WorldWideScience

Sample records for thermal cycling characteristics

  1. Thermal cycling characteristics of plasma synthesized mullite films

    Energy Technology Data Exchange (ETDEWEB)

    Monteiro, O.R.; Hou, P.Y.; Brown, I.G. [Lawrence Berkeley National Lab., CA (United States)

    1997-12-01

    The authors have developed a plasma-based technique for the synthesis of mullite and mullite-like films on silicon carbide substrate material. The method, which they refer to as MePIIID (for Metal Plasma Immersion Ion Implantation and Deposition), uses two vacuum arc plasma sources and simultaneous pulse biasing of the substrate in a low pressure oxygen atmosphere. The Al:Si ratio can be controlled via the separate plasma guns, and the film adhesion, structure and morphology can be controlled via the ion energy which in turn is controlled by the pulse bias voltage. The films are amorphous as-deposited, and crystalline mullite is formed by subsequent annealing at 1000 C for 2 hours in air. Adhesion between the aluminum-silicon oxide film and the substrate increases after this first annealing. They have tested the behavior of films when subjected to repetitive thermal cycling between room temperature and 1100 C, and found that the films retain their adhesion and quality. Here they review the plasma synthesis technique and the characteristics of the mullite films prepared in this way, and summarize the status of the thermal cycling experiments.

  2. Thermal cycling and electrochemical characteristics of solid oxide fuel cell supported on stainless steel with a new 3-phase composite anode

    Science.gov (United States)

    Dayaghi, Amir Masoud; Kim, Kun Joong; Kim, Sun Jae; Kim, Sunwoong; Bae, Hongyeul; Choi, Gyeong Man

    2017-06-01

    We report design, fabrication method, and fast thermal-cycling ability of solid oxide fuel cells (SOFCs) that use stainless steel (STS) as a support, and a new 3-phase anode. La and Ni co-doped SrTiO3 (La0.2Sr0.8Ti0.9Ni0.1O3-d, LSTN), replaces some of the Ni in conventional Ni-yttria stabilized zirconia (YSZ) anode; the resultant LSTN-YSZ-Ni 3-phase-composite anode is tested as a new reduction (or decomposition)-resistant anode of STS-supported SOFCs that can be co-fired with STS. A multi-layered cell with YSZ electrolyte (thickness ∼5 μm), composite anode, STS-cermet contact-layer, and STS support is designed, then fabricated by tape casting, lamination, and co-firing at 1250 °C in reducing atmosphere. The maximum power density (MPD) is 325 mW cm-2 at 650 °C; this is one of the highest among STS-supported cells fabricated by co-firing. The cell also shows stable open-circuit voltage and Ohmic resistance during 100 rapid thermal cycles between 170 and 600 °C. STS support minimizes stress and avoids cracking of electrolyte during rapid thermal cycling. The excellent MPD and stability during thermal cycles, and promising characteristics of SOFC as a power source for vehicle or mobile devices that requires rapid thermal cycles, are attributed to the new design of the cell with new anode structure.

  3. Characteristics of track cycling.

    Science.gov (United States)

    Craig, N P; Norton, K I

    2001-01-01

    Track cycling events range from a 200 m flying sprint (lasting 10 to 11 seconds) to the 50 km points race (lasting approximately 1 hour). Unlike road cycling competitions where most racing is undertaken at submaximal power outputs, the shorter track events require the cyclist to tax maximally both the aerobic and anaerobic (oxygen independent) metabolic pathways. Elite track cyclists possess key physical and physiological attributes which are matched to the specific requirements of their events: these cyclists must have the appropriate genetic predisposition which is then maximised through effective training interventions. With advances in technology it is now possible to accurately measure both power supply and demand variables under competitive conditions. This information provides better resolution of factors that are important for training programme design and skill development.

  4. Research on nanosatellite thermal cycling test applicability

    Directory of Open Access Journals (Sweden)

    Li Xiyuan

    2017-01-01

    Full Text Available In order to verify the spacecraft performance in extreme temperature and vacuum, and to screen spacecraft early defect, generally spacecraft TV (Thermal Vacuum test should be carried out before launch. Designed in small size and with low cost, nanosatellite is made from a large number of COTS (Commercial off the shelf components; therefore, the test should be low-cost, simple and quick. With the intention of screen out early defects of the product in lower cost, nanosatellite developers usually use TC (Thermal Cycling test to partially replace the TV test because TV test is more expensive. However, due to the air convection, TC test is different from TV test in heat transfer characteristics, which may be over-test or short-test in TC test. This paper aims to explore the applicability of different nanosatellites in TC/TV test. Using rule number analysis method, Heat Transfer model in vacuum and ambient environment has been built to analyse the characteristics of heat transfer under different temperature and characteristic length, and to deliver the recommended limits on using TC test instead of the TV test. The CFD and test methods are applied to verify the rule number analysis above.

  5. Thermal stress relaxation in magnesium composites during thermal cycling

    Energy Technology Data Exchange (ETDEWEB)

    Trojanova, Z.; Lukac, P. (Karlova Univ., Prague (Czech Republic)); Kiehn, J.; Kainer, K.U.; Mordike, B.L. (Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany))

    1998-01-01

    It has been shown that the internal friction of Mg - Saffil metal matrix composites can be influenced by thermal stresses, if MMCc are submitted to thermal cycling between room temperature and an upper temperature of cycling. These stresses can be accommodated by generation and motion of dislocations giving the formation of the microplastic zones. The thermal stress relaxation depends on the upper temperature of cycling, the volume fraction of reinforcement and the matrix composition and can result in plastic deformation and strain hardening of the matrix without applied stress. The internal friction measurements can be used for non destructive investigation of processes which influence the mechanical properties. (orig.)

  6. Ultrafast Thermal Cycling of Solar Panels

    National Research Council Canada - National Science Library

    Wall, T

    1998-01-01

    Two new cyclers that utilize a novel hybrid approach to perform fast thermal cycling of solar panels have been built and are now operational in the Mechanics and Materials Technology Center at The Aerospace Corporation...

  7. Methods and compositions for rapid thermal cycling

    Science.gov (United States)

    Beer, Neil Reginald; Benett, William J.; Frank, James M.; Deotte, Joshua R.; Spadaccini, Christopher

    2015-10-27

    The rapid thermal cycling of a material is targeted. A microfluidic heat exchanger with an internal porous medium is coupled to tanks containing cold fluid and hot fluid. Fluid flows alternately from the cold tank and the hot tank into the porous medium, cooling and heating samples contained in the microfluidic heat exchanger's sample wells. A valve may be coupled to the tanks and a pump, and switching the position of the valve may switch the source and direction of fluid flowing through the porous medium. A controller may control the switching of valve positions based on the temperature of the samples and determined temperature thresholds. A sample tray for containing samples to be thermally cycled may be used in conjunction with the thermal cycling system. A surface or internal electrical heater may aid in heating the samples, or may replace the necessity for the hot tank.

  8. Damage Assessment of Stress-Thermal Cycled high temperature

    Science.gov (United States)

    Ju, Jae-Hyung; Prochazka, Michael; Ronke, Ben; Morgan, Roger; Shin, Eugence

    2004-01-01

    We report on the characterization of bismaleimide and polyimide carbon fiber composite, microcrack development under stress thermal cycling loading. Such cycles range from cryogenic temperatures associated with cryogenic fuel (LN, LOX) containment to high temperatures of 300 degrees Celsius associated with future hypervelocity aeropropulsion systems. Microcrack development thresholds as a function of temperature range of the thermal cycle; the number of cycles; the applied stress level imposed on the composite are reported. We have conducted stress-thermal cycles on thin bismaleimide-woven carbon fiber foils for three temperature range cycles: 1. Ambient temperature - -196 degrees celsius. 2. Ambient temperature - 150 degrees Celsius; 200 degrees Celsius; 250 degrees Celsius. 3. -196 degrees Celsius - 250 degrees Celsius. The Principle findings are that the full cycles from -196 degrees Celsius to to 250 degrees Celsius cause the most significant microcrack of development. These observations indicate that the high temperature portion of the cycle under load causes fiber-matrix interface failure and subsequent exposure to higher stresses at the cryogenic, low temperature region results in composite matrix microcracking as a result of the additional stresses associate with the fiber-matrix thermal expansion mismatch. Our initial studies for 12 ply PMR-II-50 polyimide/M60JB carbon fabric [0f,90f,90f,0f,0f,90f]ls composites will be presented. The stress-thermal cycle test procedure for these will be described. Moisture absorption characteristics between cycles will be used to monitor interconnected microcrack development. The applied stress level will be 75% of the composite cryogenic (-196 degrees Celsius) ultimate strength.

  9. Growth of Creamed TNT on Thermal Cycling

    Science.gov (United States)

    1978-07-01

    on this page): No Limitation 14. DESCRIPTORS: Explosives ; Trinitrotoluene; Growth; Thermal Cycling; Thermal Expansion; Impurities; Eutectics. T5...Apparatus 2 2. Materials 2 RESULTS 3 Series 1 3 Series 2 4 Series 3 5 Observations from Dilatometer Rprnreig 5 Surface Changes Accompanying Growth 6...filling prematures than similar rounds which have not. It was proposed that this desensitisation might be a result of the explosive expanding

  10. Influence of Thermal Cycling on Cryogenic Thermometers

    CERN Document Server

    Balle, C; Rieubland, Jean Michel; Suraci, A; Togny, F; Vauthier, N

    1999-01-01

    The stringent requirements on temperature control of the superconducting magnets for the Large Hadron Collider (LHC), impose that the cryogenic temperature sensors meet compelling demands such as long-term stability, radiation hardness, readout accuracy better than 5 mK at 1.8 K and compatibility with industrial control equipment. This paper presents the results concerning long-term stability of resistance temperature sensors submitted to cryogenic thermal cycles. For this task a simple test facility has been designed, constructed and put into operation for cycling simultaneously 115 cryogenic thermometers between 300 K and 4.2 K. A thermal cycle is set to last 71/4 hours: 3 hours for either cooling down or warming up the sensors and 1 respectively 1/4 hour at steady temperature conditions at each end of the temperature cycle. A Programmable Logic Controller (PLC) drives automatically this operation by reading 2 thermometers and actuating on 3 valves and 1 heater. The first thermal cycle was accomplished in a...

  11. Weldability prediction of high strength steel S960QL after weld thermal cycle simulation

    Directory of Open Access Journals (Sweden)

    M. Dunđer

    2014-10-01

    Full Text Available This paper presents weld thermal cycle simulation of high strength steel S960QL, and describes influence of cooling time t8/5 on hardness and impact toughness of weld thermal cycle simulated specimens. Furthermore, it presents analysis of characteristic fractions done by electron scanning microscope which can contribute to determination of welding parameters for S960QL steel.

  12. THERMAL DRIFT CHARACTERISTICS OF CAPACITIVE PRESSURE SENSORS

    OpenAIRE

    ABDELAZIZ BEDDIAF; FOUAD KERROUR; SALAH KEMOUCHE

    2016-01-01

    The capacitive pressure sensors based on silicon are characterized by their very high sensitivities and their low power consumption. Nevertheless, their thermal behavior remains more or less unpredictable because they can indicate very high thermal coefficients. The study of the thermal behavior of these sensors is essential to define the parameters that cause the output characteristics drift. In this study, we modeled the thermal behavior of this sensors, using Finite Element Analysis (FE...

  13. Exploring cycle crash characteristics in Malaysia

    Directory of Open Access Journals (Sweden)

    Hamzah A.

    2017-01-01

    Full Text Available This paper explains the cycle road crash trend, characteristics and injuries in Malaysia. It analyses the in-depth road crash investigation data collected by the Royal Malaysian Police which was made available to MIROS crash database. Fatality data was utilized due to its consistency. Cycle casualties reflected a continual downward pattern for year 2009 to 2014 in which the number of cycle crash involvement reduced by 49% and fatalities dropped by 42%. Among the prevalent factors of cycle fatalities are >60 age group, federal and state roads and straight road sections, rural and small towns, evening peak hours, and mainly involving cars and motorcycles. It is hoped that all these information would spark interests to improve cycle safety in Malaysia.

  14. Thermal Characteristics of Urban Landscapes

    Science.gov (United States)

    Luvall, Jeffrey C.; Quattrochi, Dale A.

    1998-01-01

    Although satellite data are very useful for analysis of the urban heat island effect at a coarse scale, they do not lend themselves to developing a better understanding of which surfaces across the city contribute or drive the development of the urban heat island effect. Analysis of thermal energy responses for specific or discrete surfaces typical of the urban landscape (e.g., asphalt, building rooftops, vegetation) requires measurements at a very fine spatial scale (i.e., less than 15 m) to adequately resolve these surfaces and their attendant thermal energy regimes. Additionally, very fine scale spatial resolution thermal infrared data, such as that obtained from aircraft, are very useful for demonstrating to planning officials, policy makers, and the general populace the benefits of the urban forest. These benefits include mitigating the urban heat island effect, making cities more aesthetically pleasing and more habitable environments, and aid in overall cooling of the community. High spatial resolution thermal data are required to quantify how artificial surfaces within the city contribute to an increase in urban heating and the benefit of cool surfaces (e.g., surface coatings that reflect much of the incoming solar radiation as opposed to absorbing it thereby lowering urban temperatures). The TRN (thermal response number) is a technique using aircraft remotely sensed surface temperatures to quantify the thermal response of urban surfaces. The TRN was used to quantify the thermal response of various urban surface types ranging from completely vegetated surfaces to asphalt and concrete parking lots for Huntsville, AL.

  15. Characteristics of Menstrual Cycle in Shift Workers

    Science.gov (United States)

    Attarchi, Mirsaeed; Darkhi, Hamidreza; Kashanian, Maryam; khodarahmian, Mahshad; Dolati, Mandana; Ghaffari, Mostafa; Mirzamohammadi, Elham; Mohammadi, Saber

    2013-01-01

    Background: In this study, the characteristics of menstrual cycle in shift workers employed in the pharmaceutical industry are investigated. Method: This study was conducted in a pharmaceutical industrial complex in Tehran in 2012. 406 female workers in packaging units were studied on the menstrual cycle characteristics. The studied workers were divided into two groups of shift workers and non-shift workers and were compared in terms of the frequency of menstrual disorder (short-term cycle, long-term cycle, irregular cycle and bleeding during menstrual cycle) as well as hormonal values (FSH, LH, TSH, and Prolactin). Results: The odds ratio (OR) for menstrual disorder in the shift workers was 5.54 (95% CI=2.78-11.02) compared to the non-shift workers. The mean difference of hormonal values (except prolactin) between shift workers and non-shift workers was not significant (P> 0.05). Conclusion: This study suggests that shift work may disrupt the menstrual cycle. PMID:23618486

  16. Thermal stress cycling of GaAs solar cells

    Science.gov (United States)

    Janousek, B. K.; Francis, R. W.; Wendt, J. P.

    1985-01-01

    A thermal cycling experiment was performed on GaAs solar cells to establish the electrical and structural integrity of these cells under the temperature conditions of a simulated low-Earth orbit of 3-year duration. Thirty single junction GaAs cells were obtained and tests were performed to establish the beginning-of-life characteristics of these cells. The tests consisted of cell I-V power output curves, from which were obtained short-circuit current, open circuit voltage, fill factor, and cell efficiency, and optical micrographs, spectral response, and ion microprobe mass analysis (IMMA) depth profiles on both the front surfaces and the front metallic contacts of the cells. Following 5,000 thermal cycles, the performance of the cells was reexamined in addition to any factors which might contribute to performance degradation. It is established that, after 5,000 thermal cycles, the cells retain their power output with no loss of structural integrity or change in physical appearance.

  17. THERMAL DRIFT CHARACTERISTICS OF CAPACITIVE PRESSURE SENSORS

    Directory of Open Access Journals (Sweden)

    ABDELAZIZ BEDDIAF

    2016-03-01

    Full Text Available The capacitive pressure sensors based on silicon are characterized by their very high sensitivities and their low power consumption. Nevertheless, their thermal behavior remains more or less unpredictable because they can indicate very high thermal coefficients. The study of the thermal behavior of these sensors is essential to define the parameters that cause the output characteristics drift. In this study, we modeled the thermal behavior of this sensors, using Finite Element Analysis (FEA made in COMSOL. The model solved by COMSOL environment takes into account the entire sensor and thermal effects due to the temperature considering the materials’ properties, the geometric shape and also the heat transfer mechanisms. By COMSOL we determine how the temperature affects the sensor during the manufacturing process. For that end, we calculated the thermal drift of capacitance at rest, the thermal coefficients and we compared them with experimental results to validate our model. Further, we studied the thermal drift of sensor characteristics both at rest and under constant and uniform pressure. Further, our study put emphasis on the geometric influence parameters on these characteristics to optimize the sensor performance. Finally, this study allows us to predict the sensor behavior against temperature and to minimize this effect by optimizing the geometrical parameters.

  18. SRF Performance of CEBAF After Thermal Cycle to Ambient Temperature

    CERN Document Server

    Rimmer, Robert; Preble, Joseph P; Reece, Charles E

    2005-01-01

    In September 2003, in the wake of Hurricane Isabel, JLab was without power for four days after a tree fell on the main power lines feeding the site. This was long enough to lose insulating vacuum in the cryomodules and cryogenic systems resulting in the whole accelerator warming up and the total loss of the liquid helium inventory. This thermal cycle stressed many of the cryomodule components causing several cavities to become inoperable due to helium to vacuum leaks. At the same time the thermal cycle released years of adsorbed gas from the cold surfaces. Over the next days and weeks this gas was pumped away, the insulating vacuum was restored and the machine was cooled back down and re-commissioned. In a testament to the robustness of SRF technology, only a small loss in energy capability was apparent, although individual cavities had quite different field-emission characteristics compared to before the event. In Summer 2004 a section of the machine was again cycled to room temperature during the long maint...

  19. Analysis of Thermal Performance in a Bidirectional Thermocycler by Including Thermal Contact Characteristics

    Directory of Open Access Journals (Sweden)

    Jyh Jian Chen

    2014-12-01

    Full Text Available This paper illustrates an application of a technique for predicting the thermal characteristics of a bidirectional thermocycling device for polymerase chain reaction (PCR. The micromilling chamber is oscillated by a servo motor and contacted with different isothermal heating blocks to successfully amplify the DNA templates. Because a comprehensive database of contact resistance factors does not exist, it causes researchers to not take thermal contact resistance into consideration at all. We are motivated to accurately determine the thermal characteristics of the reaction chamber with thermal contact effects existing between the heater surface and the chamber surface. Numerical results show that the thermal contact effects between the heating blocks and the reaction chamber dominate the temperature variations and the ramping rates inside the PCR chamber. However, the influences of various temperatures of the ambient conditions on the sample temperature during three PCR steps can be negligible. The experimental temperature profiles are compared well with the numerical simulations by considering the thermal contact conductance coefficient which is empirical by the experimental fitting. To take thermal contact conductance coefficients into consideration in the thermal simulation is recommended to predict a reasonable temperature profile of the reaction chamber during various thermal cycling processes. Finally, the PCR experiments present that Hygromycin B DNA templates are amplified successfully. Furthermore, our group is the first group to introduce the thermal contact effect into theoretical study that has been applied to the design of a PCR device, and to perform the PCR process in a bidirectional thermocycler.

  20. Method of systematic determination of specific thermal characteristics of building

    Directory of Open Access Journals (Sweden)

    Prokhorov Vitaliy

    2016-01-01

    Full Text Available In the paper the classical term «specific thermal characteristics of building» proposed by professor Chaplin V.M. for heating systems developing also for others heat-consuming system for building such as ventilation, air conditioning, hot-water supply system is observed. The followings attributing values are established: external building volume, temperature potential in annual crevice cycle.

  1. Thermally regenerative hydrogen/oxygen fuel cell power cycles

    Science.gov (United States)

    Morehouse, J. H.

    1986-01-01

    Two innovative thermodynamic power cycles are analytically examined for future engineering feasibility. The power cycles use a hydrogen-oxygen fuel cell for electrical energy production and use the thermal dissociation of water for regeneration of the hydrogen and oxygen. The TDS (thermal dissociation system) uses a thermal energy input at over 2000 K to thermally dissociate the water. The other cycle, the HTE (high temperature electrolyzer) system, dissociates the water using an electrolyzer operating at high temperature (1300 K) which receives its electrical energy from the fuel cell. The primary advantages of these cycles is that they are basically a no moving parts system, thus having the potential for long life and high reliability, and they have the potential for high thermal efficiency. Both cycles are shown to be classical heat engines with ideal efficiency close to Carnot cycle efficiency. The feasibility of constructing actual cycles is investigated by examining process irreversibilities and device efficiencies for the two types of cycles. The results show that while the processes and devices of the 2000 K TDS exceed current technology limits, the high temperature electrolyzer system appears to be a state-of-the-art technology development. The requirements for very high electrolyzer and fuel cell efficiencies are seen as determining the feasbility of the HTE system, and these high efficiency devices are currently being developed. It is concluded that a proof-of-concept HTE system experiment can and should be conducted.

  2. Effect of thermal state and thermal comfort on cycling performance in the heat

    NARCIS (Netherlands)

    Schulze, E.; Daanen, H.A.M.; Levels, K.; Casadio, J.R.; Plews, D.J.; Kliding, A.E.; Siegel, R.; Laursen, P.B.

    2015-01-01

    Purpose: To determine the effect of thermal state and thermal comfort on cycling performance in the heat. Methods: Seven well-trained male triathletes completed 3 performance trials consisting of 60 min cycling at a fixed rating of perceived exertion (14) followed immediately by a 20-km time trial

  3. Fast thermal cycling-enhanced electromigration in power metallization

    NARCIS (Netherlands)

    Nguyen, Van Hieu; Salm, Cora; Krabbenborg, B.H.; Krabbenborg, B.H.; Bisschop, J.; Mouthaan, A.J.; Kuper, F.G.

    Fast thermal nterconnects used in power ICs are susceptible to short circuit failure due to a combination of fast thermal cycling and electromigration stresses. In this paper, we present a study of electromigration-induced extrusion short-circuit failure in a standard two level metallization

  4. Eutectic mixtures of some fatty acids for latent heat storage: Thermal properties and thermal reliability with respect to thermal cycling

    Energy Technology Data Exchange (ETDEWEB)

    Sari, Ahmet [Department of Chemistry, Gaziosmanpasa University, 60240 Tokat (Turkey)]. E-mail: asari@gop.edu.tr

    2006-06-15

    Accelerated thermal cycle tests have been conducted to study the change in melting temperatures and latent heats of fusion of the eutectic mixtures of lauric acid (LA)-myristic acid (MA), lauric acid (LA)-palmitic acid (PA) and myristic acid (MA)-stearic acid (SA) as latent heat storage materials. The thermal properties of these materials were determined by the differential scanning calorimetry (DSC) analysis method. The thermal reliability of the eutectic mixtures after melt/freeze cycles of 720, 1080 and 1460 was also evaluated using the DSC curves. The accelerated thermal cycle tests indicate that the melting temperatures usually tend to decrease, and the variations in the latent heats of fusion are irregular with increasing number of thermal cycles. Moreover, the probable reasons for the change in thermal properties of the eutectic mixtures after repeated thermal cycles were investigated. Fourier Transform Infrared (FT-IR) spectroscopic analysis indicates that the accelerated melt/freeze processes do not cause any degradation in the chemical structure of the mixtures. The change in thermal properties of the eutectic mixtures with increasing number of thermal cycles is only because of the presence of certain amounts of impurities in the fatty acids used in their preparation. It is concluded that the tested eutectic mixtures have reasonable thermal properties and thermal reliability as phase change materials (PCMs) for latent heat storage in any solar heating applications that include a four year utilization period.

  5. Study on durability for thermal cycle of planar SOFC

    Energy Technology Data Exchange (ETDEWEB)

    Ando, Motoo; Nakata, Kei-ichi; Wakayama, Sin-ichi [Tonen Corp., Saitama (Japan)] [and others

    1996-12-31

    TONEN CORPORATION has developed planar type SOFC since 1986. We demonstrated the output of 1.3 kW in 1991 and 5.1 kW in 1995. Simultaneously we have studied how to raise electric efficiency and reliability utilizing hydrogen and propane as fuel. Durability for thermal cycle is one of the most important problems of planar SOFC to make it more practical. The planar type SOFC is made up of separator, zirconia electrolyte and glass sealant. The thermal expansion of these components are expected to be the same value, however, they still possess small differences. In this situation, a thermal cycle causes a thermal stress due to the difference of the cell components and is often followed by a rupture in cell components, therefore, the analysis of the thermal stress should give us much useful information. The thermal cycle process consists of a heating up and cooling down procedure. Zirconia electrolyte is not bonded to the separator under the condition of the initial heating up procedure, and glass sealant becomes soft or melts and glass seals spaces between the zirconia and separator. The glass sealant becomes harder with the cooling down procedure. Moreover, zirconia is tightly bonded with separator below a temperature which is defined as a constraint temperature and thermal stress also occurs. This indicates that the heating up process relaxes the thermal stress and the cooling down increases it. In this paper, we simulated dependence of the stress on the sealing configuration, thermal expansion of sealant and constraint temperature of sealant glass. Furthermore, we presented SOFC electrical properties after a thermal cycle.

  6. The universal power and efficiency characteristics for irreversible reciprocating heat engine cycles

    CERN Document Server

    Qin Xiao Yong; Sun Feng Rui; Wu Chih

    2003-01-01

    The performance of irreversible reciprocating heat engine cycles with heat transfer loss and friction-like term loss is analysed using finite-time thermodynamics. The universal relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, and the optimal relation between power output and the efficiency of the cycles are derived. Moreover, analysis and optimization of the model were carried out in order to investigate the effect of cycle processes on the performance of the cycle using numerical examples. The results obtained herein include the performance characteristics of irreversible reciprocating Diesel, Otto, Atkinson and Brayton cycles.

  7. Heat Transfer Characteristics of Tubular Thermal Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hei Cheon; Park, Sang Kyoo [Chonnam National Univ., Yeosu (Korea, Republic of); Ra, Beong Yeol [Sinsung Plant company, Ansan (Korea, Republic of)

    2007-07-01

    Heat transfer augmentation based on the process intensification concept in heat exchangers and thermal reactors has received much attention in recent years, mainly due to energy efficiency and environmental considerations. The concept consists of the development of novel apparatuses and techniques that, compared to those commonly used today, are expected to bring dramatic improvements in manufacturing and processing, substantially decreasing equipment size, energy consumption, and ultimately resulting in cheaper, sustainable technologies. The objective of this paper was to investigate the heat transfer characteristics of tubular thermal reactor using static mixing technology. Glycerin and water were used as the test fluids and water was used as the heating source. The results for heat transfer rate were strongly influenced by tube geometry and flow conditions.

  8. Accelerated Thermal Cycling Test of Microencapsulated Paraffin Wax/Polyaniline Made by Simple Preparation Method for Solar Thermal Energy Storage

    Directory of Open Access Journals (Sweden)

    Mohammad Mehrali

    2013-04-01

    Full Text Available Microencapsulated paraffin wax/polyaniline was prepared using a simple in situ polymerization technique, and its performance characteristics were investigated. Weight losses of samples were determined by Thermal Gravimetry Analysis (TGA. The microencapsulated samples with 23% and 49% paraffin showed less decomposition after 330 °C than with higher percentage of paraffin. These samples were then subjected to a thermal cycling test. Thermal properties of microencapsulated paraffin wax were evaluated by Differential Scanning Calorimeter (DSC. Structure stability and compatibility of core and coating materials were also tested by Fourier transform infrared spectrophotometer (FTIR, and the surface morphology of the samples are shown by Field Emission Scanning Electron Microscopy (FESEM. It has been found that the microencapsulated paraffin waxes show little change in the latent heat of fusion and melting temperature after one thousand thermal recycles. Besides, the chemical characteristics and structural profile remained constant after one thousand thermal cycling tests. Therefore, microencapsulated paraffin wax/polyaniline is a stable material that can be used for thermal energy storage systems.

  9. Effects of thermal cycling on aluminum metallization of power diodes

    DEFF Research Database (Denmark)

    Brincker, Mads; Pedersen, Kristian Bonderup; Kristensen, Peter Kjær

    2015-01-01

    Reconstruction of aluminum metallization on top of power electronic chips is a well-known wear out phenomenon under power cycling conditions. However, the origins of reconstruction are still under discussion. In the current study, a method for carrying out passive thermal cycling of power diodes...... is controlled and the device is not subjected to a current load the observed degradation of metallization and corresponding increase of resistance is purely induced by thermo-mechanical stress. A correlation between number of cycles, micro-structural evolution, and sheet resistance is found and conclusions...

  10. Weldability investigation steel P 91 by weld thermal cycle simulation

    Directory of Open Access Journals (Sweden)

    M. Dunđer

    2015-07-01

    Full Text Available This paper elaborates results of hardness and impact energy of thermal cycle simulated specimens of high-alloy steel P 91 and their dependence on cooling time from 800 to 500 °C. Results were obtained by measuring hardness HV 1 and by experimental testing of Charpy notched specimens. Metallographic analysis of samples was performed on scanning electronic microscope.

  11. A thermal-cycling method for disaggregating monoclonal antibody oligomers.

    Science.gov (United States)

    Sadavarte, Rahul H; Ghosh, Raja

    2014-03-01

    Non-native oligomeric forms of biopharmaceutical proteins are therapeutically inactive, and potentially toxic and immunogenic, and therefore undesirable in pharmaceutical formulations. Immunoglobulin G class of antibodies are known to form stable nonnative oligomers through Fab-Fab interactions. In this paper, we investigate thermal-cycling as a technique for disaggregating antibody oligomers. Aggregate containing monoclonal antibody (mAb) samples were exposed to rapid heating and cooling cycles in a thermal-cycler. The heating phase of the thermal-cycle resulted in partial unfolding of the Fab domain, leading to the release of monomer from the oligomer complexes, whereas the rapid cooling that followed led to refolding and minimized the probability of protein reaggregation. The extent of mAb oligomer disaggregation was determined by size-exclusion chromatography and hydrophobic interaction membrane chromatography, whereas protein refolding was assessed by circular dichroism spectroscopy. The thermal-cycling technique in addition to being suitable for disaggregating protein oligomer samples could also potentially be useful for studying the mechanisms of protein aggregation and disaggregation. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  12. BOXTO as a real-time thermal cycling reporter dye

    Indian Academy of Sciences (India)

    PRAKASH

    BOXTO as a real-time thermal cycling reporter dye. ASHRAF I AHMAD. Department of Chemical and Biological Engineering-Molecular Biotechnology, Chalmers University of Technology,. 405 30 Göteborg, Sweden. (Fax, 46 31 773 3910; Email, ashraf.ahmad@molbiotech.chalmers.se). The unsymmetrical cyanine dyes ...

  13. High-speed thermal cycling system and method of use

    Science.gov (United States)

    Hansen, A.D.A.; Jaklevic, J.M.

    1996-04-16

    A thermal cycling system and method of use are described. The thermal cycling system is based on the circulation of temperature-controlled water directly to the underside of thin-walled polycarbonate plates. The water flow is selected from a manifold fed by pumps from heated reservoirs. The plate wells are loaded with typically 15-20 microliters of reagent mix for the PCR process. Heat transfer through the thin polycarbonate is sufficiently rapid that the contents reach thermal equilibrium with the water in less than 15 seconds. Complete PCR amplification runs of 40 three-step cycles have been performed in as little as 14.5 minutes, with the results showing substantially enhanced specificity compared to conventional technology requiring run times in excess of 100 minutes. The plate clamping station is designed to be amenable to robotic loading and unloading of the system. It includes a heated lid, thus eliminating the need for mineral oil overlay of the reactants. The present system includes three or more plate holder stations, fed from common reservoirs but operating with independent switching cycles. The system can be modularly expanded. 13 figs.

  14. Thermal cycling tests on surface-mount assemblies

    Science.gov (United States)

    Jennings, C. W.

    1988-03-01

    The capability of surface-mount (SM) solder joints to withstand various thermal cycle stresses was evaluated through electrical circuit resistance changes of a test pattern and by visual examination for cracks in the solder after exposure to thermal cycling. The joints connected different electrical components, primarily leadless-chip carriers (LCCs), and printed wiring-board (PWB) pads on different laminate substrates. Laminate compositions were epoxy-glass and polyimide-glass with and without copper/Invar/copper (CIC) inner layers, polyimide-quartz, epoxy-Kevlar, and polyimide-Kevlar. The most resistant joints were between small LCCs (24 and 48 pins) and polyimide-glass laminate with CIC inner layers. Processing in joint formation was found to be an important part of joint resistant. Thermal cycling was varied with respect to both time and temperature. A few resistors, capacitors, and inductors showed opens after 500 30-min cycles between -65 C and 125 C. Appreciable moisture contents were measured for laminate materials, especially those of polyimide-Kevlar after equilibration in 100 percent relative humidity at room temperature. If not removed or reduced, moisture can cause delamination in vapor-phase soldering.

  15. Thermal cycling tests on surface-mount assemblies

    Energy Technology Data Exchange (ETDEWEB)

    Jennings, C.W.

    1988-03-01

    The capability of surface-mount (SM) solder joints to withstand various thermal cycle stresses was evaluated through electrical circuit resistance changes of a test pattern and by visual examination for cracks in the solder after exposure to thermal cycling. The joints connected different electrical components, primarily leadless-chip carriers (LCCs), and printed wiring-board (PWB) pads on different laminate substrates. Laminate compositions were epoxy-glass and polyimide-glass with and without copper/Invar/copper (CIC) inner layers, polyimide-quartz, epoxy-Kevlar, and polyimide-Kevlar. The most resistant joints were between small LCCs (24 and 48 pins) and polyimide-glass laminate with CIC inner layers. Processing in joint formation was found to be an important part of joint resistant. Thermal cycling was varied with respect to both time and temperature. A few resistors, capacitors, and inductors showed opens after 500 30-min cycles between -65/degree/C and 125/degree/C. Appreciable moisture contents were measured for laminate materials, especially those of polyimide-Kevlar after equilibration in 100/percent/ relative humidity at room temperature. If not removed or reduced, moisture can cause delamination in vapor-phase soldering. 17 refs, 12 figs.,10 tabs.

  16. Performance characteristics of a quantum Diesel refrigeration cycle

    Energy Technology Data Exchange (ETDEWEB)

    He Jizhou [Department of Physics, Nanchang University, Nanchang 330031 (China)], E-mail: hjzhou@ncu.edu.cn; Wang Hao; Liu Sanqiu [Department of Physics, Nanchang University, Nanchang 330031 (China)

    2009-04-15

    The Diesel refrigeration cycle using an ideal quantum gas as the working substance is called quantum Diesel refrigeration cycle, which is different from Carnot, Ericsson, Brayton, Otto and Stirling refrigeration cycles. For ideal quantum gases, a corrected equation of state, which considers the quantum behavior of gas particles, is used instead of the classical one. The purpose of this paper is to investigate the effect of quantum gas as the working substance on the performance of a quantum Diesel refrigeration cycle. It is found that coefficients of performance of the cycle are not affected by the quantum degeneracy of the working substance, which is the same as that of the classical Diesel refrigeration cycle. However, the refrigeration load is different from those of the classical Diesel refrigeration cycle. Lastly, the influence of the quantum degeneracy on the performance characteristics of the quantum Diesel refrigeration cycle operated in different temperature regions is discussed.

  17. Performance characteristics of a quantum Diesel refrigeration cycle

    Energy Technology Data Exchange (ETDEWEB)

    He, Jizhou; Wang, Hao; Liu, Sanqiu [Department of Physics, Nanchang University, Nanchang 330031 (China)

    2009-04-15

    The Diesel refrigeration cycle using an ideal quantum gas as the working substance is called quantum Diesel refrigeration cycle, which is different from Carnot, Ericsson, Brayton, Otto and Stirling refrigeration cycles. For ideal quantum gases, a corrected equation of state, which considers the quantum behavior of gas particles, is used instead of the classical one. The purpose of this paper is to investigate the effect of quantum gas as the working substance on the performance of a quantum Diesel refrigeration cycle. It is found that coefficients of performance of the cycle are not affected by the quantum degeneracy of the working substance, which is the same as that of the classical Diesel refrigeration cycle. However, the refrigeration load is different from those of the classical Diesel refrigeration cycle. Lastly, the influence of the quantum degeneracy on the performance characteristics of the quantum Diesel refrigeration cycle operated in different temperature regions is discussed. (author)

  18. Transport properties of MnTe films with cracks produced in thermal cycling process

    Science.gov (United States)

    Yang, Liang; Wang, Zhenhua; Zhang, Zhidong

    2017-10-01

    As a promising material in antiferromagnetic spintronics, MnTe films manifested complex characteristics according to previous reports. In this work, we investigate in details the temperature dependence of resistivity of MnTe films grown on SiO2/Si substrate and focus on the divaricating of cooling and warming resistivity-temperature (R-T) curves. It is found that such a divaricating in resistivity is associated with cracks produced in thermal cycles. By comparing the crystalline character and the morphology before and after the cycles, we verify the appearance of cracks and the release of stress in the films. Based on the temperature dependence of thermal-expansion coefficient of Si and MnTe, the origin of the cracks is the mismatched thermal-expansion coefficient ( α). The humps, which only appear in the R-T curve of the first cooling process, are attributed to the produced cracks and/or the unreleased stress.

  19. Transport properties of MnTe films with cracks produced in thermal cycling process

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Liang; Wang, Zhenhua; Zhang, Zhidong [Institute of Metal Research, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shenyang National Laboratory for Materials Science, Shenyang (China)

    2017-10-15

    As a promising material in antiferromagnetic spintronics, MnTe films manifested complex characteristics according to previous reports. In this work, we investigate in details the temperature dependence of resistivity of MnTe films grown on SiO{sub 2}/Si substrate and focus on the divaricating of cooling and warming resistivity-temperature (R-T) curves. It is found that such a divaricating in resistivity is associated with cracks produced in thermal cycles. By comparing the crystalline character and the morphology before and after the cycles, we verify the appearance of cracks and the release of stress in the films. Based on the temperature dependence of thermal-expansion coefficient of Si and MnTe, the origin of the cracks is the mismatched thermal-expansion coefficient (α). The humps, which only appear in the R-T curve of the first cooling process, are attributed to the produced cracks and/or the unreleased stress. (orig.)

  20. Geomagnetism during solar cycle 23: Characteristics

    Directory of Open Access Journals (Sweden)

    Jean-Louis Zerbo

    2013-05-01

    Full Text Available On the basis of more than 48 years of morphological analysis of yearly and monthly values of the sunspot number, the aa index, the solar wind speed and interplanetary magnetic field, we point out the particularities of geomagnetic activity during the period 1996–2009. We especially investigate the last cycle 23 and the long minimum which followed it. During this period, the lowest values of the yearly averaged IMF (3 nT and yearly averaged solar wind speed (364 km/s are recorded in 1996, and 2009 respectively. The year 2003 shows itself particular by recording the highest value of the averaged solar wind (568 km/s, associated to the highest value of the yearly averaged aa index (37 nT. We also find that observations during the year 2003 seem to be related to several coronal holes which are known to generate high-speed wind stream. From the long time (more than one century study of solar variability, the present period is similar to the beginning of twentieth century. We especially present the morphological features of solar cycle 23 which is followed by a deep solar minimum.

  1. Mir Cooperative Solar Array Project Accelerated Life Thermal Cycling Test

    Science.gov (United States)

    Hoffman, David J.; Scheiman, David A.

    1996-01-01

    The Mir Cooperative Solar Array (MCSA) project was a joint U.S./Russian effort to build a photovoltaic (PV) solar array and deliver it to the Russian space station Mir. The MCSA will be used to increase the electrical power on Mir and provide PV array performance data in support of Phase 1 of the International Space Station. The MCSA was brought to Mir by space shuttle Atlantis in November 1995. This report describes an accelerated thermal life cycle test which was performed on two samples of the MCSA. In eight months time, two MCSA solar array 'mini' panel test articles were simultaneously put through 24,000 thermal cycles. There was no significant degradation in the structural integrity of the test articles and no electrical degradation, not including one cell damaged early and removed from consideration. The nature of the performance degradation caused by this one cell is briefly discussed. As a result of this test, changes were made to improve some aspects of the solar cell coupon-to-support frame interface on the flight unit. It was concluded from the results that the integration of the U.S. solar cell modules with the Russian support structure would be able to withstand at least 24,000 thermal cycles (4 years on-orbit). This was considered a successful development test.

  2. Testing of High Thermal Cycling Stability of Low Strength Concrete as a Thermal Energy Storage Material

    Directory of Open Access Journals (Sweden)

    Chao Wu

    2016-09-01

    Full Text Available Concrete has the potential to become a solution for thermal energy storage (TES integrated in concentrating solar power (CSP systems due to its good thermal and mechanical properties and low cost of material. In this study, a low strength concrete (C20 is tested at high temperatures up to 600 °C. Specimens are thermally cycled at temperatures in the range of 400–300 °C, 500–300 °C, and 600–300 °C, which TES can reach in operation. For comparison, specimens also cycled at temperature in the range of 400–25 °C (room temperature, 500–25 °C, and 600–25 °C. It is found from the test results that cracks are not observed on the surfaces of concrete specimens until the temperature is elevated up to 500 °C. There is mechanical deterioration of concrete after exposure to high temperature, especially to high thermal cycles. The residual compressive strength of concrete after 10 thermal cycles between 600 °C and 300 °C is about 58.3%, but the specimens remain stable without spalling, indicating possible use of low strength concrete as a TES material.

  3. Simulation and parametric optimisation of thermal power plant cycles

    Directory of Open Access Journals (Sweden)

    P. Ravindra Kumar

    2016-09-01

    Full Text Available The objective of the paper is to analyse parametric studies and optimum steam extraction pressures of three different (subcritical, supercritical and ultra-supercritical coal fired power plant cycles at a particular main steam temperature of 600 °C by keeping the reheat temperature at 537 °C and condenser pressure at 0.09 bar as constant. In order to maximize the heat rate gain possible with supercritical and ultra-supercritical steam conditions, eight stages of feed water heater arrangement with single reheater is considered. The system is optimized in such a way that the percentage exergetic losses are reduced for the increase of the exergetic efficiency and higher fuel utilization. The plant cycles are simulated and optimized by using Cycle Tempo 5.0 simulation software tool. From the simulation study, it is observed that the thermal efficiency of the three different power plant cycles obtained as 41.40, 42.48 and 43.03%, respectively. The specific coal consumption for three different power plant cycles are 0.56, 0.55 and 0.54 Tonnes/MWh. The improvement in feed water temperatures at the inlet of steam generator of respective cycles are 291, 305 and 316 °C.

  4. Zero cycles on certain surfaces in arbitrary characteristic

    Indian Academy of Sciences (India)

    Let be a field of arbitrary characteristic. Let be a singular surface defined over with multiple rational curve singularities and suppose that the Chow group of zero cycles of its normalisation S ¯ is finite dimensional. We give numerical conditions under which the Chow group of zero cycles of is finite dimensional.

