Energy and exergy analyses were conducted using waste heat from the battery pack and the exhaust gases to power the boiler and generator. Results showed that waste energy from the battery pack does not provide enough energy to produce cabin cooling but that exhaust gases can produce 7.32 kW and 7.91 kW cooling loads in the ejector and absorption systems. This study demonstrated that both ejector and absorption systems can reduce energy consumption in vehicles through the use of waste heat from exhaust gases.

  1. Hybrid compression/absorption type heat utilization system (eco-energy city project)

    Energy Technology Data Exchange (ETDEWEB)

    Karimata, T.; Susami, S.; Ogawa, Y. [Research and Development Dept., EBARA Corp., Kanagawa pref. (Japan)

    1999-07-01

    This research is intended to develop a 'hybrid compression/absorption type heat utilization system' by combining an absorption process with a compression process in one circulation cycle. This system can produce chilling heat for ice thermal storage by utilizing low-temperature waste heat (lower than 100 C) which is impossible to treat with a conventional absorption chiller. It means that this system will be able to solve the problem of a timing mismatch between waste heat and heat demand. The working fluid used in this proposed system should be suitable for producing ice, be safe, and not damage the ozone layer. In this project, new working fluids were searched as substitutes for the existing H{sub 2}O/LiBr or NH{sub 3}/H{sub 2}O. The interim results of this project in 1997, a testing unit using NH{sub 3}/H{sub 2}O was built for demonstration of the system and evaluation of its characteristics, and R134a/E181 was found to be one of the good working fluid for this system. The COP (ratio of energy of ice produced to electric power provided) of this system using R134a/E181 is expected to achieve 5.5 by computer simulation. The testing unit with this working fluid was built recently and prepared for the tests to confirm the result of the simulation. (orig.)

  2. Investigation of impurity confinement in lower hybrid wave heated plasma on EAST tokamak

    Science.gov (United States)

    Xu, Z.; Wu, Z. W.; Zhang, L.; Gao, W.; Ye, Y.; Chen, K. Y.; Yuan, Y.; Zhang, W.; Yang, X. D.; Chen, Y. J.; Zhang, P. F.; Huang, J.; Wu, C. R.; Morita, S.; Oishi, T.; Zhang, J. Z.; Duan, Y. M.; Zang, Q.; Ding, S. Y.; Liu, H. Q.; Chen, J. L.; Hu, L. Q.; Xu, G. S.; Guo, H. Y.; the EAST Team

    2018-01-01

    The transient perturbation method with metallic impurities such as iron (Fe, Z  =  26) and copper (Cu, Z  =  29) induced in plasma-material interaction (PMI) procedure is used to investigate the impurity confinement characters in lower hybrid wave (LHW) heated EAST sawtooth-free plasma. The dependence of metallic impurities confinement time on plasma parameters (e.g. plasma current, toroidal magnetic field, electron density and heating power) are investigated in ohmic and LHW heated plasma. It is shown that LHW heating plays an important role in the reduction of the impurity confinement time in L-mode discharges on EAST. The impurity confinement time scaling is given as 42IP0.32Bt0.2\\overline{n}e0.43Ptotal-0.4~ on EAST, which is close to the observed scaling on Tore Supra and JET. Furthermore, the LHW heated high-enhanced-recycling (HER) H-mode discharges with ~25 kHz edge coherent modes (ECM), which have lower impurity confinement time and higher energy confinement time, provide promising candidates for high performance and steady state operation on EAST.

  3. High-pitch dual-source CT coronary angiography with low volumes of contrast medium

    International Nuclear Information System (INIS)

    Lembcke, Alexander; Hein, Patrick A.; Knobloch, Gesine; Durmus, Tahir; Hamm, Bernd; Schwenke, Carsten; Huppertz, Alexander

    2014-01-01

    To assess the effect of lower volumes of contrast medium (CM) on image quality in high-pitch dual-source computed tomography coronary angiography (CTCA). One-hundred consecutive patients (body weight 65-85 kg, stable heart rate ≤65 bpm, cardiac index ≥2.5 L/min/m 2 ) referred for CTCA were prospectively enrolled. Patients were randomly assigned to one of five groups of different CM volumes (G 30 , 30 mL; G 40 , 40 mL; G 50 , 50 mL; G 60 , 60 mL; G 70 , 70 mL; flow rate 5 mL/s each, iodine content 370 mg/mL). Attenuation within the proximal and distal coronary artery segments was analysed. Mean attenuation for men and women ranged from 345.0 and 399.1 HU in G 30 to 478.2 and 571.8 HU in G 70 . Mean attenuation values were higher in groups with higher CM volumes (P 30 , G 40 , G 50 , G 60 and G 70 were 89 %, 95 %, 98 %, 98 % and 99 %. CM volume of 30 mL in women and 40 mL in men proved to be sufficient to guarantee attenuation of at least 300 HU. In selected patients high-pitch dual-source CTCA can be performed with CM volumes of 40 mL in men or 30 mL in women. (orig.)

  4. Study of parametric instabilities during the Alcator C lower hybrid wave heating experiments

    International Nuclear Information System (INIS)

    Takase, Y.

    1983-10-01

    Parametric excitation of ion-cyclotron quasi-modes (ω/sub R/ approx. = nω/sub ci/) and ion-sound quasi-modes (ω/sub R/ approx. = k/sub parallel to/v/sub ti/) during lower hybrid wave heating of tokamak plasmas have been studied in detail. Such instabilities may significantly modify the incident wavenumber spectrum near the plasma edge. Convective losses for these instabilities are high if well-defined resonance cones exist, but they are significantly reduced if the resonance cones spread and fill the plasma volume (or some region of it). These instabilities preferentially excite lower hybrid waves with larger values of n/sub parallel to/ than themselves possess, and the new waves tend to be absorbed near the outer layers of the plasma. Parametric instabilities during lower hybrid heating of Alcator C plasmas have been investigated using rf probes (to study tilde phi and tilde n/sub i/) and CO 2 scattering technique (to study tilde n/sub e/). At lower densities (anti n/sub e/ less than or equal to 0.5 x 10 14 cm -3 ) where waves observed in the plasma interior using CO 2 scattering appear to be localized, parametric decay is very weak. Both ion-sound and ion-cyclotron parametric decay processes have been observed at higher densities (anti n greater than or equal to 1.5 x 10 14 cm -3 ) where waves appear to be unlocalized. Finally, at still higher densities (anti n /sub e/ greater than or equal to 2 x 10 4 cm -3 ) pump depletion has been observed. Above these densities heating and current drive efficiencies are expected to degrade significantly

  5. Performance Evaluation of the Concept of Hybrid Heat Pipe as Passive In-core Cooling Systems for Advanced Nuclear Power Plant

    International Nuclear Information System (INIS)

    Jeong, Yeong Shin; Kim, Kyung Mo; Kim, In Guk; Bang, In Cheol

    2015-01-01

    As an arising issue for inherent safety of nuclear power plant, the concept of hybrid heat pipe as passive in-core cooling systems was introduced. Hybrid heat pipe has unique features that it is inserted in core directly to remove decay heat from nuclear fuel without any changes of structures of existing facilities of nuclear power plant, substituting conventional control rod. Hybrid heat pipe consists of metal cladding, working fluid, wick structure, and neutron absorber. Same with working principle of the heat pipe, heat is transported by phase change of working fluid inside metal cask. Figure 1 shows the systematic design of the hybrid heat pipe cooling system. In this study, the concept of a hybrid heat pipe was introduced as a Passive IN-core Cooling Systems (PINCs) and demonstrated for internal design features of heat pipe containing neutron absorber. Using a commercial CFD code, single hybrid heat pipe model was analyzed to evaluate thermal performance in designated operating condition. Also, 1-dimensional reactor transient analysis was done by calculating temperature change of the coolant inside reactor pressure vessel using MATLAB. As a passive decay heat removal device, hybrid heat pipe was suggested with a concept of combination of heat pipe and control rod. Hybrid heat pipe has distinct feature that it can be a unique solution to cool the reactor when depressurization process is impossible so that refueling water cannot be injected into RPV by conventional ECCS. It contains neutron absorber material inside heat pipe, so it can stop the reactor and at the same time, remove decay heat in core. For evaluating the concept of hybrid heat pipe, its thermal performance was analyzed using CFD and one-dimensional transient analysis. From single hybrid heat pipe simulation, the hybrid heat pipe can transport heat from the core inside to outside about 18.20 kW, and total thermal resistance of hybrid heat pipe is 0.015 .deg. C/W. Due to unique features of long heat

  6. Lower hybrid heating and current drive in ignitor shear reversal scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Barbato, E; Pinaccione, L [Italian Agengy for New Technologies, Energy and the Environment, Centro Ricerche Frascati, Rome (Italy). Dip. Energia

    1996-05-01

    Injection of Lower Hybrid (LH) Wave power at 8 GHz is considered into IGNITOR shear reversal scenarios, characterized by a reduced plasma current and density. Power deposition calculation are performed to establish whether LH waves can be used both as central heating and off axis current drive tool. It turns out that LH waves can be used (a) for central plasma heating purpose during the current vamp phase, to freeze the shear reversed configuration, at the power level of {approx}10 MW. (b) to drive a current in the outer part of the plasma at the power level of 20 MW. In this way around 1/3-1/6 of the total current in the proper plasma position (i.e. where q is minimum) is driven.

  7. A hybrid system using a regenerative electrochemical cycle to harvest waste heat from the proton exchange membrane fuel cell

    International Nuclear Information System (INIS)

    Long, Rui; Li, Baode; Liu, Zhichun; Liu, Wei

    2015-01-01

    A new hybrid system consisting of a PEMFC (proton exchange membrane fuel cell) subsystem and a TREC (thermally regenerative electrochemical cycle) subsystem is proposed to convert the waste heat produced by the PEMFC system into electricity. The performance of the hybrid system and its corresponding subsystems is analyzed. Results reveal that there exists optimal current densities of the PEMFC and TREC systems leading to the maximum power output of the hybrid system. With the maximum power output as the objective function, an optimization of the hybrid system based on genetic algorithm method is conducted under different operating temperatures of the PEMFC subsystem. The power output of the hybrid system is 6.85%–20.59% larger than that of the PEMFC subsystem. And the total electrical efficiency is improved by 2.74%–8.27%. The corresponding electrical efficiency of the TREC is 4.56%–13.81%. The hybrid system proposed in this paper could contribute to utilizing the fuel energy more efficiently and sufficiently. - Highlights: • A hybrid power system consisting of a PEMFC and a TREC subsystems is proposed. • Parameters' impacts on performance of the hybrid system have been analyzed. • The maximum power output of the hybrid system is investigated based on genetic algorithm. • Total power output of the hybrid system is 7.63%–18.84% larger than that of the PEMFC subsystem.

  8. Hybrid mesh finite volume CFD code for studying heat transfer in a forward-facing step

    Energy Technology Data Exchange (ETDEWEB)

    Jayakumar, J S; Kumar, Inder [Bhabha Atomic Research Center, Mumbai (India); Eswaran, V, E-mail: jsjayan@gmail.com, E-mail: inderk@barc.gov.in, E-mail: eswar@iitk.ac.in [Indian Institute of Technology, Kanpur (India)

    2010-12-15

    Computational fluid dynamics (CFD) methods employ two types of grid: structured and unstructured. Developing the solver and data structures for a finite-volume solver is easier than for unstructured grids. But real-life problems are too complicated to be fitted flexibly by structured grids. Therefore, unstructured grids are widely used for solving real-life problems. However, using only one type of unstructured element consumes a lot of computational time because the number of elements cannot be controlled. Hence, a hybrid grid that contains mixed elements, such as the use of hexahedral elements along with tetrahedral and pyramidal elements, gives the user control over the number of elements in the domain, and thus only the domain that requires a finer grid is meshed finer and not the entire domain. This work aims to develop such a finite-volume hybrid grid solver capable of handling turbulence flows and conjugate heat transfer. It has been extended to solving flow involving separation and subsequent reattachment occurring due to sudden expansion or contraction. A significant effect of mixing high- and low-enthalpy fluid occurs in the reattached regions of these devices. This makes the study of the backward-facing and forward-facing step with heat transfer an important field of research. The problem of the forward-facing step with conjugate heat transfer was taken up and solved for turbulence flow using a two-equation model of k-{omega}. The variation in the flow profile and heat transfer behavior has been studied with the variation in Re and solid to fluid thermal conductivity ratios. The results for the variation in local Nusselt number, interface temperature and skin friction factor are presented.

  9. Hybrid mesh finite volume CFD code for studying heat transfer in a forward-facing step

    Science.gov (United States)

    Jayakumar, J. S.; Kumar, Inder; Eswaran, V.

    2010-12-01

    Computational fluid dynamics (CFD) methods employ two types of grid: structured and unstructured. Developing the solver and data structures for a finite-volume solver is easier than for unstructured grids. But real-life problems are too complicated to be fitted flexibly by structured grids. Therefore, unstructured grids are widely used for solving real-life problems. However, using only one type of unstructured element consumes a lot of computational time because the number of elements cannot be controlled. Hence, a hybrid grid that contains mixed elements, such as the use of hexahedral elements along with tetrahedral and pyramidal elements, gives the user control over the number of elements in the domain, and thus only the domain that requires a finer grid is meshed finer and not the entire domain. This work aims to develop such a finite-volume hybrid grid solver capable of handling turbulence flows and conjugate heat transfer. It has been extended to solving flow involving separation and subsequent reattachment occurring due to sudden expansion or contraction. A significant effect of mixing high- and low-enthalpy fluid occurs in the reattached regions of these devices. This makes the study of the backward-facing and forward-facing step with heat transfer an important field of research. The problem of the forward-facing step with conjugate heat transfer was taken up and solved for turbulence flow using a two-equation model of k-ω. The variation in the flow profile and heat transfer behavior has been studied with the variation in Re and solid to fluid thermal conductivity ratios. The results for the variation in local Nusselt number, interface temperature and skin friction factor are presented.

  10. Hybrid mesh finite volume CFD code for studying heat transfer in a forward-facing step

    International Nuclear Information System (INIS)

    Jayakumar, J S; Kumar, Inder; Eswaran, V

    2010-01-01

    Computational fluid dynamics (CFD) methods employ two types of grid: structured and unstructured. Developing the solver and data structures for a finite-volume solver is easier than for unstructured grids. But real-life problems are too complicated to be fitted flexibly by structured grids. Therefore, unstructured grids are widely used for solving real-life problems. However, using only one type of unstructured element consumes a lot of computational time because the number of elements cannot be controlled. Hence, a hybrid grid that contains mixed elements, such as the use of hexahedral elements along with tetrahedral and pyramidal elements, gives the user control over the number of elements in the domain, and thus only the domain that requires a finer grid is meshed finer and not the entire domain. This work aims to develop such a finite-volume hybrid grid solver capable of handling turbulence flows and conjugate heat transfer. It has been extended to solving flow involving separation and subsequent reattachment occurring due to sudden expansion or contraction. A significant effect of mixing high- and low-enthalpy fluid occurs in the reattached regions of these devices. This makes the study of the backward-facing and forward-facing step with heat transfer an important field of research. The problem of the forward-facing step with conjugate heat transfer was taken up and solved for turbulence flow using a two-equation model of k-ω. The variation in the flow profile and heat transfer behavior has been studied with the variation in Re and solid to fluid thermal conductivity ratios. The results for the variation in local Nusselt number, interface temperature and skin friction factor are presented.

  11. Thermo-economic optimization of a hybrid solar district heating plant with flat plate collectors and parabolic trough collectors in series

    DEFF Research Database (Denmark)

    Tian, Zhiyong; Perers, Bengt; Furbo, Simon

    2018-01-01

    heating network in this study. The results also show that parabolic trough collectors are economically feasible for district heating networks in Denmark. The generic and multivariable levelized cost of heat method can guide engineers and designers on the design, construction and control of large...... to optimize the hybrid solar district heating systems based on levelized cost of heat. It is found that the lowest net levelized cost of heat of hybrid solar heating plants could reach about 0.36 DKK/kWh. The system levelized cost of heat can be reduced by 5–9% by use of solar collectors in the district...

  12. Cadmium Sulfide Nanoparticles Synthesized by Microwave Heating for Hybrid Solar Cell Applications

    Directory of Open Access Journals (Sweden)

    Claudia Martínez-Alonso

    2014-01-01

    Full Text Available Cadmium sulfide nanoparticles (CdS-n are excellent electron acceptor for hybrid solar cell applications. However, the particle size and properties of the CdS-n products depend largely on the synthesis methodologies. In this work, CdS-n were synthetized by microwave heating using thioacetamide (TA or thiourea (TU as sulfur sources. The obtained CdS-n(TA showed a random distribution of hexagonal particles and contained TA residues. The latter could originate the charge carrier recombination process and cause a low photovoltage (Voc, 0.3 V in the hybrid solar cells formed by the inorganic particles and poly(3-hexylthiophene (P3HT. Under similar synthesis conditions, in contrast, CdS-n synthesized with TU consisted of spherical particles with similar size and contained carbonyl groups at their surface. CdS-n(TU could be well dispersed in the nonpolar P3HT solution, leading to a Voc of about 0.6–0.8 V in the resulting CdS-n(TU : P3HT solar cells. The results of this work suggest that the reactant sources in microwave methods can affect the physicochemical properties of the obtained inorganic semiconductor nanoparticles, which finally influenced the photovoltaic performance of related hybrid solar cells.

  13. Potential Evaluation of Solar Heat Assisted Desiccant Hybrid Air Conditioning System

    Science.gov (United States)

    Tran, Thien Nha; Hamamoto, Yoshinori; Akisawa, Atsushi; Kashiwagi, Takao

    The solar thermal driven desiccant dehumidification-absorption cooling hybrid system has superior advantage in hot-humid climate regions. The reasonable air processing of desiccant hybrid air conditioning system and the utility of clean and free energy make the system environment friendly and energy efficient. The study investigates the performance of the desiccant dehumidification air conditioning systems with solar thermal assistant. The investigation is performed for three cases which are combinations of solar thermal and absorption cooling systems with different heat supply temperature levels. Two solar thermal systems are used in the study: the flat plate collector (FPC) and the vacuum tube with compound parabolic concentrator (CPC). The single-effect and high energy efficient double-, triple-effect LiBr-water absorption cooling cycles are considered for cooling systems. COP of desiccant hybrid air conditioning systems are determined. The evaluation of these systems is subsequently performed. The single effect absorption cooling cycle combined with the flat plate collector solar system is found to be the most energy efficient air conditioning system.

  14. A review of concentrated photovoltaic-thermal (CPVT) hybrid solar systems with waste heat recovery (WHR)

    Institute of Scientific and Technical Information of China (English)

    Xing Ju; Chao Xu; Zhirong Liao; Xiaoze Du; Gaosheng Wei; Zhifeng Wang; Yongping Yang

    2017-01-01

    In conventional photovoltaic (PV) systems,a large portion of solar energy is dissipated as waste heat since the generating efficiency is usually less than 30%.As the dissipated heat can be recovered for various applications,the wasted heat recovery concentrator PV/thermal (WHR CPVT) hybrid systems have been developed.They can provide both electricity and usable heat by combining thermal systems with concentrator PV (CPV) module,which dramatically improves the overall conversion efficiency of solar energy.This paper systematically and comprehensively reviews the research and development ofWHR CPVT systems.WHR CPVT systems with innovative design configurations,different theoretical evaluation models and experimental test processes for several implementations are presented in an integrated manner.We aim to provide a global point of view on the research trends,market potential,technical obstacles,and the future work which is required in the development of WHR CPVT technology.Possibly,it will offer a generic guide to the investigators who are interested in the study of WHR CPVT systems.

  15. Hybrid heating systems optimization of residential environment to have thermal comfort conditions by numerical simulation.

    Science.gov (United States)

    Jahantigh, Nabi; Keshavarz, Ali; Mirzaei, Masoud

    2015-01-01

    The aim of this study is to determine optimum hybrid heating systems parameters, such as temperature, surface area of a radiant heater and vent area to have thermal comfort conditions. DOE, Factorial design method is used to determine the optimum values for input parameters. A 3D model of a virtual standing thermal manikin with real dimensions is considered in this study. Continuity, momentum, energy, species equations for turbulent flow and physiological equation for thermal comfort are numerically solved to study heat, moisture and flow field. K - ɛRNG Model is used for turbulence modeling and DO method is used for radiation effects. Numerical results have a good agreement with the experimental data reported in the literature. The effect of various combinations of inlet parameters on thermal comfort is considered. According to Pareto graph, some of these combinations that have significant effect on the thermal comfort require no more energy can be used as useful tools. A better symmetrical velocity distribution around the manikin is also presented in the hybrid system.

  16. In vitro differentiation of renal stone composition using dual-source, dual-energy CT

    International Nuclear Information System (INIS)

    Zhou Changsheng; Zhang Longjiang; Xu Feng; Qi Li; Zhao Yan'e; Zheng Ling; Huang Wei; Liu Youhuang; Lu Guangming

    2012-01-01

    Objective: To evaluate the ability of dual-source. dual-energy CT in differentiating uric acid stones from non-uric acid stones with infrared spectroscopy as reference standard. Materials and Methods: Urinary calculus from 308 patients were scanned in first generation dual-source CT with dual-energy mode between July 2011 and June 2012. Renal Stone application was used to analyze their composition. The uric acid stones color were coded red and non-uric acid stones were blue. CT values were measured in 60 selective urinary calculus including 30 uric acid stones and 30 non-uric acid stones. The accuracy of dual energy CT to differentiate uric acid and no-uric acid stones was calculated. Results: Of 308 patients, 60 patients had uric acid stones and 248 non-uric acid stones. No difference was found for uric acid stone at 80 kV and 140 kV (375.8±69.2 HU vs. 374.1±69.4 HU; t=-0.217, P=0.830), while CT values of non-uric acid stones were higher at 80 kV than those at 140 kV (1455.1±312.4 HU vs. 1039.6±194.4 HU; t=-12.16. P<0.001). CT values of non-uric acid stones at 80 kV, 140 kV, and average weighted images (1455.1±312.4 HU, 1 039.6±194.4 HU, and 882.0±176.4 HU, respectively) were higher than those of uric acid stones (375.8±69.2 HU, 374.1±69.4 HU, and 366.3±80.1 HU, respectively; P<0.001). With infrared spectrum findings as reference standard, the accuracy of dual energy CT in differentiating uric acid stones from non-uric acid stones was 100%. Conclusions: Dual-source, dual-energy CT can accurately differentiate uric acid stones from non-uric acid stones, and plays an important role in treatment planning of renal stones. (authors)

  17. Numerical simulation of the induction heating of hybrid semi-finished materials into the semi-solid state

    Science.gov (United States)

    Seyboldt, Christoph; Liewald, Mathias

    2017-10-01

    Current research activities at the Institute for Metal Forming Technology (IFU) of the University of Stuttgart are focusing on the manufacturing of hybrid components using semi-solid forming strategies. As part of the research project "Hybrid interaction during and after thixoforging of multi-material systems", which is founded by the German Research Foundation (DFG), a thixoforging process for producing hybrid components with cohesive metal-to-metal connections is developed. In this context, this paper deals with the numerical simulation of the inductive heating process of hybrid semi-finished materials, consisting of two different aluminium alloys. By reason of the skin effect that leads to inhomogeneous temperature distributions during inductive heating processes, the aluminium alloy with the higher melting point is thereby assembled in the outer side and the alloy with the lower melting point is assembled in the core of the semi-finished material. In this way, the graded heat distribution can be adapted to the used materialś flow properties that are heavily heat dependent. Without this graded heat distribution a proper forming process in the semi-solid state will not be possible. For numerically modelling the inductive heating system of the institute, a coupling of the magnetostatic and the thermal solver was realized by using Ansys Workbench. While the electromagnetic field and its associated heat production rate were solved in a frequency domain, the temperature development was solved in the time based domain. The numerical analysis showed that because of the high thermal conductivity of the aluminium, which leads to a rapid temperature equalization in the semi-finished material, the heating process has to be fast and with a high frequency for produce most heat in the outer region of the material. Finally, the obtained numerical results were validated with experimental heating tests.

  18. Dual-Source Swept-Source Optical Coherence Tomography Reconstructed on Integrated Spectrum

    Directory of Open Access Journals (Sweden)

    Shoude Chang

    2012-01-01

    Full Text Available Dual-source swept-source optical coherence tomography (DS-SSOCT has two individual sources with different central wavelengths, linewidth, and bandwidths. Because of the difference between the two sources, the individually reconstructed tomograms from each source have different aspect ratio, which makes the comparison and integration difficult. We report a method to merge two sets of DS-SSOCT raw data in a common spectrum, on which both data have the same spectrum density and a correct separation. The reconstructed tomographic image can seamlessly integrate the two bands of OCT data together. The final image has higher axial resolution and richer spectroscopic information than any of the individually reconstructed tomography image.

  19. A stochastic inventory management model for a dual sourcing supply chain with disruptions

    Science.gov (United States)

    Iakovou, Eleftherios; Vlachos, Dimitrios; Xanthopoulos, Anastasios

    2010-03-01

    As companies continue to globalise their operations and outsource significant portion of their value chain activities, they often end up relying heavily on order replenishments from distant suppliers. The explosion in long-distance sourcing is exposing supply chains and shareholder value at ever increasing operational and disruption risks. It is well established, both in academia and in real-world business environments, that resource flexibility is an effective method for hedging against supply chain disruption risks. In this contextual framework, we propose a single period stochastic inventory decision-making model that could be employed for capturing the trade-off between inventory policies and disruption risks for an unreliable dual sourcing supply network for both the capacitated and uncapacitated cases. Through the developed model, we obtain some important managerial insights and evaluate the merit of contingency strategies in managing uncertain supply chains.

  20. Dose performance and image quality: Dual source CT versus single source CT in cardiac CT angiography

    International Nuclear Information System (INIS)

    Wang Min; Qi Hengtao; Wang Ximing; Wang Tao; Chen, Jiu-Hong; Liu Cheng

    2009-01-01

    Objective: To evaluate dose performance and image quality of 64-slice dual source CT (DSCT) in comparison to 64-slice single source CT (SSCT) in cardiac CT angiography (CTA). Methods: 100 patients examined by DSCT and 60 patients scanned by SSCT were included in this study. Objective indices such as image noise, contrast-to-noise ratio and signal-to-noise ratio were analyzed. Subjective image quality was assessed by two cardiovascular radiologists in consensus using a four-point scale (1 = excellent to 4 = not acceptable). Estimation of effective dose was performed on the basis of dose length product (DLP). Results: At low heart rates ( 0.05), but, at high heart rates (>70 bpm), DSCT provided robust image quality (P 70 bpm), DSCT is able to provide robust diagnostic image quality at doses far below that of SSCT.

  1. High-pitch dual-source CT coronary angiography with low volumes of contrast medium

    Energy Technology Data Exchange (ETDEWEB)

    Lembcke, Alexander; Hein, Patrick A.; Knobloch, Gesine; Durmus, Tahir; Hamm, Bernd [Charite - University Medicine Berlin, Department of Radiology, Berlin (Germany); Schwenke, Carsten [SCO:SSiS - Schwenke Consulting, Berlin (Germany); Huppertz, Alexander [Charite - University Medicine Berlin, Department of Radiology, Berlin (Germany); ISI - Imaging Science Institute Charite, Berlin (Germany)

    2014-01-15

    To assess the effect of lower volumes of contrast medium (CM) on image quality in high-pitch dual-source computed tomography coronary angiography (CTCA). One-hundred consecutive patients (body weight 65-85 kg, stable heart rate ≤65 bpm, cardiac index ≥2.5 L/min/m{sup 2}) referred for CTCA were prospectively enrolled. Patients were randomly assigned to one of five groups of different CM volumes (G{sub 30}, 30 mL; G{sub 40}, 40 mL; G{sub 50}, 50 mL; G{sub 60}, 60 mL; G{sub 70}, 70 mL; flow rate 5 mL/s each, iodine content 370 mg/mL). Attenuation within the proximal and distal coronary artery segments was analysed. Mean attenuation for men and women ranged from 345.0 and 399.1 HU in G{sub 30} to 478.2 and 571.8 HU in G{sub 70}. Mean attenuation values were higher in groups with higher CM volumes (P < 0.0001) and higher in women than in men (P < 0.0001). The proportions of segments with attenuation of at least 300 HU in G{sub 30}, G{sub 40}, G{sub 50}, G{sub 60} and G{sub 70} were 89 %, 95 %, 98 %, 98 % and 99 %. CM volume of 30 mL in women and 40 mL in men proved to be sufficient to guarantee attenuation of at least 300 HU. In selected patients high-pitch dual-source CTCA can be performed with CM volumes of 40 mL in men or 30 mL in women. (orig.)

  2. Dual energy CTA of the supraaortic arteries: Technical improvements with a novel dual source CT system

    International Nuclear Information System (INIS)

    Lell, Michael M.; Hinkmann, Fabian; Nkenke, Emeka; Schmidt, Bernhard; Seidensticker, Peter; Kalender, Willi A.; Uder, Michael; Achenbach, Stephan

    2010-01-01

    Objectives: Computed tomography angiography (CTA) is a well-accepted imaging modality to evaluate the supraaortic vessels. Initial reports have suggested that dual energy CTA (DE-CTA) can enhance diagnosis by creating bone-free data sets, which can be visualized in 3D, but a number of limitations of this technique have also been addressed. We sought to describe the performance of DE-CTA of the supraaortic vessels with a novel dual source CT system with special emphasis on image quality and post-processing related artifacts. Materials and methods: Thirty-three patients underwent carotid CT angiography on a second generation dual source CT system. Simultaneous acquisitions of 100 and 140 kV data sets in arterial phase were performed. Two examiners evaluated overall bone suppression with a 3-point scale (1 = poor; 3 = excellent) and image quality regarding integrity of the vessel lumen of different vessel segments (n = 26) with a 5-point scale (1 = poor; 5 = excellent), CTA source data served as the reference. Results: Excellent bone suppression could be achieved in the head and neck. Only minor bone remnants occurred, mean score for bone removal was 2.9. Mean score for vessel integrity was 4.3. Eight hundred fifty-seven vessel segments could be evaluated. Six hundred thirty-five segments (74%) showed no lumen alteration, 65 segments (7.6%) lumen alterations 10% resulting in a total luminal reduction 50%, and 113 segments (13.2%) showed a gap in the vessel course (100% total lumen reduction). Artificial gaps of the vessel lumen occurred in 28 vessel segments due to artifacts caused by dental hardware and in all but one (65) ophthalmic arteries. Conclusions: Excellent bone suppression could be achieved, DE imaging with 100 and 140 kV lead to improved image quality and vessel integrity in the shoulder region than previously reported. The ophthalmic artery still cannot be adequately visualized.

  3. New normative standards of conditional reasoning and the dual-source model.

    Science.gov (United States)

    Singmann, Henrik; Klauer, Karl Christoph; Over, David

    2014-01-01

    There has been a major shift in research on human reasoning toward Bayesian and probabilistic approaches, which has been called a new paradigm. The new paradigm sees most everyday and scientific reasoning as taking place in a context of uncertainty, and inference is from uncertain beliefs and not from arbitrary assumptions. In this manuscript we present an empirical test of normative standards in the new paradigm using a novel probabilized conditional reasoning task. Our results indicated that for everyday conditional with at least a weak causal connection between antecedent and consequent only the conditional probability of the consequent given antecedent contributes unique variance to predicting the probability of conditional, but not the probability of the conjunction, nor the probability of the material conditional. Regarding normative accounts of reasoning, we found significant evidence that participants' responses were confidence preserving (i.e., p-valid in the sense of Adams, 1998) for MP inferences, but not for MT inferences. Additionally, only for MP inferences and to a lesser degree for DA inferences did the rate of responses inside the coherence intervals defined by mental probability logic (Pfeifer and Kleiter, 2005, 2010) exceed chance levels. In contrast to the normative accounts, the dual-source model (Klauer et al., 2010) is a descriptive model. It posits that participants integrate their background knowledge (i.e., the type of information primary to the normative approaches) and their subjective probability that a conclusion is seen as warranted based on its logical form. Model fits showed that the dual-source model, which employed participants' responses to a deductive task with abstract contents to estimate the form-based component, provided as good an account of the data as a model that solely used data from the probabilized conditional reasoning task.

  4. New Normative Standards of Conditional Reasoning and the Dual-Source Model

    Directory of Open Access Journals (Sweden)

    Henrik eSingmann

    2014-04-01

    Full Text Available There has been a major shift in research on human reasoning towards Bayesian and probabilistic approaches, which has been called a new paradigm. The new paradigm sees most everyday and scientific reasoning as taking place in a context of uncertainty, and inference is from uncertain beliefs and not from arbitrary assumptions. In this manuscript we present an empirical test of normative standards in the new paradigm using a novel probabilized conditional reasoning task. Our results indicated that for everyday conditional with at least a weak causal connection between antecedent and consequent only the conditional probability of the consequent given antecedent contributes unique variance to predicting the probability of conditional, but not the probability of the conjunction, nor the probability of the material conditional. Regarding normative accounts of reasoning, we found significant evidence that participants' responses were confidence preserving (i.e., p-valid in the sense of Adams, 1998 for MP inferences, but not for MT inferences. Additionally, only for MP inferences and to a lesser degree for DA inferences did the rate of responses inside the coherence intervals defined by mental probability logic (Pfeifer & Kleiter, 2005, 2010 exceed chance levels. In contrast to the normative accounts, the dual-source model (Klauer, Beller, & Hütter, 2010 is a descriptive model. It posits that participants integrate their background knowledge (i.e., the type of information primary to the normative approaches and their subjective probability that a conclusion is seen as warranted based on its logical form. Model fits showed that the dual-source model, which employed participants' responses to a deductive task with abstract contents to estimate the form-based component, provided as good an account of the data as a model that solely used data from the probabilized conditional reasoning task.

  5. Dual source and dual detector arrays tetrahedron beam computed tomography for image guided radiotherapy

    Science.gov (United States)

    Kim, Joshua; Lu, Weiguo; Zhang, Tiezhi

    2014-02-01

    Cone-beam computed tomography (CBCT) is an important online imaging modality for image guided radiotherapy. But suboptimal image quality and the lack of a real-time stereoscopic imaging function limit its implementation in advanced treatment techniques, such as online adaptive and 4D radiotherapy. Tetrahedron beam computed tomography (TBCT) is a novel online imaging modality designed to improve on the image quality provided by CBCT. TBCT geometry is flexible, and multiple detector and source arrays can be used for different applications. In this paper, we describe a novel dual source-dual detector TBCT system that is specially designed for LINAC radiation treatment machines. The imaging system is positioned in-line with the MV beam and is composed of two linear array x-ray sources mounted aside the electrical portal imaging device and two linear arrays of x-ray detectors mounted below the machine head. The detector and x-ray source arrays are orthogonal to each other, and each pair of source and detector arrays forms a tetrahedral volume. Four planer images can be obtained from different view angles at each gantry position at a frame rate as high as 20 frames per second. The overlapped regions provide a stereoscopic field of view of approximately 10-15 cm. With a half gantry rotation, a volumetric CT image can be reconstructed having a 45 cm field of view. Due to the scatter rejecting design of the TBCT geometry, the system can potentially produce high quality 2D and 3D images with less radiation exposure. The design of the dual source-dual detector system is described, and preliminary results of studies performed on numerical phantoms and simulated patient data are presented.

  6. Experimental investigation of a pulsating heat pipe for hybrid vehicle applications

    International Nuclear Information System (INIS)

    Burban, G.; Ayel, V.; Alexandre, A.; Lagonotte, P.; Bertin, Y.; Romestant, C.

    2013-01-01

    This paper deals with the experimental results of an unlooped pulsating heat pipe (PHP) developed and tested in an electronic thermal management field with hybrid vehicle applications in mind. The 2.5 mm inner tube diameter device was cooled by an air heat exchanger to replicate the environment of a vehicle. In order to characterize this pulsating heat pipe, four working fluids have been tested. They are acetone, methanol, water, and n-pentane, with applied thermal power ranging from 25 W to 550 W, air temperature ranging from 10 °C to 60 °C and air velocity ranging from 0.25 m s −1 to 2 m s −1 . Three inclinations have also been tested according to their horizontal positions: +45° (condenser above the evaporator), 0° and −45° (condenser below the evaporator). Among the different results, some of the most revelatory were obtained with regard to unfavourable inclination (−45°), for which the performances were very interesting considering a terrestrial application. On the other hand, one also observed low temperature limitations for water as a working fluid and degradation of performances for n-pentane tested at 60 °C air temperature. On an overall basis, however, it should be noted that the PHP functioned with high reliability and reproducibility and without any failure during the start-up or working stage. - Highlights: ► An unlooped pulsating heat pipe (PHP) has been tested varying heat power, air velocity and temperature, inclination and fluid. ► Four working fluids have been tested and classified into two groups according to the performances of the PHP. ► Interesting water phenomena have been highlighted in this study. ► The PHP worked with a good reliability and reproducibility.

  7. Experimental temperature analysis of simple & hybrid earth air tunnel heat exchanger in series connection at Bikaner Rajasthan India

    Science.gov (United States)

    Jakhar, O. P.; Sharma, Chandra Shekhar; Kukana, Rajendra

    2018-05-01

    The Earth Air Tunnel Heat Exchanger System is a passive air-conditioning system which has no side effect on earth climate and produces better cooling effect and heating effect comfortable to human body. It produces heating effect in winter and cooling effect in summer with the minimum power consumption of energy as compare to other air-conditioning devices. In this research paper Temperature Analysis was done on the two systems of Earth Air Tunnel Heat Exchanger experimentally for summer cooling purpose. Both the system was installed at Mechanical Engineering Department Government Engineering College Bikaner Rajasthan India. Experimental results concludes that the Average Air Temperature Difference was found as 11.00° C and 16.27° C for the Simple and Hybrid Earth Air Tunnel Heat Exchanger in Series Connection System respectively. The Maximum Air Temperature Difference was found as 18.10° C and 23.70° C for the Simple and Hybrid Earth Air Tunnel Heat Exchanger in Series Connection System respectively. The Minimum Air Temperature Difference was found as 5.20° C and 11.70° C for the Simple and Hybrid Earth Air Tunnel Heat Exchanger in Series Connection System respectively.

  8. Matching economical, energetic and environmental benefits: An analysis for hybrid CHCP-heat pump systems

    International Nuclear Information System (INIS)

    Cardona, Ennio; Piacentino, Antonio; Cardona, Fabio

    2006-01-01

    The optimization of design and operation of combined heat, cooling and power systems usually leads to select different plant lay-outs and size of components, depending on the adopted optimization criterion (maximum profit or energy saving or minimum environmental impact). This occurs when the current energy prices and the normative provisions supporting cogeneration are not able to coincide with the specific customer's interest and the overall 'social interest' for a reduction in energy consumption and in pollutants' emissions. At EU level, polygeneration is considered to have a large potential for residential and commercial buildings district network, for the tertiary sector and for industrial applications. In such applications, it is often convenient to integrate the trigeneration system with a reversible heat pump, because of a low ratio between electric demand and that for heating and cooling. In this paper, the design and operation of such hybrid systems is discussed. The results achievable through different operation modes are compared and, with reference to a 600-rooms hotel and a 300-beds hospital in Italy, the effects on plant design from an hour-by-hour optimization of plant operation are assessed. Finally, the need for a flexible support system for cogeneration plants is put into evidence and some criteria are listed for an effective regulation

  9. Demonstrating Hybrid Heat Transport and Energy Conversion System Performance Characterization Using Intelligent Control Systems

    International Nuclear Information System (INIS)

    Ostrum, Lee; Manic, Milos

    2017-01-01

    The debate continues on the magnitude and validity of climate change caused by human activities. However, there is no debate about the need to make buildings, modes of transportation, factories, and homes as energy efficient as possible. Given that climate change could occur with the wasteful use of fossil fuel and the fact that fossil energy costs could and will swing wildly, it is imperative that every effort be made to utilize energy sources to their fullest. Hybrid energy systems (HES) are two or more separate energy producers used together to produce energy commodities. The HES this report focuses on is the use of nuclear reactor waste heat as a source of further energy utilization. Nuclear reactors use a fluid to cool the core and produce the steam needed for the production of electricity. Traditionally this steam, or coolant, is used to convert the energy then cooled elsewhere. The heat is released into the environment without being used further. By adding technologies to nuclear reactors to use the wasted heat, a system can be developed to make more than just electricity and allow for loading following capabilities.

  10. Demonstrating Hybrid Heat Transport and Energy Conversion System Performance Characterization Using Intelligent Control Systems

    Energy Technology Data Exchange (ETDEWEB)

    Ostrum, Lee [Univ. of Idaho and Idaho Falls Center, Idaho Falls, ID (United States); Manic, Milos [Virginia Commonwealth Univ., Richmond, VA (United States)

    2017-09-28

    The debate continues on the magnitude and validity of climate change caused by human activities. However, there is no debate about the need to make buildings, modes of transportation, factories, and homes as energy efficient as possible. Given that climate change could occur with the wasteful use of fossil fuel and the fact that fossil energy costs could and will swing wildly, it is imperative that every effort be made to utilize energy sources to their fullest. Hybrid energy systems (HES) are two or more separate energy producers used together to produce energy commodities. The HES this report focuses on is the use of nuclear reactor waste heat as a source of further energy utilization. Nuclear reactors use a fluid to cool the core and produce the steam needed for the production of electricity. Traditionally this steam, or coolant, is used to convert the energy then cooled elsewhere. The heat is released into the environment without being used further. By adding technologies to nuclear reactors to use the wasted heat, a system can be developed to make more than just electricity and allow for loading following capabilities.

  11. 200 kW, 800 MHz transmitter system for lower hybrid heating

    International Nuclear Information System (INIS)

    Deitz, A.

    1975-01-01

    This paper describes a new rf heating system which has just been completed and is now operational on the ATC machine. The system utilizes four UHF TV klystrons to generate at least 200 kW of power at a frequency of 800 MHz. Pulse widths can be varied from 20 μsec up to 20 msec. A radar type floating deck modulator along with photo-optical transmitting and receiving devices have been incorporated into the system to provide the pulse fidelity and versatility which characterizes this equipment. Modular construction was emphasized in the design, when possible, to reduce maintenance and down time in the advent of component falilure. Hybrid combining techniques are utilized in order to provide two 100 kW feeds into the machine

  12. Hybrid RANS/LES of flow and heat transfer in round impinging jets

    International Nuclear Information System (INIS)

    Kubacki, Slawomir; Dick, Erik

    2011-01-01

    Fluid flow and convective heat transfer predictions are presented of round impinging jets for several combinations of nozzle-plate distances H/D = 2, 6 and 13.5 (where D is the nozzle diameter) and Reynolds numbers Re = 5000, 23,000 and 70,000 with the newest version of the k-ω model of and three hybrid RANS/LES models. In the RANS mode of the hybrid RANS/LES models, the k-ω model is recovered. Three formulations are considered to activate the LES mode. The first model is similar to the hybrid models of and . The turbulent length scale is replaced by the grid size in the destruction term of the k-equation and in the definition of the RANS eddy viscosity. As grid size, a maximum measure of the hexahedral grid cell is used. The second model has the same k-equation, but the eddy viscosity is the minimum of the k-ω eddy viscosity and the Smagorinsky eddy viscosity, following a proposal by . The Smagorinsky eddy viscosity is formed with the cube root of the cell volume. The third model has, again, the same k-equation, but has an eddy viscosity which is an intermediate between the eddy viscosities of the first and second models. This is reached by using the cube root of the cell volume in the eddy viscosity formula of the first model. The simulation results are compared with experimental data for the high Reynolds number cases Re = 23,000 and Re = 70,000 and LES data for the low-Reynolds number case Re = 5000. The Reynolds numbers are defined with the nozzle diameter and the bulk velocity at nozzle outlet. At low nozzle-plate distance (the impingement plate is in the core of the jet), turbulent kinetic energy is overpredicted by RANS in the stagnation flow region. This leads to overprediction of the heat transfer rate along the impingement plate in the impact zone. At high nozzle-plate distance (the impingement plate is in the mixed-out region of the jet), the turbulence mixing is underpredicted by RANS in the shear layer of the jet which gives a too high length of

  13. New 200 kW, 800 MHz transmitter system for lower hybrid heating

    International Nuclear Information System (INIS)

    Deitz, A.

    1975-07-01

    A new rf heating system which has just been completed and is being installed on the ATC machine is described. The system utilizes four uhf TV klystrons to generate at least 200 kW of power at a frequency of 800 MHz. Pulse widths can be varied from 20 μsec. up to 20 msec. A radar type floating deck modulator along with photo-optical transmitting and receiving devices have been incorporated into the system to provide the pulse fidelity and versatility which characterizes this equipment. Modular construction was emphasized in the design, when possible, to reduce maintenance and down time in the advent of component failure. Hybrid combining techniques are utilized in order to provide two 100 kW feeds into the machine. (U.S.)

  14. Heat and mass transfer analysis for paraffin/nitrous oxide burning rate in hybrid propulsion

    Science.gov (United States)

    Ben-Basat (Sisi), Shani; Gany, Alon

    2016-03-01

    This research presents a physical-mathematical model for the combustion of liquefying fuels in hybrid combustors, accounting for blowing effect on the heat transfer. A particular attention is given to a paraffin/nitrous oxide hybrid system. The use of a paraffin fuel in hybrid propulsion has been considered because of its much higher regression rate enabling significantly higher thrust compared to that of common polymeric fuels. The model predicts the overall regression rate (melting rate) of the fuel and the different mechanisms involved, including evaporation, entrainment of droplets of molten material, and mass loss due to melt flow on the condensed fuel surface. Prediction of the thickness and velocity of the liquid (melt) layer formed at the surface during combustion was done as well. Applying the model for an oxidizer mass flux of 45 kg/(s m2) as an example representing experimental range, it was found that 21% of the molten liquid undergoes evaporation, 30% enters the gas flow by the entrainment mechanism, and 49% reaches the end of the combustion chamber as a flowing liquid layer. When increasing the oxidizer mass flux in the port, the effect of entrainment increases while that of the flowing liquid layer along the surface shows a relatively lower contribution. Yet, the latter is predicted to have a significant contribution to the overall mass loss. In practical applications it may cause reduced combustion efficiency and should be taken into account in the motor design, e.g., by reinforcing the paraffin fuel with different additives. The model predictions have been compared to experimental results revealing good agreement.

  15. Energy Management of a Hybrid-Power Gas Engine-Driven Heat Pump

    Directory of Open Access Journals (Sweden)

    Qingkun Meng

    2015-10-01

    Full Text Available The hybrid-power gas engine-driven heat pump (HPGHP combines hybrid power technology with a gas engine heat pump. The engine in the power system is capable of operating constantly with high thermal efficiency and low emissions during different operating modes. In this paper, the mathematical models of various components is established, including the engine thermal efficiency map and the motor efficiency map. The comprehensive charging/discharging efficiency model and energy management optimization strategy model which is proposed to maximize the efficiency of instantaneous HPGHP system are established. Then, different charging/discharging torque limits are obtained. Finally, a novel gas engine economical zone control strategy which combined with the SOC of battery in real time is put forward. The main operating parameters of HPGHP system under energy management are simulated by Matlab/Simulink and validated by experimental data, such as engine and motor operating torque, fuel consumption rate and comprehensive efficiency, etc. The results show that during 3600 s’ run-time, the SOC value of battery packs varies between 0.58 and 0.705, the fuel consumption rate reaches minimum values of approximately 291.3 g/(kW h when the compressor speed is nearly 1550 rpm in mode D, the engine thermal efficiency and comprehensive efficiency reach maximum values of approximately 0.2727 and 0.2648 when the compressor speed is 1575 rpm and 1475 rpm, respectively, in mode D. In general, the motor efficiency can be maintained above 0.85 in either mode.

  16. [Clinical application of high-pitch excretory phase images during dual-source CT urography with stellar photon detector].

    Science.gov (United States)

    Sun, Hao; Xue, Hua-dan; Jin, Zheng-yu; Wang, Xuan; Chen, Yu; He, Yong-lan; Zhang, Da-ming; Zhu, Liang; Wang, Yun; Qi, Bing; Xu, Kai; Wang, Ming

    2014-10-01

    To retrospectively evaluate the clinical feasibility of high-pitch excretory phase images during dual-source CT urography with Stellar photon detector. Totally 100 patients received dual-source CT high-pitch urinary excretory phase scanning with Stellar photon detector [80 kV, ref.92 mAs, CARE Dose 4D and CARE kV, pitch of 3.0, filter back projection reconstruction algorithm (FBP)] (group A). Another 100 patients received dual-source CT high-pitch urinary excretory phase scanning with common detector(100 kV, ref.140 mAs, CARE Dose 4D, pitch of 3.0, FBP) (group B). Quantitative measurement of CT value of urinary segments (Hounsfield units), image noise (Hounsfield units), and effective radiation dose (millisievert) were compared using independent-samples t test between two groups. Urinary system subjective opacification scores were compared using Mann-Whitney U test between two groups. There was no significant difference in subjective opacification score of intrarenal collecting system and ureters between two groups (all P>0.05). The group A images yielded significantly higher CT values of all urinary segments (all P0.05). The effective radiation dose of group A (1.1 mSv) was significantly lower than that of group B (3.79 mSv) (Ppitch low-tube-voltage during excretory phase dual-source CT urography with Stellar photon detector is feasible, with acceptable image noise and lower radiation dose.

  17. Feasibility study of a hybrid renewable energy system with geothermal and solar heat sources for residential buildings in South Korea

    International Nuclear Information System (INIS)

    Kim, Young Ju; Woo, Nam Sub; Jang, Sung Cheol; Choi, Jeong Ju

    2013-01-01

    This study investigates the economic feasibility of a hybrid renewable energy system (HRES) that uses geothermal and solar heat sources for water heating, space heating, and space cooling in a residential building in Korea. A small-scale HRES consists of a geothermal heat pump for heating and cooling, solar collectors for hot water, a gas-fired backup boiler, and incidental facilities. To determine whether the Hares will produce any economic benefits for homeowners, an economic analysis is conducted to compare the Hares with conventional methods of space heating and cooling in Korea. The payback period of a small-scale Hares is predicted as a maximum of 9 yrs by life cycle costing based on a performance index compared with conventional systems. However, the payback period of large-scale HRES above 400 RT is 6 yrs to 7 yrs.

  18. Feasibility study of a hybrid renewable energy system with geothermal and solar heat sources for residential buildings in South Korea

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Ju; Woo, Nam Sub [Korea Institute of Geoscience and Mineral Resources, Daejeon (Korea, Republic of); Jang, Sung Cheol [Mechatronics Department of the Korea Aviation Polytechnic College, Sacheon (Korea, Republic of); Choi, Jeong Ju [Dong-A University, Busan (Korea, Republic of)

    2013-08-15

    This study investigates the economic feasibility of a hybrid renewable energy system (HRES) that uses geothermal and solar heat sources for water heating, space heating, and space cooling in a residential building in Korea. A small-scale HRES consists of a geothermal heat pump for heating and cooling, solar collectors for hot water, a gas-fired backup boiler, and incidental facilities. To determine whether the Hares will produce any economic benefits for homeowners, an economic analysis is conducted to compare the Hares with conventional methods of space heating and cooling in Korea. The payback period of a small-scale Hares is predicted as a maximum of 9 yrs by life cycle costing based on a performance index compared with conventional systems. However, the payback period of large-scale HRES above 400 RT is 6 yrs to 7 yrs.

  19. Expanding photovoltaic penetration with residential distributed generation from hybrid solar photovoltaic and combined heat and power systems

    International Nuclear Information System (INIS)

    Pearce, J.M.

    2009-01-01

    The recent development of small scale combined heat and power (CHP) systems has provided the opportunity for in-house power backup of residential-scale photovoltaic (PV) arrays. This paper investigates the potential of deploying a distributed network of PV + CHP hybrid systems in order to increase the PV penetration level in the U.S. The temporal distribution of solar flux, electrical and heating requirements for representative U.S. single family residences were analyzed and the results clearly show that hybridizing CHP with PV can enable additional PV deployment above what is possible with a conventional centralized electric generation system. The technical evolution of such PV + CHP hybrid systems was developed from the present (near market) technology through four generations, which enable high utilization rates of both PV-generated electricity and CHP-generated heat. A method to determine the maximum percent of PV-generated electricity on the grid without energy storage was derived and applied to an example area. The results show that a PV + CHP hybrid system not only has the potential to radically reduce energy waste in the status quo electrical and heating systems, but it also enables the share of solar PV to be expanded by about a factor of five. (author)

  20. A complete geothermal energy cycle with heat pumps and hybrid HVAC systems for the city of Denizli, Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Eltez, M. [Ege Univ., Izmir (Turkey). Mechanical Engineering Dept.; Kilkis, I.B. [Heatway Radiant Floors and Snowmelting, Springfield, MO (United States)]|[Middle East Technical Univ., Ankara (Turkey)

    1995-12-31

    This paper discusses general aspects of maximizing geofluid effectiveness by employing hybrid cycle plants coupled to district HVAC systems. Alternative and new techniques in space heating and cooling are also discussed. A case study is presented for the district HVAC system for the city of Denizli in Turkey. Results are compared with an open-cycle, open-loop system.

  1. Dual energy CTA of the supraaortic arteries: Technical improvements with a novel dual source CT system

    Energy Technology Data Exchange (ETDEWEB)

    Lell, Michael M., E-mail: Michael.lell@uk-erlangen.de [Department of Radiology, University Erlangen, Maximiliansplatz 1, 91054 Erlangen (Germany); Hinkmann, Fabian [Department of Radiology, University Erlangen, Maximiliansplatz 1, 91054 Erlangen (Germany); Nkenke, Emeka [Department of Maxillofacial Surgery, University Erlangen (Germany); Schmidt, Bernhard [Bayer-Schering Healthcare, Berlin (Germany); Seidensticker, Peter [Siemens Healthcare, CT-Division, Forchheim (Germany); Kalender, Willi A. [Institute of Medical Physics, University Erlangen (Germany); Uder, Michael [Department of Radiology, University Erlangen, Maximiliansplatz 1, 91054 Erlangen (Germany); Achenbach, Stephan [Department of Cardiology, University Erlangen (Germany)

    2010-11-15

    Objectives: Computed tomography angiography (CTA) is a well-accepted imaging modality to evaluate the supraaortic vessels. Initial reports have suggested that dual energy CTA (DE-CTA) can enhance diagnosis by creating bone-free data sets, which can be visualized in 3D, but a number of limitations of this technique have also been addressed. We sought to describe the performance of DE-CTA of the supraaortic vessels with a novel dual source CT system with special emphasis on image quality and post-processing related artifacts. Materials and methods: Thirty-three patients underwent carotid CT angiography on a second generation dual source CT system. Simultaneous acquisitions of 100 and 140 kV data sets in arterial phase were performed. Two examiners evaluated overall bone suppression with a 3-point scale (1 = poor; 3 = excellent) and image quality regarding integrity of the vessel lumen of different vessel segments (n = 26) with a 5-point scale (1 = poor; 5 = excellent), CTA source data served as the reference. Results: Excellent bone suppression could be achieved in the head and neck. Only minor bone remnants occurred, mean score for bone removal was 2.9. Mean score for vessel integrity was 4.3. Eight hundred fifty-seven vessel segments could be evaluated. Six hundred thirty-five segments (74%) showed no lumen alteration, 65 segments (7.6%) lumen alterations <10%, 27 segments (3.1%) lumen alterations >10% resulting in a total luminal reduction <50%, 17 segments (2%) lumen alterations of more than 10% resulting in a total luminal reduction >50%, and 113 segments (13.2%) showed a gap in the vessel course (100% total lumen reduction). Artificial gaps of the vessel lumen occurred in 28 vessel segments due to artifacts caused by dental hardware and in all but one (65) ophthalmic arteries. Conclusions: Excellent bone suppression could be achieved, DE imaging with 100 and 140 kV lead to improved image quality and vessel integrity in the shoulder region than previously

  2. Study of the heat transfers spectral radiation - conduction - natural convection in hybrid photovoltaic systems for buildings

    International Nuclear Information System (INIS)

    Muresan, C.

    2005-01-01

    The present work is supported by the CSTB and the ADEME and is a part of an Integrated Research Project - Energy Program of CNRS - (http://www.imp.cnrs.fr/energie/) coordinated by the CETHIL: 'Integration of hybrid Thermal - Photovoltaic solar collector in buildings'. In this context, this thesis represents upstream studies led in the I.R.P., pursuing the study itself of these hybrid components in stage of integration to the framework of buildings (thermal/electric management in response to the needs). Its objective falls under an action to identify and look further into knowledge of the limiting factors of the efficiency of these hybrid components (the operating temperature of the photosensitive cells), to identify the enduring scientific bolts persisting and to contribute to removing them. To reach this aim, predictive numerical tools are developed in order to guide and follow the future evolutions of these active wall elements. The problems related to the Photovoltaic components of Mono or Poly crystalline type, namely the risk of heating of the modules included within the built framework that can lead to a degradation of their energy efficiency. The developed model aims at obtaining the evaluation of the internal field of temperature. The modeling of the radiative behavior of multi-layer components of not scattering semi-transparent media is carried out. Propagation of a collimated flux corresponds to the direct solar radiation, and a diffuse flux represents the solar radiation diffused and that resulting from the other external sources (environment). Both are treated in a separate way. The incidental radiation power and radiative net flux are thus evaluated by a superposition of the values obtained at the time of the separate studies of the two components. The collimated component of incidental flux is treated according to an approach of 'ray tracing' type. The Discrete Ordinates Method (DOM) associated to the method of finite volumes, is employed for the

  3. Experimental studies on the hybrid system of heat and cold production from solar energy

    Directory of Open Access Journals (Sweden)

    Gil Stanislaw

    2017-01-01

    Full Text Available In recent years more and more energy is consumed in the European Union countries for summer air conditioning in buildings. This consumption will probably increase even more due to the predicted climate warming and the desire to improve the quality of life. At present final energy as heat and electricity is sourced mainly from fossil fuels. However, recently alternative renewable energy sources are increasingly taken into account as a result of efforts toward environmental protection and fuels savings. This paper presents results of the analysis of a hybrid solar-assisted heating and cooling system for buildings in the temperate climate of west and central Europe. Solar energy potential was estimated. The investigation was performed using a large scale laboratory installation, which contains an evacuated solar collector, a single-stage NH3-H2O absorption chiller and a hot water tank. The impact of the main system parameters on its performance was analyzed on the basis of energy balances.

  4. Controlled release of bupivacaine using hybrid thermoresponsive nanoparticles activated via photothermal heating.

    Science.gov (United States)

    Alejo, Teresa; Andreu, Vanesa; Mendoza, Gracia; Sebastian, Victor; Arruebo, Manuel

    2018-08-01

    Near-infrared (NIR) responsive nanoparticles are of great interest in the biomedical field as antennas for photothermal therapy and also as triggers for on-demand drug delivery. The present work reports the preparation of hollow gold nanoparticles (HGNPs) with plasmonic absorption in the NIR region covalently bound to a thermoresponsive polymeric shell that can be used as an on-demand drug delivery system for the release of analgesic drugs. The photothermal heating induced by the nanoparticles is able to produce the collapse of the polymeric shell thus generating the release of the local anesthetic bupivacaine in a spatiotemporally controlled way. Those HGNPs contain a 10 wt.% of polymer and present excellent reversible heating under NIR light excitation. Bupivacaine released at physiological temperature (37 °C) showed a pseudo-zero order release that could be spatiotemporally modified on-demand after applying several pulses of light/temperature above and below the lower critical solution temperature (LCST) of the polymeric shell. Furthermore, the nanomaterials obtained did not displayed detrimental effects on four mammalian cell lines at doses up to 0.2 mg/mL. From the results obtained it can be concluded than this type of hybrid thermoresponsive nanoparticle can be used as an externally activated on-demand drug delivery system. Copyright © 2018 Elsevier Inc. All rights reserved.

  5. Dual-source computed tomography in patients with acute chest pain: feasibility and image quality

    Energy Technology Data Exchange (ETDEWEB)

    Schertler, Thomas; Scheffel, Hans; Frauenfelder, Thomas; Desbiolles, Lotus; Leschka, Sebastian; Stolzmann, Paul; Marincek, Borut; Alkadhi, Hatem [University Hospital Zurich, Department of Medical Radiology, Institute of Diagnostic Radiology, Zurich (Switzerland); Seifert, Burkhardt [University of Zurich, Department of Biostatistics, Zurich (Switzerland); Flohr, Thomas G. [Computed Tomography CTE PA, Siemens Medical Solutions, Forchheim (Germany)

    2007-12-15

    The aim of this study was to determine the feasibility and image quality of dual-source computed tomography angiography (DSCTA) in patients with acute chest pain for the assessment of the lung, thoracic aorta, and for pulmonary and coronary arteries. Sixty consecutive patients (32 female, 28 male, mean age 58.1{+-}16.3 years) with acute chest pain underwent contrast-enhanced electrocardiography-gated DSCTA without prior beta-blocker administration. Vessel attenuation of different thoracic vascular territories was measured, and image quality was semi-quantitatively analyzed by two independent readers. Image quality of the thoracic aorta was diagnostic in all 60 patients, image quality of pulmonary arteries was diagnostic in 59, and image quality of coronary arteries was diagnostic in 58 patients. Pairwise intraindividual comparisons of attenuation values were small and ranged between 1{+-}6 HU comparing right and left coronary artery and 56{+-}9 HU comparing the pulmonary trunk and left ventricle. Mean attenuation was 291{+-}65 HU in the ascending aorta, 334{+-}93 HU in the pulmonary trunk, and 285{+-}66 HU and 268{+-}67 HU in the right and left coronary artery, respectively. DSCTA is feasible and provides diagnostic image quality of the thoracic aorta, pulmonary and coronary arteries in patients with acute chest pain. (orig.)