  5. Analysing the thermal characteristics of LAMP joining

    Directory of Open Access Journals (Sweden)

    Tamás Markovits

    2014-07-01

    Full Text Available The increasing utilisation of different material groups (plastic, metal, ceramics in our advanced construction provides many benefits, but the fastening process is a challenge. LAMP (Laser assisted metal plastic joining is a new technique in fastening technology. It means an alternative process from the existing techniques like using adhesives, screwing, riveting etc. The authors have been dealing with this technology for years. In this research work some important thermal phenomena were analysed in order to understand the process of joining more thoroughly. The temperature of the steel partner was measured in case of different laser settings and experimental situations with two measuring techniques: thermocouple and infrared camera. The results show the effect of different influencing factors during heating and the applicability of different measuring methods. The received temperature values can be compared to the characteristic temperature of PMMA polymer (decomposition temperature in order to determine the root cause of bubble forming in the polymer material. From the result the differences between the different applied laser pulse mode for the heating was also determined and it was possible to measure the heating rate during the laser process.

  6. Optimizing the Environmental Performance of In Situ Thermal Remediation Technologies Using Life Cycle Assessment

    DEFF Research Database (Denmark)

    Lemming, Gitte; Nielsen, Steffen G.; Weber, Klaus

    2013-01-01

    in situ thermal remediation technologies (steam enhanced extraction, thermal conduction heating, electrical resistance heating, and radio frequency heating) in order to (1) compare the life-cycle environmental impacts and resource consumption associated with each thermal technology, and (2) identify...

  7. Solar panel thermal cycling testing by solar simulation and infrared radiation methods

    Science.gov (United States)

    Nuss, H. E.

    1980-01-01

    For the solar panels of the European Space Agency (ESA) satellites OTS/MAROTS and ECS/MARECS the thermal cycling tests were performed by using solar simulation methods. The performance data of two different solar simulators used and the thermal test results are described. The solar simulation thermal cycling tests for the ECS/MARECS solar panels were carried out with the aid of a rotatable multipanel test rig by which simultaneous testing of three solar panels was possible. As an alternative thermal test method, the capability of an infrared radiation method was studied and infrared simulation tests for the ultralight panel and the INTELSAT 5 solar panels were performed. The setup and the characteristics of the infrared radiation unit using a quartz lamp array of approx. 15 sq and LN2-cooled shutter and the thermal test results are presented. The irradiation uniformity, the solar panel temperature distribution, temperature changing rates for both test methods are compared. Results indicate the infrared simulation is an effective solar panel thermal testing method.

  8. Thermal Cycling of Mir Cooperative Solar Array (MCSA) Test Panels

    Science.gov (United States)

    Hoffman, David J.; Scheiman, David A.

    1997-01-01

    The Mir Cooperative Solar Array (MCSA) project was a joint US/Russian effort to build a photovoltaic (PV) solar array and deliver it to the Russian space station Mir. The MCSA is currently being used to increase the electrical power on Mir and provide PV array performance data in support of Phase 1 of the International Space Station (ISS), which will use arrays based on the same solar cells used in the MCSA. The US supplied the photovoltaic power modules (PPMs) and provided technical and programmatic oversight while Russia provided the array support structures and deployment mechanism and built and tested the array. In order to ensure that there would be no problems with the interface between US and Russian hardware, an accelerated thermal life cycle test was performed at NASA Lewis Research Center on two representative samples of the MCSA. Over an eight-month period (August 1994 - March 1995), two 15-cell MCSA solar array 'mini' panel test articles were simultaneously put through 24,000 thermal cycles (+80 C to -100 C), equivalent to four years on-orbit. The test objectives, facility, procedure and results are described in this paper. Post-test inspection and evaluation revealed no significant degradation in the structural integrity of the test articles and no electrical degradation, not including one cell damaged early as an artifact of the test and removed from consideration. The interesting nature of the performance degradation caused by this one cell, which only occurred at elevated temperatures, is discussed. As a result of this test, changes were made to improve some aspects of the solar cell coupon-to-support frame interface on the flight unit. It was concluded from the results that the integration of the US solar cell modules with the Russian support structure would be able to withstand at least 24,000 thermal cycles (4 years on-orbit).

  9. Thermal imaging cameras characteristics and performance

    CERN Document Server

    Williams, Thomas

    2009-01-01

    The ability to see through smoke and mist and the ability to use the variances in temperature to differentiate between targets and their backgrounds are invaluable in military applications and have become major motivators for the further development of thermal imagers. As the potential of thermal imaging is more clearly understood and the cost decreases, the number of industrial and civil applications being exploited is growing quickly. In order to evaluate the suitability of particular thermal imaging cameras for particular applications, it is important to have the means to specify and measur

  10. Failure Mechanisms of SAC/Fe-Ni Solder Joints During Thermal Cycling

    Science.gov (United States)

    Gao, Li-Yin; Liu, Zhi-Quan; Li, Cai-Fu

    2017-08-01

    Thermal cycling tests have been conducted on Sn-Ag-Cu/Fe- xNi ( x = 73 wt.% or 45 wt.%) and Sn-Ag-Cu/Cu solder joints according to the Joint Electron Device Engineering Council industrial standard to study their interfacial reliability under thermal stress. The interfacial intermetallic compounds formed for solder joints on Cu, Fe-73Ni, and Fe-45Ni were 4.5 μm, 1.7 μm, and 1.4 μm thick, respectively, after 3000 cycles, demonstrating excellent diffusion barrier effect of Fe-Ni under bump metallization (UBM). Also, two deformation modes, viz. solder extrusion and fatigue crack formation, were observed by scanning electron microscopy and three-dimensional x-ray microscopy. Solder extrusion dominated for solder joints on Cu, while fatigue cracks dominated for solder joints on Fe-45Ni and both modes were detected for those on Fe-73Ni. Solder joints on Fe-Ni presented inferior reliability during thermal cycling compared with those on Cu, with characteristic lifetime of 3441 h, 3190 h, and 1247 h for Cu, Fe-73Ni, and Fe-45Ni UBM, respectively. This degradation of the interfacial reliability for solder joints on Fe-Ni is attributed to the mismatch in coefficient of thermal expansion (CTE) at interconnection level. The CTE mismatch at microstructure level was also analyzed by electron backscatter diffraction for clearer identification of recrystallization-related deformation mechanisms.

  11. Thermal energy storage for low grade heat in the organic Rankine cycle

    Science.gov (United States)

    Soda, Michael John

    addition of graphite to augment heat transfer rates was also tested. Melting and solidification temperatures largely matched predictions. The magnesium salts were found to be less stable under thermal cycling than the waxes. Graphite was only soluble in the waxes. Mixtures of magnesium salts and waxes yielded a layered composite with the less dense waxes creating a sealing layer over the salt layer that significantly increased the stability of the magnesium salts. Research into optimum heat exchangers and storage vessels for these applications indicates that horizontally oriented aluminum pipes with vertically oriented aluminum fins would be the best method of storing and retrieving energy. Fin spacing can be predicted by an equation based on target temperatures and PCM characteristics.

  12. Friction welding thermal and metallurgical characteristics

    CERN Document Server

    Yilbas, Bekir Sami

    2014-01-01

    This book provides insight into the thermal analysis of friction welding incorporating welding parameters such as external, duration, breaking load, and material properties. The morphological and metallurgical changes associated with the resulting weld sites are analysed using characterization methods such as electron scanning microscope, energy dispersive spectroscopy, X-ray Diffraction, and Nuclear reaction analysis.

  13. Micro-/nanoscaled irreversible Otto engine cycle with friction loss and boundary effects and its performance characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Nie, Wenjie; Zhang, ChunQiang [School of Computer, Jiangxi University of Traditional Chinese Medicine, Nanchang 330004 (China); Liao, Qinghong [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); He, Jizhou [Department of Physics, Nanchang University, Nanchang 330047 (China)

    2010-12-15

    An irreversible cycle model of the micro-/nanoscaled Otto engine cycle with internal friction loss is established. The general expressions of the work output and efficiency of the cycle are calculated based on the finite system thermodynamic theory, in which the quantum boundary effect of gas particles as working substance and the mechanical Casimir effect of gas system are considered. It is found that, for a micro-/nanoscaled Otto cycle devices, the work output W and efficiency {eta} of the cycle can be expressed as the functions of the temperature ratio {tau} of the two heat reservoirs, the volume ratio r{sub V} and the surface area ratio r{sub A} of the two isochoric processes, the dimensionless thermal wavelength {lambda} and other parameters of cycle, while for a macroscaled Otto cycle devices, the work output W{sub 0} and efficiency {eta}{sub 0} of the cycle are independent of the surface area ratio r{sub A} and the dimensionless thermal wavelength {lambda}. Further, the influence of boundary of cycle on the performance characteristics of the micro-/nanoscaled Otto cycle are analyzed in detail by introducing the output ratio W/W{sub 0} and efficiency ratio {eta}/{eta}{sub 0}. The results present the general performance characteristics of a micro-/nanoscaled Otto cycle and may serve as the basis for the design of a realistic Otto cycle device in micro-/nanoscale. (author)

  14. Characteristics of local groundwater recharge cycles in South ...

    African Journals Online (AJOL)

    Rainfall events in semi-arid regions of South Africa are characteristically erratic in terms of depths and recurrence rates. Chemical assessment of cyclic rainwater has recognised 3 intervals, spaced over the hydrological cycle, reporting diverse hydrochemical compositions of rainwater in winter and summer rainfall regions.

  15. New method for calculation of integral characteristics of thermal plumes

    DEFF Research Database (Denmark)

    2008-01-01

    A method for calculation of integral characteristics of thermal plumes is proposed. The method allows for determination of the integral parameters of plumes based on speed measurements performed with omnidirectional low velocity thermoanemometers. The method includes a procedure for calculation...... occupant. The improvement in calculation of the characteristics of the thermal plume achieved with the developed method, in comparison with methods used and reported in the literature, is demonstrated....

  16. Plant Characteristics of an Integrated Solid Oxide Fuel Cell Cycle and a Steam Cycle

    DEFF Research Database (Denmark)

    Rokni, Masoud

    2010-01-01

    Plant characteristics of a system containing a solid oxide fuel cell (SOFC) cycle on the top of a Rankine cycle were investigated. Natural gas (NG) was used as the fuel for the plant. A desulfurization reactor removes the sulfur content in the fuel, while a pre-reformer broke down the heavier...... recovery steam generator (HRSG). The remaining energy of the off-gases was recycled back to the topping cycle for further utilization. Several parameter studies were carried out to investigate the sensitivity of the suggested plant. It was shown that the operation temperature of the desulfurization unit...

  17. General performance characteristics of an irreversible ferromagnetic Stirling refrigeration cycle

    Science.gov (United States)

    Lin, G.; Tegus, O.; Zhang, L.; Brück, E.

    2004-02-01

    A new magnetic-refrigeration-cycle model using ferromagnetic materials as a cyclic working substance is set up, in which finite-rate heat transfer, heat leak and regeneration time are taken into account. On the basis of the thermodynamic properties of a ferromagnetic material, the general performance characteristics of the ferromagnetic Stirling refrigeration cycle are investigated and the effects of some key irreversibilities on the performance of the cycle are revealed. By using the optimal-control theory, the optimal relation between the coefficient of performance and the cooling rate is derived and some important performance bounds, e.g., the maximum cooling rate, the maximum coefficient of performance, are determined. Moreover, the optimal operating regions for cooling rate, coefficient of performance and the optimal operating temperatures of a cyclic working substance in the two heat-transfer processes are obtained. Furthermore, the influences of magnetization and magnetic field on the performance characteristics of the cycle are discussed. The results obtained here have general significance and can be deduced to the related ones of the Stirling refrigeration cycle using paramagnetic salt as a cyclic working substance.

  18. Experimental modeling of weld thermal cycle of the heat affected zone (HAZ

    Directory of Open Access Journals (Sweden)

    J. Kulhánek

    2016-10-01

    Full Text Available Contribution deals with experimental modeling of quick thermal cycles of metal specimens. In the introduction of contribution will be presented measured graphs of thermal cycle of heat affected zone (HAZ of weld. Next will be presented experimental simulation of measured thermal cycle on the standard specimens, useable for material testing. This approach makes possible to create material structures of heat affected zone of weld, big enough for standard material testing.

  19. Effect of Material Composition and Environmental Condition on Thermal Characteristics of Conductive Asphalt Concrete.

    Science.gov (United States)

    Pan, Pan; Wu, Shaopeng; Hu, Xiaodi; Liu, Gang; Li, Bo

    2017-02-23

    Conductive asphalt concrete with high thermal conductivity has been proposed to improve the solar energy collection and snow melting efficiencies of asphalt solar collector (ASC). This paper aims to provide some insight into choosing the basic materials for preparation of conductive asphalt concrete, as well as determining the evolution of thermal characteristics affected by environmental factors. The thermal properties of conductive asphalt concrete were studied by the Thermal Constants Analyzer. Experimental results showed that aggregate and conductive filler have a significant effect on the thermal properties of asphalt concrete, while the effect of asphalt binder was not evident due to its low proportion. Utilization of mineral aggregate and conductive filler with higher thermal conductivity is an efficient method to prepare conductive asphalt concrete. Moreover, change in thermal properties of asphalt concrete under different temperature and moisture conditions should be taken into account to determine the actual thermal properties of asphalt concrete. There was no noticeable difference in thermal properties of asphalt concrete before and after aging. Furthermore, freezing-thawing cycles strongly affect the thermal properties of conductive asphalt concrete, due to volume expansion and bonding degradation.

  20. Effect of Material Composition and Environmental Condition on Thermal Characteristics of Conductive Asphalt Concrete

    Directory of Open Access Journals (Sweden)

    Pan Pan

    2017-02-01

    Full Text Available Conductive asphalt concrete with high thermal conductivity has been proposed to improve the solar energy collection and snow melting efficiencies of asphalt solar collector (ASC. This paper aims to provide some insight into choosing the basic materials for preparation of conductive asphalt concrete, as well as determining the evolution of thermal characteristics affected by environmental factors. The thermal properties of conductive asphalt concrete were studied by the Thermal Constants Analyzer. Experimental results showed that aggregate and conductive filler have a significant effect on the thermal properties of asphalt concrete, while the effect of asphalt binder was not evident due to its low proportion. Utilization of mineral aggregate and conductive filler with higher thermal conductivity is an efficient method to prepare conductive asphalt concrete. Moreover, change in thermal properties of asphalt concrete under different temperature and moisture conditions should be taken into account to determine the actual thermal properties of asphalt concrete. There was no noticeable difference in thermal properties of asphalt concrete before and after aging. Furthermore, freezing–thawing cycles strongly affect the thermal properties of conductive asphalt concrete, due to volume expansion and bonding degradation.

  1. Physicochemical Characteristics of Black Garlic after Different Thermal Processing Steps.

    Science.gov (United States)

    Kang, Ok-Ju

    2016-12-01

    This study investigated the physicochemical characteristics of black garlic (BG) after different thermal processing steps. Compared with fresh garlic (FG), the moisture content and pH in BG decreased significantly, while the ash content and browning intensity increased during thermal processing. The total mineral and the free sugar contents were significantly higher than that of the BG2 and BG4 samples, respectively. The free sugar content increased by 16-fold in the BG cloves compared with that of FG, while the amino acid content increased during the first stage of thermal processing, and subsequently decreased. The thiosulfinate content in all samples decreased to during thermal processing. The pyruvic acid content initially increased and then decreased during thermal processing. These results contribute to our understanding of the role of thermal processing in the quality formation of BG.

  2. Measuring Thermal Characteristics of Urban Landscapes

    Science.gov (United States)

    Luvall, Jeffrey C.; Quattrochi, Dale A.; Rickman, Doug L.

    1999-01-01

    The additional heating of the air over the city is the result of the replacement of naturally vegetated surfaces with those composed of asphalt, concrete, rooftops and other man-made materials. The temperatures of these artificial surfaces can be 20 to 40 C higher than vegetated surfaces. Materials such as asphalt store much of the sun's energy and remains hot long after sunset. This produces a dome of elevated air temperatures 5 to 8 C greater over the city, compared to the air temperatures over adjacent rural areas. This effect is called the "urban heat island". Urban landscapes are a complex mixture of vegetated and nonvegetated surfaces. It is difficult to take enough temperature measurements over a large city area to characterize the complexity of urban radiant surface temperature variability. However, the use of remotely sensed thermal data from airborne scanners are ideal for the task. In a study funded by NASA, a series of flights over Huntsville, Alabama were performed in September 1994 and over Atlanta, Georgia in May 1997. Analysis of thermal energy responses for specific or discrete surfaces typical of the urban landscape (e.g., asphalt, building rooftops, vegetation) requires measurements at a very fine spatial scale (i.e., urban forest in both mitigating the urban heat island effect, in making cities more aesthetically pleasing and more habitable environments, and in overall cooling of the community. In this presentation we will examine the techniques of analyzing remotely sensed data for measuring the effect of various urban surfaces on their contribution to the urban heat island effect.

  3. Effect of multiple extrusions and influence of PP contamination on the\\ud thermal characteristics of bottle grade recycled PET

    OpenAIRE

    Itim, Bachir; Philip, Mathew

    2015-01-01

    The thermal characteristics of bottle grade recycled PET pellets contaminated with 5% PP prepared by multiple extrusions were studied by differential scanning calorimetry (DSC) at constant heating rate of 10 degrees C/min for various extrusion cycles. The peak temperature of crystallization Tc, the enthalpy of crystallization dHc and the degree of crystallinity Xc were found to be dependent on the number of extrusion cycles. From the dependence on extrusion cycles, the analysis of the crystal...

  4. Combustion characteristics of thermally stressed hydrocarbon fuels

    Science.gov (United States)

    Curtis, Colin William

    Liquid propelled propulsion systems, which range from rocket systems to hypersonic scramjet and ramjet engines, require active cooling in order to prevent additional payload requirements. In these systems, the liquid fuel is used as a coolant and is delivered through micro-channels that surround the combustion chambers, nozzles, as well as the exterior surfaces in order to extract heat from these affected areas. During this process, heat exchange occurs through phase change, sensible heat extraction, and endothermic reactions experienced by the liquid fuel. Previous research has demonstrated the significant modifications in fuel composition and changes to the fuel's physical properties that can result from these endothermic reactions. As a next step, we are experimentally investigating the effect that endothermic reactions have on fundamental flame behavior for real hydrocarbon fuels that are used as rocket and jet propellants. To achieve this goal, we have developed a counter-flow flame burner to measure extinction limits of the thermally stressed fuels. The counter-flow flame system is to be coupled with a high pressure reactor, capable of subjecting the fuel to 170 atm and 873 K, effectively simulating the extreme environment that cause the liquid fuel to experience endothermic reactions. The fundamental flame properties of the reacted fuels will be compared to those of unreacted fuels, allowing us to determine the role of endothermic reactions on the combustion behavior of current hydrocarbon jet and rocket propellants. To quantify the change in transport properties and chemical kinetics of the reacting mixture, simultaneous numerical simulations of the reactor portion of the experiment coupled with a counterflow flame simulation are performed using n-heptane and n-dodecane.

  5. Geosynthetic clay liners shrinkage under simulated daily thermal cycles.

    Science.gov (United States)

    Sarabadani, Hamid; Rayhani, Mohammad T

    2014-06-01

    Geosynthetic clay liners are used as part of composite liner systems in municipal solid waste landfills and other applications to restrict the escape of contaminants into the surrounding environment. This is attainable provided that the geosynthetic clay liner panels continuously cover the subsoil. Previous case histories, however, have shown that some geosynthetic clay liner panels are prone to significant shrinkage and separation when an overlying geomembrane is exposed to solar radiation. Experimental models were initiated to evaluate the potential shrinkage of different geosynthetic clay liner products placed over sand and clay subsoils, subjected to simulated daily thermal cycles (60°C for 8 hours and 22°C for 16 hours) modelling field conditions in which the liner is exposed to solar radiation. The variation of geosynthetic clay liner shrinkage was evaluated at specified times by a photogrammetry technique. The manufacturing techniques, the initial moisture content, and the aspect ratio (ratio of length to width) of the geosynthetic clay liner were found to considerably affect the shrinkage of geosynthetic clay liners. The particle size distribution of the subsoil and the associated suction at the geosynthetic clay liner-subsoil interface was also found to have significant effects on the shrinkage of the geosynthetic clay liner. © The Author(s) 2014.

  6. How Thermal Fatigue Cycles Change the Rheological Behavior of Polymer Modified Bitumen?

    NARCIS (Netherlands)

    Glaoui, B.; Merbouh, M.; Van de Ven, M.F.C.; Chailleux, E.; Youcefi, A.

    2013-01-01

    The paper deals with the problem of thermal fatigue cycles phenomenon, which affects the performance of flexible pavement. The purpose of the paper is to extent the knowledge on the rheology of polymer modified bitumen which was affected by cycles of thermal fatigue. The aim of this research is to

  7. Adverse childhood event experiences, fertility difficulties and menstrual cycle characteristics.

    Science.gov (United States)

    Jacobs, Marni B; Boynton-Jarrett, Renee D; Harville, Emily W

    2015-01-01

    Increased childhood adversity may be affect adult fertility, however, the mechanism through which this occurs is unclear. Menstrual cycle abnormalities are predictive of fertility difficulties, and stress influences menstrual cycle characteristics. Here, we assess whether adverse childhood experiences (ACEs) are associated with fertility difficulties and menstrual cycle dysregulation, offering a plausible mechanism for the link between lifetime stress and fertility. From April 2012 to February 2014, 742 pregnant and non-pregnant women aged 18-45 years residing in southeastern Louisiana provided information on childhood adversity and reproductive history. Associations between ACEs and fertility difficulties and menstrual cycle patterns were evaluated. As the number of ACEs increased, risk of fertility difficulties and amenorrhea increased (RR = 1.09, 95% CI 1.05-1.13 and RR = 1.07, 95% CI 1.04-1.10, respectively), while fecundability decreased [fecundability ratio (FR) = 0.97, 95% CI 0.95-1.00]. Compared to women with no adversity, women in the high adversity group were more likely to experience both infertility and amenorrhea (RR = 2.75, 95% CI 1.45-5.21 and RR = 2.54, 95% CI 1.52-4.25, respectively), and reduced fecundability (FR = 0.75, 95% CI 0.56-1.00). Although similar patterns were seen for menstrual cycle irregularity, associations were diminished. Associations did not materially change following adjustment for age, body mass index, race, education, smoking and income. Results are constrained by the self-report nature of the study and the limited generalizability of the study population. To our knowledge, this is the first study to present evidence of a link between childhood stressors, menstrual cycle disruption and fertility difficulties. The effect of childhood stress on fertility may be mediated through altered functioning of the HPA axis, acting to suppress fertility in response to less than optimal reproductive circumstances.

  8. Rapid thermal cycling of metal-supported solid oxide fuel cellmembranes

    Energy Technology Data Exchange (ETDEWEB)

    Matus, Yuriy B.; De Jonghe, Lutgard C.; Jacobson, Craig P.; Visco, Steven J.

    2004-01-02

    Solid oxide fuel cell (SOFC) membranes were developed in which zirconia-based electrolyte thin films were supported by a composite metal/ceramic electrode, and were subjected to rapid thermal cycling between 200 and 800 C. The effects of this cycling on membrane performance were evaluated. The membranes, not yet optimized for performance, showed a peak power density of 350mW/cm2at 900 C in laboratory-sized SOFCs that was not affected by the thermal cycling. This resistance to cycling degradation is attributed to the close matching of thermal expansion coefficient of the cermet support electrode with that of the zirconia electrolyte.

  9. Modelling and Improvement of Thermal Cycling in Power Electronics for Motor Drive Applications

    DEFF Research Database (Denmark)

    Vernica, Ionut; Ma, Ke; Blaabjerg, Frede

    2016-01-01

    cycling of power devices in a motor drive application and modelling their impact on the thermal stress. The motor drive system together with the thermal cycling in the power semiconductors have been modelled, and after investigating the dynamic behavior of the system, adverse temperature swings......It is well known that the dynamical change of the thermal stress in the power devices is one of the major factors that have influences on the overall efficiency and reliability of power electronics. The main objective of this paper consists of identifying the main parameters that affect the thermal...... are identified during the acceleration and deceleration periods of the motor. The main causes for these adverse thermal cycles have been presented and, consequently, the influence of the deceleration slope, modulation technique and reactive current on the thermal cycles has been analyzed. Finally, the improved...

  10. Interim assessment of the denatured /sup 233/U fuel cycle: feasibility and nonproliferation characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Abbott, L.S.; Bartine, D.E.; Burns, T.J. (eds.)

    1978-12-01

    A fuel cycle that employs /sup 233/U denatured with /sup 238/U and mixed with thorium fertile material is examined with respect to its proliferation-resistance characteristics and its technical and economic feasibility. The rationale for considering the denatured /sup 233/U fuel cycle is presented, and the impact of the denatured fuel on the performance of Light-Water Reactors, Spectral-Shift-Controlled Reactors, Gas-Cooled Reactors, Heavy-Water Reactors, and Fast Breeder Reactors is discussed. The scope of the R, D and D programs to commercialize these reactors and their associated fuel cycles is also summarized and the resource requirements and economics of denatured /sup 233/U cycles are compared to those of the conventional Pu/U cycle. In addition, several nuclear power systems that employ denatured /sup 233/U fuel and are based on the energy center concept are evaluated. Under this concept, dispersed power reactors fueled with denatured or low-enriched uranium fuel are supported by secure energy centers in which sensitive activities of the nuclear cycle are performed. These activities include /sup 233/U production by Pu-fueled transmuters (thermal or fast reactors) and reprocessing. A summary chapter presents the most significant conclusions from the study and recommends areas for future work.

  11. Menstrual cycle characteristics in women with persistent schizophrenia.

    Science.gov (United States)

    Gleeson, Pia C; Worsley, Roisin; Gavrilidis, Emorfia; Nathoo, Shainal; Ng, Elisabeth; Lee, Stuart; Kulkarni, Jayashri

    2016-05-01

    Oestradiol has been implicated in the pathogenesis of schizophrenia. Women with schizophrenia often suffer with menstrual dysfunction, usually associated with low oestradiol levels, but whether menstrual dysfunction has an effect on their psychiatric symptoms is not well researched. The aim of this study is to document the menstrual characteristics of women with chronic schizophrenia with focus upon menstrual regularity, menstrual cycle length and menstrual symptoms. To determine which patient characteristics are associated with irregular menses and whether irregular menses are associated with the severity of psychotic symptoms, menstrual symptoms or depressive symptoms. Cross-sectional analyses using baseline data of women enrolled in a clinical trial. Inclusion criteria include Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition, Text Revision diagnosis of schizophrenia, schizoaffective or schizophreniform disorder; aged between 18 and 51 years; residual symptoms of psychosis despite treatment with a stable dose of antipsychotic medication for at least 4 weeks. Menstrual cycle characteristics including regularity, cycle length and menstrual associated symptoms were documented. Symptoms of schizophrenia were measured using Positive and Negative Syndrome Scale, cognition was measured using Repeatable Battery for the Assessment of Neuropsychological Status and depression was assessed using the Montgomery-Asberg Depression Rating Scale. Blood samples were collected at baseline for hormone assays. Of the 139 women, 77 (55.4%) had regular menses, 57 (41%) had irregular menses and 5 (3.6%) women had missing data on their menstrual cycle. Use of atypical antipsychotics associated with hyperprolactinaemia was positively associated with irregular menses (odds ratio = 4.4, 95% confidence interval = [1.8, 10.9], p = 0.001), while age more than 30 years was negatively associated (odds ratio = 0.3, 95% confidence interval = [0.1, 0.6], p = 0.004). Women with

  12. Laser Soldering and Thermal Cycling Tests of Monolithic Silicon Pixel Chips

    CERN Document Server

    Strand, Frode Sneve

    2015-01-01

    An ALPIDE-1 monolithic silicon pixel sensor prototype has been laser soldered to a flex printed circuit using a novel interconnection technique using lasers. This technique is to be optimised to ensure stable, good quality connections between the sensor chips and the FPCs. To test the long-term stability of the connections, as well as study the effects on hit thresholds and noise in the sensor, it was thermally cycled in a climate chamber 1200 times. The soldered connections showed good qualities like even melting and good adhesion on pad/flex surfaces, and the chip remained in working condition for 1080 cycles. After this, a few connections failed, having cracks in the soldering tin, rendering the chip unusable. Threshold and noise characteristics seemed stable, except for the noise levels of sector 2 in the chip, for 1000 cycles in a temperature interval of "10^{\\circ}" and "50^{\\circ}" C. Still, further testing with wider temperature ranges and more cycles is needed to test the limitations of the chi...

  13. Flexible thermal cycle test equipment for concentrator solar cells

    Science.gov (United States)

    Hebert, Peter H [Glendale, CA; Brandt, Randolph J [Palmdale, CA

    2012-06-19

    A system and method for performing thermal stress testing of photovoltaic solar cells is presented. The system and method allows rapid testing of photovoltaic solar cells under controllable thermal conditions. The system and method presents a means of rapidly applying thermal stresses to one or more photovoltaic solar cells in a consistent and repeatable manner.

  14. Economic optimization of a Kalina cycle for a parabolic trough solar thermal power plant

    DEFF Research Database (Denmark)

    Modi, Anish; Kærn, Martin Ryhl; Andreasen, J. G.

    2015-01-01

    technology for the conversion of solar thermal energy into electricity. In this paper, a Kalina cycle and a steam Rankine cycle are compared in terms of the total capital investment cost for use in a parabolic trough solar thermal power plant without storage. In order to minimize the total capital investment...... cost of the Kalina cycle power plant (the solar field plus the power cycle), an optimization was performed by varying the turbine outlet pressure, the separator inlet temperature and the separator inlet ammonia mass fraction. All the heat exchangers were modelled as shell and tube type using suitable......The Kalina cycle has recently seen increased interest as a replacement for the more traditional steam Rankine cycle for geothermal, solar, ocean thermal energy conversion and waste heat recovery applications. The Kalina cycle uses a mixture of ammonia and water as the working fluid. The ammonia...

  15. Determination of Urban Thermal Characteristics on an Urban/Rural ...

    African Journals Online (AJOL)

    This study explores the potential of multispectral remotely sensed dataset in determining the influence of rural/urban LULC gradient on urban thermal characteristics. A rectangular eleven band Landsat 8 image subset was delineated from the central business district to the rural periphery and classified into most dominant ...

  16. Impact of modified soil thermal characteristic on the simulated ...

    Indian Academy of Sciences (India)

    In the present study, the influence of soil thermal characteristics (STC) on the simulated monsoon climate over south Asia is analyzed. The study was motivated by a common warm temperature bias over the plains of northern India that has been noticed in several global and regional climate models. To address this warm ...

  17. An Assay of some Thermal Characteristics, Chemical and ...

    African Journals Online (AJOL)

    ADOWIE PERE

    JASEM ISSN 1119-8362. All rights reserved. J. Appl. Sci. Environ. Manage. August 2017. Vol. 21 (5) 931-935. Full-text Available Online at www.ajol.infoand www.bioline.org.br/ja. An Assay of some Thermal Characteristics, Chemical and Phytochemical Constituents of Hymenocarida Acida Timber. *. 1. UDEOZO, IP;. 2.

  18. Thermal characteristics of pure and substituted gel grown Gd ...

    Indian Academy of Sciences (India)

    Unknown

    greater detail as IR spectroscopy results suggest water of hydration present in the pure Gd-heptamolybdate only but not the ones substituted by barium. This paper reports the results of thermal characteristics of the pure Gd- heptamolybdate and substituted Gd–Ba-molybdate crys- tals grown by gel encapsulation technique.

  19. [Study on the thermal radiation polarization characteristics of ice].

    Science.gov (United States)

    Wang, Ting-Ting; Zhao, Yun-Sheng; Zhang, Hong-Yan; Zhang, Xia; Zhang, Li-Li

    2014-03-01

    As an important parameter of the global energy balance, climate, hydrological and ecological model, ice directly affects the energy balance of the earth-atmosphere system, weather and climate. It is of great significance to use the thermal infrared polarization technology to study ice thermal radiation. For the ice monitoring and the impact of global climate change on the ice, studies on ice thermal radiation polarization characteristics were conducted based on the wavelength, detection angle and azimuth angle. The results show that the wavelength has an obvious impact on the ice thermal radiation polarization properties. The polarized radiance of four bands shows that L(CH1) > L(CH3) > L(CH4) > L(CH2) while the polarization brightness temperature shows that T(CH4) > T(CH1) > TCH2 > TCH3. It's better to use the brightness temperature of the third channel than the radiance to study the thermal radiation polarization. The detection angle affects the ice thermal radiation polarization characteristics greatly and there are some differences between the polarization angles. The brightness temperature of ice is the lowest in the detection angle of 10 degrees and the polarization angle of 30 degrees, which are non-accidental factors. These was closely related to ice physical and chemical properties. The degree of ice polarization performance shows that P0 thermal radiation polarization characteristics was not significant. And it is affected by the roughness of the surface, organizational structure and other factors which are direct results of ice emitted radiation at different azimuth angles.

  20. The effects of deep water cycling on planetary thermal evolution

    Science.gov (United States)

    Sandu, Constantin; Lenardic, Adrian; McGovern, Patrick

    2011-12-01

    We use a parameterized convection model to investigate the effects of deep water cycling on the thermal evolution of an Earth-like planet. The model incorporates two water reservoirs, a surface and an interior mantle reservoir. Exchange between the two is calculated using a mantle convection parameterization that allows for temperature- and water-dependent mantle viscosity together with internally self-consistent degassing and regassing parameterizations. The balance between degassing and regassing depends on the average spreading rate of tectonic plates, the amount of water partitioned into melt, the thickness of a mantle melt zone, and of a hydrated layer at the top of subducting plates. Degassing scales with melt zone thickness such that an early period of extensive melting would create a drier and more viscous mantle, shifting the solidus line in a direction that would reduce the melt zone thickness and the rate of mantle heat loss. Coupling a hydrated zone thickness-dependent regassing factor to the model, to mimic water delivery to the mantle via a serpentinized layer, allows for the potential of a reversing point where the overall water flow direction switches from degassing to regassing as the mantle cools. The water effect on viscosity creates a negative feedback that tends to regulate the final amount of water in the mantle so it is not strongly dependent on the initial amount of planetary water. The final amount of water in the surface reservoir is then determined by this feedback effect together with the initial water budget of the entire planet. This implies that if the initial water budget of a planet can be estimated, from planetary formation models, then the volume of surface water can be used to estimate the volume of water in the mantle of an Earth-like planet. Applying this methodology to the Earth leads to predictions for water concentration in the Earth's mantle that are in line with geochemical and petrological constraints.

  1. Dynamic thermal characteristics of heat pipe via segmented thermal resistance model for electric vehicle battery cooling

    Science.gov (United States)

    Liu, Feifei; Lan, Fengchong; Chen, Jiqing

    2016-07-01

    Heat pipe cooling for battery thermal management systems (BTMSs) in electric vehicles (EVs) is growing due to its advantages of high cooling efficiency, compact structure and flexible geometry. Considering the transient conduction, phase change and uncertain thermal conditions in a heat pipe, it is challenging to obtain the dynamic thermal characteristics accurately in such complex heat and mass transfer process. In this paper, a ;segmented; thermal resistance model of a heat pipe is proposed based on thermal circuit method. The equivalent conductivities of different segments, viz. the evaporator and condenser of pipe, are used to determine their own thermal parameters and conditions integrated into the thermal model of battery for a complete three-dimensional (3D) computational fluid dynamics (CFD) simulation. The proposed ;segmented; model shows more precise than the ;non-segmented; model by the comparison of simulated and experimental temperature distribution and variation of an ultra-thin micro heat pipe (UMHP) battery pack, and has less calculation error to obtain dynamic thermal behavior for exact thermal design, management and control of heat pipe BTMSs. Using the ;segmented; model, the cooling effect of the UMHP pack with different natural/forced convection and arrangements is predicted, and the results correspond well to the tests.

  2. Degradation of Teflon(trademark) FEP Following Charged Particle Radiation and Rapid Thermal Cycling

    Science.gov (United States)

    Townsend, Jacqueline; Powers, Charles; Viens, Michael; Ayres-Treusdell, Mary; Munoz, Bruno

    1999-01-01

    During the Second Servicing Mission (SM2) of the Hubble Space Telescope (HST) severe degradation was observed on the outer layer of the thermal control blankets. Astronaut observations and photographs revealed large cracks in the metallized Teflon(trademark) FEP (fluorinated ethylene propylene), the outer layer of the multi-layer insulation (MLI), in many locations around the telescope. In an effort to understand what elements of the space environment might cause such damage, pristine Teflon(trademark) FEP was tested for durability to radiation and thermal cycling. Specimens were subjected to electron and proton fluences comparable to those experienced by HST and were subsequently thermal cycled in a custom-built rapid thermal cycle chamber. Tensile tests of the specimens showed that radiation followed by thermal cycling significantly reduced the ultimate strength and elongation of Teflon(trademark) FEP.

  3. Degradation of Teflon(tm) FEP Following Charged Particle Radiation and Rapid Thermal Cycling

    Science.gov (United States)

    Townsend, Jacqueline; Powers, Charles; Viens, Michael; Ayres-Treusdell, Mary; Munoz, Bruno

    1998-01-01

    During the Second Servicing Mission (SM2) of the Hubble Space Telescope (HST) severe degradation was observed on the outer layer of the thermal control blankets. Astronaut observations and photographs revealed large cracks in the metallized Teflon(R) FEP (fluorinated ethylene propylene), the outer layer of the multi-layer insulation (MLI), in many locations around the telescope. In an effort to understand what elements of the space environment might cause such damage, pristine Teflon(R) FEP was tested for durability to radiation and thermal cycling. Specimens were subjected to electron and proton fluences comparable to those experienced by HST and were subsequently thermal cycled in a custom-built rapid thermal cycle chamber. Tensile tests of the specimens showed that radiation followed by thermal cycling significantly reduced the ultimate strength and elongation of Teflon(R) FEP.

  4. Quantifying dynamic characteristics of human walking for comprehensive gait cycle.

    Science.gov (United States)

    Mummolo, Carlotta; Mangialardi, Luigi; Kim, Joo H

    2013-09-01

    Normal human walking typically consists of phases during which the body is statically unbalanced while maintaining dynamic stability. Quantifying the dynamic characteristics of human walking can provide better understanding of gait principles. We introduce a novel quantitative index, the dynamic gait measure (DGM), for comprehensive gait cycle. The DGM quantifies the effects of inertia and the static balance instability in terms of zero-moment point and ground projection of center of mass and incorporates the time-varying foot support region (FSR) and the threshold between static and dynamic walking. Also, a framework of determining the DGM from experimental data is introduced, in which the gait cycle segmentation is further refined. A multisegmental foot model is integrated into a biped system to reconstruct the walking motion from experiments, which demonstrates the time-varying FSR for different subphases. The proof-of-concept results of the DGM from a gait experiment are demonstrated. The DGM results are analyzed along with other established features and indices of normal human walking. The DGM provides a measure of static balance instability of biped walking during each (sub)phase as well as the entire gait cycle. The DGM of normal human walking has the potential to provide some scientific insights in understanding biped walking principles, which can also be useful for their engineering and clinical applications.

  5. Thermal and electronic transport characteristics of highly stretchable graphene kirigami.

    Science.gov (United States)

    Mortazavi, Bohayra; Lherbier, Aurélien; Fan, Zheyong; Harju, Ari; Rabczuk, Timon; Charlier, Jean-Christophe

    2017-10-20

    For centuries, cutting and folding papers with special patterns have been used to build beautiful, flexible and complex three-dimensional structures. Inspired by the old idea of kirigami (paper cutting), and the outstanding properties of graphene, recently graphene kirigami structures were fabricated to enhance the stretchability of graphene. However, the possibility of further tuning the electronic and thermal transport along the 2D kirigami structures has remained original to investigate. We therefore performed extensive atomistic simulations to explore the electronic, heat and load transfer along various graphene kirigami structures. The mechanical response and thermal transport were explored using classical molecular dynamics simulations. We then used a real-space Kubo-Greenwood formalism to investigate the charge transport characteristics in graphene kirigami. Our results reveal that graphene kirigami structures present highly anisotropic thermal and electrical transport. Interestingly, we show the possibility of tuning the thermal conductivity of graphene by four orders of magnitude. Moreover, we discuss the engineering of kirigami patterns to further enhance their stretchability by more than 10 times as compared with pristine graphene. Our study not only provides a general understanding concerning the engineering of electronic, thermal and mechanical response of graphene, but more importantly can also be useful to guide future studies with respect to the synthesis of other 2D material kirigami structures, to reach highly flexible and stretchable nanostructures with finely tunable electronic and thermal properties.

  6. Thermal cycling tests of actively cooled beryllium copper joints

    Energy Technology Data Exchange (ETDEWEB)

    Roedig, M.; Duwe, R.; Linke, J.; Schuster, A.; Wiechers, B. [Forschungszentrum Juelich GmbH (Germany)

    1998-01-01

    Screening tests (steady state heating) and thermal fatigue tests with several kinds of beryllium-copper joints have been performed in an electron beam facility. Joining techniques under investigation were brazing with silver containing and silver-free braze materials, hot isostatic pressing (HIP) and diffusion bonding (hot pressing). Best thermal fatigue performance was found for the brazed samples. (author)

  7. To What Degree Thermal Cycles Affect Chalk Strength

    DEFF Research Database (Denmark)

    Livada, Tijana; Nermoen, Anders; Korsnes, Reidar Inger

    and water saturated chalk. Sixty disks of dry Kansas chalk exposed to different number of temperature cycles were tested for tensile strength using a Brazilian test. Changes in elastic properties as function of number of temperature cycles of the same chalk, but now saturated in water, were studied using...... triaxial cell experiments. For dry rock, no significant effects of temperature cycling was found on average tensile strength, however the range of the tensile failure stress is doubled for the samples exposed to 50 temperature cycles, as opposed to those to none. For water saturated cores, the temperature...

  8. Effect of Thermal Cycling on the Tensile Behavior of CF/AL Fiber Metal Laminates

    Directory of Open Access Journals (Sweden)

    Muhammad Farhan Noor

    2017-09-01

    Full Text Available The objective of this research work was to estimate the effect of thermal cycling on the tensile behavior of CARALL composites. Fiber metal laminates (FMLs, based on 2D woven carbon fabric and 2024-T3 Alclad aluminum alloy sheet, was manufactured by pressure molding technique followed by hand layup method. Before fabrication, aluminum sheets were anodized with phosphoric acid to produce micro porous alumina layer on surface. This micro-porous layer is beneficial to produce strong bonding between metal and fiber surfaces in FMLs. The effect of thermal cycling (-65 to +70ºC on the tensile behavior of Cf/Al based FML was studied. Tensile strength was increased after 10 thermal cycles, but it was slightly decreased to some extent after 30, and 50 thermal cycles. Tensile modulus also shown the similar behavior as that of tensile strength.

  9. Influence of micro-structural parameters and thermal cycling on the ...

    Indian Academy of Sciences (India)

    Keywords. Ultra high performance fibre reinforced cement-based composite; CARDIFRC; micro-structure; mechanical and fracture properties; thermal cycling. ... Author Affiliations. B L Karihaloo1. School of Engineering, Cardiff University, Cardiff, UK ...

  10. Thermal characteristics of mountain desert terrain derived from thermal infrared multispectral scanner measurements

    Science.gov (United States)

    Astling, E. G.; Quattrochi, D. A.

    1989-01-01

    The spatial and temporal variability of mountain-desert territory thermal is examined with an airborne thermal infrared multispectral scanner (TIMS). The purpose of the study is to demonstrate that inhomogeneities of the surface temperatures in the area can be adequately large to influence mesoscale circulations and the turbulence characteristics of boundary-layer flow. Ground truth measurements are compared to the TIMS imagery, with focus placed on the thermal infrared sensitivity to wet and dry soils, terrain elevation, and soil type. The results indicate that variations in the thermal features are dependent on soil type and soil moisture, and that the dependence on surface radiative temperatures on terrain elevation is apparent in daytime measurements.