  6. Cerebral angiography with prospective ECG triggering preliminary study of dual-source CT

    International Nuclear Information System (INIS)

    Xue Yuejun; Qian Nong; Shao Yanhui; Pan Changjie; Rong Weiliang; Xu Yiqun

    2012-01-01

    Objective: To study the image quality and radiation dose in dual-source CT cerebral angiography with prospective ECG-triggered sequence mode (step-and-shoot, SAS). Methods: A total of forty-three patients with clinically suspected cerebral vascular disease underwent cerebral CT angiography with prospective ECG-triggering (step-and-shoot, SAS). Data acquisition was at 60% R-R interval of the ECG presentation mode. The post-processing included maximum intensity projection (MIP), multiplanar reformation (MPR) and volume rendering (VR). The CTA image quality, radiation dose and rates of excellent images were evaluated. Results: The CTA image quality score was 4.72 ± 0.50 and 97.7% (42/43) patients had excellent CTA images. The average effective dose of SAS-CTA was (0.22 ± 0.01)mSv, which was lower by 76.31% than that of DE-CTA. Conclusions: Prospective ECG-triggering sequence could be used in cerebral angiography with a significant reduction in radiation dose and diagnostic image quality. (authors)

  7. Automatic selection of optimal systolic and diastolic reconstruction windows for dual-source CT coronary angiography

    International Nuclear Information System (INIS)

    Seifarth, H.; Puesken, M.; Wienbeck, S.; Maintz, D.; Heindel, W.; Juergens, K.U.; Fischbach, R.

    2009-01-01

    The aim of this study was to assess the performance of a motion-map algorithm that automatically determines optimal reconstruction windows for dual-source coronary CT angiography. In datasets from 50 consecutive patients, optimal systolic and diastolic reconstruction windows were determined using the motion-map algorithm. For manual determination of the optimal reconstruction window, datasets were reconstructed in 5% steps throughout the RR interval. Motion artifacts were rated for each major coronary vessel using a five-point scale. Mean motion scores using the motion-map algorithm were 2.4 ± 0.8 for systolic reconstructions and 1.9 ± 0.8 for diastolic reconstructions. Using the manual approach, overall motion scores were significantly better (1.9 ± 0.5 and 1.7 ± 0.6, p 90% of cases using either approach. Using the automated approach, there was a negative correlation between heart rate and motion scores for systolic reconstructions (ρ = -0.26, p 80 bpm (systolic reconstruction). (orig.)

  8. Preliminary study of single contrast enhanced dual energy heart imaging using dual-source CT

    International Nuclear Information System (INIS)

    Peng Jin; Zhang Longjiang; Zhou Changsheng; Lu Guangming; Ma Yan; Gu Haifeng

    2009-01-01

    Objective: To evaluate the feasibility and preliminary applications of single contrast enhanced dual energy heart imaging using dual-source CT (DSCT). Methods: Thirty patients underwent dual energy heart imaging with DSCT, of which 6 cases underwent SPECT or DSA within one week. Two experienced radiologists assessed image quality of coronary arteries and iodine map of myocardium. and correlated the coronary artery stenosis with the perfusion distribution of iodine map. Results: l00% (300/300) segments reached diagnostic standards. The mean score of image for all patients was 4.68±0.57. Mural coronary artery was present in 10 segments in S cases, atherosclerotic plaques in 32 segments in 12 cases, of which 20 segments having ≥50% stenosis, 12 segments ≤50% stenosis; dual energy CT coronary angiography was consistent with the DSA in 3 patients. 37 segmental perfusion abnormalities on iodine map were found in 15 cases, including 28 coronary blood supply segment narrow segment and 9 no coronary stenosis (including three negative segments in SPECD. Conclusion: Single contrast enhanced dual energy heart imaging can provide good coronary artery and myocardium perfusion images in the patients with appropriate heart rate, which has a potential to be used in the clinic and further studies are needed. (authors)

  9. Dual-source computed tomography in patients with acute chest pain: feasibility and image quality

    International Nuclear Information System (INIS)

    Schertler, Thomas; Scheffel, Hans; Frauenfelder, Thomas; Desbiolles, Lotus; Leschka, Sebastian; Stolzmann, Paul; Marincek, Borut; Alkadhi, Hatem; Seifert, Burkhardt; Flohr, Thomas G.

    2007-01-01

    The aim of this study was to determine the feasibility and image quality of dual-source computed tomography angiography (DSCTA) in patients with acute chest pain for the assessment of the lung, thoracic aorta, and for pulmonary and coronary arteries. Sixty consecutive patients (32 female, 28 male, mean age 58.1±16.3 years) with acute chest pain underwent contrast-enhanced electrocardiography-gated DSCTA without prior beta-blocker administration. Vessel attenuation of different thoracic vascular territories was measured, and image quality was semi-quantitatively analyzed by two independent readers. Image quality of the thoracic aorta was diagnostic in all 60 patients, image quality of pulmonary arteries was diagnostic in 59, and image quality of coronary arteries was diagnostic in 58 patients. Pairwise intraindividual comparisons of attenuation values were small and ranged between 1±6 HU comparing right and left coronary artery and 56±9 HU comparing the pulmonary trunk and left ventricle. Mean attenuation was 291±65 HU in the ascending aorta, 334±93 HU in the pulmonary trunk, and 285±66 HU and 268±67 HU in the right and left coronary artery, respectively. DSCTA is feasible and provides diagnostic image quality of the thoracic aorta, pulmonary and coronary arteries in patients with acute chest pain. (orig.)

  10. Assessment of thoracic aortic elasticity: a preliminary study using electrocardiographically gated dual-source CT

    International Nuclear Information System (INIS)

    Li, Ning; Guo, Lijun; Sun, Haitao; Gao, Fei; Liu, Cheng; Beck, Thomas; Chen, Jiuhong; Biermann, Christina

    2011-01-01

    To gain a new insight into the elastic properties of the thoracic aorta in patients without aortic diseases using electrocardiographically (ECG)-gated dual-source (DS) CT. 56 subjects with no cardiovascular disease, selected from 2,700 people undergoing ECG-gated DSCT examination, were divided into three groups according to their age. CT data were reconstructed in 5% step throughout the RR interval. Diameter and area were measured at the curve of the ascending aorta (AA) and at the same level of the descending aorta (DA). The pulsation and elasticity of the aorta were evaluated. Aortic diameter changes were noted throughout the cardiac cycle. The maximum average diameter was seen at an RR interval of 24.02 ± 4.99% for the AA and 25.63 ± 4.77% for the DA. The minimum was at 93.5 ± 4.04% for the AA and 96.6 ± 4.58% for the DA. There was an age-dependent decrease in elasticity, while different correlation coefficients were found between various age groups and different elastic parameters. The properties of aortic pulsation and wall elasticity could be well shown by ECG-gated DSCT. The new findings regarding segment difference and age relevance were significant and should be taken into account in clinical trials and treatments for the elasticity related cardiovascular diseases. (orig.)

  11. Compressive strength measurements of hybrid dental composites treated with dry heat and light emitting diodes (LED post cure treatment

    Directory of Open Access Journals (Sweden)

    Jenny Krisnawaty

    2014-11-01

    Full Text Available Hybrid composites are mostly used on large cavities as restorative dental materials, whether it is used directly or indirectly. The mechanical properties of composite resin shall increase if it is treated with post cure treatment. The aim of this study is to evaluate compressive strength differences between dry heat and Light Emitting Diodes (LED treatment on the hybrid dental composite. A quasi-experimental was applied on this research with a total of 30 samples that were divided into two groups. Each sample was tested using LLOYD Universal Testing Machine with 1 mm/min speed to evaluate the compressive strength. The compressive strength results were marked when the sample was broken. The results of two groups were then analyzed using t-test statistical calculation. The results of this study show that post cure treatment on hybrid composite using LED light box (194.138 MPa was lower than dry heat treatment (227.339 MPa, which was also significantly different from statistical analysis. It can be concluded that compressive strength of LED light box was lower than dry heat post-cure treatment on the hybrid composite resin.

  12. Integrated power-heat-cold-coupling by switchable Stirling-Vuilleumier-Hybrid-Machines

    International Nuclear Information System (INIS)

    Kuehl, Hans-Detlev

    2017-01-01

    A Stirling engine consists in its so-called Gamma type on the one hand of a thermal compressor in which a double-acting displacer is the working gas between a ''hot'' and a ''warm'' (ie located on the heat use temperature level of the CHP application) cylinder chamber isochoric via a regenerator periodically shuffled back and forth. On the other hand, he has a spatially separated, one-sided working piston-cylinder system, which is connected to the ''warm'' side of the thermal compressor through an overflow and thus is at a similar temperature level. If an additional regenerator is inserted into this overflow channel, then the temperature levels are separated, since the heat output of the process takes place primarily via the warm cylinder space of the displacer system, while the cylinder space of the working piston constitutes a heat sink. This so-called ''hybrid'' process is still characterized by a - compared to the Stirling mode only slightly reduced - mechanical power output, but in addition by a theoretically equal to this magnitude, recorded on the cylinder at ''cold'' temperature cooling capacity, It thus represents an integrated system for power-heat-cold-coupling, which can be realized by a single thermodynamic process. Turning this process in the warm temperature range in addition to another, lying on the back of the working cylinder cylinder space, so that the former becomes a second, double-acting displacer, we finally get the known as a thermally driven heat pump or chiller Vuilleumier process that Ideally, no mechanical power gives or absorbs. At the Chair of Thermodynamics of the TU Dortmund, a research machine was developed and measured in a meanwhile completed research project funded by the DFG, which can switch between the three described processes and thus be adapted to changing power, heat and cooling requirements. In order to reduce the

  13. Dual-source dual-energy CT for the differentiation of urinary stone composition: preliminary study

    International Nuclear Information System (INIS)

    Yang Qifang; Zhang Wanshi; Meng Limin; Shi Huiping; Wang Dong; Bi Yongmin; Li Xiangsheng; Fang Hong; Guo Heqing; Yan Jingmin

    2011-01-01

    Objective: To evaluate dual-source dual-energy CT (DSCT) for the differentiation of' urinary stone composition in vitro. Methods: Ninety-seven urinary stones were obtained by endoscopic lithotripsy and scanned using dual-source dual-energy CT. The stones were divided into six groups according to infrared spectroscopy stone analysis: uric acid (UA) stones (n=10), cystine stones (n=5), struvite stones (n=6), calcium oxalate (CaOx) stones (n=22), mixed UA stones (n=7) and mixed calcium stones (n=47). Hounsfield units (HU) of each stone were recorded for the 80 kV and the 140 kV datasets by hand-drawing method. HU difference, HU ratio and dual energy index (DEI) were calculated and compared among the stone groups with one-way ANOVA. Using dual energy software to determine the composition of all stones, results were compared to infrared spectroscopy analysis. Results: There were statistical differences in HU difference [(-17±13), (229±34), (309±45), (512±97), (201±64) and (530±71) HU respectively], in HU ratio (0.96±0.03, 1.34±0.04, 1.41±0.03, 1.47±0.03, 1.30±0.07, and 1.49±0.03 respectively), and DEI (-0.006±0.004, 0.064±0.007, 0.080± 0.007, 0.108±0.011, 0.055±0.014 and 0.112±0.008 respectively) among different stone groups (F= 124.894, 407.028, 322.864 respectively, P<0.01). There were statistical differences in HU difference, HU ratio and DEI between UA stones and the other groups (P<0.01). There were statistical differences in HU difference, HU ratio and DEI between CaOx or mixed calcium stones and the other four groups (P< 0.01). There was statistical difference in HU ratio between cystine and struvite stones (P<0.01). There were statistical differences in HU difference, HU ratio and DEI between struvite and mixed UA stones (P< 0.05). Dual energy software correctly characterized 10 UA stones, 4 cystine stones, 22 CaOx stones and 6 mixed UA stones. Two struvite stones were considered to contain cystine. One cystine stone, 1 mixed UA stone, 4

  14. Dual-source virtual non-contrast CT of the head: a preliminary study

    International Nuclear Information System (INIS)

    Huang Wei; Xu Yiming; Shao Jin

    2011-01-01

    Objective: To investigate image quality and clinical value of dual-source dual energy virtual non-contrast (VNC) CT of the head. Methods: Sixty-two patients suspected of cerebrovascular diseases underwent conventional non-contrast (CNC) CT and dual energy CTA examination of the head with dual-source CT. Virtual non-contrast images were reconstructed using dual energy software. The CT values of gray matter, white matter, cerebrospinal fluid, hyperdense hemorrhagic lesion and hypodense ischemic lesion were compared between CNC and VNC images. A four-score scale was used to assess image quality subjectively. Image noise, radiation dosage and detection rate were compared between CNC and VNC images. Paired t test, Wilcoxon signed ranks test and Chi-square test (McNemar test and Kappa test) were used. Results: The CT value on CNC and VNC images, were (43.3±1.5) and (33.2±1.3) HU for gray matter (t=46.98, P 0.05, Kappa = 1.000) at per-patient level. Twenty-two patients with hypodense ischemic lesions were found on VNC images with one false positive case and two false negative cases. The sensitivity, specificity, positive predictive value and negative predictive value were 91.3% (21/23), 97.4% (38/39), 95.5% (21/22) and 95.0% (38/40) respectively. No statistical difference was found in detecting hypodense lesions between VNC and CNC images (χ 2 = 0.00, P>0.05, Kappa = 0.895). In per-lesion analysis, 53 hemorrhage lesions were found on VNC images with false negative results of four lesions and no false positive result. The sensitivity, specificity, positive predictive value and negative predictive value were 93.0% (53/57). 100.0% (38/38), 100.0% (53/.53) and 90.5% (38/42) respectively. There was no significant difference in detection rate of hyperdense lesion between VNC and CNC images (χ 2 = 2.25, P>0.05, Kappa = 0.914). Thirty-eight hypodense lesions were found on VNC images with 2 false positive lesions and 13 false negative lesions. The sensitivity, specificity

  15. Ion heating and energy partition at the heliospheric termination shock: hybrid simulations and analytical model

    Energy Technology Data Exchange (ETDEWEB)

    Gary, S Peter [Los Alamos National Laboratory; Winske, Dan [Los Alamos National Laboratory; Wu, Pin [BOSTON UNIV.; Schwadron, N A [BOSTON UNIV.; Lee, M [UNIV OF NEW HAMPSHIRE

    2009-01-01

    The Los Alamos hybrid simulation code is used to examine heating and the partition of dissipation energy at the perpendicular heliospheric termination shock in the presence of pickup ions. The simulations are one-dimensional in space but three-dimensional in field and velocity components, and are carried out for a range of values of pickup ion relative density. Results from the simulations show that because the solar wind ions are relatively cold upstream, the temperature of these ions is raised by a relatively larger factor than the temperature of the pickup ions. An analytic model for energy partition is developed on the basis of the Rankine-Hugoniot relations and a polytropic energy equation. The polytropic index {gamma} used in the Rankine-Hugoniot relations is varied to improve agreement between the model and the simulations concerning the fraction of downstream heating in the pickup ions as well as the compression ratio at the shock. When the pickup ion density is less than 20%, the polytropic index is about 5/3, whereas for pickup ion densities greater than 20%, the polytropic index tends toward 2.2, suggesting a fundamental change in the character of the shock, as seen in the simulations, when the pickup ion density is large. The model and the simulations both indicate for the upstream parameters chosen for Voyager 2 conditions that the pickup ion density is about 25% and the pickup ions gain the larger share (approximately 90%) of the downstream thermal pressure, consistent with Voyager 2 observations near the shock.

  16. Full field image reconstruction is suitable for high-pitch dual-source computed tomography.

    Science.gov (United States)

    Mahnken, Andreas H; Allmendinger, Thomas; Sedlmair, Martin; Tamm, Miriam; Reinartz, Sebastian D; Flohr, Thomas

    2012-11-01

    The field of view (FOV) in high-pitch dual-source computed tomography (DSCT) is limited by the size of the second detector. The goal of this study was to develop and evaluate a full FOV image reconstruction technique for high-pitch DSCT. For reconstruction beyond the FOV of the second detector, raw data of the second system were extended to the full dimensions of the first system, using the partly existing data of the first system in combination with a very smooth transition weight function. During the weighted filtered backprojection, the data of the second system were applied with an additional weighting factor. This method was tested for different pitch values from 1.5 to 3.5 on a simulated phantom and on 25 high-pitch DSCT data sets acquired at pitch values of 1.6, 2.0, 2.5, 2.8, and 3.0. Images were reconstructed with FOV sizes of 260 × 260 and 500 × 500 mm. Image quality was assessed by 2 radiologists using a 5-point Likert scale and analyzed with repeated-measure analysis of variance. In phantom and patient data, full FOV image quality depended on pitch. Where complete projection data from both tube-detector systems were available, image quality was unaffected by pitch changes. Full FOV image quality was not compromised at pitch values of 1.6 and remained fully diagnostic up to a pitch of 2.0. At higher pitch values, there was an increasing difference in image quality between limited and full FOV images (P = 0.0097). With this new image reconstruction technique, full FOV image reconstruction can be used up to a pitch of 2.0.

  17. Diagnostic accuracy of dual-source CT coronary angiography in patients with atrial fibrillation: Meta analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Gang, E-mail: cjr.sungang@vip.163.com [Department of Medical Imaging, Jinan Military General Hospital, No. 25, Shifan Road, Jinan, Shandong Province 250031 (China); Li, Min [Department of Medical Imaging, Jinan Military General Hospital, No. 25, Shifan Road, Jinan, Shandong Province 250031 (China); Jiang, Zhi-wei [Department of Health Statistics, School of Public Health, Fourth Military Medical University, No. 169, Changle West Road, Xi’an, Shaanxi 710032 (China); Xu, Lin [Department of Medical Cardiology, Jinan Military General Hospital, No. 25, Shifan Road, Jinan, Shandong Province 250031 (China); Peng, Zhao-hui; Ding, Juan; Li, Li [Department of Medical Imaging, Jinan Military General Hospital, No. 25, Shifan Road, Jinan, Shandong Province 250031 (China); Jin, Zhi-tao [Department of Cardiology, General Hospital of the Second Artillery, Beijing 100088 (China)

    2013-10-01

    Rationale and objective: To synthesize the available data to underscore the diagnostic accuracy of dual-source CT (DSCT) coronary angiography in patients with atrial fibrillation (AF). Materials and methods: We searched in the electronic databases of PubMed for all published studies that examined patients with AF using DSCT. We used an exact binomial rendition of the bivariate mixed-effects regression model to synthesize the diagnostic data. Results: The positive and negative likelihood ratios (LRs) at the patient level were 6.0 (CI, 3.6–10.1) and 0.03(CI, 0.004–0.2), respectively. The negative predictive values higher than 90% were available for a CAD prevalence <78%. The pooled vessel- and segment-level estimates showed higher positive and negative LRs than the patient-level estimates (15.3 [CI, 9.8–23.9] and 0.1 [CI, 0.07–0.3]; 25.1 [CI, 10.8–58.5] and 0.2 [CI, 0.2–0.3], respectively). No statistically significant heterogeneity between studies and publication bias were found at the patient level estimate. A sensitivity analysis showed that no study influenced the pooled results larger than 0.02. Conclusions: Cardiac angiography with DSCT can be applied as an imaging test for ruling out CAD in patient with AF. However, DSCT angiography may be not an effective tool for risk stratification for the high negative LR at the artery and segment levels.

  18. Clinical performance of dual-source computerized tomography (DSCT) in primary diagnostics of coronary heart diseases

    International Nuclear Information System (INIS)

    Brunner, H.; Froehner, S.; Wagner, M.; Schmitt, R.; Brunn, J.; Gietzen, F.H.; Kerber, S.

    2008-01-01

    Dual-source-CT-technology (DSCT) improves temporal resolution of cardiac computed tomography to 83 ms per heart-phase. In this study, the clinical performance of this new method is evaluated. Materials and Methods: In fifty patients (33 male, 17 female; age 50±13 years) with suspected coronary heart disease, CT angiography (slice thickness 0,75 mm, contrast-agent 60-80 ml iomeprol) was performed with a Somatom Definition scanner. Based on the coronary 15-segment-model of the AHA, scores for image quality and lumen reduction were established to enable the observer, to give recommendations for further therapy. Results: Out of 750 possible AHA-segments, 655 were depicted (87,3%). 591 segments (90,2%) were assessed without any limitation of quality, 49 (7,5%) segments showed moderate, and 15 (2,3%) segments severe limitation in image quality. 508 (77,6%) segments were without pathological findings, 92 (14,0%) segments had minimal atherosclerotic lesions, 42 (6,4%) segments suffered from stenoses with lumen reduction less than 70%, and 13 (2,0%) showed significant stenoses of more than 70%. In 31 patients (62%), coronary heart disease was ruled out by CT angiography without any need for further non-invasive or invasive diagnostics. 8 patients (16%) underwent stress-testing for ischemia. In 11 (22%) patients coronary angiography was recommended, and DSCT findings were confirmed in 10 cases. Only one LCx stenosis was overestimated in DSCT. Conclusion: Contrast-enhanced DSCT is a powerful tool in diagnosis of coronary heart disease. 98% of coronary segments could be assessed in diagnostic quality, and at least 90% of haemodynamically significant coronary stenoses were detected. (orig.)

  19. Quantitative assessment of pure aortic valve regurgitation with dual-source CT

    Energy Technology Data Exchange (ETDEWEB)

    Li, Z., E-mail: lzlcd01@126.com [Department of Radiology, West China Hospital, Sichuan University, 37 Guo Xue Xiang, Chengdu, Sichuan 610041 (China); Huang, L.; Chen, X.; Xia, C.; Yuan, Y.; Shuai, T. [Department of Radiology, West China Hospital, Sichuan University, 37 Guo Xue Xiang, Chengdu, Sichuan 610041 (China)

    2012-07-15

    Aim: To assess the severity of pure aortic regurgitation by measuring regurgitation volumes (RV) and fractions (RF) with dual-source computed tomography (DSCT) as compared to magnetic resonance imaging (MRI) and echocardiography. Materials and methods: Thirty-eight patients (15 men, 23 women; mean age 46 {+-} 11 years) with isolated aortic valve regurgitation underwent retrospectively electrocardiogram (ECG)-gated DSCT, echocardiography, and MRI. Stroke volumes of the left and right ventricles were measured at DSCT and MRI. Thus, RVs and RFs were calculated and compared. The agreement between DSCT and MRI was tested by intraclass correlation coefficient and Bland-Altman analyses. Spearman's rank order correlation and weighted {kappa} tests were used for testing correlations of AR severity between DSCT results and corresponding echocardiographic grades. Results: The RV and RF measured by DSCT were not significantly different from those measured using MRI (p = 0.71 and 0.79). DSCT correlated well with MRI for the measurement of RV (r{sub I} = 0.86, p<0.001) and calculation of the RF (r{sub I} =0.90, p<0.001). Good agreement between the techniques was obtained by using Bland-Altman analyses. The severity of regurgitation estimated by echocardiography correlated well with DSCT (r{sub s} = 0.95, p<0.001) and MRI (r{sub s} = 0.95, p<0.001). Inter-technique agreement between DSCT and two-dimensional transthoracic echocardiography (2DTTE) regarding the grading of the severity of AR was excellent ({kappa} = 0.90), and good agreement was also obtained between MRI and 2DTTE assessments of the severity of AR ({kappa} = 0.87). Conclusion: DSCT using a volume approach can be used to quantitatively determine the severity of pure aortic regurgitation when compared with MRI and echocardiography.

  20. Scanning protocol of dual-source computed tomography for aortic dissection

    International Nuclear Information System (INIS)

    Zhai Mingchun; Wang Yongmei

    2013-01-01

    Objective: To find a dual-source CT scanning protocol which can obtain high image quality with low radiation dose for diagnosis of aortic dissection. Methods: Total 120 patients with suspected aortic dissection were randomly and equally assigned into three groups. Patients in Croup A were performed CTA exam with prospectively electrocardiogram- gated high pitch spiral mode (FLASH). Patients in Croup B were performed CTA exam with retrospective electrocardiogram- gated spiral mode. Patients in Croup C were performed CTA exam with conventional mode which no electrocardiogram-gated. The image quality, radiation dose, advantages and disadvantages among the three scan protocol were analyzed. Results: For image quality, seventeen, twenty two and one patients in group A were granted to grade 1, 2, 3 respectively, and none was in grade 4; thirty three and seven patients in group B were granted to grade 1, 2, respectively, and none was in grade 3 and 4; fourteen and twenty six patients in group C were granted to grade 3, 4, respectively, and none was in grade 1 and 2. There was no significant difference between group A and B in image quality. Compared with the image quality, Group A and B were significantly higher than Group C. Mean effective radiation dose of Croup A, B and C were 7.7±0.4 mSv, 33.11±3.38 mSv, and 7.6±0.68 mSv, respectively. Group B was significantly higher than Groups A and C (P<0.05, P<0.05, respectively), and there was no significant difference between Group A and C (P=0.826). Conclusions: Prospectively electrocardiogram-gated high pitch spiral mode can be the first line protocol for evaluation of aortic dissection. It can achieve high image quality with low radiation dose. Conventional mode with no electrocardiogram-gated can be selectively used for Stanford B aortic dissection. (authors)

  1. Dual-source CT coronary imaging in heart transplant recipients: image quality and optimal reconstruction interval

    International Nuclear Information System (INIS)

    Bastarrika, Gorka; Arraiza, Maria; Pueyo, Jesus C.; Cecco, Carlo N. de; Ubilla, Matias; Mastrobuoni, Stefano; Rabago, Gregorio

    2008-01-01

    The image quality and optimal reconstruction interval for coronary arteries in heart transplant recipients undergoing non-invasive dual-source computed tomography (DSCT) coronary angiography was evaluated. Twenty consecutive heart transplant recipients who underwent DSCT coronary angiography were included (19 male, one female; mean age 63.1±10.7 years). Data sets were reconstructed in 5% steps from 30% to 80% of the R-R interval. Two blinded independent observers assessed the image quality of each coronary segments using a five-point scale (from 0 = not evaluative to 4=excellent quality). A total of 289 coronary segments in 20 heart transplant recipients were evaluated. Mean heart rate during the scan was 89.1±10.4 bpm. At the best reconstruction interval, diagnostic image quality (score ≥2) was obtained in 93.4% of the coronary segments (270/289) with a mean image quality score of 3.04± 0.63. Systolic reconstruction intervals provided better image quality scores than diastolic reconstruction intervals (overall mean quality scores obtained with the systolic and diastolic reconstructions 3.03±1.06 and 2.73±1.11, respectively; P<0.001). Different systolic reconstruction intervals (35%, 40%, 45% of RR interval) did not yield to significant differences in image quality scores for the coronary segments (P=0.74). Reconstructions obtained at the systolic phase of the cardiac cycle allowed excellent diagnostic image quality coronary angiograms in heart transplant recipients undergoing DSCT coronary angiography. (orig.)

  2. Dual-source CT coronary angiography in patients with premature heart-beats: initial experience

    International Nuclear Information System (INIS)

    Wang Yining; Zhang Zhuhua; Kong Lingyan; Song Lan; Mu Wenbin; Wang Yun; Jin Zhengyu

    2008-01-01

    Objective: To evaluate the feasibility of dual-source computed tomography (DSCT) coronary angiography in a population with premature heart-beats. Methods: Seventy patients with suspected coronary artery disease and premature heart-beats were routinely imaged on a DSCT scanner (Somatom Definition, Siemens AG, Germany). The images were reconstmcted before and after ECG editing. Two readers independently assessed image quality of all coronary segments using a four-point grading scale from excellent (1) to non-assessable (4). The results of the two groups were compared with a paired t-test, and a P value of less than 0.05 was considered significant. Results: The mean heart rate during examination ranged from 49 to 111 bpm[ mean(70.7±12.4) bpm]. Twenty-eight of 70 patients with relatively small variability of the heart rate [(41.0±18.4) bpm] got diagnostic image quality without ECG editing. In other 42 patients with larger variability of the heart rate [(71.4±28.7) bpm], the mean image quality scores were 2.09±1.27 and 1.50±0.79 before and after ECG editing, there was a significant difference (t= 13.764, P 2 =121.846, P<0.01). Finally, the diagnostic image accounted 98.0% (1014/1035) in all segments of 70 patients. Conclusion: DSCT can provide diagnostic images for patients with premature heart-beats. The image quality in patients with larger variability of the heart rate can be significantly improved through ECG editing. (authors)

  3. Image quality on dual-source computed-tomographic coronary angiography

    International Nuclear Information System (INIS)

    Rixe, Johannes; Rolf, Andreas; Conradi, Guido; Elsaesser, Albrecht; Moellmann, Helge; Nef, Holger M.; Hamm, Christian W.; Dill, Thorsten; Bachmann, Georg

    2008-01-01

    Multi-detector CT reliably permits visualization of coronary arteries, but due to the occurrence of motion artefacts at heart rates >65 bpm caused by a temporal resolution of 165 ms, its utilisation has so far been limited to patients with a preferably low heart rate. We investigated the assessment of image quality on computed tomography of coronary arteries in a large series of patients without additional heart rate control using dual-source computed tomography (DSCT). DSCT (Siemens Somatom Definition, 83-ms temporal resolution) was performed in 165 consecutive patients (mean age 64±11.4 years) after injection of 60-80 ml of contrast. Data sets were reconstructed in 5% intervals of the cardiac cycle and evaluated by two readers in consensus concerning evaluability of the coronary arteries and presence of motion and beam-hardening artefacts using the AHA 16-segment coronary model. Mean heart rate during CT was 65±10.5 bpm; visualisation without artefacts was possible in 98.7% of 2,541 coronary segments. Only two segments were considered unevaluable due to cardiac motion; 30 segments were unassessable due to poor signal-to-noise ratio or coronary calcifications (both n=15). Data reconstruction at 65-70% of the cardiac cycle provided for the best image quality. For heart rates >85 bpm, a systolic reconstruction at 45% revealed satisfactory results. Compared with earlier CT generations, DSCT provides for non-invasive coronary angiography with diagnostic image quality even at heart rates >65 bpm and thus may broaden the spectrum of patients that can be investigated non-invasively. (orig.)

  4. Dual-Source Linear Energy Prediction (LINE-P) Model in the Context of WSNs.

    Science.gov (United States)

    Ahmed, Faisal; Tamberg, Gert; Le Moullec, Yannick; Annus, Paul

    2017-07-20

    Energy harvesting technologies such as miniature power solar panels and micro wind turbines are increasingly used to help power wireless sensor network nodes. However, a major drawback of energy harvesting is its varying and intermittent characteristic, which can negatively affect the quality of service. This calls for careful design and operation of the nodes, possibly by means of, e.g., dynamic duty cycling and/or dynamic frequency and voltage scaling. In this context, various energy prediction models have been proposed in the literature; however, they are typically compute-intensive or only suitable for a single type of energy source. In this paper, we propose Linear Energy Prediction "LINE-P", a lightweight, yet relatively accurate model based on approximation and sampling theory; LINE-P is suitable for dual-source energy harvesting. Simulations and comparisons against existing similar models have been conducted with low and medium resolutions (i.e., 60 and 22 min intervals/24 h) for the solar energy source (low variations) and with high resolutions (15 min intervals/24 h) for the wind energy source. The results show that the accuracy of the solar-based and wind-based predictions is up to approximately 98% and 96%, respectively, while requiring a lower complexity and memory than the other models. For the cases where LINE-P's accuracy is lower than that of other approaches, it still has the advantage of lower computing requirements, making it more suitable for embedded implementation, e.g., in wireless sensor network coordinator nodes or gateways.

  5. Desired lifetime and end-of-life desires across adulthood from 20 to 90: a dual-source information model.

    Science.gov (United States)

    Lang, Frieder R; Baltes, Paul B; Wagner, Gert G

    2007-09-01

    How long do people want to live, and how does scientific research on aging affect such desires? A dual-source information model proposes that aging expectations and desires are informed differently by two sources: personal experiences on the one hand, and scientific and societal influences on the other. Two studies with independent German national samples explored desires regarding length of life and end of life among adults between the ages of 20 and 90. FINDINGS ARE: First, desired lifetime is consistent at around 85 years with few age differences. Second, experimental induction of good or bad news from research on aging has little effect in Study 1. Third, interest in science has moderating effects on desired lifetime in Study 2. Fourth, there is a high prevalence of a strong desire to control the "when and how" of one's death, although only 11% of the individuals completed a living will. Findings are consistent with the dual-source information model.

  6. A novel hybrid chaotic ant swarm algorithm for heat exchanger networks synthesis

    International Nuclear Information System (INIS)

    Zhang, Chunwei; Cui, Guomin; Peng, Fuyu

    2016-01-01

    Highlights: • The chaotic ant swarm algorithm is proposed to avoid trapping into a local optimum. • The organization variables update strategy makes full use of advantages of the chaotic search. • The structure evolution strategy is developed to handle integer variables optimization. • Overall three cases taken form the literatures are investigated with better optima. - Abstract: The heat exchanger networks synthesis (HENS) still remains an open problem due to its combinatorial nature, which can easily result in suboptimal design and unacceptable calculation effort. In this paper, a novel hybrid chaotic ant swarm algorithm is proposed. The presented algorithm, which consists of a combination of chaotic ant swarm (CAS) algorithm, structure evolution strategy, local optimization strategy and organization variables update strategy, can simultaneously optimize continuous variables and integer variables. The CAS algorithm chaotically searches and generates new solutions in the given space, and subsequently the structure evolution strategy evolves the structures represented by the solutions and limits the search space. Furthermore, the local optimizing strategy and the organization variables update strategy are introduced to enhance the performance of the algorithm. The study of three different cases, found in the literature, revealed special search abilities in both structure space and continuous variable space.

  7. Role of lower hybrid waves in ion heating at dipolarization fronts

    Science.gov (United States)

    Greco, A.; Artemyev, A.; Zimbardo, G.; Angelopoulos, V.; Runov, A.

    2017-05-01

    One of the important sources of hot ions in the magnetotail is the bursty bulk flows propagating away from the reconnection region and heating the ambient plasma. Charged particles interact with nonlinear magnetic field pulses (dipolarization fronts, DFs) embedded into these flows. The convection electric fields associated with DF propagation are known to reflect and accelerate ambient ions. Moreover, a wide range of waves is observed within/near these fronts, the electric field fluctuations being dominated by the lower hybrid drift (LHD) instability. Here we investigate the potential role of these waves in the further acceleration of ambient ions. We use a LHD wave emission profile superimposed on the leading edge of a two-dimensional model profile of a DF and a test particle approach. We show that LHD waves with realistic amplitudes can significantly increase the upper limit of energies gained by ions. Wave-particle interaction near the front is more effective in producing superthermal ions than in increasing the flux of thermal ions. Comparison of test particle simulations and Time History of Events and Macroscale Interactions during Substorms observations show that ion acceleration by LHD waves is more important for slower DFs.

  8. Lower hybrid heating and current drive in Iter operation scenarios and outline system design

    International Nuclear Information System (INIS)

    1994-11-01

    Lower Hybrid Waves (LHW) are considered a valid method of plasma heating and the best demonstrated current drive method. Current drive by LHW possesses the unique feature, as compared to the other methods, to retain a good current drive efficiency in plasma regions of low to medium temperature, or in low-β phases of the discharges. This makes them an essential element to realize the so called 'advanced steady-state Tokamak scenarios' in which a hollow current density profile (deep shear reversal) - established during the ramp-up of the plasma current - offers the prospects of improved confinement and an MHD-stable route to continuous burn. This report contains both modelling and design studies of an LHW system for ITER. It aims primarily at the definition of concepts and parameters for steady-state operation using LHW combined with Fast Waves (FW), or other methods of generating a central seed current for high bootstrap current operation. However simulations addressing the use of LHW for current profile control in the high current pulsed operation scenario are also presented. The outline design of a LHW system which covers the needs for both pulsed and steady-state operation is described in detail. (author). 28 refs., 49 figs

  9. Performance of turbo high-pitch dual-source CT for coronary CT angiography: first ex vivo and patient experience

    Energy Technology Data Exchange (ETDEWEB)

    Morsbach, Fabian; Gordic, Sonja; Husarik, Daniela; Frauenfelder, Thomas; Alkadhi, Hatem [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zurich (Switzerland); Desbiolles, Lotus; Leschka, Sebastian [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zurich (Switzerland); Kantonsspital St. Gallen, Divison of Radiology and Nuclear Medicine, St. Gallen (Switzerland); Schmidt, Bernhard; Allmendinger, Thomas [Siemens AG, Healthcare Sector, Forchheim (Germany); Wildermuth, Simon [Kantonsspital St. Gallen, Divison of Radiology and Nuclear Medicine, St. Gallen (Switzerland)

    2014-08-15

    To evaluate image quality, maximal heart rate allowing for diagnostic imaging, and radiation dose of turbo high-pitch dual-source coronary computed tomographic angiography (CCTA). First, a cardiac motion phantom simulating heart rates (HRs) from 60-90 bpm in 5-bpm steps was examined on a third-generation dual-source 192-slice CT (prospective ECG-triggering, pitch 3.2; rotation time, 250 ms). Subjective image quality regarding the presence of motion artefacts was interpreted by two readers on a four-point scale (1, excellent; 4, non-diagnostic). Objective image quality was assessed by calculating distortion vectors. Thereafter, 20 consecutive patients (median, 50 years) undergoing clinically indicated CCTA were included. In the phantom study, image quality was rated diagnostic up to the HR75 bpm, with object distortion being 1 mm or less. Distortion increased above 1 mm at HR of 80-90 bpm. Patients had a mean HR of 66 bpm (47-78 bpm). Coronary segments were of diagnostic image quality for all patients with HR up to 73 bpm. Average effective radiation dose in patients was 0.6 ± 0.3 mSv. Our combined phantom and patient study indicates that CCTA with turbo high-pitch third-generation dual-source 192-slice CT can be performed at HR up to 75 bpm while maintaining diagnostic image quality, being associated with an average radiation dose of 0.6 mSv. (orig.)

  10. Adult congenital heart disease imaging with second-generation dual-source computed tomography: initial experiences and findings.

    Science.gov (United States)

    Ghoshhajra, Brian B; Sidhu, Manavjot S; El-Sherief, Ahmed; Rojas, Carlos; Yeh, Doreen Defaria; Engel, Leif-Christopher; Liberthson, Richard; Abbara, Suhny; Bhatt, Ami

    2012-01-01

    Adult congenital heart disease patients present a unique challenge to the cardiac imager. Patients may present with both acute and chronic manifestations of their complex congenital heart disease and also require surveillance for sequelae of their medical and surgical interventions. Multimodality imaging is often required to clarify their anatomy and physiology. Radiation dose is of particular concern in these patients with lifelong imaging needs for their chronic disease. The second-generation dual-source scanner is a recently available advanced clinical cardiac computed tomography (CT) scanner. It offers a combination of the high-spatial resolution of modern CT, the high-temporal resolution of dual-source technology, and the wide z-axis coverage of modern cone-beam geometry CT scanners. These advances in technology allow novel protocols that markedly reduce scan time, significantly reduce radiation exposure, and expand the physiologic imaging capabilities of cardiac CT. We present a case series of complicated adult congenital heart disease patients imaged by the second-generation dual-source CT scanner with extremely low-radiation doses and excellent image quality. © 2012 Wiley Periodicals, Inc.

  11. High-pitch dual-source CT angiography of the whole aorta without ECG synchronisation: Initial experience

    International Nuclear Information System (INIS)

    Beeres, Martin; Schell, Boris; Mastragelopoulos, Aristidis; Kerl, Josef Matthias; Gruber-Rouh, Tatjana; Lee, Clara; Siebenhandl, Petra; Bodelle, Boris; Zangos, Stephan; Vogl, Thomas J.; Jacobi, Volkmar; Bauer, Ralf W.; Herrmann, Eva

    2012-01-01

    To investigate the feasibility, image quality and radiation dose for high-pitch dual-source CT angiography (CTA) of the whole aorta without ECG synchronisation. Each group of 40 patients underwent CTA either on a 16-slice (group 1) or dual-source CT device with conventional single-source (group 2) or high-pitch mode with a pitch of 3.0 (group 3). The presence of motion or stair-step artefacts of the thoracic aorta was independently assessed by two readers. Subjective and objective scoring of motion and artefacts were significantly reduced in the high-pitch examination protocol (p < 0.05). The imaging length was not significantly different, but the imaging time was significantly (p < 0.001) shorter in the high-pitch group (12.2 vs. 7.4 vs. 1.7 s for groups 1, 2 and 3). The ascending aorta and the coronary ostia were reliably evaluable in all patients of group 3 without motion artefacts as well. High-pitch dual-source CT angiography of the whole aorta is feasible in unselected patients. As a significant advantage over regular pitch protocols, motion-free imaging of the aorta is possible without ECG synchronisation. Thus, this CT mode bears potential to become a standard CT protocol before trans-catheter aortic valve implantation (TAVI). (orig.)

  12. Performance of turbo high-pitch dual-source CT for coronary CT angiography: first ex vivo and patient experience

    International Nuclear Information System (INIS)

    Morsbach, Fabian; Gordic, Sonja; Husarik, Daniela; Frauenfelder, Thomas; Alkadhi, Hatem; Desbiolles, Lotus; Leschka, Sebastian; Schmidt, Bernhard; Allmendinger, Thomas; Wildermuth, Simon

    2014-01-01

    To evaluate image quality, maximal heart rate allowing for diagnostic imaging, and radiation dose of turbo high-pitch dual-source coronary computed tomographic angiography (CCTA). First, a cardiac motion phantom simulating heart rates (HRs) from 60-90 bpm in 5-bpm steps was examined on a third-generation dual-source 192-slice CT (prospective ECG-triggering, pitch 3.2; rotation time, 250 ms). Subjective image quality regarding the presence of motion artefacts was interpreted by two readers on a four-point scale (1, excellent; 4, non-diagnostic). Objective image quality was assessed by calculating distortion vectors. Thereafter, 20 consecutive patients (median, 50 years) undergoing clinically indicated CCTA were included. In the phantom study, image quality was rated diagnostic up to the HR75 bpm, with object distortion being 1 mm or less. Distortion increased above 1 mm at HR of 80-90 bpm. Patients had a mean HR of 66 bpm (47-78 bpm). Coronary segments were of diagnostic image quality for all patients with HR up to 73 bpm. Average effective radiation dose in patients was 0.6 ± 0.3 mSv. Our combined phantom and patient study indicates that CCTA with turbo high-pitch third-generation dual-source 192-slice CT can be performed at HR up to 75 bpm while maintaining diagnostic image quality, being associated with an average radiation dose of 0.6 mSv. (orig.)

  13. New hybrid nanofluid containing encapsulated paraffin wax and sand nanoparticles in propylene glycol-water mixture: Potential heat transfer fluid for energy management

    International Nuclear Information System (INIS)

    Manikandan, S.; Rajan, K.S.

    2017-01-01

    Highlights: • Hybrid nanofluid containing sand nanoparticles & encapsulated paraffin wax prepared. • Specific heat of hybrid nanofluid 9% greater than that of PG-water mixture. • Specific heat & thermal conductivity enhanced at optimum paraffin wax concentration. • Hybrid nanofluid with 1 wt.% paraffin wax & 1 vol% sand nanoparticles best suited. - Abstract: The reduction in specific heat commonly encountered due to the addition of nanoparticles to a heat transfer fluid such as propylene glycol-water mixture, can be overcome by co-dispersing surfactant-encapsulated paraffin wax, leading to formation of a hybrid nanofluid. Experimental investigations have been carried out on the preparation and evaluation of thermophysical properties of a hybrid nanofluid containing pluronic P-123 encapsulated paraffin wax (70–120 nm diameter, 1–5 wt.%) and sand nanoparticles (1 vol%) in propylene glycol-water mixture. The comparison of results of differential scanning calorimetry of pure paraffin wax and encapsulated paraffin wax revealed encapsulation efficiency of 84.4%. The specific heat of hybrid nanofluids monotonously increased with paraffin wax concentration, with 9.1% enhancement in specific heat for hybrid nanofluid containing 5 wt.% paraffin wax, in comparison to propylene glycol-water mixture. There exists an optimum paraffin wax concentration (1 wt.%) for the hybrid nanofluid at which the combination of various thermophysical properties such as specific heat, thermal conductivity and viscosity are favorable for use as heat transfer fluid. Such a hybrid nanofluid can be used as a substitute for propylene glycol-water mixture in solar thermal systems.

  14. Formation of inorganic nanofibers by heat-treatment of poly(vinyl alcohol-zirconium compound hybrid nanofibers

    Directory of Open Access Journals (Sweden)

    Nakane K.

    2013-01-01

    Full Text Available Poly(vinyl alcohol-zirconium compound hybrid nanofibers (precursors were formed by electrospinning employing water as a solvent for the spinning solution. The precursors were converted into oxide (ZrO2, carbide (ZrC or nitride (ZrN nanofibers by heating them in air, Ar or N2 atmospheres. Monoclinic ZrO2 nanofibers with high-specific surface area were obtained by heat-treatment of the precursors in air. ZrC and ZrN nanofibers could be obtained below theoretical temperatures calculated from thermodynamics data.

  15. Simulation of the thermal performance of a hybrid solar-assisted ground-source heat pump system in a school building

    Science.gov (United States)

    Androulakis, N. D.; Armen, K. G.; Bozis, D. A.; Papakostas, K. T.

    2018-04-01

    A hybrid solar-assisted ground-source heat pump (SAGSHP) system was designed, in the frame of an energy upgrade study, to serve as a heating system in a school building in Greece. The main scope of this study was to examine techniques to reduce the capacity of the heating equipment and to keep the primary energy consumption low. Simulations of the thermal performance of both the building and of five different heating system configurations were performed by using the TRNSYS software. The results are presented in this work and show that the hybrid SAGSHP system displays the lower primary energy consumption among the systems examined. A conventional ground-source heat pump system has the same primary energy consumption, while the heat pump's capacity is double and the ground heat exchanger 2.5 times longer. This work also highlights the contribution of simulation tools to the design of complex heating systems with renewable energy sources.

  16. Numerical investigation of heat pipe-based photovoltaic–thermoelectric generator (HP-PV/TEG) hybrid system

    International Nuclear Information System (INIS)

    Makki, Adham; Omer, Siddig; Su, Yuehong; Sabir, Hisham

    2016-01-01

    Highlights: • Integration of TE generators with a heat pipe-based PV module as a hybrid system is proposed. • Numerical transient modeling based on the energy balance equations of the system was performed. • Integration of TE generators with PV module aid operating the solar cells at a steady level in harsh conditions. - Abstract: Photovoltaic (PV) cells are able to absorb about 80% of the solar spectral irradiance, however, certain percentage accounts for electricity conversion depending on the cell technology employed. The remainder energy however, can elevate the silicon junction temperature in the PV encapsulation perilously, resulting in deteriorated performance. Temperature rise at the PV cell level is addressed as one of the most critical issues that can seriously degrade and shortens the life-time of the PV cells, hence thermal management of the PV module during operation is considered essential. Hybrid PV designs which are able to simultaneously generate electrical energy and utilize the waste heat have been proven to be the most promising solution. In this study, theoretical investigation of a hybrid system comprising of thermoelectric generator integration with a heat pipe-based Photovoltaic/Thermal (PV/T) absorber is proposed and evaluated. The system presented incorporates a PV panel for direct electricity generation, a heat pipe for excessive heat absorption from the PV cells and a thermoelectric generator (TEG) performing direct heat-to-electricity conversion. A mathematical model based on the energy balance within the system is developed to evaluate the performance of the hybrid integration and the improvements associated with the thermal management of PV cells. Results are presented in terms of the overall system efficiency compared to a conventional PV panel under identical operating conditions. The integration of TEG modules with PV cells in such way aid improving the performance of the PV cells in addition to utilizing the waste-heat

  17. Effect of high-pitch dual-source CT to compensate motion artifacts: a phantom study.

    Science.gov (United States)

    Farshad-Amacker, Nadja A; Alkadhi, Hatem; Leschka, Sebastian; Frauenfelder, Thomas

    2013-10-01

    To evaluate the potential of high-pitch, dual-source computed tomography (DSCT) for compensation of motion artifacts. Motion artifacts were created using a moving chest/cardiac phantom with integrated stents at different velocities (from 0 to 4-6 cm/s) parallel (z direction), transverse (x direction), and diagonal (x and z direction combined) to the scanning direction using standard-pitch (SP) (pitch = 1) and high-pitch (HP) (pitch = 3.2) 128-detector DSCT (Siemens, Healthcare, Forchheim, Germany). The scanning parameters were (SP/HP): tube voltage, 120 kV/120 kV; effective tube current time product, 300 mAs/500 mAs; and a pitch of 1/3.2. Motion artifacts were analyzed in terms of subjective image quality and object distortion. Image quality was rated by two blinded, independent observers using a 4-point scoring system (1, excellent; 2, good with minor object distortion or blurring; 3, diagnostically partially not acceptable; and 4, diagnostically not acceptable image quality). Object distortion was assessed by the measured changes of the object's outer diameter (x) and length (z) and a corresponding calculated distortion vector (d) (d = √(x(2) + z(2))). The interobserver agreement was excellent (k = 0.91). Image quality using SP was diagnostically not acceptable with any motion in x direction (scores 3 and 4), in contrast to HP DSCT where it remained diagnostic up to 2 cm/s (scores 1 and 2). For motion in the z direction only, image quality remained diagnostic for SP and HP DSCT (scores 1 and 2). Changes of the object's diameter (x), length (z), and distortion vectors (d) were significantly greater with SP (overall: x = 1.9 cm ± 1.7 cm, z = 0.6 cm ± 0.8 cm, and d = 1.4 cm ± 1.5 cm) compared to HP DSCT (overall: x = 0.1 cm ± 0.1 cm, z = 0.0 cm ± 0.1 cm, and d = 0.1 cm ± 0.1 cm; each P pitch DSCT significantly decreases motion artifacts in various directions and improves image quality. Copyright © 2013 AUR. Published by Elsevier Inc. All rights reserved.

  18. Cardiac dual-source CT for the preoperative assessment of patients undergoing bariatric surgery

    International Nuclear Information System (INIS)

    Tognolini, A.; Arellano, C.S.; Marfori, W.; Sayre, J.W.; Hollada, J.L.; Goldin, J.G.; Dutson, E.P.; Ruehm, S.G.

    2013-01-01

    Aim: To assess the diagnostic value of coronary dual-source computed tomography (DSCT) as a comprehensive, non-invasive tool in the preoperative cardiac evaluation of patients undergoing bariatric surgery. Materials and methods: Thirty consecutive obese [average body mass index (BMI): 45 ± 7.6, range: 35–59] patients (24 women; six men; median age: 52 ± 15 years) were enrolled in this institutional review board (IRB)-approved, Health Insurance Portability and Accountability Act of 1996 (HIPAA)-compliant prospective study. Calcium scoring (CaS) and electrocardiography (ECG)-gated images of the coronary arteries were obtained with a large body habitus protocol (120 kV; 430 mAs; 100 ml iodinated contrast medium at 7 ml/s injection rate) on a DSCT machine. Qualitative (four-point: 1 = excellent to 4 = not delineable) coronary segmental analysis, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) measurements were performed. The presence and degree of vascular disease (four-grade scale: mild to severe) was correlated with CaS and cardiovascular (CV) risk stratification blood tests. In patients with severe stenosis (>70%), findings were compared with cardiac nuclear medicine imaging (single photon-emission computed tomography; SPECT) imaging. Results: The average HR, enhancement, and quality score were 64 ± 7 beats/min, 288 ± 66 HU and 1.8 ± .5, respectively. Ninety-three percent (417/450) of the coronary segments were rated diagnostic. The SNRs and CNRs were 17 ± 9 and 12 ± 7 for the right coronary artery; 17 ± 8 and 12 ± 7 for the left main coronary artery; 16 ± 9 and 11 ± 7 for the left anterior descending coronary artery; and 15 ± 7 and 10 ± 6 for the left circumflex coronary artery. Ten of the 30 patients (33%) demonstrated coronary artery disease (CAD) of which two (6%) showed three-vessel disease. Four (13%) patients showed severe disease: in three of which the presence of significant stenosis was confirmed by SPECT and by catheter

  19. Assessment of left ventricular function and mass in dual-source computed tomography coronary angiography

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Christoph J., E-mail: c.jensen@contilia.d [Department of Cardiology and Angiology, Elisabeth Hospital, Essen (Germany); Jochims, Markus [Department of Cardiology and Angiology, Elisabeth Hospital, Essen (Germany); Hunold, Peter; Forsting, Michael; Barkhausen, Joerg [Department of Diagnostic and Interventional Radiology and Neuroradiology, University of Essen (Germany); Sabin, Georg V.; Bruder, Oliver [Department of Cardiology and Angiology, Elisabeth Hospital, Essen (Germany); Schlosser, Thomas [Department of Diagnostic and Interventional Radiology and Neuroradiology, University of Essen (Germany)

    2010-06-15

    Purpose: To quantify left ventricular (LV) function and mass (LVM) derived from dual-source computed tomography (DSCT) and the influence of beta-blocker administration compared to cardiac magnetic resonance imaging (CMR). Methods: Thirty-two patients undergoing cardiac DSCT and CMR were included, where of fifteen received metoprolol intravenously before DSCT. LV parameters were calculated by the disc-summation method (DSM) and by a segmented region-growing algorithm (RGA). All data sets were analyzed by two blinded observers. Interobserver agreement was tested by the intraclass correlation coefficient. Results.: 1. Using DSM LV parameters were not statistically different between DSCT and CMR in all patients (DSCT vs. CMR: EF 63 {+-} 8% vs. 64 {+-} 8%, p = 0.47; EDV 136 {+-} 36 ml vs. 138 {+-} 35 ml, p = 0.66; ESV 52 {+-} 21 ml vs. 52 {+-} 22 ml, p = 0.61; SV 83 {+-} 22 ml vs. 87 {+-} 19 ml, p = 0.22; CO 5.4 {+-} 0.9 l/min vs. 5.7 {+-} 1.2 l/min, p = 0.09, LVM 132 {+-} 33 g vs. 132 {+-} 33 g, p = 0.99). 2. In a subgroup of 15 patients beta-blockade prior to DSCT resulted in a lower ejection fraction (EF), stroke volume (SV), cardiac output (CO) and increase in end systolic volume (ESV) in DSCT (EF 59 {+-} 8% vs. 62 {+-} 9%; SV 73 {+-} 17 ml vs. 81 {+-} 15 ml; CO 5.7 {+-} 1.2 l/min vs. 5.0 {+-} 0.8 l/min; ESV 52 {+-} 27 ml vs. 57 {+-} 24 ml, all p < 0.05). 3. Analyzing the RGA parameters LV volumes were not significantly different compared to DSM, whereas LVM was higher using RGA (177 {+-} 31 g vs. 132 {+-} 33 g, p < 0.05). Interobserver agreement was excellent comparing DSM values with best agreement between RGA calculations. Conclusion: Left ventricular volumes and mass can reliably be assessed by DSCT compared to CMR. However, beta-blocker administration leads to statistically significant reduced EF, SV and CO, whereas ESV significantly increases. DSCT RGA reliably analyzes LV function, whereas LVM is overestimated compared to DSM.

  20. Dual-Source Computed Tomography Evaluation of Children with Congenital Pulmonary Valve Stenosis

    International Nuclear Information System (INIS)

    Sun, Zhanguo; Xu, Wenjian; Huang, Shuran; Chen, Yueqin; Guo, Xiang; Shi, Zhitao

    2016-01-01

    Despite dual-source computed tomography (DSCT) technology has been performed well on adults or infants with heart disease, specific knowledge about children with congenital pulmonary valve stenosis (PS) remained to be established. This original research aimed to establish a professional approach of DSCT performing technology on children and to assess the image quality performed by DSCT to establish a diagnostic evaluation for children with PS. Ninety-eight children with congenital PS referred to affiliated hospital of Jining medical college were recruited from October 2013 to March 2015. Participants were divided into four groups according to different ages (0 - 1, 1 - 3, 3 - 7, 7 - 14), or three groups according to different heart rates (< 90, 90 - 110, > 110). Image quality of pulmonary valves was assessed based on a four-point grading scale (1 - 4 points). Those cases achieving a score of ≥ 3 points were selected for further investigation, which played a critical role in our analysis. Correlation analysis was used to identify the effects of age and heart rate on image quality. Additionally, the results evaluated by DSCT were compared with those evaluated from the operation, further confirming the accuracy of DSCT. Seventy-two cases (73.4%) achieved a score of ≥ 3 points based on pulmonary valve imaging, which were available for further diagnosis. There was a statistically significant difference (P < 0.05) between the four groups except 0 - 1 group and 1 - 3 group, 3 - 7 group and 7 - 14 group, and the image quality of elder group was higher than younger group. Image score was gradually decreased with increased heart rate (F = 19.05, P < 0.01). Heart rate was negatively correlated with pulmonary valve scores (r = -0.391, P < 0.001), while there was no correlation between age and scores (r = 0.185, P = 0.070). The number, shape, commissure, and opening status of pulmonary valves evaluated by DSCT were the same as the results of operation. Heart rate serves a

  1. Assessment of left ventricular function and mass in dual-source computed tomography coronary angiography

    International Nuclear Information System (INIS)

    Jensen, Christoph J.; Jochims, Markus; Hunold, Peter; Forsting, Michael; Barkhausen, Joerg; Sabin, Georg V.; Bruder, Oliver; Schlosser, Thomas

    2010-01-01

    Purpose: To quantify left ventricular (LV) function and mass (LVM) derived from dual-source computed tomography (DSCT) and the influence of beta-blocker administration compared to cardiac magnetic resonance imaging (CMR). Methods: Thirty-two patients undergoing cardiac DSCT and CMR were included, where of fifteen received metoprolol intravenously before DSCT. LV parameters were calculated by the disc-summation method (DSM) and by a segmented region-growing algorithm (RGA). All data sets were analyzed by two blinded observers. Interobserver agreement was tested by the intraclass correlation coefficient. Results.: 1. Using DSM LV parameters were not statistically different between DSCT and CMR in all patients (DSCT vs. CMR: EF 63 ± 8% vs. 64 ± 8%, p = 0.47; EDV 136 ± 36 ml vs. 138 ± 35 ml, p = 0.66; ESV 52 ± 21 ml vs. 52 ± 22 ml, p = 0.61; SV 83 ± 22 ml vs. 87 ± 19 ml, p = 0.22; CO 5.4 ± 0.9 l/min vs. 5.7 ± 1.2 l/min, p = 0.09, LVM 132 ± 33 g vs. 132 ± 33 g, p = 0.99). 2. In a subgroup of 15 patients beta-blockade prior to DSCT resulted in a lower ejection fraction (EF), stroke volume (SV), cardiac output (CO) and increase in end systolic volume (ESV) in DSCT (EF 59 ± 8% vs. 62 ± 9%; SV 73 ± 17 ml vs. 81 ± 15 ml; CO 5.7 ± 1.2 l/min vs. 5.0 ± 0.8 l/min; ESV 52 ± 27 ml vs. 57 ± 24 ml, all p < 0.05). 3. Analyzing the RGA parameters LV volumes were not significantly different compared to DSM, whereas LVM was higher using RGA (177 ± 31 g vs. 132 ± 33 g, p < 0.05). Interobserver agreement was excellent comparing DSM values with best agreement between RGA calculations. Conclusion: Left ventricular volumes and mass can reliably be assessed by DSCT compared to CMR. However, beta-blocker administration leads to statistically significant reduced EF, SV and CO, whereas ESV significantly increases. DSCT RGA reliably analyzes LV function, whereas LVM is overestimated compared to DSM.

  2. Heat transfer and entropy generation analysis of hybrid graphene/Fe3O4 ferro-nanofluid flow under the influence of a magnetic field

    DEFF Research Database (Denmark)

    Mehrali, Mohammad; Sadeghinezhad, Emad; Akhiani, Amir Reza

    2017-01-01

    oxide, iron salts and tannic acid as the reductant and stabilizer. The thermophysical and magnetic properties of the hybrid nanofluid have been widely characterized and thermal conductivity has shown an enhancement of 11%. The experimental results indicated that the heat transfer enhancement of hybrid...

  3. Thermal analysis of hybrid single-phase, two-phase and heat pump thermal control system (TCS) for future spacecraft

    International Nuclear Information System (INIS)

    Lee, S.H.; Mudawar, I.; Hasan, Mohammad M.

    2016-01-01

    Highlights: • Hybrid Thermal Control System (H-TCS) is proposed for future spacecraft. • Thermodynamic performance of H-TCS is examined for different space missions. • Operational modes including single-phase, two-phase and heat pump are explored. • R134a is deemed most appropriate working fluid. - Abstract: An urgent need presently exists to develop a new class of versatile spacecraft capable of conducting different types of missions and enduring varying gravitational and temperature environments, including Lunar, Martian and Near Earth Object (NEOs). This study concerns the spacecraft's Thermal Control System (TCS), which tackles heat acquisition, especially from crew and avionics, heat transport, and ultimate heat rejection by radiation. The primary goal of the study is to explore the design and thermal performance of a Hybrid Thermal Control System (H-TCS) that would satisfy the diverse thermal requirements of the different space missions. The H-TCS must endure both ‘cold’ and ‘hot’ environments, reduce weight and size, and enhance thermodynamic performance. Four different operational modes are considered: single-phase, two-phase, basic heat pump and heat pump with liquid-side, suction-side heat exchanger. A thermodynamic trade study is conducted for six different working fluids to assess important performance parameters including mass flow rate of the working fluid, maximum pressure, radiator area, compressor/pump work, and coefficient of performance (COP). R134a is determined to be most suitable based on its ability to provide a balanced compromise between reducing flow rate and maintaining low system pressure, and a moderate coefficient of performance (COP); this fluid is also both nontoxic and nonflammable, and features zero ozone depletion potential (ODP) and low global warming potential (GWP). It is shown how specific mission stages dictate which mode of operation is most suitable, and this information is used to size the radiator for the

  4. Noise-tolerance analysis for detection and reconstruction of absorbing inhomogeneities with diffuse optical tomography using single- and phase-correlated dual-source schemes

    International Nuclear Information System (INIS)

    Kanmani, B; Vasu, R M

    2007-01-01

    An iterative reconstruction procedure is used to invert intensity data from both single- and phase-correlated dual-source illuminations for absorption inhomogeneities. The Jacobian for the dual source is constructed by an algebraic addition of the Jacobians estimated for the two sources separately. By numerical simulations, it is shown that the dual-source scheme performs superior to the single-source system in regard to (i) noise tolerance in data and (ii) ability to reconstruct smaller and lower contrast objects. The quality of reconstructions from single-source data, as indicated by mean-square error at convergence, is markedly poorer compared to their dual-source counterpart, when noise in data was in excess of 2%. With fixed contrast and decreasing inhomogeneity diameter, our simulations showed that, for diameters below 7 mm, the dual-source scheme has a higher percentage contrast recovery compared to the single-source scheme. Similarly, the dual-source scheme reconstructs to a higher percentage contrast recovery from lower contrast inhomogeneity, in comparison to the single-source scheme

  5. Development of the Hybrid Operation Method of a Multi-Geothermal Heat Pump System and Absorption Chiller-Heater

    Directory of Open Access Journals (Sweden)

    Young-Ju Jung

    2015-08-01

    Full Text Available Considerable efforts have been made to reduce the energy consumption of buildings due to the energy crisis, and, the Korean government has supported the use of renewable energy through various grants. Among the possible renewable energy sources, geothermal energy can be used regardless of the outside weather. Therefore, energy consumption can be reduced considerably in summer and winter. Despite the increasing use of renewable energy, the use of renewables has not been operating appropriately. Therefore, this study examined some of the problems of the operation of renewable energy and some possible improvements. The aim of the study is to evaluate a building containing an actual installed multi-geothermal heat pump (Multi-GHP system, in terms of the energy efficiency. In addition, this study evaluated the present control system and the method of complex operation regarding existing heat sources systems and GHP systems through a simulation. The results can be regarded as the result of a hybrid operation method for the improvement of an existing operation. Therefore, the Multi-GHP system energy use of a hybrid operation condition of the Multi-GHP systems and the absorption (ABS chiller-heater system was reduced compared to the operation condition of the Multi-GHP system, and the total energy consumption of the heat source equipment was reduced. The proposed operation plan was evaluated after applying the system to a building. These results showed that the efficient operation of a Multi-GHP hybrid operation method is possible. As a result, the GHP energy use of Multi-GHP systems and the ABS chiller-heater system was reduced by 30% compared to existing operation and the total energy consumption of heat source equipment was reduced by 78%.

  6. Electrically heated particulate filter regeneration methods and systems for hybrid vehicles

    Science.gov (United States)

    Gonze, Eugene V.; Paratore, Jr., Michael J.

    2010-10-12

    A control system for controlling regeneration of a particulate filter for a hybrid vehicle is provided. The system generally includes a regeneration module that controls current to the particulate filter to initiate regeneration. An engine control module controls operation of an engine of the hybrid vehicle based on the control of the current to the particulate filter.

  7. Diagnostic accuracy of 128-slice dual-source CT coronary angiography: a randomized comparison of different acquisition protocols

    International Nuclear Information System (INIS)

    Neefjes, Lisan A.; Kate, Gert-Jan R. ten; Rossi, Alexia; Nieman, Koen; Papadopoulou, Stella L.; Dharampal, Anoeshka S.; Dedic, Admir; Feyter, Pim J. de; Mollet, Nico R.; Genders, Tessa S.S.; Hunink, M.G.M.; Schultz, Carl J.; Weustink, Annick C.; Dijkshoorn, Marcel L.; Straten, Marcel van; Cademartiri, Filippo; Krestin, Gabriel P.

    2013-01-01

    To compare the diagnostic performance and radiation exposure of 128-slice dual-source CT coronary angiography (CTCA) protocols to detect coronary stenosis with more than 50 % lumen obstruction. We prospectively included 459 symptomatic patients referred for CTCA. Patients were randomized between high-pitch spiral vs. narrow-window sequential CTCA protocols (heart rate below 65 bpm, group A), or between wide-window sequential vs. retrospective spiral protocols (heart rate above 65 bpm, group B). Diagnostic performance of CTCA was compared with quantitative coronary angiography in 267 patients. In group A (231 patients, 146 men, mean heart rate 58 ± 7 bpm), high-pitch spiral CTCA yielded a lower per-segment sensitivity compared to sequential CTCA (89 % vs. 97 %, P = 0.01). Specificity, PPV and NPV were comparable (95 %, 62 %, 99 % vs. 96 %, 73 %, 100 %, P > 0.05) but radiation dose was lower (1.16 ± 0.60 vs. 3.82 ± 1.65 mSv, P 0.05). Radiation dose of sequential CTCA was lower compared to retrospective CTCA (6.12 ± 2.58 vs. 8.13 ± 4.52 mSv, P < 0.001). Diagnostic performance was comparable in both groups. Sequential CTCA should be used in patients with regular heart rates using 128-slice dual-source CT, providing optimal diagnostic accuracy with as low as reasonably achievable (ALARA) radiation dose. circle 128-slice dual-source CT coronary angiography offers several different acquisition protocols. (orig.)

  8. Technical Note: Insertion of digital lesions in the projection domain for dual-source, dual-energy CT.

    Science.gov (United States)

    Ferrero, Andrea; Chen, Baiyu; Li, Zhoubo; Yu, Lifeng; McCollough, Cynthia

    2017-05-01

    To compare algorithms performing material decomposition and classification in dual-energy CT, it is desirable to know the ground truth of the lesion to be analyzed in real patient data. In this work, we developed and validated a framework to insert digital lesions of arbitrary chemical composition into patient projection data acquired on a dual-source, dual-energy CT system. A model that takes into account beam-hardening effects was developed to predict the CT number of objects with known chemical composition. The model utilizes information about the x-ray energy spectra, the patient/phantom attenuation, and the x-ray detector energy response. The beam-hardening model was validated on samples of iodine (I) and calcium (Ca) for a second-generation dual-source, dual-energy CT scanner for all tube potentials available and a wide range of patient sizes. The seven most prevalent mineral components of renal stones were modeled and digital stones were created with CT numbers computed for each patient/phantom size and x-ray energy spectra using the developed beam-hardening model. Each digital stone was inserted in the dual-energy projection data of a water phantom scanned on a dual-source scanner and reconstructed with the routine algorithms in use in our practice. The geometry of the forward projection for dual-energy data was validated by comparing CT number accuracy and high-contrast resolution of simulated dual-energy CT data of the ACR phantom with experimentally acquired data. The beam-hardening model and forward projection method accurately predicted the CT number of I and Ca over a wide range of tube potentials and phantom sizes. The images reconstructed after the insertion of digital kidney stones were consistent with the images reconstructed from the scanner, and the CT number ratios for different kidney stone types were consistent with data in the literature. A sample application of the proposed tool was also demonstrated. A framework was developed and validated

  9. Performance of U.S. hybrid distributed energy systems: Solar photovoltaic, battery and combined heat and power

    International Nuclear Information System (INIS)

    Shah, Kunal K.; Mundada, Aishwarya S.; Pearce, J.M.

    2015-01-01

    Highlights: • Simulated PV + battery + CHP hybrid systems deployed in three U.S. regions. • Used hybrid optimization model for electric renewable pro microgrid analysis. • Limited size of each sub-module to singe family house size. • Results show that the electricity generated meets residential load demand. • Hybrid systems are technically viable in hot, moderate and cold climates in U.S. - Abstract: Until recently, the relatively high levelized cost of electricity from solar photovoltaic (PV) technology limited deployment; however, recent cost reductions, combined with various financial incentives and innovative financing techniques, have made PV fully competitive with conventional sources in many American regions. In addition, the costs of electrical storage have also declined enough to make PV + battery systems potentially economically viable for a mass-scale off-grid low-emission transition. However, many regions in the U.S. (e.g. Northern areas) cannot have off-grid PV systems without prohibitively large battery systems. Small-scale combined heat and power (CHP) systems provide a potential solution for off-grid power backup of residential-scale PV + battery arrays, while also minimizing emissions from conventional sources. Thus, an opportunity is now available to maximize the use of solar energy and gain the improved efficiencies possible with CHPs to deploy PV + battery + CHP systems throughout the U.S. The aim of this study is to determine the technical viability of such systems by simulating PV + battery + CHP hybrid systems deployed in three representative regions in the U.S., using the Hybrid Optimization Model for Electric Renewable (HOMER) Pro Microgrid Analysis tool. The results show that the electricity generated by each component of the hybrid system can be coupled to fulfill the residential load demand. A sensitivity analysis of these hybrid off grid systems is carried out as a function capacity factor of both the PV and CHP units. The

  10. Feasibility study on novel hybrid ground coupled heat pump system with nocturnal cooling radiator for cooling load dominated buildings

    International Nuclear Information System (INIS)

    Man, Yi; Yang, Hongxing; Spitler, Jeffrey D.; Fang, Zhaohong

    2011-01-01

    Highlights: → Propose a novel HGCHP system with NCR works as supplemental heat rejecter. → Establish the analytical model and computer program of NCR and novel HGCHP system to simulate their operation performance. → Design the novel HGCHP system for a sample building located in Hong Kong. → It is found to be feasible to use NCR serves as supplemental heat rejecter of the novel HGCHP system. → The novel HGCHP system provides a new valuable choice for air conditioning in cooling load dominated buildings. -- Abstract: When the ground coupled heat pump (GCHP) system is utilized for air conditioning in cooling load dominated buildings, the heat rejected into ground will accumulate around the ground heat exchangers (GHE) and results in system performance degradation. A novel hybrid ground coupled heat pump (HGCHP) system with nocturnal cooling radiator (NCR) works as supplemental heat rejecter is proposed in this paper to resolve this problem. The practical analytical model of NCR and novel HGCHP system are established. The computer program based on established model is developed to simulate the system operation performance. The novel HGCHP system is designed and simulated for a sample building located in Hong Kong, and a simple life cycle cost comparisons are carried out between this system and conventional GCHP system. The results indicate that it is feasible to use NCR serves as supplemental heat rejecter of the novel HGCHP system for cooling load dominated buildings even those located in humid subtropical climate areas. This novel HGCHP system provides a new valuable choice for air conditioning in cooling load dominated buildings, and it is especially suitable for buildings with limited surface land areas.

  11. Optimization for steady-state and hybrid operations of ITER by using scaling models of divertor heat load

    International Nuclear Information System (INIS)

    Murakami, Yoshiki; Itami, Kiyoshi; Sugihara, Masayoshi; Fujieda, Hirobumi.

    1992-09-01

    Steady-state and hybrid mode operations of ITER are investigated by 0-D power balance calculations assuming no radiation and charge-exchange cooling in divertor region. Operation points are optimized with respect to divertor heat load which must be reduced to the level of ignition mode (∼5 MW/m 2 ). Dependence of the divertor heat load on the variety of the models, i.e., constant-χ model, Bohm-type-χ model and JT-60U empirical scaling model, is also discussed. The divertor heat load increases linearly with the fusion power (P FUS ) in all models. The possible highest fusion power much differs for each model with an allowable divertor heat load. The heat load evaluated by constant-χ model is, for example, about 1.8 times larger than that by Bohm-type-χ model at P FUS = 750 MW. Effect of reduction of the helium accumulation, improvements of the confinement capability and the current-drive efficiency are also investigated aiming at lowering the divertor heat load. It is found that NBI power should be larger than about 60 MW to obtain a burn time longer than 2000 s. The optimized operation point, where the minimum divertor heat load is achieved, does not depend on the model and is the point with the minimum-P FUS and the maximum-P NBI . When P FUS = 690 MW and P NBI = 110 MW, the divertor heat load can be reduced to the level of ignition mode without impurity seeding if H = 2.2 is achieved. Controllability of the current-profile is also discussed. (J.P.N.)

  12. A novel syngas-fired hybrid heating source for solar-thermal applications: Energy and exergy analysis

    International Nuclear Information System (INIS)

    Pramanik, Santanu; Ravikrishna, R.V.

    2016-01-01

    Highlights: • Biomass-derived syngas as a hybrid energy source for solar thermal power plants. • A novel combustor concept using rich-catalytic and MILD combustion technologies. • Hybrid energy source for a solar-driven supercritical CO 2 -based Brayton cycle. • Comprehensive energetic and exergetic analysis of the combined system. - Abstract: A hybrid heating source using biomass-derived syngas is proposed to enable continuous operation of standalone solar thermal power generation plants. A novel, two-stage, low temperature combustion system is proposed that has the potential to provide stable combustion of syngas with near-zero NO x emissions. The hybrid heating system consists of a downdraft gasifier, a two-stage combustion system, and other auxiliaries. When integrated with a solar cycle, the entire system can be referred to as the integrated gasification solar combined cycle (IGSCC). The supercritical CO 2 Brayton cycle (SCO 2 ) is selected for the solar cycle due to its high efficiency. The thermodynamic performance evaluation of the individual unit and the combined system has been conducted from both energy and exergy considerations. The effect of parameters such as gasification temperature, biomass moisture content, equivalence ratio, and pressure ratio is studied. The efficiency of the IGSCC exhibited a non-monotonic behavior. A maximum thermal efficiency of 36.5% was achieved at an overall equivalence ratio of 0.22 and pressure ratio of 2.75 when the gasifier was operating at T g = 1073 K with biomass containing 20% moisture. The efficiency increased to 40.8% when dry biomass was gasified at a temperature of 973 K. The exergy analysis revealed that the maximum exergy destruction occurred in the gasification system, followed by the combustion system, SCO 2 cycle, and regenerator. The exergy analysis also showed that 8.72% of the total exergy is lost in the exhaust; however, this can be utilized for drying of the biomass.

  13. Numerical study of the enhancement of heat transfer for hybrid CuO-Cu Nanofluids flowing in a circular pipe.

    Science.gov (United States)

    Balla, Hyder H; Abdullah, Shahrir; Mohdfaizal, Wan; Zulkifli, Rozli; Sopian, Kamaruzaman

    2013-01-01

    A numerical simulation model for laminar flow of nanofluids in a pipe with constant heat flux on the wall was built to study the effect of the Reynolds number on convective heat transfer and pressure loss. The investigation was performed for hybrid nanofluids consisting of CuO-Cu nanoparticles and compared with CuO and Cu in which the nanoparticles have a spherical shape with size 50, 50, 50nm respectively. The nanofluids were prepared, following which the thermal conductivity and dynamic viscosity were measured for a range of temperatures (10 -60°C). The numerical results obtained were compared with the existing well-established correlation. The prediction of the Nusselt number for nanofluids agrees well with the Shah correlation. The comparison of heat transfer coefficients for CuO, Cu and CuO-Cu presented an increase in thermal conductivity of the nanofluid as the convective heat transfer coefficient increased. It was found that the pressure loss increases with an increase in the Reynolds number, nanoparticle density and particle volume fraction. However, the flow demonstrates enhancement in heat transfer which becomes greater with an increase in the Reynolds number for the nanofluid flow.

  14. Hybrid Cooling Loop Technology for Robust High Heat Flux Cooling, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced Cooling Technologies, Inc. (ACT) proposes to develop a hybrid cooling loop and cold plate technology for space systems thermal management. The proposed...

  15. Dual source multidetector CT-angiography before transcatheter aortic valve implantation (TAVI) using a high-pitch spiral acquisition mode

    Energy Technology Data Exchange (ETDEWEB)

    Wuest, W.; Anders, K.; May, M.S.; Uder, M. [University of Erlangen, Department of Radiology, Erlangen (Germany); Schuhbaeck, A.; Gauss, S.; Marwan, M.; Arnold, M.; Muschiol, G.; Daniel, W.G.; Achenbach, S. [University of Erlangen, Department of Cardiology, Erlangen (Germany); Ensminger, S. [University of Erlangen, Department of Cardiac Surgery, Erlangen (Germany)

    2012-01-15

    Transcatheter Aortic Valve Implantation (TAVI) is an alternative to surgical valve replacement in high risk patients. Angiography of the aortic root, aorta and iliac arteries is required to select suitable candidates, but contrast agents can be harmful due to impaired renal function. We evaluated ECG-triggered high-pitch spiral dual source Computed Tomography (CT) with minimized volume of contrast agent to assess aortic root anatomy and vascular access. 42 patients (82 {+-} 6 years) scheduled for TAVI underwent dual source (DS) CT angiography (CTA) of the aorta using a prospectively ECG-triggered high-pitch spiral mode (pitch = 3.4) with 40 mL iodinated contrast agent. We analyzed aortic root/iliac dimensions, attenuation, contrast to noise ratio (CNR), image noise and radiation exposure. Aortic root/iliac dimensions and distance of coronary ostia from the annulus could be determined in all cases. Mean aortic and iliac artery attenuation was 320 {+-} 70 HU and 340 {+-} 77 HU. Aortic/iliac CNR was 21.7 {+-} 6.8 HU and 14.5 {+-} 5.4 HU using 100 kV (18.8 {+-} 4.1 HU and 8.7 {+-} 2.6 HU using 120 kV). Mean effective dose was 4.5 {+-} 1.2 mSv. High-pitch spiral DSCTA can be used to assess the entire aorta and iliac arteries in TAVI candidates with a low volume of contrast agent while preserving diagnostic image quality. (orig.)

  16. Comparison of carotid and cerebrovascular disease between diabetic and non-diabetic patients using dual-source CT

    International Nuclear Information System (INIS)

    He Ci; Yang Zhigang; Chu Zhigang; Dong Zhihui; Li Yunming; Shao Heng; Deng Wen

    2011-01-01

    Purpose: To clarify the differences of the carotid and cerebrovascular disease between patients with and without type 2 diabetes using dual-source CT angiography. Materials and methods: Dual-source CT angiography of the carotid and cerebrovascular arteries was performed in 79 type 2 diabetic patients and 207 non-diabetic patients. The type, extent and distribution of plaques, and luminal stenosis were compared. Results: Compared with non-diabetic patients, diabetic patients had a higher overall incidence of plaque (p 0.05), as well as for the number of diseased segments and the distribution of plaques; both mainly involved the bilateral cavernous segment of the internal carotid artery. As for the stenosis, non-obstructive lesions were more common in diabetic patients (p 0.05). Conclusion: Diabetes is associated with a higher incidence of plaque and non-obstructive stenosis. However, no significant differences were observed in the type, extent and distribution of involved plaques between diabetic and non-diabetic patients.

  17. Estimation of the radiation exposure of a chest pain protocol with ECG-gating in dual-source computed tomography

    International Nuclear Information System (INIS)

    Ketelsen, Dominik; Luetkhoff, Marie H.; Thomas, Christoph; Werner, Matthias; Tsiflikas, Ilias; Reimann, Anja; Kopp, Andreas F.; Claussen, Claus D.; Heuschmid, Martin; Buchgeister, Markus; Burgstahler, Christof

    2009-01-01

    The aim of the study was to evaluate radiation exposure of a chest pain protocol with ECG-gated dual-source computed tomography (DSCT). An Alderson Rando phantom equipped with thermoluminescent dosimeters was used for dose measurements. Exposure was performed on a dual-source computed tomography system with a standard protocol for chest pain evaluation (120 kV, 320 mAs/rot) with different simulated heart rates (HRs). The dose of a standard chest CT examination (120 kV, 160 mAs) was also measured. Effective dose of the chest pain protocol was 19.3/21.9 mSv (male/female, HR 60), 17.9/20.4 mSv (male/female, HR 80) and 14.7/16.7 mSv (male/female, HR 100). Effective dose of a standard chest examination was 6.3 mSv (males) and 7.2 mSv (females). Radiation dose of the chest pain protocol increases significantly with a lower heart rate for both males (p = 0.040) and females (p = 0.044). The average radiation dose of a standard chest CT examination is about 36.5% that of a CT examination performed for chest pain. Using DSCT, the evaluated chest pain protocol revealed a higher radiation exposure compared with standard chest CT. Furthermore, HRs markedly influenced the dose exposure when using the ECG-gated chest pain protocol. (orig.)

  18. A comparative study of electrocardiogram multi-segment reconstruction and dual source computed tomography using a computer controlled coronary phantom

    International Nuclear Information System (INIS)

    Ohashi, Kazuya; Higashide, Ryo; Kunitomo, Hirosi; Ichikawa, Katsuhiro

    2011-01-01

    Currently, there are two main methods for improving temporal resolution of coronary computed tomography (CT): electrocardiogram-gated multi-segment reconstruction (EMR) and dual source scanning using dual source CT (DSCT). We developed a motion phantom system for image quality assessment of cardiac CT to evaluate these two methods. This phantom system was designed to move an object at arbitrary speeds during a desired phase range in cyclic motion. By using this system, we obtained coronary CT mode images for motion objects like coronary arteries. We investigated the difference in motion artifacts between EMR and the DSCT using a 3-mm-diameter acrylic rod resembling the coronary artery. EMR was evaluated using 16-row multi-slice CT (16MSCT). To evaluate the image quality, we examined the degree of motion artifacts by analyzing the profiles around the rod and the displacement of a peak pixel in the rod image. In the 16MSCT, remarkable increases of artifacts and displacement were caused by the EMR. In contrast, the DSCT presented excellent images with fewer artifacts. The results showed the validity of DSCT to improve true temporal resolution. (author)

  19. Experimental Results and Model Calculations of a Hybrid Adsorption-Compression Heat Pump Based on a Roots Compressor and Silica Gel-Water Sorption

    Energy Technology Data Exchange (ETDEWEB)

    Van der Pal, M.; De Boer, R.; Wemmers, A.K.; Smeding, S.F.; Veldhuis, J.B.J.; Lycklama a Nijeholt, J.A.

    2013-10-15

    Thermally driven sorption systems can provide significant energy savings, especially in industrial applications. The driving temperature for operation of such systems limits the operating window and can be a barrier for market-introduction. By adding a compressor, the sorption cycle can be run using lower waste heat temperatures. ECN has recently started the development of such a hybrid heat pump. The final goal is to develop a hybrid heat pump for upgrading lower (<100C) temperature industrial waste heat to above pinch temperatures. The paper presents the first measurements and model calculations of a hybrid heat pump system using a water-silica gel system combined with a Roots type compressor. From the measurements can be seen that the effect of the compressor is dependent on where in the cycle it is placed. When placed between the evaporator and the sorption reactor, it has a considerable larger effect compared to the compressor placed between the sorption reactor and the condenser. The latter hardly improves the performance compared to purely heat-driven operation. This shows the importance of studying the interaction between all components of the system. The model, which shows reasonable correlation with the measurements, could proof to be a valuable tool to determine the optimal hybrid heat pump configuration.

  20. [Effects of exogenous silicon on the pollination and fertility characteristics of hybrid rice under heat stress during anthesis].

    Science.gov (United States)

    Wu, Chen-Yang; Chen, Dan; Luo, Hai-Wei; Yao, Yi-min; Wang, Zhi-Wei; Tsutomu, Matsui; Tian, Xiao-Hai

    2013-11-01

    Taking two medium-maturing indica rice hybrids Jinyou 63 and Shanyou 63 as test materials, this paper studied the effects of applying silicon fertilizer on the flag leaf chlorophyll content, photosynthetic properties, antioxidant enzyme activities, malondialdehyde (MDA) content, pollen vigor, anther acid invertase activity, pollination, and seed-setting of hybrid rice under the heat stress during anthesis. This study was conducted in pots and under growth chamber. Soluble solution of silicon fertilizer applied as Na2SiO3 x 9H2O was sprayed on the growing plants after early jointing stage, with three times successively and at an interval of one week. The pots were then moved into growth chamber to subject to normal temperature vs. high temperature (termed as heat stress) for five days. In treatment normal temperature, the average daily temperature was set at 26.6 degrees C, and the maximum daily temperature was set at 29.4 degres C; in treatment high temperature, the average and the maximum daily temperature were set at 33.2 degrees C and 40.1 degrees C, respectively. As compared with the control, applying silicon increased the flag leaf chlorophyll content significantly, improved the net photosynthetic rate and stomatal conductance, decreased the accumulative inter- cellular CO2 concentration, improved the leaf photosynthesis, reduced the MDA content, and improved the activities of SOD, POD and CAT under heat stress. In addition, applying silicon improved the anther acid invertase activity and the pollen vigor, increased the anther basal dehiscence width, total number of pollination per stigma, germinated number, germination rate of pollen, and percentage of florets with more than 10 germinated pollen grains, decreased the percentage of florets with fewer than 20 germinated pollen grains, and thus, alleviated the fertility loss of Jinyou 63 and Shanyou 63 under heat stress by 13.4% and 14.1%, respectively. It was suggested that spraying exogenous silicon in the

  1. Development of Hybrid Kiln Drying System with Radio Frequency Heating for the Sugi Heart Timber

    OpenAIRE

    Piao, Jinji; Fujimoto, Noboru; Yamamoto, Yasushi; Nagata, Soji

    2007-01-01

    In this study, proper applied stage of the radio-frequency (RF) heating during kiln drying based on the quality concerning the surface checks of the boxed heart timbers was examined. At the stage of the RF heating the moisture contents decreased clearly at the internal parts of timbers. The surface stress of the sugi (Cryptomeria japonica D. Don) boxed heart timber changed into the compression stress by the RF heating in any drying stage. The surface checks increased according to the decrease...

  2. Low-dose computed tomography of the paranasal sinus and facial skull using a high-pitch dual-source system - First clinical results

    International Nuclear Information System (INIS)

    Schell, Boris; Bauer, Ralf W.; Lehnert, Thomas; Kerl, J.M.; Vogl, Thomas J.; Mack, Martin G.; Hambek, Markus; May, Angelika

    2011-01-01

    Computed tomography (CT) of the paranasal sinus is the standard diagnostic tool for a wide range of indications in mostly younger patients. This study aims to assess the image quality of CT of the sinus by using a high-pitch dual-source technique with special regard to the radiation dose. Examinations were performed on a second-generation dual-source CT with a pitch factor of 3.0 (dual-source mode). Images were compared with those with a pitch factor of 0.9 on the same system (single-source mode) and with those of 16-slice CT. Image quality was evaluated by four blinded readers using a 5-point scale (1 = poor, 5 = excellent). Comparison of the dose length product (DLP) was used to estimate radiation exposure. Seventy-three consecutive patients underwent imaging with the proposed CT protocols. The viewers rated the image quality of the dual-source image sets as nearly as good (3.62) as the single-source images on the same device (4.18) and those on 16-slice CT (3.7). DLP was cut to half of the dose [51 mGycm vs. 97.8 mGycm vs. 116.9 mGycm (p < 0.01)]. Using the proposed dual-source mode when examining the paranasal sinus, diagnostic image quality can be achieved while drastically lowering the patient's radiation exposure. (orig.)

  3. Influence of heat treatment on hole transfer dynamics in core-shell quantum dot/organic hole conductor hybrid films

    Science.gov (United States)

    Sun, Mingye; Zheng, Youjin; Zhang, Lei; Zhao, Liping; Zhang, Bing

    2017-08-01

    The influence of heat treatment on hole transfer (HT) processes from the CdSe/ZnS and CdSe/CdS/ZnS quantum dots (QDs) to 4,4‧,4″-Tris(carbazol-9-yl)-triphenylamine (TCTA) in QD/TCTA hybrid films has been researched with time-resolved photoluminescence (PL) spectroscopy. The PL dynamic results demonstrated a heat-treatment-temperature-dependent HT process from the core-shell CdSe QDs to TCTA. The HT rates and efficiencies can be effectively increased due to reduced distance between core-shell CdSe QDs and TCTA after heat treatment. The CdS shell exhibited a more obvious effect on HT from the core-shell CdSe QDs to TCTA than on electron transfer to TiO2, due to higher barrier for holes to tunnel through CdS shell and larger effective mass of holes in CdS than electrons. These results indicate that heat treatment would be an effective means to further optimize solid-state QD sensitized solar cells and rational design of CdS shell is significant.

  4. Particle simulation on the propagation and plasma heating of the lower hybrid wave in the nonuniform system

    International Nuclear Information System (INIS)

    Abe, Hirotada; Kajitani, Hiroyuki; Itatani, Ryohei.

    1977-07-01

    A particle simulation model which treats the wave excitation and propagation in the nonuniform density by the external source is developed and applied for study of the lower hybrid heating in a fusion device. As the linear theory predicts, the cold lower hybrid wave is observed to increase its perpendicular wave number as it propagates to the higher density region and to damp away near the turning point. When the wave amplitude is large or the wave energy is about a half of the initial kinetic energy at a surface of plasma, the following features are observed for the increase of the ion and electron kinetic energies. Ion perpendicular energy distributions are observed to be approximated by the two Maxwell distributions or to have the components of the high energy tail, whose parallel velocities satisfy the resonance condition: νparallel = (ω-IOTAΩ sub(iota))/kappa parallel, where ω and kappa parallel the frequency and the parallel wave number of the external source, IOTA is an integer, and Ω sub(iota) is the ion cyclotron frequency. An strong increase of the parallel kinetic energy of the electron is observed near the plasma surface. These are mainly due to the trapped electrons and the collisional heating. (auth.)

  5. OligoHeatMap (OHM): an online tool to estimate and display hybridizations of oligonucleotides onto DNA sequences.

    Science.gov (United States)

    Croce, Olivier; Chevenet, François; Christen, Richard

    2008-07-01

    The efficiency of molecular methods involving DNA/DNA hybridizations depends on the accurate prediction of the melting temperature (T(m)) of the duplex. Many softwares are available for T(m) calculations, but difficulties arise when one wishes to check if a given oligomer (PCR primer or probe) hybridizes well or not on more than a single sequence. Moreover, the presence of mismatches within the duplex is not sufficient to estimate specificity as it does not always significantly decrease the T(m). OHM (OligoHeatMap) is an online tool able to provide estimates of T(m) for a set of oligomers and a set of aligned sequences, not only as text files of complete results but also in a graphical way: T(m) values are translated into colors and displayed as a heat map image, either stand alone or to be used by softwares such as TreeDyn to be included in a phylogenetic tree. OHM is freely available at http://bioinfo.unice.fr/ohm/, with links to the full source code and online help.

  6. Optimization of ground source heat pumps systems through the implementation of hybrid systems; Optimizacion de las instalaciones de bomba de calor geotermica mediante la implementacion de sistemas hibridos

    Energy Technology Data Exchange (ETDEWEB)

    Magraner, T.; Quilis, M. S.; Martinez, S.

    2009-07-01

    One of the fundamental aspects to consider in the design of a ground heat pump system is the heat balance in the ground since thermal saturation of the ground produces a decreasing of the performance of the system throughout its useful life. The hybrid geothermal system which combined geothermal heat pump system with other systems for generation or dissipation energy are very suitable for balancing the heat exchanger meters needed for the proper functioning of the system, important aspect to reduce costs and achieve attractive return periods of the initial investment. Energesis Ingenieria has developed and implemented in two office buildings, a design of hybrid systems based on the combination of a geothermal heat pump and air-condensed units (dry coolers) that can ensure energy efficiencies comparable to geothermal pure systems, reducing substantially the investment cost. (Author) 5 refs.

  7. Annual measured and simulated thermal performance analysis of a hybrid solar district heating plant with flat plate collectors and parabolic trough collectors in series

    DEFF Research Database (Denmark)

    Tian, Zhiyong; Perers, Bengt; Furbo, Simon

    2017-01-01

    Flat plate collectors have relatively low efficiency at the typical supply temperatures of district heating networks (70–95 °C). Parabolic trough collectors retain their high efficiency at these temperatures. To maximize the advantages of flat plate collectors and parabolic trough collectors in l...... for this type of hybrid solar district heating plants with flat plate collectors and parabolic trough collectors in the Nordic region, but also introduce a novel design concept of solar district heating plants to other high solar radiation areas....... in large solar heating plants for a district heating network, a hybrid solar collector field with 5960 m2 flat plate collectors and 4039 m2 parabolic trough collectors in series was constructed in Taars, Denmark. The design principle is that the flat plate collectors preheat the return water from...

  8. Effectiveness of Using Dual-source CT and the Upshot it creates on Both Heart Rate and Image Quality

    Directory of Open Access Journals (Sweden)

    Tuba Selçuk

    2016-06-01

    Full Text Available Background: Early detection of coronary artery disease (CAD is important because of the high morbidity and mortality rates. As invasive coronary angiography (ICA is an invasive procedure, an alternative diagnostic method; coronary computed tomography angiography (CTA, has become more widely used by the improvements in detector technology. Aims: In this study, we aimed to examine the accuracy and image quality of high-pitch 128-slice dual-source CTA taking the ICA as reference technique. We also aimed to compare the accuracy and image quality between different heart rate groups of >70 beates per minute (bpm and ≤70 bpm. Study Design: Retrospective cross-sectional study. Methods: Among 450 patients who underwent coronary CTA with the FLASH spiral technique, performed with a second generation dual-source computed tomography device with a pitch value of 3.2, 102 patients without stent and/or bypass surgery history and clinically suspected coronary artery disease who underwent ICA within 15 days were enrolled. Image quality was assessed by two independent radiologists using a 4-point scale (1=absence of any artifacts- 4=non-evaluable. A stenosis >50% was considered significant on a per-segment, per-vessel, and per-patient basis and ICA was considered the reference method. Radiation doses were determined using dose length product (DLP values detected by the computed tomography (CT device. In addition, patients were classified into two groups according to their heart rates as ≤70 bpm (73 patients and >70 bpm (29 patients. The relation between the diagnostic accuracy and heart rate groups were evaluated. Results: Overall, 1495 (98% coronary segments were diagnostic in 102 patients (32 male, 70 female, mean heart rate: 65 bpm. There was a significant correlation between image quality and mean heart rate in the right coronary artery (RCA segments. The effective radiation dose was 0.98±0.09 mili Sievert (mSv. On a per-patient basis, sensitivity

  9. Radiation dose levels in pediatric chest CT: experience in 499 children evaluated with dual-source single-energy CT

    Energy Technology Data Exchange (ETDEWEB)

    Martine, Remy-Jardin; Colas, Lucie; Jean-Baptiste, Faivre; Remy, Jacques [CHU Lille (EA 2694) University of Lille, Department of Thoracic Imaging, Hospital Calmette, Lille (France); Santangelo, Teresa [CHU Lille (EA 2694) University of Lille, Department of Thoracic Imaging, Hospital Calmette, Lille (France); Bambino Gesu Children' s Hospital, Department of Imaging, Rome (Italy); Duhamel, Alain [University of Lille (EA 2694), Department of Biostatistics, CHU Lille, Lille (France); Deschildre, Antoine [CHU Lille - University of Lille, Department of Pediatric Pulmonology, Lille (France)

    2017-02-15

    The availability of dual-source technology has introduced the possibility of scanning children at lower kVp with a high-pitch mode, combining high-speed data acquisition and high temporal resolution. To establish the radiation dose levels of dual-source, single-energy chest CT examinations in children. We retrospectively recorded the dose-length product (DLP) of 499 consecutive examinations obtained in children <50 kg, divided into five weight groups: group 1 (<10 kg, n = 129); group 2 (10-20 kg, n = 176); group 3 (20-30 kg, n = 99), group 4 (30-40 kg, n = 58) and group 5 (40-49 kg, n = 37). All CT examinations were performed with high temporal resolution (75 ms), a high-pitch mode and a weight-adapted selection of the milliamperage. CT examinations were obtained at 80 kVp with a milliamperage ranging between 40 mAs and 90 mAs, and a pitch of 2.0 (n = 162; 32.5%) or 3.0 (n = 337; 67.5%). The mean duration of data acquisition was 522.8 ± 192.0 ms (interquartile range 390 to 610; median 490). In the study population, the mean CT dose index volume (CTDIvol{sub 32}) was 0.83 mGy (standard deviation [SD] 0.20 mGy; interquartile range 0.72 to 0.94; median 0.78); the mean DLP{sub 32} was 21.4 mGy.cm (SD 9.1 mGy.cm; interquartile range 15 to 25; median 19.0); and the mean size-specific dose estimate (SSDE) was 1.7 mGy (SD 0.4 mGy; interquartile range 1.5 to 1.9; median 1.7). The DLP{sub 32}, CTDI{sub vol32} and SSDE were found to be statistically significant in the five weight categories (P < 0.0001). This study establishes the radiation dose levels for dual-source, single-kVp chest CT from a single center. In the five weight categories, the median values varied 15-37 mGy.cm for the DLP{sub 32}, 0.78-1.25 mGy for the CTDI{sub vol32} and 1.6-2.1 mGy for the SSDE. (orig.)

  10. Radiation dose levels in pediatric chest CT: experience in 499 children evaluated with dual-source single-energy CT

    International Nuclear Information System (INIS)

    Martine, Remy-Jardin; Colas, Lucie; Jean-Baptiste, Faivre; Remy, Jacques; Santangelo, Teresa; Duhamel, Alain; Deschildre, Antoine

    2017-01-01

    The availability of dual-source technology has introduced the possibility of scanning children at lower kVp with a high-pitch mode, combining high-speed data acquisition and high temporal resolution. To establish the radiation dose levels of dual-source, single-energy chest CT examinations in children. We retrospectively recorded the dose-length product (DLP) of 499 consecutive examinations obtained in children <50 kg, divided into five weight groups: group 1 (<10 kg, n = 129); group 2 (10-20 kg, n = 176); group 3 (20-30 kg, n = 99), group 4 (30-40 kg, n = 58) and group 5 (40-49 kg, n = 37). All CT examinations were performed with high temporal resolution (75 ms), a high-pitch mode and a weight-adapted selection of the milliamperage. CT examinations were obtained at 80 kVp with a milliamperage ranging between 40 mAs and 90 mAs, and a pitch of 2.0 (n = 162; 32.5%) or 3.0 (n = 337; 67.5%). The mean duration of data acquisition was 522.8 ± 192.0 ms (interquartile range 390 to 610; median 490). In the study population, the mean CT dose index volume (CTDIvol 32 ) was 0.83 mGy (standard deviation [SD] 0.20 mGy; interquartile range 0.72 to 0.94; median 0.78); the mean DLP 32 was 21.4 mGy.cm (SD 9.1 mGy.cm; interquartile range 15 to 25; median 19.0); and the mean size-specific dose estimate (SSDE) was 1.7 mGy (SD 0.4 mGy; interquartile range 1.5 to 1.9; median 1.7). The DLP 32 , CTDI vol32 and SSDE were found to be statistically significant in the five weight categories (P < 0.0001). This study establishes the radiation dose levels for dual-source, single-kVp chest CT from a single center. In the five weight categories, the median values varied 15-37 mGy.cm for the DLP 32 , 0.78-1.25 mGy for the CTDI vol32 and 1.6-2.1 mGy for the SSDE. (orig.)

  11. Design sensitivity analysis for heavy-duty hybrid electric trucks with a waste heat recovery system

    NARCIS (Netherlands)

    Verbruggen, F.J.R.; Hofman, T.

    One general trend aiming to improve the development of hybrid electric powertrains is the reduction of production cost of powertrains by developing powertrain components that can be used for multiple vehicle segments. The development of these kind of modular powertrain components requires knowledge

  12. Accuracy of Dual-Energy Virtual Monochromatic CT Numbers: Comparison between the Single-Source Projection-Based and Dual-Source Image-Based Methods.

    Science.gov (United States)

    Ueguchi, Takashi; Ogihara, Ryota; Yamada, Sachiko

    2018-03-21

    To investigate the accuracy of dual-energy virtual monochromatic computed tomography (CT) numbers obtained by two typical hardware and software implementations: the single-source projection-based method and the dual-source image-based method. A phantom with different tissue equivalent inserts was scanned with both single-source and dual-source scanners. A fast kVp-switching feature was used on the single-source scanner, whereas a tin filter was used on the dual-source scanner. Virtual monochromatic CT images of the phantom at energy levels of 60, 100, and 140 keV were obtained by both projection-based (on the single-source scanner) and image-based (on the dual-source scanner) methods. The accuracy of virtual monochromatic CT numbers for all inserts was assessed by comparing measured values to their corresponding true values. Linear regression analysis was performed to evaluate the dependency of measured CT numbers on tissue attenuation, method, and their interaction. Root mean square values of systematic error over all inserts at 60, 100, and 140 keV were approximately 53, 21, and 29 Hounsfield unit (HU) with the single-source projection-based method, and 46, 7, and 6 HU with the dual-source image-based method, respectively. Linear regression analysis revealed that the interaction between the attenuation and the method had a statistically significant effect on the measured CT numbers at 100 and 140 keV. There were attenuation-, method-, and energy level-dependent systematic errors in the measured virtual monochromatic CT numbers. CT number reproducibility was comparable between the two scanners, and CT numbers had better accuracy with the dual-source image-based method at 100 and 140 keV. Copyright © 2018 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

  13. Spatial Distribution of Iron Within the Normal Human Liver Using Dual-Source Dual-Energy CT Imaging.

    Science.gov (United States)

    Abadia, Andres F; Grant, Katharine L; Carey, Kathleen E; Bolch, Wesley E; Morin, Richard L

    2017-11-01

    Explore the potential of dual-source dual-energy (DSDE) computed tomography (CT) to retrospectively analyze the uniformity of iron distribution and establish iron concentration ranges and distribution patterns found in healthy livers. Ten mixtures consisting of an iron nitrate solution and deionized water were prepared in test tubes and scanned using a DSDE 128-slice CT system. Iron images were derived from a 3-material decomposition algorithm (optimized for the quantification of iron). A conversion factor (mg Fe/mL per Hounsfield unit) was calculated from this phantom study as the quotient of known tube concentrations and their corresponding CT values. Retrospective analysis was performed of patients who had undergone DSDE imaging for renal stones. Thirty-seven patients with normal liver function were randomly selected (mean age, 52.5 years). The examinations were processed for iron concentration. Multiple regions of interest were analyzed, and iron concentration (mg Fe/mL) and distribution was reported. The mean conversion factor obtained from the phantom study was 0.15 mg Fe/mL per Hounsfield unit. Whole-liver mean iron concentrations yielded a range of 0.0 to 2.91 mg Fe/mL, with 94.6% (35/37) of the patients exhibiting mean concentrations below 1.0 mg Fe/mL. The most important finding was that iron concentration was not uniform and patients exhibited regionally high concentrations (36/37). These regions of higher concentration were observed to be dominant in the middle-to-upper part of the liver (75%), medially (72.2%), and anteriorly (83.3%). Dual-source dual-energy CT can be used to assess the uniformity of iron distribution in healthy subjects. Applying similar techniques to unhealthy livers, future research may focus on the impact of hepatic iron content and distribution for noninvasive assessment in diseased subjects.

  14. Energy Limits in Second Generation High-pitch Dual Source CT - Comparison in an Upper Abdominal Phantom

    Directory of Open Access Journals (Sweden)

    Martin Beeres

    2015-01-01

    Full Text Available Objectives: The aim of our study was to find out how much energy is applicable in second-generation dual source high-pitch computed tomography (CT in imaging of the abdomen. Materials and Methods: We examined an upper abdominal phantom using a Somatom Definition Flash CT-Scanner (Siemens, Forchheim, Germany. The study protocol consisted of a scan-series at 100 kV and 120 kV. In each scan series we started with a pitch of 3.2 and reduced it in steps of 0.2, until a pitch of 1.6 was reached. The current was adjusted to the maximum the scanner could achieve. Energy values, image noise, image quality, and radiation exposure were evaluated. Results: For a pitch of 3.2 the maximum applicable current was 142 mAs at 120 kV and in 100 kV the maximum applicable current was 114 mAs. For conventional abdominal imaging, current levels of 200 to 260 mAs are generally used. To achieve similar current levels, we had to decrease the pitch to 1.8 at 100 kV - at this pitch we could perform our imaging at 204 mAs. At a pitch of 2.2 in 120 kV we could apply a current of 206 mAs. Conclusion: We conclude our study by stating that if there is a need for a higher current, we have to reduce the pitch. In a high-pitch dual source CT, we always have to remember where our main focus is, so we can adjust the pitch to the energy we need in the area of the body that has to be imaged, to find answers to the clinical question being raised.

  15. Virtual unenhanced second generation dual-source CT of the liver: Is it time to discard the conventional unenhanced phase?

    International Nuclear Information System (INIS)

    Barrett, T.; Bowden, D.J.; Shaida, N.; Godfrey, E.M.; Taylor, A.; Lomas, D.J.; Shaw, A.S.

    2012-01-01

    Introduction: Dual-energy dual source CT can almost simultaneously image patients using two different tube potentials, allowing material decomposition and creation of ‘virtual unenhanced’ (VU) images from post-contrast series. Methods: 75 patients undergoing triple-phase liver CT examinations were imaged using a second generation dual-source CT machine with tube potentials 140/100 kVp. Post-processing VU series were derived from arterial and portal phases. Regions-of-interest from liver parenchyma and within fat (‘noise’ assessment) were drawn to compare VU series to conventional unenhanced (CU) series. Subjective analysis assessed image quality and the suitability of VU to replace CU series. Results: Mean Hounsfield unit (HU) values of liver were higher in the VU series: portal 51.9 (SD = 10.29), arterial 51.1 (SD = 10.05), compared to the CU series 49.2 (SD = 9.11); P < 0.001. However, Pearson's correlation of the VU and CU series remained excellent: 0.838 (portal), 0.831 (arterial). Bland–Altman plots also showed good agreement between both VU and the CU datasets. Noise measurements were significantly lower in both VU series (P < 0.001). For subjective analysis, image quality was rated as very good/excellent in 100% of CU images, 93.3% of portal VU and 88.7% of arterial VU series. Overall, portal VU and arterial VU images were acceptable replacements for the CU series in 97.4% and 96.1%, respectively. Post-processing was noted to create a number of artefacts in VU images – knowledge of these is essential for interpretation. Conclusions: Portal and arterial-derived VU images objectively correlate to CU images and demonstrate good image quality and acceptability. VU image sets could replace the conventional unenhanced images in the vast majority of cases, significantly reducing radiation dose.

  16. High Efficiency Water Heating Technology Development Final Report. Part I, Lab/Field Performance Evaluation and Accelerated Life Testing of a Hybrid Electric Heat Pump Water Heater (HPWH)

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, Van D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Murphy, Richard W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Rice, C. Keith [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Linkous, Randall Lee [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-04-01

    DOE has supported efforts for many years with the objective of getting a water heater that uses heat pump technology (aka a heat pump water heater or HPWH) successfully on the residential equipment market. The most recent previous effort (1999-2002) produced a product that performed very well in ORNL-led accelerated durability and field tests. The commercial partner for this effort, Enviromaster International (EMI), introduced the product to the market under the trade name Watter$aver in 2002 but ceased production in 2005 due to low sales. A combination of high sales price and lack of any significant infrastructure for service after the sale were the principal reasons for the failure of this effort. What was needed for market success was a commercial partner with the manufacturing and market distribution capability necessary to allow economies of scale to lead to a viable unit price together with a strong customer service infrastructure. General Electric certainly meets these requirements, and knowing of ORNL s expertise in this area, approached ORNL with the proposal to partner in a CRADA to produce a high efficiency electric water heater. A CRADA with GE was initiated early in Fiscal Year, 2008. GE initially named its product the Hybrid Electric Water Heater (HEWH).

  17. Safety analysis of coupling system of hybrid (MED-RO) nuclear desalination system utilising waste heat from HTGR

    International Nuclear Information System (INIS)

    Raha, Abhijit; Kishore, G.; Rao, I.S.; Adak, A.K.; Srivastava, V.K.; Prabhakar, S.; Tewari, P.K.

    2010-01-01

    To meet the generation IV goals, High Temperature Gas Cooled Reactors (HTGRs) are designed to have relatively higher thermal efficiency and enhanced safety and environmental characteristics. It can provide energy for combined production of hydrogen, electricity and other industrial applications. The waste heat available in the HTGR power cycle can also be utilized for the desalination of seawater for producing potable water. Desalination is an energy intensive process, so use of waste heat from HTGR certainly makes desalination process more affordable to create fresh water resources. So design of the coupling system, as per the safety design requirement of nuclear desalination plant, of desalination plant with HTGR is very crucial. In the first part of this paper, design of the coupling system between hybrid Multi Effect Desalination-Reverse Osmosis (MED-RO) nuclear desalination plant and HTGR to utilize the waste heat in HTGR are discussed. In the next part deterministic safety analysis of the designed coupling system of are presented in detail. It was found that all the coupling system meets the acceptance criteria for all the Postulated Initiating Events (PIE's) limited to DBA. (author)

  18. Thermal Analysis of Hybrid Thermal Control System and Experimental Investigation of Flow Boiling in Micro-channel Heat Exchangers

    Science.gov (United States)

    Lee, Seunghyun

    Future manned space endeavors will require a new class of vehicles, capable of conducting different types of missions and enduring varying gravitational and temperature environments. Thermal management will play a vital role in these new vehicles, and is complicated by the need to tackle both low and high heat sink temperatures. The present study assesses the feasibility of hybrid thermal control system by thermodynamic analysis and investigates the heat transfer mechanisms in two large micro-channel heat exchangers in vapor compression mode and two-phase mode. Unlike prior published two-phase micro-channel studies that concern mostly miniature heat sinks, this study addresses transport characteristics of a heat sink containing large length-to-diameter ratio, up to 609.6 to 1,micro-channels. In the thermodynamic analysis, four different operational modes are considered: single-phase, two-phase, basic heat pump and heat pump with liquid-side, suction-side heat exchanger. A thermodynamic trade study is conducted for six different working fluids to assess important performance parameters including mass flow rate of the working fluid, maximum pressure, radiator area, compressor/pump work, and coefficient of performance (COP). R134a is determined to be most suitable based on its ability to provide a balanced compromise between reducing flow rate and maintaining low system pressure, and a moderate coefficient of performance (COP); this fluid is also both nontoxic and nonflammable, and features zero ozone depletion potential (ODP) and low global warming potential (GWP). It is shown how specific mission stages dictate which mode of operation is most suitable, and this information is used to size the radiator for the H-TCS. The experimental flow boiling investigation consists of exploring the steady-state and the transient two-phase heat transfer characteristics of two large micro-channel heat exchangers that serve as evaporators in the vapor compression loop using R134a as

  19. Heat-Mirror Spectral Profile Optimization for TSC Hybrid Solar Conversion

    Science.gov (United States)

    Soule, D. E.; Wood, S. E.

    1986-09-01

    The efficiencies for total solar cogeneration (TSC) can be optimized by tailoring the transparent heat-mirror (HM) beam splitter spectral profile shape. The entire output is cogenerated by photovoltaic/photothermal conversions into three energy forms: electricity (PV) 18V d.c./module, high-temperature heat (HT) 400°C, and low-temperature heat (LT) 70°C. The emphasis is to maximize the high-quality energy sum PV + HT, while maintaining PV at a high level. A generalized 5-parameter double Fermi model for the HM spectral profile is investigated allowing for a wide parametric range and profile asymmetry. The projected optimized TSC conversion efficiencies are: PV = 14.3%, HT = 43.5%, and LT = 42.2% with a high-quality energy sum of PV + HT = 57.8%. The approach to this optimum HM spectral profile by experimental HM films such as ITO are discussed.

  20. The 8 MW lower hybrid electron mode system for the additional heating of the plasma of the FTU Tokamak

    International Nuclear Information System (INIS)

    Andreani, R.; De Marco, F.; Ferro, C.; Mirizzi, F.; Papitto, P.; Santini, F.; Segre, S.E.; Sassi, M.

    1985-01-01

    The ''Electron Mode'' regime of LH Heating, based on the same physics as the current drive, has been extensively studied and experimentally tested especially with respect to the relation between frequency and density limit. These results have largely contributed to the decision to build a CD system on TORE SUPRA. Based on the same motivations, the Lower Hybrid 'Electron Mode' Heating (frequency: 8 ''Electron Mode'' Heating (frequency: 8 GHz), has been chosen to heat the plasma of the FTU Tokamak. The RF power required (8 MW at 8 GHz) will be produced by 16 gyrotron oscillators (500 KW unit power) feeding 16 grill couplers installed on 8 equatorial ports of FTU. The dc power supplies will be ,odularly built to be compatible even with completely different sort of tubes (e.g. for IRCH). The transmission lines between the generators and the grills will be circular oversized waveguides to reduce the losses to less than 1 dB. Each grill will consist of an 8x8 matrix of rectangular waveguides pressurized and terminated by thik (one wavelength) alumina windows facing the grill mouth. Gyrotron availability has been verified through studies conducted by the two major manufacturers presently on the market. Preliminary quotations and delivery times have been obtained. The design of the grill couplers has been supplemented by a study contract with an industrial research laboratory which is producing a prototype structure and ceramic windows with very promising results. Microwave mode converters and power dividers for the transmission system have been designed and prototypes are being built and will be tested shortly. An 8 GHz, 25 KW cw test bench has been already commissioned and will be used to test all the microwave components. The power level is more than adequate also to process single channels of the coupling structures

  1. A study of photovoltaic/thermal (PVT)-ground source heat pump hybrid system by using fuzzy logic control

    International Nuclear Information System (INIS)

    Andrew Putrayudha, S.; Kang, Eun Chul; Evgueniy, E.; Libing, Y.; Lee, Euy Joon

    2015-01-01

    Renewable Heat Obligation (RHO) implementation in every country becomes an important issue to utilize more renewable energy sources while reducing the usage of fossil fuel. In 2014, South Korea has a target that every commercial building construction that exceeding 10,000 m 2 has to have on-site new & renewable power generation such as combined heat in the beginning of 2016. Photovoltaic/Thermal (PVT) and Geothermal hybrid systems have been introduced in previous research (E.J. Lee et al.) and it showed a great result from its efficiency and also its power consumption for single and multi-building cases. In this paper, Fuzzy Logic control has been applied to optimize the energy consumption of the system. By comparing it with conventional on–off control, fuzzy logic control system shows a better result in reducing primary energy consumption for both heating and cooling systems annually. Two cases were introduced in this paper, GSHP system and PVT–GSHP system with both on–off and fuzzy logic applied respectively. As a result, it shows that fuzzy logic control consumed 13.3% less energy compared with on–off controller for GSHP system annually and 18.3% less energy compared to on–off controller for PVT–GSHP system annually. - Highlights: • Two renewable systems were designed to produce heating, cooling and electricity. • System optimization by applying Fuzzy Logic in terms of energy saving. • Conventional on–off control system vs advance fuzzy logic control system. • Assumption used based on previous research experience, guidelines.

  2. Observation of turbulent spectra during the lower hybrid heating in the WEGA tokamak

    International Nuclear Information System (INIS)

    Takamura, S.; Javel, P.

    1976-11-01

    The application of the R.F. power around the lower hybrid frequency to the WEGA Tokamak produced a turbulent decay spectrum observed by means of pick-up loops placed at various positions around the torus. Characteristics of spectra, for example, threshold levels, a pump depletion, and their cascading nature, are discussed. Some correlations between the appearance of side band around the applied frequency and high energetic ions have been seen. The most excentric part of the plasma surface relative to the torus axis seems to play an important role in the excitation of these instabilities

  3. Integrated power-heat-cold-coupling by switchable Stirling-Vuilleumier-Hybrid-Machines; Integrierte Kraft-Waerme-Kaelte-Kopplung durch umschaltbare Stirling-Vuilleumier-Hybrid-Maschinen

    Energy Technology Data Exchange (ETDEWEB)

    Kuehl, Hans-Detlev [Technische Univ. Dortmund (Germany). Lehrstuhl fuer Thermodynamik

    2017-07-01

    A Stirling engine consists in its so-called Gamma type on the one hand of a thermal compressor in which a double-acting displacer is the working gas between a ''hot'' and a ''warm'' (ie located on the heat use temperature level of the CHP application) cylinder chamber isochoric via a regenerator periodically shuffled back and forth. On the other hand, he has a spatially separated, one-sided working piston-cylinder system, which is connected to the ''warm'' side of the thermal compressor through an overflow and thus is at a similar temperature level. If an additional regenerator is inserted into this overflow channel, then the temperature levels are separated, since the heat output of the process takes place primarily via the warm cylinder space of the displacer system, while the cylinder space of the working piston constitutes a heat sink. This so-called ''hybrid'' process is still characterized by a - compared to the Stirling mode only slightly reduced - mechanical power output, but in addition by a theoretically equal to this magnitude, recorded on the cylinder at ''cold'' temperature cooling capacity, It thus represents an integrated system for power-heat-cold-coupling, which can be realized by a single thermodynamic process. Turning this process in the warm temperature range in addition to another, lying on the back of the working cylinder cylinder space, so that the former becomes a second, double-acting displacer, we finally get the known as a thermally driven heat pump or chiller Vuilleumier process that Ideally, no mechanical power gives or absorbs. At the Chair of Thermodynamics of the TU Dortmund, a research machine was developed and measured in a meanwhile completed research project funded by the DFG, which can switch between the three described processes and thus be adapted to changing power, heat and cooling requirements. In order to reduce the

  4. Alfvén wave heating of heavy ions in the expanding solar wind: Hybrid simulations

    Czech Academy of Sciences Publication Activity Database

    Hellinger, Petr; Velli, M.; Trávníček, Pavel; Gary, S. P.; Goldstein, B. E.; Liewer, P. C.

    2005-01-01

    Roč. 110, - (2005), A12109/1-A12109/11 ISSN 0148-0227 R&D Projects: GA AV ČR IAA3042403 Institutional research plan: CEZ:AV0Z30420517 Keywords : Alfvén waves * solar wind heating * microinstabilities Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 2.784, year: 2005

  5. Performance-oriented Analysis of a Hybrid magnetic Assembly for a Heat-pump Magnetocaloric Device

    DEFF Research Database (Denmark)

    Insinga, Andrea Roberto; Smith, Anders; Bahl, Christian R.H.

    2014-01-01

    Conventional active-regenerator magnetocaloric devices include moving parts, with the purpose of generating an oscillating magnetic field in the magneto-caloric material, placed inside the regenerator. In this work a different design is analyzed, for application in a magnetocaloric heat pump...

  6. Approaches to ultra-low radiation dose coronary artery calcium scoring based on 3rd generation dual-source CT : A phantom study

    NARCIS (Netherlands)

    McQuiston, Andrew D.; Muscogiuri, Giuseppe; Schoepf, U. Joseph; Meinel, Felix G.; Canstein, Christian; Varga-Szemes, Akos; Cannao, Paola M.; Wichmann, Julian L.; Allmendinger, Thomas; Vliegenthart, Rozemarijn; De Cecco, Carlo N.

    Objectives: To investigate to what extent 3rd generation dual-source computed tomography (DSCT) can reduce radiation dose in coronary artery calcium scoring. Methods: Image acquisition was performed using a stationary calcification phantom. Prospectively electrocardiogram (ECG)-triggered 120 kV

  7. Dual Source Time-of-flight Mass Spectrometer and Sample Handling System

    Science.gov (United States)

    Brinckerhoff, W.; Mahaffy, P.; Cornish, T.; Cheng, A.; Gorevan, S.; Niemann, H.; Harpold, D.; Rafeek, S.; Yucht, D.