  11. Relationships between indoor radon concentrations, thermal retrofit and dwelling characteristics.

    Science.gov (United States)

    Collignan, Bernard; Le Ponner, Eline; Mandin, Corinne

    2016-12-01

    A monitoring campaign was conducted on a sample of more than 3400 dwellings in Brittany, France from 2011 to 2014. The measurements were collected using one passive dosimeter per dwelling over two months during the heating season, according to the NF ISO 11665-8 (2013) standard. Moreover, building characteristics such as the period of construction, construction material, type of foundation, and thermal retrofit were determined using a questionnaire. The final data set consisted of 3233 houses with the measurement results and the questionnaire answers. Multivariate linear regression models were applied to explore the relationships between the indoor radon concentrations and building characteristics, particularly the thermal retrofit. The geometric mean of the indoor radon concentration was 155 Bq m(-3) (with a geometric standard deviation of 3). The houses that had undergone a thermal retrofit had a higher average radon concentration than those that had not, which may have been due to a decrease in air permeability of the building envelope following rehabilitation work that did not systematically include proper management of the ventilation. Other building characteristics, primarily the building material and the foundation type, were associated with the indoor radon concentration. The indoor radon concentrations were higher in older houses built with granite or other stone, with a slab-on-grade foundation and without any ventilation system. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. The Effects of Thermal Cycling on Gallium Nitride and Silicon Carbide Semiconductor Devices for Aerospace Use

    Science.gov (United States)

    Patterson, Richard L.; Hammoud, Ahmad

    2012-01-01

    Electronics designed for use in NASA space missions are required to work efficiently and reliably under harsh environment conditions. These Include radiation, extreme temperatures, thermal cycling, to name a few. Preliminary data obtained on new Gallium Nitride and Silicon Carbide power devices under exposure to radiation followed by long term thermal cycling are presented. This work was done in collaboration with GSFC and JPL in support of the NASA Electronic Parts and Packaging (NEPP) Program

  13. Models for optimum thermo-ecological criteria of actual thermal cycles

    Directory of Open Access Journals (Sweden)

    Açikkalp Emin

    2013-01-01

    Full Text Available In this study, the ecological optimization point of irreversible thermal cycles (refrigerator, heat pump and power cycles was investigated. The importance of ecological optimization is to propose a way to use fuels and energy source more efficiently because of an increasing energy need and environmental pollution. It provides this by maximizing obtained (or minimizing supplied work and minimizing entropy generation for irreversible (actual thermal cycles. In this research, ecological optimization was defined for all basic irreversible thermal cycles, by using the first and second laws of thermodynamics. Finally, the ecological optimization was defined in thermodynamic cycles and results were given to show the effects of the cycles’ ecological optimization point, efficiency, COP and power output (or input, and exergy destruction.

  14. Quantum Performance of Thermal Machines over Many Cycles

    Science.gov (United States)

    Watanabe, Gentaro; Venkatesh, B. Prasanna; Talkner, Peter; del Campo, Adolfo

    2017-02-01

    The performance of quantum heat engines is generally based on the analysis of a single cycle. We challenge this approach by showing that the total work performed by a quantum engine need not be proportional to the number of cycles. Furthermore, optimizing the engine over multiple cycles leads to the identification of scenarios with a quantum enhancement. We demonstrate our findings with a quantum Otto engine based on a two-level system as the working substance that supplies power to an external oscillator.

  15. Quantum Performance of Thermal Machines over Many Cycles.

    Science.gov (United States)

    Watanabe, Gentaro; Venkatesh, B Prasanna; Talkner, Peter; Del Campo, Adolfo

    2017-02-03

    The performance of quantum heat engines is generally based on the analysis of a single cycle. We challenge this approach by showing that the total work performed by a quantum engine need not be proportional to the number of cycles. Furthermore, optimizing the engine over multiple cycles leads to the identification of scenarios with a quantum enhancement. We demonstrate our findings with a quantum Otto engine based on a two-level system as the working substance that supplies power to an external oscillator.

  16. Simulating Thermal Cycling and Isothermal Deformation Response of Polycrystalline NiTi

    Science.gov (United States)

    Manchiraju, Sivom; Gaydosh, Darrell J.; Noebe, Ronald D.; Anderson, Peter M.

    2011-01-01

    A microstructure-based FEM model that couples crystal plasticity, crystallographic descriptions of the B2-B19' martensitic phase transformation, and anisotropic elasticity is used to simulate thermal cycling and isothermal deformation in polycrystalline NiTi (49.9at% Ni). The model inputs include anisotropic elastic properties, polycrystalline texture, DSC data, and a subset of isothermal deformation and load-biased thermal cycling data. A key experimental trend is captured.namely, the transformation strain during thermal cycling is predicted to reach a peak with increasing bias stress, due to the onset of plasticity at larger bias stress. Plasticity induces internal stress that affects both thermal cycling and isothermal deformation responses. Affected thermal cycling features include hysteretic width, two-way shape memory effect, and evolution of texture with increasing bias stress. Affected isothermal deformation features include increased hardening during loading and retained martensite after unloading. These trends are not captured by microstructural models that lack plasticity, nor are they all captured in a robust manner by phenomenological approaches. Despite this advance in microstructural modeling, quantitative differences exist, such as underprediction of open loop strain during thermal cycling.

  17. Adsorption characteristics of water vapor on ferroaluminophosphate for desalination cycle

    KAUST Repository

    Kim, Youngdeuk

    2014-07-01

    The adsorption characteristics of microporous ferroaluminophosphate adsorbent (FAM-Z01, Mitsubishi Plastics) are evaluated for possible application in adsorption desalination and cooling (AD) cycles. A particular interest is its water vapor uptake behavior at assorted adsorption temperatures and pressures whilst comparing them to the commercial silica gels of AD plants. The surface characteristics are first carried out using N2 gas adsorption followed by the water vapor uptake analysis for temperature ranging from 20°C to 80°C. We propose a hybrid isotherm model, composing of the Henry and the Sips isotherms, which can be integrated to satisfactorily fit the experimental data of water adsorption on the FAM-Z01. The hybrid model is selected to fit the unusual isotherm shapes, that is, a low adsorption in the initial section and followed by a rapid vapor uptake leading to a likely micropore volume filling by hydrogen bonding and cooperative interaction in micropores. It is shown that the equilibrium adsorption capacity of FAM-Z01 can be up to 5 folds higher than that of conventional silica gels. Owing to the quantum increase in the adsorbate uptake, the FAM-Z01 has the potential to significantly reduce the footprint of an existing AD plant for the same output capacity. © 2014 Elsevier B.V.

  18. Experimental investigation of high cycle thermal fatigue in a T-junction piping system

    Energy Technology Data Exchange (ETDEWEB)

    Selvam, P. Karthick; Kulenovic, Rudi; Laurien, Eckart [Stuttgart Univ. (Germany). Inst. of Nuclear Technology and Energy Systems (IKE)

    2015-10-15

    High cycle thermal fatigue damage of structure in the vicinity of T-junction piping systems in nuclear power plants is of importance. Mixing of coolant streams at significant temperature differences causes thermal fluctuations near piping wall leading to gradual thermal degradation. Flow mixing in a T-junction is performed. The determined factors result in bending stresses being imposed on the piping system ('Banana effect').

  19. Physical and thermal characteristics of dairy cattle manure.

    Science.gov (United States)

    Sutitarnnontr, Pakorn; Hu, Enzhu; Tuller, Markus; Jones, Scott B

    2014-11-01

    Greenhouse and regulated gas emissions from animal waste are naturally mediated by moisture content and temperature. As with soils, emissions from manure could be readily estimated given the physical, hydraulic, and thermal properties are described by models and microbes and nutrients are not limiting factors. The objectives of this study were to measure and model physical, hydraulic, and thermal properties of dairy manure to support advanced modeling of gas and water fluxes in addition to solute, colloid, and heat transport. A series of soil science measurement techniques were applied to determine a set of fundamental properties of as-excreted dairy cattle manure. Relationships between manure dielectric permittivity and volumetric water content (θ) were obtained using time-domain reflectometry and capacitance-based dielectric measurements. The measured water retention characteristic for cattle manure was similar to organic peat soil. The unsaturated hydraulic conductivity function of dairy manure was inferred from inverse numerical fitting of laboratory manure evaporation results. The thermal properties of dairy manure, including thermal conductivity, thermal diffusivity, and bulk volumetric heat capacity, were also determined using three penta-needle heat pulse probes. The accuracy of the heat capacity measurements was determined from a comparison of theoretical θ, estimated from the measured thermal properties with that determined by the capacitance-based dielectric measurement. These data represent a novel and unique contribution for advancing prediction and modeling capabilities of gas emissions from cattle manure, although the uncertainties associated with the complexities of shrinkage, surface crust formation, and cracking must also be considered. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  20. Efficient cycles for carbon capture CLC power plants based on thermally balanced redox reactors

    KAUST Repository

    Iloeje, Chukwunwike

    2015-10-01

    © 2015 Elsevier Ltd. The rotary reactor differs from most alternative chemical looping combustion (CLC) reactor designs because it maintains near-thermal equilibrium between the two stages of the redox process by thermally coupling channels undergoing oxidation and reduction. An earlier study showed that this thermal coupling between the oxidation and reduction reactors increases the efficiency by up to 2% points when implemented in a regenerative Brayton cycle. The present study extends this analysis to alternative CLC cycles with the objective of identifying optimal configurations and design tradeoffs. Results show that the increased efficiency from reactor thermal coupling applies only to cycles that are capable of exploiting the increased availability in the reduction reactor exhaust. Thus, in addition to the regenerative cycle, the combined CLC cycle and the combined-regenerative CLC cycle are suitable for integration with the rotary reactor. Parametric studies are used to compare the sensitivity of the different cycle efficiencies to parameters like pressure ratio, turbine inlet temperature, carrier-gas fraction and purge steam generation. One of the key conclusions from this analysis is that while the optimal efficiency for regenerative CLC cycle was the highest of the three (56% at 3. bars, 1200. °C), the combined-regenerative cycle offers a trade-off that combines a reasonably high efficiency (about 54% at 12. bars, 1200. °C) with much lower gas volumetric flow rate and consequently, smaller reactor size. Unlike the other two cycles, the optimal compressor pressure ratio for the regenerative cycle is weakly dependent on the design turbine inlet temperature. For the regenerative and combined regenerative cycles, steam production in the regenerator below 2× fuel flow rate improves exhaust recovery and consequently, the overall system efficiency. Also, given that the fuel side regenerator flow is unbalanced, it is more efficient to generate steam from the

  1. Connection between maximum-work and maximum-power thermal cycles

    OpenAIRE

    Gonzalez-Ayala, Julian; Arias-Hernandez, L. A.; Angulo-Brown, F.

    2013-01-01

    We propose a new connection between maximum-power Curzon-Ahlborn thermal cycles and maximum-work reversible cycles. This linkage is built through a mapping between the exponents of a class of heat transfer laws and the exponents of a family of heat capacities depending on temperature. This connection leads to the recovery of known results and to a wide and interesting set of new results for a class of thermal cycles. Among other results we find that it is possible to use analytically closed e...

  2. Life cycle analysis of underground thermal energy storage

    NARCIS (Netherlands)

    Tomasetta, Camilla; van Ree, Derk; Griffioen, Jasper

    2015-01-01

    Underground Thermal Energy Storage (UTES) systems are used to buffer the seasonal difference between heat and cold supply and demand and, therefore, represent an interesting option to conserve energy. Even though UTES are considered environmental friendly solutions they are not completely free of

  3. Influence of creep damage on the low cycle thermal-mechanical fatigue behavior of two tantalum base alloys

    Science.gov (United States)

    Sheffler, K. D.; Doble, G. S.

    1972-01-01

    Low cycle fatigue tests have been performed on the tantalum base alloys T-111 and ASTAR 811C with synchronized, independently programmed temperature and strain cycling. The thermal-mechanical cycles applied fell into three basic categories: these were isothermal cycling, in-phase thermal cycling, and out-of-phase thermal cycling. In-phase cycling was defined as tensile deformation associated with high temperature and compressive deformation with low temperature, while out-of-phase thermal cycling was defined as the reverse case. The in-phase thermal cycling had a pronounced detrimental influence on the fatigue life of both alloys, with the life reduction being greater in the solid solution strengthened T-111 alloy than in the carbide strengthened ASTAR 811C alloy. The out-of-phase tests also showed pronounced effects on the fatigue life of both alloys, although not as dramatic.

  4. Thermal cycling for restorative materials: does a standardized protocol exist in laboratory testing? A literature review.

    Science.gov (United States)

    Morresi, Anna Lucia; D'Amario, Maurizio; Capogreco, Mario; Gatto, Roberto; Marzo, Giuseppe; D'Arcangelo, Camillo; Monaco, Annalisa

    2014-01-01

    In vitro tests continue to be an indispensable method for the initial screening of dental materials. Thermal cycling is one of the most widely used procedures to simulate the physiological aging experienced by biomaterials in clinical practice. Consequently it is routinely employed in experimental studies to evaluate materials' performance. A literature review aimed to elucidate test parameters for in vitro aging of adhesive restorations was performed. This study aims to assess whether or not a standardized protocol of thermal cycling has been acknowledged from a review of the literature. An exhaustive literature search, examining the effect of thermal cycling on restorative dental materials, was performed with electronic database and by hand. The search was restricted to studies published from 1998 to August 2013. No language restrictions were applied. The search identified 193 relevant experimental studies. Only twenty-three studies had faithfully applied ISO standard. The majority of studies used their own procedures, showing only a certain consistency within the temperature parameter (5-55°C) and a great variability in the number of cycles and dwell time chosen. A wide variation in thermal cycling parameters applied in experimental studies has been identified. The parameters selected amongst these studies seem to be done on the basis of convenience for the authors in most cases. A comparison of results between studies would appear to be impossible. The available data suggest that further investigations will be required to ultimately develop a standardized thermal cycling protocol. © 2013 Elsevier Ltd. All rights reserved.

  5. Effect of thermal cycling and disinfection on colour stability of denture base acrylic resin.

    Science.gov (United States)

    Goiato, Marcelo C; Dos Santos, Daniela M; Baptista, Gabriella T; Moreno, Amália; Andreotti, Agda M; Bannwart, Lisiane C; Dekon, Stefan F C

    2013-12-01

    The purpose of this study was to investigate the effect of thermal cycling and disinfection on the colour change of denture base acrylic resin. Four different brands of acrylic resins were evaluated (Onda Cryl, QC 20, Classico and Lucitone). All brands were divided into four groups (n = 7) determined according to the disinfection procedure (microwave, Efferdent, 4% chlorhexidine or 1% hypochlorite). The treatments were conducted three times a week for 60 days. All specimens were thermal cycled between 5 and 55°C with 30-s dwell times for 1000 cycles before and after disinfection. The specimens' colour was measured with a spectrophotometer using the CIE L*a*b* system. The evaluations were conducted at baseline (B), after first thermal cycling (T1 ), after disinfection (D) and after second thermal cycling (T2 ). Colour differences (ΔE) were calculated between T1 and B (T1 B), D and B (DB), and T2 and B (T2 B) time-points.   The samples submitted to disinfection by microwave and Efferdent exhibited the highest values of colour change. There were significant differences on colour change between the time-points, except for the Lucitone acrylic resin. The thermal cycling and disinfection procedures significantly affected the colour stability of the samples. However, all values obtained for the acrylic resins are within acceptable clinical parameters. © 2012 John Wiley & Sons A/S and The Gerodontology Society. Published by John Wiley & Sons Ltd.

  6. Effect of thermal cycling and disinfection on microhardness of acrylic resin denture base.

    Science.gov (United States)

    Goiato, Marcelo Coelho; Dos Santos, Daniela Micheline; Baptista, Gabriella Trunckle; Moreno, Amália; Andreotti, Agda Marobo; Dekon, Stéfan Fiuza de Carvalho

    2013-04-01

    The purpose of this study was to investigate the effect of thermal cycling and disinfection on the microhardness of acrylic resins denture base. Four different brands of acrylic resins were evaluated: Onda Cryl, QC 20, Classico and Lucitone. Each brand of acrylic resin was divided into four groups (n = 7) according to the disinfection method (microwave, Efferdent, 4% chlorhexidine and 1% hypochlorite). Samples were disinfected during 60 days. Before and after disinfection, samples were thermal cycled between 5-55 °C with 30-s dwell times for 1000 cycles. The microhardness was measured using a microhardener, at baseline (B), after first thermal cycling (T1), after disinfection (D) and after second thermal cycling (T2). The microhardness values of all groups reduced over time. QC-20 acrylic resin exhibited the lowest microhardness values. At B and T1 periods, the acrylic resins exhibited statistically greater microhardness values when compared to D and T2 periods. It can be concluded that the microhardness values of the acrylic resins denture base were affected by the thermal cycling and disinfection procedures. However, all microhardness values obtained herein are within acceptable clinical limits for the acrylic resins.

  7. Thermal shock cycling effect on the compressive behaviour of human teeth.

    Science.gov (United States)

    Papanicolaou, G C; Kouveliotis, G; Nikolopoulou, F; Papaefthymiou, K P; Bairami, V; Portan, D V

    2015-02-26

    All ceramic veneers are a common choice that both dentists and patients make for anterior restorations. In the framework of the present study the residual compressive behavior of the above mentioned complex structures after being thermally shock cycled was investigated. An exponential decrease in both compressive stiffness and strength with the thermal shock cycle number was observed. Experimental findings were in good agreement with predicted values. Photomicrographs obtained revealed a different failure mechanism for the pristine and cycled teeth, which is indicative of the susceptible nature of restored teeth to thermal shock. A two-dimensional finite element model designed gave a better insight upon the stress fields in response of thermal or mechanical loadings developed in the oral cavity. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Characteristic of Thermally Reduced Graphene Oxide as Supercapacitors Electrode Materials

    Science.gov (United States)

    Marcelina, Vika; Syakir, Norman; Wyantuti, Santhy; Hartati, Yeni W.; Hidayat, Rahmat; Fitrilawati

    2017-05-01

    We investigated graphene like material named reduced graphene oxide (RGO) as an electrode material by employed graphene oxide (GO). Thin film of GO was prepared on the indium thin oxide (ITO) substrate by spin-coating method using varied concentration of GO that dispersed in water. In order to remove its oxygen contained, GO film was thermally reduced at 200 °C for 1 hour. We used cyclic voltammetry to measure its CV characteristic and estimated its specific capacitance. We obtained the highest specific capacitance of 6.53 mF g-1 that measured from 4 mg ml-1 RGO thin film at scan rate 25 mVs-1.

  9. Connection between maximum-work and maximum-power thermal cycles.

    Science.gov (United States)

    Gonzalez-Ayala, Julian; Arias-Hernandez, L A; Angulo-Brown, F

    2013-11-01

    A new connection between maximum-power Curzon-Ahlborn thermal cycles and maximum-work reversible cycles is proposed. This linkage is built through a mapping between the exponents of a class of heat transfer laws and the exponents of a family of heat capacities depending on temperature. This connection leads to the recovery of known results and to a wide and interesting set of results for a class of thermal cycles. Among other results it was found that it is possible to use analytically closed expressions for maximum-work efficiencies to calculate good approaches to maximum-power efficiencies. Behind the proposed connection is an interpretation of endoreversibility hypothesis. Additionally, we suggest that certain reversible maximum-work cycles depending on working substance can be used as reversible landmarks for FTT maximum-power cycles, which also depend on working substance properties.

  10. Residual Tensile Property of Plain Woven Jute Fiber/Poly(Lactic Acid Green Composites during Thermal Cycling

    Directory of Open Access Journals (Sweden)

    Hideaki Katogi

    2016-07-01

    Full Text Available This study investigated the residual tensile properties of plain woven jute fiber reinforced poly(lactic acid (PLA during thermal cycling. Temperature ranges of thermal cycling tests were 35–45 °C and 35–55 °C. The maximum number of cycles was 103 cycles. The quasi-static tensile tests of jute fiber, PLA, and composite were conducted after thermal cycling tests. Thermal mechanical analyses of jute fiber and PLA were conducted after thermal cycling tests. Results led to the following conclusions. For temperatures of 35–45 °C, tensile strength of composite at 103 cycles decreased 10% compared to that of composite at 0 cycles. For temperatures of 35–55 °C, tensile strength and Young’s modulus of composite at 103 cycles decreased 15% and 10%, respectively, compared to that of composite at 0 cycles. Tensile properties and the coefficient of linear expansion of PLA and jute fiber remained almost unchanged after thermal cycling tests. From observation of a fracture surface, the length of fiber pull out in the fracture surface of composite at 103 cycles was longer than that of composite at 0 cycles. Therefore, tensile properties of the composite during thermal cycling were decreased, probably because of the decrease of interfacial adhesion between the fiber and resin.

  11. A graphic approach to include dissipative-like effects in reversible thermal cycles

    Science.gov (United States)

    Gonzalez-Ayala, Julian; Arias-Hernandez, Luis Antonio; Angulo-Brown, Fernando

    2017-05-01

    Since the decade of 1980's, a connection between a family of maximum-work reversible thermal cycles and maximum-power finite-time endoreversible cycles has been established. The endoreversible cycles produce entropy at their couplings with the external heat baths. Thus, this kind of cycles can be optimized under criteria of merit that involve entropy production terms. Meanwhile the relation between the concept of work and power is quite direct, apparently, the finite-time objective functions involving entropy production have not reversible counterparts. In the present paper we show that it is also possible to establish a connection between irreversible cycle models and reversible ones by means of the concept of "geometric dissipation", which has to do with the equivalent role of a deficit of areas between some reversible cycles and the Carnot cycle and actual dissipative terms in a Curzon-Ahlborn engine.

  12. Regenerative characteristics of magnetic or gas Stirling refrigeration cycle

    Science.gov (United States)

    Chen, J.; Yan, Z.

    A general criterion to distinguish whether a Stirling refrigeration cycle possesses the condition of perfect regeneration is given. It is proven using the criterion that a Stirling refrigeration cycle using a simple paramagnetic or ferromagnetic material as the working substance possesses the condition of perfect regeneration, as does a Stirling refrigeration cycle using an ideal or van der Waals gas as the working substance. However, a Stirling refrigeration cycle using a gas which is described by the Redlich-Kwong, Beattie-Bridgeman, Benedict-Webb-Rubin, Dieterici, Berthelot, or Martin-Hou equation as the working substance does not possess the condition of perfect regeneration and its coefficient of performance is always smaller than that of the Carnot refrigeration cycle for the same temperature range. Moreover, the effect of non-perfect regeneration on the level of refrigeration and the coefficient of performance of a Stirling refrigeration cycle is expounded using a strict equation of state.

  13. Effects of thermal treatments on donkey milk nutritional characteristics.

    Science.gov (United States)

    Polidori, Paolo; Vincenzetti, Silvia

    2013-12-01

    Human breast milk is the best nutritional support to ensure right development and influence immune status of the newborn infant. However, when it is not possible to breast feed it may be necessary to use commercial infant formulas that mimic, where possible, the levels and types of nutrients present in human milk. Despite this, some formula-fed infants develop allergy and/or atopic disease compared to breast-fed infants. Most infants with cow's milk protein allergy (CMPA) develop symptoms before 1 month of age, often within 1 week after introduction of cow's milk-based formula. Donkey milk may be considered a good substitute for cow's milk in feeding children with CMPA since its composition is very similar to human milk. An in-depth analysis of the donkey milk protein profile has been performed in this study. The interest was focused on the milk proteins considered safe for the prevention and treatment of various disorders in human. Since donkey milk supply is related to its seasonal availability during the year, in this study were evaluated the effects of different thermal treatments on the protein fractions of donkey milk. The results obtained in fresh, frozen, powdered and lyophilized donkey milk showed different values in total proteins, caseins, whey proteins and lysozyme content. This study demonstrated the possibility of using lyophilization in order to maintain the nutritional characteristics of donkey milk. The article presents some promising patents on the effects of thermal treatments on donkey milk nutritional characteristics.

  14. Simulation and parametric optimisation of thermal power plant cycles

    OpenAIRE

    Kumar, P. Ravindra; Raju, V. Ramachandra; Kumar, N. Ravi

    2016-01-01

    The objective of the paper is to analyse parametric studies and optimum steam extraction pressures of three different (subcritical, supercritical and ultra-supercritical) coal fired power plant cycles at a particular main steam temperature of 600 °C by keeping the reheat temperature at 537 °C and condenser pressure at 0.09 bar as constant. In order to maximize the heat rate gain possible with supercritical and ultra-supercritical steam conditions, eight stages of feed water heater arrangement...

  15. Influence of specimens' geometry and materials on the thermal stresses in dental restorative materials during thermal cycling.

    Science.gov (United States)

    Fabris, Douglas; Souza, Júlio C M; Silva, Filipe S; Fredel, Márcio; Gasik, Michael; Henriques, Bruno

    2018-02-01

    Thermal cycling is widely used to simulate the aging of restorative materials corresponding to the changes of temperature in the oral cavity. However, test parameters present in literature vary considerably, which prevents comparison between different reports. The aim of this work is to assess the influence of the specimens' geometry and materials on the thermal stresses developed during thermal cycling tests. Finite elements method was used to simulate the conditions of thermal cycling tests for three different sample geometries: a three-points bending test sample, a cylinder rod and more complex shape of a restoration crown. Two different restorative systems were considered: all-ceramic (zirconia coupled with porcelain) and metal-ceramic (CoCrMo alloy coupled with porcelain). The stress state of each sample was evaluated throughout the test cycle. The results show that the sample geometry has great influence on the stress state, with difference of up to 230% in the maximum stress between samples of the same composition. The location of maximum stress also changed from the interface between materials to the external wall. Maximum absolute stress values were found to vary between 2 and 4MPa, which might not be critical even for ceramics. During multi-cycle testing these stresses would cause different fatigue in various locations. The zirconia-based specimens and zirconia-based restoration (crown) exhibited the most similar stress states. Thus it might be recommended to use these geometries for fast screening of the materials for this type of restorations. The selection of specimens' geometry and materials should be carefully considered when aging conditions close to clinical ones want to be simulated. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Deep greedy learning under thermal variability in full diurnal cycles

    Science.gov (United States)

    Rauss, Patrick; Rosario, Dalton

    2017-08-01

    We study the generalization and scalability behavior of a deep belief network (DBN) applied to a challenging long-wave infrared hyperspectral dataset, consisting of radiance from several manmade and natural materials within a fixed site located 500 m from an observation tower. The collections cover multiple full diurnal cycles and include different atmospheric conditions. Using complementary priors, a DBN uses a greedy algorithm that can learn deep, directed belief networks one layer at a time and has two layers form to provide undirected associative memory. The greedy algorithm initializes a slower learning procedure, which fine-tunes the weights, using a contrastive version of the wake-sleep algorithm. After fine-tuning, a network with three hidden layers forms a very good generative model of the joint distribution of spectral data and their labels, despite significant data variability between and within classes due to environmental and temperature variation occurring within and between full diurnal cycles. We argue, however, that more questions than answers are raised regarding the generalization capacity of these deep nets through experiments aimed at investigating their training and augmented learning behavior.

  17. Test bench for thermal cycling of 10 kV silicon carbide power modules

    DEFF Research Database (Denmark)

    Sønderskov, Simon Dyhr; Jørgensen, Asger Bjørn; Maarbjerg, Anders Eggert

    2016-01-01

    This paper presents a test bench for lifetime investigation of 10 kV silicon carbide power modules. The test bench subjects high voltage switching operation to the modules while power cycling. Thus both a thermal and electrical operating point is emulated. The power cycling setup features offline...... made to validate the performance of the on-state voltage measurement and the thermal model. Issues are revealed in the form of common mode currents in gate drive supply, which should be remedied. Finally a new operating point for power cycling is suggested to better stress the power modules....... measurement of on-state voltages and direct real-time measurement of die surface temperatures, enabled by fiber optical sensors, which are built into the power modules. A thermal model of the module prototypes, based on the temperature measurements, is established. Independent verification steps have been...

  18. Thermal Characteristics of Hyperaccumulator and Fate of Heavy Metals during Thermal Treatment of Sedum plumbizincicola.

    Science.gov (United States)

    Zhong, Daoxu; Zhong, Zhaoping; Wu, Longhua; Xue, Hui; Song, Zuwei; Luo, Yongming

    2015-01-01

    Thermal treatment is one of the most promising disposal techniques for heavy metal- (HM)-enriched hyperaccumulators. However, the thermal characteristics and fate of HMs during thermal treatment of hyperaccumulator biomass need to be known in detail. A horizontal tube furnace was used to analyze the disposal process of hyperaccumulator biomass derived from a phyto-extracted field in which the soil was moderately contaminated with heavy metals. Different operational conditions regarding temperature and gas composition were tested. A thermo-dynamic analysis by advanced system for process engineering was performed to predict HM speciation during thermal disposal and SEM-EDS, XRD and sequential chemical extraction were used to characterize the heavy metals. The recovery of Zn, Pb and Cd in bottom ash decreased with increasing temperature but recovery increased in the fly ash. Recovery of Zn, Pb and Cd fluctuated with increasing air flow rate and the metal recovery rates were higher in the fly ash than the bottom ash. Most Cl, S, Fe, Al and SiO2 were found as alkali oxides, SO2, Fe2(SO4)3, iron oxide, Ca3Al2O6, K2SiO3 and SiO2 instead of reacting with HMs. Thus, the HMs were found to occur as the pure metals and their oxides during the combustion process and as the sulfides during the reducing process.

  19. Study of a Liquid Plug-Flow Thermal Cycling Technique Using a Temperature Gradient-Based Actuator

    Directory of Open Access Journals (Sweden)

    Yusuke Fuchiwaki

    2014-10-01

    Full Text Available Easy-to-use thermal cycling for performing rapid and small-volume DNA amplification on a single chip has attracted great interest in the area of rapid field detection of biological agents. For this purpose, as a more practical alternative to conventional continuous flow thermal cycling, liquid plug-flow thermal cycling utilizes a thermal gradient generated in a serpentine rectangular flow microchannel as an actuator. The transit time and flow speed of the plug flow varied drastically in each temperature zone due to the difference in the tension at the interface between temperature gradients. According to thermal distribution analyses in microfluidics, the plug flow allowed for a slow heating process, but a fast cooling process. The thermal cycle of the microfluid was consistent with the recommended temperature gradient for PCR. Indeed, amplification efficiency of the plug flow was superior to continuous flow PCR, and provided an impressive improvement over previously-reported flow microchannel thermal cycling techniques.

  20. A thermal model for the seasonal nitrogen cycle on Triton

    Science.gov (United States)

    Hansen, Candice J.; Paige, David A.

    1992-01-01

    The seasonal N2-cycle model presently used to characterize such observed phenomena on Triton as atmospheric pressure and surface albedo features at the time of the Voyager encounter incorporates diurnal and seasonal subsurface heat conduction, and can account for the heat capacity of N2 frost deposits. The results obtained by this model differ from those of previous studies in that they do not predict the seasonal freezing-out of the Triton atmosphere; even for a wide range of input parameters, the bright southern polar cap is seen as rather unlikely to be N2. The results support the microphysical arguments for the presence of either dark or smooth translucent N2 frosts on the Triton surface.

  1. Effects of Radiation and Long-Term Thermal Cycling on EPC 1001 Gallium Nitride Transistors

    Science.gov (United States)

    Patterson, Richard L.; Scheick, Leif; Lauenstein, Jean-Marie; Casey, Megan; Hammoud, Ahmad

    2012-01-01

    Electronics designed for use in NASA space missions are required to work efficiently and reliably under harsh environment conditions. These include radiation, extreme temperatures, and thermal cycling, to name a few. Data obtained on long-term thermal cycling of new un-irradiated and irradiated samples of EPC1001 gallium nitride enhancement-mode transistors are presented. This work was done by a collaborative effort including GRC, GSFC, and support the NASA www.nasa.gov 1 JPL in of Electronic Parts and Packaging (NEPP) Program

  2. A study on the fracture mechanism of smart composite under thermal shock cycles using AE technique

    Energy Technology Data Exchange (ETDEWEB)

    Lee, J.K.; Lee, S.P. [School of Mechanical Engineering, Dongeui Univ., Busan (Korea); Park, Y.C. [School of Mechanical Engineering, Donga Univ., Busan (Korea)

    2005-07-01

    A smart material is used as spectacle frames and brassiere frames, and partly in medical supplies because of its shape memory effect. The smart composite can be used on the wing of an airplane instead of the existing aluminium to control crack propagation. In this study, the smart composite was fabricated by a hot press method. TiNi alloy as reinforcement and Al6061 as matrix were used, respectively. The mechanical properties of the smart composite under thermal shock cycles were evaluated. In addition, acoustic emission techniques were also used to clarify the damage behavior of the smart composite under thermal shock cycles nondestructively. (orig.)

  3. Thermal Cycling and High Temperature Reverse Bias Testing of Control and Irradiated Gallium Nitride Power Transistors

    Science.gov (United States)

    Patterson, Richard L.; Boomer, Kristen T.; Scheick, Leif; Lauenstein, Jean-Marie; Casey, Megan; Hammoud, Ahmad

    2014-01-01

    The power systems for use in NASA space missions must work reliably under harsh conditions including radiation, thermal cycling, and exposure to extreme temperatures. Gallium nitride semiconductors show great promise, but information pertaining to their performance is scarce. Gallium nitride N-channel enhancement-mode field effect transistors made by EPC Corporation in a 2nd generation of manufacturing were exposed to radiation followed by long-term thermal cycling and testing under high temperature reverse bias conditions in order to address their reliability for use in space missions. Result of the experimental work are presented and discussed.

  4. Effects of Thermal Cycling on Control and Irradiated EPC 2nd Generation GaN FETs

    Science.gov (United States)

    Patterson, Richard L.; Scheick, Leif; Lauenstein, Jean-Marie; Casey, Megan; Hammoud, Ahmad

    2013-01-01

    The power systems for use in NASA space missions must work reliably under harsh conditions including radiation, thermal cycling, and exposure to extreme temperatures. Gallium nitride semiconductors show great promise, but information pertaining to their performance is scarce. Gallium nitride N-channel enhancement-mode field effect transistors made by EPC Corporation in a 2nd generation of manufacturing were exposed to radiation followed by long-term thermal cycling in order to address their reliability for use in space missions. Results of the experimental work are presented and discussed.

  5. Thermal cycling and strain behaviour of AA6061-20% SiC(w) composite

    Energy Technology Data Exchange (ETDEWEB)

    Bonollo, F.; Ceschini, L.; Garagnani, G.L.; Persiani, F.; Zambon, A. (Padua Univ. (Italy). Dip. di Innovazione Meccanica e Gestionale Bologna Univ. (Italy). Ist. di Metallurgia Bologna Univ. (Italy). Dip. di Ingegneria delle Costruzioni Meccaniche, Nucleari, Aeronautiche e di Metallurgia)

    1992-12-01

    This paper describes a study on the effect of thermal cycling on the microstructure and mechanical properties of the fiber reinforced aluminium alloy composite, AA6061 - 20% SiC(w), tested between 100 and 450 degrees C under constant stress (0 to 30 MPa). The test specimens were obtained from extruded bars produced by powder metallurgy. Two specimen orientations were chosen and investigated - longitudinal and transverse. Thermal cycling, carried out by means of suitably designed and assembled test equipment, was aimed at the evaluation of elongation versus extrusion direction, and hardness variation (HR 330N) versus the number of cycles. The microstructural changes in the composite were analyzed by employing light microscopy, scanning electron microscopy, image analysis and transmission electron microscopy. It was observed that: thermal cycling under stress induced very high tensile elongations; significant deformations were also achieved without external loading; there was a correlation among the thermal cycling variables, specimen orientation and applied stress; a re-orientation process occurred along the applied stress direction.

  6. Effect of Thermal Cycling on the Tensile Behavior of Polymer Composites Reinforced by Basalt and Carbon Fibers

    Science.gov (United States)

    Khalili, S. Mohammad Reza; Najafi, Moslem; Eslami-Farsani, Reza

    2017-01-01

    The aim of the present work was to investigate the effect of thermal cycling on the tensile behavior of three types of polymer-matrix composites — a phenolic resin reinforced with woven basalt fibers, woven carbon fibers, and hybrid basalt and carbon fibers — in an ambient environment. For this purpose, tensile tests were performed on specimens previously subjected to a certain number of thermal cycles. The ultimate tensile strength of the specimen reinforced with woven basalt fibers had by 5% after thermal cycling, but the strength of the specimen with woven carbon fibers had reduced to a value by 11% higher than that before thermal cycling.

  7. Comparison of the regulated air pollutant emission characteristics of real-world driving cycle and ECE cycle for motorcycles

    Science.gov (United States)

    Chiang, Hung-Lung; Huang, Pei-Hsiu; Lai, Yen-Ming; Lee, Ting-Yi

    2014-04-01

    Motorcycles are an important means of transportation, and their numbers have increased significantly in recent years. However, motorcycles can emit significant amounts of air pollutants; therefore, the emission characteristics and driving patterns of motorcycles are necessary baseline information for the implementation of control measures for motorcycles in urban areas. The selected motorcycles were equipped with global positioning systems (GPS) to obtain speed-time data for determination of the characteristics of real-world driving parameters, and an on-board exhaust gas analyser with data logger was employed to determine the instantaneous concentration of regulated air pollutants from motorcycle exhaust. Results indicated that the time proportions of acceleration, cruising, and deceleration are different from those of the Economic Commission for Europe (ECE) driving cycle, and the time percentages of acceleration and deceleration of the ECE cycle are much less than those in Taichung city. In general, the emission factors of the Taichung motorcycle driving cycle (TMDC) were higher HC and lower NOx emission than those of the ECE cycle. The average fuel consumption of tested motorcycles on three roads during workdays was 5% higher than that on weekends. The fuel consumption in the real-world motorcycle driving cycle was also about 7% higher than that of the ECE cycle, which again indicates that the ECE cycle is unsuitable for measuring fuel consumption in the Taichung metropolitan area. Therefore, understanding the local driving cycle is necessary for developing accurate emission data for air pollution control measures for urban areas.

  8. Effects of mechanical and thermal cycling on composite and hybrid laminates with residual stresses

    Science.gov (United States)

    Daniel, I. M.; Liber, T.

    1977-01-01

    The effects of tensile load cycling and thermal cycling on residual stiffness and strength properties of the following composite and hybrid angle-ply laminates were studied: boron/epoxy, boron/polyimide, graphite/low-modulus epoxy, graphite/high-modulus epoxy, graphite/polyimide, S-glass/epoxy, graphite/Kevlar 49/epoxy, and graphite/S-glass/epoxy. Specimens of the first six types were mechanically cycled up to 90% of static strength. Those that survived 10 million cycles were tested statically to failure, and no significant changes in residual strength and modulus were noted. Specimens of all types were subjected to thermal cycling between room temperature and 411 K for the epoxy-matrix composites and 533 K for the polyimide-matrix composites. The residual strength and stiffness remained largely unchanged, except for the graphite/low-modulus epoxy, which showed reductions in both of approximately 35%. When low-temperature thermal cycling under tensile load was applied, there was a noticeable reduction in modulus and strength in the graphite/low-modulus epoxy and some strength reduction in the S-glass/epoxy.

  9. Comparison of the characteristics of HVOF and plasma thermal spray

    Energy Technology Data Exchange (ETDEWEB)

    Fincke, J.R.; Swank, W.D.; Haggard, D.C. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1994-12-31

    In spraying oxygen sensitive materials, such as WC:Co it is often observed that the carbide fraction present in the deposit is significantly less than in the original particles. This lowers the hardness of the coating, resulting in inferior wear resistance. The cause is the in-flight, high temperature decomposition of carbides by reaction with entrained oxygen. The degree of decomposition is determined by a combination of particle temperature, residence time and entrainment characteristics of the jet. The fundamental differences between HVOF and plasma thermal spray are examined in this context. Even though the HVOF process may actually subject a particle to greater oxygen exposure than plasma spraying, the lower particle temperatures experienced lead to coatings which exhibit less carbide loss than plasma sprayed coatings fabricated in air.

  10. Models for describing the thermal characteristics of building components

    DEFF Research Database (Denmark)

    Jimenez, M.J.; Madsen, Henrik

    2008-01-01

    Outdoor testing of buildings and building components under real weather conditions provides useful information about their dynamic performance. Such knowledge is needed to properly characterize the heat transfer dynamics and provides useful information for implementing energy saving strategies...... of these approaches may therefore be very useful for selecting a suitable approach for each particular case. This paper presents an overview of models that can be applied for modelling the thermal characteristics of buildings and building components using data from outdoor testing. The choice of approach depends......, for example. For the analysis of these tests, dynamic analysis models and methods are required. However, a wide variety of models and methods exists, and the problem of choosing the most appropriate approach for each particular case is a non-trivial and interdisciplinary task. Knowledge of a large family...

  11. Life cycle monitoring of lithium-ion polymer batteries using cost-effective thermal infrared sensors with applications for lifetime prediction

    Science.gov (United States)

    Zhou, Xunfei; Malik, Anav; Hsieh, Sheng-Jen

    2017-05-01

    Lithium-ion batteries have become indispensable parts of our lives for their high-energy density and long lifespan. However, failure due to from abusive usage conditions, flawed manufacturing processes, and aging and adversely affect battery performance and even endanger people and property. Therefore, battery cells that are failing or reaching their end-of-life need to be replaced. Traditionally, battery lifetime prediction is achieved by analyzing data from current, voltage and impedance sensors. However, such a prognostic system is expensive to implement and requires direct contact. In this study, low-cost thermal infrared sensors were used to acquire thermographic images throughout the entire lifetime of small scale lithium-ion polymer batteries (410 cycles). The infrared system (non-destructive) took temperature readings from multiple batteries during charging and discharging cycles of 1C. Thermal characteristics of the batteries were derived from the thermographic images. A time-dependent and spatially resolved temperature mapping was obtained and quantitatively analyzed. The developed model can predict cycle number using the first 10 minutes of surface temperature data acquired through infrared imaging at the beginning of the cycle, with an average error rate of less than 10%. This approach can be used to correlate thermal characteristics of the batteries with life cycles, and to propose cost-effective thermal infrared imaging applications in battery prognostic systems.

  12. Physicochemical and thermal characteristics of Australian chia seed oil.

    Science.gov (United States)

    Timilsena, Yakindra Prasad; Vongsvivut, Jitraporn; Adhikari, Raju; Adhikari, Benu

    2017-08-01

    Physicochemical and thermal characteristics of Australian chia seed oil (CSO) were studied. The specific gravity, viscosity and refractive index of CSO at ambient temperature were 0.93, 43.2mPa.s and 1.48, respectively. The acid, peroxide, saponification and iodine values and unsaponifiable matter content of CSO were 2.54gKOH/kg oil, 4.33meqO 2 /kg oil, 197gKOH/kg oil, 204gI 2 /kg oil and 1.12%, respectively. α-linolenic acid is the most abundant fatty acid comprising (64.39% of total oil) followed by linoleic acid (21.46%), while saturated fatty acid content is less than 10%. This CSO contained twelve triacylglycerols (TAGs) out of which trilinolenin (αLnαLnαLn) was the most abundant comprising 33.2% of total TAG. Melting point and melting enthalpy of CSO were -34°C and 77.48J/g, respectively. CSO remained stable up to 300°C with negligible degradation. Due to these physicochemical and thermal properties, CSO is an excellent source of essential fatty acids for food industries. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Imposed Thermal Fatigue and Post-Thermal-Cycle Wear Resistance of Biomimetic Gray Cast Iron by Laser Treatment

    Science.gov (United States)

    Sui, Qi; Zhou, Hong; Zhang, Deping; Chen, Zhikai; Zhang, Peng

    2017-08-01

    The present study aims to create coupling biomimetic units on gray cast iron substrate by laser surface treatment (LST). LSTs for single-step (LST1) and two-step (LST2) processes, were carried out on gray cast iron in different media (air and water). Their effects on microstructure, thermal fatigue, and post-thermal-cycle wear (PTW) resistance on the specimens were studied. The tests were carried out to examine the influence of crack-resistance behavior as well as the biomimetic surface on its post-thermal-cycle wear behavior and different units, with different laser treatments for comparison. Results showed that LST2 enhanced the PTW behaviors of gray cast iron, which then led to an increase in its crack resistance. Among the treated cast irons, the one treated by LST2 in air showed the lowest residual stress, due to the positive effect of the lower steepness of the thermal gradient. Moreover, the same specimen showed the best PTW performance, due to its superior crack resistance and higher hardness as a result of it.

  14. A feasible thermal-cycle screening system for cryogenic semiconductor components

    Science.gov (United States)

    Wu, Ligang; Liu, Dafu; Huang, Yimin; Zhu, Sangen; Gong, Haimei

    2005-01-01

    For the limit of its lifetime, the Stirling cooler is operated on the intermittent mode in satellite in some cases. Thus such cryogenic semiconductor components as HgCdTe mid or long wavelength infrared (IR) detectors are subjected to thousands of repeated thermal cycles from below -173°C to room temperature. Therefore, a series of experiments focused on quality, performance and reliability are essential in order to satisfy the reasonable requirements. Accordingly, a feasible thermal cycle screening system is put forward. And a vast experimental data show that thermal cycle tests play the most effective role in the environment stress screen (ESS). In this paper, we introduce the system to help to study the main failure mechanisms and improve the performance of the semiconductor components. Such main failure mechanisms as solder-ball invalidation encountered commonly in the detector modules, which is due to the large thermal expansion coefficient mismatch among different materials. The thermal cycle system is based on the principle of heat exchange. We expect HgCdTe IR detectors be cooled to lower than -173°C and heated to room temperature in a few minutes. Above all, we simulate the heating and cooling system through finite element method (FEM). As a result, the computations reveal that the IR detectors can be heated and cooled at a higher rate than expected. A consequent design of the entire system is founded on the simulation. At last, we adjust the mechanical structure of heat exchange system to the adaptive state to accomplish the ESS. The thermal cycle screening system includes an autocontrol part and a test part. The autocontrol part is adopted to realize the heat exchange between IR detectors and the environment, and the test one to inspect the temperature and electrical parameters of these detectors. And at least four IR detector samples can be screened at one time.

  15. Thermal Cycling Behavior of Quasi-Columnar YSZ Coatings Deposited by PS-PVD

    Science.gov (United States)

    Yang, Jiasheng; Zhao, Huayu; Zhong, Xinghua; Shao, Fang; Liu, Chenguang; Zhuang, Yin; Ni, Jinxing; Tao, Shunyan

    2017-01-01

    Columnar-structured thermal barrier coatings, owing to their high strain tolerance, are expected for their potential possibilities to substantially extend turbine lives and improve engine efficiencies. In this paper, plasma spray-physical vapor deposition (PS-PVD) process was used to deposit yttria partially stabilized zirconia (YSZ) coatings with quasi-columnar structures. Thermal cyclic tests on burner rigs and thermal shock tests by heating and water-quenching method were involved to evaluate the thermal cycling and thermal shock behaviors of such kind of structured thermal barrier coatings (TBCs). Evolution of the microstructures, phase composition, residual stresses and failure behaviors of quasi-columnar YSZ coatings before and after the thermal tests was investigated. The quasi-columnar coating obtained had an average life of around 623 cycles when the spallation area reached about 10% of the total coating surface during burner rig tests with the coating surface temperature of 1250 °C. Failure of the coating is mainly due to the break and pull-out of center columnar segments.

  16. Oscillatory Zoning of La- and Y- doped Titanite During Thermal Cycling Experiments

    Science.gov (United States)

    Wickland, T. D.; Glazner, A. F.

    2016-12-01

    Titanite is an important accessory mineral in silicic igneous rocks because it can hold a large proportion of the rare earth element (REE) budget compared to its modal abundance. It typically exhibits strong oscillatory zoning, suggesting variable thermal conditions or open-system addition during crystallization. We performed a set of thermal cycling experiments on La- and Y- (proxy for MREE) doped titanite in a basaltic melt and observed oscillatory zoned rims forming on preexisting, low-REE titanite seeds. Thermal cycling promotes crystal coarsening through precipitation-dissolution processes which may contribute to phenocrystic textures commonly seen in igneous rocks. Using a 1-atmosphere gas-mixing furnace, experiments were cycled ±10°C from 1220°C with a 96-minute period for 1-60 cycles. In these experiments, the number of oscillatory zones in titanite rims equaled the number of thermal cycles. Rims are typically 4-5 mm in wavelength and are euhedral compared to the core anhedral seeds. Oscillatory zones exist within sectored zones of titanite and consist of a bright and dark section determined by backscattered electron images. REE crystal/glass partition coefficients (D-values) determined by FE-microprobe reached 3 in the titanite rims and varied by 0.4 wt% across zones. D-values for Y are 2 orders of magnitude lower in experimentally grown titanite than in natural igneous titanite from silica-rich glass. Titanite incorporates large amounts (103-104 times chondrite) of REE by the coupled substitutions of Ca2+ + Ti4+ = (REE, Y)3+ + (Fe, Al) 3+. D-values negatively correlate with temperature and positively correlate with SiO2 glass content. Thus, high run temperatures and silica-poor glass ( 40 wt%) likely diminish experimental D-values. Although thermal cycling does not appear to increase REE uptake in the titanite-basalt system, it does correlate to the oscillatory zoning patterns common in igneous titanite.

  17. Evaluation of the of thermal shock resistance of a castable containing andalusite aggregates by thermal shock cycles; Avaliacao da resistencia ao dano por choque termico por ciclagem de um concreto refratario contendo agregados de andaluzita

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, G.C.R.; Santos, E.M.B.; Ribeiro, S., E-mail: girribeiro@yahoo.com.br [Universidade de Sao Paulo (DEMAR/EEL/USP), Lorena, SP (Brazil). Escola de Engenharia de. Departamento de Engenharia de Materiais; Resende, W.S. [Industrias Brasileiras de Artigos Refratarios (IBAR), Lorena, SP (Brazil); Rodrigues, J.A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil)

    2011-07-01

    The thermal shock resistance of refractory materials is one of the most important characteristics that determine their performance in many applications, since abrupt and drastic differences in temperature can damage them. Resistance to thermal shock damage can be evaluated based on thermal cycles, i.e., successive heating and cooling cycles followed by an analysis of the drop in Young's modulus occurring in each cycle. The aim of this study was to evaluate the resistance to thermal shock damage in a commercial refractory concrete with andalusite aggregate. Concrete samples that were sintered at 1000 deg C and 1450 deg C for 5 hours to predict and were subjected to 30 thermal shock cycles, soaking in the furnace for 20 minutes at a temperature of 1000 deg C, and subsequent cooling in circulating water at 25 deg C. The results showed a decrease in Young's modulus and rupture around 72% for samples sintered at 1000 ° C, and 82% in sintered at 1450 ° C. The refractory sintered at 1450 deg C would show lower thermal shock resistance than the refractory sintered at 1000 deg C. (author)

  18. Monitoring chemical degradation of thermally cycled glass-fibre composites using hyperspectral imaging

    Science.gov (United States)

    Papadakis, V. M.; Müller, B.; Hagenbeek, M.; Sinke, J.; Groves, R. M.

    2016-04-01

    Nowadays, the application of glass-fibre composites in light-weight structures is growing. Although mechanical characterizations of those structures are commonly performed in testing, chemical changes of materials under stresses have not yet been well documented. In the present work coupon tests and Hyperspectral Imaging (HSI) have been used to categorise possible chemical changes of glass-fibre reinforced polymers (GFRP) which are currently used in the aircraft industry. HSI is a hybrid technique that combines spectroscopy with imaging. It is able to detect chemical degradation of surfaces and has already been successfully applied in a wide range of fields including astronomy, remote sensing, cultural heritage and medical sciences. GFRP specimens were exposed to two different thermal loading conditions. One thermal loading condition was a continuous thermal exposure at 120°C for 24h, 48 h and 96h, i.e. ageing at a constant temperature. The other thermal loading condition was thermal cycling with three different numbers of cycles (4000, 8000, 12000) and two temperature ranges (0°C to 120°C and -25°C to 95°C). The effects of both conditions were measured using both HSI and interlaminar shear (ILSS) tests. No significant changes of the physical properties of the thermally cycled GFRP specimens were detected using interlaminar shear strength tests and optical microscopy. However, when using HIS, differences of the surface conditions were detected. The results showed that the different thermal loading conditions could be successfully clustered in different colours, using the HSI linear unmixing technique. Each different thermal loading condition showed a different chemical degradation level on its surface which was indicated using different colours.

  19. Synergistic effects of ultraviolet radiation, thermal cycling and atomic oxygen on altered and coated Kapton surfaces

    Science.gov (United States)

    Dever, Joyce A.; Bruckner, Eric J.; Rodriguez, Elvin

    1992-01-01

    The photovoltaic (PV) power system for Space Station Freedom (SSF) uses solar array blankets which provide structural support for the solar cells and house the electrical interconnections. In the low earth orbital (LEO) environment where SSF will be located, surfaces will be exposed to potentially damaging environmental conditions including solar ultraviolet (UV) radiation, thermal cycling, and atomic oxygen. It is necessary to use ground based tests to determine how these environmental conditions would affect the mass loss and optical properties of candidate SSF blanket materials. Silicone containing, silicone coated, and SiO(x) coated polyimide film materials were exposed to simulated LEO environmental conditions to determine their durability and whether the environmental conditions of UV, thermal cycling and oxygen atoms act synergistically on these materials. A candidate PV blanket material called AOR Kapton, a polysiloxane polyimide cast from a solution mixture, shows an improvement in durability to oxygen atoms erosion after exposure to UV radiation or thermal cycling combined with UV radiation. This may indicate that the environmental conditions react synergistically with this material, and the damage predicted by exposure to atomic oxygen alone is more severe than that which would occur in LEO where atomic oxygen, thermal cycling and UV radiation are present together.

  20. Reducing dislocations in semiconductors utilizing repeated thermal cycling during multistage epitaxial growth

    Science.gov (United States)

    Fan, John C. C.; Tsaur, Bor-Yeu; Gale, Ronald P.; Davis, Frances M.

    1986-12-30

    Dislocation densities are reduced in growing semiconductors from the vapor phase by employing a technique of interrupting growth, cooling the layer so far deposited, and then repeating the process until a high quality active top layer is achieved. The method of interrupted growth, coupled with thermal cycling, permits dislocations to be trapped in the initial stages of epitaxial growth.

  1. Mechanical and thermal cycling effects on the flexural strength of glass ceramics fused to titanium

    NARCIS (Netherlands)

    Vasquez, Vanessa; Ozcan, Mutlu; Nishioka, Renato; Souza, Rodrigo; Mesquita, Alfredo; Pavanelli, Carlos

    This study evaluated the effects of mechanical and thermal cycling on the flexural strength (ISO 9693) of three brands of ceramics fused to commercially pure titanium (cpTi). Metallic frameworks of 25 x 3 x 0.5 mm dimensions (N = 84) were cast in cpTi, followed by 150-mu m aluminum oxide airborne

  2. Measured thermal and fast neutron fluence rates for ATF-1 holders during ATR cycle 160A

    Energy Technology Data Exchange (ETDEWEB)

    Walker, B. J. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Miller, D. T. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2017-06-06

    This report contains the thermal (2200 m/s) and fast (E>1MeV) neutron fluence rate data for the ATF-1 holders located in core for ATR Cycle 160A which were measured by the Radiation Measurements Laboratory (RML).

  3. Development of Thermal Performance Analysis Computer Program on Turbine Cycle of Yoggwang 3,4 Units

    Energy Technology Data Exchange (ETDEWEB)

    Hong, S.Y.; Choi, K.H.; Jee, M.H.; Chung, S.I. [Korea Electric Power Research Institute, Taejon (Korea)

    2002-07-01

    The objective of the study ''Development of Thermal Performance Analysis Computer Program on Turbine Cycle of Yonggwang 3,4 Units'' is to utilize computerized program to the performance test of the turbine cycle or the analysis of the operational status of the thermal plants. In addition, the result can be applicable to the analysis of the thermal output at the abnormal status and be a powerful tool to find out the main problems for such cases. As a results, the output of this study can supply the way to confirm the technical capability to operate the plants efficiently and to obtain the economic gains remarkably. (author). 27 refs., 73 figs., 6 tabs.

  4. Finite Element Modeling of Thermal Cycling Induced Microcracking in Carbon/Epoxy Triaxial Braided Composites

    Science.gov (United States)

    Zhang, Chao; Binienda, Wieslaw K.; Morscher, Gregory; Martin, Richard E.

    2012-01-01

    The microcrack distribution and mass change in PR520/T700s and 3502/T700s carbon/epoxy braided composites exposed to thermal cycling was evaluated experimentally. Acoustic emission was utilized to record the crack initiation and propagation under cyclic thermal loading between -55 C and 120 C. Transverse microcrack morphology was investigated using X-ray Computed Tomography. Different performance of two kinds of composites was discovered and analyzed. Based on the observations of microcrack formation, a meso-mechanical finite element model was developed to obtain the resultant mechanical properties. The simulation results exhibited a decrease in strength and stiffness with increasing crack density. Strength and stiffness reduction versus crack densities in different orientations were compared. The changes of global mechanical behavior in both axial and transverse loading conditions were studied. Keywords: Thermal cycles; Microcrack; Finite Element Model; Braided Composite

  5. General performance characteristics of an irreversible ferromagnetic Stirling refrigeration cycle

    NARCIS (Netherlands)

    Lin, G.; Bruck, E.H.; Tegus, O.; Zhang, L.

    2004-01-01

    A new magnetic-refrigeration-cycle model using ferromagnetic materials as a cyclic working substance is set up, in which finite-rate heat transfer, heat leak and regeneration time are taken into account. On the basis of the thermodynamic properties of a ferromagnetic material, the general

  6. Cycle life characteristics of Li-TiS2 cells

    Science.gov (United States)

    Deligiannis, Frank; Shen, D.; Huang, C. K.; Surampudi, S.

    1991-01-01

    The development of lithium ambient temperature rechargeable cells is discussed. During the development process, we hope to gain a greater understanding of the materials and the properties of the Li-TiS2 cell and its components. The design will meet the requirements of 100 Wh/Kg and 1000 cycles, at 50 percent depth-of-discharge, by 1995.

  7. Rapid cycling bipolar disorder: clinical characteristics and treatment options.

    Science.gov (United States)

    Coryell, William

    2005-01-01

    Approximately one of six patients who seek treatment for bipolar disorder present with a rapid cycling pattern. In comparison with other patients who have bipolar disorder, these individuals experience more affective morbidity in both the immediate and distant future and are more likely to experience recurrences despite treatment with lithium or anticonvulsants. Particular care should be given to distinguishing rapid cycling bipolar disorder from attention-deficit hyperactivity disorder in children or adolescents and from borderline personality disorder in adults. Perhaps four of five cases of rapid cycling resolve within a year, but the pattern may persist for many years in the remaining patients. As with bipolar disorder in general, depressive symptoms produce the most morbidity over time. Controlled studies have not established that antidepressants provoke switching or rapid cycling, but neither have they been shown consistently to have benefits in bipolar illness. Successful management will often require a sequence of trials with mood stabilizer drugs, beginning with lithium in treatment-naive patients. Efforts to minimise adverse effects, and the recognition that full benefits may not be apparent for several months, will make the premature abandonment of a potentially helpful treatment less likely. Placebo-controlled studies so far provide the most support for the use of lithium and lamotrigine as prophylactic agents. The combination of lithium and carbamazepine, valproate or lamotrigine for maintenance has some support from controlled studies, as does the adjunctive use of olanzapine.

  8. Association between psychological stress and menstrual cycle characteristics in perimenopausal women.

    Science.gov (United States)

    Barsom, Susannah Heyer; Mansfield, Phyllis Kernoff; Koch, Patricia Bartholow; Gierach, Gretchen; West, Sheila G

    2004-01-01

    In previous studies of the relationship between stress and menstrual cycles, stress has been found to be associated with longer cycles, to be associated with shorter cycles, and to have no association with cycle length. Some of the menstrual cycle changes that have been attributed to stress are similar to those experienced by women during perimenopause. In an effort to see whether an association between psychological stress and menstrual cycle characteristics can be detected in women approaching menopause, this study examines this relationship in perimenopausal women who are participants in the Tremin Research Program on Women's Health. The analyses used prospectively recorded bleeding data and retrospectively captured life-event data. A single-year cross-sectional analysis of data from 206 women shows no correlation between stress level, as measured by total number and severity of stressful life events, and cycle characteristics, including interval length, duration of bleed, and variability in both of these factors, nor are there significant differences in cycle characteristics between subgroups of women with different overall levels of stress. In analyzing stress levels and cycle characteristics across 2 years, however, women with marked increases in their level of stress (n = 30) are shown to have decreased length (-0.2 days/cycle) of menstrual cycle intervals and decreased duration of bleed (-0.1 day/cycle) compared with increases in these measures (+2.9 days/cycle for cycle interval; +0.3 days/cycle for duration of bleed) among women with no marked change in stress level (n = 103); t-tests indicate that these differences are significant (p < .05).

  9. Effect of thermal cycling on martensitic transformation and mechanical strengthening of stainless steels – A phase-field study

    DEFF Research Database (Denmark)

    Yeddu, Hemantha Kumar; Shaw, Brian A.; Somers, Marcel A. J.

    2017-01-01

    A 3D elastoplastic phase-field model is used to study the effect of thermal cycling on martensitic transformationas well as on mechanical strengthening of both austenite and martensite in stainless steel. The results show that with an increasing number of thermal cycles, martensite becomes more...

  10. Validation of a mathematical model of the bovine estrous cycle for cows with different estrous cycle characteristics.

    Science.gov (United States)

    Boer, H M T; Butler, S T; Stötzel, C; Te Pas, M F W; Veerkamp, R F; Woelders, H

    2017-11-01

    A recently developed mechanistic mathematical model of the bovine estrous cycle was parameterized to fit empirical data sets collected during one estrous cycle of 31 individual cows, with the main objective to further validate the model. The a priori criteria for validation were (1) the resulting model can simulate the measured data correctly (i.e. goodness of fit), and (2) this is achieved without needing extreme, probably non-physiological parameter values. We used a least squares optimization procedure to identify parameter configurations for the mathematical model to fit the empirical in vivo measurements of follicle and corpus luteum sizes, and the plasma concentrations of progesterone, estradiol, FSH and LH for each cow. The model was capable of accommodating normal variation in estrous cycle characteristics of individual cows. With the parameter sets estimated for the individual cows, the model behavior changed for 21 cows, with improved fit of the simulated output curves for 18 of these 21 cows. Moreover, the number of follicular waves was predicted correctly for 18 of the 25 two-wave and three-wave cows, without extreme parameter value changes. Estimation of specific parameters confirmed results of previous model simulations indicating that parameters involved in luteolytic signaling are very important for regulation of general estrous cycle characteristics, and are likely responsible for differences in estrous cycle characteristics between cows.

  11. Thermal enhancement of charge and discharge cycles for adsorbed natural gas storage

    KAUST Repository

    Rahman, Kazi Afzalur

    2011-07-01

    The usage of adsorbed natural gas (ANG) storage is hindered by the thermal management during the adsorption and desorption processes. An effective thermal enhancement is thus essential for the development of the ANG technology and the motivation for this study is the investigation of a gas storage system with internal thermal control. We employed a fin-tube type heat exchanger that is placed in a pressurized cylinder. A distributed-parameter model is used for the theoretical modeling and simulations are conducted at assorted charging and discharging conditions. These studies included the transient thermal behaviours of the elements within the ANG-charged cylinder and parameters such as pressure and temperature profiles of adsorbent have been obtained during charge and discharge cycles, and results are compared with a conventional compressed methane vessel. © 2011 Elsevier Ltd. All rights reserved.

  12. Thermal Stability of Hexamethyldisiloxane (MM for High-Temperature Organic Rankine Cycle (ORC

    Directory of Open Access Journals (Sweden)

    Markus Preißinger

    2016-03-01

    Full Text Available The design of efficient Organic Rankine Cycle (ORC units for the usage of industrial waste heat at high temperatures requires direct contact evaporators without intermediate thermal oil circuits. Therefore, the thermal stability of high-temperature working fluids gains importance. In this study, the thermal degradation of hexamethyldisiloxane (MM is investigated in an electrically heated tube. Qualitative results concerning remarks on degradation products as well as quantitative results like the annual degradation rate are presented. It is shown that MM is stable up to a temperature of 300 °C with annual degradation rates of less than 3.5%. Furthermore, the break of a silicon–carbon bond can be a main chemical reaction that influences the thermal degradation. Finally, it is discussed how the results may impact the future design of ORC units.

  13. Cell Cycle Characteristics of Crenarchaeota: Unity among Diversity▿

    OpenAIRE

    Lundgren, Magnus; Malandrin, Laurence; Eriksson, Stefan; Huber, Harald; Bernander, Rolf

    2008-01-01

    The hyperthermophilic archaea Acidianus hospitalis, Aeropyrum pernix, Pyrobaculum aerophilum, Pyrobaculum calidifontis, and Sulfolobus tokodaii representing three different orders in the phylum Crenarchaeota were analyzed by flow cytometry and combined phase-contrast and epifluorescence microscopy. The overall organization of the cell cycle was found to be similar in all species, with a short prereplicative period and a dominant postreplicative period that accounted for 64 to 77% of the gener...

  14. Ion exchange synthesis and thermal characteristics of some [ N ...

    Indian Academy of Sciences (India)

    using ion exchange method. These ionic liquids (ILs) were characterized using thermal methods, infrared spectroscopy and densitometry. Thermophysical properties such as density, coefficient of volume expansion, heat of fusion, heat capacity and thermal energy storage capacity were determined. Thermal conductivity of ...

  15. Ion exchange synthesis and thermal characteristics of some [N

    Indian Academy of Sciences (India)

    ... conductivity of the samples was determined both in solid and liquid phases. Owing to high values of thermal energy storage capacity coupled with handsome liquid phase thermal conductivity, ILs under investigation were recommended as materials for thermal energy storage (TES) as well as heat transfer applications.

  16. A Study on thermal-hydraulic characteristics of the coolant materials for the transmutation reactor

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Chang Hyun; You, Young Woo; Cho, Jae Seon; Kim, Ju Youl; Kim, Do Hyoung; Kim, Yoon Ik; Yang, Hui Chang [Seoul National University, Taejon (Korea)

    1998-03-01

    The objective of this study is to provide the direction of transmutation reactor design in terms of thermal hydraulics especially through the analysis of thermal hydraulic characteristics of various candidate materials for the transmutation reactor coolant. In this study, the characteristics of coolant materials used in current nuclear power plants and candidate materials for transmutation reactor are analyzed and compared. To evaluate the thermal hydraulic characteristics, the preliminary thermal-hydraulic calculation is performed for the candidate coolant materials of transmutation reactor. An analysis of thermal-hydraulic characteristics of transmutation reactor. An analysis of thermal-hydraulic characteristics of Sodium, Lead, Lead-Bismuth, and Lead-Lithium among the liquid metals considered as the coolant of transmutation reactor is performed by using computational fluid dynamics code FLUENT, and SIMPLER algorithm. (author). 50 refs., 40 figs., 30 tabs.

  17. Evaluations of thermocline and half cycle figure of merit of a thermal energy storage tank

    Directory of Open Access Journals (Sweden)

    Abd Majid Mohd Amin

    2017-01-01

    Full Text Available Two main criteria that are commonly used to evaluate thermal energy storage systems are thermocline thickness and half cycle figure of merit. For the thermocline thickness, the preference is to achieve as thin as possible the thermocline thickness. While the preference for half cycle figure of merit is to achieve the value of greater than 90 per cent. These two criteria were used to evaluate a thermal storage system at University Teknologi PETRONAS district cooling plant. The capacity of the thermal energy storage tank of the plant is 10,000 RTh. Operating data was used for the evaluation. The values of evaluated thermocline thickness ranges from 2.248 meters to 5.445 meters with an average of 3.251 meters. These values are very much higher in comparison to findings of other studies. One possible reason is due to higher flow rates. For the half cycle figure of merit the evaluated values ranges from 0.9469 to 0.9847, with the average of 0.9698, which are within the acceptable range. For future work a model should be developed which could automatically evaluate both the thermocline thickness and half cycle figure of merit. This would enable both of these parameters to be continuously evaluated.

  18. Thermally Induced Ultra High Cycle Fatigue of Copper Alloys of the High Gradient Accelerating Structures

    CERN Document Server

    Heikkinen, Samuli; Wuensch, Walter

    2010-01-01

    In order to keep the overall length of the compact linear collider (CLIC), currently being studied at the European Organization for Nuclear Research (CERN), within reasonable limits, i.e. less than 50 km, an accelerating gradient above 100 MV/m is required. This imposes considerable demands on the materials of the accelerating structures. The internal surfaces of these core components of a linear accelerator are exposed to pulsed radio frequency (RF) currents resulting in cyclic thermal stresses expected to cause surface damage by fatigue. The designed lifetime of CLIC is 20 years, which results in a number of thermal stress cycles of the order of 2.33•1010. Since no fatigue data existed in the literature for CLIC parameter space, a set of three complementary experiments were initiated: ultra high cycle mechanical fatigue by ultrasound, low cycle fatigue by pulsed laser irradiation and low cycle thermal fatigue by high power microwaves, each test representing a subset of the original problem. High conductiv...

  19. Weldability examination of ASTM A 240 S41500 martensitic stainless steel by thermal cycles simulation testings

    Directory of Open Access Journals (Sweden)

    Alberto Velázquez-del Rosario

    2015-07-01

    Full Text Available The weldability assets of ASTM A 240 S41500 (ASTM A 240/A 240M martensitic stainless steel are presented through the study of the effects of single and double thermal weld cycles on mechanical properties and microstructure of base metal (BM and the artificial heat affected zone (HAZ created by thermal weld simulations. For single cycles, separate peak temperatures of 1000 ºC/12 s and 1350 ºC/12 s (cooling times: 12 s in both cases were evaluated, whilst two combinations of peak temperatures: (1350 ºC/5 s + 1000 ºC/5 s ºC and (1350 ºC/12 s + 1000 ºC/12 s ºC (cooling times: 5 s and 12 s, were applied for double cycles. Post weld heat treatment (PWHT with short and long holding times were applied and Vickers hardness, impact toughness and metallographic examinations were used in order to assess mechanical and metallographic properties in the as-simulated (no heat treated and postweld heat treated conditions. Best properties of the welded joint for double thermal weld cycles with long holding times were reached, which reveals the good weldability and applicability of the tested material in post weld heat treated conditions.

  20. Characteristics of large thermal energy storage systems in Poland

    Science.gov (United States)

    Zwierzchowski, Ryszard

    2017-11-01

    In District Heating Systems (DHS) there are significant fluctuations in demand for heat by consumers during both the heating and the summer seasons. These variations are considered primarily in the 24-hour time horizon. These problems are aggravated further if the DHS is supplied by a CHP plant, because fluctuations in heat demand adversely affect to a significant degree the stable production of electricity at high overall efficiency. Therefore, introducing Thermal Energy Storage (TES) would be highly recommended on these grounds alone. The characteristics of Large (i.e. over 10 000 m3) TES in operation in Poland are presented. Information is given regarding new projects (currently in design or construction) that apply TES technology in DHS in Poland. The paper looks at the methodology used in Poland to select the TES system for a particular DHS, i.e., procedure for calculating capacity of the TES tank and the system to prevent water stored in the tank from absorbing oxygen from atmospheric air. Implementation of TES in DHS is treated as a recommended technology in the Polish District Heating sector. This technology offers great opportunities to improve the operating conditions of DHS, cutting energy production costs and emissions of pollutants to the atmosphere.

  1. Characteristics of large thermal energy storage systems in Poland

    Directory of Open Access Journals (Sweden)

    Zwierzchowski Ryszard

    2017-01-01

    Full Text Available In District Heating Systems (DHS there are significant fluctuations in demand for heat by consumers during both the heating and the summer seasons. These variations are considered primarily in the 24-hour time horizon. These problems are aggravated further if the DHS is supplied by a CHP plant, because fluctuations in heat demand adversely affect to a significant degree the stable production of electricity at high overall efficiency. Therefore, introducing Thermal Energy Storage (TES would be highly recommended on these grounds alone. The characteristics of Large (i.e. over 10 000 m3 TES in operation in Poland are presented. Information is given regarding new projects (currently in design or construction that apply TES technology in DHS in Poland. The paper looks at the methodology used in Poland to select the TES system for a particular DHS, i.e., procedure for calculating capacity of the TES tank and the system to prevent water stored in the tank from absorbing oxygen from atmospheric air. Implementation of TES in DHS is treated as a recommended technology in the Polish District Heating sector. This technology offers great opportunities to improve the operating conditions of DHS, cutting energy production costs and emissions of pollutants to the atmosphere.

  2. Developing a thermal characteristic index for lithology identification using thermal infrared remote sensing data

    Science.gov (United States)

    Wei, Jiali; Liu, Xiangnan; Ding, Chao; Liu, Meiling; Jin, Ming; Li, Dongdong

    2017-01-01

    In remote sensing petrology fields, studies have mainly concentrated on spectroscopy remote sensing research, and methods to identify minerals and rocks are mainly based on the analysis and enhancement of spectral features. Few studies have reported the application of thermodynamics for lithology identification. This paper aims to establish a thermal characteristic index (TCI) to explore rock thermal behavior responding to defined environmental systems. The study area is located in the northern Qinghai Province, China, on the northern edge of the Qinghai-Tibet Plateau, where mafic-ultramafic rock, quartz-rich rock, alkali granite rock and carbonate rock are well exposed; the pixel samples of these rocks and vegetation were obtained based on relevant indices and geological maps. The scatter plots of TCI indicate that mafic-ultramafic rock and quartz-rich rock can be well extracted from other surface objects when interference from vegetation is lower. On account of the complexity of environmental systems, three periods of TCI were used to construct a three-dimensional scatter plot, named the multi-temporal thermal feature space (MTTFS) model. Then, the Bayes discriminant analysis algorithm was applied to the MTTFS model to extract rocks quantitatively. The classification accuracy of mafic-ultramafic rock is more than 75% in both training data and test data, which suggests TCI can act as a sensitive indicator to distinguish rocks and the MTTFS model can accurately extract mafic-ultramafic rock from other surface objects. We deduce that the use of thermodynamics is promising in lithology identification when an effective index is constructed and an appropriated model is selected.

  3. Fundamental-frequency and load-varying thermal cycles effects on lifetime estimation of DFIG power converter

    DEFF Research Database (Denmark)

    Zhang, Guanguan; Zhou, Dao; Yang, Jian

    2017-01-01

    In respect to a Doubly-Fed Induction Generator (DFIG) system, its corresponding time scale varies from microsecond level of power semiconductor switching to second level of the mechanical response. In order to map annual thermal profile of the power semiconductors, different approaches have been...... adopted to handle the fundamental-frequency thermal cycles and load-varying thermal cycles. Their effects on lifetime estimation of the power device in the Back-to-Back (BTB) power converter are evaluated....

  4. Research on influence of different cover to the characteristic of FBG reflectance spectrum in vacuum thermal environment

    Science.gov (United States)

    Pei, Yifei; Zhang, Jingchuan; Zhang, Luosha; Liu, Yang; Zhang, Lina; Chen, Shiyu

    2018-01-01

    To satisfy the application of fiber grating sensor technology in high vacuum thermal environment, two different kinds of sleeve compactly single model fiber covered by acrylate and polyimide are researched. Influence of the cover to the characteristic of FBG reflectance spectrum in high vacuum thermal environment is analyzed and verified. First, transmission characteristic of single model fiber in high vacuum thermal environment is analyzed by solve the equation of heat conduction. Then, experimental program of influence on FBG reflection spectrum characteristics is designed and a hardware-in-the-loop detection platform is set up. Finally, the influence of temperature and vacuum on the reflection peak power of FBG in different coating single-mode transmission fiber under high vacuum thermal environment is studied and verified. Experimental results indicate that: when vacuum varied from normal pressure to 10-4Pa level and then return to normal pressure, temperature of two different coating single-mode transmission fiber dropped to -196 ° from room temperature and then returned to room temperature, after 224 hours, the peak power of the FBG reflectance spectrum did not change. It provided the theoretical and experimental basis for the application of optical fiber sensing technology in high vacuum (pressure about 10-4Pa level) and thermal environment (-196 ° 25 ° temperature cycle) .

  5. Theoretical study of thermally driven heat pumps based on double organic rankine cycle

    OpenAIRE

    Demierre, Jonathan; Favrat, Daniel

    2013-01-01

    Part of: Thermally driven heat pumps for heating and cooling. – Ed.: Annett Kühn – Berlin: Universitätsverlag der TU Berlin, 2013 ISBN 978-3-7983-2686-6 (print) ISBN 978-3-7983-2596-8 (online) urn:nbn:de:kobv:83-opus4-39458 [http://nbn-resolving.de/urn:nbn:de:kobv:83-opus4-39458] This study deals with a type of thermally driven heat pumps that consists of a reverse Rankine heat pump cycle, the compressor of which is driven by the turbine of a supercritical Organi...

  6. EXPERIMENTAL STUDY OF THE THERMAL BEHAVIOUR OF HYDROGEN TANKS DURING HYDROGEN CYCLING

    OpenAIRE

    DE MIGUEL ECHEVARRIA NEREA; Acosta Iborra, Beatriz; Moretto, Pietro; HARSKAMP Frederik; BONATO CHRISTIAN

    2013-01-01

    The thermal behaviour of several commercial hydrogen tanks has been studied during high pressure (70-84 MPa) hydrogen cycling. The temperature of the gas at different points inside the tank, the temperature at the bosses and the tank outer wall temperature have been measured under different filling and emptying conditions. From the experimental results, the effect of the filling rate (1.5-4 g/s) and the influence of the liner material in the thermal behaviour of the hydrogen tanks have been e...

  7. Electro-optical characteristics of indium tin oxide (ITO) films: effect of thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, D.V.; Salehi, A.; Aliyu, Y.H.; Bunce, R.W. [University of Wales College of Cardiff (United Kingdom). School of Electrical, Electronics and System Engineering

    1996-02-01

    The effect of thermal annealing on the electrical and optical characteristics of ITO films prepared by reactive sputtering and thermal evaporation have been studied. The effect of the thermal annealing is to improve the conductivity and the optical transmission in the shorter wavelength region. The conductivity of the films increases with annealing temperature, this behaviour is associated with grain growth in the film. (author)

  8. Thermal analysis of heat and power plant with high temperature reactor and intermediate steam cycle

    Directory of Open Access Journals (Sweden)

    Fic Adam

    2015-03-01

    Full Text Available Thermal analysis of a heat and power plant with a high temperature gas cooled nuclear reactor is presented. The main aim of the considered system is to supply a technological process with the heat at suitably high temperature level. The considered unit is also used to produce electricity. The high temperature helium cooled nuclear reactor is the primary heat source in the system, which consists of: the reactor cooling cycle, the steam cycle and the gas heat pump cycle. Helium used as a carrier in the first cycle (classic Brayton cycle, which includes the reactor, delivers heat in a steam generator to produce superheated steam with required parameters of the intermediate cycle. The intermediate cycle is provided to transport energy from the reactor installation to the process installation requiring a high temperature heat. The distance between reactor and the process installation is assumed short and negligable, or alternatively equal to 1 km in the analysis. The system is also equipped with a high temperature argon heat pump to obtain the temperature level of a heat carrier required by a high temperature process. Thus, the steam of the intermediate cycle supplies a lower heat exchanger of the heat pump, a process heat exchanger at the medium temperature level and a classical steam turbine system (Rankine cycle. The main purpose of the research was to evaluate the effectiveness of the system considered and to assess whether such a three cycle cogeneration system is reasonable. Multivariant calculations have been carried out employing the developed mathematical model. The results have been presented in a form of the energy efficiency and exergy efficiency of the system as a function of the temperature drop in the high temperature process heat exchanger and the reactor pressure.

  9. Thermal analysis of heat and power plant with high temperature reactor and intermediate steam cycle

    Science.gov (United States)

    Fic, Adam; Składzień, Jan; Gabriel, Michał

    2015-03-01

    Thermal analysis of a heat and power plant with a high temperature gas cooled nuclear reactor is presented. The main aim of the considered system is to supply a technological process with the heat at suitably high temperature level. The considered unit is also used to produce electricity. The high temperature helium cooled nuclear reactor is the primary heat source in the system, which consists of: the reactor cooling cycle, the steam cycle and the gas heat pump cycle. Helium used as a carrier in the first cycle (classic Brayton cycle), which includes the reactor, delivers heat in a steam generator to produce superheated steam with required parameters of the intermediate cycle. The intermediate cycle is provided to transport energy from the reactor installation to the process installation requiring a high temperature heat. The distance between reactor and the process installation is assumed short and negligable, or alternatively equal to 1 km in the analysis. The system is also equipped with a high temperature argon heat pump to obtain the temperature level of a heat carrier required by a high temperature process. Thus, the steam of the intermediate cycle supplies a lower heat exchanger of the heat pump, a process heat exchanger at the medium temperature level and a classical steam turbine system (Rankine cycle). The main purpose of the research was to evaluate the effectiveness of the system considered and to assess whether such a three cycle cogeneration system is reasonable. Multivariant calculations have been carried out employing the developed mathematical model. The results have been presented in a form of the energy efficiency and exergy efficiency of the system as a function of the temperature drop in the high temperature process heat exchanger and the reactor pressure.

  10. Effect of prolonged thermal cycling on microleakage around Class V cavities restored with glass-ceramic inserts with different coefficients of thermal expansion: an in vitro study.

    Science.gov (United States)

    Santini, Ario; Ivanovic, Vladimir; Tan, Chuei Luan; Ibbetson, Richard

    2006-10-01

    The purpose of this in vitro study was to evaluate microleakage around Class V glass-ceramic restorations of different coefficients of thermal expansion after prolonged thermal cycling. One hundred and twenty noncarious extracted human premolars (patient age range 12-20 years) were randomly assigned to three groups. Standard Class V preparations were cut in the buccal surface using customised Cerana burs, size no. 3. Glass-ceramic inserts from two manufacturers (Cerana, Nordiska Dental AB, Helsingborg, Sweden; Beta-Quartz, Hager & Werken GmbH, Duisburg, Germany) were used to restore the cavities and were luted with a hybrid, high-viscous composite (Tetric Ceram, Ivoclar Vivadent, Schaan, Liechtenstein) and a bonding agent (Excite, Ivoclar Vivadent, Schaan, Liechtenstein). A control group, without inserts, was bulk-filled with the same composite used as the luting agent. In accordance with American Dental Association guidelines, half of the preparation was in enamel, half in dentine/cementum and had a mesio-distal width of 3 mm, an occluso-gingival height of 3 mm, and a depth of 2 mm. All margins had butt joints. Sixty teeth, selected at random, were not thermal cycled; the remaining 60 teeth were thermal cycled 4000 times between water baths held at 5 degrees C and 55 degrees C and the specimens prepared and examined for microleakage using 2.0% Procion Red (ICI, Slough, UK) dye, buffered at pH7, as a marker. The results were analysed using the Kruskal-Wallis test (ANOVA) at a 95% significance level. At the occlusal margins there was no significant difference in microleakage between the three groups (P>0.5) without thermal cycling. After thermal cycling, microleakage at the occlusal margins was significantly less around cavities restored with Cerana glass-ceramic inserts versus Beta-Quartz and Tetric Ceram (Pmicroleakge between the groups before thermal cycling (P>0.5). After thermal cycling, there was significantly less microleakage between Cerana inserts and

  11. Cell cycle characteristics of crenarchaeota: unity among diversity.

    Science.gov (United States)

    Lundgren, Magnus; Malandrin, Laurence; Eriksson, Stefan; Huber, Harald; Bernander, Rolf

    2008-08-01

    The hyperthermophilic archaea Acidianus hospitalis, Aeropyrum pernix, Pyrobaculum aerophilum, Pyrobaculum calidifontis, and Sulfolobus tokodaii representing three different orders in the phylum Crenarchaeota were analyzed by flow cytometry and combined phase-contrast and epifluorescence microscopy. The overall organization of the cell cycle was found to be similar in all species, with a short prereplicative period and a dominant postreplicative period that accounted for 64 to 77% of the generation time. Thus, in all Crenarchaeota analyzed to date, cell division and initiation of chromosome replication occur in close succession, and a long time interval separates termination of replication from cell division. In Pyrobaculum, chromosome segregation overlapped with or closely followed DNA replication, and further genome separation appeared to occur concomitant with cellular growth. Cell division in P. aerophilum took place without visible constriction.

  12. Cell Cycle Characteristics of Crenarchaeota: Unity among Diversity▿

    Science.gov (United States)

    Lundgren, Magnus; Malandrin, Laurence; Eriksson, Stefan; Huber, Harald; Bernander, Rolf

    2008-01-01

    The hyperthermophilic archaea Acidianus hospitalis, Aeropyrum pernix, Pyrobaculum aerophilum, Pyrobaculum calidifontis, and Sulfolobus tokodaii representing three different orders in the phylum Crenarchaeota were analyzed by flow cytometry and combined phase-contrast and epifluorescence microscopy. The overall organization of the cell cycle was found to be similar in all species, with a short prereplicative period and a dominant postreplicative period that accounted for 64 to 77% of the generation time. Thus, in all Crenarchaeota analyzed to date, cell division and initiation of chromosome replication occur in close succession, and a long time interval separates termination of replication from cell division. In Pyrobaculum, chromosome segregation overlapped with or closely followed DNA replication, and further genome separation appeared to occur concomitant with cellular growth. Cell division in P. aerophilum took place without visible constriction. PMID:18502873

  13. Radiation and Thermal Cycling Effects on EPC1001 Gallium Nitride Power Transistors

    Science.gov (United States)

    Patterson, Richard L.; Scheick, Leif Z.; Lauenstein, Jean M.; Casey, Megan C.; Hammoud, Ahmad

    2012-01-01

    Electronics designed for use in NASA space missions are required to work efficiently and reliably under harsh environment conditions. These include radiation, extreme temperatures, and thermal cycling, to name a few. Information pertaining to performance of electronic parts and systems under hostile environments is very scarce, especially for new devices. Such data is very critical so that proper design is implemented in order to ensure mission success and to mitigate risks associated with exposure of on-board systems to the operational environment. In this work, newly-developed enhancement-mode field effect transistors (FET) based on gallium nitride (GaN) technology were exposed to various particles of ionizing radiation and to long-term thermal cycling over a wide temperature range. Data obtained on control (un-irradiated) and irradiated samples of these power transistors are presented and the results are discussed.