    We present details of an instrument under development for potential NASA missions to planets and small bodies. The instrument comprises a dual ionization source (laser and electron impact) time-of-flight mass spectrometer (TOF-MS) and a carousel sam- ple handling system for in situ analysis of solid materials acquired by, e.g., a coring drill. This DSTOF instrument could be deployed on a fixed lander or a rover, and has an open design that would accommodate measurements by additional instruments. The sample handling system (SHS) is based on a multi-well carousel, originally de- signed for Champollion/DS4. Solid samples, in the form of drill cores or as loose chips or fines, are inserted through an access port, sealed in vacuum, and transported around the carousel to a pyrolysis cell and/or directly to the TOF-MS inlet. Samples at the TOF-MS inlet are xy-addressable for laser or optical microprobe. Cups may be ejected from their holders for analyzing multiple samples or caching them for return. Samples are analyzed with laser desorption and evolved-gas/electron-impact sources. The dual ion source permits studies of elemental, isotopic, and molecular composition of unprepared samples with a single mass spectrometer. Pulsed laser desorption per- mits the measurement of abundance and isotope ratios of refractory elements, as well as the detection of high-mass organic molecules in solid samples. Evolved gas analysis permits similar measurements of the more volatile species in solids and aerosols. The TOF-MS is based on previous miniature prototypes at JHU/APL that feature high sensitivity and a wide mass range. The laser mode, in which the sample cup is directly below the TOF-MS inlet, permits both ablation and desorption measurements, to cover elemental and molecular species, respectively. In the evolved gas mode, sample cups are raised into a small pyrolysis cell and heated, producing a neutral gas that is elec- tron ionized and pulsed into the TOF-MS. (Any imaging

  8. Radiation dose of cardiac dual-source CT: The effect of tailoring the protocol to patient-specific parameters

    International Nuclear Information System (INIS)

    Alkadhi, Hatem; Stolzmann, Paul; Scheffel, Hans; Desbiolles, Lotus; Baumueller, Stephan; Plass, Andre; Genoni, Michele; Marincek, Borut; Leschka, Sebastian

    2008-01-01

    Objective: To determine the radiation doses and image quality of different dual-source computed tomography coronary angiography (CTCA) protocols tailored to the heart rate (HR) and body mass index (BMI) of the patients. Materials and methods: Two hundred consecutive patients (68 women; mean age 61 ± 9 years) underwent either helical CTCA with retrospective ECG-gating or sequential CT with prospective ECG-triggering: 50 patients (any BMI, any HR) were examined with a standard, non-tailored protocol (helical CTCA, 120 kV, 330 mAs), whereas the other 150 patients were examined with a tailored protocol: 40 patients (group A, BMI ≤ 25 kg/sqm, HR ≤ 70 bpm) with sequential CTCA (100 kV, 190 mAs ref ), 43 patients (group B, BMI ≤ 25 kg/sqm, HR > 70 bpm) with helical CTCA (100 kV, 220 mAs), 28 patients (group C, BMI > 25 kg/sqm, HR ≤ 70 bpm) with sequential CTCA (120 kV, 330 mAs ref ), and 39 patients (group D, BMI > 25 kg/sqm, HR > 70 bpm) with helical CTCA (120 kV, 330 mAs). The effective radiation dose estimates were calculated from the dose-length-product for each patient. Image quality was classified as being diagnostic or non-diagnostic in each coronary segment. Results: Image quality was diagnostic in 2403/2460 (98%) and non-diagnostic in 57/2460 (2%) of all coronary segments. No significant differences in image quality were found among all five CTCA protocols (p = 0.78). The non-tailored helical CTCA protocol was associated with a radiation dose of 9.0 ± 1.0 mSv, being significantly higher compared to that using sequential CTCA (group A: 1.3 ± 0.3 mSv, p 70 bpm (group D: 8.5 ± 0.9 mSv, p = 0.51). Conclusions: Dual-source CTCA is associated with radiation doses ranging between 1.3 and 9.0 mSv, depending on the protocol used. Tailoring of the CTCA protocol to the HR and BMI of the individual patient results in dose reductions of up to 86%, while maintaining a diagnostic image quality of the examination

  9. Accuracy of iodine quantification using dual energy CT in latest generation dual source and dual layer CT.

    Science.gov (United States)

    Pelgrim, Gert Jan; van Hamersvelt, Robbert W; Willemink, Martin J; Schmidt, Bernhard T; Flohr, Thomas; Schilham, Arnold; Milles, Julien; Oudkerk, Matthijs; Leiner, Tim; Vliegenthart, Rozemarijn

    2017-09-01

    To determine the accuracy of iodine quantification with dual energy computed tomography (DECT) in two high-end CT systems with different spectral imaging techniques. Five tubes with different iodine concentrations (0, 5, 10, 15, 20 mg/ml) were analysed in an anthropomorphic thoracic phantom. Adding two phantom rings simulated increased patient size. For third-generation dual source CT (DSCT), tube voltage combinations of 150Sn and 70, 80, 90, 100 kVp were analysed. For dual layer CT (DLCT), 120 and 140 kVp were used. Scans were repeated three times. Median normalized values and interquartile ranges (IQRs) were calculated for all kVp settings and phantom sizes. Correlation between measured and known iodine concentrations was excellent for both systems (R = 0.999-1.000, p < 0.0001). For DSCT, median measurement errors ranged from -0.5% (IQR -2.0, 2.0%) at 150Sn/70 kVp and -2.3% (IQR -4.0, -0.1%) at 150Sn/80 kVp to -4.0% (IQR -6.0, -2.8%) at 150Sn/90 kVp. For DLCT, median measurement errors ranged from -3.3% (IQR -4.9, -1.5%) at 140 kVp to -4.6% (IQR -6.0, -3.6%) at 120 kVp. Larger phantom sizes increased variability of iodine measurements (p < 0.05). Iodine concentration can be accurately quantified with state-of-the-art DECT systems from two vendors. The lowest absolute errors were found for DSCT using the 150Sn/70 kVp or 150Sn/80 kVp combinations, which was slightly more accurate than 140 kVp in DLCT. • High-end CT scanners allow accurate iodine quantification using different DECT techniques. • Lowest measurement error was found in scans with largest photon energy separation. • Dual-source CT quantified iodine slightly more accurately than dual layer CT.

  10. Assessment of radiation exposure on a dual-source computed tomography-scanner performing coronary computed tomography-angiography

    International Nuclear Information System (INIS)

    Kirchhoff, S.; Herzog, P.; Johnson, T.; Boehm, H.; Nikolaou, K.; Reiser, M.F.; Becker, C.H.

    2010-01-01

    Objective: The radiation exposure of a dual-source-64-channel multi-detector-computed-tomography-scanner (Somatom-Defintion, Siemens, Germany) was assessed in a phantom-study performing coronary-CT-angiography (CTCA) in comparison to patients' data randomly selected from routine scanning. Methods: 240 CT-acquisitions of a computed tomography dose index (CTDI)-phantom (PTW, Freiburg, Germany) were performed using a synthetically generated Electrocardiography (ECG)-signal with variable heart rates (30-180 beats per minute (bpm)). 120 measurements were acquired using continuous tube-output; 120 measurements were performed using ECG-synchronized tube-modulation. The pulsing window was set at minimum duration at 65% of the cardiac cycle between 30 and 75 bpm. From 90-180 bpm the pulsing window was set at 30-70% of the cardiac cycle. Automated pitch adaptation was always used. A comparison between phantom CTDI and two patient groups' CTDI corresponding to the two pulsing groups was performed. Results: Without ECG-tube-modulation CDTI-values were affected by heart-rate-changes resulting in 85.7 mGray (mGy) at 30 and 45 bpm, 65.5 mGy/60 bpm, 54.7 mGy/75 bpm, 46.5 mGy/90 bpm, 34.2 mGy/120 bpm, 27.0 mGy/150 bpm and 22.1 mGy/180 bpm equal to effective doses between 14.5 mSievert (mSv) at 30/45 bpm and 3.6 mSv at 180 bpm. Using ECG-tube-modulation these CTDI-values resulted: 32.6 mGy/30 bpm, 36.6 mGy/45 bpm, 31.4 mGy/60 bpm, 26.8 mGy/75 bpm, 23.7 mGy/90 bpm, 19.4 mGy/120 bpm, 17.2 mGy/150 bpm and 15.6 mGy/180 bpm equal to effective doses between 5.5 mSv at 30 bpm and 2.6 mSv at 180 bpm. Significant CTDI-differences were found between patients with lower/moderate and higher heart rates in comparison to the phantom CTDI-results. Conclusions: Dual source CTCA is particularly dose efficient at high heart rates when automated pitch adaptation, especially in combination with ECG-based tube-modulation is used. However in clinical routine scanning for patients with higher heart rates

  11. Analysis of Heat Transfer in Power Split Device for Hybrid Electric Vehicle Using Thermal Network Method

    Directory of Open Access Journals (Sweden)

    Jixin Wang

    2014-06-01

    Full Text Available This paper presents a rational prediction of temperature field on the differential hybrid system (DHS based on the thermal network method (TNM. The whole thermal network model is built by considering both the contact thermal resistance between gasket and planet gear and the temperature effect on the physical property parameters of lubricant. The contact thermal resistance is obtained by using the concept of contact branch thermal resistance and G-W elastic model. By building an elaborate thermal network model and computing models for power losses and thermal resistances between components, the whole temperature field of DHS under typical operating condition is predicted. Results show that thermal network method can be effectively used to predict the temperature distribution and the rule of temperature variation, the surface roughness significantly affects contact thermal conduction, and the decrease in the thermal resistance of the natural convection between air and DHS housing can effectively improve the thermal environment of DHS.

  12. Closing in on the K Edge : Coronary CT Angiography at 100, 80, and 70 kV-Initial Comparison of a Second-versus a Third-Generation Dual-Source CT System

    NARCIS (Netherlands)

    Meyer, Mathias; Haubenreisser, Holger; Schoepf, U. Joseph; Vliegenthart, Rozemarijn; Leidecker, Christianne; Allmendinger, Thomas; Lehmann, Ralf; Sudarski, Sonja; Borggrefe, Martin; Schoenberg, Stefan O.; Henzler, Thomas

    2014-01-01

    Purpose: To prospectively evaluate radiation and contrast medium requirements for performing high-pitch coronary computed tomographic (CT) angiography at 70 kV using a third-generation dual-source CT system in comparison to a second-generation dual-source CT system. Materials and Methods: All

  13. Efficacy of a dynamic collimator for overranging dose reduction in a second- and third-generation dual source CT scanner

    Energy Technology Data Exchange (ETDEWEB)

    Booij, Ronald; Dijkshoorn, Marcel L.; Straten, Marcel van [Erasmus MC, Department of Radiology and Nuclear Medicine, P.O. Box 2240, Rotterdam (Netherlands)

    2017-09-15

    The purpose of this study was to assess the efficacy of the renewed dynamic collimator in a third-generation dual source CT (DSCT) scanner and to determine the improvements over the second-generation scanner. Collimator efficacy is defined as the percentage overranging dose in terms of dose-length product (DLP) that is blocked by the dynamic collimator relative to the total overranging dose in case of a static collimator. Efficacy was assessed at various pitch values and different scan lengths. The number of additional rotations due to overranging and effective scan length were calculated on the basis of reported scanning parameters. On the basis of these values, the efficacy of the collimator was calculated. The second-generation scanner showed decreased performance of the dynamic collimator at increasing pitch. Efficacy dropped to 10% at the highest pitch. For the third-generation scanner the efficacy remained above 50% at higher pitch. Noise was for some pitch values slightly higher at the edge of the imaged volume, indicating a reduced scan range to reduce the overranging dose. The improved dynamic collimator in the third-generation scanner blocks the overranging dose for more than 50% and is more capable of shielding radiation dose, especially in high pitch scan modes. (orig.)

  14. Efficacy of a dynamic collimator for overranging dose reduction in a second- and third-generation dual source CT scanner

    International Nuclear Information System (INIS)

    Booij, Ronald; Dijkshoorn, Marcel L.; Straten, Marcel van

    2017-01-01

    The purpose of this study was to assess the efficacy of the renewed dynamic collimator in a third-generation dual source CT (DSCT) scanner and to determine the improvements over the second-generation scanner. Collimator efficacy is defined as the percentage overranging dose in terms of dose-length product (DLP) that is blocked by the dynamic collimator relative to the total overranging dose in case of a static collimator. Efficacy was assessed at various pitch values and different scan lengths. The number of additional rotations due to overranging and effective scan length were calculated on the basis of reported scanning parameters. On the basis of these values, the efficacy of the collimator was calculated. The second-generation scanner showed decreased performance of the dynamic collimator at increasing pitch. Efficacy dropped to 10% at the highest pitch. For the third-generation scanner the efficacy remained above 50% at higher pitch. Noise was for some pitch values slightly higher at the edge of the imaged volume, indicating a reduced scan range to reduce the overranging dose. The improved dynamic collimator in the third-generation scanner blocks the overranging dose for more than 50% and is more capable of shielding radiation dose, especially in high pitch scan modes. (orig.)

  15. Dual-energy CT characteristics of colon and rectal cancer allows differentiation from stool by dual-source CT.

    Science.gov (United States)

    Özdeniz, İlknur; İdilman, İlkay S; Köklü, Seyfettin; Hamaloğlu, Erhan; Özmen, Mustafa; Akata, Deniz; Karçaaltıncaba, Muşturay

    2017-01-01

    We aimed to determine dual-energy computed tomography (DECT) characteristics of colorectal cancer and investigate effectiveness of DECT method in differentiating tumor from stool in patients with colorectal cancer. Fifty consecutive patients with colorectal tumors were enrolled. Staging was performed by DECT (80-140 kV) using dual-source CT after rectal air insufflation and without bowel preparation. Both visual and quantitative analyses were performed at 80 kV and 140 kV, on iodine map and virtual noncontrast (VNC) images. All colorectal tumors had homogeneous pattern on iodine map. Stools demonstrated heterogeneous pattern in 86% (43/50) and homogeneous pattern in 14% (7/50) on iodine maps and were less visible on VNC images. Median density of tumors was 54 HU (18-100 HU) on iodine map and 28 HU (11-56 HU) on VNC images. Median density of stool was 36.5 HU (8-165 HU) on iodine map and -135.5 HU (-438 HU to -13 HU) on VNC images. The density of stools was significantly lower than tumors on both iodine map and VNC images (P VNC images was -1 HU with area under the curve of 1 and a sensitivity and specificity of 100%. Density or visual analysis of iodine map and VNC DECT images allow accurate differentiation of tumor from stool.

  16. Comparison of diagnostic accuracy of dual-source CT and conventional angiography in detecting congenital heart diseases

    International Nuclear Information System (INIS)

    Sedaghat, Fariborz; Pouraliakbar, Hamidreza; Motevalli, Marzieh; Karimi, Mohammad Ali; Armand, Sandbad

    2014-01-01

    Cardiac dual-source computed tomography (DSCT) is primarily used for coronary arteries. There are limited studies about the application of DSCT for congenital heart diseases. The aim of this study was to determine the diagnostic value of DSCT in the cardiac anomalies. The images of DSCTs and conventional angiographies of 36 patients (21 male; mean age: 8.5 month) with congenital heart diseases were reviewed and the parameters of diagnostic value of these methods were compared. Cardiac surgery was the gold standard. A total of 105 cardiac anomalies were diagnosed at surgery. Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of DSCT were 98.25%, 97.9%, 98.1%, 99.07%, and 98.2%, respectively. The corresponding values of angiography were 95.04%, 98.7%, 97.8%, 98.1%, and 98%, respectively. Only one atrial septal defect (ASD) and two patent ductus arteriosus (PDA) were missed by DSCT. Angiography missed two ASD and two PDA. DSCT also provided important additional findings (n=35) about the intrathoracic or intraabdominal organs. DSCT is a highly accurate diagnostic modality for congenital heart diseases, obviating the need for invasive modalities. Beside its noninvasive nature, the advantage of DSCT over the angiography is its ability to provide detailed anatomical information about the heart, vessels, lungs and intraabdominal organs

  17. Image quality analysis to reduce dental artifacts in head and neck imaging with dual-source computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Ketelsen, D.; Werner, M.K.; Thomas, C.; Tsiflikas, I.; Reimann, A.; Claussen, C.D.; Heuschmid, M. [Tuebingen Univ. (Germany). Abt. fuer Diagnostische und Interventionelle Radiologie; Koitschev, A. [Tuebingen Univ. (Germany). Abt. fuer Hals-Nasen-Ohrenheilkunde

    2009-01-15

    Purpose: Important oropharyngeal structures can be superimposed by metallic artifacts due to dental implants. The aim of this study was to compare the image quality of multiplanar reconstructions and an angulated spiral in dual-source computed tomography (DSCT) of the neck. Materials and Methods: Sixty-two patients were included for neck imaging with DSCT. MPRs from an axial dataset and an additional short spiral parallel to the mouth floor were acquired. Leading anatomical structures were then evaluated with respect to the extent to which they were affected by dental artifacts using a visual scale, ranging from 1 (least artifacts) to 4 (most artifacts). Results: In MPR, 87.1 % of anatomical structures had significant artifacts (3.12 {+-} 0.86), while in angulated slices leading anatomical structures of the oropharynx showed negligible artifacts (1.28 {+-} 0.46). The diagnostic growth due to primarily angulated slices concerning artifact severity was significant (p < 0.01). Conclusion: MPRs are not capable of reducing dental artifacts sufficiently. In patients with dental artifacts overlying the anatomical structures of the oropharynx, an additional short angulated spiral parallel to the floor of the mouth is recommended and should be applied for daily routine. As a result of the static gantry design of DSCT, the use of a flexible head holder is essential. (orig.)

  18. Radio frequency plasma heating in large tokamak systems near the lower hybrid resonance

    International Nuclear Information System (INIS)

    Deitz, A.; Hooke, W.M.

    1975-01-01

    The frequency range, power, efficiency, and pulse length of a high power rf system are discussed as they might be applied to the TFTR Tokamak facility as well as on a full scale reactor. Comparisons are made of the size, power output, and costs to obtain microwave power sufficient to satisfy the physics requirements. A new microwave feed concept is discussed which will improve the coupling of the microwave energy into the plasma. The unique advantages of waveguide feed systems is apparent when one considers the practical problems associated with coupling supplementary heating energy into a reactor

  19. Dual-source computed tomography. Effect on regional and global left ventricular function assessment compared to magnetic resonance imaging; Untersuchung der regionalen und globalen linksventrikulaeren Funktion mit der Dual-Source-Computertomografie im Vergleich zur Magnetresonanztomografie

    Energy Technology Data Exchange (ETDEWEB)

    Lueders, F.; Seifarth, H.; Wessling, J.; Heindel, W.; Juergens, Kai Uwe [Inst. fuer Klinische Radiologie, Universitaetsklinikum Muenster (Germany); Fischbach, R. [Klinik fuer Radiologie, Nuklearmedizin und Neuroradiologie, Asklepios Klinik Altona (Germany)

    2009-10-15

    Purpose: to determine regional and global left ventricular (LV) functional parameters and to perform segmental wall thickness (SWT) and motion (WM) analysis of dual source CT (DSCT) with optimized temporal resolution versus MRI. Materials and Methods: 30 patients with known or suspected CAD, non-obstructive HCM, DCM, ARVCM, Fallot Tetralogy, cardiac sarcoidosis and cardiac metastasis underwent DSCT and MRI. The DSCT and MR images were evaluated: end-systolic (ESV), end-diastolic LV (EDV) volumes, stroke volume (SV), ejection fraction (EF), and myocardial mass (MM) as well as LV wall thickening and segmental WM applying the AHA model were obtained and statistically analyzed. Results: The mean LV-EDV (r = 0.96) and ESV (r = 0.98) as well as LV-EF (r = 0.97), SV (r = 0.83), and MM (r = 0.95) correlated well. Bland Altman analysis revealed little systematic underestimation of LV-EF (-1.1 {+-} 7.8%), EDV (-0.3 {+-} 18.2 ml), SV (-1.3 {+-} 16.7 ml) and little overestimation of ESV (1.1 {+-} 7.8 ml) and MM (12.8 {+-} 14.4 g) determined by DSCT. Systolic reconstruction time points correlated well (DSCT 32.2 {+-} 6.7 vs. MRI 35.6 {+-} 4.4% RR-interval). The LV wall thickness obtained by DSCT and MRI showed close correlation in all segments (diameter diff 0.42 {+-} 1 mm). In 413 segments (89%) WM abnormalities were equally rated, whereas DSCT tended to underestimate the degree of wall motion impairment. Conclusion: DSCT with optimized temporal resolution enables regional and global LV function analysis as well as segmental WM analysis in good correlation with MRI. However, the degree of WM impairment is slightly underestimated by DSCT. (orig.)

  20. Power and phase monitoring system for the lower hybrid phased array heating system on ATC machine

    International Nuclear Information System (INIS)

    Reed, B.W.

    1975-01-01

    A four waveguide phased array slow wave structure has been constructed to couple microwave energy into plasma in the ATC Tokamac at Princeton. Theory has indicated that the coupling of power into the plasma column is a strong function of the imposed fourier spectrum at the antenna aperture. To optimize heating, and to verify theoretical results, a precision amplitude and phase monitoring system has been designed and constructed. The system data output is routed to an IBM 1800 computer where the fourier spectrum in n/sub parallel/ space is computed for discrete increments of time during an RF pulse. Computer output data is used to update the adjustment of transmission line parameters in between pulses

  1. Dry sliding wear behavior of heat treated hybrid metal matrix composite using Taguchi techniques

    International Nuclear Information System (INIS)

    Kiran, T.S.; Prasanna Kumar, M.; Basavarajappa, S.; Viswanatha, B.M.

    2014-01-01

    Highlights: • ZA-27 alloy is used as matrix material and reinforced with SiC and Gr particles. • Heat treatment was carried out for all specimen. • Dry sliding wear test was done on pin-on-disc apparatus by Taguchi technique. • ZA-27/9SiC–3Gr showed superior wear resistance over the base alloy. • Ceramic mixed mechanical layer on contact surface of composite was formed. - Abstract: Dry sliding wear behavior of zinc based alloy and composite reinforced with SiCp (9 wt%) and Gr (3 wt%) fabricated by stir casting method was investigated. Heat treatment (HT) and aging of the specimen were carried out, followed by water quenching. Wear behavior was evaluated using pin on disc apparatus. Taguchi technique was used to estimate the parameters affecting the wear significantly. The effect of HT was that it reduced the microcracks, residual stresses and improved the distribution of microconstituents. The influence of various parameters like applied load, sliding speed and sliding distance on wear behavior was investigated by means and analysis of variance (ANOVA). Further, correlation between the parameters was determined by multiple linear regression equation for each response. It was observed that the applied load significantly influenced the wear volume loss (WVL), followed by sliding speed implying that increase in either applied load or sliding speed increases the WVL. Whereas for composites, sliding distance showed a negative influence on wear indicating that increase in sliding distance reduces WVL due to the presence of reinforcements. The wear mechanism of the worn out specimen was analyzed using scanning electron microscopy. The analysis shows that the formation and retention of ceramic mixed mechanical layer (CMML) plays a major role in the dry sliding wear resistance

  2. A study of quasi-mode parametric excitations in lower-hybrid heating of tokamak plasmas

    International Nuclear Information System (INIS)

    Villalon, E.; Bers, A.

    1980-01-01

    A detailed linear and non-linear analysis of quasi-mode parametric excitations relevant to experiments in supplementary heating of tokamak plasmas is presented. The linear analysis includes the full ion-cyclotron harmonic quasi-mode spectrum. The non-linear analysis, considering depletion of the pump electric field, is applied to the recent Alcator A heating experiment. Because of the very different characteristics of a tokamak plasma near the wall (in the shadow of the limiter) and inside, the quasi-mode excitations are studied independently for the plasma edge and the main bulk of the plasma, and for two typical regimes in overall density, the low (peak in density, n 0 =1.5x10 14 cm -3 ) and high (n 0 =5x10 14 cm -3 ) density regimes. At the edge of the plasma and for the low-density regime, it is found that higher nsub(z)(nsub(z)=cksub(z)/ω) than those predicted by the linear theory are strongly excited. Inside the plasma, the excitation of higher wave numbers is also significant. These results indicate that a large amount of the RF-power may not penetrate to the plasma centre, but will rather be either Landau-damped on the electrons or mode-converted into thermal modes, close to the plasma edge. Moreover, for sufficiently high peaks in density, it is found that all the RF-power is mode-converted before reaching the plasma centre. Inside the plasma, the power density of the excited sideband fields is shown to be always very small in comparison with their excitation at the plasma edge. (author)

  3. Study on hybrid ground-coupled heat pump system for air-conditioning in hot-weather areas like Hong Kong

    International Nuclear Information System (INIS)

    Man, Yi; Yang, Hongxing; Wang, Jinggang

    2010-01-01

    The ground-coupled heat pump (GCHP) system is becoming attractive for air-conditioning in some moderate-weather regions due to its high energy efficiency and reliable operation capability. However, when the technology is used in buildings where there is only cooling load in hot-weather areas like Hong Kong, the heat rejected into the ground by the GCHP systems will accumulate around the ground heat exchangers (GHE). This heat accumulation will result in degradation of system performance and increment of system operating costs. This problem can be resolved by using the hybrid ground-coupled heat pump (HGCHP) system, which uses supplemental heat rejecters to reject the accumulated heat. This paper presents a practical hourly simulation model of the HGCHP system by modeling the heat transfer process of the system's main components. The computer program based on this hourly simulation model can be used to calculate the hour-by-hour operation data of the HGCHP system. As a case study, both a HGCHP system and a traditional GCHP system are designed for a hypothetic private residential building located in Hong Kong, and the economic comparisons are conducted between these two types of systems. The simulation results show that the HGCHP system can effectively solve the heat accumulation problem and reduce both the initial costs and operating costs of the air-conditioning system in the building.

  4. Study on hybrid ground-coupled heat pump system for air-conditioning in hot-weather areas like Hong Kong

    Energy Technology Data Exchange (ETDEWEB)

    Man, Yi; Yang, Hongxing [Renewable Energy Research Group, Department of Building Services Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong (China); Wang, Jinggang [Hebei University of Engineering, Handan (China)

    2010-09-15

    The ground-coupled heat pump (GCHP) system is becoming attractive for air-conditioning in some moderate-weather regions due to its high energy efficiency and reliable operation capability. However, when the technology is used in buildings where there is only cooling load in hot-weather areas like Hong Kong, the heat rejected into the ground by the GCHP systems will accumulate around the ground heat exchangers (GHE). This heat accumulation will result in degradation of system performance and increment of system operating costs. This problem can be resolved by using the hybrid ground-coupled heat pump (HGCHP) system, which uses supplemental heat rejecters to reject the accumulated heat. This paper presents a practical hourly simulation model of the HGCHP system by modeling the heat transfer process of the system's main components. The computer program based on this hourly simulation model can be used to calculate the hour-by-hour operation data of the HGCHP system. As a case study, both a HGCHP system and a traditional GCHP system are designed for a hypothetic private residential building located in Hong Kong, and the economic comparisons are conducted between these two types of systems. The simulation results show that the HGCHP system can effectively solve the heat accumulation problem and reduce both the initial costs and operating costs of the air-conditioning system in the building. (author)

  5. Study on hybrid ground-coupled heat pump system for air-conditioning in hot-weather areas like Hong Kong

    Energy Technology Data Exchange (ETDEWEB)

    Man, Y.; Yang, H.X. [Hong Kong Polytechnic Univ., Renewable Energy Research Group, Hung Hom, Kowloon, (Hong Kong). Dept. of Building Services Engineering

    2008-07-01

    Due to its high energy efficiency and reliable operation capability, the ground-coupled heat pump (GCHP) system is becoming attractive for air-conditioning in some moderate-weather regions. However, when the technology is used in buildings where there is only cooling load in hot-weather areas such as Hong Kong, the heat rejected into the ground by the GCHP systems will accumulate around the ground heat exchangers (GHE), resulting in degradation of system performance and increased system operating costs. This problem can be resolved by using a hybrid ground-coupled heat pump (HGCHP) system, as it uses supplemental heat rejecters to reject the accumulated heat. By modeling the heat transfer process of the system's main components, this paper presented a practical hourly simulation model of the HGCHP system. Based on this hourly simulation model, the computer program could be used to calculate the hour-by-hour operation data of the HGCHP system according to the cooling and hot water heating loads of a building. The paper discussed a case study that involved a design of both a HGCHP system and a traditional GCHP system for a hypothetical private residential building located in Hong Kong. The economic comparisons were performed between these two types of systems. It was concluded through the simulations that the HGCHP system could effectively solve the heat accumulation problem and reduce both the initial cost and operating cost of the air-conditioning system in the building. 19 refs., 1 tab., 13 figs.

  6. Evaluation of high-pitch dual-source CT angiography for evaluation of coronary and carotid-cerebrovascular arteries

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Kai [Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China); Li, Kuncheng, E-mail: cjr.likuncheng@vip.163.com [Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China); Han, Ruijuan [Department of Cardiology, Chaoyang Hospital, Capital Medical University, Beijing 100020 (China); Li, Wenhuan; Chen, Nan; Yang, Qi; Du, Xiangying; Wang, Chen [Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China); Liu, Guorong; Li, Yuechun [Department of Neurology Baotou Central Hospital, Inner Mongolia, Baotou 014040 (China); Zhou, Maorong [Department of Radiology, Baotou Central Hospital, Inner Mongolia, Baotou 014040 (China); Li, Ligang; Heidrun, Endt [CT BM Clinic Marketing, Siemens Healthcare, Beijing 100102 (China)

    2015-03-15

    Objectives: To explore the feasibility and diagnostic accuracy of a combined one-step high-pitch dual-source computed tomography angiography (CTA) technique for evaluation of coronary and carotid-cerebrovascular arteries. Materials and methods: 85 symptomatic patients suspected of coronary artery and cerebrovascular disease referred for simultaneous coronary and carotid-cerebrovascular CTA were included. Additional invasive angiography of the coronary and cerebral arteries was performed within 30 days in 23 and 13 patients, respectively. The objective parameters of image quality, the mean CT attenuations, image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were evaluated. The subjective image quality of vessels was also assessed by 2 independent radiologists blinded to the patients’ medical history and scan protocols. The diagnostic performance of CTA including sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for the detection or exclusion of significant artery stenosis was calculated using the chi-squared test of contingency and correlated with the results of invasive angiography representing the standard of reference. Results: Image quality was rated excellent (score 1) in 95.3% (1074/1127), good (score 2) in 3.3% (37/1127), adequate (score 3) in 1.0% (11/1127), and non-diagnostic (score 4) in 0.4% (5/1127) of coronary segments. Image quality of carotid and cerebral vessels was rated mostly excellent (score 1, 95.12% [78/82]; score 2, 3.66% [3/82]; score 3, 1.22% [1/82]). The sensitivity, specificity, PPV and NPV for the detection of coronary stenosis were 92.2% (81.1–97.7%), 95.2% (91.7–97.5%), 79.6% (67.1–89.1%) and 98.3% (95.8–99.5%), respectively. For the detection of carotid and cerebral artery stenosis, CTA demonstrated a sensitivity of 92.8% (80.5–98.4%), a specificity of 93.5% (88.3–96.8%), a PPV of 79.6% (65.6–89.7%) and a NPV of 97.9% (94.1–99.5%). The effective

  7. Radiofrequency plasma heating: proceedings

    International Nuclear Information System (INIS)

    Swenson, D.G.

    1985-01-01

    The conference proceedings include sessions on Alfven Wave Heating, ICRF Heating and Current Drive, Lower Hybrid Heating and Current Drive, and ECRF Heating. Questions of confinement, diagnostics, instabilities and technology are considered. Individual papers are cataloged separately

  8. Energy and exergy analyses on a novel hybrid solar heating, cooling and power generation system for remote areas

    International Nuclear Information System (INIS)

    Zhai, H.; Dai, Y.J.; Wu, J.Y.; Wang, R.Z.

    2009-01-01

    In this study, a small scale hybrid solar heating, chilling and power generation system, including parabolic trough solar collector with cavity receiver, a helical screw expander and silica gel-water adsorption chiller, etc., was proposed and extensively investigated. The system has the merits of effecting the power generation cycle at lower temperature level with solar energy more efficiently and can provide both thermal energy and power for remote off-grid regions. A case study was carried out to evaluate an annual energy and exergy efficiency of the system under the climate of northwestern region of China. It is found that both the main energy and exergy loss take place at the parabolic trough collector, amount to 36.2% and 70.4%, respectively. Also found is that the studied system can have a higher solar energy conversion efficiency than the conventional solar thermal power generation system alone. The energy efficiency can be increased to 58.0% from 10.2%, and the exergy efficiency can be increased to 15.2% from 12.5%. Moreover, the economical analysis in terms of cost and payback period (PP) has been carried out. The study reveals that the proposed system the PP of the proposed system is about 18 years under present energy price conditions. The sensitivity analysis shows that if the interest rate decreases to 3% or energy price increase by 50%, PP will be less than 10 years. (author)

  9. Dual-Source CT Angiography of Peripheral Arterial Stents: In Vitro Evaluation of 22 Different Stent Types

    Directory of Open Access Journals (Sweden)

    Michael Köhler

    2011-01-01

    Full Text Available Purpose. To test different peripheral arterial stents using four image reconstruction approaches with respect to lumen visualization, lumen attenuation and image noise in dual-source multidetector row CT (DSCT in vitro. Methods and Materials. 22 stents (nitinol, steel, cobalt-alloy, tantalum, platinum alloy were examined in a vessel phantom. All stents were imaged in axial orientation with standard parameters. Image reconstructions were obtained with four different convolution kernels. To evaluate visualization characteristics of the stent, the lumen diameter, intraluminal density and noise were measured. Results. The mean percentage of the visible stent lumen diameter from the nominal stent diameter was 74.5% ± 5.7 for the medium-sharp kernel, 72.8% ± 6.4 for the medium, 70.8% ± 6.4 for the medium-smooth and 67.6% ± 6.6 for the smooth kernel. Mean values of lumen attenuation were 299.7HU ± 127 (medium-sharp, 273.9HU ± 68 (medium, 270.7HU ± 53 (medium-smooth and 265.8HU ± 43. Mean image noise was: 54.6 ± 6.3, 20.5 ± 1.7, 16.3 ± 1.7, 14.0 ± 2 respectively. Conclusion. Visible stent lumen diameter varies depending on stent type and scan parameters. Lumen diameter visibility increases with the sharpness of the reconstruction kernel. Smoother kernels provide more realistic density measurements inside the stent lumen and less image noise.

  10. Low contrast medium-volume third-generation dual-source computed tomography angiography for transcatheter aortic valve replacement planning

    Energy Technology Data Exchange (ETDEWEB)

    Felmly, Lloyd M. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Medical University of South Carolina, Division of Cardiothoracic Surgery, Department of Surgery, Charleston, SC (United States); De Cecco, Carlo N.; Varga-Szemes, Akos; McQuiston, Andrew D. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Schoepf, U.J.; Litwin, Sheldon E.; Bayer, Richard R. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Medical University of South Carolina, Division of Cardiology, Department of Medicine, Charleston, SC (United States); Mangold, Stefanie [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); University Hospital of Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany); Vogl, Thomas J. [University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt (Germany); Wichmann, Julian L. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt (Germany)

    2017-05-15

    To investigate feasibility, image quality and safety of low-tube-voltage, low-contrast-volume comprehensive cardiac and aortoiliac CT angiography (CTA) for planning transcatheter aortic valve replacement (TAVR). Forty consecutive TAVR candidates prospectively underwent combined CTA of the aortic root and vascular access route (270 mgI/ml iodixanol). Patients were assigned to group A (second-generation dual-source CT [DSCT], 100 kV, 60 ml contrast, 4.0 ml/s flow rate) or group B (third-generation DSCT, 70 kV, 40 ml contrast, 2.5 ml/s flow rate). Vascular attenuation, noise, signal-to-noise (SNR) and contrast-to-noise ratios (CNR) were compared. Subjective image quality was assessed by two observers. Estimated glomerular filtration (eGFR) at CTA and follow-up were measured. Besides a higher body-mass-index in group B (24.8±3.8 kg/m{sup 2} vs. 28.1±5.4 kg/m{sup 2}, P=0.0339), patient characteristics between groups were similar (P≥0.0922). Aortoiliac SNR (P=0.0003) was higher in group B. Cardiac SNR (P=0.0003) and CNR (P=0.0181) were higher in group A. Subjective image quality was similar (P≥0.213) except for aortoiliac image noise (4.42 vs. 4.12, P=0.0374). TAVR-planning measurements were successfully obtained in all patients. There were no significant changes in eGFR among and between groups during follow-up (P≥0.302). TAVR candidates can be safely and effectively evaluated by a comprehensive CTA protocol with low contrast volume using low-tube-voltage acquisition. (orig.)

  11. Imaging of pulmonary vein anatomy using low-dose prospective ECG-triggered dual-source computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Blanke, Philipp; Baumann, Tobias; Langer, Mathias; Pache, Gregor [University Hospital Freiburg, Department of Diagnostic Radiology, Freiburg (Germany)

    2010-08-15

    To prospectively investigate the feasibility, image quality and radiation dose estimates for computed tomography angiography (CTA) of the pulmonary veins and left atrium using prospective electrocardiography (ECG)-triggered sequential dual-source (DS) data acquisition at end-systole in patients with paroxysmal atrial fibrillation undergoing radiofrequency ablation. Thirty-five patients (mean age 66.2 {+-} 12.6 years) with paroxysmal atrial fibrillation underwent prospective ECG-triggered sequential DS-CTA with tube current (250 mAs/rotation) centred 250 ms past the R-peak. Tube voltage was adjusted to the BMI (<25 kg/m{sup 2}: 100 kV, >25 kg/m{sup 2}: 120 kV). Presence of motion or stair-step artefacts was assessed. Effective radiation dose was calculated from the dose-length product. All data sets could be integrated into the electroanatomical mapping system. Twenty-two patients (63%) were in sinus rhythm (mean heart rate 69.2 {+-} 11.1 bpm, variability 1.0 {+-} 1.7 bpm) and 13 (37%) showed an ECG pattern of atrial fibrillation (mean heart rate 84.8 {+-} 16.6 bpm, variability 17.9 {+-} 7.5 bpm). Minor step artefacts were observed in three patients (23%) with atrial fibrillation. Mean estimated effective dose was 1.1 {+-} 0.3 and 3.0 {+-} 0.5 mSv for 100 and 120 kV respectively. Imaging of pulmonary vein anatomy is feasible using prospective ECG-triggered sequential data acquisition at end-systole regardless of heart rate or rhythm at the benefit of low radiation dose. (orig.)

  12. Imaging of pulmonary vein anatomy using low-dose prospective ECG-triggered dual-source computed tomography

    International Nuclear Information System (INIS)

    Blanke, Philipp; Baumann, Tobias; Langer, Mathias; Pache, Gregor

    2010-01-01

    To prospectively investigate the feasibility, image quality and radiation dose estimates for computed tomography angiography (CTA) of the pulmonary veins and left atrium using prospective electrocardiography (ECG)-triggered sequential dual-source (DS) data acquisition at end-systole in patients with paroxysmal atrial fibrillation undergoing radiofrequency ablation. Thirty-five patients (mean age 66.2 ± 12.6 years) with paroxysmal atrial fibrillation underwent prospective ECG-triggered sequential DS-CTA with tube current (250 mAs/rotation) centred 250 ms past the R-peak. Tube voltage was adjusted to the BMI ( 2 : 100 kV, >25 kg/m 2 : 120 kV). Presence of motion or stair-step artefacts was assessed. Effective radiation dose was calculated from the dose-length product. All data sets could be integrated into the electroanatomical mapping system. Twenty-two patients (63%) were in sinus rhythm (mean heart rate 69.2 ± 11.1 bpm, variability 1.0 ± 1.7 bpm) and 13 (37%) showed an ECG pattern of atrial fibrillation (mean heart rate 84.8 ± 16.6 bpm, variability 17.9 ± 7.5 bpm). Minor step artefacts were observed in three patients (23%) with atrial fibrillation. Mean estimated effective dose was 1.1 ± 0.3 and 3.0 ± 0.5 mSv for 100 and 120 kV respectively. Imaging of pulmonary vein anatomy is feasible using prospective ECG-triggered sequential data acquisition at end-systole regardless of heart rate or rhythm at the benefit of low radiation dose. (orig.)

  13. Multi-slice and dual-source CT in cardiac imaging. Principles - protocols - indications - outlook. 2. ed.

    International Nuclear Information System (INIS)

    Ohnesorge, B.M.; Flohr, T.G.; Becker, C.R.; Reiser, M.F.; Knez, A

    2007-01-01

    Cardiac diseases, and in particular coronary artery disease, are the leading cause of death and morbidity in industrialized countries. The development of non-invasive imaging techniques for the heart and the coronary arteries has been considered a key element in improving patient care. A breakthrough in cardiac imaging using CT occurred in 1998, with the introduction of multi-slice computed tomography (CT). Since then, amazing advances in performance have taken place with scanners that acquire up to 64 slices per rotation. This book discusses the state-of-the-art developments in multi-slice CT for cardiac imaging as well as those that can be anticipated in the future. It serves as a comprehensive work that covers all aspects of this technology, from the technical fundamentals and image evaluation all the way to clinical indications and protocol recommendations. This fully reworked second edition draws on the most recent clinical experience obtained with 16- and 64-slice CT scanners by world-leading experts from Europe and the United States. It also includes ''hands-on'' experience in the form of 10 representative clinical case studies, which are included on the accompanying CD. As a further highlight, the latest results of the very recently introduced dual-source CT, which may soon represent the CT technology of choice for cardiac applications, are presented. This book will not only convince the reader that multi-slice cardiac CT has arrived in clinical practice, it will also make a significant contribution to the education of radiologists, cardiologists, technologists, and physicists-whether newcomers, experienced users, or researchers. (orig.)

  14. Quantification of coronary artery stenoses. Comparison of 64-slice and dual source CT angiography with cardiac catheterization

    International Nuclear Information System (INIS)

    Busch, Stephanie; Nikolaou, K.; Johnson, T.; Rist, C.; Knez, A.; Reiser, M.; Becker, C.

    2007-01-01

    Until now stenoses of the coronary arteries have been evaluated visually with CT angiography. Therefore, the results were highly dependent on subjective factors inherent in the examiner. New software tools for semiquantitative analysis (CT-QCA, quantitative coronary assessment) might be adequate to improve the diagnostic accuracy und reproducibility. CTAs of 20 patients were analyzed. Ten patients each were evaluated using 64-slice CT (64SCT) and dual source CT (DSCT) (Somatom Sensation 64 and Somatom Definition, Siemens Medical Solutions, Forchheim), respectively. Two radiologists independently evaluated the data visually and with the help of a software tool (Syngo Circulation, Siemens Medical Solutions, Forchheim). The results of the quantitative assessment of the invasive heart catheterization served as the reference standard. Sensitivity and specificity as well as the correlation coefficient, the systematic error, and the interobserver agreement (kappa) were determined. In each of both patient groups 12 stenoses were detected. For the detection of stenoses >75%, sensitivity and specificity for the visual evaluation using the 64SCT were 100% and 90%, and with the CT-QCA both were 100%. For the DSCT sensitivity and specificity were 100% for both the visual and semiautomated evaluation. The Bland-Altman plot of the results of the 64SCT showed an overestimation of 3.3% (±62.7%/56.2%) compared to the heart catheterization. The results of the DSCT exhibited an overestimation of 6.2% (±33.1%/19.8%). The interobserver agreement of the CT-QCA and the visual evaluation showed a kappa value of 0.75 and for DSCT of 1.0. The results showed a good correlation of grading stenosis between the software-assisted evaluation and the results of the coronary catheter angiography. The promising results of the DSCT are due to a superior temporal resolution compared to the 64SCT. Confirmation of these data by trials in larger patient collectives is warranted. (orig.) [de

  15. Accuracy of iodine quantification using dual energy CT in latest generation dual source and dual layer CT

    Energy Technology Data Exchange (ETDEWEB)

    Pelgrim, Gert Jan; Oudkerk, Matthijs [University of Groningen, University Medical Center Groningen, Center for Medical Imaging - North East Netherlands, P.O. Box EB44, Groningen (Netherlands); Hamersvelt, Robbert W. van; Willemink, Martin J.; Schilham, Arnold; Leiner, Tim [Utrecht University Medical Center, Department of Radiology, Utrecht (Netherlands); Schmidt, Bernhard T.; Flohr, Thomas [Siemens Healthcare GmbH, Forchheim (Germany); Milles, Julien [Philips Healthcare, Best (Netherlands); Vliegenthart, Rozemarijn [University of Groningen, University Medical Center Groningen, Center for Medical Imaging - North East Netherlands, P.O. Box EB44, Groningen (Netherlands); University of Groningen, University Medical Center Groningen, Department of Radiology, Groningen (Netherlands)

    2017-09-15

    To determine the accuracy of iodine quantification with dual energy computed tomography (DECT) in two high-end CT systems with different spectral imaging techniques. Five tubes with different iodine concentrations (0, 5, 10, 15, 20 mg/ml) were analysed in an anthropomorphic thoracic phantom. Adding two phantom rings simulated increased patient size. For third-generation dual source CT (DSCT), tube voltage combinations of 150Sn and 70, 80, 90, 100 kVp were analysed. For dual layer CT (DLCT), 120 and 140 kVp were used. Scans were repeated three times. Median normalized values and interquartile ranges (IQRs) were calculated for all kVp settings and phantom sizes. Correlation between measured and known iodine concentrations was excellent for both systems (R = 0.999-1.000, p < 0.0001). For DSCT, median measurement errors ranged from -0.5% (IQR -2.0, 2.0%) at 150Sn/70 kVp and -2.3% (IQR -4.0, -0.1%) at 150Sn/80 kVp to -4.0% (IQR -6.0, -2.8%) at 150Sn/90 kVp. For DLCT, median measurement errors ranged from -3.3% (IQR -4.9, -1.5%) at 140 kVp to -4.6% (IQR -6.0, -3.6%) at 120 kVp. Larger phantom sizes increased variability of iodine measurements (p < 0.05). Iodine concentration can be accurately quantified with state-of-the-art DECT systems from two vendors. The lowest absolute errors were found for DSCT using the 150Sn/70 kVp or 150Sn/80 kVp combinations, which was slightly more accurate than 140 kVp in DLCT. (orig.)

  16. Image quality optimization and evaluation of linearly mixed images in dual-source, dual-energy CT

    International Nuclear Information System (INIS)

    Yu Lifeng; Primak, Andrew N.; Liu Xin; McCollough, Cynthia H.

    2009-01-01

    In dual-source dual-energy CT, the images reconstructed from the low- and high-energy scans (typically at 80 and 140 kV, respectively) can be mixed together to provide a single set of non-material-specific images for the purpose of routine diagnostic interpretation. Different from the material-specific information that may be obtained from the dual-energy scan data, the mixed images are created with the purpose of providing the interpreting physician a single set of images that have an appearance similar to that in single-energy images acquired at the same total radiation dose. In this work, the authors used a phantom study to evaluate the image quality of linearly mixed images in comparison to single-energy CT images, assuming the same total radiation dose and taking into account the effect of patient size and the dose partitioning between the low-and high-energy scans. The authors first developed a method to optimize the quality of the linearly mixed images such that the single-energy image quality was compared to the best-case image quality of the dual-energy mixed images. Compared to 80 kV single-energy images for the same radiation dose, the iodine CNR in dual-energy mixed images was worse for smaller phantom sizes. However, similar noise and similar or improved iodine CNR relative to 120 kV images could be achieved for dual-energy mixed images using the same total radiation dose over a wide range of patient sizes (up to 45 cm lateral thorax dimension). Thus, for adult CT practices, which primarily use 120 kV scanning, the use of dual-energy CT for the purpose of material-specific imaging can also produce a set of non-material-specific images for routine diagnostic interpretation that are of similar or improved quality relative to single-energy 120 kV scans.

  17. Imaging of the Coronary Venous System: Validation of Three-Dimensional Rotational Venous Angiography Against Dual-Source Computed Tomography

    International Nuclear Information System (INIS)

    Knackstedt, Christian; Muehlenbruch, Georg; Mischke, Karl; Bruners, Philipp; Schimpf, Thomas; Frechen, Dirk; Schummers, Georg; Mahnken, Andreas H.; Guenther, Rolf W.; Kelm, Malte; Schauerte, Patrick

    2008-01-01

    Information on the anatomy of the cardiac venous system (CVS) is increasingly important for cardiac resynchronization therapy or percutaneous transvenous mitral valve annuloplasty. Three-dimensional (3D) imaging can further improve the understanding of the relationship of cardiac structures. This study was performed to validate the accuracy of rotational coronary sinus angiography (CSA) displaying the 3D anatomy of the CVS compared to ECG-gated, contrast-enhanced, cardiac dual-source computed tomography (DSCT). Five domestic pigs (60 kg) underwent DSCT using a standardized examination protocol. Using a standard C-arm for fluoroscopy, a rotational CSA was obtained and 3D-image reconstructions performed. Side branches were identified using both methods and enumerated. Vessel visibility was estimated for each side branch and great cardiac vein/anterior interventricular vein. Also, vessel diameters were measured at distinct landmarks, i.e., side branching. The amount of contrast medium was determined and the effective radiation exposure of both methods was calculated. There was no significant difference regarding the vessel diameter of the great cardiac vein/anterior interventricular vein or its side branches. Also, estimation of vessel visibility was not different between the two imaging modalities. Estimated radiation exposure and amount of contrast medium were lower for rotational CSA. In conclusion, a 3D reconstruction of rotational CSA images is possible. All parts of the CVS are well depicted, allowing a 3D overview of the CVS anatomy. On-site 3D visualization might improve decision making during cardiac interventions. In contrast to DSCT, rotational CSA does not demonstrate the anatomy of the mitral annulus or the course of the left circumflex artery.

  18. Intensive lipid-lowering therapy with rosuvastatin stabilizes lipid-rich coronary plaques. Evaluation using dual-source computed tomography

    International Nuclear Information System (INIS)

    Soeda, Tsunenari; Uemura, Shiro; Okayama, Satoshi

    2011-01-01

    Clinical studies using invasive modalities have reported that statin therapy stabilizes coronary plaque vulnerability. The serial changes of lipid-rich coronary plaques (LRCPs) during rosuvastatin treatment were evaluated non-invasively in patients with acute coronary syndrome (ACS) using dual-source computed tomography (DSCT). A total of 11 consecutive ACS patients, and 13 LRCPs were serially evaluated on DSCT before and 24 weeks after rosuvastatin treatment. Compared with the baseline, there was no change in post-treatment minimal lumen diameter, lumen volume, or longitudinal length of LRCPs. By contrast, the ratio of lipid core volume to plaque volume significantly decreased from 48.0±9.9% to 43.7±10.6% (P=0.04), and plaque volume decreased from 144.5±85.5 mm 3 to 119.8±78.0 mm 3 (P=0.07). The remodeling index of target LRCPs significantly decreased from 1.16±0.10 to 1.06±0.12 (P=0.02). Percent reduction of plaque volume was significantly greater in patients with a lower ratio of low-density lipoprotein to high-density lipoprotein (L/H ratio ≤1.5) at follow-up than patients with higher L/H ratio (>1.5; median -31.7% vs. -6.8%, P=0.03). Rosuvastatin therapy reduced the volume of lipid cores and LRCPs and increased the CT attenuation value of LRCPs. DSCT is an effective modality for the non-invasive evaluation of LRCPs in patients with ACS. (author)

  19. Low contrast medium-volume third-generation dual-source computed tomography angiography for transcatheter aortic valve replacement planning

    International Nuclear Information System (INIS)

    Felmly, Lloyd M.; De Cecco, Carlo N.; Varga-Szemes, Akos; McQuiston, Andrew D.; Schoepf, U.J.; Litwin, Sheldon E.; Bayer, Richard R.; Mangold, Stefanie; Vogl, Thomas J.; Wichmann, Julian L.

    2017-01-01

    To investigate feasibility, image quality and safety of low-tube-voltage, low-contrast-volume comprehensive cardiac and aortoiliac CT angiography (CTA) for planning transcatheter aortic valve replacement (TAVR). Forty consecutive TAVR candidates prospectively underwent combined CTA of the aortic root and vascular access route (270 mgI/ml iodixanol). Patients were assigned to group A (second-generation dual-source CT [DSCT], 100 kV, 60 ml contrast, 4.0 ml/s flow rate) or group B (third-generation DSCT, 70 kV, 40 ml contrast, 2.5 ml/s flow rate). Vascular attenuation, noise, signal-to-noise (SNR) and contrast-to-noise ratios (CNR) were compared. Subjective image quality was assessed by two observers. Estimated glomerular filtration (eGFR) at CTA and follow-up were measured. Besides a higher body-mass-index in group B (24.8±3.8 kg/m 2 vs. 28.1±5.4 kg/m 2 , P=0.0339), patient characteristics between groups were similar (P≥0.0922). Aortoiliac SNR (P=0.0003) was higher in group B. Cardiac SNR (P=0.0003) and CNR (P=0.0181) were higher in group A. Subjective image quality was similar (P≥0.213) except for aortoiliac image noise (4.42 vs. 4.12, P=0.0374). TAVR-planning measurements were successfully obtained in all patients. There were no significant changes in eGFR among and between groups during follow-up (P≥0.302). TAVR candidates can be safely and effectively evaluated by a comprehensive CTA protocol with low contrast volume using low-tube-voltage acquisition. (orig.)

  20. [Application of second generation dual-source computed tomography dual-energy scan mode in detecting pancreatic adenocarcinoma].

    Science.gov (United States)

    Xue, Hua-dan; Liu, Wei; Sun, Hao; Wang, Xuan; Chen, Yu; Su, Bai-yan; Sun, Zhao-yong; Chen, Fang; Jin, Zheng-yu

    2010-12-01

    To analyze the clinical value of multiple sequences derived from dual-source computed tomography (DSCT) dual-energy scan mode in detecting pancreatic adenocarcinoma. Totally 23 patients with clinically or pathologically diagnosed pancreatic cancer were enrolled in this retrospective study. DSCT (Definition Flash) was used and dual-energy scan mode was used in their pancreatic parenchyma phase scan (100kVp/230mAs and Sn140kVp/178mAs) . Mono-energetic 60kev, mono-energetic 80kev, mono-energetic 100kev, mono-energetic 120kev, linear blend image, non-linear blend image, and iodine map were acquired. pancreatic parenchyma-tumor CT value difference, ratio of tumor to pancreatic parenchyma, and pancreatic parenchyma-tumor contrast to noise ratio were calculated. One-way ANOVA was used for the comparison of diagnostic values of the above eight different dual-energy derived sequences for pancreatic cancer. The pancreatic parenchyma-tumor CT value difference, ratio of tumor to pancreatic parenchyma, and pancreatic parenchyma-tumor contrast to noise ratio were significantly different among eight sequences (P<0.05) . Mono-energetic 60kev image showed the largest parenchyma-tumor CT value [ (77.53 ± 23.42) HU] , and iodine map showed the lowest tumor/parenchyma enhancement ratio (0.39?0.12) and the largest contrast to noise ratio (4.08 ± 1.46) . Multiple sequences can be derived from dual-energy scan mode with DSCT via multiple post-processing methods. Integration of these sequences may further improve the sensitivity of the multislice spiral CT in the diagnosis of pancreatic cancer.

  1. I2S-LWR Activation Analysis of Heat Exchangers Using Hybrid Shielding Methodology with SCALE6.1

    International Nuclear Information System (INIS)

    Matijevic, M.; Pevec, D.; Jecmenica, R.

    2016-01-01

    The Integral Inherently Safe Light Water Reactor (I2S-LWR) concept developed by Georgia Tech is a novel PWR reactor delivering electric power of 1000 MWe while implementing inherent safety features typical for Generation III+ small modular reactors. The main safety feature is based on integral primary circuit configuration, bringing together compact design of the reactor core with 121 fuel assembly (FA), control rod drive mechanism (CRDM), 8 primary heat exchangers (PHE), 4 passive decay heat removal systems (DHRS), 8 pumps, and other integral components. A high power density core based on silicide fuel is selected to achieve a high thermal power which is extracted with PHEs placed in the annual region between the barrel and the vessel. The complex and integrated design of I2S-LWR leads to activation of integral components, mainly made from stainless steel, so accurate and precise Monte Carlo (MC) simulations are needed to quantify potential dose rates to personnel during routine maintenance operation. This shielding problem is therefore very challenging one, posing a non-trivial neutron flux solution in a phase space. This paper presents the performance of the hybrid shielding methodologies CADIS/FW-CADIS implemented in the MAVRIC sequence of the SCALE6.1 code package. The main objective was to develop a detailed MC shielding model of the I2S-LWR reactor along with effective variance reduction (VR) parameters and to calculate neutron fluence rates inside PHEs. Such results are then utilized to find neutron activation rate distribution via 60Co generation inside of a stack of microchannel heat exchangers (MCHX), which will be periodically withdrawn for the maintenance. 59Co impurities are the main cause of (n,gamma) radiative gamma dose to personnel via neutron activation since 60Co has half-life of 5.27 years and is emitting high energy gamma rays (1.17 MeV and 1.33 MeV). The developed MC model was successfully used to find converged fluxes inside all 8 stacks of

  2. Detection of Airway Anomalies in?Pediatric?Patients with Cardiovascular Anomalies with Low Dose Prospective ECG-Gated Dual-Source CT

    OpenAIRE

    Jiao, Hui; Xu, Zhuodong; Wu, Lebin; Cheng, Zhaoping; Ji, Xiaopeng; Zhong, Hai; Meng, Chen

    2013-01-01

    OBJECTIVES: To assess the feasibility of low-dose prospective ECG-gated dual-source CT (DSCT) in detecting airway anomalies in pediatric patients with cardiovascular anomalies compared with flexible tracheobronchoscopy (FTB). METHODS: 33 pediatrics with respiratory symptoms who had been revealed cardiovascular anomalies by transthoracic echocardiography underwent FTB and contrast material-enhanced prospective ECG-triggering CT were enrolled. The study was approved by our institution review bo...

  3. Three-dimensional balanced steady state free precession myocardial perfusion cardiovascular magnetic resonance at 3T using dual-source parallel RF transmission: initial experience.

    Science.gov (United States)

    Jogiya, Roy; Schuster, Andreas; Zaman, Arshad; Motwani, Manish; Kouwenhoven, Marc; Nagel, Eike; Kozerke, Sebastian; Plein, Sven

    2014-11-28

    The purpose of this study was to establish the feasibility of three-dimensional (3D) balanced steady-state-free-precession (bSSFP) myocardial perfusion cardiovascular magnetic resonance (CMR) at 3T using local RF shimming with dual-source RF transmission, and to compare it with spoiled gradient echo (TGRE) acquisition. Dynamic contrast-enhanced 3D bSSFP perfusion imaging was performed on a 3T MRI scanner equipped with dual-source RF transmission technology. Images were reconstructed using k-space and time broad-use linear acquisition speed-up technique (k-t BLAST) and compartment based principle component analysis (k-t PCA). In phantoms and volunteers, local RF shimming with dual source RF transmission significantly improved B1 field homogeneity compared with single source transmission (P=0.01). 3D bSSFP showed improved signal-to-noise, contrast-to-noise and signal homogeneity compared with 3D TGRE (29.8 vs 26.9, P=0.045; 23.2 vs 21.6, P=0.049; 14.9% vs 12.4%, p=0.002, respectively). Image quality was similar between bSSFP and TGRE but there were more dark rim artefacts with bSSFP. k-t PCA reconstruction reduced artefacts for both sequences compared with k-t BLAST. In a subset of five patients, both methods correctly identified those with coronary artery disease. Three-dimensional bSSFP myocardial perfusion CMR using local RF shimming with dual source parallel RF transmission at 3T is feasible and improves signal characteristics compared with TGRE. Image artefact remains an important limitation of bSSFP imaging at 3T but can be reduced with k-t PCA.

  4. Coronary calcium screening with dual-source CT: reliability of ungated, high-pitch chest CT in comparison with dedicated calcium-scoring CT

    Energy Technology Data Exchange (ETDEWEB)

    Hutt, Antoine; Faivre, Jean-Baptiste; Remy, Jacques; Remy-Jardin, Martine [CHRU et Universite de Lille, Department of Thoracic Imaging, Hospital Calmette (EA 2694), Lille (France); Duhamel, Alain; Deken, Valerie [CHRU et Universite de Lille, Department of Biostatistics (EA 2694), Lille (France); Molinari, Francesco [Centre Hospitalier General de Tourcoing, Department of Radiology, Tourcoing (France)

    2016-06-15

    To investigate the reliability of ungated, high-pitch dual-source CT for coronary artery calcium (CAC) screening. One hundred and eighty-five smokers underwent a dual-source CT examination with acquisition of two sets of images during the same session: (a) ungated, high-pitch and high-temporal resolution acquisition over the entire thorax (i.e., chest CT); (b) prospectively ECG-triggered acquisition over the cardiac cavities (i.e., cardiac CT). Sensitivity and specificity of chest CT for detecting positive CAC scores were 96.4 % and 100 %, respectively. There was excellent inter-technique agreement for determining the quantitative CAC score (ICC = 0.986). The mean difference between the two techniques was 11.27, representing 1.81 % of the average of the two techniques. The inter-technique agreement for categorizing patients into the four ranks of severity was excellent (weighted kappa = 0.95; 95 % CI 0.93-0.98). The inter-technique differences for quantitative CAC scores did not correlate with BMI (r = 0.05, p = 0.575) or heart rate (r = -0.06, p = 0.95); 87.2 % of them were explained by differences at the level of the right coronary artery (RCA: 0.8718; LAD: 0.1008; LCx: 0.0139; LM: 0.0136). Ungated, high-pitch dual-source CT is a reliable imaging mode for CAC screening in the conditions of routine chest CT examinations. (orig.)

  5. The impact of dual-source parallel radiofrequency transmission with patient-adaptive shimming on the cardiac magnetic resonance in children at 3.0 T.

    Science.gov (United States)

    Wang, Haipeng; Qiu, Liyun; Wang, Guangbin; Gao, Fei; Jia, Haipeng; Zhao, Junyu; Chen, Weibo; Wang, Cuiyan; Zhao, Bin

    2017-06-01

    The cardiac magnetic resonance (CMR) of children at 3.0 T presents a unique set of technical challenges because of their small cardiac anatomical structures, fast heart rates, and the limited ability to keep motionless and hold breathe, which could cause problems associated with field inhomogeneity and degrade the image quality. The aim of our study was to evaluate the effect of dual-source parallel radiofrequency (RF) transmission on the B1 homogeneity and image quality in children with CMR at 3.0 T. The study was approved by the institutional ethics committee and written informed consent was obtained. A total of 30 free-breathing children and 30 breath-hold children performed CMR examinations with dual-source and single-source RF transmission. The B1 homogeneity, contrast ratio (CR) of cine images, and off-resonance artifacts in cine images between dual-source and single-source RF transmission were assessed in free-breathing and breath-hold groups, respectively. In both free-breathing and breath-hold groups, higher mean percentage of flip angle (free-breathing group: 104.2 ± 4.6 vs 95.5 ± 6.3, P 3.0 T. This technology could be taken into account in CMR for children with cardiac diseases.

  6. Application of dual-source-computed tomography in pediatric cardiology in children within the first year of life; Einsatz der Dual-Source-Computertomografie in der Kinderkardiologie bei Kindern im ersten Lebensjahr

    Energy Technology Data Exchange (ETDEWEB)

    Hausmann, P.; Stenger, A.; Dittrich, S.; Gloeckler, M. [Erlangen-Nuernberg Univ., Erlangen (Germany). Pediatric Cardiology; Cesnjevar, R.; Rueffer, A. [Erlangen-Nuernberg Univ., Erlangen (Germany). Congenital Heart Surgery; Hammon, M.; Uder, M.; Rompel, O. [Erlangen-Nuernberg Univ., Erlangen (Germany). Radiology

    2016-02-15

    To assess fields of application and value of dual source computed tomography (DSCT) for diagnostics and therapy in patients with congenital heart disease during their first year of life. Evaluation of image quality, surgical use and radiation exposure of 2nd and 3rd generation DSCT. DSCT was applied in 118 cases between January 2012 and October 2014 for diagnostics of congenital heart defects. 2nd generation was used in 91 cases until April 2014 and 3rd generation in 27 cases during the period thereafter. 3D reconstructions of the image data were created for clinical diagnostics and planning of interventions. Image quality was assessed using a 4-point-scale. The visibility of the mammary arteries was analyzed, and signal-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR) were calculated. The usefulness of 3D-reconstructions for surgical planning was rated using a 5-point-scale. Radiation exposure and contrast dye consumption were determined. All cases were analyzed retrospectively. DSCT was successfully used in 118 cases. All image data obtained were interpretable. More than 60 percent of cases did not show any artifacts. The mammary arteries were visible down to the diaphragmatic arch in more than 80 percent of cases. Diagnostic value and surgical benefit were evaluated as ''useful'' or as ''essential'' in all cases. Median radiation dose was 0.4 mSv and 0.27 mSv for the 2nd and 3rd generation DSCT, respectively. Consumption of contrast dye was 2 ml/kg in all cases. DSCT is a modern and extremely helpful technique for diagnostics and planning of interventions in patients with complex congenital heart defects. Extracardiac vascular structures in particular can be depicted three-dimensionally at high resolution. The use of iterative reconstruction with 3rd generation DSCT yielded image quality similar to that of 2nd generation DSCT at considerably reduced radiation exposure level compared to 2nd generation DSCT. 3rd

  7. Low tube voltage dual source computed tomography to reduce contrast media doses in adult abdomen examinations: A phantom study

    Energy Technology Data Exchange (ETDEWEB)

    Thor, Daniel [Department of Diagnostic Medical Physics, Karolinska University Hospital, Stockholm 14186 (Sweden); Brismar, Torkel B., E-mail: torkel.brismar@gmail.com; Fischer, Michael A. [Department of Clinical Science, Intervention and Technology at Karolinska Institutet and Department of Radiology, Karolinska University Hospital in Huddinge, Stockholm 14186 (Sweden)

    2015-09-15

    Purpose: To evaluate the potential of low tube voltage dual source (DS) single energy (SE) and dual energy (DE) computed tomography (CT) to reduce contrast media (CM) dose in adult abdominal examinations of various sizes while maintaining soft tissue and iodine contrast-to-noise ratio (CNR). Methods: Four abdominal phantoms simulating a body mass index of 16 to 35 kg/m{sup 2} with four inserted syringes of 0, 2, 4, and 8 mgI/ml CM were scanned using a 64-slice DS-CT scanner. Six imaging protocols were used; one single source (SS) reference protocol (120 kV, 180 reference mAs), four low kV SE protocols (70 and 80 kV using both SS and DS), and one DE protocol at 80/140 kV. Potential CM reduction with unchanged CNRs relative to the 120 kV protocol was calculated along with the corresponding increase in radiation dose. Results: The potential contrast media reductions were determined to be approximately 53% for DS 70 kV, 51% for SS 70 kV, 44% for DS 80 kV, 40% for SS 80 kV, and 20% for DE (all differences were significant, P < 0.05). Constant CNR could be achieved by using DS 70 kV for small to medium phantom sizes (16–26 kg/m{sup 2}) and for all sizes (16–35 kg/m{sup 2}) when using DS 80 kV and DE. Corresponding radiation doses increased by 60%–107%, 23%–83%, and 6%–12%, respectively. Conclusions: DS single energy CT can be used to reduce CM dose by 44%–53% with maintained CNR in adult abdominal examinations at the cost of an increased radiation dose. DS dual-energy CT allows reduction of CM dose by 20% at similar radiation dose as compared to a standard 120 kV single source.

  8. Quantitative assessment of left ventricular function with dual-source CT in comparison to cardiac magnetic resonance imaging: initial findings

    Energy Technology Data Exchange (ETDEWEB)

    Busch, S.; Johnson, T.R.C.; Wintersperger, B.J.; Minaifar, N.; Bhargava, A.; Rist, C.; Reiser, M.F.; Becker, C.; Nikolaou, K. [University of Munich, Department of Clinical Radiology, Munich (Germany)

    2008-03-15

    Cardiac magnetic resonance imaging and echocardiography are currently regarded as standard modalities for the quantification of left ventricular volumes and ejection fraction. With the recent introduction of dual-source computedtomography (DSCT), the increased temporal resolution of 83 ms should also improve the assessment of cardiac function in CT. The aim of this study was to evaluate the accuracy of DSCT in the assessment of left ventricular functional parameters with cardiac magnetic resonance imaging (MRI) as standard of reference. Fifteen patients (two female, 13 male; mean age 50.8 {+-} 19.2 years) underwent CT and MRI examinations on a DSCT (Somatom Definition; Siemens Medical Solutions, Forchheim, Germany) and a 3.0-Tesla MR scanner (Magnetom Trio; Siemens Medical Solutions), respectively. Multiphase axial CT images were analysed with a semiautomatic region growing algorithms (Syngo Circulation; Siemens Medical Solutions) by two independent blinded observers. In MRI, dynamic cine loops of short axis slices were evaluated with semiautomatic contour detection software (ARGUS; Siemens Medical Solutions) independently by two readers. End-systolic volume (ESV), end-diastolic volume (EDV), ejection fraction (EF) and stroke volume (SV) were determined for both modalities, and correlation coefficient, systematic error, limits of agreement and inter-observer variability were assessed. In DSCT, EDV and ESV were 135.8 {+-} 41.9 ml and 54.9 {+-} 29.6 ml, respectively, compared with 132.1 {+-} 40.8 ml EDV and 57.6 {+-} 27.3 ml ESV in MRI. Thus, EDV was overestimated by 3.7 ml (limits of agreement -46.1/+53.6), while ESV was underestimated by 2.6 ml (-36.6/+31.4). Mean EF was 61.6 {+-} 12.4% in DSCT and 57.9 {+-} 9.0% in MRI, resulting in an overestimation of EF by 3.8% with limits of agreement at -14.7 and +22.2%. Rank correlation rho values were 0.81 for EDV (P = 0.0024), 0.79 for ESV (P = 0.0031) and 0.64 for EF (P = 0.0168). The kappa value of inter

  9. The impact of heart rate on image quality and reconstruction timing of dual-source CT coronary angiography

    International Nuclear Information System (INIS)

    Wang Yining; Jin Zhengyu; Kong Lingyan; Zhang Zhuhua; Song Lan; Mu Wenbin; Wang Yun; Zhao Wenmin; Zhang Shuyang; Lin Songbai

    2008-01-01

    Objective: To evaluate the impact of patient's heart rate (HR) on coronary CT angiography (CTA) image quality (IQ) and reconstruction timing in dual-source CT (DSCT). Methods Ninety-five patients with suspicion of coronary artery disease were examined with a DSCT scanner (Somatom Definition, Siemens) using 32 x 0.6 mm collimation. All patients were divided three groups according to the heart rate (HR): group 1, HR ≤ 70 beats per minute (bpm), n=26; group 2, HR >70 bpm to ≤90 bpm, n=37; group 3, HR > 90 bpm, n=32. No beta-blockers were taken before CT scan. 50- 60 ml of nonionic contrast agent were injected with a rate of 5 ml/s. Images were reconstructed from 10% to 100% of the R-R interval using single-segment reconstruction. Two readers independently assessed IQ of all coronary, segments using a 3-point scale from excellent (1) to non-assessable (3) for coronary segments and the relationship between IQ and the HR. Results: Overall mean IQ score was 1.31 ± 0.55 for all patients with 1.08 ± 0.27 for group 1, 1.32 ± 0.58 for group 2 and 1.47 ± 0.61 for group 3. The IQ was better in the LAD than the RCA and LCX (P<0.01). Only 1.4% (19/1386) of coronary artery segments were considered non-assessable due to the motion artifacts. Optimal image quality of all coronary segments in 74 patients (77.9%) can be achieved with one reconstruction data set. The best IQ was predominately in diastole (88.5%) in group 1, while the best IQ was in systole (84.4%) in group 3. Conclusions: DSCT can achieve the optimal IQ with a wide range of HR using single-segment reconstruction. With the increasing of HR, the timing of data reconstruction for the best IQ shifts from mid-diastole to systole. (authors)

  10. Image quality and absorbed dose comparison of single- and dual-source cone-beam computed tomography.

    Science.gov (United States)

    Miura, Hideharu; Ozawa, Shuichi; Okazue, Toshiya; Kawakubo, Atsushi; Yamada, Kiyoshi; Nagata, Yasushi

    2018-04-17

    Dual-source cone-beam computed tomography (DCBCT) is currently available in the Vero4DRT image-guided radiotherapy system. We evaluated the image quality and absorbed dose for DCBCT and compared the values with those for single-source CBCT (SCBCT). Image uniformity, Hounsfield unit (HU) linearity, image contrast, and spatial resolution were evaluated using a Catphan phantom. The rotation angle for acquiring SCBCT and DCBCT images is 215° and 115°, respectively. The image uniformity was calculated using measurements obtained at the center and four peripheral positions. The HUs of seven materials inserted into the phantom were measured to evaluate HU linearity and image contrast. The Catphan phantom was scanned with a conventional CT scanner to measure the reference HU for each material. The spatial resolution was calculated using high-resolution pattern modules. Image quality was analyzed using ImageJ software ver. 1.49. The absorbed dose was measured using a 0.6-cm 3 ionization chamber with a 16-cm-diameter cylindrical phantom, at the center and four peripheral positions of the phantom, and calculated using weighted cone-beam CT dose index (CBCTDI w ). Compared with that of SCBCT, the image uniformity of DCBCT was slightly reduced. A strong linear correlation existed between the measured HU for DCBCT and the reference HU, although the linear regression slope was different from that of the reference HU. DCBCT had poorer image contrast than did SCBCT, particularly with a high-contrast material. There was no significant difference between the spatial resolutions of SCBCT and DCBCT. The absorbed dose for DCBCT was higher than that for SCBCT, because in DCBCT, the two x-ray projections overlap between 45° and 70°. We found that the image quality was poorer and the absorbed dose was higher for DCBCT than for SCBCT in the Vero4DRT. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of

  11. Quantitative assessment of left ventricular function with dual-source CT in comparison to cardiac magnetic resonance imaging: initial findings

    International Nuclear Information System (INIS)

    Busch, S.; Johnson, T.R.C.; Wintersperger, B.J.; Minaifar, N.; Bhargava, A.; Rist, C.; Reiser, M.F.; Becker, C.; Nikolaou, K.

    2008-01-01

    Cardiac magnetic resonance imaging and echocardiography are currently regarded as standard modalities for the quantification of left ventricular volumes and ejection fraction. With the recent introduction of dual-source computedtomography (DSCT), the increased temporal resolution of 83 ms should also improve the assessment of cardiac function in CT. The aim of this study was to evaluate the accuracy of DSCT in the assessment of left ventricular functional parameters with cardiac magnetic resonance imaging (MRI) as standard of reference. Fifteen patients (two female, 13 male; mean age 50.8 ± 19.2 years) underwent CT and MRI examinations on a DSCT (Somatom Definition; Siemens Medical Solutions, Forchheim, Germany) and a 3.0-Tesla MR scanner (Magnetom Trio; Siemens Medical Solutions), respectively. Multiphase axial CT images were analysed with a semiautomatic region growing algorithms (Syngo Circulation; Siemens Medical Solutions) by two independent blinded observers. In MRI, dynamic cine loops of short axis slices were evaluated with semiautomatic contour detection software (ARGUS; Siemens Medical Solutions) independently by two readers. End-systolic volume (ESV), end-diastolic volume (EDV), ejection fraction (EF) and stroke volume (SV) were determined for both modalities, and correlation coefficient, systematic error, limits of agreement and inter-observer variability were assessed. In DSCT, EDV and ESV were 135.8 ± 41.9 ml and 54.9 ± 29.6 ml, respectively, compared with 132.1 ± 40.8 ml EDV and 57.6 ± 27.3 ml ESV in MRI. Thus, EDV was overestimated by 3.7 ml (limits of agreement -46.1/+53.6), while ESV was underestimated by 2.6 ml (-36.6/+31.4). Mean EF was 61.6 ± 12.4% in DSCT and 57.9 ± 9.0% in MRI, resulting in an overestimation of EF by 3.8% with limits of agreement at -14.7 and +22.2%. Rank correlation rho values were 0.81 for EDV (P = 0.0024), 0.79 for ESV (P 0.0031) and 0.64 for EF (P = 0.0168). The kappa value of inter-observer variability were

  12. Evaluation of radiation dose in chest scan with enhanced dual-source computed tomography in children with congenital heart disease

    International Nuclear Information System (INIS)

    Hou Zhihui; Lu Bin; Tang Xiang; Han Lei

    2011-01-01

    Objective: To evaluate the radiation dose from enhanced dual-source computed Tomography (DSCT) scan on children with congenital heart disease (CHD). Methods: Seventy children with CHD, age from 1 month to 8 years old, were scanned with enhanced DSCT. Children were divided by age into 5 years old group. The differences among three groups were tested by F test. Then, the SNK test was used to compare the difference between each group. Multiple linear regression analysis was used to test the relationship of dose length product (DLP) with the age, weight, voltage, current, pitch and scan sheet. Results: The average value of DLP was (144.46± 74.07) mGy·cm for all the 70 cases, and that of effective does (ED) was (4.68±2.34) mSv. There were significant differences of DLP among the 3 groups [ 5 years (208.00±73.87) mGy · cm, F=8.26, P=0.0009]. The SNK test showed statistical differences of DLP between 5 years old group (q=5.21, 6.52, P=0.009, 0.004). The difference of DLP between 1-5 years old group and > 5 years old group did not reach significant (q=0.28, P=0.48). The differences of ED was not statistically significant among the three groups [ 5 years (3.74±1.33) mSv, F=0.54, P=0.59]. DLP was positively correlated with age (4.3 years, r=0.54186, P=0.0008), weight (12.1 kg, r=0.56371, P=0.0004), voltage [(95.48±6.99) kV, r=0.63269, P<0.01], current [(138.55±40.67) mA, r=0.79608, P< 0.0001] and scan sheet (236.10±46.51, r=0.72192, P<0.01). DLP was negative correlated with pitch (0.48±0.03, r=-0.46693, P=0.0047). Conclusion: Higher DLP was observed in children over 1 year old under enhanced DSCT scan, but ED was not statistically significant among the three groups due to the higher K value in the children under 1 year old. (authors)

  13. Assessment of regional left ventricular function by Dual Source Computed Tomography: Interobserver variability and validation to laevocardiography

    Energy Technology Data Exchange (ETDEWEB)

    Pflederer, T. [Department of Internal Medicine 2 (Cardiology), University of Erlangen (Germany)], E-mail: tobiaspflederer@web.de; Ho, K.T. [Department of Cardiology, Tan Tock Seng Hospital (Singapore)], E-mail: contact@ttsh.com.sg; Anger, T. [Department of Internal Medicine 2 (Cardiology), University of Erlangen (Germany)], E-mail: thomas.anger@uk-erlangen.de; Kraehner, R. [Department of Internal Medicine 2 (Cardiology), University of Erlangen (Germany)], E-mail: robert.kraehner@uk-erlangen.de; Ropers, D. [Department of Internal Medicine 2 (Cardiology), University of Erlangen (Germany)], E-mail: dieter.ropers@uk-erlangen.de; Muschiol, G. [Department of Internal Medicine 2 (Cardiology), University of Erlangen (Germany)], E-mail: gerd.muschiol@uk-erlangen.de; Renz, A. [Department of Internal Medicine 2 (Cardiology), University of Erlangen (Germany)], E-mail: alexandra.renz@uk-erlangen.de; Daniel, W.G. [Department of Internal Medicine 2 (Cardiology), University of Erlangen (Germany)], E-mail: werner.daniel@uk-erlangen.de; Achenbach, S. [Department of Internal Medicine 2 (Cardiology), University of Erlangen (Germany)], E-mail: stephan.achenbach@uk-erlangen.de

    2009-10-15

    Objective: Assessment of left ventricular function is possible in contrast-enhanced cardiac CT data sets. However, rapid ventricular motion especially in systole can lead to artifacts. Dual Source Computed Tomography (DSCT) has high temporal resolution which effectively limits motion artifact. We therefore assessed the accuracy of DSCT to detect regional left ventricular wall motion abnormalities in comparison to invasive cine angiocardiography. Methods: We analyzed DSCT data sets of 50 patients (39 male, 11 female, mean age: 61 {+-} 10 years) which were acquired after intravenous injection of 55-70 mL contrast agent (rotation time: 330 ms, collimation: 2 mm x 64 mm x 0.6 mm, 120 kV, 380 mAs, ECG-correlated tube current modulation). 10 data sets consisting of transaxial slices with a slice thickness of 1.5 mm, an increment of 1.0 mm and a matrix of 256 x 256 pixels were reconstructed at 10 time instants during the cardiac cycle (0-90% in 10% increments). The data sets were analyzed visually by two independent readers, using standard left ventricular planes, concerning regional wall motion abnormalities. DSCT was verified in a blinded fashion against cine ventriculography performed during cardiac catheterization (RAO and LAO projection), using a 7-segment model. Analysis was performed on a per-patient (presence of at least one hypo-, a- or dyskinetic segment) and on a per-segment basis. Results: Concerning the presence of a wall motion abnormality, the two observers agreed in 340/350 segments (97%) and 48/50 patients (96%). In invasive cine angiocardiography, 22 of 50 patients displayed at least one segment with abnormal contraction. To detect these patients, DSCT showed a sensitivity of 95% (21/22), specificity of 96% (27/28), positive predictive value of 95% and negative predictive value of 96%. Out of a total of 350 left ventricular segments, 66 segments had abnormal contraction in cine angiocardiography (34 hypokinetic, 26 akinetic, 6 dyskinetic). For detection

  14. Hybrid pressure retarded osmosis-membrane distillation system for power generation from low-grade heat: thermodynamic analysis and energy efficiency.

    Science.gov (United States)

    Lin, Shihong; Yip, Ngai Yin; Cath, Tzahi Y; Osuji, Chinedum O; Elimelech, Menachem

    2014-05-06

    We present a novel hybrid membrane system that operates as a heat engine capable of utilizing low-grade thermal energy, which is not readily recoverable with existing technologies. The closed-loop system combines membrane distillation (MD), which generates concentrated and pure water streams by thermal separation, and pressure retarded osmosis (PRO), which converts the energy of mixing to electricity by a hydro-turbine. The PRO-MD system was modeled by coupling the mass and energy flows between the thermal separation (MD) and power generation (PRO) stages for heat source temperatures ranging from 40 to 80 °C and working concentrations of 1.0, 2.0, and 4.0 mol/kg NaCl. The factors controlling the energy efficiency of the heat engine were evaluated for both limited and unlimited mass and heat transfer kinetics in the thermal separation stage. In both cases, the relative flow rate between the MD permeate (distillate) and feed streams is identified as an important operation parameter. There is an optimal relative flow rate that maximizes the overall energy efficiency of the PRO-MD system for given working temperatures and concentration. In the case of unlimited mass and heat transfer kinetics, the energy efficiency of the system can be analytically determined based on thermodynamics. Our assessment indicates that the hybrid PRO-MD system can theoretically achieve an energy efficiency of 9.8% (81.6% of the Carnot efficiency) with hot and cold working temperatures of 60 and 20 °C, respectively, and a working solution of 1.0 M NaCl. When mass and heat transfer kinetics are limited, conditions that more closely represent actual operations, the practical energy efficiency will be lower than the theoretically achievable efficiency. In such practical operations, utilizing a higher working concentration will yield greater energy efficiency. Overall, our study demonstrates the theoretical viability of the PRO-MD system and identifies the key factors for performance

  15. Hybrid PV and solar-thermal systems for domestic heat and power provision in the UK: Techno-economic considerations

    International Nuclear Information System (INIS)

    Herrando, María; Markides, Christos N.

    2016-01-01

    Highlights: • Renewable heat and power generation in UK homes with PVT systems studied. • PVT/w generation: 2.3 MW_e h/yr (51% of demand) and 1.0 MW_t_h h/yr (36% hot water). • Optimised PVT/w system has 9–11 year payback periods (PV-only: 6.8 years). • Same system allows 16.0-t CO_2 reduction and 14-t primary fossil-fuel saving. • With a ∼2:1 support (£/W_e h:£/W_t_h h), PVT and PV have similar payback periods. - Abstract: A techno-economic analysis is undertaken to assess hybrid PV/solar-thermal (PVT) systems for distributed electricity and hot-water provision in a typical house in London, UK. In earlier work (Herrando et al., 2014), a system model based on a PVT collector with water as the cooling medium (PVT/w) was used to estimate average year-long system performance. The results showed that for low solar irradiance levels and low ambient temperatures, such as those associated with the UK climate, a higher coverage of total household energy demands and higher CO_2 emission savings can be achieved by the complete coverage of the solar collector with PV and a relatively low collector cooling flow-rate. Such a PVT/w system demonstrated an annual electricity generation of 2.3 MW h, or a 51% coverage of the household’s electrical demand (compared to an equivalent PV-only value of 49%), plus a significant annual water heating potential of to 1.0 MW h, or a 36% coverage of the hot-water demand. In addition, this system allowed for a reduction in CO_2 emissions amounting to 16.0 tonnes over a life-time of 20 years due to the reduction in electrical power drawn from the grid and gas taken from the mains for water heating, and a 14-tonne corresponding displacement of primary fossil-fuel consumption. Both the emissions and fossil-fuel consumption reductions are significantly larger (by 36% and 18%, respectively) than those achieved by an equivalent PV-only system with the same peak rating/installed capacity. The present paper proceeds further, by

  16. Performance of hybrid quad generation system consisting of solid oxide fuel cell system and absorption heat pump

    DEFF Research Database (Denmark)

    Cachorro, Irene Albacete; Daraban, Iulia Maria; Lainé, Guillaume

    2013-01-01

    . The heat pump is a heat driven system and is running with the heat recovered by a heat exchanger from the exhausted gases from SOFC. The working fluid pair is NH3-H2O and is driven in two evaporators which are working at two different pressures. Thus, the heat pump will operate at tree pressure level...... with natural gas. The natural gas is first converted to a mixture of H2 and CO which feed the anode after a preheating step. The cathode is supplied with preheated air and gives, as output, electrical energy. The anode output is the exhaust gas which represents the thermal energy reservoir for heating...

  17. Role of direct covalent bonding in enhanced heat dissipation property of flexible graphene oxide–carbon nanotube hybrid film

    International Nuclear Information System (INIS)

    Hwang, Yongseon; Kim, Myeongjin; Kim, Jooheon

    2013-01-01

    The thermal conductivity of graphene oxide/multiwalled carbon nanotube (GO/MWCNT) hybrid films with and without covalent bonding is examined in this study. To fabricate chemically bonded GO/MWCNT hybrid films, chlorinated GO and amino-functionalized MWCNTs are bonded covalently. The mixtures of surface modified GO and MWCNT were filtered and then subjected to hot pressing to fabricate stacked films. Examination of these chemically bonded hybrid films reveal that chlorine-doped GO exhibits enhanced electrical properties because it creates hole charge carriers by attracting the electrons in GO towards chlorine. Enhanced electrical conductivity and low sheet resistance are observed also with increasing MWCNT loadings. On comparing the through-plane thermal properties, the chemically bonded hybrid films were found to exhibit higher thermal conductivity than do the physically bonded hybrid films because of the synergetic interaction of functional groups in GO and MWCNTs in the former films. However, excess addition of MWCNTs to the films leads to an increasing phonon scattering density and a decreased thermal conductivity. - Highlights: • Graphene oxide/carbon nanotube (GO/CNT) films are bonded covalently. • GO/CNT hybrid films are prepared through filtering and hot-pressing method. • Chemically bonded hybrid films exhibit enhanced electrical and thermal properties. • Enhanced thermal conductivity is explained according to increasing CNT contents

  18. Dual-source CT coronary angiography in patients with atrial fibrillation: Comparison with single-source CT

    International Nuclear Information System (INIS)

    Wang Yining; Zhang Zhuhua; Kong Lingyan; Song Lan; Merges, Reto D.; Chen Jiuhong; Jin Zhengyu

    2008-01-01

    Objective: To evaluate the performance of dual-source computed tomography (DSCT) for the visualization of the coronary arteries in a population with atrial fibrillation (AF) compared to single-source CT (SSCT) and to explore the impact of patients' heart rate (HR) on image quality (IQ) and reconstruction timing. Methods: Thirty consecutive patients (11 male, 19 female; 69.0 ± 9.2 years old) with suspected coronary artery disease and permanent AF were examined on a DSCT scanner (120 kV, 400 mAs/rot, 0.33 s rotation time, 64 x 0.6 mm collimation, pitch 0.20-0.28, Siemens Somatom Definition). Patients were divided into two groups: low and medium HR group (HR ≤ 80 bpm, n = 14) and high HR group (HR > 80 bpm, n = 16). Five of the patients also underwent conventional coronary angiography (CAG). The raw data from both tube detector arrays were reconstructed as DSCT data using a routine algorithm (temporal resolution of 83 ms). The raw data from one tube detector array was reconstructed separately on the same system using a routine single source algorithm (temporal resolution of 83-165 ms) and defined as virtual SSCT data. Image quality was assessed using a four-point grading scale from excellent (1) to non-assessable (4). Results: IQ of the DSCT data was significantly better than that of the virtual SSCT data (mean score 1.33 ± 0.61 vs. 1.80 ± 1.02; Z = -8.755, P = 0.000). 98.6% of the segments shown in DSCT were diagnostic, compared with 89.9% of the segments in virtual SSCT, χ 2 = 32.595, P = 0.000. In DSCT group, IQ of low HR group was also better than that of high HR group, although the difference was not as big (mean score 1.25 ± 0.52 vs. 1.38 ± 0.66; Z = -2.227, P = 0.026). The mean HR of low HR group and high HR group were 67.4 ± 8.5 beats per minute (bpm) and 94.2 ± 8.8 bpm (t = -8.499, P = 0.000). The range of the variation of HR was higher in high HR group than in low HR group (mean difference between maximum and minimum HR 79.5 ± 21.0 vs. 49.9 ± 21

  19. Dual-source CT coronary angiography in patients with atrial fibrillation: Comparison with single-source CT

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yining [Department of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing (China)], E-mail: yiningpumc@hotmail.com; Zhang Zhuhua [Department of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing (China)], E-mail: yiningpumc@sina.com; Kong Lingyan [Department of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing (China)], E-mail: klyan78@hotmail.com; Song Lan [Department of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing (China)], E-mail: sallysonglan@sina.com; Merges, Reto D. [CT Research Collaboration, Siemens Ltd. (China)], E-mail: reto.merges@siemens.com; Chen Jiuhong [CT Research Collaboration, Siemens Ltd. (China)], E-mail: jiuhong.chen@siemens.com; Jin Zhengyu [Department of Radiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing (China)], E-mail: jin_zhengyu@sina.com

    2008-12-15

    Objective: To evaluate the performance of dual-source computed tomography (DSCT) for the visualization of the coronary arteries in a population with atrial fibrillation (AF) compared to single-source CT (SSCT) and to explore the impact of patients' heart rate (HR) on image quality (IQ) and reconstruction timing. Methods: Thirty consecutive patients (11 male, 19 female; 69.0 {+-} 9.2 years old) with suspected coronary artery disease and permanent AF were examined on a DSCT scanner (120 kV, 400 mAs/rot, 0.33 s rotation time, 64 x 0.6 mm collimation, pitch 0.20-0.28, Siemens Somatom Definition). Patients were divided into two groups: low and medium HR group (HR {<=} 80 bpm, n = 14) and high HR group (HR > 80 bpm, n = 16). Five of the patients also underwent conventional coronary angiography (CAG). The raw data from both tube detector arrays were reconstructed as DSCT data using a routine algorithm (temporal resolution of 83 ms). The raw data from one tube detector array was reconstructed separately on the same system using a routine single source algorithm (temporal resolution of 83-165 ms) and defined as virtual SSCT data. Image quality was assessed using a four-point grading scale from excellent (1) to non-assessable (4). Results: IQ of the DSCT data was significantly better than that of the virtual SSCT data (mean score 1.33 {+-} 0.61 vs. 1.80 {+-} 1.02; Z = -8.755, P = 0.000). 98.6% of the segments shown in DSCT were diagnostic, compared with 89.9% of the segments in virtual SSCT, {chi}{sup 2} = 32.595, P = 0.000. In DSCT group, IQ of low HR group was also better than that of high HR group, although the difference was not as big (mean score 1.25 {+-} 0.52 vs. 1.38 {+-} 0.66; Z = -2.227, P = 0.026). The mean HR of low HR group and high HR group were 67.4 {+-} 8.5 beats per minute (bpm) and 94.2 {+-} 8.8 bpm (t = -8.499, P = 0.000). The range of the variation of HR was higher in high HR group than in low HR group (mean difference between maximum and minimum HR

  20. Assessment of global left ventricular function with dual-source computed tomography in patients with valvular heart disease

    Energy Technology Data Exchange (ETDEWEB)

    Bak, So Hyeon; Jeon, Hae Jeong (Dept. of Radiology, Konkuk Univ. Hospital, Konkuk Univ. School of Medicine, Seoul (Korea, Republic of)); Ko, Sung Min (Dept. of Radiology, Konkuk Univ. Hospital, Konkuk Univ. School of Medicine, Seoul (Korea, Republic of); Research Inst. of Medical Science, Konkuk Univ. Hospital, Konkuk Univ. School of Medicine, Seoul (Korea, Republic of)), Email: 20070437@kuh.ac.kr; Yang, Hyun Suk; Hwang, Hweung Kon (Dept. of Cardiology, Konkuk Univ. Hospital, Konkuk Univ. School of Medicine, Seoul (Korea, Republic of)); Song, Meong Gun (Dept. of Thoracic Surgery, Konkuk Univ. Hospital, Konkuk Univ. School of Medicine, Seoul (Korea, Republic of))

    2012-04-15

    Background: Left ventricular (LV) function is a vital parameter for prognosis, therapy guidance, and follow-up of cardiovascular disease. Dual-source computed tomography (DSCT) provides an accurate analysis of global LV function. Purpose: To assess the performance of DSCT in the determination of global LV functional parameters in comparison with cardiovascular magnetic resonance (CMR) and two-dimensional transthoracic echocardiography (2D-TTE) in patients with valvular heart disease (VHD). Material and Methods: A total of 111 patients (58 men, mean age 49.9 years) with known VHD and who underwent DSCT, 2D-TTE, and CMR a period of 2 weeks before undergoing valve surgery were included in this study. LV end-systolic volume (ESV), end-diastolic volume (EDV), stroke volume (SV), and ejection fraction (EF) were calculated by DSCT using the threshold-based technique, by 2D-TTE using a modified Simpson's method, and by CMR using Simpson's method. Agreement for parameters of LV global function was determined with the Pearson's correlation coefficient (r) and Bland-Altman analysis. All the DSCT and CMR data-sets were assessed independently by two readers. Results: Fifty of the total 111 patients had aortic VHD, 29 patients had mitral VHD, and 32 patients had mixed aortic and mitral VHD. An excellent inter-observer agreement was seen for the assessment of global LV function using DSCT (r 0.910-0.983) and CMR (r = 0.854-0.965). An excellent or good correlation (r 0.93, 0.95, 0.87, and 0.71, respectively, P < 0.001) was noted between the DSCT and 2D-TTE values for EDV, ESV, SV, and EF. EDV (33.7 mL, P < 0.001), ESV (12.1 mL, P < 0.001), SV (21.2 mL, P < 0.001), and EF (1.6%, P = 0.019) were significantly overestimated by DSCT when compared with 2D-TTE. An excellent correlation (r = 0.96, 0.97, 0.91, and 0.94, respectively, P < 0.001) between DSCT and CMR was seen in the evaluation of EDV, ESV, SV, and EF. EDV (15.9 mL, P < 0.001), ESV (7.3 mL, P < 0.001), and SV

  1. Assessment of global left ventricular function with dual-source computed tomography in patients with valvular heart disease

    International Nuclear Information System (INIS)

    Bak, So Hyeon; Jeon, Hae Jeong; Ko, Sung Min; Yang, Hyun Suk; Hwang, Hweung Kon; Song, Meong Gun

    2012-01-01

    Background: Left ventricular (LV) function is a vital parameter for prognosis, therapy guidance, and follow-up of cardiovascular disease. Dual-source computed tomography (DSCT) provides an accurate analysis of global LV function. Purpose: To assess the performance of DSCT in the determination of global LV functional parameters in comparison with cardiovascular magnetic resonance (CMR) and two-dimensional transthoracic echocardiography (2D-TTE) in patients with valvular heart disease (VHD). Material and Methods: A total of 111 patients (58 men, mean age 49.9 years) with known VHD and who underwent DSCT, 2D-TTE, and CMR a period of 2 weeks before undergoing valve surgery were included in this study. LV end-systolic volume (ESV), end-diastolic volume (EDV), stroke volume (SV), and ejection fraction (EF) were calculated by DSCT using the threshold-based technique, by 2D-TTE using a modified Simpson's method, and by CMR using Simpson's method. Agreement for parameters of LV global function was determined with the Pearson's correlation coefficient (r) and Bland-Altman analysis. All the DSCT and CMR data-sets were assessed independently by two readers. Results: Fifty of the total 111 patients had aortic VHD, 29 patients had mitral VHD, and 32 patients had mixed aortic and mitral VHD. An excellent inter-observer agreement was seen for the assessment of global LV function using DSCT (r 0.910-0.983) and CMR (r = 0.854-0.965). An excellent or good correlation (r 0.93, 0.95, 0.87, and 0.71, respectively, P < 0.001) was noted between the DSCT and 2D-TTE values for EDV, ESV, SV, and EF. EDV (33.7 mL, P < 0.001), ESV (12.1 mL, P < 0.001), SV (21.2 mL, P < 0.001), and EF (1.6%, P = 0.019) were significantly overestimated by DSCT when compared with 2D-TTE. An excellent correlation (r = 0.96, 0.97, 0.91, and 0.94, respectively, P < 0.001) between DSCT and CMR was seen in the evaluation of EDV, ESV, SV, and EF. EDV (15.9 mL, P < 0.001), ESV (7.3 mL, P < 0.001), and SV (8.5 mL, P < 0

  2. Identification of coronary artery anatomy on dual-source cardiac computed tomography before arterial switch operation in newborns and young infants. Comparison with transthoracic echocardiography

    Energy Technology Data Exchange (ETDEWEB)

    Goo, Hyun Woo [University of Ulsan College of Medicine, Asan Medical Center, Department of Radiology and Research Institute of Radiology, Seoul (Korea, Republic of)

    2018-02-15

    Considering inherent limitations of transthoracic echocardiography, the diagnostic accuracy of cardiac CT in identifying coronary artery anatomy before arterial switch operation needs to be investigated with recently improved coronary artery visibility using electrocardiogram (ECG)-synchronized dual-source CT. To compare diagnostic accuracy between cardiac CT using a dual-source scanner and transthoracic echocardiography in identifying coronary artery anatomy before arterial switch operation in newborns and young infants. The study included 101 infants (median age 4 days, range 0 days to 10 months; M:F=78:23) who underwent ECG-synchronized cardiac dual-source CT and transthoracic echocardiography before arterial switch operation between July 2011 and December 2016. We evaluated and classified coronary artery anatomy on cardiac CT and transthoracic echocardiography. With the surgical findings as the reference standard, we compared the diagnostic accuracy for identifying coronary artery anatomy between cardiac CT and transthoracic echocardiography. The most common coronary artery pattern was the usual pattern (left coronary artery from sinus 1 and right coronary artery from sinus 2; 64.4%, 65/101), followed by a single coronary artery from sinus 2 and a conal branch from sinus 1 (7.9%, 8/101), the inverted pattern (5.9%, 6/101), the right coronary artery and left anterior descending artery from sinus 1 and the left circumflex artery from sinus 2 (5.9%, 6/101), and others. In 96 infants with surgically proven coronary artery anatomy, the diagnostic accuracy of cardiac CT was significantly higher than that of transthoracic echocardiography (91.7%, 88/96 vs. 54.2%, 52/96; P<0.0001). Diagnostic accuracy of cardiac CT is significantly higher than that of echocardiography in identifying coronary artery anatomy before arterial switch operation in newborns and young infants. (orig.)

  3. Identification of coronary artery anatomy on dual-source cardiac computed tomography before arterial switch operation in newborns and young infants. Comparison with transthoracic echocardiography

    International Nuclear Information System (INIS)

    Goo, Hyun Woo

    2018-01-01

    Considering inherent limitations of transthoracic echocardiography, the diagnostic accuracy of cardiac CT in identifying coronary artery anatomy before arterial switch operation needs to be investigated with recently improved coronary artery visibility using electrocardiogram (ECG)-synchronized dual-source CT. To compare diagnostic accuracy between cardiac CT using a dual-source scanner and transthoracic echocardiography in identifying coronary artery anatomy before arterial switch operation in newborns and young infants. The study included 101 infants (median age 4 days, range 0 days to 10 months; M:F=78:23) who underwent ECG-synchronized cardiac dual-source CT and transthoracic echocardiography before arterial switch operation between July 2011 and December 2016. We evaluated and classified coronary artery anatomy on cardiac CT and transthoracic echocardiography. With the surgical findings as the reference standard, we compared the diagnostic accuracy for identifying coronary artery anatomy between cardiac CT and transthoracic echocardiography. The most common coronary artery pattern was the usual pattern (left coronary artery from sinus 1 and right coronary artery from sinus 2; 64.4%, 65/101), followed by a single coronary artery from sinus 2 and a conal branch from sinus 1 (7.9%, 8/101), the inverted pattern (5.9%, 6/101), the right coronary artery and left anterior descending artery from sinus 1 and the left circumflex artery from sinus 2 (5.9%, 6/101), and others. In 96 infants with surgically proven coronary artery anatomy, the diagnostic accuracy of cardiac CT was significantly higher than that of transthoracic echocardiography (91.7%, 88/96 vs. 54.2%, 52/96; P<0.0001). Diagnostic accuracy of cardiac CT is significantly higher than that of echocardiography in identifying coronary artery anatomy before arterial switch operation in newborns and young infants. (orig.)

  4. In-flight particle measurement of glass raw materials in hybrid heating of twelve-phase AC arc with oxygen burner

    International Nuclear Information System (INIS)

    Liu, Y; Tanaka, M; Ikeba, T; Choi, S; Watanabe, T

    2012-01-01

    The high temperature provided by a 12-phase AC arc plasma is beneficial to finish vitrification reaction in milliseconds. Another heating method called “hybrid plasma” combines multi-phase AC arc and oxygen burner are expected to improve glass quality and increase productivity with minimum energy consumption. In this study, recent works on the development of in-flight particle measurement in hybrid plasma system are presented. Two-colour pyrometry offers considerable advantages for measuring particle temperatures in flight. A high-speed camera equipped with a band-pass filter system was applied to measure the in-flight temperatures of glass particles. The intensity recorded by the camera was calibrated using a tungsten halogen lamp. This technique also allows evaluating the fluctuation of the average particle temperature within millisecond in plasma region.

  5. Critical stenosis of a right ventricle to coronary artery fistula seen at dual-source CT in a newborn with pulmonary atresia and intact ventricular septum

    Energy Technology Data Exchange (ETDEWEB)

    Seguela, Pierre-Emmanuel [Centre Chirurgical Marie Lannelongue, Department of Pediatric Cardiology, Le Plessis-Robinson (France); Hopital des Enfants, Toulouse Cedex 9 (France); Houyel, Lucile; Piot, Jean-Dominique [Centre Chirurgical Marie Lannelongue, Department of Pediatric Cardiology, Le Plessis-Robinson (France); Loget, Philippe [Centre Hospitalier Universitaire de Rennes, Department of Pathology, Rennes (France); Paul, Jean-Francois [Centre Chirurgical Marie Lannelongue, Department of Pediatric Radiology, Le Plessis-Robinson (France)

    2011-08-15

    We report the case of a newborn with pulmonary atresia with intact ventricular septum and right ventricle-dependent coronary circulation. He died several weeks after a Blalock-Taussig procedure because of a progressive stenosis of the main coronary artery. We present echocardiographic and dual-source CT images of the stenosis, with autopsy correlation. To our knowledge, CT images of this quality have never been reported in a newborn. This case illustrates the extreme difficulty in prognosticating the outcome for these patients and underlines the need for a detailed neonatal coronary mapping to assess right ventricle-dependent coronary circulation. (orig.)

  6. Analytic solution of the two-dimensional Fokker-Planck equation governing stochastic ion heating by a lower hybrid wave

    International Nuclear Information System (INIS)

    Malescio, G.

    1981-04-01

    The two-dimensional Fokker-Planck equation describing the ion motion in a coherent lower hybrid wave above the stochasticity threshold is analytically solved. An expression is given for the steady state power dissipation

  7. A hybrid geothermal energy conversion technology: Auxiliary heating of geothermally preheated water or CO2 - a potential solution for low-temperature resources

    Science.gov (United States)

    Saar, Martin; Garapati, Nagasree; Adams, Benjamin; Randolph, Jimmy; Kuehn, Thomas

    2016-04-01

    Safe, sustainable, and economic development of deep geothermal resources, particularly in less favourable regions, often requires employment of unconventional geothermal energy extraction and utilization methods. Often "unconventional geothermal methods" is synonymously and solely used as meaning enhanced geothermal systems, where the permeability of hot, dry rock with naturally low permeability at greater depths (4-6 km), is enhanced. Here we present an alternative unconventional geothermal energy utilization approach that uses low-temperature regions that are shallower, thereby drastically reducing drilling costs. While not a pure geothermal energy system, this hybrid approach may enable utilization of geothermal energy in many regions worldwide that can otherwise not be used for geothermal electricity generation, thereby increasing the global geothermal resource base. Moreover, in some realizations of this hybrid approach that generate carbon dioxide (CO2), the technology may be combined with carbon dioxide capture and storage (CCS) and CO2-based geothermal energy utilization, resulting in a high-efficiency (hybrid) geothermal power plant with a negative carbon footprint. Typically, low- to moderate-temperature geothermal resources are more effectively used for direct heat energy applications. However, due to high thermal losses during transport, direct use requires that the heat resource is located near the user. Alternatively, we show here that if such a low-temperature geothermal resource is combined with an additional or secondary energy resource, the power production is increased compared to the sum from two separate (geothermal and secondary fuel) power plants (DiPippo et al. 1978) and the thermal losses are minimized because the thermal energy is utilized where it is produced. Since Adams et al. (2015) found that using CO2 as a subsurface working fluid produces more net power than brine at low- to moderate-temperature geothermal resource conditions, we

  8. Dual-source cardiac computed tomography angiography (CCTA) in the follow-up of cardiac transplant: comparison of image quality and radiation dose using three different imaging protocols

    International Nuclear Information System (INIS)

    Beitzke, D.; Berger-Kulemann, V.; Unterhumer, S.; Loewe, C.; Wolf, F.; Schoepf, V.; Spitzer, E.; Feuchtner, G.M.; Gyoengyoesi, M.; Uyanik-Uenal, K.; Zuckermann, A.

    2015-01-01

    To prospectively evaluate image quality (IQ) and radiation dose of dual-source cardiac computed tomography (CCTA) using different imaging protocols. CCTA was performed in 150 patients using the retrospective ECG-gated spiral technique (rECG) the prospective ECG-gated technique (pECG), or the prospective ECG-gated technique with systolic imaging and automated tube voltage selection (pECGsys). IQ was rated using a 16-segment coronary artery model. Techniques were compared for overall IQ, IQ of the large and the small coronary artery segments. Effective dose was used for comparison of radiation dose. Overall IQ and IQ of the large segments showed no differences between the groups. IQ analysis of the small segments showed lowered IQ in pECGsys compared to rECG (p = 0.02), but not to pECG (p = 0.6). Effective dose did not differ significantly between rECG and pECG (p = 0.13), but was significantly lower for pECGsys (p < 0.001 vs. rECG and pECG). Radiation dose of dual-source CCTA in heart transplant recipients is significantly reduced by using prospective systolic scanning and automated tube voltage selection, while overall IQ and IQ of the large coronary segments are maintained. IQ appears to be lower compared to retrospective techniques with regard to small coronary segments. (orig.)

  9. Contrast volume reduction using third generation dual source computed tomography for the evaluation of patients prior to transcatheter aortic valve implantation

    Energy Technology Data Exchange (ETDEWEB)

    Bittner, Daniel O. [University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nuernberg (FAU), Department of Internal Medicine 2 (Cardiology), Erlangen (Germany); Harvard Medical School, Cardiac MR PET CT Program, Massachusetts General Hospital, Boston, MA (United States); Arnold, Martin; Klinghammer, Lutz; Schuhbaeck, Annika; Hell, Michaela M.; Muschiol, Gerd; Gauss, Soeren; Achenbach, Stephan; Marwan, Mohamed [University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nuernberg (FAU), Department of Internal Medicine 2 (Cardiology), Erlangen (Germany); Lell, Michael; Uder, Michael [University Hospital Erlangen, Friedrich-Alexander University Erlangen-Nuernberg (FAU), Department of Radiology, Erlangen (Germany); Hoffmann, Udo [Harvard Medical School, Cardiac MR PET CT Program, Massachusetts General Hospital, Boston, MA (United States)

    2016-12-15

    Chronic renal failure is common in patients referred for transcatheter aortic valve implantation (TAVI). CT angiography is recommended and provides crucial information prior to TAVI. We evaluated the feasibility of a reduced contrast volume protocol for pre-procedural CT imaging. Forty consecutive patients were examined with prospectively ECG-triggered high-pitch spiral acquisition using a novel third-generation dual-source CT system; 38 ml contrast agent was used. Image quality was graded on a visual scale (1-4). Contrast attenuation was measured at the level of the aortic root and at the iliac bifurcation. Mean patient age was 82 ± 6 years (23 males; 58 %). Mean attenuation/average image quality was 285 ± 60 HU/1.5 at the aortic annulus compared to 289 ± 74 HU/1.8 at the iliac bifurcation (p = 0.77/p = 0.29). Mean estimated effective radiation dose was 2.9 ± 0.3 mSv. A repeat acquisition was necessary in one patient due to image quality. Out of the 35 patients who underwent TAVI, 31 (89 %) patients had no or mild aortic regurgitation. Thirty-two (91 %) patients were discharged successfully. Pre-procedural CTA with a total of 38 ml contrast volume is feasible and clinically useful, using third-generation dual-source CT, allowing comprehensive imaging for procedural success. (orig.)

  10. Dual-source cardiac computed tomography angiography (CCTA) in the follow-up of cardiac transplant: comparison of image quality and radiation dose using three different imaging protocols

    Energy Technology Data Exchange (ETDEWEB)

    Beitzke, D.; Berger-Kulemann, V.; Unterhumer, S.; Loewe, C.; Wolf, F. [Medical University Vienna, Department of Biomedical Imaging and Image Guided Therapy, Division of Cardiovascular and Interventional Radiology, Vienna (Austria); Schoepf, V. [Medical University Vienna, Department of Biomedical Imaging and Image Guided Therapy, Division of Neuroradiology and Musculoskeletal Radiology, Vienna (Austria); Spitzer, E. [Bern University Hospital, Department of Cardiology, Bern (Switzerland); Feuchtner, G.M. [Innsbruck Medical University, Department of Radiology II, Innsbruck (Austria); Gyoengyoesi, M. [Medical University Vienna, Department of Cardiology, Vienna (Austria); Uyanik-Uenal, K.; Zuckermann, A. [Medical University Vienna, Department of Cardiac Surgery, Vienna (Austria)

    2015-08-15

    To prospectively evaluate image quality (IQ) and radiation dose of dual-source cardiac computed tomography (CCTA) using different imaging protocols. CCTA was performed in 150 patients using the retrospective ECG-gated spiral technique (rECG) the prospective ECG-gated technique (pECG), or the prospective ECG-gated technique with systolic imaging and automated tube voltage selection (pECGsys). IQ was rated using a 16-segment coronary artery model. Techniques were compared for overall IQ, IQ of the large and the small coronary artery segments. Effective dose was used for comparison of radiation dose. Overall IQ and IQ of the large segments showed no differences between the groups. IQ analysis of the small segments showed lowered IQ in pECGsys compared to rECG (p = 0.02), but not to pECG (p = 0.6). Effective dose did not differ significantly between rECG and pECG (p = 0.13), but was significantly lower for pECGsys (p < 0.001 vs. rECG and pECG). Radiation dose of dual-source CCTA in heart transplant recipients is significantly reduced by using prospective systolic scanning and automated tube voltage selection, while overall IQ and IQ of the large coronary segments are maintained. IQ appears to be lower compared to retrospective techniques with regard to small coronary segments. (orig.)

  11. Ultra-low dose dual-source high-pitch computed tomography of the paranasal sinus: diagnostic sensitivity and radiation dose

    International Nuclear Information System (INIS)

    Schulz, Boris; Zangos, Stefan; Friedrichs, Ingke; Bauer, Ralf W.; Kerl, Matthias; Vogl, Thomas J.; Martin M Mack, Martin M.; Potente, Stefan

    2012-01-01

    Background: Today's gold standard for diagnostic imaging of inflammatory diseases of the paranasal sinus is computed tomography (CT). Purpose: To evaluate diagnostic sensitivity and radiation dose of an ultra-low dose dual-source CT technique. Material and Methods: Paranasal sinuses of 14 cadaveric heads were independently evaluated by two readers using a modern dual-source CT with lowest reasonable dosage in high-pitch mode (100 kV, 10 mAs, collimation 0.6 mm, pitch value 3.0). Additionally the head part of an anthropomorphic Alderson-Rando phantom was equipped with thermoluminescent detectors to measure radiation exposure to the eye lenses and thyroid gland. Results: Diagnostic accuracy regarding sinusoidal fluid, nasal septum deviation, and mucosal swelling was 100%. Mastoid fluid was detected in 76% and 92%, respectively. In the phantom study, average measured eye lens dosage was 0.64 mGy; radiation exposure of the thyroid gland was 0.085 mGy. Conclusion: Regarding evaluation of inflammatory diseases of the paranasal sinus this study indicates sufficient accuracy of the proposed CT protocol at a very low dosage level

  12. Screening for coronary artery disease in respiratory patients: comparison of single- and dual-source CT in patients with a heart rate above 70 bpm

    International Nuclear Information System (INIS)

    Pansini, Vittorio; Remy-Jardin, Martine; Tacelli, Nunzia; Faivre, Jean-Baptiste; Remy, Jacques; Flohr, Thomas; Deken, Valerie; Duhamel, Alain

    2008-01-01

    To evaluate the assessibility of coronary arteries in respiratory patients with high heart rates. This study was based on the comparative analysis of two paired populations of 54 patients with a heart rate >70 bpm evaluated with dual-source (group 1) and single-source (group 2) CT. The mean heart rate was 89.1 bpm in group 1 and 86.7 bpm in group 2 (P=0.26). The mean number of assessable segments per patient was significantly higher in group 1 compared to group 2 (P≤0.0001). The proportions of patients in whom proximal and mid-coronary segments were assessable (i.e., the anatomical level enabling screening for asymptomatic coronary artery disease) were 35.3% for heart rates <110 bpm, 35.6% for heart rates <100 bpm, 40% for heart rates <90 bpm, and 60% for heart rates <80 bpm in group 1 and 11.3, 12.2, 8.8, and 10% for the corresponding thresholds in group 2 (P<0.05). In both groups of patients, coronary artery imaging was obtained from standard CT angiograms of the chest. The improvement in coronary imaging with dual-source CT suggests that high heart rates should no longer be considered as contraindications for ECG-gated CT angiograms of the chest whenever clinically relevant. (orig.)

  13. Cardiac MOLLI T1 mapping at 3.0 T: comparison of patient-adaptive dual-source RF and conventional RF transmission.

    Science.gov (United States)

    Rasper, Michael; Nadjiri, Jonathan; Sträter, Alexandra S; Settles, Marcus; Laugwitz, Karl-Ludwig; Rummeny, Ernst J; Huber, Armin M

    2017-06-01

    To prospectively compare image quality and myocardial T 1 relaxation times of modified Look-Locker inversion recovery (MOLLI) imaging at 3.0 T (T) acquired with patient-adaptive dual-source (DS) and conventional single-source (SS) radiofrequency (RF) transmission. Pre- and post-contrast MOLLI T 1 mapping using SS and DS was acquired in 27 patients. Patient wise and segment wise analysis of T 1 times was performed. The correlation of DS MOLLI measurements with a reference spin echo sequence was analysed in phantom experiments. DS MOLLI imaging reduced T 1 standard deviation in 14 out of 16 myocardial segments (87.5%). Significant reduction of T 1 variance could be obtained in 7 segments (43.8%). DS significantly reduced myocardial T 1 variance in 16 out of 25 patients (64.0%). With conventional RF transmission, dielectric shading artefacts occurred in six patients causing diagnostic uncertainty. No according artefacts were found on DS images. DS image findings were in accordance with conventional T 1 mapping and late gadolinium enhancement (LGE) imaging. Phantom experiments demonstrated good correlation of myocardial T 1 time between DS MOLLI and spin echo imaging. Dual-source RF transmission enhances myocardial T 1 homogeneity in MOLLI imaging at 3.0 T. The reduction of signal inhomogeneities and artefacts due to dielectric shading is likely to enhance diagnostic confidence.

  14. Dual-source spiral CT with pitch up to 3.2 and 75 ms temporal resolution: Image reconstruction and assessment of image quality

    International Nuclear Information System (INIS)

    Flohr, Thomas G.; Leng Shuai; Yu Lifeng; Allmendinger, Thomas; Bruder, Herbert; Petersilka, Martin; Eusemann, Christian D.; Stierstorfer, Karl; Schmidt, Bernhard; McCollough, Cynthia H.

    2009-01-01

    Purpose: To present the theory for image reconstruction of a high-pitch, high-temporal-resolution spiral scan mode for dual-source CT (DSCT) and evaluate its image quality and dose. Methods: With the use of two x-ray sources and two data acquisition systems, spiral CT exams having a nominal temporal resolution per image of up to one-quarter of the gantry rotation time can be acquired using pitch values up to 3.2. The scan field of view (SFOV) for this mode, however, is limited to the SFOV of the second detector as a maximum, depending on the pitch. Spatial and low contrast resolution, image uniformity and noise, CT number accuracy and linearity, and radiation dose were assessed using the ACR CT accreditation phantom, a 30 cm diameter cylindrical water phantom or a 32 cm diameter cylindrical PMMA CTDI phantom. Slice sensitivity profiles (SSPs) were measured for different nominal slice thicknesses, and an anthropomorphic phantom was used to assess image artifacts. Results were compared between single-source scans at pitch=1.0 and dual-source scans at pitch=3.2. In addition, image quality and temporal resolution of an ECG-triggered version of the DSCT high-pitch spiral scan mode were evaluated with a moving coronary artery phantom, and radiation dose was assessed in comparison with other existing cardiac scan techniques. Results: No significant differences in quantitative measures of image quality were found between single-source scans at pitch=1.0 and dual-source scans at pitch=3.2 for spatial and low contrast resolution, CT number accuracy and linearity, SSPs, image uniformity, and noise. The pitch value (1.6≤pitch≤3.2) had only a minor impact on radiation dose and image noise when the effective tube current time product (mA s/pitch) was kept constant. However, while not severe, artifacts were found to be more prevalent for the dual-source pitch=3.2 scan mode when structures varied markedly along the z axis, particularly for head scans. Images of the moving

  15. Dual-source spiral CT with pitch up to 3.2 and 75 ms temporal resolution: image reconstruction and assessment of image quality.

    Science.gov (United States)

    Flohr, Thomas G; Leng, Shuai; Yu, Lifeng; Aiimendinger, Thomas; Bruder, Herbert; Petersilka, Martin; Eusemann, Christian D; Stierstorfer, Karl; Schmidt, Bernhard; McCollough, Cynthia H

    2009-12-01

    To present the theory for image reconstruction of a high-pitch, high-temporal-resolution spiral scan mode for dual-source CT (DSCT) and evaluate its image quality and dose. With the use of two x-ray sources and two data acquisition systems, spiral CT exams having a nominal temporal resolution per image of up to one-quarter of the gantry rotation time can be acquired using pitch values up to 3.2. The scan field of view (SFOV) for this mode, however, is limited to the SFOV of the second detector as a maximum, depending on the pitch. Spatial and low contrast resolution, image uniformity and noise, CT number accuracy and linearity, and radiation dose were assessed using the ACR CT accreditation phantom, a 30 cm diameter cylindrical water phantom or a 32 cm diameter cylindrical PMMA CTDI phantom. Slice sensitivity profiles (SSPs) were measured for different nominal slice thicknesses, and an anthropomorphic phantom was used to assess image artifacts. Results were compared between single-source scans at pitch = 1.0 and dual-source scans at pitch = 3.2. In addition, image quality and temporal resolution of an ECG-triggered version of the DSCT high-pitch spiral scan mode were evaluated with a moving coronary artery phantom, and radiation dose was assessed in comparison with other existing cardiac scan techniques. No significant differences in quantitative measures of image quality were found between single-source scans at pitch = 1.0 and dual-source scans at pitch = 3.2 for spatial and low contrast resolution, CT number accuracy and linearity, SSPs, image uniformity, and noise. The pitch value (1.6 pitch 3.2) had only a minor impact on radiation dose and image noise when the effective tube current time product (mA s/pitch) was kept constant. However, while not severe, artifacts were found to be more prevalent for the dual-source pitch = 3.2 scan mode when structures varied markedly along the z axis, particularly for head scans. Images of the moving coronary artery phantom

  16. Dual-source spiral CT with pitch up to 3.2 and 75 ms temporal resolution: Image reconstruction and assessment of image quality

    Energy Technology Data Exchange (ETDEWEB)

    Flohr, Thomas G.; Leng Shuai; Yu Lifeng; Allmendinger, Thomas; Bruder, Herbert; Petersilka, Martin; Eusemann, Christian D.; Stierstorfer, Karl; Schmidt, Bernhard; McCollough, Cynthia H. [Siemens Healthcare, Computed Tomography, 91301 Forchheim, Germany and Department of Diagnostic Radiology, Eberhard-Karls-Universitaet, 72076 Tuebingen (Germany); Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905 (United States); Siemens Healthcare, Computed Tomography, 91301 Forchheim (Germany); Department of Radiology, Mayo Clinic, Rochester, Minnesota 55905 (United States)

    2009-12-15

    Purpose: To present the theory for image reconstruction of a high-pitch, high-temporal-resolution spiral scan mode for dual-source CT (DSCT) and evaluate its image quality and dose. Methods: With the use of two x-ray sources and two data acquisition systems, spiral CT exams having a nominal temporal resolution per image of up to one-quarter of the gantry rotation time can be acquired using pitch values up to 3.2. The scan field of view (SFOV) for this mode, however, is limited to the SFOV of the second detector as a maximum, depending on the pitch. Spatial and low contrast resolution, image uniformity and noise, CT number accuracy and linearity, and radiation dose were assessed using the ACR CT accreditation phantom, a 30 cm diameter cylindrical water phantom or a 32 cm diameter cylindrical PMMA CTDI phantom. Slice sensitivity profiles (SSPs) were measured for different nominal slice thicknesses, and an anthropomorphic phantom was used to assess image artifacts. Results were compared between single-source scans at pitch=1.0 and dual-source scans at pitch=3.2. In addition, image quality and temporal resolution of an ECG-triggered version of the DSCT high-pitch spiral scan mode were evaluated with a moving coronary artery phantom, and radiation dose was assessed in comparison with other existing cardiac scan techniques. Results: No significant differences in quantitative measures of image quality were found between single-source scans at pitch=1.0 and dual-source scans at pitch=3.2 for spatial and low contrast resolution, CT number accuracy and linearity, SSPs, image uniformity, and noise. The pitch value (1.6{<=}pitch{<=}3.2) had only a minor impact on radiation dose and image noise when the effective tube current time product (mA s/pitch) was kept constant. However, while not severe, artifacts were found to be more prevalent for the dual-source pitch=3.2 scan mode when structures varied markedly along the z axis, particularly for head scans. Images of the moving

  17. 4E analysis and multi objective optimization of a micro gas turbine and solid oxide fuel cell hybrid combined heat and power system

    Science.gov (United States)

    Sanaye, Sepehr; Katebi, Arash

    2014-02-01

    Energy, exergy, economic and environmental (4E) analysis and optimization of a hybrid solid oxide fuel cell and micro gas turbine (SOFC-MGT) system for use as combined generation of heat and power (CHP) is investigated in this paper. The hybrid system is modeled and performance related results are validated using available data in literature. Then a multi-objective optimization approach based on genetic algorithm is incorporated. Eight system design parameters are selected for the optimization procedure. System exergy efficiency and total cost rate (including capital or investment cost, operational cost and penalty cost of environmental emissions) are the two objectives. The effects of fuel unit cost, capital investment and system power output on optimum design parameters are also investigated. It is observed that the most sensitive and important design parameter in the hybrid system is fuel cell current density which has a significant effect on the balance between system cost and efficiency. The selected design point from the Pareto distribution of optimization results indicates a total system exergy efficiency of 60.7%, with estimated electrical energy cost 0.057 kW-1 h-1, and payback period of about 6.3 years for the investment.