  14. The Effect of Menstrual Cycle on Nasal Resonance Characteristics in Females

    Science.gov (United States)

    Kumar, Suman; Basu, Shriya; Sinha, Anisha; Chatterjee, Indranil

    2012-01-01

    The purpose of this study was to analyze resonance characteristics (nasality and nasalance values) during the menstrual cycle. Previous studies indicate changes in voice quality and nasal mucosa due to temporary falling estrogen levels in human females during their menstrual cycle. The present study compared the nasality and "nasalance scores"…

  15. Examining Associations of Environmental Characteristics with Recreational Cycling Behaviour by Street-Level Strava Data

    OpenAIRE

    Sun, Yeran; Du, Yunyan; Wang, Yu; Zhuang, Liyuan

    2017-01-01

    Policymakers pay much attention to effectively increasing frequency of people’s cycling in\\ud the context of developing sustainable and green cities. Investigating associations of environmental characteristics and cycling behaviour could offer implications for changing urban infrastructure aiming at encouraging active travel. However, earlier examinations of associations between environmental characteristics and active travel behaviour are limited by low spatial granularity and coverage of tr...

  16. Microstructural characterization and thermal cycling reliability of solders under isothermal aging and electrical current

    Science.gov (United States)

    Chauhan, Preeti Singh

    Solder joints on printed circuit boards provide electrical and mechanical connections between electronic devices and metallized patterns on boards. These solder joints are often the cause of failure in electronic packages. Solders age under storage and operational life conditions, which can include temperature, mechanical loads, and electrical current. Aging occurring at a constant temperature is called isothermal aging. Isothermal aging leads to coarsening of the bulk microstructure and increased interfacial intermetallic compounds at the solder-pad interface. The coarsening of the solder bulk degrades the creep properties of solders, whereas the voiding and brittleness of interfacial intermetallic compounds leads to mechanical weakness of the solder joint. Industry guidelines on solder interconnect reliability test methods recommend preconditioning the solder assemblies by isothermal aging before conducting reliability tests. The guidelines assume that isothermal aging simulates a "reasonable use period," but do not relate the isothermal aging levels with specific use conditions. Studies on the effect of isothermal aging on the thermal cycling reliability of tin-lead and tin-silver-copper solders are limited in scope, and results have been contradictory. The effect of electrical current on solder joints has been has mostly focused on current densities above 104A/cm2 with high ambient temperature (≥100oC), where electromigration, thermomigration, and Joule heating are the dominant failure mechanisms. The effect of current density below 104A/cm2 on temperature cycling fatigue of solders has not been established. This research provides the relation between isothermal aging and the thermal cycling reliability of select Sn-based solders. The Sn-based solders with 3%, 1%, and 0% silver content that have replaced tin-lead are studied and compared against tin-lead solder. The activation energy and growth exponents of the Arrhenius model for the intermetallic growth in

  17. Thermal Cycling and High-Temperature Corrosion Tests of Rare Earth Silicate Environmental Barrier Coatings

    Science.gov (United States)

    Darthout, Émilien; Gitzhofer, François

    2017-12-01

    Lutetium and yttrium silicates, enriched with an additional secondary zirconia phase, environmental barrier coatings were synthesized by the solution precursor plasma spraying process on silicon carbide substrates. A custom-made oven was designed for thermal cycling and water vapor corrosion testing. The oven can test four specimens simultaneously and allows to evaluate environmental barrier performances under similar corrosion kinetics compared to turbine engines. Coatings structural evolution has been observed by SEM on the polished cross sections, and phase composition has been analyzed by XRD. All coatings have been thermally cycled between 1300 °C and the ambient temperature, without spallation, due to their porosity and the presence of additional secondary phase which increases the thermal cycling resistance. During water vapor exposure at 1200 °C, rare earth disilicates showed a good stability, which is contradictory with the literature, due to impurities—such as Si- and Al-hydroxides—in the water vapor jets. The presence of vertical cracks allowed the water vapor to reach the substrate and then to corrode it. It has been observed that thin vertical cracks induced some spallation after 24 h of corrosion.

  18. Thermal Hydraulic Analysis of 3 MW TRIGA Research Reactor of Bangladesh Considering Different Cycles of Burnup

    Directory of Open Access Journals (Sweden)

    M.H. Altaf

    2014-12-01

    Full Text Available Burnup dependent steady state thermal hydraulic analysis of TRIGA Mark-II research reactor has been carried out utilizing coupled point kinetics, neutronics and thermal hydraulics code EUREKA-2/RR. From the previous calculations of neutronics parameters including percentage burnup of individual fuel elements performed so far for 700 MWD burnt core of TRIGA reactor showed that the fuel rod predicted as hottest at the beginning of cycle (fresh core was found to remain as the hottest until 200 MWD of burn, but, with the progress of core burn, the hottest rod was found to be shifted and another rod in the core became the hottest. The present study intends to evaluate the thermal hydraulic parameters of these hottest fuel rods at different cycles of burnup, from beginning to 700 MWD core burnt considering reactor operates under steady state condition. Peak fuel centerline temperature, maximum cladding and coolant temperatures of the hottest channels were calculated. It revealed that maximum temperature reported for fuel clad and fuel centerline found to lie below their melting points which indicate that there is no chance of burnout on the fuel cladding surface and no blister in the fuel meat throughout the considered cycles of core burnt.

  19. Thermal Cycling and Isothermal Deformation Response of Polycrystalline NiTi: Simulations vs. Experiment

    Science.gov (United States)

    Manchiraju, Sivom; Gaydosh, Darrell; Benafan, Othmane; Noebe, Ronald; Vaidyanathan, Raj; Anderson, Peter M.

    2011-01-01

    A recent microstructure-based FEM model that couples crystal-based plasticity, the B2 MB190 phase transformation and anisotropic elasticity at the grain scale is calibrated to recent data for polycrystalline NiTi (49.9 at.% Ni). Inputs include anisotropic elastic properties, texture and differential scanning calorimetry data, as well as a subset of recent isothermal deformation and load-biased thermal cycling data. The model is assessed against additional experimental data. Several experimental trends are captured - in particular, the transformation strain during thermal cycling monotonically increases and reaches a peak with increasing bias stress. This is achieved, in part, by modifying the martensite hardening matrix proposed by Patoor et al. [Patoor E, Eberhardt A, Berveiller M. J Phys IV 1996;6:277]. Some experimental trends are underestimated - in particular, the ratcheting of macrostrain during thermal cycling. This may reflect a model limitation that transformation-plasticity coupling is captured on a coarse (grain) scale but not on a fine (martensitic plate) scale.

  20. Thermal Cycling and High-Temperature Corrosion Tests of Rare Earth Silicate Environmental Barrier Coatings

    Science.gov (United States)

    Darthout, Émilien; Gitzhofer, François

    2017-09-01

    Lutetium and yttrium silicates, enriched with an additional secondary zirconia phase, environmental barrier coatings were synthesized by the solution precursor plasma spraying process on silicon carbide substrates. A custom-made oven was designed for thermal cycling and water vapor corrosion testing. The oven can test four specimens simultaneously and allows to evaluate environmental barrier performances under similar corrosion kinetics compared to turbine engines. Coatings structural evolution has been observed by SEM on the polished cross sections, and phase composition has been analyzed by XRD. All coatings have been thermally cycled between 1300 °C and the ambient temperature, without spallation, due to their porosity and the presence of additional secondary phase which increases the thermal cycling resistance. During water vapor exposure at 1200 °C, rare earth disilicates showed a good stability, which is contradictory with the literature, due to impurities—such as Si- and Al-hydroxides—in the water vapor jets. The presence of vertical cracks allowed the water vapor to reach the substrate and then to corrode it. It has been observed that thin vertical cracks induced some spallation after 24 h of corrosion.

  1. Performance characteristic of a Stirling refrigeration cycle in micro/nano scale

    Science.gov (United States)

    Nie, Wenjie; He, Jizhou; Du, Jianqiang

    2009-02-01

    The aim of the paper is to present the performance characteristics of a Stirling refrigeration cycle in micro/nano scale, in which the working substance of cycle is an ideal Maxwellian gas. Due to the quantum boundary effect on the gas particles confined in the finite domain, the cycle no longer possesses the condition of perfect regeneration. The inherent regenerative losses, the refrigeration heat and coefficient of performance (COP) of the cycle are derived. It is found that, for the micro/nano scaled Stirling refrigeration cycle devices, the refrigeration heat and COP of cycle all depend on the surface area of the system (boundary of cycle) besides the temperature of the heat reservoirs, the volume of system and other parameters, while for the macro scaled refrigeration cycle devices, the refrigeration heat and COP of cycle are independent of the surface area of the system. Variations of the refrigeration heat ratio rR and the COP ratio rε with the temperature ratio τ and volume ratio rV for the different surface area ratio rA are examined, which reveals the influence of the boundary of cycle on the performance of a micro/nano scaled Stirling refrigeration cycle. The results are useful for designing of a micro/nano scaled Stirling cycle device and may conduce to confirming experimentally the quantum boundary effect in the micro/nano scaled devices.

  2. Thermal and chemical characteristics of hot water springs in the ...

    African Journals Online (AJOL)

    The temperatures at source vary from 30°C to 67.5°C. The springs are associated with faults and impermeable dykes and are assumed to be of meteoric origin. The mineral composition of the ... the ultimate use of the thermal springs. Keywords: thermal springs, South Africa, macro and micro-elements, geological controls ...

  3. Measured Thermal and Fast Neutron Fluence Rates for ATF-1 Holders During ATR Cycle 157D

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Larry Don [Idaho National Lab. (INL), Idaho Falls, ID (United States); Miller, David Torbet [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-03-01

    This report contains the thermal (2200 m/s) and fast (E>1MeV) neutron fluence rate data for the ATF-1 holders located in core for ATR Cycle 157D which were measured by the Radiation Measurements Laboratory (RML) as requested by the Power Reactor Programs (ATR Experiments) Radiation Measurements Work Order. This report contains measurements of the fluence rates corresponding to the particular elevations relative to the 80-ft. core elevation. The data in this report consist of (1) a table of the ATR power history and distribution, (2) a hard copy listing of all thermal and fast neutron fluence rates, and (3) plots of both the thermal and fast neutron fluence rates. The fluence rates reported are for the average power levels given in the table of power history and distribution.

  4. Reactive power influence on the thermal cycling of multi-MW wind power inverter

    DEFF Research Database (Denmark)

    Ma, Ke; Liserre, Marco; Blaabjerg, Frede

    2013-01-01

    In this paper the reactive power influence on the thermal cycling of power devices in grid-connected inverter for 10 MW wind turbines is investigated. Restrained by the grid codes, the allowable reactive power ranges in relation to amplitude and phase angle of the load current for a single...... converter system are first presented at different wind speeds. Furthermore, the interaction between paralleled converter systems in a wind park is also considered and analyzed. By controlling the reactive power circulated among paralleled converters, a new concept is then proposed to stabilize the thermal...... fluctuation of the power devices during wind gusts. It is concluded that the reactive power may change the thermal distribution of power devices. By properly controlling the reactive power, it is possible to achieve a more stable junction temperature in the power devices during the fluctuation of wind speed...

  5. Reactive power influence on the thermal cycling of multi-MW wind power inverter

    DEFF Research Database (Denmark)

    Ma, Ke; Liserre, Marco; Blaabjerg, Frede

    2012-01-01

    In this paper the reactive power influence on the thermal cycling of power devices in grid-connected inverter for 10 MW wind turbines is investigated. Restrained by the grid codes, the allowable reactive power ranges in relation to amplitude and phase angle of the load current for a single...... converter system are first presented at different wind speeds. Furthermore, the interaction between paralleled converter systems in a wind park is also considered and analyzed. By controlling the reactive power circulated among paralleled converters, a new concept is then proposed to stabilize the thermal...... fluctuation of the power devices during wind gusts. It is concluded that the reactive power may change the thermal distribution of power devices. By properly controlling the reactive power, it is possible to achieve a more stable junction temperature in the power devices during the fluctuation of wind speed...

  6. Technical and economic feasibility of a Thermal Gradient Utilization Cycle (TGUC) power plant

    Science.gov (United States)

    Raiji, A. M.; Renfroe, D. A.; Lalk, T. R.

    Power is generated by exploiting the natural atmospheric temperature gradient. A low grade energy source is used to vaporize a fluid which rises in a pipe to a higher elevation where it is condensed. The cycle is completed by passing the condensed liquid through a turbine as it returns to the lower elevation. A digital computer model was developed and used to simulate the operation of the cycle and to conduct a parameteric study. Life cycle cost analysis and energy analyses were conducted for the specific case of a TGUC using the ambient air at the lower elevation as an energy source. Although the cycle has a low thermal efficiency and is site specific, it is technically feasible. Variations in mass flow rate of the working fluid and elevation were found to affect the cycle power output to a large extent. The investment cost of a hypothetical 10 megawatt TGUC power plant was determined to be $3,080 per kilowatt, with life cycle busbar costs of electricity ranging from 47 to 55 Mills per kilowatt hour depending on the method of financing.

  7. Thermal Cycling Behavior of Thermal Barrier Coatings with MCrAlY Bond Coat Irradiated by High-Current Pulsed Electron Beam.

    Science.gov (United States)

    Cai, Jie; Lv, Peng; Guan, Qingfeng; Xu, Xiaojing; Lu, Jinzhong; Wang, Zhiping; Han, Zhiyong

    2016-11-30

    Microstructural modifications of a thermally sprayed MCrAlY bond coat subjected to high-current pulsed electron beam (HCPEB) and their relationships with thermal cycling behavior of thermal barrier coatings (TBCs) were investigated. Microstructural observations revealed that the rough surface of air plasma spraying (APS) samples was significantly remelted and replaced by many interconnected bulged nodules after HCPEB irradiation. Meanwhile, the parallel columnar grains with growth direction perpendicular to the coating surface were observed inside these bulged nodules. Substantial Y-rich Al2O3 bubbles and varieties of nanocrystallines were distributed evenly on the top of the modified layer. A physical model was proposed to describe the evaporation-condensation mechanism taking place at the irradiated surface for generating such surface morphologies. The results of thermal cycling test showed that HCPEB-TBCs presented higher thermal cycling resistance, the spalling area of which after 200 cycles accounted for only 1% of its total area, while it was about 34% for APS-TBCs. The resulting failure mode, i.e., in particular, a mixed delamination crack path, was shown and discussed. The irradiated effects including compact remelted surface, abundant nanoparticles, refined columnar grains, Y-rich alumina bubbles, and deformation structures contributed to the formation of a stable, continuous, slow-growing, and uniform thermally grown oxide with strong adherent ability. It appeared to be responsible for releasing stress and changing the cracking paths, and ultimately greatly improving the thermal cycling behavior of HCPEB-TBCs.

  8. Thermal Modelling Analysis of Spiral Wound Supercapacitor under Constant-Current Cycling

    Science.gov (United States)

    Wang, Kai; Li, Liwei; Yin, Huaixian; Zhang, Tiezhu; Wan, Wubo

    2015-01-01

    A three-dimensional modelling approach is used to study the effects of operating and ambient conditions on the thermal behaviour of the spiral wound supercapacitor. The transient temperature distribution during cycling is obtained by using the finite element method with an implicit predictor-multicorrector algorithm. At the constant current of 2A, the results show that the maximum temperature appears in core area. After 5 cycles, the maximum temperature is 34.5°C, while in steady state, it’s up to 42.5°C. This paper further studies the relationship between the maximum temperature and charge-discharge current. The maximum temperature will be more than 60°C after 5 cycles at the current of 4A, and cooling measurements should be taken at that time. It can provide thoughts on inner temperature field distribution and structure design of the spiral wound supercapacitor in working process. PMID:26444687

  9. Thermal Modelling Analysis of Spiral Wound Supercapacitor under Constant-Current Cycling.

    Science.gov (United States)

    Wang, Kai; Li, Liwei; Yin, Huaixian; Zhang, Tiezhu; Wan, Wubo

    2015-01-01

    A three-dimensional modelling approach is used to study the effects of operating and ambient conditions on the thermal behaviour of the spiral wound supercapacitor. The transient temperature distribution during cycling is obtained by using the finite element method with an implicit predictor-multicorrector algorithm. At the constant current of 2A, the results show that the maximum temperature appears in core area. After 5 cycles, the maximum temperature is 34.5°C, while in steady state, it's up to 42.5°C. This paper further studies the relationship between the maximum temperature and charge-discharge current. The maximum temperature will be more than 60°C after 5 cycles at the current of 4A, and cooling measurements should be taken at that time. It can provide thoughts on inner temperature field distribution and structure design of the spiral wound supercapacitor in working process.

  10. Analysis of thermal cycles and microstructure of heat affected zone for a low alloy carbon steel pipe under multipass weld

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Tae Woan; Ha, Joon Wook; Kim, Dong Jin; Kim, Jeong Tae [Doosan Heavy Industries and Construction Co., Ltd., Changwon (Korea, Republic of)

    2002-03-01

    The purpose of this study is to analyze thermal cycles and to investigate microstructures of heat affected zones for a low alloy carbon steel pipe under a multipass weld. The commercial finite element code SYSWELD is used to compute thermal cycles during multipass weld. The numerical results such as thermal cycles and size of heat affected zone are compared with those of the experiment and the two results show a good agreement. In addition, the microstructure and hardness and investigated from the weldment in detail. The weakest location is founded at intercritical region near the base metal.

  11. Marginal adaptation of class V composite restorations submitted to thermal and mechanical cycling

    Directory of Open Access Journals (Sweden)

    Denise Sa Maia CASSELLI

    2013-01-01

    Full Text Available Objective This study evaluated the effect of the margin location and an adhesive system on the marginal adaptation of composite restorations. Material and Methods Class V cavities were prepared in bovine teeth with the gingival margin on the dentin and the incisal margin on the enamel. The cavities were restored with a micro-hybrid composite resin using an etch-and-rinse [Single Bond 2 (SB] or a self-etching adhesive [Clearfil SE Bond (CL]. After finishing and polishing the restorations, epoxy replicas were prepared. The marginal adaptation was analyzed using scanning electronic microscopy (SEM, 500 x magnification. The higher gap width in each margin was recorded (T0. After the first evaluation, the samples were submitted to thermal cycling (2,000 cycles of 5°C±2°C followed by 55°C±2°C – T1 and mechanical cycling (100,000 cycles of 50 kN and 2 Hz – T2. Replicas of samples were rebuilt after each cycling and analyzed under SEM. The data were submitted to Mann-Whitney, Wilcoxon and Friedman testing (α=0.05. Results The SB presented higher gaps in the dentin than the enamel, while there was no difference between the substrate for the CL. In the dentin, the CL showed better marginal sealing than the SB. The opposite occurred in the enamel. There were no significant differences between the baseline, thermal and mechanical cycling for any experimental condition. Conclusions The outcomes of the present study showed that the adhesive system and margin location have an important effect on the marginal adaptation of composite restorations.

  12. Menstrual cycle characteristics in fertile women from Greenland, Poland and Ukraine exposed to perfluorinated chemicals

    DEFF Research Database (Denmark)

    Lyngsø, J; Ramlau-Hansen, C H; Høyer, Birgit Bjerre

    2013-01-01

    group overrepresenting the most fertile part of the population; retrospective information on menstrual cycle characteristics; the determination of cut-points for all three outcome variables; and lacking information on some determinants of menstrual cycle characteristics, such as stress, physical......STUDY QUESTION: Does perfluorooctane sulfonate (PFOS) and perfluorooctanate (PFOA) exposure disrupt the menstrual cyclicity? SUMMARY ANSWER: The female reproductive system may be sensitive to PFOA exposure, with longer menstrual cycle length at higher exposure. WHAT IS KNOWN ALREADY: PFOS and PFOA...... and May 2004 in Greenland, Poland and Ukraine. PARTICIPANTS/MATERIALS, SETTING, METHODS: Information on menstrual cycle characteristics was obtained by questionnaires together with a blood sample from each pregnant woman. Serum concentrations of PFOS and PFOA were measured by liquid chromatography tandem...

  13. Physicochemical Characteristics and Lipid Oxidation of Chicken Inner Fillets Subjected to Different Thermal Processing Types

    Directory of Open Access Journals (Sweden)

    NN Arguelo

    Full Text Available ABSTRACT The objective of this study was to evaluate the effects of different types of thermal processing on the physiochemical characteristics and lipid oxidation of chicken inner fillets. The study was divided into three assays. In the first assay, 50 chicken inner fillets were divided into five treatments, totaling 10 samples per treatment. Treatments consisted in cooking in water bath, electric oven, microwave oven, deep frying, or grilling. The analyzed variables were: cooking weight loss (CWL and lipid oxidation determined by thiobarbituric acid reactive substances (TBARS. In the second assay, 50 chicken inner fillets were divided into five treatments, totaling 10 samples per treatment. Each treatment consisted of the same cooking methods applied in the first assay, and storage for 48 hours under refrigeration and reheating in a microwave oven. The variable analyzed in the second assay was lipid oxidation (TBARS. In the third assay, 30 samples of chicken inner fillets were subjected to one, four and eight freeze-thaw cycles, after which meat pH, myofibrillar fragmentation index (MFI, water retention capacity (WRC, and lipid oxidation (TBARS were determined. Chicken inner fillets submitted to deep frying and cooked in a microwave oven presented greater lipid oxidation than the other cooking methods, and deep frying resulted in the highest cooking weight loss. Reheating chicken inner fillets in a microwave oven caused the highest meat lipid oxidation. Increasing the number of freeze-thaw cycles increases the pH, MFI, WRC and TBARS values of chicken inner fillets.

  14. Analyzing Thermal Characteristics of Urban Streets Using a Thermal Imaging Camera: A Case Study on Commercial Streets in Seoul, Korea

    Directory of Open Access Journals (Sweden)

    Sugie Lee

    2018-02-01

    Full Text Available Due to continuing city growth and global warming over the past decades, urban heat island (UHI effects, referring to the phenomena wherein the ambient air temperatures in cities are higher than those in rural areas, have become a serious threat to urban populations. Impervious surfaces, buildings with low-albedo materials, and a lack of vegetated areas are the major causes of poor urban thermal environments, particularly during the summer. Previous research has focused primarily on the thermal characteristics of individual building units. Few studies consider the impact of the street-scale thermal environments on the surface temperature, which affects pedestrian thermal comfort. The purpose of this study is to analyze the thermal characteristics of various physical elements on urban streets using thermal imaging cameras, and present policy implications for improving pedestrian thermal comfort. This study examines street-scale thermal environments of three major commercial streets: Garosu road, Serosu road, and Narosu road, in Seoul, Korea. This study conducted field measurements both during the day and the night in June 2017 in order to investigate changes in the urban surface temperatures across time. The results show that street trees are the most effective mitigation element for reducing surface temperatures. With regard to building use types, the highest surface temperatures are typically measured near restaurant buildings. Building façades that are dark-colored or partially covered with a metal contribute to high surface temperatures. Similarly, the temperatures of artificial turf or wooden decks on urban streets are also significantly high during the daytime. The thermal characteristics of various urban street elements should be considered to reduce the surface temperature and mitigate the urban heat island effect.

  15. Theoretical and experimental analysis of the vacuum pressure in a vacuum glazing after extreme thermal cycling

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Yueping; Hyde, Trevor J.; Hewitt, Neil [Ulster Univ., Newtownabbey, Northern Ireland (United Kingdom). Centre for Sustainable Technologies; Eames, Philip C. [Warwick Univ., Coventry (United Kingdom). Warwick Inst. for Sustainable Energy and Resources

    2008-07-01

    Details of theoretical and experimental studies of the change in vacuum pressure within a vacuum glazing after extreme thermal cycling are presented. The vacuum glazing was fabricated at low temperature using an indium edge seal. It comprised two 4 mm thick 0.4 m by 0.4 m low-emittance glass panes separated by an array of stainless steel pillars with a diameter of 0.32 mm and a height of 0.2 mm. After thermal cycling in the temperature range -30 C to +50 C on one side of the sample, while maintaining 22 C on the other side, it was found that the glass to glass heat conductance of the sample had increased by 8.2%. The vacuum pressure within the evacuated gap was determined to have increased from 0.01 Pa to 0.15 Pa using the model of Corrucini. This is at the upper limit of the range where the effect of gas pressure on the thermal performance of vacuum glazing can be ignored. The degradation of vacuum level determined was corroborated by the change in glass surface temperatures. (orig.)

  16. Simulated Solar Flare X-Ray and Thermal Cycling Durability Evaluation of Hubble Space Telescope Thermal Control Candidate Replacement Materials

    Science.gov (United States)

    deGroh, Kim K.; Banks, Bruce A.; Sechkar, Edward A.; Scheiman, David A.

    1998-01-01

    During the Hubble Space Telescope (HST) second servicing mission (SM2), astronauts noticed that the multilayer insulation (MLI) covering the telescope was damaged. Large pieces of the outer layer of MLI (aluminized Teflon fluorinated ethylene propylene (Al-FEP)) were torn in several locations around the telescope. A piece of curled up Al-FEP was retrieved by the astronauts and was found to be severely embrittled, as witnessed by ground testing. Goddard Space Flight Center (GSFC) organized a HST MLI Failure Review Board (FRB) to determine the damage mechanism of FEP in the HST environment, and to recommend replacement insulation material to be installed on HST during the third servicing mission (SM3) in 1999. Candidate thermal control replacement materials were chosen by the FRB and tested for environmental durability under various exposures and durations. This paper describes durability testing of candidate materials which were exposed to charged particle radiation, simulated solar flare x-ray radiation and thermal cycling under load. Samples were evaluated for changes in solar absorptance and tear resistance. Descriptions of environmental exposures and durability evaluations of these materials are presented.

  17. Research on transient thermal process of a friction brake during repetitive cycles of operation

    Science.gov (United States)

    Slavchev, Yanko; Dimitrov, Lubomir; Dimitrov, Yavor

    2017-12-01

    Simplified models are used in the classical engineering analyses of the friction brake heating temperature during repetitive cycles of operation to determine basically the maximum and minimum brake temperatures. The objective of the present work is to broaden and complement the possibilities for research through a model that is based on the classical scheme of the Newton's law of cooling and improves the studies by adding a disturbance function for a corresponding braking process. A general case of braking in non-periodic repetitive mode is considered, for which a piecewise function is defined to apply pulse thermal loads to the system. Cases with rectangular and triangular waveforms are presented. Periodic repetitive braking process is also studied using a periodic rectangular waveform until a steady thermal state is achieved. Different numerical methods such as the Euler's method, the classical fourth order Runge-Kutta (RK4) and the Runge-Kutta-Fehlberg 4-5 (RKF45) are used to solve the non-linear differential equation of the model. The constructed model allows during pre-engineering calculations to be determined effectively the time for reaching the steady thermal state of the brake, to be simulated actual braking modes in vehicles and material handling machines, and to be accounted for the thermal impact when performing fatigue calculations.

  18. Thermal and Mechanical Characteristics of Polymer Composites Based on Epoxy Resin, Aluminium Nanopowders and Boric Acid

    Science.gov (United States)

    Nazarenko, O. B.; Melnikova, T. V.; Visakh, P. M.

    2016-01-01

    The epoxy polymers are characterized by low thermal stability and high flammability. Nanoparticles are considered to be effective fillers of polymer composites for improving their thermal and functional properties. In this work, the epoxy composites were prepared using epoxy resin ED-20, polyethylene polyamine as a hardener, aluminum nanopowder and boric acid fine powder as flame-retardant filler. The thermal characteristics of the obtained samples were studied using thermogravimetric analysis and differential scanning calorimetry. The mechanical characteristics of epoxy composites were also studied. It was found that an addition of all fillers enhances the thermal stability and mechanical characteristics of the epoxy composites. The best thermal stability showed the epoxy composite filled with boric acid. The highest flexural properties showed the epoxy composite based on the combination of boric acid and aluminum nanopowder.

  19. Thermal and chemical characteristics of hot water springs in the ...

    African Journals Online (AJOL)

    2011-02-15

    Feb 15, 2011 ... Keywords: thermal springs, South Africa, macro and micro-elements, geological controls. Introduction. A spring is .... features of the study areas in view of their impact on the physi- cal location of the springs and on .... rating the resultant solutions over open fires in clay pots' (Kent,. 1942: 35). According to ...

  20. Thermal Internal Boundary Layer characteristics at a tropical coastal ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    examined with the help of measurements carried out with a mini-SODAR (SOund Detection And ..... moisture upwards and periodic intrusion of mar- ..... Ocean System 2. 351–362. Kunhikrishnan P K, Gupta K S, Ramachandran R, Prakash. J W, Nair K N 1993 Study on thermal internal boundary layer structure over Thumba, ...

  1. A Literature Review of Shock Sensitivity Changes of TATB Due to Thermal Cycling

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, Boyd [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); New Mexico Inst. of Mining and Technology, Socorro, NM (United States). Dept. of Mechanical Engineering

    2016-07-15

    Insensitive high explosives (IHEs) based on 1,3,5-triamino 2,4,6-trinitro-benzene (TATB) are the IHEs of choice for use in nuclear warheads over conventional high explosives when safety is the only consideration, because they are very insensitive to thermal or mechanical initiation stimuli. It is this inherent insensitivity to high temperatures, shock, and impact, which provides detonation design challenges when designing TATB explosive systems while at the same time providing a significant level of protection against accidental initiation. Although classified as IHE, over the past few years the focus on explosive safety has demonstrated that the shock sensitivity of TATB is influenced with respect to temperature. A number of studies have been performed on TATB and TATB formulations, plastic bonded explosives (PBX) 9502, and LX-17-01 (LX-17), which demonstrates the increase in shock sensitivity of the explosive after it has been preheated or thermally cycled over various temperature ranges. Many studies suggest the change in sensitivity is partly due to the decomposition rates of the temperature elevated TATB. Others point to the coefficient of thermal expansion, the crystalline structures of TATB and/or the combination of all factors, which create voids which can become active hot spots. During thermal cycling, TATB is known to undergo an irreversible increase in specific volume called ratchet growth. This increase in specific volume correlates to a decrease in density. This decrease in density and increase in volume, demonstrate the creations of additional void spaces which could serve as potential new initiation hot spots thus, increasing the overall sensitivity of the HE. This literature review evaluates the published works to understand why the shock sensitivity of TATB-based plastic bonded explosives (PBXs) changes with temperature.

  2. Environmental cycling of cellulosic thermal insulation and its influence on fire performance

    Science.gov (United States)

    Lawson, J. R.

    1984-08-01

    A study was conducted on climatological data for eleven cities located throughout the United States. Findings from this environmental study were used to develop conditioning cycles for a research project on the influence of environments on the fire performance of loose-fill cellulosic thermal insulation. Six cellulosic insulation materials with different compositions of fire retardant chemicals at an add-on level of 25% by weight were specially manufactured for this study. These materials were tested for fire performance using the smoldering combustion test and the attic flooring radiant panel test to establish a baseline. After the materials were exposed to the various environmental cycles, they were tested for fire performance. Results from these tests show that environmental exposure can have a significant effect on the fire performance of cellulosic insulation materials and indicates that long term fire protection provided by fire retardant compounds may be limited.

  3. Static behavior and the effects of thermal cycling in hybrid laminates

    Science.gov (United States)

    Liber, T. M.; Daniel, I. M.; Chamis, C. C.

    1977-01-01

    Static stiffness, strength and ultimate strain after thermal cycling were investigated for graphite/Kevlar 49/epoxy and graphite/S-glass/epoxy angle-ply laminates. Tensile stress-strain curves to failure and uniaxial tensile properties were determined, and theoretical predictions of modulus, Poisson's ratio and ultimate strain, based on linear lamination theory, constituent ply properties and measured strength, were made. No significant influence on tensile stress properties due to stacking sequence variations was observed. In general, specimens containing two 0-degree Kevlar or S-glass plies were found to behave linearly to failure, while specimens containing 4 0-degree Kevlar or S-glass plies showed some nonlinear behavior.

  4. Ex Situ Thermal Cycle Annealing of Molecular Beam Epitaxy Grown HgCdTe/Si Layers

    Science.gov (United States)

    2010-01-01

    matched bulk CdZnTe substrates. Recent work6 on CdTe/Si has shown that in situ thermal cycle annealing (TCA), where annealing is performed intermittently...was grown on a bulk CdZnTe substrate for comparison. The HgCdTe was grown at 185C, with a growth rate of 2 lm/h. The typical HgCdTe layer...Cd composition. The HgCdTe layers grown on bulk CdZnTe samples, which were subjected to annealing condi- tions similar to those for the HgCdTe layers

  5. Effect of Thermal Cycling on the Strength and Texture of Concrete for Nuclear Safety Structures

    Directory of Open Access Journals (Sweden)

    Š. Hošková

    2001-01-01

    Full Text Available The effect of thermal cycling (freezing and thawing on the texture and strength of two types of concrete is studied: 1. Concrete used for a containment structure at NPP Temelín (Czech Republic - so-called TEMELÍN concrete.2. Highly resistant PENLY concrete, which was used as a standard because of its high quality, proved by the research carried out in a European Commission project. The results for the two samples of concrete are compared.

  6. Effects of thermal and moisture cycling on the internal structure of stitched RTM laminates

    Science.gov (United States)

    Walker, Jeff; Roundy, Lance; Goering, Jon

    1993-01-01

    Conventional aerospace composites are strong and stiff in the directions parallel to the carbon fibers, but they are prone to delaminations and damage in the through-the-thickness directions. Recent research has shown that substantial improvements in damage tolerance are obtained from textile composites with Z-direction reinforcement provided by stitching, weaving, or braiding. Because of the mismatch in thermal and moisture expansion properties of the various material components, there is a potential for microcracks to develop in the resin matrix. These cracks can form to relieve the mechanical stresses that are generated during curing or in-service temperature cycles.

  7. Interim assessment of the denatured /sup 233/U fuel cycle: feasibility and nonproliferation characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Abbott, L.S.; Bartine, D.E.; Burns, T.J. (eds.)

    1979-12-01

    A fuel cycle that employs /sup 233/U denatured with /sup 238/U and mixed with thorium fertile material is examined with respect to its proliferation-resistance characteristics and its technical and economic feasibility. The rationale for considering the denatured /sup 233/U fuel cycle is presented, and the impact of the denatured fuel on the performance of Light-Water Reactors, Spectral-Shift-Controlled Reactors, Gas-Cooled Reactors, Heavy-Water Reactors, and Fast Breeder Reactors is discussed. The scope of the R, D and D programs to commercialize these reactors and their associated fuel cycles is also summarized and the resource requirements and economics of denatured /sup 233/U cycles are compared to those of the conventional Pu/U cycle. In addition, several nuclear power systems that employ denatured /sup 233/U fuel and are based on the energy center concept are evaluated.

  8. Examining Associations of Environmental Characteristics with Recreational Cycling Behaviour by Street-Level Strava Data.

    Science.gov (United States)

    Sun, Yeran; Du, Yunyan; Wang, Yu; Zhuang, Liyuan

    2017-06-15

    Policymakers pay much attention to effectively increasing frequency of people's cycling in the context of developing sustainable and green cities. Investigating associations of environmental characteristics and cycling behaviour could offer implications for changing urban infrastructure aiming at encouraging active travel. However, earlier examinations of associations between environmental characteristics and active travel behaviour are limited by low spatial granularity and coverage of traditional data. Crowdsourced geographic information offers an opportunity to determine the fine-grained travel patterns of people. Particularly, Strava Metro data offer a good opportunity for studies of recreational cycling behaviour as they can offer hourly, daily or annual cycling volumes with different purposes (commuting or recreational) in each street across a city. Therefore, in this study, we utilised Strava Metro data for investigating associations between environmental characteristics and recreational cycling behaviour at a large spatial scale (street level). In this study, we took account of population density, employment density, road length, road connectivity, proximity to public transit services, land use mix, proximity to green space, volume of motor vehicles and traffic accidents in an empirical investigation over Glasgow. Empirical results reveal that Strava cyclists are more likely to cycle for recreation on streets with short length, large connectivity or low volume of motor vehicles or on streets surrounded by residential land.

  9. Examining Associations of Environmental Characteristics with Recreational Cycling Behaviour by Street-Level Strava Data

    Directory of Open Access Journals (Sweden)

    Yeran Sun

    2017-06-01

    Full Text Available Policymakers pay much attention to effectively increasing frequency of people’s cycling in the context of developing sustainable and green cities. Investigating associations of environmental characteristics and cycling behaviour could offer implications for changing urban infrastructure aiming at encouraging active travel. However, earlier examinations of associations between environmental characteristics and active travel behaviour are limited by low spatial granularity and coverage of traditional data. Crowdsourced geographic information offers an opportunity to determine the fine-grained travel patterns of people. Particularly, Strava Metro data offer a good opportunity for studies of recreational cycling behaviour as they can offer hourly, daily or annual cycling volumes with different purposes (commuting or recreational in each street across a city. Therefore, in this study, we utilised Strava Metro data for investigating associations between environmental characteristics and recreational cycling behaviour at a large spatial scale (street level. In this study, we took account of population density, employment density, road length, road connectivity, proximity to public transit services, land use mix, proximity to green space, volume of motor vehicles and traffic accidents in an empirical investigation over Glasgow. Empirical results reveal that Strava cyclists are more likely to cycle for recreation on streets with short length, large connectivity or low volume of motor vehicles or on streets surrounded by residential land.

  10. Technical Feasibility Study of Thermal Energy Storage Integration into the Conventional Power Plant Cycle

    Directory of Open Access Journals (Sweden)

    Jacek D. Wojcik

    2017-02-01

    Full Text Available The current load balance in the grid is managed mainly through peaking fossil-fuelled power plants that respond passively to the load changes. Intermittency, which comes from renewable energy sources, imposes additional requirements for even more flexible and faster responses from conventional power plants. A major challenge is to keep conventional generation running closest to the design condition with higher load factors and to avoid switching off periods if possible. Thermal energy storage (TES integration into the power plant process cycle is considered as a possible solution for this issue. In this article, a technical feasibility study of TES integration into a 375-MW subcritical oil-fired conventional power plant is presented. Retrofitting is considered in order to avoid major changes in the power plant process cycle. The concept is tested based on the complete power plant model implemented in the ProTRAX software environment. Steam and water parameters are assessed for different TES integration scenarios as a function of the plant load level. The best candidate points for heat extraction in the TES charging and discharging processes are evaluated. The results demonstrate that the integration of TES with power plant cycle is feasible and provide a provisional guidance for the design of the TES system that will result in the minimal influence on the power plant cycle.

  11. Optimisation of a Kalina cycle for a central receiver solar thermal power plant with direct steam generation

    DEFF Research Database (Denmark)

    Modi, Anish; Haglind, Fredrik

    2014-01-01

    Central receiver solar thermal power plants are regarded as one of the promising ways to generate electricity in near future. They offer the possibility of using high temperatures and pressures to achieve high efficiencies with standard power cycles. A direct steam generation approach can be used...... for a central receiver solar thermal power plant with direct steam generation. The variation in the cycle performance with respect to the turbine inlet ammonia mass fraction and pressure and a comparison of the initial investment with that of the basic Rankine cycle are also presented. Only high live steam...... for such plants for improved performance. This approach can also be combined with using advanced power cycles like the Kalina cycle, which uses a zeotropic mixture of ammonia and water instead of pure water as the working fluid. This paper presents the optimisation of a particular Kalina cycle layout...

  12. Evaluation of Thermal Endurance Characteristics of Hard Polyurethane Foams by Dynamic Compression Modulus

    National Research Council Canada - National Science Library

    Adachi, Hiromasa; Hasegawa, Teruo

    2004-01-01

      For evaluation of thermal endurance in foamed plastics, temperature and time characteristics of compression dynamic modulus of four hard polyurethane foams were investigated by the dynamic viscoelastic measurements...

  13. Radiators in hydronic heating installations structure, selection and thermal characteristics

    CERN Document Server

    Muniak, Damian Piotr

    2017-01-01

    This book addresses key design and computational issues related to radiators in hydronic heating installations. A historical outline is included to highlight the evolution of radiators and heating technologies. Further, the book includes a chapter on thermal comfort, which is the decisive factor in selecting the ideal heating system and radiator type. The majority of the book is devoted to an extensive discussion of the types and kinds of radiators currently in use, and to identifying the reasons for the remarkable diversity of design solutions. The differences between the solutions are also addressed, both in terms of the effects of operation and of the thermal comfort that needs to be ensured. The book then compares the advantages and disadvantages of each solution, as well as its potential applications. A detailed discussion, supported by an extensive theoretical and mathematical analysis, is presented of the computational relations that are used in selecting the radiator type. The dynamics of radiator hea...

  14. Thermal Characteristics of Grooved Heat pipe with Hybrid Nanofluids

    Directory of Open Access Journals (Sweden)

    W S Han

    2011-01-01

    Full Text Available In the present study, the specially designed grooved heat pipe charged with nanofluids was investigated in terms of various parameters such as heat transfer rate(50∼300W with 50 W interval, volume concentration(0.005%, 0.05%, 0.1%, and hybrid combinations, inclination(5°, 45°, 90°, cooling water temperature (1℃, 10℃, and 20℃, surface state, transient state and so on. Hybrid nanofluids with different volume concentration ratios with Ag-H2O and Al2O3-H2O were used as working fluids on a grooved heat pipe(GHP. Comparing with the pure water system, nanofluidic and hybrid nanofluidic system shows greater overall thermal resistance with increasing nano-particle concentration. Also hybrid nanofluids make the system deteriorate in terms of thermal resistance. The post nanofluid experimental data regarding GHP show that the heat transfer performance is similar to the results of nanofluid system. The thermal performance of a grooved heat pipe with nanofluids and hybrid nanofluids were varied with driving parameters but they led to worse system performance.

  15. The effect of thermal cycling on the shear bond strength of porcelain/Ti-6Al-4V interfaces.

    Science.gov (United States)

    Sendão, Isabel A; Alves, Alexandra C; Galo, Rodrigo; Toptan, Fatih; Silva, Filipe S; Ariza, Edith

    2015-04-01

    The aim of the study was to evaluate the effect of thermal cycling on the shear bond strength of the porcelain/Ti-6Al-4V interfaces prepared by two different processing routes and metallic surface conditions. Polished and SiO2 particle abraded Ti-6Al-4V alloy and Triceram bonder porcelain were used to produce the interfaces. Porcelain-to-metal specimens were processed by conventional furnace firing and hot pressing. Thermal cycling was performed in Fusayama's artificial saliva for 5000 cycles between 5 ± 1 and 60 ± 2°C. After thermal cycling, shear bond tests were carried out by using a custom-made stainless steel apparatus. The results were analyzed using t-Student test and non-parametric Kruskal-Wallis test (p<0.01). Most of the polished-fired specimens were fractured during thermal cycling; thus, it was not possible to obtain the shear bond strength results for this group. Sandblasted-fired, polished-hot pressed, and sandblasted-hot pressed specimens presented the shear bond strength values of 76.2 ± 15.9, 52.2 ± 23.6, and 59.9 ± 22.0 MPa, respectively. Statistical analysis indicated that thermal cycling affected the polished specimens processed by firing, whereas a significant difference was not observed on the other groups. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Effect of Thermal Cycle on the Formation of Intermetallic Compounds in Laser Welding of Aluminum-Steel Overlap Joints

    Science.gov (United States)

    Fan, J.; Thomy, C.; Vollertsen, F.

    The intermetallic compound (IMC) (or intermetallic phase layer) has a significant influence on the mechanical properties ofjoints between dissimilar metals obtained by thermal processes such as laser welding. Its formation is basically affected by thermal cycles in the joining or contact zone, where the IMC is formed. Within this study, the influence of the thermal cycle on the formation of the IMC during laser welding of an aluminum-steel (Al99.5-DC01) overlap joint was investigated. The temperature was measured directly by a thermocouple, and the weld seam was analyzed by scanning electron microscope (SEM). The influence of peak temperature, cooling time and the integral of the thermal cycle on the thickness of the IMC was identified and discussed. It was identified that cooling time has the biggest influence on the thickness of the IMC.

  17. Thermal Impact of Operating Conditions on the Performance of a Combined Cycle Gas Turbine

    Directory of Open Access Journals (Sweden)

    Thamir K. Ibrahim

    2012-08-01

    Full Text Available The combined cycle gas-turbine (CCGT power plant is a highly developed technology which generates electricalpower at high efficiencies. The first law of thermodynamics is used for energy analysis of the performance of theCCGT plant. The effects of varying the operating conditions (ambient temperature, compression ratio, turbine inlettemperature, isentropic compressor and turbine efficiencies, and mass flow rate of steam on the performance of theCCGT (overall efficiency and total output power were investigated. The programming of the performance model forCCGT was developed utilizing MATLAB software. The simulation results for CCGT show that the overall efficiencyincreases with increases in the compression ratio and turbine inlet temperature and with decreases in ambienttemperature. The total power output increases with increases in the compression ratio, ambient temperature, andturbine inlet temperature. The peak overall efficiency was reached with a higher compression ratio and low ambienttemperature. The overall efficiencies for CCGT were very high compared to the thermal efficiency of GT plants. Theoverall thermal efficiency of the CCGT quoted was around 57%; hence, the compression ratios, ambient temperature,turbine inlet temperature, isentropic compressor and turbine efficiencies, and mass flow rate of steam have a stronginfluence on the overall performance of the CCGT cycle.

  18. Theoretical and experimental analysis of the vacuum pressure in a vacuum glazing after extreme thermal cycling

    Energy Technology Data Exchange (ETDEWEB)

    Fang, Yueping; Hyde, Trevor; Hewitt, Neil [Centre for Sustainable Technologies, School of the Built Environment, University of Ulster, Newtownabbey, BT37 0QB N. Ireland (United Kingdom); Eames, Philip C. [Centre for Renewable Energy Research, University of Loughborough (United Kingdom)

    2009-09-15

    Details of theoretical and experimental studies of the change in vacuum pressure within a vacuum glazing after extreme thermal cycling are presented. The vacuum glazing was fabricated at low temperature using an indium-copper-indium edge seal. It comprised two 4 mm thick 0.4 m by 0.4 m glass panes with low-emittance coatings separated by an array of stainless steel support pillars spaced at 25 mm with a diameter of 0.4 mm and a height of 0.15 mm. Thermal cycling tests were undertaken in which the air temperature on one side of the sample was taken from -30 C to +50 C and back to -30 C 15 times while maintaining an air temperature of 22 C on the other side. After this test procedure, it was found that the glass to glass heat conductance at the centre glazing area had increased by 10.1% from which the vacuum pressure within the evacuated space was determined to have increased from the negligible level of less than 0.1 Pa to 0.16 Pa using the model of Corrucini. Previous research has shown that if the vacuum pressure is less than 0.1 Pa, the effect of conduction through the residual gas on the total glazing heat transfer is negligible. The degradation of vacuum level determined was corroborated by the change in glass surface temperatures. (author)

  19. Procedure to Determine Thermal Characteristics and Groundwater Influence in Heterogeneous Subsoil by an Enhanced Thermal Response Test and Numerical Modeling

    Science.gov (United States)

    Aranzabal, Nordin; Martos, Julio; Montero, Álvaro; Monreal, Llúcia; Soret, Jesús; Torres, José; García-Olcina, Raimundo

    2016-04-01

    Ground thermal conductivity and borehole thermal resistance are indispensable parameters for the optimal design of subsoil thermal processes and energy storage characterization. The standard method to determine these parameters is the Thermal Response Test (TRT) which results are evaluated by models considering the ground being homogeneous and isotropic. This method obtains an effective ground thermal conductivity which represents an average of the thermal conductivity along the different layers crossed by perforation. In order to obtain a ground thermal conductivity profile as a function of depth two additional key factors are required, first, a new significant data set: a temperature profile along the borehole; and second, a new analysis procedure to extract ground heterogeneity from the recorded data. This research work presents the results of an analysis procedure, complementing the standard TRT analysis, which allows to estimate the thermal conductivity profile from a temperature profile measured along the borehole during a TRT. In the analysis procedure, a 3D Finite Element Model (FEM) is used to fit simulation results with experimental data, by a set of iterative simulations. This methodology is applied to a data set obtained throughout a TRT of 1kW heat power injection in a 30m depth Borehole Heat Exchange (BHE) facility. A highly conductive layer have been detected and located at 25 m depth. In addition, a novel automated device to obtain temperature profiles along geothermal pipes with or without fluid flow is presented. This sensor system is intended to improve the standard TRT and it allows the collection of depth depending thermal characteristics of the subsoil geological structure. Currently, some studies are being conducted in double U-pipe borehole installations in order to improve previously introduced analysis procedure. From a numerical model simulation that takes into account advective effects is pretended to estimate underground water velocity

  20. Effect of Autoclave Cycles on Surface Characteristics of S-File Evaluated by Scanning Electron Microscopy

    OpenAIRE

    Razavian, Hamid; Iranmanesh, Pedram; Mojtahedi, Hamid; Nazeri, Rahman

    2015-01-01

    Introduction: Presence of surface defects in endodontic instruments can lead to unwanted complications such as instrument fracture and incomplete preparation of the canal. The current study was conducted to evaluate the effect of autoclave cycles on surface characteristics of S-File by scanning electron microscopy (SEM). Methods and Materials: In this experimental study, 17 brand new S-Files (#30) were used. The surface characteristics of the files were examined in four steps (without autocla...

  1. Laser High-Cycle Thermal Fatigue of Pulse Detonation Engine Combustor Materials Tested

    Science.gov (United States)

    Zhu, Dong-Ming; Fox, Dennis S.; Miller, Robert A.

    2001-01-01

    Pulse detonation engines (PDE's) have received increasing attention for future aerospace propulsion applications. Because the PDE is designed for a high-frequency, intermittent detonation combustion process, extremely high gas temperatures and pressures can be realized under the nearly constant-volume combustion environment. The PDE's can potentially achieve higher thermodynamic cycle efficiency and thrust density in comparison to traditional constant-pressure combustion gas turbine engines (ref. 1). However, the development of these engines requires robust design of the engine components that must endure harsh detonation environments. In particular, the detonation combustor chamber, which is designed to sustain and confine the detonation combustion process, will experience high pressure and temperature pulses with very short durations (refs. 2 and 3). Therefore, it is of great importance to evaluate PDE combustor materials and components under simulated engine temperatures and stress conditions in the laboratory. In this study, a high-cycle thermal fatigue test rig was established at the NASA Glenn Research Center using a 1.5-kW CO2 laser. The high-power laser, operating in the pulsed mode, can be controlled at various pulse energy levels and waveform distributions. The enhanced laser pulses can be used to mimic the time-dependent temperature and pressure waves encountered in a pulsed detonation engine. Under the enhanced laser pulse condition, a maximum 7.5-kW peak power with a duration of approximately 0.1 to 0.2 msec (a spike) can be achieved, followed by a plateau region that has about one-fifth of the maximum power level with several milliseconds duration. The laser thermal fatigue rig has also been developed to adopt flat and rotating tubular specimen configurations for the simulated engine tests. More sophisticated laser optic systems can be used to simulate the spatial distributions of the temperature and shock waves in the engine. Pulse laser high-cycle

  2. Effect of Autoclave Cycles on Surface Characteristics of S-File Evaluated by Scanning Electron Microscopy.

    Science.gov (United States)

    Razavian, Hamid; Iranmanesh, Pedram; Mojtahedi, Hamid; Nazeri, Rahman

    2016-01-01

    Presence of surface defects in endodontic instruments can lead to unwanted complications such as instrument fracture and incomplete preparation of the canal. The current study was conducted to evaluate the effect of autoclave cycles on surface characteristics of S-File by scanning electron microscopy (SEM). In this experimental study, 17 brand new S-Files (#30) were used. The surface characteristics of the files were examined in four steps (without autoclave, 1 autoclave cycle, 5 autoclave cycles and 10 autoclave cycles) by SEM under 200× and 1000× magnifications. Data were analyzed using the SPSS software and the paired sample t-test, independent sample t-test and multifactorial repeated measures ANOVA. The level of significance was set at 0.05. New files had debris and pitting on their surfaces. When the autoclave cycles were increased, the mean of surface roughness also increased at both magnifications (Pautoclave increased the surface roughness of the files and this had was directly related to the number of autoclave cycles.

  3. Moisture sorption and thermal characteristics of polyaramide blend fabrics

    OpenAIRE

    GENÇ, Gözde; Alp, Burcu; Balköse, Devrim; Ülkü, Semra; CiRELi, Aysun

    2006-01-01

    Four types of fabrics woven from various polyaramid fibers of Nomex and Kevlar blends were characterized by morphology, XRD, elemental analysis, thermal analysis, and moisture adsorption isotherms. The blends consisted of Polybenzimidazole/ Kevlar blend (40% FBI and 60% Kevlar®), Nomex Delta A (blend of 60% Kevlar and 40% Nomex®), Nomex Delta T (blend of 75% Nomex, 23% Kevlar, and 2% P140 antistatic fiber), and Nomex III (fabric with a 95/5 blend of Nomex and Kevlar) containing 1% steel fiber...

  4. Thermal analysis of a Phase Change Material for a Solar Organic Rankine Cycle

    Science.gov (United States)

    Iasiello, M.; Braimakis, K.; Andreozzi, A.; Karellas, S.

    2017-11-01

    Organic Rankine Cycle (ORC) is a promising technology for low temperature power generation, for example for the utilization of medium temperature solar energy. Since heat generated from solar source is variable throughout the day, the implementation of Thermal Energy Storage (TES) systems to guarantee the continuous operation of solar ORCs is a critical task, and Phase Change Materials (PCM) rely on latent heat to store large amounts of energy. In the present study, a thermal analysis of a PCM for a solar ORC is carried out. Three different types of PCMs are analyzed. The energy equation for the PCM is modeled by using the heat capacity method, and it is solved by employing a 1Dexplicit finite difference scheme. The solar source is modeled with a time-variable temperature boundary condition, with experimental data taken from the literature for two different solar collectors. Results are presented in terms of temperature profiles and stored energy. It has been shown that the stored energy depends on the heat source temperature, on the employed PCM and on the boundary conditions. It has been demonstrated that the use of a metal foam can drastically enhance the stored energy due to the higher overall thermal conductivity.

  5. ANALYSIS OF THERMAL-CHEMICAL CHARACTERISTICS OF BIOMASS ENERGY PELLETS

    Directory of Open Access Journals (Sweden)

    Zorica Gluvakov

    2014-09-01

    Full Text Available In modern life conditions, when emphasis is on environmental protection and sustainable development, fuels produced from biomass are increasingly gaining in importance, and it is necessary to consider the quality of end products obtained from biomass. Based on the existing European standards, collected literature and existing laboratory methods, this paper presents results of testing individual thermal - chemical properties of biomass energy pellets after extrusion and cooling the compressed material. Analysing samples based on standard methods, data were obtained on the basis of which individual thermal-chemical properties of pellets were estimated. Comparing the obtained results with the standards and literature sources, it can be said that moisture content, ash content and calorific values are the most important parameters for quality analysis which decide on applicability and use-value of biomass energy pellets, as biofuel. This paper also shows the impact of biofuels on the quality of environmental protection. The conclusion provides a clear statement of quality of biomass energy pellets.

  6. Computational fluid dynamic (CFD) investigation of thermal uniformity in a thermal cycling based calibration chamber for MEMS

    Science.gov (United States)

    Gui, Xulong; Luo, Xiaobing; Wang, Xiaoping; Liu, Sheng

    2015-12-01

    Micro-electrical-mechanical system (MEMS) has become important for many industries such as automotive, home appliance, portable electronics, especially with the emergence of Internet of Things. Volume testing with temperature compensation has been essential in order to provide MEMS based sensors with repeatability, consistency, reliability, and durability, but low cost. Particularly, in the temperature calibration test, temperature uniformity of thermal cycling based calibration chamber becomes more important for obtaining precision sensors, as each sensor is different before the calibration. When sensor samples are loaded into the chamber, we usually open the door of the chamber, then place fixtures into chamber and mount the samples on the fixtures. These operations may affect temperature uniformity in the chamber. In order to study the influencing factors of sample-loading on the temperature uniformity in the chamber during calibration testing, numerical simulation work was conducted first. Temperature field and flow field were simulated in empty chamber, chamber with open door, chamber with samples, and chamber with fixtures, respectively. By simulation, it was found that opening chamber door, sample size and number of fixture layers all have effects on flow field and temperature field. By experimental validation, it was found that the measured temperature value was consistent with the simulated temperature value.

  7. Determination of Urban Thermal Characteristics on an Urban/Rural ...

    African Journals Online (AJOL)

    John Odindi

    a decline in vegetation density from the periphery led to an increase in LST. These results provide valuable insights into the value of remotely sensed datasets in understanding the implication of intra-urban LULC gradient on LST characteristics. Specifically, the study demonstrates the value of remotely sensed data as aids ...

  8. Exergy analysis of heat exchangers in the copper-chlorine thermochemical cycle to enhance thermal effectiveness and cycle efficiency

    National Research Council Canada - National Science Library

    Orhan, Mehmet F; Dincer, Ibrahim; Rosen, Marc A

    2011-01-01

    .... For this temperature level, the copper-chlorine (Cu-Cl) cycle is one of the most promising cycles that can be integrated with nuclear reactors for hydrogen production by decomposing water into its constituents...

  9. A Study of Thermal Analyses and Fundamental Combustion Characteristics for Thermal Utility with Biomass Volatile Matter

    Science.gov (United States)

    Ida, Tamio; Namba, Kunihiko; Sano, Hiroshi

    Based on un-use biomass utilities, Carbonized technology is noticed as material utilities and solid fuel. Therefore, this technology is tackling by national project as large-scale utilities. But, this technology is dehydrated volatiles matter during carbonized from biomass. Especially, Woody tar into one of volatile matter has vicious handling to get into trouble in carbonized equipment. In this study, we propose to get fundamental knowledge for effective thermal utility through thermal decompositions and fundamental combustion properties on experimental results. Woody tar has high caloric value (approximately 30MJ/kg) and high carbon ration. On the other hand, a woody vinegar liquid has thermal decomposition property close to water property with heat absorption as evaporation latent heat of water. In fundamental combustion experimental result, a woody tar has fl ammable combustion and surface combustion. Especially, a total combustion and ignition time properties has hyperbola relation to environment temperatures in furnace.

  10. Characterization of tin crystal orientation evolution during thermal cycling in lead-free solder joints

    Science.gov (United States)

    Zhou, Bite

    To address the long term reliability of lead-free solder joints in electronic devices during thermal cycling, the fundamental understanding of deformation mechanisms was studied using polarized light optical microscopy (PLM), electron backscatter diffraction (EBSD) in scanning electron microscopy (SEM), and synchrotron X-ray diffraction (XRD). Near-eutectic Sn-3.0(wt %) Ag-0.5(wt %) Cu (SAC305) lead-free solder joints were assessed in three different package designs: low-strain plastic ball grid array (PBGA), medium-strain fine-pitch ball grid array (BGA), and high-strain wafer-level-chip-scale package (WLCSP). The effect of microstructure evolution on solder failure is correlated with dislocation slip activities. The major failure mode in lead-free solder joints during thermal cycling that causes the electrical failure of the device is cracking in the bulk Sn near the Si chip/solder interface. Microstructure and Sn grain orientation evolution usually precedes crack development. A combined approach of both statistical analysis of a large number of solder joints, and detailed studies of individual solder balls was used to investigate the causes of fracture. Sn crystal orientation evolution and its effect on deformation was characterized in solder joints with different thermal histories, and compared with those from other package designs with different effective strain levels. The relationship between the initial dominant and localized recrystallized Sn grain orientations on crack development was investigated. It is found that in the low-strain package design, cracking is strongly correlated with Sn grain orientations with the [001] direction (c-axis) nearly aligned with the chip/solder interface. But no cracks were observed in solder balls with dominant orientations that have the c-axis normal to the interface plane. In higher-strain packages, however, cracking occurred in a variety of Sn grain orientations, and even solder balls with dominant orientations that are

  11. Influence of different treatments of the ceramic surface and thermal cycling on the bond strength of brackets to ceramic

    Directory of Open Access Journals (Sweden)

    Fernando Guerra SÁEZ

    Full Text Available Abstract Objective To evaluate in vitro the effect of different treatments of the ceramic surface and thermal cycling on the shear bond strength (SBS of metallic brackets bonded to feldspathic ceramic. Material and method Ceramic cylinders were divided into four groups (n=4 according to the treatment of ceramic surface: G1-Clearfil Ceramic Primer silane and Transbond XT (CCPT; G2-etched with 10% hydrofluoric acid (HFA for 60 s, CCP and Transbond XT (ACCPT; G3-etched with 10% HFA for 60 s, Ambar Adhesive and Transbond XT (AAAT; and, G4 - etched with 10% HFA for 60 s, RelyX Ceramic Primer silane -RCP, adhesive primer Transbond and Transbond XT (ACPPT. Brackets were bonded to the cylinders with Transbond XT and light-activated for 40 s with LED Radii Plus. All specimens were stored in deionized water at 37 °C for 24 h, and two cylinders from each group were subject to 7,000 thermal cycles in a thermal cycler (5 °C/55 °C. After storage and thermal cycling, the SBS test was performed at a crosshead speed of 1 mm/min. Data were subjected to two-way ANOVA and Tukey’s post hoc test (α=0.05. Result The SBS of ACCPT was significantly higher than the other groups (p<0.05. The specimens submitted to thermal cycling showed significantly lower SBS than those without thermal cycling (p<0.05, regardless the ceramic surface treatment. The ARI showed predominance of score 0 for all groups. Conclusion Acid etching, CCP silane and Transbond XT method obtained the best results for bracket bonding. Thermal cycling reduced SBS for all groups. Score 0 was predominant for ARI in all groups.

  12. Acoustic emission characteristics of copper alloys under low-cycle fatigue conditions

    Science.gov (United States)

    Krampfner, Y.; Kawamoto, A.; Ono, K.; Green, A.

    1975-01-01

    The acoustic emission (AE) characteristics of pure copper, zirconium-copper, and several copper alloys were determined to develop nondestructive evaluation schemes of thrust chambers through AE techniques. The AE counts rms voltages, frequency spectrum, and amplitude distribution analysis evaluated AE behavior under fatigue loading conditions. The results were interpreted with the evaluation of wave forms, crack propagation characteristics, as well as scanning electron fractographs of fatigue-tested samples. AE signals at the beginning of a fatigue test were produced by a sample of annealed alloys. A sample of zirconium-containing alloys annealed repeatedly after each fatigue loading cycle showed numerous surface cracks during the subsequent fatigue cycle, emitting strong-burst AE signals. Amplitude distribution analysis exhibits responses that are characteristic of certain types of AE signals.

  13. Fast thermal cycling of acetanilide and magnesium chloride hexahydrate for indoor solar cooking

    Energy Technology Data Exchange (ETDEWEB)

    El-Sebaii, A.A.; Al-Amir, S.; Al-Marzouki, F.M.; Faidah, Adel S.; Al-Ghamdi, A.A.; Al-Heniti, S. [Physics Dept., Faculty of Science, King Abdul Aziz Univ., P.O. Box 80203, Jeddah 21589 (Saudi Arabia)

    2009-12-15

    Solar cookers are broadly divided into a direct or focusing type, indirect or box-type and advanced solar cookers. The focusing and box-type solar cookers are for outdoor applications. The advanced solar cookers have the advantage of being usable indoors and thus solve one of the problems, which impede the social acceptance of solar cookers. The advanced type solar cookers are employing additional solar units that increase the cost. Therefore, the solar cooker must contain a heat storage medium to store thermal energy for use during off-sunshine hours. The main aim of this study is to investigate the influence of the melting/solidification fast cycling of the commercial grade acetanilide C{sub 8}H{sub 9}NO (T{sub m} = 116 C) and magnesium chloride hexahydrate MgCl{sub 2}.6H{sub 2}O (T{sub m} = 116.7 C) on their thermo-physical properties; such as melting point and latent heat of fusion, to be used as storage media inside solar cookers. Five hundred cycles have been performed. The thermo-physical properties are measured using the differential scanning calorimetric technique. The compatibility of the selected phase change materials (PCMs) with the containing material is also studied via the surface investigation, using the SIM technique, of aluminum and stainless steel samples embedded in the PCM during cycling. It is inferred that acetanilide is a promising PCM for cooking indoors and during low intensity solar radiation periods with good compatibility with aluminum as a containing material. However, MgCl{sub 2}.6H{sub 2}O is not stable during its thermal cycling (even with the extra water principle) due to the phase segregation problem; therefore, it is not recommended as a storage material inside solar cookers for cooking indoors. It is also indicated that MgCl{sub 2}.6H{sub 2}O is not compatible with either aluminum or stainless steel. (author)

  14. Isotopic Characteristics of Thermal Fluids from Mexican Subduction Zone

    Science.gov (United States)

    Taran, Y.; Inguaggiato, S.

    2007-05-01

    Chemical (major and trace elements) and isotopic (H,O,N,C,He) composition of waters and gases from thermal springs and geothermal wells of Mexican subduction zone have been measured. Three main geochemical profiles have been realized: (1) along the frontal Trans-Mexican Volcanic Belt (TMVB) zone through high- temperature Acoculco, Los Humeros, Los Azufres and La Primavera hydrothermal systems, Colima and Ceboruco volcanoes; (2) along the for-arc region of Pacific coast (12 groups of hot springs); (3) across the zone, from Pacific coast to TMVB, through the Jalisco Block. Fluids from El Chichon volcano in Chiapanecan arc system and Tacana volcano from the Central America Volcanic Arc have also been sampled. The frontal zone of TMVB is characterized by high 3He/4He ratios, from 7.2Ra in Ceboruco fumaroles to 7.6Ra in gases from Acoculco and Los Humeros calderas (Ra is atmospheric value of 1.4x10-6). These values are significantly higher than those published earlier in 80-s (up to 6.8Ra). Gases from coastal springs are low in 3He, usually < 1Ra with a minimum value of 0.2Ra in the northernmost submarine Punta Mita hot springs and a maximum value of 2.4Ra in La Tuna springs at the southern board of the Colima graben. An important feature of the TMVB thermal fluids is the absence of excess nitrogen in gases and, as a consequence, close to zero d15N values. In contrast, some coastal for-arc gases and gases from the Jalisco Block have high N2/Ar ratios and d15N up to +5 permil. Isotopic composition of carbon of CO2 along TMVB is close to typical "magmatic" values from -3 permil to -5 permil, but d13C of methane varies significantly indicating multiple sources of CH4 in geothermal fluids and a partial temperature control. High 3He/4He ratios and pure atmospheric nitrogen may indicate a low contribution of subducted sediments into the TMVB magmas and magmatic fluids. In contrast, El Chichon and Tacana fluids show some excess nitrogen (N2/Ar up to 500) and variable d15N, but

  15. Effects of thermal cycling on surface roughness, hardness and flexural strength of polymethylmethacrylate and polyamide denture base resins.

    Science.gov (United States)

    Ayaz, Elif Aydoğan; Bağış, Bora; Turgut, Sedanur

    2015-10-16

    The purpose of this study was to evaluate the effects of thermal cycling on the surface roughness, hardness and flexural strength of denture resins. Polyamide (PA; Deflex and Valplast) and polymethylmethacrylate (PMMA; QC-20 and Acron MC) denture materials were selected. A total of 180 specimens were fabricated and then divided into 3 groups. The first group (group 1) acted as a control and was not thermocycled. The second group (group 2) was subjected to thermocycling for 10,000 cycles in artificial saliva and 5,000 cycles in distilled water. The last group (group 3) was thermocycled for 20,000 cycles in artificial saliva and 10,000 cycles in distilled water. The surface roughness were measured with a profilometer. The hardness of the resins were measured with a Vickers Hardness Tester using a 100-gf load. The flexural strength test was performed using the universal test machine with a crosshead speed of 5 mm/min. Data were analyzed using statistical software. The results of the measurements in the 3 different tests were analyzed by Kruskal-Wallis test with Bonferroni correction. Multiple comparisons were made by Conover and Wilcoxon tests. There was a significant difference between the PMMA and PA groups in terms of surface roughness, hardness and transverse strength before and after thermal cycling (p<0.001). Thermal cycling did not change the surface roughness, hardness and flexural strength values of either the PMMA or PA group (p>0.001).

  16. Comparison Study of Thermal Insulation Characteristics from Oil Palm Fibre

    Directory of Open Access Journals (Sweden)

    Hassan S.

    2014-07-01

    Full Text Available In this study, investigation was conducted to study the use of solid biomass from palm oil mill as insulation material. The experimental study concentrates on using oil palm fiber to determine the unidirectional thermal conductivity, k. The experiment was conducted at different temperature ranges and packing density. The values of k obtained were found to be 0.2 W/m.K to 0.069 W/m.K for a packing density between 66 kg/m3 to 110 kg/m3, and at a temperature between 40ºC to 70ºC. Comparisons were made with others common insulating materials, and it was found that the experimental k values for oil palm waste insulation was lower by between 4 to 56 times for rockwool and between 7 to 57 times for glass fiber at low temperatures. The value k of oil palm fiber however showed an increase at higher temperatures and was lower at lower packing densities. Although not being able to match the k values of common insulators at higher temperatures, other factors such as cost and environmental benefits of using waste material should be taken into consideration and hence encouraging its use as at least a supplement to existing insulation materials

  17. Modelling occupants' personal characteristics for thermal comfort prediction.

    Science.gov (United States)

    Haldi, Frédéric; Robinson, Darren

    2011-09-01

    Based on results from a field survey campaign conducted in Switzerand, we show that occupants' variations in clothing choices, which are relatively unconstrained, are best described by the daily mean outdoor temperature and that major clothing adjustments occur rarely during the day. We then develop an ordinal logistic model of the probability distribution of discretised clothing levels, which results in a concise and informative expression of occupants' clothing choices. Results from both cross-validation and independent verification suggest that this model formulation may be used with confidence. Furthermore, the form of the model is readily generalisable, given the requisite calibration data, to environments where dress codes are more specific. We also observe that, for these building occupants, the prevailing metabolic activity levels are mostly constant for the whole range of surveyed environmental conditions, as their activities are relatively constrained by the tasks in hand. Occupants may compensate for this constraint, however, through the consumption of cold and hot drinks, with corresponding impacts on metabolic heat production. Indeed, cold drink consumption was found to be highly correlated with indoor thermal conditions, whilst hot drink consumption is best described by a seasonal variable. These variables can be used for predictive purposes using binary logistic models.

  18. Thermal transport characteristics of human skin measured in vivo using ultrathin conformal arrays of thermal sensors and actuators.

    Directory of Open Access Journals (Sweden)

    R Chad Webb

    Full Text Available Measurements of the thermal transport properties of the skin can reveal changes in physical and chemical states of relevance to dermatological health, skin structure and activity, thermoregulation and other aspects of human physiology. Existing methods for in vivo evaluations demand complex systems for laser heating and infrared thermography, or they require rigid, invasive probes; neither can apply to arbitrary regions of the body, offers modes for rapid spatial mapping, or enables continuous monitoring outside of laboratory settings. Here we describe human clinical studies using mechanically soft arrays of thermal actuators and sensors that laminate onto the skin to provide rapid, quantitative in vivo determination of both the thermal conductivity and thermal diffusivity, in a completely non-invasive manner. Comprehensive analysis of measurements on six different body locations of each of twenty-five human subjects reveal systematic variations and directional anisotropies in the characteristics, with correlations to the thicknesses of the epidermis (EP and stratum corneum (SC determined by optical coherence tomography, and to the water content assessed by electrical impedance based measurements. Multivariate statistical analysis establishes four distinct locations across the body that exhibit different physical properties: heel, cheek, palm, and wrist/volar forearm/dorsal forearm. The data also demonstrate that thermal transport correlates negatively with SC and EP thickness and positively with water content, with a strength of correlation that varies from region to region, e.g., stronger in the palmar than in the follicular regions.

  19. Thermal transport characteristics of human skin measured in vivo using ultrathin conformal arrays of thermal sensors and actuators.

    Science.gov (United States)

    Webb, R Chad; Pielak, Rafal M; Bastien, Philippe; Ayers, Joshua; Niittynen, Juha; Kurniawan, Jonas; Manco, Megan; Lin, Athena; Cho, Nam Heon; Malyrchuk, Viktor; Balooch, Guive; Rogers, John A

    2015-01-01

    Measurements of the thermal transport properties of the skin can reveal changes in physical and chemical states of relevance to dermatological health, skin structure and activity, thermoregulation and other aspects of human physiology. Existing methods for in vivo evaluations demand complex systems for laser heating and infrared thermography, or they require rigid, invasive probes; neither can apply to arbitrary regions of the body, offers modes for rapid spatial mapping, or enables continuous monitoring outside of laboratory settings. Here we describe human clinical studies using mechanically soft arrays of thermal actuators and sensors that laminate onto the skin to provide rapid, quantitative in vivo determination of both the thermal conductivity and thermal diffusivity, in a completely non-invasive manner. Comprehensive analysis of measurements on six different body locations of each of twenty-five human subjects reveal systematic variations and directional anisotropies in the characteristics, with correlations to the thicknesses of the epidermis (EP) and stratum corneum (SC) determined by optical coherence tomography, and to the water content assessed by electrical impedance based measurements. Multivariate statistical analysis establishes four distinct locations across the body that exhibit different physical properties: heel, cheek, palm, and wrist/volar forearm/dorsal forearm. The data also demonstrate that thermal transport correlates negatively with SC and EP thickness and positively with water content, with a strength of correlation that varies from region to region, e.g., stronger in the palmar than in the follicular regions.

  20. THERMAL CYCLING UNDER LOADING OF SINGLE CRYSTAL Cu-Al-Ni AFTER AGING

    Directory of Open Access Journals (Sweden)

    Ignacio Corro

    2016-06-01

    Full Text Available In this paper, a study of single crystal Cu-14.3Al-4.1Ni (%wt subjected to thermal cycling under loading is presented. Shape memory Cu-Al-Ni has low diffusion at temperatures above room temperature. Therefore, it is interesting to know your answer in working conditions and after being aged in this temperature range. Specimens were characterized before and after aging, using a device designed by the authors. Parameters such as critical temperatures and hysteresis width, the repeatability of the curves and the type of TM induced were analyzed. These parameters have changes then the aging or contribute to that may influence the design of applications.

  1. Numerical analysis of energy piles under different boundary conditions and thermal loading cycles

    Directory of Open Access Journals (Sweden)

    Khosravi Ali

    2016-01-01

    Full Text Available The thermo- mechanical behavior of energy piles has been studied extensively in recent years. In the present study, a numerical model was adapted to study the effect of various parameters (e.g. heating/cooling temperature, head loading condition and soil stiffness on the thermo-mechanical behavior of an energy pile installed in unsaturated sandstone. The results from the simulations were compared with measurements from a thermal response test on a prototype energy pile installed beneath a 1-story building at the US Air Force Academy (USAFA in Colorado Springs, CO. A good agreement was achieved between the results obtained from the prototype and the numerical models. A parametric evaluation were also carried out which indicated the significance of the stiffness of the unsaturated sandstone and pile’s head loading condition on stress-strain response of the energy pile during heating/cooling cycles.

  2. Modeling of Thermal Cycle CI Engine with Multi-Stage Fuel Injection

    Directory of Open Access Journals (Sweden)

    Arkadiusz Jamrozik

    2017-09-01

    Full Text Available This work presents a complete thermal cycle modeling of a four-stroke diesel engine with a three-dimensional simulation program CFD - AVL Fire. The object of the simulation was the S320 Andoria engine. The purpose of the study was to determine the effect of fuel dose distribution on selected parameters of the combustion process. As a result of the modeling, time spatial pressure distributions, rate of pressure increase, heat release rate and NO and soot emission were obtained for 3 injection strategies: no division, one pilot dose and one main dose and two pilot doses and one main dose. It has been found that the use of pilot doses on the one hand reduces engine hardness and lowers NO emissions and on the other hand, increases soot emissions.

  3. Personal, closed-cycle cooling and protective apparatus and thermal battery therefor

    Science.gov (United States)

    Klett, James W.; Klett, Lynn B.

    2004-07-20

    A closed-cycle apparatus for cooling a living body includes a heat pickup body or garment which permits evaporation of an evaporating fluid, transmission of the vapor to a condenser, and return of the condensate to the heat pickup body. A thermal battery cooling source is provided for removing heat from the condenser. The apparatus requires no external power and provides a cooling system for soldiers, race car drivers, police officers, firefighters, bomb squad technicians, and other personnel who may utilize protective clothing to work in hostile environments. An additional shield layer may simultaneously provide protection from discomfort, illness or injury due to harmful atmospheres, projectiles, edged weapons, impacts, explosions, heat, poisons, microbes, corrosive agents, or radiation, while simultaneously removing body heat from the wearer.

  4. Life cycle assessment of thermal Waste-to-Energy technologies: Review and recommendations

    DEFF Research Database (Denmark)

    Astrup, Thomas Fruergaard; Tonini, Davide; Turconi, Roberto

    2015-01-01

    -studies published in 136 peer-reviewed journal articles within 1995 and 2013. The studies were evaluated with respect to critical aspects such as: (i) goal and scope definitions (e.g. functional units, system boundaries, temporal and geographic scopes), (ii) detailed technology parameters (e.g. related to waste...... composition, technology, gas cleaning, energy recovery, residue management, and inventory data), and (iii) modeling principles (e.g. energy/mass calculation principles, energy substitution, inclusion of capital goods and uncertainty evaluation). Very few of the published studies provided full and transparent......Life cycle assessment (LCA) has been used extensively within the recent decade to evaluate the environmental performance of thermal Waste-to-Energy (WtE) technologies: incineration, co-combustion, pyrolysis and gasification. A critical review was carried out involving 250 individual case...

  5. The Effect of Thermal Cycling on Crystal-Liquid Separation During Lunar Magma Ocean Differentiation

    Science.gov (United States)

    Mills, Ryan D.

    2013-01-01

    Differentiation of magma oceans likely involves a mixture of fractional and equilibrium crystallization [1]. The existence of: 1) large volumes of anorthosite in the lunar highlands and 2) the incompatible- rich (KREEP) reservoir suggests that fractional crystallization may have dominated during differentiation of the Moon. For this to have occurred, crystal fractionation must have been remarkably efficient. Several authors [e.g. 2, 3] have hypothesized that equilibrium crystallization would have dominated early in differentiation of magma oceans because of crystal entrainment during turbulent convection. However, recent numerical modeling [4] suggests that crystal settling could have occurred throughout the entire solidification history of the lunar magma ocean if crystals were large and crystal fraction was low. These results indicate that the crystal size distribution could have played an important role in differentiation of the lunar magma ocean. Here, I suggest that thermal cycling from tidal heating during lunar magma ocean crystallization caused crystals to coarsen, leading to efficient crystal-liquid separation.

  6. Effect of Microstructural Evolution on Sagging Behavior of Cold-Rolled Aluminum Foil During the Brazing Thermal Cycle

    Science.gov (United States)

    Liu, Canwei; Xue, Xili; Chen, Xin; Li, Long; Xia, Chengdong; Zhong, Zhaojun; Zhou, Dejing

    2017-11-01

    Effect of microstructural evolution on sagging behavior of aluminum foil was investigated during the brazing thermal cycle. During the brazing thermal cycle, the sagging behavior consists of three stages: slight sagging stage, accelerative sagging stage and slow sagging stage. The sagging of cold-rolled aluminum foil mainly occurs in the accelerative sagging stage, which is governed by recovery under external stress in the sagging test. The coarse recrystallized grain is responsible for the slow sagging stage by reducing grain boundary sliding. Increasing cold-rolled reduction and addition of final annealing heat treatment can improve sagging resistance by shortening recovery process during the brazing thermal cycle. Dissolution of dispersoids has few effects on sagging deformation.

  7. Fundamental-frequency and load-varying thermal cycles effects on lifetime estimation of DFIG power converter

    DEFF Research Database (Denmark)

    Zhang, G.; Zhou, D.; Yang, J.

    2017-01-01

    In respect to a Doubly-Fed Induction Generator (DFIG) system, its corresponding time scale varies from microsecond level of power semiconductor switching to second level of the mechanical response. In order to map annual thermal profile of the power semiconductors, different approaches have been ...... adopted to handle the fundamental-frequency thermal cycles and load-varying thermal cycles. Their effects on lifetime estimation of the power device in the Back-to-Back (BTB) power converter are evaluated.......In respect to a Doubly-Fed Induction Generator (DFIG) system, its corresponding time scale varies from microsecond level of power semiconductor switching to second level of the mechanical response. In order to map annual thermal profile of the power semiconductors, different approaches have been...

  8. Effects of Thermal Cycling and Thermal Aging on the Hermeticity and Strength of Silver-Copper Oxide Air-Brazed Seals

    Energy Technology Data Exchange (ETDEWEB)

    Weil, K. Scott; Coyle, Christopher A.; Darsell, Jens T.; Xia, Gordon; Hardy, John S.

    2005-12-01

    Thermal cycle and exposure tests were conducted on ceramic-to-metal joints prepared by a new sealing technique. Known as reactive air brazing, this joining method is currently being considered for use in sealing various high-temperature solid-state electrochemical devices, including planar solid oxide fuel cells (pSOFC). In order to simulate a typical pSOFC application, test specimens were prepared by joining ceramic anode/electrolyte bilayers to washers, of the same composition as the common frame materials employed in pSOFC stacks, using a filler metal composed of 4mol% CuO in silver. The brazed samples were exposure tested at 750°C for 200, 400, and 800hrs in both simulated fuel and air environments and thermally cycled at rapid rate (75°C/min) between room temperature and 750°C for as many as fifty cycles. Subsequent joint strength testing and microstructural analysis indicated that the samples exposure tested in air displayed little degradation with respect to strength, hermeticity, or microstructure out to 800hrs of exposure. Those tested in fuel showed no change in rupture strength or loss in hermeticity after 800hrs of high-temperature exposure, but did undergo microstructural change due to the dissolution of hydrogen into the silver-based braze material. Air brazed specimens subjected to rapid thermal cycling exhibited no loss in joint strength or hermeticity, but displayed initial signs of seal delamination along the braze/electrolyte interface after 50 cycles.

  9. Effect of thermal cycle on the interfacial antiferromagnetic spin configuration and exchange bias in Ni-Mn-Sb alloy

    Directory of Open Access Journals (Sweden)

    R. L. Wang

    2012-09-01

    Full Text Available Effect of thermal cycle on the interfacial antiferromagnetic (AFM spin configuration and exchange bias in Ni50Mn36Sb14 alloy has been investigated. The results indicate thermal cycle can induce further martensitic transition from part of arrested FM phase to AFM phase, leading to the reconstruction of interfacial antiferromagnetic spin configuration. The shape of hysteresis loops at 5 K after cooling back can be tuned from a single-shifted loop to a nearly symmetric double-shifted loop gradually accompanied with exchange bias field increasing to peak value and then decreasing. The evolutions can be illustrated intuitively by a simple AFM bidomain model.

  10. Performance Evaluation of HP/ORC (Heat Pump/Organic Rankine Cycle) System with Optimal Control of Sensible Thermal Storage

    DEFF Research Database (Denmark)

    Do Carmo, Carolina Madeira Ramos; Dumont, Olivier; Nielsen, Mads Pagh

    2016-01-01

    energy in periods of no thermal energy demand and reverses the heat pump cycle to supply electrical power. A dynamic model based on empirical data of this system is used to determine the annual performance. Furthermore, this work assesses the benefits of different control strategies that address...... of the users. Results show that real load control logic can lessen the adverse effects of cycling in the compressor of the system as well as increase the thermal demand (up to 33%) and the electrical demand (max. 8.4%) covered by renewable energy (solar). However, the extension of these improvements is highly...

  11. Advanced Organic Vapor Cycles for Improving Thermal Conversion Efficiency in Renewable Energy Systems

    OpenAIRE

    Ho, Tony

    2012-01-01

    The Organic Flash Cycle (OFC) is proposed as a vapor power cycle that could potentially increase power generation and improve the utilization efficiency of renewable energy and waste heat recovery systems. A brief review of current advanced vapor power cycles including the Organic Rankine Cycle (ORC), the zeotropic Rankine cycle, the Kalina cycle, the transcritical cycle, and the trilateral flash cycle is presented. The premise and motivation for the OFC concept is that essentially by impro...

  12. The Effect of Thermal Cycling Treatments on the Thermal Stability and Mechanical Properties of a Ti-Based Bulk Metallic Glass Composite

    Directory of Open Access Journals (Sweden)

    Fan Bu

    2016-11-01

    Full Text Available The effect of thermal cycling treatments on the thermal stability and mechanical properties of a Ti48Zr20Nb12Cu5Be15 bulk metallic glass composite (BMGC has been investigated. Results show that moderate thermal cycles in a temperature range of −196 °C (cryogenic temperature, CT to 25 °C (room temperature, RT or annealing time at CT has not induced obvious changes of thermal stability and then it decreases slightly over critical thermal parameters. In addition, the dendritic second phases with a bcc structure are homogeneously embedded in the amorphous matrix; no visible changes are detected, which shows structural stability. Excellent mechanical properties as high as 1599 MPa yield strength and 34% plastic strain are obtained, and the yield strength and elastic modulus also increase gradually. The effect on the stability is analyzed quantitatively by crystallization kinetics and plastic-flow models, and indicates that the reduction of structural relaxation enthalpy, which is related to the degradation of spatial heterogeneity, reduces thermal stability but does not imperatively deteriorate the plasticity.

  13. Microleakage of self-etching primers after thermal and flexural load cycling.

    Science.gov (United States)

    Kubo, S; Yokota, H; Sata, Y; Hayashi, Y

    2001-06-01

    To evaluate the adhesive properties of a one-bottle self-etching primer system. 150 wedge-shaped cervical cavities on bovine teeth were restored with Clearfil Liner Bond 2 (LB), Clearfil Liner Bond 2V (LV) or Clearfil SE Bond (SE), according to the manufacturer's instructions. Twenty specimens of each adhesive system were finished 15 mins after light curing and 30 specimens were finished after a 24-hr storage period in water. From each group, 10 restorations were immediately immersed in 0.5% basic fuchsin solution and kept there for 24 hrs to examine microleakage. The other 10 restorations were thermocycled (5-60 degrees C, 15 s dwell time, 5,000 cycles), and then immersed in the dye solution. The remaining 10 specimens of the 24-hr storage group were subjected to flexural load cycling (0.5 mm labio-lingual displacement at the incisal edge, 10,000 cycles, 1 cps) prior to immersion in the dye solution. The data was analyzed using the Mann-Whitney U-test and the Kruskal-Wallis test. The tensile bond strengths of the adhesive systems to bovine enamel and dentin were also determined. The data was analyzed using the Student's t-test and ANOVA. In addition, SEM examinations were made to evaluate the effects of self-etching primers on enamel and dentin surfaces. LV and SE showed significantly better marginal sealing than LB (Pintegrity of SE did not deteriorate even after immediate finishing, thermal stresses or flexural loads. There were no significant differences in bond strengths among the adhesive systems tested. All adhesive systems showed similar bond strengths to enamel and dentin. The enamel etching patterns using LV and SE systems were obscure and difficult to assess. Although the smear plugs were not fully removed, no smear layer was observed on the treated dentin surfaces, regardless of the self-etching primer system used. Clearfil SE bond could possibly improve the clinical performance of cervical cavities.