  18. A novel hybrid tobacco product that delivers a tobacco flavour note with vapour aerosol (Part 2): In vitro biological assessment and comparison with different tobacco-heating products.

    Science.gov (United States)

    Breheny, Damien; Adamson, Jason; Azzopardi, David; Baxter, Andrew; Bishop, Emma; Carr, Tony; Crooks, Ian; Hewitt, Katherine; Jaunky, Tomasz; Larard, Sophie; Lowe, Frazer; Oke, Oluwatobiloba; Taylor, Mark; Santopietro, Simone; Thorne, David; Zainuddin, Benjamin; Gaça, Marianna; Liu, Chuan; Murphy, James; Proctor, Christopher

    2017-08-01

    This study assessed the toxicological and biological responses of aerosols from a novel hybrid tobacco product. Toxicological responses from the hybrid tobacco product were compared to those from a commercially available Tobacco Heating Product (c-THP), a prototype THP (p-THP) and a 3R4F reference cigarette, using in vitro test methods which were outlined as part of a framework to substantiate the risk reduction potential of novel tobacco and nicotine products. Exposure matrices used included total particulate matter (TPM), whole aerosol (WA), and aqueous aerosol extracts (AqE) obtained after machine-puffing the test products under the Health Canada Intense smoking regime. Levels of carbonyls and nicotine in these matrices were measured to understand the aerosol dosimetry of the products. The hybrid tobacco product tested negative across the in vitro assays including mutagenicity, genotoxicity, cytotoxicity, tumour promotion, oxidative stress and endothelial dysfunction. All the THPs tested demonstrated significantly reduced responses in these in vitro assays when compared to 3R4F. The findings suggest these products have the potential for reduced health risks. Further pre-clinical and clinical assessments are required to substantiate the risk reduction of these novel products at individual and population levels. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  19. The Role of Combined ICRF and NBI Heating in JET Hybrid Plasmas in Quest for High D-T Fusion Yield

    Directory of Open Access Journals (Sweden)

    Mantsinen Mervi

    2017-01-01

    Full Text Available Combined ICRF and NBI heating played a key role in achieving the world-record fusion yield in the first deuterium-tritium campaign at the JET tokamak in 1997. The current plans for JET include new experiments with deuterium-tritium (D-T plasmas with more ITER-like conditions given the recently installed ITER-like wall (ILW. In the 2015-2016 campaigns, significant efforts have been devoted to the development of high-performance plasma scenarios compatible with ILW in preparation of the forthcoming D-T campaign. Good progress was made in both the inductive (baseline and the hybrid scenario: a new record JET ILW fusion yield with a significantly extended duration of the high-performance phase was achieved. This paper reports on the progress with the hybrid scenario which is a candidate for ITER longpulse operation (∼1000 s thanks to its improved normalized confinement, reduced plasma current and higher plasma beta with respect to the ITER reference baseline scenario. The combined NBI+ICRF power in the hybrid scenario was increased to 33 MW and the record fusion yield, averaged over 100 ms, to 2.9x1016 neutrons/s from the 2014 ILW fusion record of 2.3x1016 neutrons/s. Impurity control with ICRF waves was one of the key means for extending the duration of the high-performance phase. The main results are reviewed covering both key core and edge plasma issues.

  20. Selection of appropriate working fluids for Rankine cycles used for recovery of heat from exhaust gases of ICE in heavy-duty series hybrid electric vehicles

    International Nuclear Information System (INIS)

    Jung, Daebong; Park, Sungjin; Min, Kyoungdoug

    2015-01-01

    Recently, the waste heat recovery system is studied for application in vehicles to improve fuel economy. Especially, Rankine cycle is representative and attractive technology as waste heat recovery system. In order to maximize efficiency of Rankine cycle in the vehicle application, selection of optimal working fluid is important. Thus, in this study, thermodynamic analysis with consideration of practical operating condition was conducted to find out optimal working fluids. Thermodynamic efficiency, recovery efficiency, and overall cycle efficiency were adopted to estimate Rankine cycle performance. In order to reflect practical operating condition on the analysis, limitations due to working fluid physical properties and components specifications are taken into account. 5 working fluids including dry and wet fluid were used to estimate efficiency. Consequently, R245fa which shows high efficiency and environment-friendly is suggested as optimal working fluid in vehicle application. - Highlights: • 5 different working fluids were analyzed in respect of hybrid electric vehicle waste heat recovery system. • Real world operational conditions and limits are applied. • Optimal heating temperature of each working fluid show different trend. • R245fa is preferable among other fluids due to its high efficiency and impact on environment

  1. Hybrid MoS2/h-BN Nanofillers As Synergic Heat Dissipation and Reinforcement Additives in Epoxy Nanocomposites.

    Science.gov (United States)

    Ribeiro, Hélio; Trigueiro, João Paulo C; Silva, Wellington M; Woellner, Cristiano F; Owuor, Peter S; Cristian Chipara, Alin; Lopes, Magnovaldo C; Tiwary, Chandra S; Pedrotti, Jairo J; Villegas Salvatierra, Rodrigo; Tour, James M; Chopra, Nitin; Odeh, Ihab N; Silva, Glaura G; Ajayan, Pulickel M

    2017-09-26

    Two-dimensional (2D) nanomaterials as molybdenum disulfide (MoS 2 ), hexagonal boron nitride (h-BN), and their hybrid (MoS 2 /h-BN) were employed as fillers to improve the physical properties of epoxy composites. Nanocomposites were produced in different concentrations and studied in their microstructure, mechanical and thermal properties. The hybrid 2D mixture imparted efficient reinforcement to the epoxy leading to increases of up to 95% in tensile strength, 60% in ultimate strain, and 58% in Young's modulus. Moreover, an enhancement of 203% in thermal conductivity was achieved for the hybrid composite as compared to the pure polymer. The incorporation of MoS 2 /h-BN mixture nanofillers in epoxy resulted in nanocomposites with multifunctional characteristics for applications that require high mechanical and thermal performance.

  2. Detecting Intracranial Hemorrhage Using Automatic Tube Current Modulation With Advanced Modeled Iterative Reconstruction in Unenhanced Head Single- and Dual-Energy Dual-Source CT.

    Science.gov (United States)

    Scholtz, Jan-Erik; Wichmann, Julian L; Bennett, Dennis W; Leithner, Doris; Bauer, Ralf W; Vogl, Thomas J; Bodelle, Boris

    2017-05-01

    The purpose of our study was to determine diagnostic accuracy, image quality, and radiation dose of low-dose single- and dual-energy unenhanced third-generation dual-source head CT for detection of intracranial hemorrhage (ICH). A total of 123 patients with suspected ICH were examined using a dual-source 192-MDCT scanner. Standard-dose 120-kVp single-energy CT (SECT; n = 36) and 80-kVp and 150-kVp dual-energy CT (DECT; n = 30) images were compared with low-dose SECT (n = 32) and DECT (n = 25) images obtained using automated tube current modulation (ATCM). Advanced modeled iterative reconstruction (ADMIRE) was used for all protocols. Detection of ICH was performed by three readers who were blinded to the image acquisition parameters of each image series. Image quality was assessed both quantitatively and qualitatively. Interobserver agreement was calculated using the Fleiss kappa. Radiation dose was measured as dose-length product (DLP). Detection of ICH was excellent (sensitivity, 94.9-100%; specificity, 94.7-100%) in all protocols (p = 1.00) with perfect interobserver agreement (0.83-0.96). Qualitative ratings showed significantly better ratings for both standard-dose protocols regarding gray matter-to-white matter contrast (p ≤ 0.014), whereas highest gray matter-to-white matter contrast-to-noise ratio was observed with low-dose DECT images (p ≥ 0.057). The lowest posterior fossa artifact index was measured for standard-dose DECT, which showed significantly lower values compared with low-dose protocols (p ≤ 0.034). Delineation of ventricular margins and sharpness of subarachnoidal spaces were rated excellent in all protocols (p ≥ 0.096). Low-dose techniques lowered radiation dose by 26% for SECT images (DLP, 575.0 ± 72.3 mGy · cm vs 771.5 ± 146.8 mGy · cm; p dual-source CT while allowing significant radiation dose reduction.

  3. Image quality and radiation dose of lower extremity CT angiography at 70 kVp on an integrated circuit detector dual-source computed tomography.

    Science.gov (United States)

    Qi, Li; Zhao, Yan'E; Zhou, Chang Sheng; Spearman, James V; Renker, Matthias; Schoepf, U Joseph; Zhang, Long Jiang; Lu, Guang Ming

    2015-06-01

    Despite the well-established requirement for radiation dose reduction there are few studies examining the potential for lower extremity CT angiography (CTA) at 70 kVp. To compare the image quality and radiation dose of lower extremity CTA at 70 kVp using a dual-source CT system with an integrated circuit detector to similar studies at 120 kVp. A total of 62 patients underwent lower extremity CTA. Thirty-one patients were examined at 70 kVp using a second generation dual-source CT with an integrated circuit detector (70 kVp group) and 31 patients were evaluated at 120 kVp using a first generation dual-source CT (120 kVp group). The attenuation and image noise were measured and signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Two radiologists assessed image quality. Radiation dose was compared. The mean attenuation of the 70 kVp group was higher than the 120 kVp group (575 ± 149 Hounsfield units [HU] vs. 258 ± 38 HU, respectively, P < 0.001) as was SNR (44.0 ± 22.0 vs 32.7 ± 13.3, respectively, P = 0.017), CNR (39.7 ± 20.6 vs 26.6 ± 11.7, respectively, P = 0.003) and the mean image quality score (3.7 ± 0.1 vs. 3.2 ± 0.3, respectively, P < 0.001). The inter-observer agreement was good for the 70 kVp group and moderate for the 120 kVp group. The dose-length product was lower in the 70 kVp group (264.5 ± 63.1 mGy × cm vs. 412.4 ± 81.5 mGy × cm, P < 0.001). Lower extremity CTA at 70 kVp allows for lower radiation dose with higher SNR, CNR, and image quality when compared with standard 120 kVp. © The Foundation Acta Radiologica 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  4. SU-G-IeP2-15: Virtual Insertion of Digital Kidney Stones Into Dual-Source, Dual- Energy CT Projection Data

    International Nuclear Information System (INIS)

    Ferrero, A; Chen, B; Huang, A; Montoya, J; Yu, L; McCollough, C

    2016-01-01

    Purpose: In order to investigate novel methods to more accurately estimate the mineral composition of kidney stones using dual energy CT, it is desirable to be able to combine digital stones of known composition with actual phantom and patient scan data. In this work, we developed and validated a method to insert digital kidney stones into projection data acquired on a dual-source, dual-energy CT system. Methods: Attenuation properties of stones of different mineral composition were computed using tabulated mass attenuation coefficients, the chemical formula for each stone type, and the effective beam energy at each evaluated tube potential. A previously developed method to insert lesions into x-ray CT projection data was extended to include simultaneous dual-energy CT projections acquired on a dual-source gantry (Siemens Somatom Flash). Digital stones were forward projected onto both detectors and the resulting projections added to the physically acquired sinogram data. To validate the accuracy of the technique, digital stones were inserted into different locations in the ACR CT accreditation phantom; low and high contrast resolution, CT number accuracy and noise properties were compared before and after stone insertion. The procedure was repeated for two dual-energy tube potential pairs in clinical use on the scanner, 80/Sn140 kV and 100/Sn140 kV, respectively. Results: The images reconstructed after the insertion of digital kidney stones were consistent with the images reconstructed from the scanner. The largest average CT number difference for the 4 insert in the CT number accuracy module of the phantom was 3 HU. Conclusion: A framework was developed and validated for the creation of digital kidney stones of known mineral composition, and their projection-domain insertion into commercial dual-source, dual-energy CT projection data. This will allow a systematic investigation of the impact of scan and reconstruction parameters on stone attenuation and dual

  5. Plantation forestry under global warming: hybrid poplars with improved thermotolerance provide new insights on the in vivo function of small heat shock protein chaperones.

    Science.gov (United States)

    Merino, Irene; Contreras, Angela; Jing, Zhong-Ping; Gallardo, Fernando; Cánovas, Francisco M; Gómez, Luis

    2014-02-01

    Climate-driven heat stress is a key factor affecting forest plantation yields. While its effects are expected to worsen during this century, breeding more tolerant genotypes has proven elusive. We report here a substantial and durable increase in the thermotolerance of hybrid poplar (Populus tremula×Populus alba) through overexpression of a major small heat shock protein (sHSP) with convenient features. Experimental evidence was obtained linking protective effects in the transgenic events with the unique chaperone activity of sHSPs. In addition, significant positive correlations were observed between phenotype strength and heterologous sHSP accumulation. The remarkable baseline levels of transgene product (up to 1.8% of total leaf protein) have not been reported in analogous studies with herbaceous species. As judged by protein analyses, such an accumulation is not matched either by endogenous sHSPs in both heat-stressed poplar plants and field-grown adult trees. Quantitative real time-polymerase chain reaction analyses supported these observations and allowed us to identify the poplar members most responsive to heat stress. Interestingly, sHSP overaccumulation was not associated with pleiotropic effects that might decrease yields. The poplar lines developed here also outperformed controls under in vitro and ex vitro culture conditions (callus biomass, shoot production, and ex vitro survival), even in the absence of thermal stress. These results reinforce the feasibility of improving valuable genotypes for plantation forestry, a field where in vitro recalcitrance, long breeding cycles, and other practical factors constrain conventional genetic approaches. They also provide new insights into the biological functions of the least understood family of heat shock protein chaperones.

  6. A practical multi-objective design approach for optimum exhaust heat recovery from hybrid stand-alone PV-diesel power systems

    International Nuclear Information System (INIS)

    Yousefi, Moslem; Kim, Joong Hoon; Hooshyar, Danial; Yousefi, Milad; Sahari, Khairul Salleh Mohamed; Ahmad, Rodina Binti

    2017-01-01

    Highlights: • Heat recovery exchanger is designed based on practical conditions of a hybrid power system. • Off-the-grid electricity system modeling and analysis using micro-grid analysis software HOMER. • NSGA-II is used for the multi-objective design optimization task. • A new local search is proposed to incorporate the engineering knowledge in NSGA-II. • The proposed approach outperforms the existing ones. - Abstract: Integration of solar power and diesel generators (DGs) together with battery storage has proven to be an efficient choice for stand-alone power systems (SAPS). For higher energy efficiency, heat recovery from exhaust gas of the DG can also be employed to supply all or a portion of the thermal energy demand. Although the design of such heat recovery systems (HRSs) has been studied, the effect of solar power integration has not been taken into account. In this paper, a new approach for practical design of these systems based on varying engine loads is presented. Fast and elitist non-dominated sorting genetic algorithm (NSGA-II) equipped with a novel local search was used for the design process, considering conflicting objectives of annual energy recovery and total cost of the system, and six design variables. An integrated power system, designed for a remote SAPS, was used to evaluate the design approach. The optimum power supply system was first designed using the commercial software Hybrid Optimization of Multiple Energy Resources (HOMER), based on power demand and global solar energy in the region. Heat recovery design was based on the outcome of HOMER for DG hourly load, considering different power scenarios. The proposed approach improves the annual heat recovery of the PV/DG/battery system by 4%, PV/battery by 1.7%, and stand-alone DG by 1.8% when compared with a conventional design based on nominal DG load. The results prove that the proposed approach is effective and that load calculations should be taken into account prior to

  7. Reduction of thoracic aorta motion artifact with high-pitch 128-slice dual-source computed tomographic angiography: a historical control study.

    Science.gov (United States)

    Nakagawa, Junichiro; Tasaki, Osamu; Watanabe, Yoshiyuki; Azuma, Takeo; Ohnishi, Mitsuo; Ukai, Isao; Tahara, Kenichi; Ogura, Hiroshi; Kuwagata, Yasuyuki; Hamasaki, Toshimitsu; Shimazu, Takeshi

    2013-01-01

    Electrocardiogram-gated imaging combined with multi-detector row computed tomography (MDCT) has reduced cardiac motion artifacts, but it was not practical in the emergency setting. The purpose of this study was to evaluate the ability of a high-pitch, 128-slice dual-source CT (DSCT) scanner to reduce motion artifacts in patients admitted to the emergency room. This study comprised 100 patients suspected of having thoracic aorta lesions. We examined 47 patients with the 128-slice DSCT scanner (DSCT group), and 53 patients were examined with a 64-slice MDCT scanner (MDCT group). Six anatomic areas in the thoracic aorta were evaluated. Computed tomography images in the DSCT group were distinct, and significant differences were observed in images of all areas between the 2 groups except for the descending aorta. The high-pitch DSCT scanner can reduce motion artifacts of the thoracic aorta and enable radiological diagnosis even in patients with tachycardia and without breath hold.

  8. Hybrid system: Heat pump-solar air dryer for grains; Sistema hibrido: bomba de calor - calentador solar de aire para el secado de productos agricolas

    Energy Technology Data Exchange (ETDEWEB)

    Soto Gomez, Willfredo [Instituto Tecnologico de Tijuana, Tijuana (Mexico); Ortega Herrera, Jose Angel [Instituto Politecnico Nacional, Mexico, D.F. (Mexico)

    2000-07-01

    Design, building, operation and evaluation energy wise of a hybrid experimental type, with heat pump, that uses no chloride, does not destroy the ozone layer. It is solar air dryer for grains. In this research we dry rice. It has tree systems: 1.- A mechanical compression heat pump, 2.- An air solar heater, and 3.- An agriculture products dryer. The drying capacity is 20 pounds of grain /day, with a median daily solar radiation. The costs is approximately U.S. $ 6 000.00. The heat pump used 22 refrigerant first, and now works with refrigerant SUVA 9000. This refrigerant will be available this year in the I.S., it is one of the ecological class that substitutes the chlorofluorocarbonates. [Spanish] Se disena, construye, opera, y evalua energeticamente, un sistema hibrido tipo experimental, con bomba de calor que utiliza refrigerante que no contiene cloro, y no destruye la capa de ozono y un calentador solar de aire, para secar granos. En este trabajo secamos arroz. Se compone de tres sistemas: 1.- Bomba de calor por compresion mecanica, 2.- Calentador solar de aire, 3.- Secador de productos agricolas. La capacidad de secado es de 10 Kilos de granos/dia promedio. Tiene un costo aproximado de $ 60 000. La bomba de calor utiliza refrigerante 22 en una primera generacion, y actualmente opera con un refrigerante SUVA 9000, en una segunda generacion, este refrigerante se comercializara en este ano, en la Union Americana, pertenece a la familia de los llamados refrigerantes ecologicos, sustitutos de los clorofluorocarbonados.

  9. Proposal of a combined heat and power plant hybridized with regeneration organic Rankine cycle: Energy-Exergy evaluation

    International Nuclear Information System (INIS)

    Anvari, Simin; Jafarmadar, Samad; Khalilarya, Shahram

    2016-01-01

    Highlights: • A new thermodynamic cogeneration system is proposed. • Energy and exergy analysis of the considered cycle were performed. • An enhancement of 2.6% in exergy efficiency compared to that of baseline cycle. - Abstract: Among Rankine cycles (simple, reheat and regeneration), regeneration organic Rankine cycle demonstrates higher efficiencies compared to other cases. Consequently, in the present work a regeneration organic Rankine cycle has been utilized to recuperate gas turbine’s heat using heat recovery steam generator. At first, this cogeneration system was subjected to energy and exergy analysis and the obtained results were compared with that of investigated cogeneration found in literature (a cogeneration system in which a reheat organic Rankine cycle for heat recuperation of gas turbine cycle was used with the aid of heat recovery steam generator). Results indicated that the first and second thermodynamic efficiencies in present cycle utilizing regeneration cycle instead of reheat cycle has increased 2.62% and 2.6%, respectively. In addition, the effect of thermodynamic parameters such as combustion chamber’s inlet temperature, gas turbine inlet temperature, evaporator and condenser temperature on the energetic and exergetic efficiencies of gas turbine-heat recovery steam generator cycle and gas turbine-heat recovery steam generator cycle with regeneration organic Rankine cycle was surveyed. Besides, parametric analysis shows that as gas turbine and combustion chamber inlet temperatures increase, energetic and exergetic efficiencies tend to increase. Moreover, once condenser and evaporator temperature raise, a slight decrement in energetic and exergetic efficiency is expected.

  10. Temporal resolution measurement of 128-slice dual source and 320-row area detector computed tomography scanners in helical acquisition mode using the impulse method.

    Science.gov (United States)

    Hara, Takanori; Urikura, Atsushi; Ichikawa, Katsuhiro; Hoshino, Takashi; Nishimaru, Eiji; Niwa, Shinji

    2016-04-01

    To analyse the temporal resolution (TR) of modern computed tomography (CT) scanners using the impulse method, and assess the actual maximum TR at respective helical acquisition modes. To assess the actual TR of helical acquisition modes of a 128-slice dual source CT (DSCT) scanner and a 320-row area detector CT (ADCT) scanner, we assessed the TRs of various acquisition combinations of a pitch factor (P) and gantry rotation time (R). The TR of the helical acquisition modes for the 128-slice DSCT scanner continuously improved with a shorter gantry rotation time and greater pitch factor. However, for the 320-row ADCT scanner, the TR with a pitch factor of pitch factor of >1.0, it was approximately one half of the gantry rotation time. The maximum TR values of single- and dual-source helical acquisition modes for the 128-slice DSCT scanner were 0.138 (R/P=0.285/1.5) and 0.074s (R/P=0.285/3.2), and the maximum TR values of the 64×0.5- and 160×0.5-mm detector configurations of the helical acquisition modes for the 320-row ADCT scanner were 0.120 (R/P=0.275/1.375) and 0.195s (R/P=0.3/0.6), respectively. Because the TR of a CT scanner is not accurately depicted in the specifications of the individual scanner, appropriate acquisition conditions should be determined based on the actual TR measurement. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  11. Low dose prospective ECG-gated delayed enhanced dual-source computed tomography in reperfused acute myocardial infarction comparison with cardiac magnetic resonance

    International Nuclear Information System (INIS)

    Wang Rui; Zhang Zhaoqi; Xu Lei; Ma Qin; He Yi; Lu Dongxu; Yu Wei; Fan Zhanming

    2011-01-01

    Purpose: To determine whether prospective electrocardiogram (ECG)-gated delayed contrast-enhanced dual-source computed tomography (DCE-DSCT) can accurately delineate the extension of myocardial infarction (MI) compared with delayed enhanced cardiac MR (DE-MR). Material and methods: Eleven patients were examined using dual-source CT and cardiac MR in 2 weeks after a first reperfused MI. DCE-DSCT scan protocol was performed with prospective ECG-gating sequential scan model 7 min after contrast administration. In a 17-model, infarcted myocardium detected by DE-MR was categorized as transmural and subendocardial extension. Segment of infarcted location and graded transmurality were compared between DCE-MDCT and DE-MR. Results: In all eleven patients, diagnostic quality was obtained for depicting delayed enhanced myocardium. Agreement between DCE-DSCT and MR was good on myocardial segment based comparison (kappa = 0.85, p < 0.001), and on transmural and subendocardial infarction type comparison (kappa = 0.82, p < 0.001, kappa = 0.52, p < 0.001, respectively). CT value was higher on infarcted region than that of normal region (100.02 ± 9.57 HU vs. 72.63 ± 7.32 HU, p < 0.001). Radiation dose of prospectively ECG-gating protocol were 0.99 ± 0.08 mSv (0.82-1.19 mSv). Conclusions: Prospective ECG-gated DCE-DSCT can accurately assess the extension and the patterns of myocardial infarction with low radiation dose.

  12. Low dose prospective ECG-gated delayed enhanced dual-source computed tomography in reperfused acute myocardial infarction comparison with cardiac magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Wang Rui, E-mail: rui_wang1979@yahoo.cn [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Zhang Zhaoqi, E-mail: zhaoqi5000@vip.sohu.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Xu Lei, E-mail: leixu2001@hotmail.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Ma Qin, E-mail: tel1367@gmail.com [Department of Emergency, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); He Yi, E-mail: heyi139@sina.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Lu Dongxu, E-mail: larry.hi@163.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Yu Wei, E-mail: yuwei02@gmail.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China); Fan Zhanming, E-mail: fanzm120@tom.com [Department of Radiology, Beijing Anzhen Hospital, Capital Medical University, 100029 Beijing (China)

    2011-11-15

    Purpose: To determine whether prospective electrocardiogram (ECG)-gated delayed contrast-enhanced dual-source computed tomography (DCE-DSCT) can accurately delineate the extension of myocardial infarction (MI) compared with delayed enhanced cardiac MR (DE-MR). Material and methods: Eleven patients were examined using dual-source CT and cardiac MR in 2 weeks after a first reperfused MI. DCE-DSCT scan protocol was performed with prospective ECG-gating sequential scan model 7 min after contrast administration. In a 17-model, infarcted myocardium detected by DE-MR was categorized as transmural and subendocardial extension. Segment of infarcted location and graded transmurality were compared between DCE-MDCT and DE-MR. Results: In all eleven patients, diagnostic quality was obtained for depicting delayed enhanced myocardium. Agreement between DCE-DSCT and MR was good on myocardial segment based comparison (kappa = 0.85, p < 0.001), and on transmural and subendocardial infarction type comparison (kappa = 0.82, p < 0.001, kappa = 0.52, p < 0.001, respectively). CT value was higher on infarcted region than that of normal region (100.02 {+-} 9.57 HU vs. 72.63 {+-} 7.32 HU, p < 0.001). Radiation dose of prospectively ECG-gating protocol were 0.99 {+-} 0.08 mSv (0.82-1.19 mSv). Conclusions: Prospective ECG-gated DCE-DSCT can accurately assess the extension and the patterns of myocardial infarction with low radiation dose.

  13. High-pitch coronary CT angiography in dual-source CT during free breathing vs. breath holding in patients with low heart rates

    Energy Technology Data Exchange (ETDEWEB)

    Bischoff, Bernhard, E-mail: bernhard.bischoff@med.uni-muenchen.de [Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital Munich (Germany); DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, Munich (Germany); Meinel, Felix G. [Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital Munich (Germany); DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, Munich (Germany); Del Prete, Alessandra [Department of Radiology Magrassi-Lanzara, Second University of Naples, Naples (Italy); Reiser, Maximilian F.; Becker, Hans-Christoph [Institute for Clinical Radiology, Ludwig-Maximilians-University Hospital Munich (Germany); DZHK (German Centre for Cardiovascular Research), Partner Site Munich Heart Alliance, Munich (Germany)

    2013-12-01

    Background: Coronary CT angiography (CCTA) is usually performed during breath holding to reduce motion artifacts caused by respiration. However, some patients are not able to follow the breathing commands adequately due to deafness, hearing impairment, agitation or pulmonary diseases. The aim of this study was to evaluate the potential of high-pitch CCTA in free breathing patients when compared to breath holding patients. Methods: In this study we evaluated 40 patients (20 free breathing and 20 breath holding patients) with a heart rate of 60 bpm or below referred for CCTA who were examined on a 2nd generation dual-source CT system. Image quality of each coronary artery segment was rated using a 4-point grading scale (1: non diagnostic–4: excellent). Results: Mean heart rate during image acquisition was 52 ±5 bpm in both groups. There was no significant difference in mean image quality, slightly favoring image acquisition during breath holding (mean image quality score 3.76 ± 0.32 in breath holding patients vs. 3.61 ± 0.45 in free breathing patients; p = 0.411). Due to a smaller amount of injected contrast medium, there was a trend for signal intensity to be slightly lower in free breathing patients, but this was not statistically significant (435 ± 123 HU vs. 473 ± 117 HU; p = 0.648). Conclusion: In patients with a low heart rate who are not able to hold their breath adequately, CCTA can also be acquired during free breathing without substantial loss of image quality when using a high pitch scan mode in 2nd generation dual-source CT.

  14. Evaluation of dual-source parallel RF excitation for diffusion-weighted whole-body MR imaging with background body signal suppression at 3.0 T

    Energy Technology Data Exchange (ETDEWEB)

    Muertz, Petra, E-mail: petra.muertz@ukb.uni-bonn.de [Department of Radiology, University of Bonn (Germany); Kaschner, Marius, E-mail: marius.kaschner@ukb.uni-bonn.de [Department of Radiology, University of Bonn (Germany); Traeber, Frank, E-mail: frank.traeber@ukb.uni-bonn.de [Department of Radiology, University of Bonn (Germany); Kukuk, Guido M., E-mail: guido.kukuk@ukb.uni-bonn.de [Department of Radiology, University of Bonn (Germany); Buedenbender, Sarah M., E-mail: sarah_m_buedenbender@yahoo.de [Department of Radiology, University of Bonn (Germany); Skowasch, Dirk, E-mail: dirk.skowasch@ukb.uni-bonn.de [Department of Medicine, University of Bonn (Germany); Gieseke, Juergen, E-mail: juergen.gieseke@philips.com [Philips Healthcare, Best (Netherlands); Department of Radiology, University of Bonn (Germany); Schild, Hans H., E-mail: hans.schild@ukb.uni-bonn.de [Department of Radiology, University of Bonn (Germany); Willinek, Winfried A., E-mail: winfried.willinek@ukb.uni-bonn.de [Department of Radiology, University of Bonn (Germany)

    2012-11-15

    Purpose: To evaluate the use of dual-source parallel RF excitation (TX) for diffusion-weighted whole-body MRI with background body signal suppression (DWIBS) at 3.0 T. Materials and methods: Forty consecutive patients were examined on a clinical 3.0-T MRI system using a diffusion-weighted (DW) spin-echo echo-planar imaging sequence with a combination of short TI inversion recovery and slice-selective gradient reversal fat suppression. DWIBS of the neck (n = 5), thorax (n = 8), abdomen (n = 6) and pelvis (n = 21) was performed both with TX (2:56 min) and with standard single-source RF excitation (4:37 min). The quality of DW images and reconstructed inverted maximum intensity projections was visually judged by two readers (blinded to acquisition technique). Signal homogeneity and fat suppression were scored as 'improved', 'equal', 'worse' or 'ambiguous'. Moreover, the apparent diffusion coefficient (ADC) values were measured in muscles, urinary bladder, lymph nodes and lesions. Results: By the use of TX, signal homogeneity was 'improved' in 25/40 and 'equal' in 15/40 cases. Fat suppression was 'improved' in 17/40 and 'equal' in 23/40 cases. These improvements were statistically significant (p < 0.001, Wilcoxon signed-rank test). In five patients, fluid-related dielectric shading was present, which improved remarkably. The ADC values did not significantly differ for the two RF excitation methods (p = 0.630 over all data, pairwise Student's t-test). Conclusion: Dual-source parallel RF excitation improved image quality of DWIBS at 3.0 T with respect to signal homogeneity and fat suppression, reduced scan time by approximately one-third, and did not influence the measured ADC values.

  15. The value of coronary artery calcium score assessed by dual-source computed tomography coronary angiography for predicting presence and severity of coronary artery disease

    International Nuclear Information System (INIS)

    Almasi, Alireza; Pouraliakbar, Hamidreza; Sedghian, Ahmad; Karimi, Mohammad Ali; Firouzi, Ata; Tehrai, Mahmood

    2014-01-01

    Measuring coronary artery calcium score (CACS) using a dual-source CT scanner is recognized as a major indicator for assessing coronary artery disease. The present study aimed to validate the clinical significance of CACS in predicting coronary artery stenosis and its severity. This prospective study was conducted on 202 consecutive patients who underwent both conventional coronary angiography and dual-source (256-slice) computed tomography coronary angiography (CTA) for any reason in our cardiac imaging center from March to September 2013. CACS was measured by Agatston algorithm on non-enhanced CT. The severity of coronary artery disease was assessed by Gensini score on conventional angiography. There was a significant relationship between the number of diseased coronary vessels and mean calcium score, i.e. the mean calcium score was 202.25±450.06 in normal coronary status, 427.50±607.24 in single-vessel disease, 590.03±511.34 in two-vessel disease, and 953.35±1023.45 in three-vessel disease (p<0.001). There was a positive association between calcium score and Gensini score (r=0.636, p<0.001). In a linear regression model, calcium score was a strong determinant of the severity of coronary artery disease. Calcium scoring had an acceptable value for discriminating coronary disease from normal condition with optimal cutoff point of 350, yielding a sensitivity and specificity of 83% and 70%, respectively. Our study confirmed the strong relationship between the coronary artery calcium score and the presence and severity of stenosis in coronary arteries assessed by both the number of diseased coronary vessels and also by the Gnesini score

  16. Thoraco-abdominal high-pitch dual-source CT angiography: Experimental evaluation of injection protocols with an anatomical human vascular phantom

    Energy Technology Data Exchange (ETDEWEB)

    Puippe, Gilbert D., E-mail: gilbert.puippe@usz.ch [Institute for Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland Raemistrasse 100, CH-8091 Zurich (Switzerland); Winklehner, Anna [Institute for Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland Raemistrasse 100, CH-8091 Zurich (Switzerland); Hasenclever, Peter; Plass, André [Division of Cardiac and Vascular Surgery, University Hospital Zurich, Switzerland Raemistrasse 100, CH-8091 Zurich (Switzerland); Frauenfelder, Thomas; Baumueller, Stephan [Institute for Diagnostic and Interventional Radiology, University Hospital Zurich, Switzerland Raemistrasse 100, CH-8091 Zurich (Switzerland)

    2012-10-15

    Objective: To experimentally evaluate three different contrast injection protocols at thoraco-abdominal high-pitch dual-source computed tomography angiography (CTA), with regard to level and homogeneity of vascular enhancement at different cardiac outputs. Materials and methods: A uniphasic, a biphasic as well as an individually tailored contrast protocol were tested using a human vascular phantom. Each protocol was scanned at 5 different cardiac outputs (3–5 L/min, steps of 0.5 L/min) using an extracorporeal cardiac pump. Vascular enhancement of the thoraco-abdominal aorta was measured every 5 cm. Overall mean enhancement of each protocol and mean enhancement for each cardiac output within each protocol were calculated. Enhancement homogeneity along the z-axis was evaluated for each cardiac output and protocol. Results: Overall mean enhancement was significantly higher in the uniphasic than in the other two protocols (all p < .05), whereas the difference between the biphasic and tailored protocol was not significant (p = .76). Mean enhancement among each of the 5 cardiac outputs within each protocol was significantly different (all p < .05). Only within the tailored protocol mean enhancement differed not significantly at cardiac outputs of 3.5 L/min vs. 5 L/min (484 ± 25 HU vs. 476 ± 19 HU, p = .14) and 4 vs. 5 L/min (443 ± 49 HU vs. 476 ± 19 HU, p = .05). Both, uniphasic and tailored protocol yielded homogenous enhancement at all cardiac outputs, whereas the biphasic protocol failed to achieve homogenous enhancement. Conclusion: This phantom study suggests that diagnostic and homogenous enhancement at thoraco-abdominal high-pitch dual-source CTA is feasible with either a uniphasic or an individually tailored contrast protocol.

  17. Techno-economic study of a distributed hybrid renewable energy system supplying electrical power and heat for a rural house in China

    Science.gov (United States)

    Yuan, Jindou; Xu, Jinliang; Wang, Yaodong

    2018-03-01

    Energy saving and emission reduction have become targets for modern society due to the potential energy crisis and the threat of climate change. A distributed hybrid renewable energy system (HRES) consists of photovoltaic (PV) arrays, a wood-syngas combined heat and power generator (CHP) and back-up batteries is designed to power a typical semi-detached rural house in China which aims to meet the energy demand of a house and to reduce greenhouse gas emissions from the use of fossil fuels. Based on the annual load information of the house and the local meteorological data including solar radiation, air temperature, etc., a system model is set up using HOMER software and is used to simulate all practical configurations to carry out technical and economic evaluations. The performance of the whole HRES system and each component under different configurations are evaluated. The optimized configuration of the system is found

  18. Optimal design approach for heating irregular-shaped objects in three-dimensional radiant furnaces using a hybrid genetic algorithm-artificial neural network method

    Science.gov (United States)

    Darvishvand, Leila; Kamkari, Babak; Kowsary, Farshad

    2018-03-01

    In this article, a new hybrid method based on the combination of the genetic algorithm (GA) and artificial neural network (ANN) is developed to optimize the design of three-dimensional (3-D) radiant furnaces. A 3-D irregular shape design body (DB) heated inside a 3-D radiant furnace is considered as a case study. The uniform thermal conditions on the DB surfaces are obtained by minimizing an objective function. An ANN is developed to predict the objective function value which is trained through the data produced by applying the Monte Carlo method. The trained ANN is used in conjunction with the GA to find the optimal design variables. The results show that the computational time using the GA-ANN approach is significantly less than that of the conventional method. It is concluded that the integration of the ANN with GA is an efficient technique for optimization of the radiant furnaces.

  19. Hybrid friction diffusion bonding of 316L stainless steel tube-to-tube sheet joints for coil-wound heat exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Haneklaus, Nils; Cionea, Cristian; Reuven, Rony; Frazer, David; Hosemann, Peter; Peterson, Per F. [Dept of Nuclear Engineering, University of California, Berkeley (United States)

    2016-11-15

    Hybrid friction diffusion bonding (HFDB) is a solid-state bonding process first introduced by Helmholtz-Zentrum Geesthacht to join aluminum tube-to-tube sheet joints of Coil-wound heat exchangers (CWHE). This study describes how HFDB was successfully used to manufacture 316L test samples simulating tube-to-tube sheet joints of stainless steel CWHE for molten salt coolants as foreseen in several advanced nuclear- and thermal solar power plants. Engineering parameters of the test sample fabrication are presented and results from subsequent non-destructive vacuum decay leak testing and destructive tensile pull-out testing are discussed. The bonded areas of successfully fabricated samples as characterized by tube rupture during pull-out tensile testing, were further investigated using optical microscopy and scanning electron microscopy including electron backscatter diffraction.

  20. Coordination of Heat Pumps, Electric Vehicles and AGC for Efficient LFC in a Smart Hybrid Power System via SCA-Based Optimized FOPID Controllers

    Directory of Open Access Journals (Sweden)

    Rahmat Khezri

    2018-02-01

    Full Text Available Due to the high price of fossil fuels, the increased carbon footprint in conventional generation units and the intermittent functionality of renewable units, alternative sources must contribute to the load frequency control (LFC of the power system. To tackle the challenge, dealing with controllable loads, the ongoing study aims at efficient LFC in smart hybrid power systems. To achieve this goal, heat pumps (HPs and electric vehicles (EVs are selected as the most effective controllable loads to contribute to the LFC issue. In this regard, the EVs can be controlled in a bidirectional manner as known charging and discharging states under a smart structure. In addition, regarding the HPs, the power consumption is controllable. As the main task, this paper proposes a fractional order proportional integral differential (FOPID controller for coordinated control of power consumption in HPs, the discharging state in EVs and automatic generation control (AGC. The parameters of the FOPID controllers are optimized simultaneously by the sine cosine algorithm (SCA, which is a new method for optimization problems. In the sequel, four scenarios, including step and random load changes, aggregated intermittent generated power from wind turbines, a random load change scenario and a sensitivity analysis scenario, are selected to demonstrate the efficiency of the proposed SCA-based FOPID controllers in a hybrid two-area power system.

  1. Experimental pressure drop and heat transfer in square array rod bundle for fusion-fission hybrid system

    Energy Technology Data Exchange (ETDEWEB)

    Shamim, J.A.; Bhowmik, P.K. [Seoul National Univ., Gwanak Gu, Seoul (Korea, Republic of); Suh, K.Y., E-mail: kysuh@snu.ac.kr [Seoul National Univ., Gwanak Gu, Seoul (Korea, Republic of); PhiloSophia Inc., Gwanak Gu, Seoul (Korea, Republic of)

    2014-07-01

    The effects of grid spacer flow restriction on pressure drop are evaluated experimentally for a wide range of flow rates. The results are compared against predictions by using most well known correlations. The convective heat transfer coefficients are evaluated using ANSYS 12.1 for a 3x3 rod bundle for pure water and alumina nanofluid. It is observed that the experimental pressure drop falls within 10%~20% of the predictions. Heat transfer of the 4% alumina nanofluid increases about 18% over pure water under the same inlet flow condition. (author)

  2. Experimental pressure drop and heat transfer in square array rod bundle for fusion-fission hybrid system

    International Nuclear Information System (INIS)

    Shamim, J.A.; Bhowmik, P.K.; Suh, K.Y.

    2014-01-01

    The effects of grid spacer flow restriction on pressure drop are evaluated experimentally for a wide range of flow rates. The results are compared against predictions by using most well known correlations. The convective heat transfer coefficients are evaluated using ANSYS 12.1 for a 3x3 rod bundle for pure water and alumina nanofluid. It is observed that the experimental pressure drop falls within 10%~20% of the predictions. Heat transfer of the 4% alumina nanofluid increases about 18% over pure water under the same inlet flow condition. (author)

  3. Acceleration of calculation of nuclear heating distributions in ITER toroidal field coils using hybrid Monte Carlo/deterministic techniques

    International Nuclear Information System (INIS)

    Ibrahim, Ahmad M.; Polunovskiy, Eduard; Loughlin, Michael J.; Grove, Robert E.; Sawan, Mohamed E.

    2016-01-01

    Highlights: • Assess the detailed distribution of the nuclear heating among the components of the ITER toroidal field coils. • Utilize the FW-CADIS method to dramatically accelerate the calculation of detailed nuclear analysis. • Compare the efficiency and reliability of the FW-CADIS method and the MCNP weight window generator. - Abstract: Because the superconductivity of the ITER toroidal field coils (TFC) must be protected against local overheating, detailed spatial distribution of the TFC nuclear heating is needed to assess the acceptability of the designs of the blanket, vacuum vessel (VV), and VV thermal shield. Accurate Monte Carlo calculations of the distributions of the TFC nuclear heating are challenged by the small volumes of the tally segmentations and by the thick layers of shielding provided by the blanket and VV. To speed up the MCNP calculation of the nuclear heating distribution in different segments of the coil casing, ground insulation, and winding packs of the ITER TFC, the ITER Organization (IO) used the MCNP weight window generator (WWG). The maximum relative uncertainty of the tallies in this calculation was 82.7%. In this work, this MCNP calculation was repeated using variance reduction parameters generated by the Oak Ridge National Laboratory AutomateD VAriaNce reducTion Generator (ADVANTG) code and both MCNP calculations were compared in terms of computational efficiency and reliability. Even though the ADVANTG MCNP calculation used less than one-sixth of the computational resources of the IO calculation, the relative uncertainties of all the tallies in the ADVANTG MCNP calculation were less than 6.1%. The nuclear heating results of the two calculations were significantly different by factors between 1.5 and 2.3 in some of the segments of the furthest winding pack turn from the plasma neutron source. Even though the nuclear heating in this turn may not affect the ITER design because it is much smaller than the nuclear heating in the

  4. Acceleration of calculation of nuclear heating distributions in ITER toroidal field coils using hybrid Monte Carlo/deterministic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Ibrahim, Ahmad M., E-mail: ibrahimam@ornl.gov [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Polunovskiy, Eduard; Loughlin, Michael J. [ITER Organization, Route de Vinon Sur Verdon, 13067 St. Paul Lez Durance (France); Grove, Robert E. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Sawan, Mohamed E. [University of Wisconsin-Madison, 1500 Engineering Dr., Madison, WI 53706 (United States)

    2016-11-01

    Highlights: • Assess the detailed distribution of the nuclear heating among the components of the ITER toroidal field coils. • Utilize the FW-CADIS method to dramatically accelerate the calculation of detailed nuclear analysis. • Compare the efficiency and reliability of the FW-CADIS method and the MCNP weight window generator. - Abstract: Because the superconductivity of the ITER toroidal field coils (TFC) must be protected against local overheating, detailed spatial distribution of the TFC nuclear heating is needed to assess the acceptability of the designs of the blanket, vacuum vessel (VV), and VV thermal shield. Accurate Monte Carlo calculations of the distributions of the TFC nuclear heating are challenged by the small volumes of the tally segmentations and by the thick layers of shielding provided by the blanket and VV. To speed up the MCNP calculation of the nuclear heating distribution in different segments of the coil casing, ground insulation, and winding packs of the ITER TFC, the ITER Organization (IO) used the MCNP weight window generator (WWG). The maximum relative uncertainty of the tallies in this calculation was 82.7%. In this work, this MCNP calculation was repeated using variance reduction parameters generated by the Oak Ridge National Laboratory AutomateD VAriaNce reducTion Generator (ADVANTG) code and both MCNP calculations were compared in terms of computational efficiency and reliability. Even though the ADVANTG MCNP calculation used less than one-sixth of the computational resources of the IO calculation, the relative uncertainties of all the tallies in the ADVANTG MCNP calculation were less than 6.1%. The nuclear heating results of the two calculations were significantly different by factors between 1.5 and 2.3 in some of the segments of the furthest winding pack turn from the plasma neutron source. Even though the nuclear heating in this turn may not affect the ITER design because it is much smaller than the nuclear heating in the

  5. Investigation of heat transfer and flow using ribs within gas turbine blade cooling passage: Experimental and hybrid LES/RANS modeling

    Science.gov (United States)

    Kumar, Sourabh

    Gas turbines are extensively used for aircraft propulsion, land based power generation and various industrial applications. Developments in innovative gas turbine cooling technology enhance the efficiency and power output, with an increase in turbine rotor inlet temperatures. These advancements of turbine cooling have allowed engine design to exceed normal material temperature limits. For internal cooling design, techniques for heat extraction from the surfaces exposed to hot stream are based on the increase of heat transfer areas and on promotion of turbulence of the cooling flow. In this study, it is obtained by casting repeated continuous V and broken V shaped ribs on one side of the two pass square channel into the core of blade. Despite extensive research on ribs, only few papers have validated the numerical data with experimental results in two pass channel. In the present study, detailed experimental investigation is carried out for two pass square channels with 180° turn. Detailed heat transfer distribution occurring in the ribbed passage is reported for steady state experiment. Four different combinations of 60° and Broken 60° V ribs in channel are considered. Thermocouples are used to obtain the temperature on the channel surface and local heat transfer coefficients are obtained for various Reynolds numbers, within the turbulent flow regime. Area averaged data are calculated in order to compare the overall performance of the tested ribbed surface and to evaluate the degree of heat transfer enhancement induced by the ribs with. Flow within the channels is characterized by heat transfer enhancing ribs, bends, rotation and buoyancy effects. Computational Fluid Dynamics (CFD) simulations were carried out for the same geometries using different turbulence models such as k-o Shear stress transport (SST) and Reynolds stress model (RSM). These CFD simulations were based on advanced computing in order to improve the accuracy of three dimensional metal

  6. Design and Preparation of RF System for the Lower Hybrid Fast Wave Heating and Current Drive Research on VEST

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sun Ho; Jeong, Seung Ho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, Hyun Woo; Lee, Byung Je [Kwang Woon University, Chuncheon (Korea, Republic of); Jo, Jong Gab; Lee, Hyun Young; Hwang, Yong Seok [Seoul National University, Seoul (Korea, Republic of)

    2015-10-15

    Continuous current drive is one of the key issues for tokamak to be a commercial fusion reactor. As a part of new and efficient current drive concept research by using a Lower Hybrid Fast Wave (LHFW), the experimental study is planned on Versatile Experiment Spherical Torus (VEST) and a RF system is being developed in collaboration with Kwang Woon University (KWU), Korea Accelerator Plasma Research Association (KAPRA) and Seoul National University (SNU). The LHFW RF system includes UHF band klystron, inter-digital antenna, RF diagnostics and power transmission sub components such as circulator, DC breaker, vacuum feed-thru. The design and preparation status of the RF system will be presented in the meeting in detail. A RF system has been designed and prepared for the experimental study of efficient current drive by using Lower Hybrid Fast Wave. Overall LHFW RF system including diagnostics is designed to deliver about 10 kW in UHF band. And the key hardware components including klystron and antenna are being prepared and designed through the collaboration with KWU, KAPRA and SNU.

  7. Lower hybrid current drive and heating experiments at the 1 MW rf power level on Alcator C

    International Nuclear Information System (INIS)

    Porkolab, M.; Lloyd, B.; Schuss, J.J.

    1983-07-01

    Lower hybrid current drive experiments were carried out in the density range 1.0 x 10 13 less than or equal to anti n(cm -3 ) less than or equal to 1.0 x 10 14 , at magnetic fields 6.0 less than or equal to B(T) less than or equal to 10. Using one 16 waveguide array, plasma currents of 150 to 200 kA have been driven by rf powers up to 600 kW for times greater than 100 msec at anti n/sub e/ up to 5 x 10 13 cm -3 . With two arrays at anti n/sub e/ approx. = 4.3 x 10 13 cm -3 at B/sub T/ = 10 T, plasma currents of 160 kA have been maintained by the rf power for 300 msec with zero loop voltage and constant internal inductance

  8. Photoelectrochemical behavior of Al{sub x}In{sub 1−x}N thin films grown by plasma-assisted dual source reactive evaporation

    Energy Technology Data Exchange (ETDEWEB)

    Alizadeh, M., E-mail: alizadeh_kozerash@yahoo.com; Ganesh, V.; Pandikumar, A.; Goh, B.T.; Azianty, S.; Huang, N.M.; Rahman, S.A., E-mail: saadah@um.edu.my

    2016-06-15

    In this work the dependence of photoelectrochemical (PEC) behavior of Al{sub x}In{sub 1−x}N (0.48 ≤x ≤ 0.66) thin films grown by plasma-assisted dual source reactive evaporation, on the plasma dynamics and the alloys properties was studied. The influence of nitrogen flow rate on the compositional, morphological, structural and optical properties of the as-prepared films were investigated using X-ray photoelectron spectroscopy (XPS), Field emission scanning electron microscopy (FESEM), micro Raman spectroscopy and UV–vis spectroscopy. The PEC study of the as-grown Al{sub x}In{sub 1−x}N thin films targeted for water splitting application were performed in the presence of simulated solar irradiation of AM 1.5G (100 mW/cm{sup 2}). The PEC results revealed that the photocurrent for the Al{sub x}In{sub 1−x}N thin film grown at nitrogen flow rate of 80 sccm is ∼10-fold higher than the dark current. From the Mott–Schottky (MS) plots it was deduced that by increasing N{sub 2} flow rate up to 80 sccm, the flat band potential shifts toward more negative values. The good photoelectrochemical behavior of Al{sub x}In{sub 1−x}N thin films showed that this material could be a potential candidate for PEC water splitting. - Highlights: • Al{sub x}In{sub 1−x}N films were grown by Plasma-aided dual source reactive evaporation. • Effect of nitrogen flow rate on the films properties was investigated. • The band gap of the films decreased from 2.33 to 1.92 eV. • A good photoelectrochemical behavior of the Al{sub x}In{sub 1−x}N thin films was shown. • The photocurrent for the Al{sub 0.55}In{sub 0.45}N films is ∼10-fold higher than dark current.

  9. Optimized imaging quality and radiation dose for coronary artery angiography using 128-slice, dual-source Flash Spiral CT under the natural heart rate

    International Nuclear Information System (INIS)

    Xue Yuejun; Qian Nong; Shao Yanhui; Pan Changjie; Rong Weiliang; Xu Yiqun; Tao Zhiwei

    2011-01-01

    Objective: To compare the quality and radiation doses of coronary artery angiography under the natural heart rate condition between Flash spiral heart mode and prospective electrocardiogram- triggering sequence mode using dual-source, in order to choose personalized low doses of coronary artery scanning mode. Methods: Sixty patients who underwent coronary angiography (CTA) on a 128-slice, dual- source CT scanner were divided into 2 group i.e, group A (27 cases) and group B (33 cases). Flash spiral heart scan mode was employed for group A. Inclusion criteria included: heart rate 75 bpm), date acquisition was set at 30%-50% of the R-R interval. (3) At the arrhythmias, premature beat, fibrillation atrial, date acquisition was set at 20%-90% of the R-R interval. In both groups, patients with a BMI ≥ 25.0 kg/m 2 were examined with a tube voltage of 120 kV, while the other patients with a BMI 2 were examined with a tube voltage of 100 kV. The BMI was (24.6±1.0) kg/m 2 in group A, while that was (24.6±0.9) kg/m 2 in group B. In both groups, all images were transferred to the workstation for further processing and analysis. The imaging quality of coronary artery segments and the radiation dose were compared with t test. Results: A total of 336 coronary artery segments were evaluated in group A and 412 segments were evaluated in group B. The imaging quality of coronary artery segments were scored. Excellent or good was achieved in 98.2% (330 of 336) artery segments in group A, and that was 98.1% (404 of 412) in group B. There was no statistical difference in imaging quality between the two groups (t=0.513, P=0.608). The average effective dose was (0.74±0.29) mSv in group A, whereas that was (3.67± 1.37) mSv in group B. There was a significant difference between the two groups (t=-10.858, P= 0.000). Conclusions: The personalized low doses coronary artery scanning mode can substantially reduce radiation damage while preserving good imaging quality. (authors)

  10. From first to latest imaging technology: Revisiting the first mummy investigated with X-ray in 1896 by using dual-source computed tomography.

    Science.gov (United States)

    Zesch, Stephanie; Panzer, Stephanie; Rosendahl, Wilfried; Nance, John W; Schönberg, Stefan O; Henzler, Thomas

    2016-01-01

    The aim of this study was to systematically reinvestigate the first human mummy that was ever analyzed with X-ray imaging in 1896, using dual-source computed tomography (DSCT) in order to compare the earliest and latest imaging technologies, to estimate preservation, age at death, sex, anatomical variants, paleopathological findings, mummification, embalming and wrapping of the child mummy from ancient Egypt. Radiocarbon dating was used to determine the mummy's age and to specify the child's living period in the Egyptian chronology. The ancient Egyptian child mummy is kept in the Senckenberg Museum of Natural History in Frankfurt am Main, Germany. An accelerator mass spectrometer (MICADAS) was used for radiocarbon dating. DSCT was performed using a 2 × 64 slice dual-source CT system (Siemens Healthineers, Forchheim, Germany). A thorough visual examination of the mummy, a systematic radiological evaluation of the DICOM datasets, and established methods in physical anthropology were applied to assess the bio-anthropological data and the post mortem treatment of the body. Radiocarbon dating yielded a calibrated age between 378 and 235 cal BC (95.4% confidence interval), corresponding with the beginning of the Ptolemaic period. The mummy was a male who was four to five years old at the time of death. Remnants of the brain and inner organs were preserved by the embalmers, which is regularly observed in ancient Egyptian child mummies. Skin tissue, inner organs, tendons and/or musculature, cartilage, nerves and vasculature could be identified on the DSCT dataset. The dental health of the child was excellent. Anatomical variants and pathological defects included a congenital Pectus excavatum deformity, hepatomegaly, Harris lines, and longitudinal clefts in the ventral cortices of both femora. Our results highlight the enormous progress achieved form earliest to latest imaging technology for advanced mummy research using the first human mummy investigated with X

  11. From first to latest imaging technology: Revisiting the first mummy investigated with X-ray in 1896 by using dual-source computed tomography

    International Nuclear Information System (INIS)

    Zesch, Stephanie; Panzer, Stephanie; Rosendahl, Wilfried; Nance, John W. Jr.; Schönberg, Stefan O.; Henzler, Thomas

    2016-01-01

    The aim of this study was to systematically reinvestigate the first human mummy that was ever analyzed with X-ray imaging in 1896, using dual-source computed tomography (DSCT) in order to compare the earliest and latest imaging technologies, to estimate preservation, age at death, sex, anatomical variants, paleopathological findings, mummification, embalming and wrapping of the child mummy from ancient Egypt. Radiocarbon dating was used to determine the mummy’s age and to specify the child’s living period in the Egyptian chronology. The ancient Egyptian child mummy is kept in the Senckenberg Museum of Natural History in Frankfurt am Main, Germany. An accelerator mass spectrometer (MICADAS) was used for radiocarbon dating. DSCT was performed using a 2 × 64 slice dual-source CT system (Siemens Healthineers, Forchheim, Germany). A thorough visual examination of the mummy, a systematic radiological evaluation of the DICOM datasets, and established methods in physical anthropology were applied to assess the bio-anthropological data and the post mortem treatment of the body. Radiocarbon dating yielded a calibrated age between 378 and 235 cal BC (95.4% confidence interval), corresponding with the beginning of the Ptolemaic period. The mummy was a male who was four to five years old at the time of death. Remnants of the brain and inner organs were preserved by the embalmers, which is regularly observed in ancient Egyptian child mummies. Skin tissue, inner organs, tendons and/or musculature, cartilage, nerves and vasculature could be identified on the DSCT dataset. The dental health of the child was excellent. Anatomical variants and pathological defects included a congenital Pectus excavatum deformity, hepatomegaly, Harris lines, and longitudinal clefts in the ventral cortices of both femora. Our results highlight the enormous progress achieved form earliest to latest imaging technology for advanced mummy research using the first human mummy investigated with X

  12. Quantitative parameters to compare image quality of non-invasive coronary angiography with 16-slice, 64-slice and dual-source computed tomography

    International Nuclear Information System (INIS)

    Burgstahler, Christof; Reimann, Anja; Brodoefel, Harald; Tsiflikas, Ilias; Thomas, Christoph; Heuschmid, Martin; Daferner, Ulrike; Drosch, Tanja; Schroeder, Stephen; Herberts, Tina

    2009-01-01

    Multi-slice computed tomography (MSCT) is a non-invasive modality to visualize coronary arteries with an overall good image quality. Improved spatial and temporal resolution of 64-slice and dual-source computed tomography (DSCT) scanners are supposed to have a positive impact on diagnostic accuracy and image quality. However, quantitative parameters to compare image quality of 16-slice, 64-slice MSCT and DSCT are missing. A total of 256 CT examinations were evaluated (Siemens, Sensation 16: n=90; Siemens Sensation 64: n=91; Siemens Definition: n=75). Mean Hounsfield units (HU) were measured in the cavum of the left ventricle (LV), the ascending aorta (Ao), the left ventricular myocardium (My) and the proximal part of the left main (LM), the left anterior descending artery (LAD), the right coronary artery (RCA) and the circumflex artery (CX). Moreover, the ratio of intraluminal attenuation (HU) to myocardial attenuation was assessed for all coronary arteries. Clinical data [body mass index (BMI), gender, heart rate] were accessible for all patients. Mean attenuation (CA) of the coronary arteries was significantly higher for DSCT in comparison to 64- and 16-slice MSCT within the RCA [347±13 vs. 254±14 (64-MSCT) vs. 233±11 (16-MSCT) HU], LM (362±11/275 ± 12/262±9), LAD (332±17/248±19/219±14) and LCX (310±12/210±13/221±10, all p<0.05), whereas there was no significant difference between DSCT and 64-MSCT for the LV, the Ao and My. Heart rate had a significant impact on CA ratio in 16-slice and 64-slice CT only (p<0.05). BMI had no impact on the CA ratio in DSCT only (p<0.001). Improved spatial and temporal resolution of dual-source CT is associated with better opacification of the coronary arteries and a better contrast with the myocardium, which is independent of heart rate. In comparison to MSCT, opacification of the coronary arteries at DSCT is not affected by BMI. The main advantage of DSCT lies with the heart rate independency, which might have a

  13. Hybrid joining of polyamide and hydrogenated acrylonitrile butadiene rubber through heat-resistant functional layer of silane coupling agent

    Energy Technology Data Exchange (ETDEWEB)

    Sang, Jing; Sato, Riku [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Aisawa, Sumio, E-mail: aisawa@iwate-u.ac.jp [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Hirahara, Hidetoshi [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Mori, Kunio [Department of Frontier Materials and Function Engineering, Graduate School of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551 (Japan); Sulfur Chemical Institute, 210, Collabo MIU, 4-3-5, Ueda, Morioka 020-0066 (Japan)

    2017-08-01

    Highlights: • We modify PA6 surface using silane coupling agent layer of APTMS to link HNBR. • APTMS greatly improved heat resistance of PA6 from 153 °C up to 325 °C. • A PA6/HNBR joined body was obtained, and it exhibits high adhesion strength with cohesive failure. • Chemical structures of the adhesion interfaces of PA6/HNBR were confirmed by Nano-IR. - Abstract: A simple, direct adhesion method was developed to join polyamide (PA6) to hydrogenated acrylonitrile butadiene rubber (HNBR) by grafting a functional layer of a silane coupling agent on plasma functionalized PA6 surfaces. The functional layer of the silane coupling agent was prepared using a self-assembly method, which greatly improved the heat resistance of PA6 from 153 °C up to 325 °C and the resulting PA6/HNBR joints showed excellent adhesion properties with cohesive failure between PA6 and HNBR. X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and nanoscale infrared microscopy and chemical imaging (Nano-IR, AFM-IR) were employed to characterize the surfaces and interfaces. The Nano-IR analysis method was employed for the first time to analyze the chemical structures of the adhesion interfaces between different materials and to establish the interface formation mechanism. This study is of significant value for interface research and the study of adhesion between resins and rubbers. There is a promising future for heat-resistant functional layers on resin surfaces, with potential application in fuel hose composite materials for the automotive and aeronautical industries.