  14. Fatigue life of fibre reinforced plastics at 295 K after thermal cycling between 295 K and 77 K

    Science.gov (United States)

    Belisario, G.; Caproni, F.; Marchetti, E.

    Results of low cycle three-point end fatigue tests at 295 K are reported. These were obtained from fibre reinforced plastics (FRP) flat specimens made of epoxy matrix reinforced with glass rovings only or glass rovings and Kevlar cloth. It is shown that previous thermal cycles between 295 K and 77 K exert an influence on the fatigue life as well on the acoustic emission results.

  15. The concentration parameter thermal microstresses as the thermophysical characteristics of two-phase materials

    Science.gov (United States)

    Kuanishev, V. T.; Sachkov, I. N.; Sorogin, I. G.; Sorogina, T. I.

    2017-11-01

    Thermal strength is one of the main thermophysical characteristics of structural materials. For homogeneous systems it is determined by the strength characteristics of the material. While for inhomogeneous systems, in particular, multiphase ones, it is necessary to consider the nature of the microstructure. Heat resistant real materials such as steels are known to be multi-phase systems. One of the mechanisms of their destruction is associated with the presence of propagating heat fluxes that generate thermal stresses. The aim of this paper is to evaluate the patterns of the formation of spatial distributions of thermal stresses in matrix systems of round inclusions characterized by different mutual disposition. The spatial distributions of thermal stresses in a two-phase material characterized by a matrix structure with round inclusions are investigated. For the numerical solution of the problem of stationary thermal conductivity the finite element method with discretization of the medium by triangular elements is used. It was found that at certain points in the medium the values of thermal stresses are ten times higher than the average for the material. It is shown that the spatial distribution and the local magnitude of the temperature gradient depend on the shape of the particles of the phase components and the values of their thermal conductivities. It is considered that the elastic moduli of inclusion and matrix differ little from each other.

  16. Continental growth and mantle hydration as intertwined feedback cycles in the thermal evolution of Earth

    Science.gov (United States)

    Höning, Dennis; Spohn, Tilman

    2016-06-01

    A model of Earth's continental coverage and mantle water budget is discussed along with its thermal evolution. The model links a thermal evolution model based on parameterized mantle convection with a model of a generic subduction zone that includes the oceanic crust and a sedimentary layer as carriers of water. Part of the subducted water is used to produce continental crust while the remainder is subducted into the mantle. The total length of the subduction zones is calculated from the total surface area of continental crust assuming randomly distributed continents. The mantle viscosity is dependent of temperature and the water concentration. Sediments are generated by continental crust erosion, and water outgassing at mid-oceanic ridges closes the water cycle. We discuss the strongly coupled, non-linear model using a phase plane defined by the continental coverage and mantle water concentration. Fixed points are found in the phase plane at which the rates of change of both variables are zero. These fixed points evolve with time, but in many cases, three fixed points emerge of which two are stable and an intermediate point is unstable with respect to continental coverage. With initial conditions from a Monte-Carlo scheme we calculate evolution paths in the phase plane and find a large spread of final states that all have a mostly balanced water budget. The present day observed 40% continental surface coverage is found near the unstable fixed point. Our evolution model suggests that Earth's continental coverage formed early and has been stable for at least 1.5 Gyr. The effect of mantle water regassing (and mantle viscosity depending on water concentration) is found to lower the present day mantle temperature by about 120 K, but the present day mantle viscosity is affected little. The water cycle thus complements the well-known thermostat effect of viscosity and mantle temperature. Our results further suggest that the biosphere could impact the feedback cycles by

  17. Fused deposition modeling (FDM) fabricated part behavior under tensile stress, thermal cycling, and fluid pressure

    Science.gov (United States)

    Hossain, Mohammad Shojib

    using visual feedback method led to an increase in UTS of 16% in XYZ, 7% in XZY, and 22% in ZXY. The FDM fabricated parts using PC were tested under thermal cycling of -30° C to 85° C. A series of experiments were performed (e.g., tensile test, deformation of fabricated part, glass transition measurement) to evaluate the possibility of FDM fabricated parts in the harsh environment (embedded electronics, wiring in automotive industry, etc.). The UTS results showed that the results were not significantly different using statistical analysis after 150 thermal cycles while average Young's modulus increased from 1389 MPa to 1469 MPa after 150 thermal cycles. The highest warping of the specimen was found to be 78 microm which was the result of continuous thermal expansion and contraction. A sealing algorithm was developed using LabVIEW and MATLAB programming. The LabVIEW program was developed to obtain the edge information of each layer of a 3D model part. The MATLAB programming was used to gather the output information from LabVIEW and calculate the suggested RW providing least amount of gap in between rasters and contours. As a result, each layer became sealed and was able to withstand air pressure within a pressure vessel. A test specimen was fabricated according to the developed sealing algorithm parameters and used to show entirely sealed walls capable of withstanding up to 138 kPa air pressure.

  18. Investigation of a putative nitrogen cycle in a subsurface radioactive thermal spring

    Science.gov (United States)

    Gerbl, Friedrich; Breitfuss, Angelika; Weidler, Gerhard; Stan-Lotter, Helga

    2010-05-01

    Background: Previous studies on the microbial diversity [1] of the slightly radioactive thermal springs near Bad Gastein, Salzburg, Austria, suggested the occurrence of a nitrogen cycle in this subterranean environment. Microcosm experiments were performed to prove if nitrogen compounds may be used as energy sources for certain members of the microbial community of this spring Methods: 2 x 25 l of thermal mineral water were sampled and filtered through a 0.22 µm Stericup (Millipore). Filters were excised and used as inocula for one microcosm. Stable isotope probing (SIP), was performed by using labeled nitrogen compounds to identify microorganisms, which were able to use nitrogen as the only energy source. 2 x 35 ml of natural grown biofilm were collected and used also as inocula for microcosms. Incubation was carried out as batch cultures in the dark at 30 °C or 40 °C, respectively. Two different types of media were used for incubation. Ammonium, nitrite and nitrate were measured 3-4 times a week. PH-value was also measured and adjusted to ca. 7.5 - 7.7 if necessary. DNA extraction was performed after 3 and 8 weeks of incubation, followed by an isopycnic centrifugation step. Clone libraries were performed only from microcosms incubated at 40 °C. To compare putative differences between the microbial communities at 30 °C with those at 40 °C, as well as the two different media, DGGE analyses were carried out. Results: A continuous decrease of the initial amount of ammonium was detected while the amounts of nitrite and nitrate increased simultaneously. No alterations of the initial amount of ammonium and nitrite or nitrate, could be detected with negative controls. Mass spectrometric measurements demonstrated that the extracted DNA was highly labeled. Phylogenetic analysis of DNA bands obtained from CsCl gradients led to differences in archaeal and bacterial communities of microcosms, which may reflect the different composition of media. Two of the archaeal

  19. High temperature, low cycle fatigue of copper-base alloys in argon. Part 3: Zirconium-copper; thermal-mechanical strain cycling, hold-time and notch fatigue results

    Science.gov (United States)

    Conway, J. B.; Stentz, R. H.; Berling, J. T.

    1973-01-01

    The low-cycle fatigue characteristics of smooth bar and notched bar specimens (hourglass shape) of zirconium-copper, 1/2 Hard, material (R-2 Series) were evaluated at room temperature in axial strain control. Over the fatigue life range from about 300 to 3000 cycles the ratio of fatigue life for smooth bar to fatigue life for notched bar remained constant at a value of about 6.0. Some additional hold-time data for the R-2 alloy tested in argon at 538 C are reported. An analysis of the relaxation data obtained in these hold-time tests is also reported and it is shown that these data yield a fairly consistent correlation in terms of instantaneous stress rate divided by instantaneous stress. Two thermal-mechanical strain cycling tests were also performed using a cyclic frequency of 4.5 cycles per hour and a temperature cycling interval from 260 to 538 C. The fatigue life values in these tests were noticeably lower than that observed in isothermal tests at 538 C.

  20. PEAR SHOOT SAWFLY (JANUS COMPRESSUS FABRICIUS) – LIFE CYCLE AND BIOLOGICAL AND MORPHOLOGICAL CHARACTERISTIC

    OpenAIRE

    Tihomir Validžić

    2014-01-01

    The aim of the thesis was to investigate life cycle, biological and morphological characteristics of pear shoot sawfly (Janus compressus Fabricius, Hymenoptera Cephidae), furthermore to identify natural enemies in order to protect pear from this pest. The trial was conducted in the period of three years: 2010, 2011 and 2012 in pear orchards at five localities. Monitoring of adult sawfly was done by yellow sticky traps. Laboratory research was done at the Faculty of Agriculture, Department of ...

  1. The effect of thermal cycling on the structure and properties of a Co, Cr, Ni-TaC directionally solidified eutectic composite

    Science.gov (United States)

    Dunlevey, F. M.; Wallace, J. F.

    1973-01-01

    The effect of thermal cycling on the structure and properties of a cobalt, chromium, nickel, tantalum carbide directionally solidified eutectic composite is reported. It was determined that the stress rupture properties of the alloy were decreased by the thermal cycling. The loss in stress rupture properties varied with the number of cycles with the loss in properties after about 200 cycles being relatively high. The formation of serrations and the resulting changes in the mechanical properties of the material are discussed.

  2. Estimation of Soil-Water Characteristic Curves in Multiple-Cycles Using Membrane and TDR System

    Science.gov (United States)

    Hong, Won-Taek; Jung, Young-Seok; Kang, Seonghun; Lee, Jong-Sub

    2016-01-01

    The objective of this study is to estimate multiple-cycles of the soil-water characteristic curve (SWCC) using an innovative volumetric pressure plate extractor (VPPE), which is incorporated with a membrane and time domain reflectometry (TDR). The pressure cell includes the membrane to reduce the experimental time and the TDR probe to automatically estimate the volumetric water content. For the estimation of SWCC using the VPPE system, four specimens with different grain size and void ratio are prepared. The volumetric water contents of the specimens according to the matric suction are measured by the burette system and are estimated in the TDR system during five cycles of SWCC tests. The volumetric water contents estimated by the TDR system are almost identical to those determined by the burette system. The experimental time significantly decreases with the new VPPE. The hysteresis in the SWCC is largest in the first cycle and is nearly identical after 1.5 cycles. As the initial void ratio decreases, the air entry value increases. This study suggests that the new VPPE may effectively estimate multiple-cycles of the SWCC of unsaturated soils. PMID:28774139

  3. Ocean Thermal Energy Conversion Life Cycle Cost Assessment, Final Technical Report, 30 May 2012

    Energy Technology Data Exchange (ETDEWEB)

    Martel, Laura [Lockheed Martin, Manassas, VA (United States); Smith, Paul [John Halkyard and Associates: Glosten Associates, Houston, TX (United States); Rizea, Steven [Makai Ocean Engineering, Waimanalo, HI (United States); Van Ryzin, Joe [Makai Ocean Engineering, Waimanalo, HI (United States); Morgan, Charles [Planning Solutions, Inc., Vancouver, WA (United States); Noland, Gary [G. Noland and Associates, Inc., Pleasanton, CA (United States); Pavlosky, Rick [Lockheed Martin, Manassas, VA (United States); Thomas, Michael [Lockheed Martin, Manassas, VA (United States); Halkyard, John [John Halkyard and Associates: Glosten Associates, Houston, TX (United States)

    2012-05-30

    The Ocean Thermal Energy Conversion (OTEC) Life Cycle Cost Assessment (OLCCA) is a study performed by members of the Lockheed Martin (LM) OTEC Team under funding from the Department of Energy (DOE), Award No. DE-EE0002663, dated 01/01/2010. OLCCA objectives are to estimate procurement, operations and maintenance, and overhaul costs for two types of OTEC plants: -Plants moored to the sea floor where the electricity produced by the OTEC plant is directly connected to the grid ashore via a marine power cable (Grid Connected OTEC plants) -Open-ocean grazing OTEC plant-ships producing an energy carrier that is transported to designated ports (Energy Carrier OTEC plants) Costs are developed using the concept of levelized cost of energy established by DOE for use in comparing electricity costs from various generating systems. One area of system costs that had not been developed in detail prior to this analysis was the operations and sustainment (O&S) cost for both types of OTEC plants. Procurement costs, generally referred to as capital expense and O&S costs (operations and maintenance (O&M) costs plus overhaul and replacement costs), are assessed over the 30 year operational life of the plants and an annual annuity calculated to achieve a levelized cost (constant across entire plant life). Dividing this levelized cost by the average annual energy production results in a levelized cost of electricity, or LCOE, for the OTEC plants. Technical and production efficiency enhancements that could result in a lower value of the OTEC LCOE were also explored. The thermal OTEC resource for Oahu, Hawaii and projected build out plan were developed. The estimate of the OTEC resource and LCOE values for the planned OTEC systems enable this information to be displayed as energy supplied versus levelized cost of the supplied energy; this curve is referred to as an Energy Supply Curve. The Oahu Energy Supply Curve represents initial OTEC deployment starting in 2018 and demonstrates the

  4. Measurements of thermal characteristics in silicon germanium un-cooled micro-bolometers

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, Mario; Torres, Alfonso; Kosarev, Andrey [National Institute for Astrophysics, Optics and Electronics, P.O. Box 51 and 216, Z.P. 7200 Puebla (Mexico); Ambrosio, Roberto; Mireles, Jose [Universidad Autonoma de Ciudad Juarez, Electrical Department, Av. Del Charro 450 N, Z.P. 32310, C. J., Chihuahua (Mexico); Garcia, Maria [Benemerita Universidad Autonoma de Puebla, Physics Department, Av. San Claudio S/N Z.P. 72570 Puebla (Mexico)

    2010-04-15

    We present a study of the thermal characteristics of an infrared detector (un-cooled micro-bolometer), based on an amorphous silicon germanium film (a-Si{sub x}Ge{sub y}:H), deposited by plasma at low temperature ({proportional_to} 300 C) and compatible with the standard CMOS technology. These films have been studied due to their high performance characteristics as high activation energy (E{sub a}{approx} 0.37 eV), high temperature coefficient of resistance (TCR{approx} -0.047 K{sup -1}) and moderate room temperature conductivity ({sigma}{sub RT}{approx} 2x10{sup -5}{omega} cm), which provides a moderate pixel resistance (R{sub cell}{approx}3.5x10{sup 8}{omega}). We have used two simple methods to calculate the thermal characteristics of the micro-bolometer. The thermal conductance (G{sub th}) has been obtained from the electrical I(U) characteristics in the range where self heating due to bias is not presented. The temperature dependence of the electrical resistance and as well the temperature dependence of the thermal resistance have been obtained by measuring the I(U) characteristics in the device at different temperature values. Finally the results of both methods have been compared. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Study of the quantitative assessment method for high-cycle thermal fatigue of a T-pipe under turbulent fluid mixing based on the coupled CFD-FEM method and the rainflow counting method

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y.; Lu, T., E-mail: likesurge@sina.com

    2016-12-01

    Highlights: • Two characteristic parameters of the temperature fluctuations are used for qualitative analysis. • A quantitative assessment method for high-cycle thermal fatigue of a T-pipe is proposed. • The time-dependent curves for the temperature and thermal stress are not always “in-phase”. • Large magnitude of thermal stresses may not mean large number of fatigue cycles. • The normalized fatigue damage rate and normalized RMS temperature are positively related. - Abstract: With the development of nuclear power and nuclear power safety, high-cycle thermal fatigue of the pipe structures induced by the flow and heat transfer of the fluid in pipes have aroused more and more attentions. Turbulent mixing of hot and cold flows in a T-pipe is a well-recognized source of thermal fatigue in piping system, and thermal fatigue is a significant long-term degradation mechanism. It is not an easy work to evaluate thermal fatigue of a T-pipe under turbulent flow mixing because of the thermal loads acting at fluid–structure interface of the pipe are so complex and changeful. In this paper, a one-way Computational Fluid Dynamics-Finite Element Method (CFD-FEM method) coupling based on the ANSYS Workbench 15.0 software has been developed to calculate transient thermal stresses with the temperature fields of turbulent flow mixing, and thermal fatigue assessment has been carried out with this obtained fluctuating thermal stresses by programming in the software platform of Matlab based on the rainflow counting method. In the thermal analysis, the normalized mean temperatures and the normalized root mean square (RMS) temperatures are obtained and compared with the experiment of the test case from the Vattenfall benchmark facility to verify the accuracy of the CFD calculation and to determine the position which thermal fatigue is most likely to occur in the T-junction. Besides, more insights have been obtained in the coupled CFD-FEM analysis and the thermal fatigue

  6. The Philosophy which underlies the structural tests of a supersonic transport aircraft with particular attention to the thermal cycle

    Science.gov (United States)

    Ripley, E. L.

    1972-01-01

    The information presented is based on data obtained from the Concorde. Much of this data also applies to other supersonic transport aircraft. The design and development of the Concorde is a joint effort of the British and French, and the structural test program is shared, as are all the other activities. Vast numbers of small specimens have been tested to determine the behavior of the materials used in the aircraft. Major components of the aircraft structure, totalling almost a complete aircraft, have been made and are being tested to help the constructors in each country in the design and development of the structure. Tests on two complete airframes will give information for the certification of the aircraft. A static test was conducted in France and a fatigue test in the United Kingdom. Fail-safe tests are being made to demonstrate the crack-propagation characteristics of the structure and its residual strength. Aspects of the structural test program are described in some detail, dealing particularly with the problems associated with the thermal cycle. The biggest of these problems is the setting up of the fatigue test on the complete airframe; therefore, this is covered more extensively with a discussion about how the test time can be shortened and with a description of the practical aspects of the test.

  7. A Technique for Mitigating Thermal Stress and Extending Life Cycle of Power Electronic Converters Used for Wind Turbines

    Directory of Open Access Journals (Sweden)

    Canras Batunlu

    2015-11-01

    Full Text Available Over the last two decades, various models have been developed to assess and improve the reliability of power electronic conversion systems (PECs with a focus on those used for wind turbines. However, only few studies have dealt with mitigating the PECs thermo-mechanical effects on their reliability taking into account variations in wind characteristics. This work critically investigates this issue and attempts to offer a mitigating technique by, first, developing realistic full scale (FS and partial scale (PS induction generator models combined with two level back-to-back PECs. Subsequently, deriving a driving algorithm, which reduces PEC’s operating temperature by controlling its switching patterns. The developed switching procedure ensures minimum temperature fluctuations by adapting the variable DC link and system’s frequency of operation. It was found for both FS and PS topologies, that the generator side converters have higher mean junction temperatures where the grid side ones have more fluctuations on their thermal profile. The FS and PS cycling temperatures were reduced by 12 °C and 5 °C, respectively. Moreover, this led to a significant improvement in stress; approximately 27 MPa stress reduction for the FS induction generator PEC.

  8. Evaluation of roughness and micromorphology of epoxy paint on cobalt-chromium alloy before and after thermal cycling

    Directory of Open Access Journals (Sweden)

    Alessandra Cardoso da Silva Nascimento

    2013-04-01

    Full Text Available It has been suggested that the epoxy paint used to coat metal substrates in industrial electrostatic painting applications could also be used to mask metal clasps in removable dental prostheses (RDP. The purpose of this study was to evaluate both the influence of thermal cycling and the in vitro roughness of a surface after application of epoxy paint, as well as to assess the micromorphology of a cobalt-chromium (CoCr based metal structure. Sixty test specimens were fabricated from a CoCr alloy. The specimens were separated into three groups (n = 20 according to surface treatment: Group 1 (Pol - polished with abrasive stone and rubbers; Group 2 (Pol+Epo - polished and coated with epoxy paint; Group 3 (Epo - air-abraded with aluminum oxide particles and coated with epoxy paint. The surface roughness was evaluated before and after 1000 thermal cycles (5°C and 50°C. The surface micromorphology was verified by scanning electron microscopy (SEM. The two-way repeated measures ANOVA showed significant differences among surface treatments (p < 0.0001, but no difference was found before and after thermal cycling (p = 0.6638. The CoCr-based metal alloy surfaces treated with epoxy paint (Groups 2 and 3 were rougher than the surfaces that were only polished (Group 1. Thermal cycling did not influence surface roughness, or lead to chipping or detachment of the epoxy paint.

  9. Influence of thermal and mechanical cycling on the flexural strength of ceramics with titanium or gold alloy frameworks

    NARCIS (Netherlands)

    Oyafuso, Denise Kanashiro; Ozcan, Mutlu; Bottino, Marco Antonio; Itinoche, Marcos Koiti

    Objectives. The aim of this study was to evaluate the effect of thermal and mechanical cycling alone or in combination, on the flexural strength of ceramic and metallic frameworks cast in gold alloy or titanium. Methods. Metallic frameworks (25 mm x 3 mm x 0.5 mm) (N = 96) cast in gold alloy or

  10. Measured thermal and fast neutron fluence rates for ATF-1 holders during ATR cycle 158B/159A

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Larry Don [Idaho National Lab. (INL), Idaho Falls, ID (United States); Miller, David Torbet [Idaho National Lab. (INL), Idaho Falls, ID (United States); Walker, Billy Justin [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-11-01

    This report contains the thermal (2200 m/s) and fast (E>1MeV) neutron fluence rate data for the ATF-1 holders located in core for ATR Cycle 158B/159A which were measured by the Radiation Measurements Laboratory (RML).

  11. Effect of bonding and bakeout thermal cycles on the properties of copper alloys irradiated at 350 degrees C

    DEFF Research Database (Denmark)

    Singh, B.N.; Edwards, D.J.; Eldrup, Morten Mostgaard

    2001-01-01

    Screening experiments were carried out to determine the effect of bonding and bakeout thermal cycles on microstructure, mechanical properties and electrical resistivity of the oxide dispersion strengthened (GlidCop, CuAl-25) and the precipitation hardened (CuCrZr, CuNiBe) copper alloys. Tensile...

  12. Characterization of Ternary NiTiPd High-Temperature Shape-Memory Alloys under Load-Biased Thermal Cycling

    Science.gov (United States)

    Bigelow, Glen S.; Padula, Santo A.; Noebe, Ronald D.; Garg, Anita; Gaydosh, Darrell

    2010-01-01

    While NiTiPd alloys have been extensively studied for proposed use in high-temperature shape-memory applications, little is known about the shape-memory response of these materials under stress. Consequently, the isobaric thermal cyclic responses of five (Ni,Pd)49.5Ti50.5 alloys with constant stoichiometry and Pd contents ranging from 15 to 46 at. pct were investigated. From these tests, transformation temperatures, transformation strain (which is proportional to work output), and unrecovered strain per cycle (a measure of dimensional instability) were determined as a function of stress for each alloy. It was found that increasing the Pd content over this range resulted in a linear increase in transformation temperature, as expected. At a given stress level, work output decreased while the amount of unrecovered strain produced during each load-biased thermal cycle increased with increasing Pd content, during the initial thermal cycles. However, continued thermal cycling at constant stress resulted in a saturation of the work output and nearly eliminated further unrecovered strain under certain conditions, resulting in stable behavior amenable to many actuator applications.

  13. Effects of thermal hydrolysis temperature on physical characteristics of municipal sludge.

    Science.gov (United States)

    Feng, Guohong; Guo, Yabing; Tan, Wei

    2015-01-01

    Effects of thermal hydrolysis temperature on the physical properties of municipal sludge was further studied by a series of experiments. There was a decrease in bound water content with an increase in hydrolysis temperature, while there was an increase in pH at temperatures below 120 °C, and a decrease at temperatures exceeding 120 °C. An analysis of settleability, centrifugation and vacuum filtration of the treated sludge indicated that the threshold temperature was 120 °C, which was the same as the temperature for the bound water content and particle size. In addition, raw sludge with a solids content of 100 g/L, exhibited significant non-Newtonian fluid characteristics. At thermal hydrolysis temperatures exceeding 120 °C, non-Newtonian fluid characteristics including liquid and solid characteristics were significantly weakened. The consistency index (k) decreased from 5.90 Pa·s to 0.068 Pa·s, while the flow index (n) increased from 0.31 to 0.74, suggesting that thermal hydrolysis sludge was much closer to Newtonian fluids compared to raw sludge. Modification of bound water content, particle size and viscosity with hydrolysis temperature, revealed the nature of improved dewaterability by thermal hydrolysis. The fractal dimension of the sludge floc increased from 2.74 to 2.90, meaning that the floc became more compact after thermal hydrolysis.

  14. Thermally moderated hollow fiber sorbent modules in rapidly cycled pressure swing adsorption mode for hydrogen purification

    KAUST Repository

    Lively, Ryan P.

    2012-10-01

    We describe thermally moderated multi-layered pseudo-monolithic hollow fiber sorbents entities, which can be packed into compact modules to provide small-footprint, efficient H2 purification/CO2 removal systems for use in on-site steam methane reformer product gas separations. Dual-layer hollow fibers are created via dry-jet, wet-quench spinning with an inner "active" core of cellulose acetate (porous binder) and zeolite NaY (69 wt% zeolite NaY) and an external sheath layer of pure cellulose acetate. The co-spun sheath layer reduces the surface porosity of the fiber and was used as a smooth coating surface for a poly(vinyl-alcohol) post-treatment, which reduced the gas permeance through the fiber sorbent by at least 7 orders of magnitude, essentially creating an impermeable sheath layer. The interstitial volume between the individual fibers was filled with a thermally-moderating paraffin wax. CO2 breakthrough experiments on the hollow fiber sorbent modules with and without paraffin wax revealed that the "passively" cooled paraffin wax module had 12.5% longer breakthrough times than the "non-isothermal" module. The latent heat of fusion/melting of the wax offsets the released latent heat of sorption/desorption of the zeolites. One-hundred rapidly cycled pressure swing adsorption cycles were performed on the "passively" cooled hollow fiber sorbents using 25 vol% CO2/75 vol% He (H2 surrogate) at 60 °C and 113 psia, resulting in a product purity of 99.2% and a product recovery of 88.1% thus achieving process conditions and product quality comparable to conventional pellet processes. Isothermal and non-isothermal dynamic modeling of the hollow fiber sorbent module and a traditional packed bed using gPROMS® indicated that the fiber sorbents have sharper fronts (232% sharper) and longer adsorbate breakthrough times (66% longer), further confirming the applicability of the new fiber sorbent approach for H2 purification. © 2012, Hydrogen Energy Publications, LLC

  15. Micro solid oxide fuel cell fabricated on porous stainless steel: a new strategy for enhanced thermal cycling ability

    Science.gov (United States)

    Kim, Kun Joong; Park, Byung Hyun; Kim, Sun Jae; Lee, Younki; Bae, Hongyeul; Choi, Gyeong Man

    2016-01-01

    Miniaturized solid oxide fuel cells (micro-SOFCs) are being extensively studied as a promising alternative to Li batteries for next generation portable power. A new micro-SOFC is designed and fabricated which shows enhanced thermal robustness by employing oxide-based thin-film electrode and porous stainless steel (STS) substrate. To deposit gas-tight thin-film electrolyte on STS, nano-porous composite oxide is proposed and applied as a new contact layer on STS. The micro-SOFC fabricated on composite oxide- STS dual layer substrate shows the peak power density of 560 mW cm−2 at 550 °C and maintains this power density during rapid thermal cycles. This cell may be suitable for portable electronic device that requires high power-density and fast thermal cycling. PMID:26928921

  16. Numerical Calculation of Transient Thermal Characteristics in Gas-Insulated Transmission Lines

    Directory of Open Access Journals (Sweden)

    Hongtao Li

    2013-11-01

    Full Text Available For further knowledge of the thermal characteristics in gas-insulated transmission lines (GILs installed above ground, a finite-element model coupling fluid field and thermal field is established, in which the corresponding assumptions and boundary conditions are given.  Transient temperature rise processes of the GIL under the conditions of variable ambient temperature, wind velocity and solar radiation are respectively investigated. Equivalent surface convective heat transfer coefficient and heat flux boundary conditions are updated in the analysis process. Unlike the traditional finite element methods (FEM, the variability of the thermal properties with temperature is considered. The calculation results are validated by the tests results reported in the literature. The conclusion provides method and theory basis for the knowledge of transient temperature rise characteristics of GILs in open environment.

  17. The Thermal Performance and Air Leakage Characteristics of Six Log Homes in Idaho.

    Energy Technology Data Exchange (ETDEWEB)

    Roos, Carolyn; Eklund, Ken; Baylon, David

    1993-08-01

    The thermal performance and air leakage characteristics of four electrically heated log houses located in Idaho are summarized. The air leakage and construction characteristics of two additional log homes are also examined. The energy consumption of the four homes was submetered at weekly reporting intervals for up to 16 months. Blower door tests and site audits were performed. In addition, conditions at two of these homes, including heat flux through the log walls, indoor and outdoor temperatures, solar flux and envelope tightness, were measured in detail over several days during winter conditions. The energy use and thermal performance of these two homes were then modeled using SUNCODE-PC, an hourly thermal simulation program employing a finite difference technique.

  18. Investigation on the Interface Characteristics of the Thermal Barrier Coating System through Flat Cylindrical Indenters

    Directory of Open Access Journals (Sweden)

    Shifeng Wen

    2014-01-01

    Full Text Available Thermal barrier coating (TBC systems are highly advanced material systems and usually applied to insulate components from large and prolonged heat loads by utilizing thermally insulating materials. In this study, the characteristics of the interface of thermal barrier coating systems have been simulated by the finite-element method (FEM. The emphasis was put on the stress distribution at the interface which is beneath the indenter. The effect of the interface roughness, the thermally grown oxide (TGO layer's thickness, and the modulus ratio (η of the thin film with the substrate has been considered. Finite-element results showed that the influences of the interface roughness and the TGO layer's thickness on stress distribution were important. At the same time, the residual stress distribution has been investigated in detail.

  19. Breathing thermal manikins for indoor environment assessment: important characteristics and requirements

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor

    2004-01-01

    and perceived air quality by means of breathing thermal manikins have been made as well. In order to perform accurate measurements and realistic evaluation and assessment, the design and characteristics of a manikin must comply with certain requirements. The most important of these, such as number, size...

  20. A Data Analysis Technique to Estimate the Thermal Characteristics of a House

    NARCIS (Netherlands)

    Tabatabaei, S.; van der Ham, Wim; Klein, Michel C. A.; Treur, Jan

    2017-01-01

    Almost one third of the energy is used in the residential sector, and space heating is the largest part of energy consumption in our houses. Knowledge about the thermal characteristics of a house can increase the awareness of homeowners about the options to save energy, for example by showing that

  1. A review on the thermal hydraulic characteristics of the air-cooled ...

    Indian Academy of Sciences (India)

    Home; Journals; Sadhana; Volume 40; Issue 3. A review on the thermal hydraulic characteristics of the air-cooled heat exchangers in forced convection. Ankur Kumar Jyeshtharaj B Joshi Arun K Nayak Pallippattu K Vijayan. Section I – Fluid Mechanics and Fluid Power (FMFP) Volume 40 Issue 3 May 2015 pp 673-755 ...

  2. FORMING OF MECHANICAL CHARACTERISTICS OF THE SLUGS OF TITANIC ALLOY BT23 AT THERMAL TREATMENT

    Directory of Open Access Journals (Sweden)

    V. N. Fedulov

    2005-01-01

    Full Text Available Тhе changings of the initial plate structure of alloy BT23 at running of high-temperature thermal treatment of large-sized slugs with heating up to 650- 950 eC and cooling on air and in water and their influence on forming of complex of mechanical characteristics are examined.

  3. Nanodomain Engineered (K, Na)NbO3 Lead-Free Piezoceramics: Enhanced Thermal and Cycling Reliabilities

    DEFF Research Database (Denmark)

    Yao, Fang-Zhou; Wang, Ke; Cheng, Li-Qian

    2015-01-01

    temperature fluctuation and electrical fatigue cycling. It was found that the piezoelectric coefficient d33 is temperature independent under 4 kV/mm, which can be attributed to enhanced thermal stability of electric field engineered domain configuration; whereas the electric field induced strain exhibits......The growing environmental concerns have been pushing the development of viable green alternatives for lead-based piezoceramics to be one of the priorities in functional ceramic materials. A polymorphic phase transition has been utilized to enhance piezoelectric properties of lead-free (K, Na)NbO3...... excellent fatigue resistance up to 107 sesquipolar cycles. These findings render the current material an unprecedented opportunity for actuator applications demanding improved thermal and cycling reliabilities....

  4. Energy performance and economic evaluation of heat pump/organic rankine cycle system with sensible thermal storage

    DEFF Research Database (Denmark)

    Carmo, Carolina; Dumont, Olivier; Nielsen, Mads Pagh

    2016-01-01

    that consists of a ground-source heat pump with possibility of reversing operation as an ORC power cycle combined with solar heating in a single-family building is introduced. The ORC mode enables the use of solar energy in periods of no heat energy demand and reverses the heat pump cycle to supply electrical......-life conditions knowledge, the paper considers two different sensible energy storage (TES) configurations for the reversible heat pump/organic Rankine cycle (HP/ORC) system: a buffer tank for both space heating and domestic hot water and a hot water storage tank used exclusively for domestic hot water......The interaction between electrical and thermal energy demands represent a potential area for balancing supply and demand that could contribute to the integration of intermittent renewables in energy systems. To enable the interaction between thermal and electric energy, an innovative concept...

  5. Energy Performance and Economic Evaluation of Heat Pump/Organic Rankine Cycle System with Sensible Thermal Storage

    DEFF Research Database (Denmark)

    Carmo, C.; Dumont, O.; Nielsen, M. P.

    2016-01-01

    that consists of a ground-source heat pump with possibility of reversing operation as an ORC power cycle combined with solar heating in a single-family building is introduced. The ORC mode enables the use of solar energy in periods of no heat energy demand and reverses the heat pump cycle to supply electrical......-life conditions knowledge, the paper considers two different sensible energy storage (TES) configurations for the reversible heat pump/organic Rankine cycle (HP/ORC) system: a buffer tank for both space heating and domestic hot water and a hot water storage tank used exclusively for domestic hot water......The interaction between electrical and thermal energy demands represent a potential area for balancing supply and demand that could contribute to the integration of intermittent renewables in energy systems. To enable the interaction between thermal and electric energy, an innovative concept...

  6. Energetic and exergetic analysis of Rankine cycles for solar power plants with parabolic trough and thermal storage

    Directory of Open Access Journals (Sweden)

    Cenuşă Victor-Eduard

    2016-01-01

    Full Text Available The paper analyzes the “secondary” circuit (for thermodynamic conversion of a Concentrated Solar Power (CSP plant with thermodynamic cycle, whose mirrors field supplies a thermal power, averaged over a sunny day, of about 100 MW heat. We study the case of parabolic trough solar collector using silicone oil in the “primary” circuit, which limits the peak temperature below 400 °C. The “primary” circuit uses thermal storage, allowing a delay between the power generation in rapport with the solar energy capture. We choose a water-steam cycle, type Hirn. For increasing its efficiency, it has regenerative feed water preheating and steam reheating. We compared, energetic and exergetic, two types of cycles, using a numerical model with iterative structure, developed by the authors. The results showed that the simplified design achieves practically the same thermodynamic performances with the advanced one.

  7. Numerical Investigation of Characteristic of Anisotropic Thermal Conductivity of Natural Fiber Bundle with Numbered Lumens

    Directory of Open Access Journals (Sweden)

    Guan-Yu Zheng

    2014-01-01

    Full Text Available Natural fiber bundle like hemp fiber bundle usually includes many small lumens embedded in solid region; thus, it can present lower thermal conduction than that of conventional fibers. In the paper, characteristic of anisotropic transverse thermal conductivity of unidirectional natural hemp fiber bundle was numerically studied to determine the dependence of overall thermal property of the fiber bundle on that of the solid region phase. In order to efficiently predict its thermal property, the fiber bundle was embedded into an imaginary matrix to form a unit composite cell consisting of the matrix and the fiber bundle. Equally, another unit composite cell including an equivalent solid fiber was established to present the homogenization of the fiber bundle. Next, finite element thermal analysis implemented by ABAQUS was conducted in the two established composite cells by applying proper thermal boundary conditions along the boundary of unit cell, and influences of the solid region phase and the equivalent solid fiber on the composites were investigated, respectively. Subsequently, an optional relationship of thermal conductivities of the natural fiber bundle and the solid region was obtained by curve fitting technique. Finally, numerical results from the obtained fitted curves were compared with the analytic Hasselman-Johnson’s results and others to verify the present numerical model.

  8. Effects of Hygrothermal Cycling on the Chemical, Thermal, and Mechanical Properties of 862/W Epoxy Resin

    Science.gov (United States)

    Miller, Sandi G.; Roberts, Gary D.; Copa, Christine C.; Bail, Justin L.; Kohlman, Lee W.; Binienda, Wieslaw K.

    2011-01-01

    The hygrothermal aging characteristics of an epoxy resin were characterized over 1 year, which included 908 temperature and humidity cycles. The epoxy resin quickly showed evidence of aging through color change and increased brittleness. The influence of aging on the material s glass transition temperature (Tg) was evaluated by Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). The Tg remained relatively constant throughout the year long cyclic aging profile. The chemical composition was monitored by Fourier Transform Infrared Spectroscopy (FTIR) where evidence of chemical aging and advancement of cure was noted. The tensile strength of the resin was tested as it aged. This property was severely affected by the aging process in the form of reduced ductility and embrittlement. Detailed chemical evaluation suggests many aging mechanisms are taking place during exposure to hygrothermal conditions. This paper details the influence of processes such as: advancement of cure, chemical degradation, and physical aging on the chemical and physical properties of the epoxy resin.

  9. Multi-parameter fibre Bragg grating sensor-array for thermal vacuum cycling test

    Science.gov (United States)

    Cheng, L.; Ahlers, B.; Toet, P.; Casarosa, G.; Appolloni, M.

    2017-11-01

    strain transducer to generate strain via a dedicated feed through in the chamber. Thermocouples are used to log the temperature for comparison to the temperature FBG sensor. Extreme temperature ranges from -150°C and +70°C at a pressure down to 10-4 Pa (10-6 mbar) are covered as well as testing under ambient conditions. In total five thermal cycles during a week test are performed. The FBG temperature sensor test results performed in the ESA/ESTEC TV chamber reveal high reproducibility (within 1 °C) within the test temperature range without any evidence of hysteresis. Differences are detected to the previous calibration curve. Investigation is performed to find the cause of the discrepancy. Differences between the test set-ups are identified. Equipment of the TNO test is checked and excluded to be the cause. Additional experiments are performed. The discrepancy is most likely caused by a 'thermal shock' due to rapid cooling down to LN2 temperature, which results in a wavelength shift. Test data of the FBG strain sensor is analysed. The read-out of the FBG strain sensor varies with the temperature during the test. This can be caused by temperature induced changes in the mechanical setup (fastening of the mechanical parts) or impact of temperature to the mechanical strain transfer to the FBG. Improvements are identified and recommendations given for future activities.

  10. Structure optimisation by thermal cycling for the hydrophobic-polar lattice model of protein folding

    Science.gov (United States)

    Günther, Florian; Möbius, Arnulf; Schreiber, Michael

    2017-03-01

    The function of a protein depends strongly on its spatial structure. Therefore the transition from an unfolded stage to the functional fold is one of the most important problems in computational molecular biology. Since the corresponding free energy landscapes exhibit huge numbers of local minima, the search for the lowest-energy configurations is very demanding. Because of that, efficient heuristic algorithms are of high value. In the present work, we investigate whether and how the thermal cycling (TC) approach can be applied to the hydrophobic-polar (HP) lattice model of protein folding. Evaluating the efficiency of TC for a set of two- and three-dimensional examples, we compare the performance of this strategy with that of multi-start local search (MSLS) procedures and that of simulated annealing (SA). For this aim, we incorporated several simple but rather efficient modifications into the standard procedures: in particular, a strong improvement was achieved by also allowing energy conserving state modifications. Furthermore, the consideration of ensembles instead of single samples was found to greatly improve the efficiency of TC. In the framework of different benchmarks, for all considered HP sequences, we found TC to be far superior to SA, and to be faster than Wang-Landau sampling.

  11. The Seasonal Cycle of Water Vapour on Mars from Assimilation of Thermal Emission Spectrometer Data

    Science.gov (United States)

    Steele, Liam J.; Lewis, Stephen R.; Patel, Manish R.; Montmessin, Franck; Forget, Francois; Smith, Michael D.

    2014-01-01

    We present for the first time an assimilation of Thermal Emission Spectrometer (TES) water vapour column data into a Mars global climate model (MGCM). We discuss the seasonal cycle of water vapour, the processes responsible for the observed water vapour distribution, and the cross-hemispheric water transport. The assimilation scheme is shown to be robust in producing consistent reanalyses, and the global water vapour column error is reduced to around 2-4 pr micron depending on season. Wave activity is shown to play an important role in the water vapour distribution, with topographically steered flows around the Hellas and Argyre basins acting to increase transport in these regions in all seasons. At high northern latitudes, zonal wavenumber 1 and 2 stationary waves during northern summer are responsible for spreading the sublimed water vapour away from the pole. Transport by the zonal wavenumber 2 waves occurs primarily to the west of Tharsis and Arabia Terra and, combined with the effects of western boundary currents, this leads to peak water vapour column abundances here as observed by numerous spacecraft. A net transport of water to the northern hemisphere over the course of one Mars year is calculated, primarily because of the large northwards flux of water vapour which occurs during the local dust storm around L(sub S) = 240-260deg. Finally, outlying frost deposits that surround the north polar cap are shown to be important in creating the peak water vapour column abundances observed during northern summer.

  12. Life cycle assessment of thermal waste-to-energy technologies: review and recommendations.

    Science.gov (United States)

    Astrup, Thomas Fruergaard; Tonini, Davide; Turconi, Roberto; Boldrin, Alessio

    2015-03-01

    Life cycle assessment (LCA) has been used extensively within the recent decade to evaluate the environmental performance of thermal Waste-to-Energy (WtE) technologies: incineration, co-combustion, pyrolysis and gasification. A critical review was carried out involving 250 individual case-studies published in 136 peer-reviewed journal articles within 1995 and 2013. The studies were evaluated with respect to critical aspects such as: (i) goal and scope definitions (e.g. functional units, system boundaries, temporal and geographic scopes), (ii) detailed technology parameters (e.g. related to waste composition, technology, gas cleaning, energy recovery, residue management, and inventory data), and (iii) modeling principles (e.g. energy/mass calculation principles, energy substitution, inclusion of capital goods and uncertainty evaluation). Very few of the published studies provided full and transparent descriptions of all these aspects, in many cases preventing an evaluation of the validity of results, and limiting applicability of data and results in other contexts. The review clearly suggests that the quality of LCA studies of WtE technologies and systems including energy recovery can be significantly improved. Based on the review, a detailed overview of assumptions and modeling choices in existing literature is provided in conjunction with practical recommendations for state-of-the-art LCA of Waste-to-Energy. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Assessment of Accrued Damage and Remaining Useful Life in Leadfree Electronics Subjected to Multiple Thermal Environments of Thermal Aging and Thermal Cycling

    Data.gov (United States)

    National Aeronautics and Space Administration — A method has been developed for prognostication of accrued prior damage in electronics subjected to overlapping sequential environments of thermal aging and thermal...