  14. Suppression of tungsten accumulation during ELMy H-mode by lower hybrid wave heating in the EAST tokamak

    Directory of Open Access Journals (Sweden)

    L. Zhang

    2017-08-01

    Full Text Available EAST tokamak has been equipped with upper tungsten divertor since 2014. The tungsten accumulation has been often observed in NBI-heated H-mode discharges suggesting deleterious tungsten confinement in the plasma core. It causes not only H-L back transition but also plasma disruption in several discharges. Suppression of the tungsten accumulation is therefore the most important issue in EAST to achieve a long pulse H-mode discharge. In order to study the tungsten behavior in the long pulse discharge, tungsten spectra have been measured at 20–140Å. The tungsten density, nw, is evaluated from the intensity of tungsten unresolved transition array (W-UTA in a wavelength range of 45–70Å which is composed of several ionization stages of tungsten, e.g. W27+-W45+ at Te0∼2.5keV. It is found that the tungsten accumulation can be suppressed when the 4.6GHz LHW with PLHW∼0.8MW is superimposed on the NBI phase (PNBI= 1.9MW. During the superimposed phase the ELM frequency, fELM, increases from ∼30Hz to ∼60Hz and the tungsten density is halved compared to the NBI-heated discharge. The H-mode discharge can be thus steadily sustained for longer period. It is found that the nw is a large function of the ratio of LHW power to the total injection power, PLHW/(PLHW+PNBI, and the nw can be reduced, at least, in an order of magnitude smaller than that in NBI-heated discharges at PLHW/(PLHW+PNBI≥0.8. The result strongly suggests a possible way toward the steady H-mode discharge.

  15. Heat transfer in a spent fuel pool concept containing PWR, Hybrid ADS-Fission, and VHTR spent fuels

    Energy Technology Data Exchange (ETDEWEB)

    Faria, Fernando P.; Cardoso, Fabiano; Salomé, Jean A.D.; Velasquez, Carlos E.; Pereira, Claubia, E-mail: fernandopereirabh@gmail.com, E-mail: fabinuclear@yahoo.com.br, E-mail: jadsalome@yahoo.com.br, E-mail: carlosvelcab@hotmail.com, E-mail: claubia@nuclear.ufmg.br [Universidade Federal de Minas Gerais, Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear

    2017-07-01

    Thermal evaluation under wet storage conditions of spent fuels (SF) of the types UO{sub 2} discharged from Pressurized Water Reactor (PWR) and Very High-temperature Reactor (VHTR), and (Th,TRU)O{sub 2} from Accelerator-Driven Subcritical Reactor System (ADS) and VHTR are presented. The analyzes are in the absence of an external cooling system of the pool, and the goal is to compare the water boiling time of the pool storing these different types of SF, at time t=0 year after reactor discharge. Two techniques were implemented. In the first one, all the materials of the fuel elements are considered. In the second, the SF is treated as holes inside the pool, assuming the heat transfer directly from the SF to the water. Results from first technique show that the boiling time (T{sub b}) ranged from 23 minutes for (Th,TRU)O{sub 2} from VHTR to 3 hours for UO{sub 2} from VHTR, while for the second technique, T{sub b} ranged from 10 minutes for (Th,TRU)O{sub 2} from VHTR to 2.7 hours for UO{sub 2} from VHTR. The discrepancies between Tb from both techniques reveal that the pathways considered for the heat transfer are crucial to the results. The thermal studies used the module CFX of the ANSYS Workbench 16.2 - student version. (author)

  16. Hybrid joining of polyamide and hydrogenated acrylonitrile butadiene rubber through heat-resistant functional layer of silane coupling agent

    Science.gov (United States)

    Sang, Jing; Sato, Riku; Aisawa, Sumio; Hirahara, Hidetoshi; Mori, Kunio

    2017-08-01

    A simple, direct adhesion method was developed to join polyamide (PA6) to hydrogenated acrylonitrile butadiene rubber (HNBR) by grafting a functional layer of a silane coupling agent on plasma functionalized PA6 surfaces. The functional layer of the silane coupling agent was prepared using a self-assembly method, which greatly improved the heat resistance of PA6 from 153 °C up to 325 °C and the resulting PA6/HNBR joints showed excellent adhesion properties with cohesive failure between PA6 and HNBR. X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and nanoscale infrared microscopy and chemical imaging (Nano-IR, AFM-IR) were employed to characterize the surfaces and interfaces. The Nano-IR analysis method was employed for the first time to analyze the chemical structures of the adhesion interfaces between different materials and to establish the interface formation mechanism. This study is of significant value for interface research and the study of adhesion between resins and rubbers. There is a promising future for heat-resistant functional layers on resin surfaces, with potential application in fuel hose composite materials for the automotive and aeronautical industries.

  17. Evaluation of the heat transfer in a geological repository concept containing PWR, VHTR and hybrid ads-fission spent fuels

    Energy Technology Data Exchange (ETDEWEB)

    Jonusan, Raoni A.S.; Pereira, Fernando; Velasquez, Carlos E.; Salome, Jean A.D.; Cardoso, Fabiano; Pereira, Claubia; Fortini, Angela, E-mail: claubia@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear

    2017-11-01

    The investigation of the thermal behavior of spent fuel (SF) materials is essential to determining appropriate potential sites to accommodate geological repositories as well as the design of canisters, considering their potential risk to people health and of environmental contamination. This work presents studies of the temperature in a canister containing spent fuels discharged from Pressurized Water Reactor (PWR), Very High-Temperature Reactor (VHTR) and Accelerator-Driven Subcritical Reactor System (ADS) reactor systems in a geological repository concept. The thermal analyses were performed with the software ANSYS, which is widely used to solve engineering problems through the Finite Element Method. The ANSYS Transient Thermal module was used. The spent nuclear fuels were set as heat sources using data of previous studies derived from decay heat curves. The studies were based on comparison of the mean temperature on a canister surface along the time under geological disposal conditions, for a same amount of each type of spent nuclear fuel evaluated. The results conclude that fuels from VHTR and ADS systems are inappropriate to be disposed in a standardized PWR canister, demanding new studies to determine the optimal amount of spent fuel and new internal canister geometries. It is also possible to conclude that the hypothetical situation of a single type of canister being used to accommodate different types of spent nuclear fuels is not technically feasible. (author)

  18. Diagnostic performance of dual-source CT coronary angiography with and without heart rate control: Systematic review and meta-analysis

    International Nuclear Information System (INIS)

    Li, M.; Zhang, G.-M.; Zhao, J.-S.; Jiang, Z.-W.; Peng, Z.-H.; Jin, Z.-T.; Sun, G.

    2014-01-01

    Aim: To investigate the diagnostic accuracy of dual-source computed tomography (DSCT) coronary angiography with and without the application of a β-blocker. Materials and methods: An exact binomial rendition of the bivariate mixed-effects regression model was used to synthesize diagnostic test data. Results: The pooled sensitivity at the patient level was 0.98 [95% confidence intervals (CI): 0.97–0.99], and specificity 0.88 (95% CI: 0.84–0.91). The results showed that without heart rate control, the sensitivity and specificity at the patient level did not decrease (p = 0.27 and 0.56, respectively). At the artery level, no significant differences in sensitivity and specificity for studies with and without heart rate control were detected (p = 0.04 and 0.05, respectively). At the segment level, the specificity decreased without heart rate control (p = 0.03), whereas the sensitivity was not influenced (p = 0.63). The median radiation exposure was 2.6 mSv, with 1.6 mSv and 8 mSv for heart rate-controlled studies and uncontrolled studies, respectively. Conclusions: DSCT coronary angiography without heart rate control has a similar excellent diagnostic performance at the patient level as that of heart rate control groups. However, controlling for heart rate to decrease radiation and to provide effective information for selecting the therapeutic strategy and risk stratification is recommended

  19. Prospectively ECG-triggered sequential dual-source coronary CT angiography in patients with atrial fibrillation: comparison with retrospectively ECG-gated helical CT

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Lei; Yang, Lin; Zhang, Zhaoqi [Capital Medical University, Department of Radiology, Beijing Anzhen Hospital, Beijing (China); Wang, Yining; Jin, Zhengyu [Chinese Academy of Medical Sciences, Department of Radiology, Peking Union Medical College Hospital, Beijing (China); Zhang, Longjiang; Lu, Guangming [Nanjing University, Department of Medical Imaging, Jinling Hospital, Clinical School of Medical College, Nanjing, Jiangsu (China)

    2013-07-15

    To investigate the feasibility of applying prospectively ECG-triggered sequential coronary CT angiography (CCTA) to patients with atrial fibrillation (AF) and evaluate the image quality and radiation dose compared with a retrospectively ECG-gated helical protocol. 100 patients with persistent AF were enrolled. Fifty patients were randomly assigned to a prospective protocol and the other patients to a retrospective protocol using a second-generation dual-source CT (DS-CT). Image quality was evaluated using a four-point grading scale (1 = excellent, 2 = good, 3 = moderate, 4 = poor) by two reviewers on a per-segment basis. The coronary artery segments were considered non-diagnostic with a quality score of 4. The radiation dose was evaluated. Diagnostic segment rate in the prospective group was 99.4 % (642/646 segments), while that in the retrospective group was 96.5 % (604/626 segments) (P < 0.001). Effective dose was 4.29 {+-} 1.86 and 11.95 {+-} 5.34 mSv for each of the two protocols (P < 0.001), which was a 64 % reduction in the radiation dose for prospective sequential imaging compared with retrospective helical imaging. In AF patients, prospectively ECG-triggered sequential CCTA is feasible using second-generation DS-CT and can decrease >60 % radiation exposure compared with retrospectively ECG-gated helical imaging while improving diagnostic image quality. (orig.)

  20. A high performance Ge/Si0.5Ge0.5/Si heterojunction dual sources tunneling transistor with a U-shaped channel

    Science.gov (United States)

    Li, Wei; Liu, Hongxia; Wang, Shulong; Wang, Qianqiong; Chen, Shupeng

    2017-06-01

    In this paper, a new Ge/Si0.5Ge0.5/Si heterojunction dual sources tunneling transistor with a U-shaped channel (Ge_DUTFET) is proposed and investigated by Silvaco-Atlas simulation. The line tunneling perpendicular to channel and point tunneling parallel to channel simultaneously occur on both sides of the gate. The Ge is chosen as the source region material to increase the line tunneling current. The designed heterojunction between the Ge source and Si channel decreases the point tunneling barrier width to enhance the point tunneling current. And this heterojunction can also promote the Ge_DUTFET to occur point tunneling at the small gate voltage, which makes it obtain the smaller turn-on voltage. Furthermore, the Si0.5Ge0.5 buffer layer is also helpful for the enhancement of performance. The simulation results reveal that Ge_DUTFET has the better performance compared with the Si_DUTFET. The on-state current and average subthreshold swing of Ge_DUTFET are 1.11 × 10-5A/μm and 35.1mV/dec respectively. The max cut-off frequency (fT) and gain bandwidth product (GBW) are 26.6 GHz and 16.6 GHz respectively. The fT and GBW of the Ge_DUTFET are respectively increased by ∼27.4% and ∼84.3% compared with the Si_DUTFET.

  1. Usefulness of electrocardiography-gated dual-source computed tomography for evaluating morphological features of the ventricles in children with complex congenital heart defects

    International Nuclear Information System (INIS)

    Nakagawa, Motoo; Hara, Masaki; Sakurai, Keita; Asano, Miki; Shibamoto, Yuta; Ohashi, Kazuya

    2011-01-01

    Improved time resolution using dual-source computed tomography (DSCT) enabled adaptation of electrocardiography (ECG)-gated cardiac CT for children with a high heart rate. In this study, we evaluated the ability of ECG-gated DSCT (ECG-DSCT) to depict the morphological ventricular features in patients with congenital heart disease (CHD). Between August 2006 and March 2010, a total of 66 patients with CHD (aged 1 day to 9 years, median 11 months) were analyzed using ECG-DSCT. The type of anomaly was ventricular septal defect (VSD) in 32 (malaligned type in 20, perimembranous type in 7, supracristal type in 3, muscular type in 2), single ventricle (SV) in 11, and corrected transposition of the great arteries (cTGA) in 3. All patients underwent ECG-DSCT and ultrasonography (US). We evaluated the accuracy of diagnosing the type of VSD. For the cases with SV and cTGA, we evaluated the ability to depict anatomical ventricular features. In all 32 cases of VSD, DSCT could confirm the VSD defects, and the findings were identical to those obtained by US. Anatomical configurations of the SV and cTGA were correctly diagnosed, similar to that on US. Our study suggests that ECG-DSCT can clearly depict the configuration of ventricles. (author)

  2. Accuracy of Combined Computed Tomography Colonography and Dual Energy Iiodine Map Imaging for Detecting Colorectal masses using High-pitch Dual-source CT.

    Science.gov (United States)

    Sun, Kai; Han, Ruijuan; Han, Yang; Shi, Xuesen; Hu, Jiang; Lu, Bin

    2018-02-28

    To evaluate the diagnostic accuracy of combined computed tomography colonography (CTC) and dual-energy iodine map imaging for detecting colorectal masses using high-pitch dual-source CT, compared with optical colonography (OC) and histopathologic findings. Twenty-eight consecutive patients were prospectively enrolled in this study. All patients were underwent contrast-enhanced CTC acquisition using dual-energy mode and OC and pathologic examination. The size of the space-occupied mass, the CT value after contrast enhancement, and the iodine value were measured and statistically compared. The sensitivity, specificity, accuracy rate, and positive predictive and negative predictive values of dual-energy contrast-enhanced CTC were calculated and compared between conventional CTC and dual-energy iodine images. The iodine value of stool was significantly lower than the colonic neoplasia (P dual-energy iodine maps imaging was 95.6% (95% CI = 77.9%-99.2%). The specificity of the two methods was 42.8% (95% CI = 15.4%-93.5%) and 100% (95% CI = 47.9%-100%; P = 0.02), respectively. Compared with optical colonography and histopathology, combined CTC and dual-energy iodine maps imaging can distinguish stool and colonic neoplasia, distinguish between benign and malignant tumors initially and improve the diagnostic accuracy of CTC for colorectal cancer screening.

  3. Initial results of a new generation dual source CT system using only an in-plane comb filter for ultra-high resolution temporal bone imaging

    International Nuclear Information System (INIS)

    Meyer, Mathias; Haubenreisser, Holger; Schoenberg, Stefan O.; Henzler, Thomas; Raupach, Rainer; Schmidt, Bernhard; Leidecker, Christianne; Allmendinger, Thomas; Flohr, Thomas; Lietzmann, Florian; Schad, Lothar R.

    2015-01-01

    To prospectively evaluate radiation dose and image quality of a third generation dual-source CT (DSCT) without z-axis filter behind the patient for temporal bone CT. Forty-five patients were either examined on a first, second, or third generation DSCT in an ultra-high-resolution (UHR) temporal bone-imaging mode. On the third generation DSCT system, the tighter focal spot of 0.2 mm 2 removesthe necessity for an additional z-axis-filter, leading to an improved z-axis radiation dose efficiency. Images of 0.4 mm were reconstructed using standard filtered-back-projection or iterative reconstruction (IR) technique for previous generations of DSCT and a novel IR algorithm for the third generation DSCT. Radiation dose and image quality were compared between the three DSCT systems. The statistically significantly highest subjective and objective image quality was evaluated for the third generation DSCT when compared to the first or second generation DSCT systems (all p < 0.05). Total effective dose was 63 %/39 % lower for the third generation examination as compared to the first and second generation DSCT. Temporal bone imaging without z-axis-UHR-filter and a novel third generation IR algorithm allows for significantly higher image quality while lowering effective dose when compared to the first two generations of DSCTs. (orig.)

  4. Radiation dose considerations by intra-individual Monte Carlo simulations in dual source spiral coronary computed tomography angiography with electrocardiogram-triggered tube current modulation and adaptive pitch

    Energy Technology Data Exchange (ETDEWEB)

    May, Matthias S.; Kuettner, Axel; Lell, Michael M.; Wuest, Wolfgang; Scharf, Michael; Uder, Michael [University of Erlangen, Department of Radiology, Erlangen (Germany); Deak, Paul; Kalender, Willi A. [University of Erlangen, Department of Medical Physics, Erlangen (Germany); Keller, Andrea K.; Haeberle, Lothar [University of Erlangen, Department of Medical Informatics, Biometry and Epidemiology, Erlangen (Germany); Achenbach, Stephan; Seltmann, Martin [University of Erlangen, Department of Cardiology, Erlangen (Germany)

    2012-03-15

    To evaluate radiation dose levels in patients undergoing spiral coronary computed tomography angiography (CTA) on a dual-source system in clinical routine. Coronary CTA was performed for 56 patients with electrocardiogram-triggered tube current modulation (TCM) and heart-rate (HR) dependent pitch adaptation. Individual Monte Carlo (MC) simulations were performed for dose assessment. Retrospective simulations with constant tube current (CTC) served as reference. Lung tissue was segmented and used for organ and effective dose (ED) calculation. Estimates for mean relative ED was 7.1 {+-} 2.1 mSv/100 mAs for TCM and 12.5 {+-} 5.3 mSv/100 mAs for CTC (P < 0.001). Relative dose reduction at low HR ({<=}60 bpm) was highest (49 {+-} 5%) compared to intermediate (60-70 bpm, 33 {+-} 12%) and high HR (>70 bpm, 29 {+-} 12%). However lowest ED is achieved at high HR (5.2 {+-} 1.5 mSv/100 mAs), compared with intermediate (6.7 {+-} 1.6 mSv/100 mAs) and low (8.3 {+-} 2.1 mSv/100 mAs) HR when automated pitch adaptation is applied. Radiation dose savings up to 52% are achievable by TCM at low and regular HR. However lowest ED is attained at high HR by pitch adaptation despite inferior radiation dose reduction by TCM. circle Monte Carlo simulations allow for individual radiation dose calculations. (orig.)

  5. Radiation dose considerations by intra-individual Monte Carlo simulations in dual source spiral coronary computed tomography angiography with electrocardiogram-triggered tube current modulation and adaptive pitch

    International Nuclear Information System (INIS)

    May, Matthias S.; Kuettner, Axel; Lell, Michael M.; Wuest, Wolfgang; Scharf, Michael; Uder, Michael; Deak, Paul; Kalender, Willi A.; Keller, Andrea K.; Haeberle, Lothar; Achenbach, Stephan; Seltmann, Martin

    2012-01-01

    To evaluate radiation dose levels in patients undergoing spiral coronary computed tomography angiography (CTA) on a dual-source system in clinical routine. Coronary CTA was performed for 56 patients with electrocardiogram-triggered tube current modulation (TCM) and heart-rate (HR) dependent pitch adaptation. Individual Monte Carlo (MC) simulations were performed for dose assessment. Retrospective simulations with constant tube current (CTC) served as reference. Lung tissue was segmented and used for organ and effective dose (ED) calculation. Estimates for mean relative ED was 7.1 ± 2.1 mSv/100 mAs for TCM and 12.5 ± 5.3 mSv/100 mAs for CTC (P 70 bpm, 29 ± 12%). However lowest ED is achieved at high HR (5.2 ± 1.5 mSv/100 mAs), compared with intermediate (6.7 ± 1.6 mSv/100 mAs) and low (8.3 ± 2.1 mSv/100 mAs) HR when automated pitch adaptation is applied. Radiation dose savings up to 52% are achievable by TCM at low and regular HR. However lowest ED is attained at high HR by pitch adaptation despite inferior radiation dose reduction by TCM. circle Monte Carlo simulations allow for individual radiation dose calculations. (orig.)

  6. The value of low-dose prospective ECG-gated dual-source CT angiography in the diagnosis of coarctation of the aorta in infants and children

    Energy Technology Data Exchange (ETDEWEB)

    Nie, P. [Shandong Provincial Key Laboratory of Diagnosis and Treatment of Cardio-Cerebral Vascular Diseases, Shandong Medical Imaging Research Institute, Shandong University, Jinan, Shandong (China); Wang, X., E-mail: wxming369@yahoo.com.cn [Shandong Provincial Key Laboratory of Diagnosis and Treatment of Cardio-Cerebral Vascular Diseases, Shandong Medical Imaging Research Institute, Shandong University, Jinan, Shandong (China); Cheng, Z.; Duan, Y.; Ji, X. [Shandong Provincial Key Laboratory of Diagnosis and Treatment of Cardio-Cerebral Vascular Diseases, Shandong Medical Imaging Research Institute, Shandong University, Jinan, Shandong (China); Chen, J. [CT Research Collaboration, Siemens, Beijing (China); Zhang, H. [Department of Cardiovascular Surgery, Shandong Provincial Hospital, Jinan, Shandong (China)

    2012-08-15

    Aim: To investigate the value of prospective electrocardiogram (ECG)-gated dual-source computed tomography (DSCT) in the diagnosis of coarctation of the aorta (CoA). Materials and methods: Seventeen patients clinically suspected of having CoA underwent prospective ECG-gated DSCT angiography and transthoracic echocardiography (TTE). Surgery was performed in all patients. The diagnostic accuracy of DSCT angiography and TTE was compared with the surgical findings as the reference standard. Image quality was evaluated using a five-point scale. Effective radiation dose was calculated from the dose-length product (DLP). Results: CoA was diagnosed in 17 patients by DSCT angiography and in 16 patients by TTE. A total of 46 separate cardiovascular abnormalities were confirmed by surgical findings. The diagnostic accuracy of DSCT angiography and TTE was 96.32% and 97.06%, respectively. There was no significant difference in the diagnostic accuracy between DSCT angiography and TTE ({chi}{sup 2} = 0, p > 0.05). The mean score of image quality was 4.2 {+-} 0.8. The mean effective dose was 0.69 {+-} 0.09 mSv. Conclusion: Prospective ECG-gated DSCT with a low radiation dose is a valuable technique in the diagnosis of CoA in infants and children.

  7. Separation of hepatic iron and fat by dual-source dual-energy computed tomography based on material decomposition: an animal study.

    Science.gov (United States)

    Ma, Jing; Song, Zhi-Qiang; Yan, Fu-Hua

    2014-01-01

    To explore the feasibility of dual-source dual-energy computed tomography (DSDECT) for hepatic iron and fat separation in vivo. All of the procedures in this study were approved by the Research Animal Resource Center of Shanghai Ruijin Hospital. Sixty rats that underwent DECT scanning were divided into the normal group, fatty liver group, liver iron group, and coexisting liver iron and fat group, according to Prussian blue and HE staining. The data for each group were reconstructed and post-processed by an iron-specific, three-material decomposition algorithm. The iron enhancement value and the virtual non-iron contrast value, which indicated overloaded liver iron and residual liver tissue, respectively, were measured. Spearman's correlation and one-way analysis of variance (ANOVA) were performed, respectively, to analyze statistically the correlations with the histopathological results and differences among groups. The iron enhancement values were positively correlated with the iron pathology grading (r = 0.729, pVNC) values were negatively correlated with the fat pathology grading (r = -0.642,pVNC values (F = 25.308,pVNC values were only observed between the fat-present and fat-absent groups. Separation of hepatic iron and fat by dual energy material decomposition in vivo was feasible, even when they coexisted.

  8. Evaluation of an exposed-radiation dose on a dual-source cardiac computed tomography examination with a prospective electrocardiogram-gated fast dual spiral scan

    International Nuclear Information System (INIS)

    Matsubara, Kosuke; Koshida, Kichiro; Koshida, Haruka; Sakuta, Keita; Hayashi, Hiroyuki; Takata, Tadanori; Horii, Junsei; Kawai, Keiichi; Yamamoto, Tomoyuki

    2012-01-01

    We evaluated exposed-radiation doses on dual-source cardiac computed tomography (CT) examinations with prospective electrocardiogram (ECG)-gated fast dual spiral scans. After placing dosimeters at locations corresponding to each of the thoracic organs, prospective ECG-gated fast dual spirals and retrospective ECG-gated dual spiral scans were performed to measure the absorbed dose of each organ. In the prospective ECG-gated fast dual spiral scans, the average absorbed doses were 5.03 mGy for the breast, 9.96 mGy for the heart, 6.60 mGy for the lung, 6.48 mGy for the bone marrow, 9.73 mGy for the thymus, and 4.58 mGy for the skin. These values were about 5% of the absorbed doses for the retrospective ECG-gated dual spiral scan. However, the absorbed dose differed greatly at each scan, especially in the external organs such as the breast. For effective and safe use of the prospective ECG-gated fast dual spiral scan, it is necessary to understand these characteristics sufficiently. (author)

  9. Prevalence of first-pass myocardial perfusion defects detected by contrast-enhanced dual-source CT in patients with non-ST segment elevation acute coronary syndromes

    Energy Technology Data Exchange (ETDEWEB)

    Schepis, Tiziano; Achenbach, Stephan; Marwan, Mohamed; Muschiol, Gerd; Ropers, Dieter; Daniel, Werner G.; Pflederer, Tobias [University of Erlangen, Department of Internal Medicine 2 (Cardiology), Erlangen (Germany)

    2010-07-15

    To investigate the prevalence and diagnostic value of first-pass myocardial perfusion defects (PD) visualised by contrast-enhanced multidetector computed tomography (MDCT) in patients admitted for a first acute coronary syndrome (ACS). Thirty-eight patients with non-ST segment elevation myocardial infarction (NSTEMI) or unstable angina (UA) and scheduled for percutaneous coronary intervention underwent dual-source CT immediately before catheterisation. CT images were analysed for the presence of any PD by using a 17-segment model. Results were compared with peak cardiac troponin-I (cTnI) and angiography findings. PD were seen in 21 of the 24 patients with NSTEMI (median peak cTnI level 7.07 ng/mL; range 0.72-37.07 ng/mL) and in 2 of 14 patients with UA. PD corresponded with the territory of the infarct-related artery in 20 out of 22 patients. In a patient-based analysis, sensitivity, specificity, negative and positive predictive values of any PD for predicting NSTEMI were 88%, 86%, 80% and 91%. Per culprit artery, the respective values were 86%, 75%, 80% and 83%. In patients with non-ST segment elevation ACS, first-pass myocardial PD in contrast-enhanced MDCT correlate closely with the presence of myocardial necrosis, as determined by increases in cTnI levels. (orig.)

  10. Effect of the high-pitch mode in dual-source computed tomography on the accuracy of three-dimensional volumetry of solid pulmonary nodules: A phantom study

    International Nuclear Information System (INIS)

    Hwang, Sung Ho; Oh, Yu Whan; Ham, Soo Youn; Kang, Eun Young; Lee, Ki Yeol

    2015-01-01

    To evaluate the influence of high-pitch mode (HPM) in dual-source computed tomography (DSCT) on the accuracy of three-dimensional (3D) volumetry for solid pulmonary nodules. A lung phantom implanted with 45 solid pulmonary nodules (n = 15 for each of 4-mm, 6-mm, and 8-mm in diameter) was scanned twice, first in conventional pitch mode (CPM) and then in HPM using DSCT. The relative percentage volume errors (RPEs) of 3D volumetry were compared between the HPM and CPM. In addition, the intermode volume variability (IVV) of 3D volumetry was calculated. In the measurement of the 6-mm and 8-mm nodules, there was no significant difference in RPE (p > 0.05, respectively) between the CPM and HPM (IVVs of 1.2 +/- 0.9%, and 1.7 +/- 1.5%, respectively). In the measurement of the 4-mm nodules, the mean RPE in the HPM (35.1 +/- 7.4%) was significantly greater (p < 0.01) than that in the CPM (18.4 +/- 5.3%), with an IVV of 13.1 +/- 6.6%. However, the IVVs were in an acceptable range (< 25%), regardless of nodule size. The accuracy of 3D volumetry with HPM for solid pulmonary nodule is comparable to that with CPM. However, the use of HPM may adversely affect the accuracy of 3D volumetry for smaller (< 5 mm in diameter) nodule.

  11. Effect of the high-pitch mode in dual-source computed tomography on the accuracy of three-dimensional volumetry of solid pulmonary nodules: A phantom study

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Sung Ho; Oh, Yu Whan; Ham, Soo Youn [Dept. of Radiology, Korea University Anam Hospital, Seoul (Korea, Republic of); Kang, Eun Young [Dept. of Radiology, Korea University Guro Hospital, Seoul (Korea, Republic of); Lee, Ki Yeol [Dept. of Radiology, Korea University Ansan Hospital, Ansan (Korea, Republic of)

    2015-06-15

    To evaluate the influence of high-pitch mode (HPM) in dual-source computed tomography (DSCT) on the accuracy of three-dimensional (3D) volumetry for solid pulmonary nodules. A lung phantom implanted with 45 solid pulmonary nodules (n = 15 for each of 4-mm, 6-mm, and 8-mm in diameter) was scanned twice, first in conventional pitch mode (CPM) and then in HPM using DSCT. The relative percentage volume errors (RPEs) of 3D volumetry were compared between the HPM and CPM. In addition, the intermode volume variability (IVV) of 3D volumetry was calculated. In the measurement of the 6-mm and 8-mm nodules, there was no significant difference in RPE (p > 0.05, respectively) between the CPM and HPM (IVVs of 1.2 +/- 0.9%, and 1.7 +/- 1.5%, respectively). In the measurement of the 4-mm nodules, the mean RPE in the HPM (35.1 +/- 7.4%) was significantly greater (p < 0.01) than that in the CPM (18.4 +/- 5.3%), with an IVV of 13.1 +/- 6.6%. However, the IVVs were in an acceptable range (< 25%), regardless of nodule size. The accuracy of 3D volumetry with HPM for solid pulmonary nodule is comparable to that with CPM. However, the use of HPM may adversely affect the accuracy of 3D volumetry for smaller (< 5 mm in diameter) nodule.

  12. Effect of the high-pitch mode in dual-source computed tomography on the accuracy of three-dimensional volumetry of solid pulmonary nodules: a phantom study.

    Science.gov (United States)

    Hwang, Sung Ho; Oh, Yu-Whan; Ham, Soo-Youn; Kang, Eun-Young; Lee, Ki Yeol

    2015-01-01

    To evaluate the influence of high-pitch mode (HPM) in dual-source computed tomography (DSCT) on the accuracy of three-dimensional (3D) volumetry for solid pulmonary nodules. A lung phantom implanted with 45 solid pulmonary nodules (n = 15 for each of 4-mm, 6-mm, and 8-mm in diameter) was scanned twice, first in conventional pitch mode (CPM) and then in HPM using DSCT. The relative percentage volume errors (RPEs) of 3D volumetry were compared between the HPM and CPM. In addition, the intermode volume variability (IVV) of 3D volumetry was calculated. In the measurement of the 6-mm and 8-mm nodules, there was no significant difference in RPE (p > 0.05, respectively) between the CPM and HPM (IVVs of 1.2 ± 0.9%, and 1.7 ± 1.5%, respectively). In the measurement of the 4-mm nodules, the mean RPE in the HPM (35.1 ± 7.4%) was significantly greater (p volumetry with HPM for solid pulmonary nodule is comparable to that with CPM. However, the use of HPM may adversely affect the accuracy of 3D volumetry for smaller (< 5 mm in diameter) nodule.

  13. 3T MRI and 128-slice dual-source CT cisternography images of the cranial nerves a brief pictorial review for clinicians.

    Science.gov (United States)

    Roldan-Valadez, Ernesto; Martinez-Anda, Jaime J; Corona-Cedillo, Roberto

    2014-01-01

    There is a broad community of health sciences professionals interested in the anatomy of the cranial nerves (CNs): specialists in neurology, neurosurgery, radiology, otolaryngology, ophthalmology, maxillofacial surgery, radiation oncology, and emergency medicine, as well as other related fields. Advances in neuroimaging using high-resolution images from computed tomography (CT) and magnetic resonance (MR) have made highly-detailed visualization of brain structures possible, allowing normal findings to be routinely assessed and nervous system pathology to be detected. In this article we present an integrated perspective of the normal anatomy of the CNs established by radiologists and neurosurgeons in order to provide a practical imaging review, which combines 128-slice dual-source multiplanar images from CT cisternography and 3T MR curved reconstructed images. The information about the CNs includes their origin, course (with emphasis on the cisternal segments and location of the orifices at the skull base transmitting them), function, and a brief listing of the most common pathologies affecting them. The scope of the article is clinical anatomy; readers will find specialized texts presenting detailed information about particular topics. Our aim in this article is to provide a helpful reference for understanding the complex anatomy of the cranial nerves. Copyright © 2013 Wiley Periodicals, Inc.

  14. Evaluation of dual-source parallel RF excitation for diffusion-weighted whole-body MR imaging with background body signal suppression at 3.0 T.

    Science.gov (United States)

    Mürtz, Petra; Kaschner, Marius; Träber, Frank; Kukuk, Guido M; Büdenbender, Sarah M; Skowasch, Dirk; Gieseke, Jürgen; Schild, Hans H; Willinek, Winfried A

    2012-11-01

    To evaluate the use of dual-source parallel RF excitation (TX) for diffusion-weighted whole-body MRI with background body signal suppression (DWIBS) at 3.0 T. Forty consecutive patients were examined on a clinical 3.0-T MRI system using a diffusion-weighted (DW) spin-echo echo-planar imaging sequence with a combination of short TI inversion recovery and slice-selective gradient reversal fat suppression. DWIBS of the neck (n=5), thorax (n=8), abdomen (n=6) and pelvis (n=21) was performed both with TX (2:56 min) and with standard single-source RF excitation (4:37 min). The quality of DW images and reconstructed inverted maximum intensity projections was visually judged by two readers (blinded to acquisition technique). Signal homogeneity and fat suppression were scored as "improved", "equal", "worse" or "ambiguous". Moreover, the apparent diffusion coefficient (ADC) values were measured in muscles, urinary bladder, lymph nodes and lesions. By the use of TX, signal homogeneity was "improved" in 25/40 and "equal" in 15/40 cases. Fat suppression was "improved" in 17/40 and "equal" in 23/40 cases. These improvements were statistically significant (p3.0 T with respect to signal homogeneity and fat suppression, reduced scan time by approximately one-third, and did not influence the measured ADC values. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  15. Follow-up of coronary artery bypass graft patency: diagnostic efficiency of high-pitch dual-source 256-slice MDCT findings.

    Science.gov (United States)

    Yuceler, Zeyneb; Kantarci, Mecit; Yuce, Ihsan; Kizrak, Yesim; Bayraktutan, Ummugulsum; Ogul, Hayri; Kiris, Adem; Celik, Omer; Pirimoglu, Berhan; Genc, Berhan; Gundogdu, Fuat

    2014-01-01

    Our aim was to evaluate the diagnostic accuracy of 256-slice, high-pitch mode multidetector computed tomography (MDCT) for coronary artery bypass graft (CABG) patency. Eighty-eight patients underwent 256-slice MDCT angiography to evaluate their graft patency after CABG surgery using a prospectively synchronized electrocardiogram in the high-pitch spiral acquisition mode. Effective radiation doses were calculated. We investigated the diagnostic accuracy of high-pitch, low-dose, prospective, electrocardiogram-triggering, dual-source MDCT for CABG patency compared with catheter coronary angiography imaging findings. A total of 215 grafts and 645 vessel segments were analyzed. All graft segments had diagnostic image quality. The proximal and middle graft segments had significantly (P < 0.05) better mean image quality scores (1.18 ± 0.4) than the distal segments (1.31 ± 0.5). Using catheter coronary angiography as the reference standard, high-pitch MDCT had the following sensitivity, specificity, positive predictive value, and negative predictive value of per-segment analysis for detecting graft patency: 97.1%, 99.6%, 94.4%, and 99.8%, respectively. In conclusion, MDCT can be used noninvasively with a lower radiation dose for the assessment of restenosis in CABG patients.

  16. Computer simulation of lower-hybrid heating and current drive in tokamaks. Progress report, September 1, 1982-July 1, 1983

    International Nuclear Information System (INIS)

    Ogden, J.M.

    1983-07-01

    A lower hybrid ray tracing package has been adapted for use in the PPPL 1-D tokamak transport code TRANSP. The code LHRAY has been written in OLYMPUS format and is suitable for use as a separate simulation program or in conjunction with TRANSP. The generality of the OLYMPUS conventions was chosen in order to make LHRAY easily transferable to other OLYMPUS style transport codes such as BALDUR. The details of LHRAY are described in this report. The physical model documented in our first progress report has been used with one major modification. Instead of solving the 1-D Fokker-Planck equations numerically to give the electron distribution function F/sub e/ in the presence of a background electric field, we have approximated F/sub e/ analytically using the theory of Liu et al for runaway electron distributions. The organization of LHRAY is given and the naming conventions are noted. Finally, preliminary results are presented. Program documentation and a listing of the code are included as appendices

  17. Analysis of combined conduction and radiation heat transfer in presence of participating medium by the development of hybrid method

    International Nuclear Information System (INIS)

    Mahapatra, S.K.; Dandapat, B.K.; Sarkar, A.

    2006-01-01

    The current study addresses the mathematical modeling aspects of coupled conductive and radiative heat transfer in the presence of absorbing, emitting and isotropic scattering gray medium within two-dimensional square enclosure. A blended method where the concepts of modified differential approximation employed by combining discrete ordinate method and spherical harmonics method, has been developed for modeling the radiative transport equation. The gray participating medium is bounded by isothermal walls of two-dimensional enclosure which are considered to be opaque, diffuse and gray. The effect of various influencing parameters i.e., radiation-conduction parameter, surface emissivity, single scattering albedo and optical thickness has been illustrated. The adaptability of the present method has also been addressed

  18. Poloidal inhomogeneity of the particle fluctuation induced fluxes near of the LCFS at lower hybrid heating and improved confinement transition at the FT-2 tokamak

    International Nuclear Information System (INIS)

    Lashkul, S.I.; Altukhov, A.B.; Gurchenko, A.D.; Gusakov, E.Z.; Dyachenko, V.V.; Esipov, L.A.; Kantor, M.Y.; Kouprienko, D.V.; Stepanov, A.Y.; Sharpeonok, A.P.; Shatalin, S.V.; Vekshina, E.O.

    2004-01-01

    This paper present our observations and conclusions about development of the transport process at the plasma periphery of the small tokamak FT-2 during additional Lower Hybrid Heating (LHH), when external (ETB) transport barrier followed by Internal (ITB) transport barrier is observed. The peculiarities of the variations of the fluctuation fluxes near periphery are measured by three moveable multi-electrode Langmuir probes (L-probe) located in the same poloidal cross-section of the chamber. So the observed L-H transition and ETB formation after LHH and the associated negative E r rise result mainly from the decrease of the electron temperature (T e ) near inner region of the LCFS (last close flux surface) by greater extent than in SOL (scrape-off layer). This effect is stimulated by decrease of the input power and decrease of the radial correlation coefficient (for r equals 74-77 mm) (and radial particle fluctuation-induced Γ(t)) resulted from ITB formation mechanism during LHH. T e variation in the SOL after LH heating pulse takes place to a lesser extent. Observed non-monotonic radial profile of T e near LCFS with positive δT e /δr rise is kept constant obviously by large longitudinal conductivity and poloidal fluxes from the hotter limiter shadow regions because of the poloidal inhomogeneity of the T e (SOL) and n e (SOL). Such induced negative E r after RF pulse gives fast rise to a quasi-steady-state Γ 0 (t) drift fluxes with reversed direction structure, like 'zonal flows', which may inhibit transport across the flow. Large rise of grad(n e ) after LHH near LCFS with L-H transition is observed after the end of LH pulse for a long time - about 10-15 ms

  19. Mapping Surface Heat Fluxes by Assimilating SMAP Soil Moisture and GOES Land Surface Temperature Data

    Science.gov (United States)

    Lu, Yang; Steele-Dunne, Susan C.; Farhadi, Leila; van de Giesen, Nick

    2017-12-01

    Surface heat fluxes play a crucial role in the surface energy and water balance. In situ measurements are costly and difficult, and large-scale flux mapping is hindered by surface heterogeneity. Previous studies have demonstrated that surface heat fluxes can be estimated by assimilating land surface temperature (LST) and soil moisture to determine two key parameters: a neutral bulk heat transfer coefficient (CHN) and an evaporative fraction (EF). Here a methodology is proposed to estimate surface heat fluxes by assimilating Soil Moisture Active Passive (SMAP) soil moisture data and Geostationary Operational Environmental Satellite (GOES) LST data into a dual-source (DS) model using a hybrid particle assimilation strategy. SMAP soil moisture data are assimilated using a particle filter (PF), and GOES LST data are assimilated using an adaptive particle batch smoother (APBS) to account for the large gap in the spatial and temporal resolution. The methodology is implemented in an area in the U.S. Southern Great Plains. Assessment against in situ observations suggests that soil moisture and LST estimates are in better agreement with observations after assimilation. The RMSD for 30 min (daytime) flux estimates is reduced by 6.3% (8.7%) and 31.6% (37%) for H and LE on average. Comparison against a LST-only and a soil moisture-only assimilation case suggests that despite the coarse resolution, assimilating SMAP soil moisture data is not only beneficial but also crucial for successful and robust flux estimation, particularly when the uncertainties in the model estimates are large.

  20. Serial changes in anatomy and ventricular function on dual-source cardiac computed tomography after the Norwood procedure for hypoplastic left heart syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Goo, Hyun Woo [University of Ulsan College of Medicine, Asan Medical Center, Department of Radiology and Research Institute of Radiology, Seoul (Korea, Republic of)

    2017-12-15

    Accurate evaluation of anatomy and ventricular function after the Norwood procedure in hypoplastic left heart syndrome is important for treatment planning and prognostication, but echocardiography and cardiac MRI have limitations. To assess serial changes in anatomy and ventricular function on dual-source cardiac CT after the Norwood procedure for hypoplastic left heart syndrome. In 14 consecutive patients with hypoplastic left heart syndrome, end-systolic and end-diastolic phase cardiac dual-source CT was performed before and early (average: 1 month) after the Norwood procedure, and repeated late (median: 4.5 months) after the Norwood procedure in six patients. Ventricular functional parameters and indexed morphological measurements including pulmonary artery size, right ventricular free wall thickness, and ascending aorta size on cardiac CT were compared between different time points. Moreover, morphological features including ventricular septal defect, endocardial fibroelastosis and coronary ventricular communication were evaluated on cardiac CT. Right ventricular function and volumes remained unchanged (indexed end-systolic and end-diastolic volumes: 38.9±14.0 vs. 41.1±21.5 ml/m{sup 2}, P=0.7 and 99.5±30.5 vs. 105.1±33.0 ml/m{sup 2}, P=0.6; ejection fraction: 60.1±7.3 vs. 63.8±7.0%, P=0.1, and indexed stroke volume: 60.7±18.0 vs. 64.0±15.6 ml/m{sup 2}, P=0.5) early after the Norwood procedure, but function was decreased (ejection fraction: 64.2±2.6 vs. 58.1±7.1%, P=0.01) and volume was increased (indexed end-systolic and end-diastolic volumes: 39.2±14.9 vs. 68.9±20.6 ml/m{sup 2}, P<0.003 and 107.8±36.5 vs. 162.9±36.2 ml/m{sup 2}, P<0.006, and indexed stroke volume: 68.6±21.7 vs. 94.0±21.3 ml/m{sup 2}, P=0.02) later. Branch pulmonary artery size showed a gradual decrease without asymmetry after the Norwood procedure. Right and left pulmonary artery stenoses were identified in 21.4% (3/14) of the patients. Indexed right ventricular free wall

  1. Imaging the Parasinus Region with a Third-Generation Dual-Source CT and the Effect of Tin Filtration on Image Quality and Radiation Dose.

    Science.gov (United States)

    Lell, M M; May, M S; Brand, M; Eller, A; Buder, T; Hofmann, E; Uder, M; Wuest, W

    2015-07-01

    CT is the imaging technique of choice in the evaluation of midface trauma or inflammatory disease. We performed a systematic evaluation of scan protocols to optimize image quality and radiation exposure on third-generation dual-source CT. CT protocols with different tube voltage (70-150 kV), current (25-300 reference mAs), prefiltration, pitch value, and rotation time were systematically evaluated. All images were reconstructed with iterative reconstruction (Advanced Modeled Iterative Reconstruction, level 2). To individually compare results with otherwise identical factors, we obtained all scans on a frozen human head. Conebeam CT was performed for image quality and dose comparison with multidetector row CT. Delineation of important anatomic structures and incidental pathologic conditions in the cadaver head was evaluated. One hundred kilovolts with tin prefiltration demonstrated the best compromise between dose and image quality. The most dose-effective combination for trauma imaging was Sn100 kV/250 mAs (volume CT dose index, 2.02 mGy), and for preoperative sinus surgery planning, Sn100 kV/150 mAs (volume CT dose index, 1.22 mGy). "Sn" indicates an additional prefiltration of the x-ray beam with a tin filter to constrict the energy spectrum. Exclusion of sinonasal disease was possible with even a lower dose by using Sn100 kV/25 mAs (volume CT dose index, 0.2 mGy). High image quality at very low dose levels can be achieved by using a Sn100-kV protocol with iterative reconstruction. The effective dose is comparable with that of conventional radiography, and the high image quality at even lower radiation exposure favors multidetector row CT over conebeam CT. © 2015 by American Journal of Neuroradiology.

  2. Computed Tomography of the Head and Neck Region for Tumor Staging-Comparison of Dual-Source, Dual-Energy and Low-Kilovolt, Single-Energy Acquisitions.

    Science.gov (United States)

    May, Matthias Stefan; Bruegel, Joscha; Brand, Michael; Wiesmueller, Marco; Krauss, Bernhard; Allmendinger, Thomas; Uder, Michael; Wuest, Wolfgang

    2017-09-01

    The aim of this study was to intra-individually compare the image quality obtained by dual-source, dual-energy (DSDE) computed tomography (CT) examinations and different virtual monoenergetic reconstructions to a low single-energy (SE) scan. Third-generation DSDE-CT was performed in 49 patients with histologically proven malignant disease of the head and neck region. Weighted average images (WAIs) and virtual monoenergetic images (VMIs) for low (40 and 60 keV) and high (120 and 190 keV) energies were reconstructed. A second scan aligned to the jaw, covering the oral cavity, was performed for every patient to reduce artifacts caused by dental hardware using a SE-CT protocol with 70-kV tube voltages and matching radiation dose settings. Objective image quality was evaluated by calculating contrast-to-noise ratios. Subjective image quality was evaluated by experienced radiologists. Highest contrast-to-noise ratios for vessel and tumor attenuation were obtained in 40-keV VMI (all P image quality was also highest for 40-keV, but differences to 60-keV VMI, WAI, and 70-kV SE were nonsignificant (all P > 0.05). High kiloelectron volt VMIs reduce metal artifacts with only limited diagnostic impact because of insufficiency in case of severe dental hardware. CTDIvol did not differ significantly between both examination protocols (DSDE: 18.6 mGy; 70-kV SE: 19.4 mGy; P = 0.10). High overall image quality for tumor delineation in head and neck imaging were obtained with 40-keV VMI. However, 70-kV SE examinations are an alternative and modified projections aligned to the jaw are recommended in case of severe artifacts caused by dental hardware.

  3. Dose reduction in abdominal computed tomography: intraindividual comparison of image quality of full-dose standard and half-dose iterative reconstructions with dual-source computed tomography.

    Science.gov (United States)

    May, Matthias S; Wüst, Wolfgang; Brand, Michael; Stahl, Christian; Allmendinger, Thomas; Schmidt, Bernhard; Uder, Michael; Lell, Michael M

    2011-07-01

    We sought to evaluate the image quality of iterative reconstruction in image space (IRIS) in half-dose (HD) datasets compared with full-dose (FD) and HD filtered back projection (FBP) reconstruction in abdominal computed tomography (CT). To acquire data with FD and HD simultaneously, contrast-enhanced abdominal CT was performed with a dual-source CT system, both tubes operating at 120 kV, 100 ref.mAs, and pitch 0.8. Three different image datasets were reconstructed from the raw data: Standard FD images applying FBP which served as reference, HD images applying FBP and HD images applying IRIS. For the HD data sets, only data from 1 tube detector-system was used. Quantitative image quality analysis was performed by measuring image noise in tissue and air. Qualitative image quality was evaluated according to the European Guidelines on Quality criteria for CT. Additional assessment of artifacts, lesion conspicuity, and edge sharpness was performed. : Image noise in soft tissue was substantially decreased in HD-IRIS (-3.4 HU, -22%) and increased in HD-FBP (+6.2 HU, +39%) images when compared with the reference (mean noise, 15.9 HU). No significant differences between the FD-FBP and HD-IRIS images were found for the visually sharp anatomic reproduction, overall diagnostic acceptability (P = 0.923), lesion conspicuity (P = 0.592), and edge sharpness (P = 0.589), while HD-FBP was rated inferior. Streak artifacts and beam hardening was significantly more prominent in HD-FBP while HD-IRIS images exhibited a slightly different noise pattern. Direct intrapatient comparison of standard FD body protocols and HD-IRIS reconstruction suggest that the latest iterative reconstruction algorithms allow for approximately 50% dose reduction without deterioration of the high image quality necessary for confident diagnosis.

  4. Effect of Heart Rate and Coronary Calcification on the Diagnostic Accuracy of the Dual-Source CT Coronary Angiography in Patients with Suspected Coronary Artery Disease

    International Nuclear Information System (INIS)

    Meng, Lingdong; Cui, Lianqun; Cheng, Yuntao; Wu, Xiaoyan; Tang, Yuansheng; Wang, Yong; Xu, Fayun

    2009-01-01

    To evaluate the diagnostic accuracy of a dual-source computed tomography (DSCT) coronary angiography, with a particular focus on the effect of heart rate and calcifications. One hundred and nine patients with suspected coronary disease were divided into 2 groups according to a mean heart rate ( 400). Next, the effect of heart rate and calcification on the accuracy of coronary artery stenosis detection was analyzed by using an invasive coronary angiography as a reference standard. Coronary segments of less than 1.5 mm in diameter in an American Heart Association (AHA) 15-segment model were independently assessed. The mean heart rate during the scan was 71.8 bpm, whereas the mean Agatston score was 226.5. Of the 1,588 segments examined, 1,533 (97%) were assessable. A total of 17 patients had calcium scores above 400 Agatston U, whereas 50 had heart rates ≥ 70 bpm. Overall the sensitivity, specificity, positive predictive values (PPV) and negative predictive values (NPV) for significant stenoses were: 95%, 91%, 65%, and 99% (by segment), respectively and 97%, 90%, 81%, and 91% (by artery), respectively (n = 475). Heart rate showed no significant impact on lesion detection; however, vessel calcification did show a significant impact on accuracy of assessment for coronary segments. The specificity, PPV and accuracy were 96%, 80%, and 96% (by segment), respectively for an Agatston score less than 100% and 99%, 96% and 98% (by artery). For an Agatston score of greater to or equal to 400 the specificity, PPV and accuracy were reduced to 79%, 55%, and 83% (by segment), respectively and to 79%, 69%, and 85% (by artery), respectively. The DSCT provides a high rate of accuracy for the detection of significant coronary artery disease, even in patients with high heart rates and evidence of coronary calcification. However, patients with severe coronary calcification (> 400 U) remain a challenge to diagnose

  5. Assessment of Double Outlet Right Ventricle Associated with Multiple Malformations in Pediatric Patients Using Retrospective ECG-Gated Dual-Source Computed Tomography.

    Directory of Open Access Journals (Sweden)

    Ke Shi

    Full Text Available To evaluate the feasibility and diagnostic accuracy of retrospective electrocardiographically (ECG-gated dual-source computed tomography (DSCT for the assessment of double outlet right ventricle (DORV and associated multiple malformations in pediatric patients.Forty-seven patients <10 years of age with DORV underwent retrospective ECG-gated DSCT. The location of the ventricular septal defect (VSD, alignment of the two great arteries, and associated malformations were assessed. The feasibility of retrospective ECG-gated DSCT in pediatric patients was assessed, the image quality of DSCT and the agreement of the diagnosis of associated malformations between DSCT and transthoracic echocardiography (TTE were evaluated, the diagnostic accuracies of DSCT and TTE were referred to surgical results, and the effective doses were calculated.Apart from DORV, 109 associated malformations were confirmed postoperatively. There was excellent agreement (κ = 0.90 for the diagnosis of associated malformations between DSCT and TTE. However, DSCT was superior to TTE in demonstrating paracardiac anomalies (sensitivity, coronary artery anomalies: 100% vs. 80.00%, anomalies of great vessels: 100% vs. 88.57%, separate thoracic and abdominal anomalies: 100% vs. 76.92%, respectively. Combined with TTE, DSCT can achieve excellent diagnostic performance in intracardiac anomalies (sensitivity, 91.30% vs. 100%. The mean image quality score was 3.70 ± 0.46 (κ = 0.76. The estimated mean effective dose was < 1 mSv (0.88 ± 0.34 mSv.Retrospective ECG-gated DSCT is a better diagnostic tool than TTE for pediatric patients with complex congenital heart disease such as DORV. Combined with TTE, it may reduce or even obviate the use of invasive cardiac catheterization, and thus expose the patients to a much lower radiation dose.

  6. Diagnostic Accuracy of Dual-Source Computerized Tomography Coronary Angiography in Symptomatic Patients Presenting to a Referral Cardiovascular Center During Daily Clinical Practice

    International Nuclear Information System (INIS)

    Mahdavi, Arash; Mohammadzadeh, Ali; Joodi, Golsa; Tabatabaei, Mohammad Reza; Sheikholeslami, Farhad; Motevalli, Marzieh

    2016-01-01

    There are numerous studies that address the diagnostic value of dual-source computed tomography (DSCT) as an alternative to conventional coronary angiography (CCA). However, the benefit of application of DSCT in a real world clinical setting should be evaluated. To determine the diagnostic accuracy of DSCT technique compared with CCA as the gold standard method in detection of coronary artery stenosis among symptomatic patients who are presented to a referral cardiovascular center during daily clinical practice. Evaluating the medical records of a tertiary care referral cardiovascular center, 47 patients who had undergone DSCT and CCA, and also met the inclusion and exclusion criteria of the study were selected. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and likelihood ratios (LRs) of the DSCT imaging technique were calculated. In total, 97.8% of the segments (628/642) could be visualized with diagnostic image quality via DSCT coronary angiography. The mean heart rate during DSCT was 69.2 ± 12.2 bpm (range: 39 - 83 bpm), and the mean Agatston score was 507.7 ± 590.5 (range: 0 - 2328). Per segment analysis of the findings revealed that the sensitivity, specificity, PPV, NPV, positive LR (PLR) and negative LR (NLR) of DSCT technique for evaluation of patients with coronary artery disease were 93.7%, 96.8%, 92.7%, 97.2%, 29.4, and 0.066, respectively. Also per vessel, analysis of the findings showed a sensitivity of 97.1%, a specificity of 94.0%, PPV of 95.3%, NPV of 96.3%, PLR of 16.1, and NLR of 0.030. Our results indicate that DSCT coronary angiography provides high diagnostic accuracy for the evaluation of CAD patients during daily routine practice of a referral cardiovascular setting

  7. Attenuation-based kV pair selection in dual source dual energy computed tomography angiography of the chest: impact on radiation dose and image quality

    Energy Technology Data Exchange (ETDEWEB)

    Renapurkar, Rahul D.; Azok, Joseph; Lempel, Jason; Karim, Wadih; Graham, Ruffin [Thoracic Imaging, L10, Imaging Institute, Cleveland Clinic, Cleveland, OH (United States); Primak, Andrew [Siemens Medical Solutions, Malvern, PA (United States); Tandon, Yasmeen [Case Western Reserve University-Metro Health Medical Center, Department of Radiology, Cleveland, OH (United States); Bullen, Jennifer [Quantitative Health Sciences, Cleveland Clinic, Cleveland, OH (United States); Dong, Frank [Section of Medical Physics, Cleveland Clinic, Cleveland, OH (United States)

    2017-08-15

    The purpose of this study was to evaluate the impact of attenuation-based kilovoltage (kV) pair selection in dual source dual energy (DSDE)-pulmonary embolism (PE) protocol examinations on radiation dose savings and image quality. A prospective study was carried out on 118 patients with suspected PE. In patients in whom attenuation-based kV pair selection selected the 80/140Sn kV pair, the pre-scan 100/140Sn CTDIvol (computed tomography dose index volume) values were compared with the pre-scan 80/140Sn CTDIvol values. Subjective and objective image quality parameters were assessed. Attenuation-based kV pair selection switched to the 80/140Sn kV pair (''switched'' cohort) in 63 out of 118 patients (53%). The mean 100/140Sn pre-scan CTDIvol was 8.8 mGy, while the mean 80/140Sn pre-scan CTDIvol was 7.5 mGy. The average estimated dose reduction for the ''switched'' cohort was 1.3 mGy (95% CI 1.2, 1.4; p < 0.001), representing a 15% reduction in dose. After adjusting for patient weight, mean attenuation was significantly higher in the ''switched'' vs. ''non-switched'' cohorts in all five pulmonary arteries and in all lobes on iodine maps. This study demonstrates that attenuation-based kV pair selection in DSDE examination is feasible and can offer radiation dose reduction without compromising image quality. (orig.)

  8. Diagnostic Value of 64-Slice Dual-Source CT Coronary Angiography in Patients with Atrial Fibrillation: Comparison with Invasive Coronary Angiography

    International Nuclear Information System (INIS)

    Zhang, Jian Jun; Liu, Tie; Feng, Yue; Wu, Wei Feng; Mou, Cai Yun; Zhai, Li Hao

    2011-01-01

    We wanted to evaluate the image quality and diagnostic value of 64-slice dual-source computed tomography (DSCT) coronary angiography in patients with atrial fibrillation (Afib). The coronary arteries of 22 Afib patients seen on DSCT were classified into 15 segments and the imaging quality (excellent, good, moderate and poor) and significant stenoses (≥ 50%) were evaluated by two radiologists who were blinded to the conventional coronary angiography (CAG) results. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for detecting important coronary artery stenosis were calculated. McNemar test was used to determine any significant difference between DSCT and CAG, and Cohen's Kappa statistics were calculated for the intermodality and interobserver agreement. The mean heart rate was 89 ± 8.3 bpm (range: 80-118 bpm). A range from 250 msec to 300 msec within the RR interval was the optimal reconstruction interval for the patients with Afib. The respective overall sensitivity, specificity, PPV and NPV values were 74%, 97%, 81% and 96% for reader 1 and 72%, 98%, 85% and 96% for reader 2. No significant difference between DSCT and CAG was found for detecting a significant stenosis (reader 1, p = 1.0; reader 2, p = 0.727). Cohen's Kappa statistics demonstrated good intermodality and interobserver agreement. 64-slice DSCT coronary angiography provides good image quality in patients with atrial fibrillation without the need for controlling the heart rate. DSCT can be used for ruling out significant stenosis in patients with atrial fibrillation with its high NPV for detecting in important stenosis.

  9. Diagnostic Value of 64-Slice Dual-Source CT Coronary Angiography in Patients with Atrial Fibrillation: Comparison with Invasive Coronary Angiography

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jian Jun; Liu, Tie; Feng, Yue; Wu, Wei Feng; Mou, Cai Yun; Zhai, Li Hao [Zhejiang Hospital, Hangzhou (China)

    2011-08-15

    We wanted to evaluate the image quality and diagnostic value of 64-slice dual-source computed tomography (DSCT) coronary angiography in patients with atrial fibrillation (Afib). The coronary arteries of 22 Afib patients seen on DSCT were classified into 15 segments and the imaging quality (excellent, good, moderate and poor) and significant stenoses ({>=} 50%) were evaluated by two radiologists who were blinded to the conventional coronary angiography (CAG) results. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for detecting important coronary artery stenosis were calculated. McNemar test was used to determine any significant difference between DSCT and CAG, and Cohen's Kappa statistics were calculated for the intermodality and interobserver agreement. The mean heart rate was 89 {+-} 8.3 bpm (range: 80-118 bpm). A range from 250 msec to 300 msec within the RR interval was the optimal reconstruction interval for the patients with Afib. The respective overall sensitivity, specificity, PPV and NPV values were 74%, 97%, 81% and 96% for reader 1 and 72%, 98%, 85% and 96% for reader 2. No significant difference between DSCT and CAG was found for detecting a significant stenosis (reader 1, p = 1.0; reader 2, p = 0.727). Cohen's Kappa statistics demonstrated good intermodality and interobserver agreement. 64-slice DSCT coronary angiography provides good image quality in patients with atrial fibrillation without the need for controlling the heart rate. DSCT can be used for ruling out significant stenosis in patients with atrial fibrillation with its high NPV for detecting in important stenosis.

  10. Free-breathing high-pitch 80kVp dual-source computed tomography of the pediatric chest: Image quality, presence of motion artifacts and radiation dose.

    Science.gov (United States)

    Bodelle, Boris; Fischbach, Constanze; Booz, Christian; Yel, Ibrahim; Frellesen, Claudia; Beeres, Martin; Vogl, Thomas J; Scholtz, Jan-Erik

    2017-04-01

    To investigate image quality, presence of motion artifacts and effects on radiation dose of 80kVp high-pitch dual-source CT (DSCT) in combination with an advanced modeled iterative reconstruction algorithm (ADMIRE) of the pediatric chest compared to single-source CT (SSCT). The study was approved by the institutional review board. Eighty-seven consecutive pediatric patients (mean age 9.1±4.9years) received either free-breathing high-pitch (pitch 3.2) chest 192-slice DSCT (group 1, n=31) or standard-pitch (pitch 1.2) 128-slice SSCT (group 2, n=56) with breathing-instructions by random assignment. Tube settings were similar in both groups with 80 kVp and 74 ref. mAs. Images were reconstructed using FBP for both groups. Additionally, ADMIRE was used in group 1. Effective thorax diameter, image noise, and signal-to-noise ratio (SNR) of the pectoralis major muscle and the thoracic aorta were calculated. Motion artifacts were measured as doubling boarders of the diaphragm and the heart. Images were rated by two blinded readers for overall image quality and presence of motion artifacts on 5-point-scales. Size specific dose estimates (SSDE, mGy) and effective dose (ED, mSv) were calculated. Age and effective thorax diameter showed no statistically significant differences in both groups. Image noise and SNR were comparable (p>0.64) for SSCT and DSCT with ADMIRE, while DSCT with FBP showed inferior results (pchest DSCT in combination with ADMIRE reduces motion artifacts and increases image quality while lowering radiation exposure in free-breathing pediatric patients without sedation. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Automated tube voltage selection for radiation dose and contrast medium reduction at coronary CT angiography using 3{sup rd} generation dual-source CT

    Energy Technology Data Exchange (ETDEWEB)

    Mangold, Stefanie [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Eberhard-Karls University Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany); Wichmann, Julian L. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt (Germany); Schoepf, U.J. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Medical University of South Carolina, Division of Cardiology, Department of Medicine, Charleston, SC (United States); Poole, Zachary B.; Varga-Szemes, Akos; De Cecco, Carlo N. [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); Canstein, Christian [Siemens Medical Solutions, Malvern, PA (United States); Caruso, Damiano [Medical University of South Carolina, Division of Cardiovascular Imaging, Department of Radiology and Radiological Science, Charleston, SC (United States); University of Rome ' ' Sapienza' ' , Department of Radiological Sciences, Oncology and Pathology, Rome (Italy); Bamberg, Fabian; Nikolaou, Konstantin [Eberhard-Karls University Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany)

    2016-10-15

    To investigate the relationship between automated tube voltage selection (ATVS) and body mass index (BMI) and its effect on image quality and radiation dose of coronary CT angiography (CCTA). We evaluated 272 patients who underwent CCTA with 3{sup rd} generation dual-source CT (DSCT). Prospectively ECG-triggered spiral acquisition was performed with automated tube current selection and advanced iterative reconstruction. Tube voltages were selected by ATVS (70-120 kV). BMI, effective dose (ED), and vascular attenuation in the coronary arteries were recorded. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Five-point scales were used for subjective image quality analysis. Image quality was rated good to excellent in 98.9 % of examinations without significant differences for proximal and distal attenuation (all p ≥.0516), whereas image noise was rated significantly higher at 70 kV compared to ≥100 kV (all p <.0266). However, no significant differences were observed in SNR or CNR at 70-120 kV (all p ≥.0829). Mean ED at 70-120 kV was 1.5 ± 1.2 mSv, 2.4 ± 1.5 mSv, 3.6 ± 2.7 mSv, 5.9 ± 4.0 mSv, 7.9 ± 4.2 mSv, and 10.7 ± 4.1 mSv, respectively (all p ≤.0414). Correlation analysis showed a moderate association between tube voltage and BMI (r =.639). ATVS allows individual tube voltage adaptation for CCTA performed with 3{sup rd} generation DSCT, resulting in significantly decreased radiation exposure while maintaining image quality. (orig.)

  12. Diagnostic accuracy of dual-source CT coronary angiography in a population unselected for degree of coronary artery calcification and without heart rate modification

    International Nuclear Information System (INIS)

    Lin, C.-J.; Hsu, J.-C.; Lai, Y.-J.; Wang, K.-L.; Lee, J.-Y.; Li, A.-H.; Chu, S.-H.

    2010-01-01

    Aim: To assess the ability of coronary angiography performed using dual-source computed tomography (DSCT) to evaluate coronary artery disease (CAD) in a population with unselected heart rates and extensive coronary calcification. Materials and methods: Forty-four patients at intermediate to high risk for CAD underwent both DSCT coronary angiography and invasive coronary angiography (ICA) within 30 days. No beta blockers were administered prior to imaging. Image quality and quantitatively stenosis of all coronary segments with a diameter ≥1.5 mm were accessed. Patients were stratified according to mean heart rate (<70 versus ≥70 bpm) and heart rate variability (<10 versus ≥10 bpm). DSCT detection of coronary stenosis by segment, vessel, and patient characteristics were compared to the reference standard of ICA. Results: Diagnostic accuracy for all patients was high regarding sensitivity (97%), positive predictive value (PPV, 84.2%), and negative predictive value (NPV, 83.3%) but low regarding specificity (45.5%) with a moderate interobserver agreement (Kappa = 0.50). The accuracy for vessel-based diagnosis was high regarding sensitivity (96.6%), specificity (80.8%), PPV (80.3%), and NPV (96.7%). The segment-based diagnostic results revealed a moderate interobserver agreement for image quality and sensitivity, specificity, PPV and NPV for all segments of 66.9, 97.8, 90.8, and 89.9%, respectively. Conclusion: DSCT coronary angiography has high diagnostic accuracy in assessing CAD among patients at intermediate to high risk without using heart rate-modulating premedication. DSCT is not superior to ICA for diagnosis of calcified segments.

  13. Initial results of a new generation dual source CT system using only an in-plane comb filter for ultra-high resolution temporal bone imaging.

    Science.gov (United States)

    Meyer, Mathias; Haubenreisser, Holger; Raupach, Rainer; Schmidt, Bernhard; Lietzmann, Florian; Leidecker, Christianne; Allmendinger, Thomas; Flohr, Thomas; Schad, Lothar R; Schoenberg, Stefan O; Henzler, Thomas

    2015-01-01

    To prospectively evaluate radiation dose and image quality of a third generation dual-source CT (DSCT) without z-axis filter behind the patient for temporal bone CT. Forty-five patients were either examined on a first, second, or third generation DSCT in an ultra-high-resolution (UHR) temporal bone-imaging mode. On the third generation DSCT system, the tighter focal spot of 0.2 mm(2) removes the necessity for an additional z-axis-filter, leading to an improved z-axis radiation dose efficiency. Images of 0.4 mm were reconstructed using standard filtered-back-projection or iterative reconstruction (IR) technique for previous generations of DSCT and a novel IR algorithm for the third generation DSCT. Radiation dose and image quality were compared between the three DSCT systems. The statistically significantly highest subjective and objective image quality was evaluated for the third generation DSCT when compared to the first or second generation DSCT systems (all p generation examination as compared to the first and second generation DSCT. Temporal bone imaging without z-axis-UHR-filter and a novel third generation IR algorithm allows for significantly higher image quality while lowering effective dose when compared to the first two generations of DSCTs. • Omitting the z-axis-filter allows a reduction in radiation dose of 50% • A smaller focal spot of 0.2 mm (2) significantly improves spatial resolution • Ultra-high-resolution temporal-bone-CT helps to gain diagnostic information of the middle/inner ear.

  14. Prospective versus retrospective ECG gating for dual source CT of the coronary stent: Comparison of image quality, accuracy, and radiation dose

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Lei, E-mail: zhaolei219@sohu.com [Beijing Anzhen Hospital of the Capital University of Medical Sciences (China); Zhang Zhaoqi; Fan Zhanming; Yang Lin; Du Jing [Beijing Anzhen Hospital of the Capital University of Medical Sciences (China)

    2011-03-15

    Objective: To compare image quality, diagnostic accuracy and radiation dose of prospective and retrospective electrocardiogram (ECG) gated dual source computed tomography (DSCT) for the evaluation of the coronary stent, using conventional coronary angiography (CA) as a standard reference. Design, setting and patients: Sixty patients (heart rates {<=}70 bpm) with previous stent implantation who were scheduled for CA were divided in two groups, receiving either prospective or retrospective ECG gated DSCT separately. Two reviewers scored coronary stent image quality and evaluated stent lumen. Results: There was no significant difference in image quality between the two groups. In the prospective group, there were 86.4% (51/59) stents with interpretable images, in the retrospective group, there were 87.5% (49/56) stents with interpretable images. Image quality was not influenced by age, body mass index or heart rate in either group, but heart rate variability had a weak impact on the image quality of the prospective group. Image noise was higher in the prospective group, but this difference reached statistical significance only by using a smooth kernel reconstruction. Per-stent based sensitivity, specificity, and positive and negative predictive value were 100%, 84.1%, 68.2%, and 100%, respectively, in the prospective CT angiography group and 94.4%, 86.8%, 77.3%, and 97.1%, respectively, in the retrospective CT angiography group. There was a significant difference in the effective radiation dose between the two groups, mean effective dose in the prospective and retrospective group was 2.2 {+-} 0.5 mSv (1.5-3.2 mSv) and 14.6 {+-} 3.3 mSv (10.0-20.4 mSv) (p < .001) respectively. Conclusions: Compared with retrospective CT angiography, prospective CT angiography has a similar performance in assessing coronary stent patency, but a lower effective dose in selected patients with regular heart rates {<=}70 bpm.

  15. Single- and dual-energy CT of the abdomen: comparison of radiation dose and image quality of 2nd and 3rd generation dual-source CT

    Energy Technology Data Exchange (ETDEWEB)

    Wichmann, Julian L. [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt (Germany); Hardie, Andrew D.; Felmly, Lloyd M.; Perry, Jonathan D.; Varga-Szemes, Akos; De Cecco, Carlo N. [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Schoepf, U.J. [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Medical University of South Carolina, Division of Cardiology, Department of Medicine, Charleston, SC (United States); Mangold, Stefanie [University Hospital of Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany); Caruso, Damiano [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); University of Rome ' ' Sapienza' ' , Department of Radiological Sciences, Oncological and Pathological Sciences, Latina (Italy); Canstein, Christian [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Siemens Medical Solutions USA, Malvern, PA (United States); Vogl, Thomas J. [University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt (Germany)

    2017-02-15

    To compare single-energy (SECT) and dual-energy (DECT) abdominal CT examinations in matched patient cohorts regarding differences in radiation dose and image quality performed with second- and third-generation dual-source CT (DSCT). We retrospectively analysed 200 patients (100 male, 100 female; mean age 61.2 ± 13.5 years, mean body mass index 27.5 ± 3.8 kg/m{sup 2}) equally divided into four groups matched by gender and body mass index, who had undergone portal venous phase abdominal CT with second-generation (group A, 120-kV-SECT; group B, 80/140-kV-DECT) and third-generation DSCT (group C, 100-kV-SECT; group D, 90/150-kV-DECT). The radiation dose was normalised for 40-cm scan length. Dose-independent figure-of-merit (FOM) contrast-to-noise ratios (CNRs) were calculated for various organs and vessels. Subjective overall image quality and reader confidence were assessed. The effective normalised radiation dose was significantly lower (P < 0.001) in groups C (6.2 ± 2.0 mSv) and D (5.3 ± 1.9 mSv, P = 0.103) compared to groups A (8.8 ± 2.3 mSv) and B (9.7 ± 2.4 mSv, P = 0.102). Dose-independent FOM-CNR peaked for liver, kidney, and portal vein measurements (all P ≤ 0.0285) in group D. Subjective image quality and reader confidence were consistently rated as excellent in all groups (all ≥1.53 out of 5). With both DSCT generations, abdominal DECT can be routinely performed without radiation dose penalty compared to SECT, while third-generation DSCT shows improved dose efficiency. (orig.)

  16. Dual-Source Dual-Energy CT Angiography of the Supra-Aortic Arteries with Tin Filter: Impact of Tube Voltage Selection.

    Science.gov (United States)

    Korn, Andreas; Bender, Benjamin; Schabel, Christoph; Bongers, Malte; Ernemann, Ulrike; Claussen, Claus; Thomas, Christoph

    2015-06-01

    Automatic bone and plaque subtraction (BPS) in computed tomographic angiographic (CTA) examinations using dual-energy CT (DECT) remains challenging because of beam-hardening artifacts in the shoulder region and close proximity of the internal carotid artery to the base of the skull. The selection of the tube voltage combination in dual-source CT influences the spectral separation and the susceptibility for artifacts. The purpose of this study was to assess which tube voltage combination leads to an optimal image quality of head and neck DECT angiograms after bone subtraction. Fifty-one patients received tin-filter-enhanced DECT angiograms of the supra-aortic arteries using two voltage protocols: 24 patients were studied using 80/Sn140 kV and 27 using a 100/Sn140 kV protocol, both protocols with an additional tin filter. A commercially available DE-CTA BPS algorithm was used. Artificial vessel erosions in BPS maximum intensity projections (four-level Likert scale with CTA source data as reference) and vessel signal-to-noise ratio (SNR) were assessed in the level of the shoulders and the base of the skull in each patient and compared. At the level of the shoulder, 100/Sn140 kV achieved higher SNR (23.4 ± 6.4 at 80/Sn140 kV vs. 35.1 ± 11.8 at 100/Sn140 kV; P supra-aortic arteries than the 80/Sn140 kV protocol. Copyright © 2015 AUR. Published by Elsevier Inc. All rights reserved.

  17. Separation of hepatic iron and fat by dual-source dual-energy computed tomography based on material decomposition: an animal study.

    Directory of Open Access Journals (Sweden)

    Jing Ma

    Full Text Available OBJECTIVE: To explore the feasibility of dual-source dual-energy computed tomography (DSDECT for hepatic iron and fat separation in vivo. MATERIALS AND METHODS: All of the procedures in this study were approved by the Research Animal Resource Center of Shanghai Ruijin Hospital. Sixty rats that underwent DECT scanning were divided into the normal group, fatty liver group, liver iron group, and coexisting liver iron and fat group, according to Prussian blue and HE staining. The data for each group were reconstructed and post-processed by an iron-specific, three-material decomposition algorithm. The iron enhancement value and the virtual non-iron contrast value, which indicated overloaded liver iron and residual liver tissue, respectively, were measured. Spearman's correlation and one-way analysis of variance (ANOVA were performed, respectively, to analyze statistically the correlations with the histopathological results and differences among groups. RESULTS: The iron enhancement values were positively correlated with the iron pathology grading (r = 0.729, p<0.001. Virtual non-iron contrast (VNC values were negatively correlated with the fat pathology grading (r = -0.642,p<0.0001. Different groups showed significantly different iron enhancement values and VNC values (F = 25.308,p<0.001; F = 10.911, p<0.001, respectively. Among the groups, significant differences in iron enhancement values were only observed between the iron-present and iron-absent groups, and differences in VNC values were only observed between the fat-present and fat-absent groups. CONCLUSION: Separation of hepatic iron and fat by dual energy material decomposition in vivo was feasible, even when they coexisted.

  18. Direct costs and cost-effectiveness of dual-source computed tomography and invasive coronary angiography in patients with an intermediate pretest likelihood for coronary artery disease.

    Science.gov (United States)

    Dorenkamp, Marc; Bonaventura, Klaus; Sohns, Christian; Becker, Christoph R; Leber, Alexander W

    2012-03-01

    The study aims to determine the direct costs and comparative cost-effectiveness of latest-generation dual-source computed tomography (DSCT) and invasive coronary angiography for diagnosing coronary artery disease (CAD) in patients suspected of having this disease. The study was based on a previously elaborated cohort with an intermediate pretest likelihood for CAD and on complementary clinical data. Cost calculations were based on a detailed analysis of direct costs, and generally accepted accounting principles were applied. Based on Bayes' theorem, a mathematical model was used to compare the cost-effectiveness of both diagnostic approaches. Total costs included direct costs, induced costs and costs of complications. Effectiveness was defined as the ability of a diagnostic test to accurately identify a patient with CAD. Direct costs amounted to €98.60 for DSCT and to €317.75 for invasive coronary angiography. Analysis of model calculations indicated that cost-effectiveness grew hyperbolically with increasing prevalence of CAD. Given the prevalence of CAD in the study cohort (24%), DSCT was found to be more cost-effective than invasive coronary angiography (€970 vs €1354 for one patient correctly diagnosed as having CAD). At a disease prevalence of 49%, DSCT and invasive angiography were equally effective with costs of €633. Above a threshold value of disease prevalence of 55%, proceeding directly to invasive coronary angiography was more cost-effective than DSCT. With proper patient selection and consideration of disease prevalence, DSCT coronary angiography is cost-effective for diagnosing CAD in patients with an intermediate pretest likelihood for it. However, the range of eligible patients may be smaller than previously reported.

  19. Volumetric evaluation of dual-energy perfusion CT by the presence of intrapulmonary clots using a 64-slice dual-source CT

    International Nuclear Information System (INIS)

    Okada, Munemasa; Nakashima, Yoshiteru; Kunihiro, Yoshie; Nakao, Sei; Matsunaga, Naofumi; Morikage, Noriyasu; Sano, Yuichi; Suga, Kazuyoshi

    2013-01-01

    Background: Dual-energy perfusion CT (DE p CT) directly represents the iodine distribution in lung parenchyma and low perfusion areas caused by intrapulmonary clots (IPCs) are visualized as low attenuation areas. Purpose: To evaluate if volumetric evaluation of DE p CT can be used as a predictor of right heart strain by the presence of IPCs. Material and Methods: One hundred and ninety-six patients suspected of having acute pulmonary embolism (PE) underwent DE p CT using a 64-slice dual-source CT. DE p CT images were three-dimensionally reconstructed with four threshold ranges: 1-120 HU (V 120 ), 1-15 HU (V 15 ), 1-10 HU (V 10 ), and 1-5 HU (V 5 ). Each relative ratio per V 120 was expressed as the %V 15 , %V 10 , and %V 5 . Volumetric data-sets were compared with D-dimer, pulmonary arterial (PA) pressure, right ventricular (RV) diameter, RV/left ventricular (RV/LV) diameter ratio, PA diameter, and PA/aorta (PA/Ao) diameter ratio. The areas under the ROC curves (AUCs) were examined for their relationship to the presence of IPCs. This study was approved by the local ethics committee. Results: PA pressure and D-dimer were significantly higher in the patients who had IPCs. In the patients with IPCs, V 15 , V 10 , V 5 , %V 15 , %V 10 , and %V 5 were also significantly higher than those without IPC (P = 0.001). %V 5 had a better correlation with D-dimer (r = 0.30, P p CT had a correlation with D-dimer and RV/LV diameter ratio, and the relative ratio of volumetric CT measurements with a lower attenuation threshold might be recommended for the analysis of acute PE

  20. Radiation Dose Reduction of Chest CT with Iterative Reconstruction in Image Space - Part I: Studies on Image Quality Using Dual Source CT

    International Nuclear Information System (INIS)

    Hwang, Hye Jeon; Seo, Joon Beom; Lee, Jin Seong; Song, Jae Woo; Lee, Hyun Joo; Lim, Chae Hun; Kim, Song Soo

    2012-01-01

    To determine whether the image quality (IQ) is improved with iterative reconstruction in image space (IRIS), and whether IRIS can be used for radiation reduction in chest CT. Standard dose chest CT (SDCT) in 50 patients and low dose chest CT (LDCT) in another 50 patients were performed, using a dual-source CT, with 120 kVp and same reference mAs (50 mAs for SDCT and 25 mAs for LDCT) employed to both tubes by modifying a dual-energy scan mode. Full-dose data were obtained by combining the data from both tubes and half-dose data were separated from a single tube. These were reconstructed by using a filtered back projection (FBP) and IRIS: full-dose FBP (F-FBP); full-dose IRIS (F-IRIS); half-dose FBP (H-FBP) and half-dose IRIS (H-IRIS). Objective noise was measured. The subjective IQ was evaluated by radiologists for the followings: noise, contrast and sharpness of mediastinum and lung. Objective noise was significantly lower in H-IRIS than in F-FBP (p < 0.01). In both SDCT and LDCT, the IQ scores were highest in F-IRIS, followed by F-FBP, H-IRIS and H-FBP, except those for sharpness of mediastinum, which tended to be higher in FBP. When comparing CT images between the same dose and different reconstruction (F-IRIS/F-FBP and H-IRIS/H-FBP) algorithms, scores tended to be higher in IRIS than in FBP, being more distinct in half-dose images. However, despite the use of IRIS, the scores were lower in H-IRIS than in F-FBP. IRIS generally helps improve the IQ, being more distinct at the reduced radiation. However, reduced radiation by half results in IQ decrease even when using IRIS in chest CT.

  1. Improved assessment of mediastinal and pulmonary pathologies in combined staging CT examinations using a fast-speed acquisition dual-source CT protocol

    Energy Technology Data Exchange (ETDEWEB)

    Braun, Franziska M.; Holzner, Veronica; Meinel, Felix G.; Armbruster, Marco; Brandlhuber, Martina; Ertl-Wagner, Birgit; Sommer, Wieland H. [University Hospital Munich, Institute for Clinical Radiology, Munich (Germany)

    2017-12-15

    To demonstrate the feasibility of fast Dual-Source CT (DSCT) and to evaluate the clinical utility in chest/abdomen/pelvis staging CT studies. 45 cancer patients with two follow-up combined chest/abdomen/pelvis staging CT examinations (maximally ±10 kV difference in tube potential) were included. The first scan had to be performed with our standard protocol (fixed pitch 0.6), the second one using a novel fast-speed DSCT protocol (fixed pitch 1.55). Effective doses (ED) were calculated, noise measurements performed. Scan times were compared, motion artefacts and the diagnostic confidence rated in consensus reading. ED for the standard and fast-speed scans was 9.1 (7.0-11.1) mSv and 9.2 (7.4-12.8) mSv, respectively (P = 0.075). Image noise was comparable (abdomen; all P > 0.05) or reduced for fast-speed CTs (trachea, P = 0.001; ascending aorta, P < 0.001). Motion artefacts of the heart/the ascending aorta (all P < 0.001) and breathing artefacts (P < 0.031) were reduced in fast DSCT. The diagnostic confidence for the evaluation of mediastinal (P < 0.001) and pulmonary (P = 0.008) pathologies was improved for fast DSCT. Fast DSCT for chest/abdomen/pelvis staging CT examinations is performed within 2 seconds scan time and eliminates relevant intrathoracic motion/breathing artefacts. Mediastinal/pulmonary pathologies can thus be assessed with high diagnostic confidence. Abdominal image quality remains excellent. (orig.)

  2. Diagnostic accuracy of second-generation dual-source computed tomography coronary angiography with iterative reconstructions: a real-world experience.

    Science.gov (United States)

    Maffei, E; Martini, C; Rossi, A; Mollet, N; Lario, C; Castiglione Morelli, M; Clemente, A; Gentile, G; Arcadi, T; Seitun, S; Catalano, O; Aldrovandi, A; Cademartiri, F

    2012-08-01

    The authors evaluated the diagnostic accuracy of second-generation dual-source (DSCT) computed tomography coronary angiography (CTCA) with iterative reconstructions for detecting obstructive coronary artery disease (CAD). Between June 2010 and February 2011, we enrolled 160 patients (85 men; mean age 61.2±11.6 years) with suspected CAD. All patients underwent CTCA and conventional coronary angiography (CCA). For the CTCA scan (Definition Flash, Siemens), we use prospective tube current modulation and 70-100 ml of iodinated contrast material (Iomeprol 400 mgI/ ml, Bracco). Data sets were reconstructed with iterative reconstruction algorithm (IRIS, Siemens). CTCA and CCA reports were used to evaluate accuracy using the threshold for significant stenosis at ≥50% and ≥70%, respectively. No patient was excluded from the analysis. Heart rate was 64.3±11.9 bpm and radiation dose was 7.2±2.1 mSv. Disease prevalence was 30% (48/160). Sensitivity, specificity and positive and negative predictive values of CTCA in detecting significant stenosis were 90.1%, 93.3%, 53.2% and 99.1% (per segment), 97.5%, 91.2%, 61.4% and 99.6% (per vessel) and 100%, 83%, 71.6% and 100% (per patient), respectively. Positive and negative likelihood ratios at the per-patient level were 5.89 and 0.0, respectively. CTCA with second-generation DSCT in the real clinical world shows a diagnostic performance comparable with previously reported validation studies. The excellent negative predictive value and likelihood ratio make CTCA a first-line noninvasive method for diagnosing obstructive CAD.

  3. Xenon ventilation CT using dual-source and dual-energy technique in children with bronchiolitis obliterans: correlation of xenon and CT density values with pulmonary function test results

    International Nuclear Information System (INIS)

    Goo, Hyun Woo; Yang, Dong Hyun; Seo, Joon Beom; Chae, Eun Jin; Lee, Jeongjin; Hong, Soo-Jong; Yu, Jinho; Kim, Byoung-Ju; Krauss, Bernhard

    2010-01-01

    Xenon ventilation CT using dual-source and dual-energy technique is a recently introduced, promising functional lung imaging method. To expand its clinical applications evidence of additional diagnostic value of xenon ventilation CT over conventional chest CT is required. To evaluate the usefulness of xenon ventilation CT using dual-source and dual-energy technique in children with bronchiolitis obliterans (BO). Seventeen children (age 7-18 years; 11 boys) with BO underwent xenon ventilation CT using dual-source and dual-energy technique. Xenon and CT density values were measured in normal and hyperlucent lung regions on CT and were compared between the two regions. Volumes of hyperlucent regions and ventilation defects were calculated with thresholds determined by visual and histogram-based analysis. Indexed volumes of hyperlucent lung regions and ventilation defects were correlated with pulmonary function test results. Effective doses of xenon CT were calculated. Xenon (14.6 ± 6.4 HU vs 26.1 ± 6.5 HU; P 25-75 , (γ = -0.68-0.88, P ≤ 0.002). Volume percentages of xenon ventilation defects (35.0 ± 16.4%)] were not significantly different from those of hyperlucent lung regions (38.2 ± 18.6%). However, mismatches between the volume percentages were variable up to 21.4-33.3%. Mean effective dose of xenon CT was 1.9 ± 0.5 mSv. In addition to high-resolution anatomic information, xenon ventilation CT using dual-source and dual-energy technique demonstrates impaired regional ventilation and its heterogeneity accurately in children with BO without additional radiation exposure. (orig.)

  4. Coronary artery stent imaging with 128-slice dual-source CT using high-pitch spiral acquisition in a cardiac phantom: comparison with the sequential and low-pitch spiral mode

    International Nuclear Information System (INIS)

    Wolf, Florian; Loewe, Christian; Plank, Christina; Schernthaner, Ruediger; Bercaczy, Dominik; Lammer, Johannes; Leschka, Sebastian; Goetti, Robert; Marincek, Borut; Alkadhi, Hatem; Homolka, Peter; Friedrich, Guy; Feuchtner, Gudrun

    2010-01-01

    To evaluate coronary stents in vitro using 128-slice-dual-source computed tomography (CT). Twelve different coronary stents placed in a non-moving cardiac/chest phantom were examined by 128-slice dual-source CT using three CT protocols [high-pitch spiral (HPS), sequential (SEQ) and conventional spiral (SPIR)]. Artificial in-stent lumen narrowing (ALN), visible inner stent area (VIA), artificial in-stent lumen attenuation (ALA) in percent, image noise inside/outside the stent and CTDIvol were measured. Mean ALN was 46% for HPS, 44% for SEQ and 47% for SPIR without significant difference. Mean VIA was similar with 31% for HPS, 30% for SEQ and 33% for SPIR. Mean ALA was, at 5% for HPS, significantly lower compared with -11% for SPIR (p = 0.024), but not different from SEQ with -1%. Mean image noise was significantly higher for HPS compared with SEQ and SPIR inside and outside the stent (p < 0.001). CTDIvol was lower for HPS (5.17 mGy), compared with SEQ (9.02 mGy) and SPIR (55.97 mGy), respectively. The HPS mode of 128-slice dual-source CT yields fewer artefacts inside the stent lumen compared with SPIR and SEQ, but image noise is higher. ALN is still too high for routine stent evaluation in clinical practice. Radiation dose of the HPS mode is markedly (less than about tenfold) reduced. (orig.)

  5. Heating in toroidal plasmas

    International Nuclear Information System (INIS)

    Canobbio, E.

    1981-01-01

    This paper reports on the 2nd Joint Grenoble-Varenna International Symposium on Heating in Toroidal Plasmas, held at Como, Italy, from the 3-12 September 1980. Important problems in relation to the different existing processes of heating. The plasma were identified and discussed. Among others, the main processes discussed were: a) neutral beam heating, b) ion-(electron)-cyclotron resonance heating, c) hybrid resonance and low frequency heating

  6. On the Spatially Resolved Star Formation History in M51. I. Hybrid UV+IR Star Formation Laws and IR Emission from Dust Heated by Old Stars

    Science.gov (United States)

    Eufrasio, R. T.; Lehmer, B. D.; Zezas, A.; Dwek, E.; Arendt, R. G.; Basu-Zych, A.; Wiklind, T.; Yukita, M.; Fragos, T.; Hornschemeier, A. E.; Markwardt, L.; Ptak, A.; Tzanavaris, P.

    2017-12-01

    We present LIGHTNING, a new spectral energy distribution fitting procedure, capable of quickly and reliably recovering star formation history (SFH) and extinction parameters. The SFH is modeled as discrete steps in time. In this work, we assumed lookback times of 0-10 Myr, 10-100 Myr, 0.1-1 Gyr, 1-5 Gyr, and 5-13.6 Gyr. LIGHTNING consists of a fully vectorized inversion algorithm to determine SFH step intensities and combines this with a grid-based approach to determine three extinction parameters. We apply our procedure to the extensive far-UV-to-far-IR photometric data of M51, convolved to a common spatial resolution and pixel scale, and make the resulting maps publicly available. We recover, for M51a, a peak star formation rate (SFR) between 0.1 and 5 Gyr ago, with much lower star formation activity over the past 100 Myr. For M51b, we find a declining SFR toward the present day. In the outskirt regions of M51a, which includes regions between M51a and M51b, we recover an SFR peak between 0.1 and 1 Gyr ago, which corresponds to the effects of the interaction between M51a and M51b. We utilize our results to (1) illustrate how UV+IR hybrid SFR laws vary across M51 and (2) provide first-order estimates for how the IR luminosity per unit stellar mass varies as a function of the stellar age. From the latter result, we find that IR emission from dust heated by stars is not always associated with young stars and that the IR emission from M51b is primarily powered by stars older than 5 Gyr.

  7. Application of Dual-Source-Computed Tomography in Pediatric Cardiology in Children Within the First Year of Life.

    Science.gov (United States)

    Hausmann, P; Stenger, A; Dittrich, S; Cesnjevar, R; Rüffer, A; Hammon, M; Uder, M; Rompel, O; Glöckler, M

    2016-02-01

    To assess fields of application and value of dual source computed tomography (DSCT) for diagnostics and therapy in patients with congenital heart disease during their first year of life. Evaluation of image quality, surgical use and radiation exposure of 2nd and 3 rd generation DSCT. DSCT was applied in 118 cases between January 2012 and October 2014 for diagnostics of congenital heart defects. 2nd generation was used in 91 cases until April 2014 and 3 rd generation in 27 cases during the period thereafter. 3 D reconstructions of the image data were created for clinical diagnostics and planning of interventions. Image quality was assessed using a 4-point-scale. The visibility of the mammary arteries was analyzed, and signal-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR) were calculated. The usefulness of 3D-reconstructions for surgical planning was rated using a 5-point-scale. Radiation exposure and contrast dye consumption were determined. All cases were analyzed retrospectively. DSCT was successfully used in 118 cases. All image data obtained were interpretable. More than 60 percent of cases did not show any artifacts. The mammary arteries were visible down to the diaphragmatic arch in more than 80 percent of cases. Diagnostic value and surgical benefit were evaluated as "useful" or as "essential" in all cases. Median radiation dose was 0.4 mSv and 0.27 mSv for the 2nd and 3 rd generation DSCT, respectively. Consumption of contrast dye was 2 ml/kg in all cases. DSCT is a modern and extremely helpful technique for diagnostics and planning of interventions in patients with complex congenital heart defects. Extracardiac vascular structures in particular can be depicted three-dimensionally at high resolution. The use of iterative reconstruction with 3 rd generation DSCT yielded image quality similar to that of 2nd generation DSCT at considerably reduced radiation exposure level compared to 2nd generation DSCT. 3 rd generation DSCT is a low

  8. Free-breathing high-pitch 80 kVp dual-source computed tomography of the pediatric chest: Image quality, presence of motion artifacts and radiation dose

    Energy Technology Data Exchange (ETDEWEB)

    Bodelle, Boris, E-mail: bbodelle@googlemail.com; Fischbach, Constanze; Booz, Christian; Yel, Ibrahim; Frellesen, Claudia; Beeres, Martin; Vogl, Thomas J.; Scholtz, Jan-Erik

    2017-04-15

    Objectives: To investigate image quality, presence of motion artifacts and effects on radiation dose of 80 kVp high-pitch dual-source CT (DSCT) in combination with an advanced modeled iterative reconstruction algorithm (ADMIRE) of the pediatric chest compared to single-source CT (SSCT). Materials and methods: The study was approved by the institutional review board. Eighty-seven consecutive pediatric patients (mean age 9.1 ± 4.9 years) received either free-breathing high-pitch (pitch 3.2) chest 192-slice DSCT (group 1, n = 31) or standard-pitch (pitch 1.2) 128-slice SSCT (group 2, n = 56) with breathing-instructions by random assignment. Tube settings were similar in both groups with 80 kVp and 74 ref. mAs. Images were reconstructed using FBP for both groups. Additionally, ADMIRE was used in group 1. Effective thorax diameter, image noise, and signal-to-noise ratio (SNR) of the pectoralis major muscle and the thoracic aorta were calculated. Motion artifacts were measured as doubling boarders of the diaphragm and the heart. Images were rated by two blinded readers for overall image quality and presence of motion artifacts on 5-point-scales. Size specific dose estimates (SSDE, mGy) and effective dose (ED, mSv) were calculated. Results: Age and effective thorax diameter showed no statistically significant differences in both groups. Image noise and SNR were comparable (p > 0.64) for SSCT and DSCT with ADMIRE, while DSCT with FBP showed inferior results (p < 0.01). Motion artifacts were reduced significantly (p = 0.001) with DSCT. DSCT with ADMIRE showed the highest overall IQ (p < 0.0001). Radiation dose was lower for DSCT compared to SSCT (median SSDE: 0.82 mGy vs. 0.92 mGy, p < 0.02; median ED: 0.4 mSv vs. 0.48 mSv, p = 0.02). Conclusions: High-pitch 80 kVp chest DSCT in combination with ADMIRE reduces motion artifacts and increases image quality while lowering radiation exposure in free-breathing pediatric patients without sedation.

  9. Quantitative analysis of pulmonary artery and pulmonary collaterals in preoperative patients with pulmonary artery atresia using dual-source computed tomography

    International Nuclear Information System (INIS)

    Yin Lei; Lu, Bin; Han Lei; Wu Runze; Johnson, Laura; Xu Zhongying; Jiang Shiliang; Dai Ruping

    2011-01-01

    Objective: To evaluate the value of dual-source computed tomography (DSCT) in quantitatively measuring pulmonary arteries and major aortopulmonary collateral vessels in comparison with conventional angiographic (CA) on preoperative patients with pulmonary artery atresia and ventricular septal defect (PAA-VSD). Materials and methods: Twenty PAA-VSD patients who had complete imaging data of DSCT, CA and echocardiography (ECHO) studies were retrospectively analyzed. Using final clinical diagnosis as the standard, results of DSCT, CA and ECHO on the detection of cardiac malformations, measurement of diameters of pulmonary artery and collateral vessel, as well as the values of McGoon ratio, pulmonary arterial index (PAI) and total neopulmonary arterial index (TNPAI) were derived and compared. Results: In 20 patients, 51 of 54 (94.4%) cardiac malformations were visualized by DSCT, whereas 42 (77.8%) by ECHO (p = 0.027). Fourteen cases with aortopulmonary collateral vessels were all (100%) detected by DSCT, whereas 5 cases (35.7%) by ECHO (p = 0.001), and 13 cases (92.9%) by CA (p = 0.995). Sixteen cases with confluence of native pulmonary arteries were diagnosed by DSCT, whereas 10 cases by CA (p = 0.024). Measurement of the diameters of pulmonary arteries, collateral vessels, and descending aorta at the level of diaphragm were correlated well between DSCT and CA (r = 0.95-0.99). McGoon ratio (DSCT = 1.18 ± 0.60, CA = 1.23 ± 0.64), PAI (DSCT = 130.96 ± 99.38 mm 2 /m 2 , CA = 140.91 ± 107.87 mm 2 /m 2 ) and TNPAI (DSCT = 160.31 ± 125.62 mm 2 /m 2 , CA = 169.14 ± 122.81 mm 2 /m 2 ) were calculated respectively, without significant differences between DSCT and CA by paired t-tests (all p > 0.05). Conclusion: DSCT was efficient for evaluating and measuring native pulmonary artery and aortopulmonary collateral vessels prior to surgical procedures in PAA-VSD patients. Combined with echocardiography, DSCT showed potential to replace CA for evaluating pulmonary artery

  10. Influence of trigger type, tube voltage and heart rate on calcified plaque imaging in dual source cardiac computed tomography: phantom study

    International Nuclear Information System (INIS)

    Penzkofer, Tobias; Donandt, Eva; Isfort, Peter; Allmendinger, Thomas; Kuhl, Christiane K; Mahnken, Andreas H; Bruners, Philipp

    2014-01-01

    To investigate the impact of high pitch cardiac CT vs. retrospective ECG gated CT on the quantification of calcified vessel stenoses, with assessment of the influence of tube voltage, reconstruction kernel and heart rate. A 4D cardiac movement phantom equipped with three different plaque phantoms (12.5%, 25% and 50% stenosis at different calcification levels), was scanned with a 128-row dual source CT scanner, applying different trigger types (gated vs. prospectively triggered high pitch), tube voltages (100-120 kV) and heart rates (50–90 beats per minute, bpm). Images were reconstructed using different standard (B26f, B46f, B70f) and iterative (I26f, I70f) convolution kernels. Absolute and relative plaque sizes were measured and statistically compared. Radiation dose associated with the different methods (gated vs. high pitch, 100 kV vs. 120 kV) were compared. Compared to the known diameters of the phantom plaques and vessels both CT-examination techniques overestimated the degrees of stenoses. Using the high pitch CT-protocol plaques appeared larger (0.09 ± 0.31 mm, 2 ± 8 percent points, PP) in comparison to the ECG-gated CT-scans. Reducing tube voltage had a similar effect, resulting in higher grading of the same stenoses by 3 ± 8 PP. In turn, sharper convolution kernels lead to a lower grading of stenoses (differences of up to 5%). Pairwise comparison of B26f and I26f, B46f and B70f, and B70f and I70f showed differences of 0–1 ± 6–8 PP of the plaque depiction. Motion artifacts were present only at 90 bpm high pitch experiments. High-pitch protocols were associated with significantly lower radiation doses compared with the ECG-gated protocols (258.0 mGy vs. 2829.8 mGy CTDI vol , p ≤ 0.0001). Prospectively triggered high-pitch cardiac CT led to an overestimation of plaque diameter and degree of stenoses in a coronary phantom. This overestimation is only slight and probably negligible in a clinical situation. Even at higher heart rates high pitch CT

  11. Feasibility and evaluation of dual-source transmit 3D imaging of the orbits: Comparison to high-resolution conventional MRI at 3T

    Energy Technology Data Exchange (ETDEWEB)

    Seeger, Achim, E-mail: achim.seeger@gmx.de [Department of Diagnostic and Interventional Neuroradiology, Eberhard-Karls-University, Hoppe-Seyler-Str. 3, Tübingen 72076 (Germany); Schulze, Maximilian, E-mail: maximilian.schulze@med.uni-tuebingen.de [Department of Diagnostic and Interventional Neuroradiology, Eberhard-Karls-University, Hoppe-Seyler-Str. 3, Tübingen 72076 (Germany); Schuettauf, Frank, E-mail: fschuettauf@uni-tuebingen.de [University Eye Hospital, Department of Ophthalmology, Eberhard-Karls-University, Schleichstrasse 12, Tübingen 72076 (Germany); Klose, Uwe, E-mail: uwe.klose@med.uni-tuebingen.de [Department of Diagnostic and Interventional Neuroradiology, Eberhard-Karls-University, Hoppe-Seyler-Str. 3, Tübingen 72076 (Germany); Ernemann, Ulrike, E-mail: ulrike.ernemann@med.uni-tuebingen.de [Department of Diagnostic and Interventional Neuroradiology, Eberhard-Karls-University, Hoppe-Seyler-Str. 3, Tübingen 72076 (Germany); Hauser, Till-Karsten, E-mail: till-karsten.hauser@med.uni-tuebingen.de [Department of Diagnostic and Interventional Neuroradiology, Eberhard-Karls-University, Hoppe-Seyler-Str. 3, Tübingen 72076 (Germany)

    2015-06-15

    Highlights: • Reduced FOV imaging enables a 3D approach for a very fast assessment of the orbits. • Conventional MRI exhibited higher eSNR values and consecutively higher scores for overall image quality in the subjective readers’ analysis. • All pathologies could be detected compared to high-resolution conventional MRI making 3D pTX SPACE to a potential alternative and fast imaging technique. - Abstract: Purpose: To prospectively compare the image quality and diagnostic performance of orbital MR images obtained by using a dual-source parallel transmission (pTX) 3D sequence (Sampling Perfection with Application optimized Contrasts using different flip angle Evolution, SPACE) with the image quality of conventional high-resolution standard protocol for clinical use in patients at 3T. Materials and methods: After obtaining institutional review board approval and patient consent, 32 patients with clinical indication for orbital MRI were examined using a high-resolution conventional sequences and 3D pTX SPACE sequences. Quantitative measurements, image quality of the healthy orbit, incidence of artifacts, and the subjective diagnostic performance to establish diagnosis was rated. Statistical significance was calculated by using a Student's t-test and nonparametric Wilcoxon signed rank test. Results: Length measurements were comparable in the two techniques, 3D pTX SPACE resulted in significant faster image acquisition with higher spatial resolution and less motion artifacts as well as better delineation of the optic nerve sheath. However, estimated contrast-to-noise and signal-to-noise and overall image quality as well as subjective scores of the conventional TSE imaging were rated significantly higher. The conventional MR sequences were the preferred techniques by the readers. Conclusion: This study demonstrates the feasibility of 3D pTX SPACE of the orbit resulting in a rapid acquisition of isotropic high-resolution images. Although no pathology was

  12. Volumetric evaluation of dual-energy perfusion CT by the presence of intrapulmonary clots using a 64-slice dual-source CT

    Energy Technology Data Exchange (ETDEWEB)

    Okada, Munemasa; Nakashima, Yoshiteru; Kunihiro, Yoshie; Nakao, Sei; Matsunaga, Naofumi [Dept. of Radiology, Yamaguchi Univ. Graduate School of Medicine, Yamaguchi (Japan)], e-mail: radokada@yamaguchi-u.ac.jp; Morikage, Noriyasu [Medical Bioregulation Dept. of Organ Regulatory Surgery, Yamaguchi Univ. Graduate School of Medicine, Yamaguchi (Japan); Sano, Yuichi [Dept. of Radiology, Yamaguchi Univ. Hospital, Yamaguchi (Japan); Suga, Kazuyoshi [Dept. of Radiology, St Hills Hospital, Yamaguchi (Japan)

    2013-07-15

    Background: Dual-energy perfusion CT (DE{sub p}CT) directly represents the iodine distribution in lung parenchyma and low perfusion areas caused by intrapulmonary clots (IPCs) are visualized as low attenuation areas. Purpose: To evaluate if volumetric evaluation of DE{sub p}CT can be used as a predictor of right heart strain by the presence of IPCs. Material and Methods: One hundred and ninety-six patients suspected of having acute pulmonary embolism (PE) underwent DE{sub p}CT using a 64-slice dual-source CT. DE{sub p}CT images were three-dimensionally reconstructed with four threshold ranges: 1-120 HU (V{sub 120}), 1-15 HU (V{sub 15}), 1-10 HU (V{sub 10}), and 1-5 HU (V{sub 5}). Each relative ratio per V{sub 120} was expressed as the %V{sub 15}, %V{sub 10}, and %V{sub 5}. Volumetric data-sets were compared with D-dimer, pulmonary arterial (PA) pressure, right ventricular (RV) diameter, RV/left ventricular (RV/LV) diameter ratio, PA diameter, and PA/aorta (PA/Ao) diameter ratio. The areas under the ROC curves (AUCs) were examined for their relationship to the presence of IPCs. This study was approved by the local ethics committee. Results: PA pressure and D-dimer were significantly higher in the patients who had IPCs. In the patients with IPCs, V{sub 15}, V{sub 10}, V{sub 5}, %V{sub 15}, %V{sub 10}, and %V{sub 5} were also significantly higher than those without IPC (P = 0.001). %V{sub 5} had a better correlation with D-dimer (r = 0.30, P < 0.001) and RV/LV diameter ratio (r = 0.27, P < 0.001), and showed a higher AUC (0.73) than the other CT measurements. Conclusion: The volumetric evaluation by DE{sub p}CT had a correlation with D-dimer and RV/LV diameter ratio, and the relative ratio of volumetric CT measurements with a lower attenuation threshold might be recommended for the analysis of acute PE.

  13. Free-breathing high-pitch 80 kVp dual-source computed tomography of the pediatric chest: Image quality, presence of motion artifacts and radiation dose

    International Nuclear Information System (INIS)

    Bodelle, Boris; Fischbach, Constanze; Booz, Christian; Yel, Ibrahim; Frellesen, Claudia; Beeres, Martin; Vogl, Thomas J.; Scholtz, Jan-Erik

    2017-01-01

    Objectives: To investigate image quality, presence of motion artifacts and effects on radiation dose of 80 kVp high-pitch dual-source CT (DSCT) in combination with an advanced modeled iterative reconstruction algorithm (ADMIRE) of the pediatric chest compared to single-source CT (SSCT). Materials and methods: The study was approved by the institutional review board. Eighty-seven consecutive pediatric patients (mean age 9.1 ± 4.9 years) received either free-breathing high-pitch (pitch 3.2) chest 192-slice DSCT (group 1, n = 31) or standard-pitch (pitch 1.2) 128-slice SSCT (group 2, n = 56) with breathing-instructions by random assignment. Tube settings were similar in both groups with 80 kVp and 74 ref. mAs. Images were reconstructed using FBP for both groups. Additionally, ADMIRE was used in group 1. Effective thorax diameter, image noise, and signal-to-noise ratio (SNR) of the pectoralis major muscle and the thoracic aorta were calculated. Motion artifacts were measured as doubling boarders of the diaphragm and the heart. Images were rated by two blinded readers for overall image quality and presence of motion artifacts on 5-point-scales. Size specific dose estimates (SSDE, mGy) and effective dose (ED, mSv) were calculated. Results: Age and effective thorax diameter showed no statistically significant differences in both groups. Image noise and SNR were comparable (p > 0.64) for SSCT and DSCT with ADMIRE, while DSCT with FBP showed inferior results (p < 0.01). Motion artifacts were reduced significantly (p = 0.001) with DSCT. DSCT with ADMIRE showed the highest overall IQ (p < 0.0001). Radiation dose was lower for DSCT compared to SSCT (median SSDE: 0.82 mGy vs. 0.92 mGy, p < 0.02; median ED: 0.4 mSv vs. 0.48 mSv, p = 0.02). Conclusions: High-pitch 80 kVp chest DSCT in combination with ADMIRE reduces motion artifacts and increases image quality while lowering radiation exposure in free-breathing pediatric patients without sedation.

  14. Comprehensive low-dose imaging of carotid and coronary arteries with a single-injection dual-source CT angiography protocol

    International Nuclear Information System (INIS)

    Tognolini, A.; Arellano, C.S.; Marfori, W.; Heidari, G.; Sayre, J.W.; Krishnam, M.S.; Ruehm, S.G.

    2014-01-01

    Aim: To assess the feasibility of a fast single-bolus combined carotid and coronary computed tomography angiography (CTA) protocol in asymptomatic patients. Materials and methods: Thirty-three consecutive patients (18 women and 15 men) with a median age of 61 ± 14 years old (range 37–87 years) with known or suspected atherosclerotic disease were enrolled in this prospective study. A single breath-hold, single biphasic injection protocol (50 ml at 3 ml/s, 50 ml at 5 ml/s, 50 ml saline flush at 5 ml/s) was used for combined CTA imaging of the supra-aortic (SAA) and coronary arteries (CA) on a 64-slice dual-source CT (DSCT) machine. Helical CTA acquisition of the SAA was followed by prospective electrocardiography (ECG)-triggered coronary CTA. Subjective (four-point scale) image quality and objective signal-to-noise (SNR) and contrast-to-noise (CNR) measurements were performed. Vascular disease was graded on a four-point scale (grade 1: absent; grade 2: mild, grade 3: moderate; grade 4: severe). The radiation dose was recorded for each patient. Results: The average enhancement and subjective quality score of SAA and CA segments were 396 HU/358 HU and 1.2 ± 0.3/1.72 ± 0.4, respectively. The SNR was 27.1 ± 1.7 in the SAA and 21.6 ± 1.6 in the CA (p < 0.0001). The CNR was 18.1 ± 1.2 and 15.9 ± 1.8, respectively (p = 0.4). Four percent of SAA and 14% of CA segments (mostly due to peri-venous streak artefacts and small calibre, respectively) produced non-diagnostic images. SAA findings were as follows: 26/33 (79%) patients showed no disease and 6/33 (18%) had grade 2 and 1/33 (3%) had grade 3 disease. CA findings were as follows: 25/33 (76%) showed no disease and 6/33 (18%) patients had grade 2 and 2/33 (6%) had grade 3 disease. Five patients had disease in both districts. The average radiation dose for the combined CTA angiogram was 4.3 ± 0.6 mSv. Conclusion: A fast, low-dose combined DSCT angiography protocol appears technically feasible for imaging carotid and

  15. Comprehensive low-dose imaging of carotid and coronary arteries with a single-injection dual-source CT angiography protocol.

    Science.gov (United States)

    Tognolini, A; Arellano, C S; Marfori, W; Heidari, G; Sayre, J W; Krishnam, M S; Ruehm, S G

    2014-03-01

    To assess the feasibility of a fast single-bolus combined carotid and coronary computed tomography angiography (CTA) protocol in asymptomatic patients. Thirty-three consecutive patients (18 women and 15 men) with a median age of 61 ± 14 years old (range 37-87 years) with known or suspected atherosclerotic disease were enrolled in this prospective study. A single breath-hold, single biphasic injection protocol (50 ml at 3 ml/s, 50 ml at 5 ml/s, 50 ml saline flush at 5 ml/s) was used for combined CTA imaging of the supra-aortic (SAA) and coronary arteries (CA) on a 64-slice dual-source CT (DSCT) machine. Helical CTA acquisition of the SAA was followed by prospective electrocardiography (ECG)-triggered coronary CTA. Subjective (four-point scale) image quality and objective signal-to-noise (SNR) and contrast-to-noise (CNR) measurements were performed. Vascular disease was graded on a four-point scale (grade 1: absent; grade 2: mild, grade 3: moderate; grade 4: severe). The radiation dose was recorded for each patient. The average enhancement and subjective quality score of SAA and CA segments were 396 HU/358 HU and 1.2 ± 0.3/1.72 ± 0.4, respectively. The SNR was 27.1 ± 1.7 in the SAA and 21.6 ± 1.6 in the CA (p grade 2 and 1/33 (3%) had grade 3 disease. CA findings were as follows: 25/33 (76%) showed no disease and 6/33 (18%) patients had grade 2 and 2/33 (6%) had grade 3 disease. Five patients had disease in both districts. The average radiation dose for the combined CTA angiogram was 4.3 ± 0.6 mSv. A fast, low-dose combined DSCT angiography protocol appears technically feasible for imaging carotid and coronary atherosclerotic disease. Copyright © 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  16. An experimental and theoretical investigation on the effects of adding hybrid nanoparticles on heat transfer efficiency and pumping power of an oil-based nanofluid as a coolant fluid

    DEFF Research Database (Denmark)

    Asadi, Meisam; Asadi, Amin; Aberoumand, Sadegh

    2018-01-01

    The present work aims to study heat transfer performance and pumping power of MgO-MWCNT/ thermal oil hybrid nanofluid. Using a KD2 Pro thermal analyzer, the thermal conductivity of the samples have been measured. The results showed an increasing trend for the thermal conductivity of the nanofluid...... by increasing the mass concentration and temperature, in which the maximum enhancement of thermal conductivity was approximately 65%. Predicting the thermal conductivity of the nanofluid, a highly accurate correlation in terms of solid concentration and temperature has been proposed. Moreover, the heat transfer...... nanofluid is highly efficient in heat transfer applications as a coolant fluid in both the laminar and turbulent flow regimes, although it causes a certain penalty in the pumping power....

  17. Heating in toroidal plasmas

    International Nuclear Information System (INIS)

    Knoepfel, H.; Mazzitelli, G.

    1984-01-01

    The article is a rather detailed report on the highlights in the area of the ''Heating in toroidal plasmas'', as derived from the presentations and discussions at the international symposium with the same name, held in Rome, March 1984. The symposium covered both the physics (experiments and theory) and technology of toroidal fusion plasma heating. Both large fusion devices (either already in operation or near completion) requiring auxiliary heating systems at the level of tens of megawatts, as well as physics of their heating processes and their induced side effects (as studied on smaller devices), received attention. Substantial progress was reported on the broad front of auxiliary plasma heating and Ohmic heating. The presentation of the main conclusions of the symposium is divided under the following topics: neutral-beam heating, Alfven wave heating, ion cyclotron heating, lower hybrid heating, RF current drive, electron cyclotron heating, Ohmic heating and special contributions

  18. An experimental and theoretical investigation on the effects of adding hybrid nanoparticles on heat transfer efficiency and pumping power of an oil-based nanofluid as a coolant fluid

    DEFF Research Database (Denmark)

    Asadi, Meisam; Asadi, Amin; Aberoumand, Sadegh

    2018-01-01

    The present work aims to study heat transfer performance and pumping power of MgO-MWCNT/ thermal oil hybrid nanofluid. Using a KD2 Pro thermal analyzer, the thermal conductivity of the samples have been measured. The results showed an increasing trend for the thermal conductivity of the nanofluid...... nanofluid is highly efficient in heat transfer applications as a coolant fluid in both the laminar and turbulent flow regimes, although it causes a certain penalty in the pumping power....... efficiency and pumping power in all the studied range of solid concentrations and temperatures have been theoretically investigated, based on the experimental data of dynamic viscosity and thermal conductivity, for both the internal laminar and turbulent flow regimes. It was observed that the studied......The present work aims to study heat transfer performance and pumping power of MgO-MWCNT/ thermal oil hybrid nanofluid. Using a KD2 Pro thermal analyzer, the thermal conductivity of the samples have been measured. The results showed an increasing trend for the thermal conductivity of the nanofluid...

  19. Dual-source dual-energy CT angiography with virtual non-enhanced images and iodine map for active gastrointestinal bleeding: Image quality, radiation dose and diagnostic performance

    International Nuclear Information System (INIS)

    Sun, Hao; Hou, Xin-Yi; Xue, Hua-Dan; Li, Xiao-Guang; Jin, Zheng-Yu; Qian, Jia-Ming; Yu, Jian-Chun; Zhu, Hua-Dong

    2015-01-01

    Highlights: • GIB is a common gastrointestinal emergency with a high mortality rate. • Detection and localization of GIB source are important for imaging modality. • DSDECTA using a dual-phase scan protocol is clinically feasible. • DSDECTA with VNE and iodine map images can diagnose the active GIB source accurately. • DSDECTA can reduce radiation dose compared with conventional CT examination in GIB. - Abstract: Objectives: To evaluate the clinical feasibility of dual-source dual-energy CT angiography (DSDECTA) with virtual non-enhanced images and iodine map for active gastrointestinal bleeding (GIB). Methods: From June 2010 to December 2012, 112 consecutive patients with clinical signs of active GIB underwent DSDECTA with true non-enhanced (TNE), arterial phase with single-source mode, and portal-venous phase with dual-energy mode (100 kVp/230 mAs and Sn 140 kVp/178 mAs). Virtual non-enhanced CT (VNE) image sets and iodine map were reformatted from ‘Liver VNC’ software. The mean CT number, noise, signal to noise ratio (SNR), image quality and radiation dose were compared between TNE and VNE image sets. Two radiologists, blinded to clinical data, interpreted images from DSDECTA with TNE (protocol 1), and DSDECTA with VNE and iodine map (protocol 2) respectively, with discordant interpretation resolved by consensus. The standards of reference included digital subtraction angiography, endoscopy, surgery, or final pathology reports. Receiver–operating characteristic (ROC) analysis was undertaken and the area under the curve (AUC) calculated for CT protocols 1 and 2, respectively. Results: There was no significant difference in mean CT numbers of all organs (including liver, pancreas, spleen, kidney, abdominal aorta, and psoas muscle) (P > 0.05). Lower noise and higher SNR were found on VNE images than TNE images (P < 0.05). Image quality of VNE was lower than that of TNE without significant difference (P > 0.05). The active GIB source was identified

  20. Dual-source dual-energy CT angiography with virtual non-enhanced images and iodine map for active gastrointestinal bleeding: Image quality, radiation dose and diagnostic performance

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Hao, E-mail: sunhao_robert@126.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Hou, Xin-Yi, E-mail: hxy_pumc@126.com [Department of Radiology, Beijing Tiantan Hospital, Capital Medical University, Beijing (China); Xue, Hua-Dan, E-mail: bjdanna95@hotmail.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Li, Xiao-Guang, E-mail: xglee88@126.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Jin, Zheng-Yu, E-mail: zhengyu_jin@126.com [Department of Radiology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Shuaifuyuan No. 1, Wangfujing Street, Dongcheng District, Beijing 100730 (China); Qian, Jia-Ming, E-mail: qjiaming57@gmail.com [Department of Gastroenterology, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing (China); Yu, Jian-Chun, E-mail: yu-jch@163.com [Department of General Surgery, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing (China); Zhu, Hua-Dong, E-mail: huadongzhu@hotmail.com [Department of Emergency, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing (China)

    2015-05-15

    Highlights: • GIB is a common gastrointestinal emergency with a high mortality rate. • Detection and localization of GIB source are important for imaging modality. • DSDECTA using a dual-phase scan protocol is clinically feasible. • DSDECTA with VNE and iodine map images can diagnose the active GIB source accurately. • DSDECTA can reduce radiation dose compared with conventional CT examination in GIB. - Abstract: Objectives: To evaluate the clinical feasibility of dual-source dual-energy CT angiography (DSDECTA) with virtual non-enhanced images and iodine map for active gastrointestinal bleeding (GIB). Methods: From June 2010 to December 2012, 112 consecutive patients with clinical signs of active GIB underwent DSDECTA with true non-enhanced (TNE), arterial phase with single-source mode, and portal-venous phase with dual-energy mode (100 kVp/230 mAs and Sn 140 kVp/178 mAs). Virtual non-enhanced CT (VNE) image sets and iodine map were reformatted from ‘Liver VNC’ software. The mean CT number, noise, signal to noise ratio (SNR), image quality and radiation dose were compared between TNE and VNE image sets. Two radiologists, blinded to clinical data, interpreted images from DSDECTA with TNE (protocol 1), and DSDECTA with VNE and iodine map (protocol 2) respectively, with discordant interpretation resolved by consensus. The standards of reference included digital subtraction angiography, endoscopy, surgery, or final pathology reports. Receiver–operating characteristic (ROC) analysis was undertaken and the area under the curve (AUC) calculated for CT protocols 1 and 2, respectively. Results: There was no significant difference in mean CT numbers of all organs (including liver, pancreas, spleen, kidney, abdominal aorta, and psoas muscle) (P > 0.05). Lower noise and higher SNR were found on VNE images than TNE images (P < 0.05). Image quality of VNE was lower than that of TNE without significant difference (P > 0.05). The active GIB source was identified