  14. Effects of thermal cycling and thermal aging on the hermeticity and strength of silver-copper oxide air-brazed seals

    Energy Technology Data Exchange (ETDEWEB)

    Scott Weil, K.; Coyle, Christopher A.; Hardy, John S. [Energy Science and Technology Division, Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Darsell, Jens T. [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 (United States); Xia, Gordon G. [Environmental Technology Division, Pacific Northwest National Laboratory, Richland, WA 99352 (United States)

    2005-12-01

    Thermal cycle and exposure tests were conducted on ceramic-to-metal joints prepared by a new sealing technique. Known as reactive air brazing, this joining method is currently being considered for use in sealing various high-temperature solid-state electrochemical devices, including planar solid oxide fuel cells (pSOFC). In order to simulate a typical pSOFC application, test specimens were prepared by joining ceramic anode/electrolyte bilayers to metal washers, of the same composition as the common frame materials employed in pSOFC stacks, using a filler metal composed of 4mol% CuO in silver. The brazed samples were exposure tested at 750{sup o}C for 200, 400, and 800h in both simulated fuel and air environments and thermally cycled at rapid rate (75{sup o}Cmin{sup -1}) between room temperature and 750{sup o}C for as many as 50 cycles. Subsequent joint strength testing and microstructural analysis indicated that the samples exposure tested in air displayed little degradation with respect to strength, hermeticity, or microstructure out to 800h of exposure. Those tested in fuel showed no change in rupture strength or loss in hermeticity after 800h of high-temperature exposure, but did undergo microstructural change due to the dissolution of hydrogen into the silver-based braze material. Air-brazed specimens subjected to rapid thermal cycling exhibited no loss in joint strength or hermeticity, but displayed initial signs of seal delamination along the braze-electrolyte interface after 50 cycles. (author)

  15. FY 1996 solid waste integrated life-cycle forecast characteristics summary. Volumes 1 and 2

    Energy Technology Data Exchange (ETDEWEB)

    Templeton, K.J.

    1996-05-23

    For the past six years, a waste volume forecast has been collected annually from onsite and offsite generators that currently ship or are planning to ship solid waste to the Westinghouse Hanford Company`s Central Waste Complex (CWC). This document provides a description of the physical waste forms, hazardous waste constituents, and radionuclides of the waste expected to be shipped to the CWC from 1996 through the remaining life cycle of the Hanford Site (assumed to extend to 2070). In previous years, forecast data has been reported for a 30-year time period; however, the life-cycle approach was adopted this year to maintain consistency with FY 1996 Multi-Year Program Plans. This document is a companion report to two previous reports: the more detailed report on waste volumes, WHC-EP-0900, FY1996 Solid Waste Integrated Life-Cycle Forecast Volume Summary and the report on expected containers, WHC-EP-0903, FY1996 Solid Waste Integrated Life-Cycle Forecast Container Summary. All three documents are based on data gathered during the FY 1995 data call and verified as of January, 1996. These documents are intended to be used in conjunction with other solid waste planning documents as references for short and long-term planning of the WHC Solid Waste Disposal Division`s treatment, storage, and disposal activities over the next several decades. This document focuses on two main characteristics: the physical waste forms and hazardous waste constituents of low-level mixed waste (LLMW) and transuranic waste (both non-mixed and mixed) (TRU(M)). The major generators for each waste category and waste characteristic are also discussed. The characteristics of low-level waste (LLW) are described in Appendix A. In addition, information on radionuclides present in the waste is provided in Appendix B. The FY 1996 forecast data indicate that about 100,900 cubic meters of LLMW and TRU(M) waste is expected to be received at the CWC over the remaining life cycle of the site. Based on

  16. Plasma Perfluoroalkyl and Polyfluoroalkyl Substances Concentration and Menstrual Cycle Characteristics in Preconception Women.

    Science.gov (United States)

    Zhou, Wei; Zhang, Lulu; Tong, Chuanliang; Fang, Fang; Zhao, Shasha; Tian, Ying; Tao, Yexuan; Zhang, Jun

    2017-06-22

    Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are persistent synthetic chemicals that are widely used in industrial applications and often detectable in humans. In rats, PFASs can interfere with the estrous cycle. In humans, menstruation has been viewed as a proxy of female fecundity, and periodic menstruation plays a critical role in endometrial sloughing in the absence of pregnancy and in preparing for embryo implantation. We investigated the association between PFAS exposure and menstrual cycle characteristics in women who plan to become pregnant. Plasma level of 10 PFASs was measured in 950 women who were attempting to become pregnant and recruited in two preconception care clinics in Shanghai, China, from August 2013 to April 2015. Information on menstrual cycle characteristics was collected by questionnaires. Associations between PFAS levels and menstrual cycle regularity, length, and bleeding volume were examined using multiple logistic regression models. Pre-pregnant women with higher levels of log-transformed perfluorooctanate (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoic acid (PFNA), and perfluorohexanesulfonate (PFHxS) had increased odds of self-reported history of irregular menstrual cycle [PFOA-adjusted odds ratio (OR)=1.52 (95% CI: 1.08, 2.15); PFOS OR=1.29 (95% CI: 0.98, 1.70); PFNA OR=1.50 (95% CI: 1.03, 2.07); PFHxS OR=1.80 (95% CI: 1.17, 2.77)] and long menstrual cycle [PFOA OR=1.50 (95% CI: 1.06, 2.10); PFOS OR=1.34 (95% CI: 1.02, 1.75); PFNA OR=1.49 (95% CI: 1.05, 2.11); PFHxS OR=1.73 (95% CI: 1.13, 2.65)]. Log-transformed PFOA, PFOS, PFNA. and PFHxS levels were negatively associated with self-reported history of menorrhagia [PFOA OR=0.37 (95% CI: 0.21, 0.65); PFOS OR=0.57 (95% CI: 0.37, 0.90); PFNA OR=0.47 (95% CI: 0.26, 0.86); PFHxS OR=0.14 (95% CI: 0.06, 0.36)]. Certain PFASs are associated with abnormal menstruation in humans. https://doi.org/10.1289/EHP1203.

  17. Effect of Regenerative Organic Rankine Cycle (RORC on the Performance of Solar Thermal Power in Yogyakarta, Indonesia

    Directory of Open Access Journals (Sweden)

    Ghalya Pikra

    2013-07-01

    Full Text Available This paper presents effect of Regenerative Organic Rankine Cycle (RORC on the performance of solar thermal power in Yogyakarta, Indonesia. Solar thermal power is a plant that uses solar energy as heat source. Indonesia has high humidity level, so that parabolic trough is the most suitable type of solar thermal power technology to be developed, where the design is made with small focal distance. Organic Rankine Cycle (ORC is a Rankine cycle that use organic fluid as working fluid to utilize low temperature heat sources. RORC is used to increase ORC performance. The analysis was done by comparing ORC system with and without regenerator addition. Refrigerant that be used in the analysis is R123. Preliminary data was taken from the solar collector system that has been installed in Yogyakarta. The analysis shows that with 36 m total parabolic length, the resulting solar collector capacity is 63 kW, heat input/evaporator capacity is determined 26.78 kW and turbine power is 3.11 kW for ORC, and 3.38 kW for RORC. ORC thermal efficiency is 11.28% and RORC is 12.26%. Overall electricity efficiency is 4.93% for ORC, and 5.36% for RORC. With 40°C condensing temperature and evaporation at 10 bar saturated condition, efficiency of RORC is higher than ORC. Greater evaporation temperature at the same pressure (10 bar provide greater turbine power and efficiency.

  18. Effect of thermal cycling of SiC{sub f}/SiC composites on their mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Udayakumar, A., E-mail: audayk@yahoo.com [Materials Science Division, Council of Scientific and Industrial Research – National Aerospace Laboratories, Bangalore-560 017 (India); Stalin, M.; Abhayalakshmi, M.B.; Hariharan, Ramya [Materials Science Division, Council of Scientific and Industrial Research – National Aerospace Laboratories, Bangalore-560 017 (India); Balasubramanian, M., E-mail: mbala@iitm.ac.in [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, Chennai-600 036 (India)

    2013-11-15

    SiC{sub f}/SiC composites are class of high temperature structural materials being developed for use in nuclear fusion and fission reactor systems because of their superior high temperature mechanical properties, low radiation damage and low induced radioactivity. Two types of 2D SiC{sub f}/SiC composites were made through isothermal and isobaric chemical vapor infiltration process using eight harness satin-woven ceramic-grades Nicalon™ fibers with boron nitride (BN) interface, namely: one with lower interface thickness and a second type with higher interface thickness. The BN interface was applied to the fiber prior to SiC matrix addition to modify the interfacial bond strength leading to better toughness and improved oxidation resistance. The density achieved was around 2.6 g/cc. The composite specimens were subjected to thermal cycling treatment using an in-house furnace. The mechanical properties such as tensile strength, fracture toughness and interfacial bond strength were also studied for all the composites before and after thermal cycling. It is seen from the results that both composites withstood thermal shocks and thermal cycling treatment. It was also concluded from the present work that good balance between load transfer and crack arresting was established.

  19. Outdoor thermal comfort characteristics in the hot and humid region from a gender perspective.

    Science.gov (United States)

    Tung, Chien-Hung; Chen, Chen-Peng; Tsai, Kang-Ting; Kántor, Noémi; Hwang, Ruey-Lung; Matzarakis, Andreas; Lin, Tzu-Ping

    2014-11-01

    Thermal comfort is a subjective psychological perception of people based also on physiological thermoregulation mechanisms when the human body is exposed to a combination of various environmental factors including air temperature, air humidity, wind speed, and radiation conditions. Due to the importance of gender in the issue of outdoor thermal comfort, this study compared and examined the thermal comfort-related differences between male and female subjects using previous data from Taiwanese questionnaire survey. Compared with males, the results indicated that females in Taiwan are less tolerant to hot conditions and intensely protect themselves from sun exposure. Our analytical results are inconsistent with the findings of previous physiological studies concerning thermal comfort indicating that females have superior thermal physiological tolerance than males. On the contrary, our findings can be interpreted on psychological level. Environmental behavioral learning theory was adopted in this study to elucidate this observed contradiction between the autonomic thermal physiological and psychological-behavioral aspects. Women might desire for a light skin tone through social learning processes, such as observation and education, which is subsequently reflected in their psychological perceptions (fears of heat and sun exposure) and behavioral adjustments (carrying umbrellas or searching for shade). Hence, these unique psychological and behavioral phenomena cannot be directly explained by autonomic physiological thermoregulation mechanisms. The findings of this study serve as a reference for designing spaces that accommodates gender-specific thermal comfort characteristics. Recommendations include providing additional suitable sheltered areas in open areas, such as city squares and parks, to satisfy the thermal comfort needs of females.

  20. Operating Characteristics of Expander/Compressor Combination for Carbon Dioxide Refrigeration Cycle

    Science.gov (United States)

    Fukuta, Mitsuhiro; Yanagisawa, Tadashi; Nakaya, Seiji

    An expander can improve the performance of CO2 refrigeration cycles by recovering a throttling loss. One way to utilize the recovered work is to drive an additional compressor by the expander, and it is effective to use an intercooler between a first-stage compressor and a second-stage compressor. An expander/compressor combination, in which the second-stage compressor is driven by the expander autonomously, is developed and the operating characteristics of the achine are discussed. It is operated at a balance point of mass flow rate and shaft torque between the compressor and the expander, and the balance point can be estimated using performance data of the compressor and expander. Although the expander/compressor combination improves the cycle performance, a heat rejection pressure is not maintained at an optimum pressure under off-design operating conditions. A control that keeps the heat rejection pressure optimum by a pre-expansion or a bypass is effective to obtain good performance of the CO2 refrigeration cycle with the expander/compressor combination.

  1. Characteristic points and cycles in planar kinematics with application to the human gait.

    Science.gov (United States)

    Dathe, Henning; Gezzi, Riccardo; Kubein-Meesenburg, Dietmar; Nägerl, Hans

    2015-01-01

    We present a novel method to process kinematical data typically coming from measurements of joints. This method will be illustrated through two examples. We adopt theoretical kinematics together with the principle of least action. We use motion and inverse motion for describing the whole experimental situation theoretically. By using the principle of least action, the data contain information about inherent reference points, which we call characteristic points. These points are unique for direct and inverse motion. They may be viewed as centers of the fixed and moving reference systems. The respective actions of these characteristic points are analytically calculated. The sum of these actions defines the kinematical action. This sum is by design independent of the choice of reference system. The minimality of the kinematical action can be used again to select numerically one representative cycle in empirically given, approximately periodic motions. Finally, we illustrate the theoretical approach making use of two examples worked out, hinge movement and the sagittal component of the movement of a human leg during gait. This approach enables automatic cycle choices for evaluating large databases in order to compare and to distinguish empirically given movements. The procedure can be extended to three dimensional movements.

  2. Cyclone life cycle characteristics over the Northern Hemisphere in coupled GCMs

    Energy Technology Data Exchange (ETDEWEB)

    Loeptien, Ulrike; Latif, Mojib [Leibniz-Institut fuer Meereswissenschaften, Kiel (Germany); Zolina, Olga [P. P. Shirshov Institute of Oceanology, Moscow (Russian Federation); University of Bonn, Meteorological Institute, Bonn (Germany); Gulev, Sergey [Leibniz-Institut fuer Meereswissenschaften, Kiel (Germany); P. P. Shirshov Institute of Oceanology, Moscow (Russian Federation); Soloviov, Vladimir [P. P. Shirshov Institute of Oceanology, Moscow (Russian Federation)

    2008-10-15

    Cyclone activity and life cycle are analysed in the coupled GCMs ECHAM5/OM and ECHAM4/OPYC3. First, the results for the present climate (1978-1999) are compared with ERA-40 and NCEP/NCAR reanalyses, showing a drastic improvement in the representation of cyclone activity in ECHAM5/OM compared to ECHAM4/OPYC3. The total number of cyclones, cyclone intensity, propagation velocity and deepening rates are found to be much more realistic in ECHAM5/OM relative to ECHAM4/OPYC3. Then, changes in extra tropical cyclone characteristics are compared between present day climate and future climate under the emission-scenario A1B using ECHAM5/OM. This comparison is performed using the 20-year time slices 1978-1999, 2070-2090 and 2170-2190, which were considered to be representative for the various climate conditions. The total number of cyclones does not undergo significant changes in a warmer climate. However, regional changes in cyclone numbers and frequencies are evident. One example is the Mediterranean region where the number of cyclones in summer increases almost by factor 2. Some noticeable changes are also found in cyclone life cycle characteristics (deepening rate and propagation velocity). Cyclones in the future climate scenario tend to move slower and their deepening rate becomes stronger, while cyclone intensity does not undergo significant change in a warmer climate. Generally, our results do not support the hypothesis of enhanced storminess under future climate conditions. (orig.)

  3. Thermal performance of shallow solar pond under open cycle continuous flow heating mode for heat extraction

    Energy Technology Data Exchange (ETDEWEB)

    El-Sebaii, A.A. [Department of Physics, Faculty of Science, Tanta University, Tanta 31527 (Egypt)]. E-mail: aasebaii@yahoo.com; Aboul-Enein, S. [Department of Physics, Faculty of Science, Tanta University, Tanta 31527 (Egypt); Ramadan, M.R.I. [Department of Physics, Faculty of Science, Tanta University, Tanta 31527 (Egypt); Khallaf, A.M. [Department of Physics, Faculty of Science, Tanta University, Tanta 31527 (Egypt)

    2006-05-15

    The thermal performance of a shallow solar pond (SSP) under an open cycle continuous flow heating mode for heat extraction has been investigated. A serpentine heat exchanger (HE), either welded to the absorber plate or immersed in the pond water, has been used for extracting the heat. Suitable computer programs have been developed based on analytical solutions of the energy balance equations for the various elements of the SSP in the presence of the HE. Numerical calculations have been performed to study the effect of different operational and configurational parameters on the pond performance. In order to improve the pond performance, optimization of the various dimensions of the pond with the HE has been performed. The effects of the design parameters of the HE's tube, i.e. length L{sub he}, diameter D and mass flow rate m-bar {sub f} of the fluid flowing through the HE, on the pond performance have been investigated. The outlet temperature of the HE's fluid T{sub fo} is found to increase with increase of the HE length L{sub he}, and it decreases with increase of the mass flow rate of the HE's fluid m-bar {sub f} up to typical values for these parameters. Typical values for L{sub he} and m-bar {sub f} are found to be 4m and 0.004kg/s beyond which the change in T{sub fo} becomes insignificant. Experiments have been performed for the pond under different operational conditions with a HE welded to the absorber plate. To validate the proposed mathematical models, comparisons between experimental and theoretical results have been performed. Good agreement has been achieved.

  4. Direct Chromatin PCR (DC-PCR): Hypotonic Conditions Allow Differentiation of Chromatin States during Thermal Cycling

    Science.gov (United States)

    Vatolin, Sergei; Khan, Shahper N.; Reu, Frederic J.

    2012-01-01

    Current methods to study chromatin configuration are not well suited for high throughput drug screening since they require large cell numbers and multiple experimental steps that include centrifugation for isolation of nuclei or DNA. Here we show that site specific chromatin analysis can be achieved in one step by simply performing direct chromatin PCR (DC-PCR) on cells. The basic underlying observation was that standard hypotonic PCR buffers prevent global cellular chromatin solubilization during thermal cycling while more loosely organized chromatin can be amplified. Despite repeated heating to >90°C, 41 of 61 tested 5′ sequences of silenced genes (CDKN2A, PU.1, IRF4, FOSB, CD34) were not amplifiable while 47 could be amplified from expressing cells. Two gene regions (IRF4, FOSB) even required pre-heating of cells in isotonic media to allow this differentiation; otherwise none of 19 assayed sequences yielded PCR products. Cells with baseline expression or epigenetic reactivation gave similar DC-PCR results. Silencing during differentiation of CD34 positive cord blood cells closed respective chromatin while treatment of myeloma cells with an IRF4 transcriptional inhibitor opened a site to DC-PCR that was occupied by RNA polymerase II and NFκB as determined by ChIP. Translation into real-time PCR can not be achieved with commercial real-time PCR buffers which potently open chromatin, but even with simple ethidium bromide addition to standard PCR mastermix we were able to identify hits in small molecules screens that suppressed IRF4 expression or reactivated CDKN2A in myeloma cells using densitometry or visual inspection of PCR plates under UV light. While need in drug development inspired this work, application to genome-wide analysis appears feasible using phi29 for selective amplification of open cellular chromatin followed by library construction from supernatants since such supernatants yielded similar results as gene specific DC-PCR. PMID:22984542

  5. The Influence of Thermal Cycles on the Microstructure of Grade 92 Steel

    Science.gov (United States)

    Xu, X.; West, G. D.; Siefert, J. A.; Parker, J. D.; Thomson, R. C.

    2017-11-01

    The microstructure in the heat-affected zone (HAZ) of welds made from the 9 wt pct chromium martensitic Grade 92 steel is complex and has not yet been completely understood. There is a lack of systematic microstructural investigations to define the different regions of the microstructure across the HAZ of Grade 92 steel welds as a function of the welding process. In this study, the microstructure in the HAZ of an as-fabricated single-pass bead-on-plate weld on a parent metal of Grade 92 steel was systematically investigated by using an extensive range of electron and ion-microscopy-based techniques. A dilatometer was used to apply controlled thermal cycles to simulate the microstructures in the different regions of the HAZ. A wide range of microstructural properties in the simulated materials were then characterized and compared with the experimental observations from the weld HAZ. It was found that the microstructure in the HAZ of a single-pass Grade 92 steel weld can be categorized as a function of a decreasing peak temperature reached as (1) the completely transformed (CT) region, in which the original matrix is completely reaustenitized with complete dissolution of the pre-existing secondary precipitate particles; (2) the partially transformed (PT) region, where the original matrix is partially reaustenitized along with a partial dissolution of the secondary precipitate particles from the original matrix; and (3) the overtempered (OT) region, where the pre-existing precipitate particles coarsen. The PT region is considered to be the susceptible area for damage in the commonly reported HAZ failures in weldments constructed from these types of steels.

  6. Effects of Silver Microparticles and Nanoparticles on Thermal and Electrical Characteristics of Electrically Conductive Adhesives

    Science.gov (United States)

    Zulkarnain, M.; Fadzil, M. A.; Mariatti, M.; Azid, I. A.

    2017-11-01

    The effects of different volume fractions of silver (Ag) particles of different size (microsize, 2 μm to 3.5 μm diameter; nanosize, 80 nm diameter) on the thermal and electrical characteristics of epoxy-Ag electrically conductive adhesive (ECA) have been evaluated, as well as hybrid ECAs with both particle sizes at different ratios. Improved thermal and electrical conductivity resulted from the interaction between the particles, as evaluated by analysis of sample morphology. The interaction was altered to improve the conductivity. For both particle sizes, the electrical resistivity showed a transition from insulation to conduction at 6 vol.% Ag. In the hybrid system, the thermal conductivity decreased with increasing microparticle filler ratio. The electrical conductivity of the hybrid composite increased at 50:50 weight ratio.

  7. Determination of thermal characteristics of standard and improved hollow concrete blocks using different measurement techniques

    DEFF Research Database (Denmark)

    Caruana, C.; Yousif, C.; Bacher, Peder

    2017-01-01

    project ThermHCB, with the aim of improving the U-value of such blocks without changing their compressive strength, physical dimensions or manufacturing process. Measurement techniques were applied to obtain comparative values of the thermal transmittance for standard and improved HCBs, using different EN...... and draft standards. Compressive testing was carried out concurrently in order to ensure that the minimum benchmark compressive strength was reached. The comparison between these results provides information on the reliability of the methodologies used to determine the thermal properties of building......The lighter weight, improved thermal properties and better acoustic insulation of hollow-core concrete blocks are few of the characteristics that one encounters when comparing them to traditional Maltese globigerina limestone solid blocks. As a result, hollow concrete blocks have recently been...

  8. METHOD FOR DETERMINATION OF THE CHARACTERISTIC CURVE OF THE THERMAL INERTIA OF AIRCRAFT GAS TEMPERATURE SENSORS

    Directory of Open Access Journals (Sweden)

    A. F. Sabitov

    2017-01-01

    Full Text Available The effectiveness of correction of the dynamic characteristics of gas temperature sensors in automatic control systems for the operation of aircraft gas turbine engines depends on the accuracy of the time constants of the sensors used from heat exchange conditions. The aim of this work was to develop a new method for determining the characteristic curves of the thermal inertia of gas temperature sensors.The new technique does not require finding the time constants of gas temperature sensors on the experimental transient characteristics. Characteristic curves for each time constant are defined as hyperbolic dependencies on the heat transfer coefficient of the gas temperature sensors sensing element with the gas flow. Parameters of hyperbolic dependencies are proposed to be established using two-dimensional regression analysis. For this purpose, special software has been developed in the Mathcad 14 and Mathcad 15. The software allows inputting the original data from the transient characteristics to the corresponding vectors or from tables in Excel format. It is shown that the transient characteristics in three-dimensional coordinates«time – heat transfer coefficient – the value of the transition characteristic» form a surface whose parameters are parameters of the desired hyperbolic dependencies.For a specific application of the technique, the regression functions for the dynamic characteristics of gas temperature sensors corresponding to the first and second orders are given. Analysis of the characteristic dependencies suggests that the proposed method more accurately establishes the dependence of the dynamic characteristics of aircraft gas temperature sensors on heat exchange conditions.It is shown that the algorithm of two-dimensional regression analysis realizes finding more accurate values of the parameters of the characteristic dependencies. The found parameters of the characteristic dependencies in a best way reach the surface of the

  9. Detailed analysis of the effect of the turbine and compressor isentropic efficiency on the thermal and exergy efficiency of a Brayton cycle

    Directory of Open Access Journals (Sweden)

    Živić Marija

    2014-01-01

    Full Text Available Energy and exergy analysis of a Brayton cycle with an ideal gas is given. The irreversibility of the adiabatic processes in turbine and compressor is taken into account through their isentropic efficiencies. The net work per cycle, the thermal efficiency and the two exergy efficiencies are expressed as functions of the four dimensionless variables: the isentropic efficiencies of turbine and compressor, the pressure ratio, and the temperature ratio. It is shown that the maximal values of the net work per cycle, the thermal and the exergy efficiency are achieved when the isentropic efficiencies and temperature ratio are as high as possible, while the different values of pressure ratio that maximize the net work per cycle, the thermal and the exergy efficiencies exist. These pressure ratios increase with the increase of the temperature ratio and the isentropic efficiency of compressor and turbine. The increase of the turbine isentropic efficiency has a greater impact on the increase of the net work per cycle and the thermal efficiency of a Brayton cycle than the same increase of compressor isentropic efficiency. Finally, two goal functions are proposed for thermodynamic optimization of a Brayton cycle for given values of the temperature ratio and the compressor and turbine isentropic efficiencies. The first maximizes the sum of the net work per cycle and thermal efficiency while the second the net work per cycle and exergy efficiency. In both cases the optimal pressure ratio is closer to the pressure ratio that maximizes the net work per cycle.

  10. Performance analysis of a Kalina cycle for a central receiver solar thermal power plant with direct steam generation

    DEFF Research Database (Denmark)

    Modi, Anish; Haglind, Fredrik

    2014-01-01

    without corroding the equipment by using suitable additives with the mixture. The purpose of the study reported here was to investigate if there is any benefit of using a Kalina cycle for a direct steam generation, central receiver solar thermal power plant with high live steam temperature (450 C...... direct steam generation with water/steam as both the heat transfer fluid in the solar receivers and the cycle working fluid. This enables operating the plant with higher turbine inlet temperatures. Available literature suggests that it is feasible to use ammonia-water mixtures at high temperatures......Solar thermal power plants have attracted increasing interest in the past few years - with respect to both the design of the various plant components, and extending the operation hours by employing different types of storage systems. One approach to improve the overall plant efficiency is to use...

  11. Investigation on the mechanical and thermal characteristics of potential buffer materials

    Energy Technology Data Exchange (ETDEWEB)

    Han, Dae Suk; Kim, Kyeong Su [Korea Institute of Geology, Mining and Materials, Taejon (Korea)

    1998-12-01

    The bentonite from the Taekwang Chemical Corporation was tested for its specific gravity, grain-size distribution, Atterberg limits, linear shrinkage, mineralogy, chemistry, compaction characteristics, unconfined compression strength, Young's modulus, poisson's ratio, shear strength, consolidation characteristics, and thermal conductivity. The Jawoldo and was tested for its specific gravity, grain-size distribution, chemistry, and mineralogy. The mixtures of bentonite and sand also were subjected to a laboratory testing program including Atteberg limits, linear shrinkage, unconfined compressive strength, Young's modulus, poisson's ratio, shear strength, and thermal conductivity. All the test procedures and results are described in the paper. (author). 13 refs., 60 figs., 19 tabs.

  12. Large hydrocarbon fuel pool fires: Physical characteristics and thermal emission variations with height

    Energy Technology Data Exchange (ETDEWEB)

    Raj, Phani K. [Technology and Management Systems Inc., 102 Drake Road, Burlington, MA 01803 (United States)]. E-mail: tmsinc1981@verizon.net

    2007-02-09

    In a recent paper [P.K. Raj, Large LNG fire thermal radiation-modeling issues and hazard criteria revisited, Process Safety Progr., 24 (3) (2005)] it was shown that large, turbulent fires on hydrocarbon liquid pools display several characteristics including, pulsating burning, production of smoke, and reduced thermal radiation, with increasing size. In this paper, a semi-empirical mathematical model is proposed which considers several of these important fire characteristics. Also included in this paper are the experimental results for the variation of the fire radiance from bottom to top of the fire (and their statistical distribution) from the largest land spill LNG pool fire test conducted to date. The purpose of the model described in this paper is to predict the variation of thermal radiation output along the fire plume and to estimate the overall thermal emission from the fire as a function its size taking into consideration the smoke effects. The model utilizes experimentally measured data for different parameters and uses correlations developed from laboratory and field tests with different fuels. The fire dynamics and combustion of the fuel are modeled using known entrainment and combustion efficiency parameter values. The mean emissive power data from field tests are compared with model predictions. Model results for the average emissive powers of large, hypothetical LNG fires are indicated.

  13. Recent developments in thermally-driven seawater desalination: Energy efficiency improvement by hybridization of the MED and AD cycles

    KAUST Repository

    Ng, Kim Choon

    2015-01-01

    The energy, water and environment nexus is a crucial factor when considering the future development of desalination plants or industry in the water-stressed economies. New generation of desalination processes or plants has to meet the stringent environment discharge requirements and yet the industry remains highly energy efficient and sustainable when producing good potable water. Water sources, either brackish or seawater, have become more contaminated as feed while the demand for desalination capacities increase around the world. One immediate solution for energy efficiency improvement comes from the hybridization of the proven desalination processes to the newer processes of desalination: For example, the integration of the available thermally-driven to adsorption desalination (AD) cycles where significant thermodynamic synergy can be attained when cycles are combined. For these hybrid cycles, a quantum improvement in energy efficiency as well as in increase in water production can be expected. The advent of MED with AD cycles, or simply called the MEDAD cycles, is one such example where seawater desalination can be pursued and operated in cogeneration with the electricity production plants: The hybrid desalination cycles utilize only the low exergy bled-steam at low temperatures, complemented with waste exhaust or renewable solar thermal heat at temperatures between 60 and 80. °C. In this paper, the authors have reported their pioneered research on aspects of AD and related hybrid MEDAD cycles, both at theoretical models and experimental pilots. Using the cogeneration of electricity and desalination concept, the authors examined the cost apportionment of fuel cost by the quality or exergy of working steam for such cogeneration configurations.

  14. Analysis of in-cavity thermal and pressure characteristics in aluminum alloy die casting

    Energy Technology Data Exchange (ETDEWEB)

    Venkatasamy, Vasanth Kumar [The Ohio State Univ., Columbus, OH (United States)

    1996-01-01

    The lack of effective control of the die casting process is the primary reason for the occurrence of defective die cast products. A reliable process control system must be capable of measuring the process variables, comparing them to the standard or ideal values and making suitable alterations in the process to eliminate any deviation from the ideal. This study attempted to facilitate the development of such a process control system. A two pronged approach was used to achieve this objective. The experimental approach addressed some of the problems in the measurement of process variables. The analytical approach addressed some of the problems in the design of the process and subsequent identification of the ideal process variable values. The experimental approach concentrated on the measurement of in-cavity pressure and thermal characteristics of the die casting process. Kistler direct pressure sensors were evaluated and utilized for cavity pressure measurement during the die casting campaign. Thermal probes using staggered thermocouples were developed and utilized for the simultaneous measurement of die surface temperatures and heat flow rate through the die. The measured thermal and pressure characteristics were related to the injection characteristics measured using the shot control equipment of the Buhler H-250SC die casting machine used in the campaign. The analytical approach concentrated on the verification of the predictions of a computer numerical solidification analysis by comparison with the experimental data obtained as an output of the die casting campaign. Particular attention was paid to the predictions of thermal characteristics like freezing time and die surface temperature. A sensitivity analysis was also performed to determine the effect of changes in individual variables on the predictions of BINORM.

  15. A Data Analysis Technique to Estimate the Thermal Characteristics of a House

    Directory of Open Access Journals (Sweden)

    Seyed Amin Tabatabaei

    2017-09-01

    Full Text Available Almost one third of the energy is used in the residential sector, and space heating is the largest part of energy consumption in our houses. Knowledge about the thermal characteristics of a house can increase the awareness of homeowners about the options to save energy, for example by showing that there is room for improvement of the insulation level. However, calculating the exact value of these characteristics is not possible without precise thermal experiments. In this paper, we propose a method to automatically estimate two of the most important thermal characteristics of a house, i.e., the loss rate and the heat capacity, based on collected data about the temperature and gas usage. The method is evaluated with a data set that has been collected in a real-life case study. Although a ground truth is lacking, the analyses show that there is evidence that this method could provide a feasible way to estimate those values from the thermostat data. More detailed data about the houses in which the data was collected is required to draw stronger conclusions. We conclude that the proposed method is a promising way to add energy saving advice to smart thermostats.

  16. Effect of weld thermal cycle on the electrochemical corrosion of Q315NS steel in acidic solution

    Science.gov (United States)

    Zhang, Suqiang; Shu, Fengyuan; Zhao, Hongyun; Wang, Guodong; Wang, Shuai; Wang, Wenjian

    2017-04-01

    The effect of welding thermal process on the electrochemical corrosion of Q315NS in H2SO4 and HCl solution were investigated. Different weld thermal cycles with different peak temperatures were used in a Gleeble thermal-force simulation testing machine to simulate weld HAZ, and electrochemical measurements were carried out. The results demonstrate that a microstructure of granular bainite was generated in CGHAZ while others consisted of ferrite and pearlite. The electrochemical corrosion of different HAZ was different in H2SO4 and HCl, due to different microstructure. The BM and HAZs in 50 wt. % H2SO4 solution has a certain passivation behavior, while there was no passivation behavior in 3.5 wt. % HCl solution. The corrosion resistances in HAZs are inferior to that in BM. In addition, the corrosion resistance in the CGHAZ is the weakest.

  17. Phase transformations in thermally cycled Cu/ZrW2O8 composites investigated by synchrotron x-ray diffraction

    Science.gov (United States)

    Yilmaz, S.

    2002-01-01

    A Cu/ZrW2O8 metal matrix composite was thermally cycled between 298 and 591 K while being subjected to x-ray diffraction in transmission using high-intensity synchrotron radiation. The reversible allotropic phase transformations of ZrW2O8 between its two low-pressure phases and its high-pressure phase were observed within the composite bulk as a function of temperature. This observation gives experimental proof of the existence of the reversible pressure-induced phase transformation, which had been inferred indirectly from dilatometry in a previous investigation and assigned to the large thermal mismatch stresses in the composite. The volume fraction of each ZrW2O8 compound was determined from the measured diffracted intensity, and the thermal expansion behaviour of the composite was then calculated. Good agreement was found with the experimental dilatometric curve reported in a recent investigation.

  18. Insulin binding characteristics in canine muscle tissue: effects of the estrous cycle phases

    Directory of Open Access Journals (Sweden)

    Álan G. Pöppl

    Full Text Available Abstract: Hormonal fluctuations during the different estrous cycle are a well-recognized cause of insulin resistance in bitches, and little is known about insulin receptor binding or post-binding defects associated with insulin resistance in dogs. To evaluate insulin binding characteristics in muscle tissue of bitches during the estrous cycle, 17 owned bitches were used in the study (six in anestrus, five in estrus, and six in diestrus. An intravenous glucose tolerance test (IVGTT was performed in all patients by means of injection of 1mL/kg of a glucose 50% solution (500mg/kg, with blood sample collection for glucose determination at 0, 3, 5, 7, 15, 30, 45 and 60 minutes after glucose infusion. Muscle samples, taken after spaying surgery, were immediately frozen in liquid nitrogen and then stored at -80 ºC until the membranes were prepared by sequential centrifugation after being homogenized. For binding studies, membranes were incubated in the presence of 20,000cpm of human 125I-insulin and in increasing concentrations of unlabeled human regular insulin for cold saturation. The IVGTT showed no differences among bitches during the estrous cycle regarding baseline glycemia or glycemic response after glucose infusion. Two insulin binding sites - high-affinity and low-affinity ones - were detected by Scatchard analysis, and significant statistical differences were observed in the dissociation constant (Kd1 and maximum binding capacity (Bmax1 of the high-affinity binding sites. The Kd1 for the anestrus group (6.54±2.77nM/mg of protein was smaller (P<0.001 than for the estrus (28.54±6.94nM/mg of protein and diestrus (15.56±3.88nM/mg of protein groups. Bmax1 in the estrus (0.83±0.42nM/mg of protein and diestrus (1.24±0.24nM/mg of protein groups were also higher (P<0.001 than the values observed in anestrus (0.35±0.06nM/mg of protein. These results indicate modulation of insulin binding characteristics during different phases of the estrous

  19. Adsorption Characteristics of Water and Silica Gel System for Desalination Cycle

    KAUST Repository

    Cevallos, Oscar R.

    2012-07-01

    An adsorbent suitable for adsorption desalination cycles is essentially characterized by a hydrophilic and porous structure with high surface area where water molecules are adsorbed via hydrogen bonding mechanism. Silica gel type A++ possesses the highest surface area and exhibits the highest equilibrium uptake from all the silica gels available in the market, therefore being suitable for water desalination cycles; where adsorbent’s adsorption characteristics and water vapor uptake capacity are key parameters in the compactness of the system; translated as feasibility of water desalination through adsorption technologies. The adsorption characteristics of water vapor onto silica gel type A++ over a temperature range of 30 oC to 60 oC are investigated in this research. This is done using water vapor adsorption analyzer utilizing a constant volume and variable pressure method, namely the Hydrosorb-1000 instrument by Quantachrome. The experimental uptake data is studied using numerous isotherm models, i. e. the Langmuir, Tóth, generalized Dubinin-Astakhov (D-A), Dubinin-Astakhov based on pore size distribution (PSD) and Dubinin-Serpinski (D-Se) isotherm for the whole pressure range, and for a pressure range below 10 kPa, proper for desalination cycles; isotherms type V of the International Union of Pure and Applied Chemistry (IUPAC) classification were exhibited. It is observed that the D-A based on PSD and the D-Se isotherm models describe the best fitting of the experimental uptake data for desalination cycles within a regression error of 2% and 6% respectively. All isotherm models, except the D-A based on PSD, have failed to describe the obtained experimental uptake data; an empirical isotherm model is proposed by observing the behavior of Tóth and D-A isotherm models. The new empirical model describes the water adsorption onto silica gel type A++ within a regression error of 3%. This will aid to describe the advantages of silica gel type A++ for the design of

  20. Computer assisted semen analysis for quantification of motion characteristics of bull sperm during cryopreservation cycle

    Directory of Open Access Journals (Sweden)

    M. N. Sundararaman

    Full Text Available Aim: The study was undertaken to quantify and to analyze the changes in the motion characteristics of bull spermatozoa during various stages of cryopreservation cycle. Materials and Methods: Using computer assisted semen analysis (CASA technique, 26 ejaculates, collected from two Jersey bulls were analyzed for motility, head behaviour and swimming pattern of spermatozoa on dilution, pre-freeze and post-thaw stages of cryopreservation. French straw technique was employed for deep-freezing of semen using liquid nitrogen. Results: Equilibration of diluted semen at 5 C has significantly (P< 0.01 reduced sperm motility, progressive motility, path velocity, and progressive velocity. Beat cross frequency was also affected significantly (P<0.05 by equilibration. Freezing and thawing processes drastically affected all the motility, velocity and head behaviour characteristics (P< 0.01. Conclusion: CASA facilitate objective evaluation sperm motion characteristics. Adoption of CASA technique has the potential for improvements in evaluation of semen thereby the quality of frozen semen for fertility can be enhanced. [Vet World 2012; 5(12.000: 723-726

  1. University of Minnesota aquifer thermal energy storage (ATES) project report on the second long-term cycle

    Energy Technology Data Exchange (ETDEWEB)

    Hoyer, M.C.; Hallgren, J.P.; Lauer, J.L.; Walton, M.; Eisenreich, S.J.; Howe, J.T.; Splettstoesser, J.F. (Minnesota Geological Survey, St. Paul, MN (United States))

    1991-12-01

    The technical feasibility of high-temperature (>100{degrees}C (>212{degrees}F)) aquifer thermal energy storage (ATES) in a deep, confined aquifer was tested in a series of experimental cycles at the University of Minnesota's St. Paul field test facility (FTF). This report describes the second long-term cycle (LT2), which was conducted from October 1986 through April 1987. Heat recovery; operational experience; and thermal, chemical, hydrologic, and geologic effects are reported. Approximately 61% of the 9.21 GWh of energy added to the 9.38 {times} 10{sup 4} m{sup 3} of ground water stored during LT2 was recovered. Temperatures of the water stored and recovered averaged 118{degrees}C (244{degrees}F) and 85{degrees}C (185{degrees}F), respectively. Results agreed with previous cycles conducted at the FTF. System operation during LT2 was nearly as planned. Operational experience from previous cycles at the FTF was extremely helpful. Ion-exchange softening of the heated and stored aquifer water prevented scaling in the system heat exchangers and the storage well, and changed the major-ion chemistry of the stored water. Sodium bicarbonate replaced magnesium and calcium bicarbonate as primary ions in the softened water. Water recovered form storage was approximately at equilibrium with respect to dissolved ions. Silica, calcium, and magnesium were significantly higher in recovered water than in injected water. Sodium was significantly lower in water recovered than in water stored.

  2. University of Minnesota aquifer thermal energy storage (ATES) project report on the second long-term cycle

    Energy Technology Data Exchange (ETDEWEB)

    Hoyer, M.C.; Hallgren, J.P.; Lauer, J.L.; Walton, M.; Eisenreich, S.J.; Howe, J.T.; Splettstoesser, J.F. [Minnesota Geological Survey, St. Paul, MN (United States)

    1991-12-01

    The technical feasibility of high-temperature [>100{degrees}C (>212{degrees}F)] aquifer thermal energy storage (ATES) in a deep, confined aquifer was tested in a series of experimental cycles at the University of Minnesota`s St. Paul field test facility (FTF). This report describes the second long-term cycle (LT2), which was conducted from October 1986 through April 1987. Heat recovery; operational experience; and thermal, chemical, hydrologic, and geologic effects are reported. Approximately 61% of the 9.21 GWh of energy added to the 9.38 {times} 10{sup 4} m{sup 3} of ground water stored during LT2 was recovered. Temperatures of the water stored and recovered averaged 118{degrees}C (244{degrees}F) and 85{degrees}C (185{degrees}F), respectively. Results agreed with previous cycles conducted at the FTF. System operation during LT2 was nearly as planned. Operational experience from previous cycles at the FTF was extremely helpful. Ion-exchange softening of the heated and stored aquifer water prevented scaling in the system heat exchangers and the storage well, and changed the major-ion chemistry of the stored water. Sodium bicarbonate replaced magnesium and calcium bicarbonate as primary ions in the softened water. Water recovered form storage was approximately at equilibrium with respect to dissolved ions. Silica, calcium, and magnesium were significantly higher in recovered water than in injected water. Sodium was significantly lower in water recovered than in water stored.

  3. Unsaturated polyester/expanded polystyrene composite : thermal characteristics and flame retardancy effects

    Science.gov (United States)

    Mohamed, R.; Syed Mustafa, S. A.; Norizan, Mohd N.; Amerudin, L. S.

    2017-07-01

    Panels for energy efficient buildings has to meet certain requirements such as low thermal conductivity and inherent flame retardancy characteristics, before being eligible for buildings and construction applications. Expanded Polystyrene (EPS) as waste material had been incorporated as filler in Unsaturated Polyester Resin (UPR) composites. The composite are fabricated as flat panel window or glazing to replace glass. In this study, different EPS content incorporated was found to affect flammability and thermal characteristics. Core additives such as Flame Retardant (FR) and Antioxidant (AO) were added to the composite for imparting flame retardancy and prevent aging of the composite. The result obtained via the comparison of the various composite systems studied had revealed that organic and metal oxide flame retardant (FR) additives imparts higher flame retardancy levels than others, but each type of additives had interacted with the polymeric matrixes differently. The thermal conductivity, k value, as measured from a handheld thermal probe had showed a minimum of ~0.124 W/m.K for the 1%wt zinc oxide sample, while the highest k value of ~0.280 W/m.K was exhibited by the 2%wt tin oxide sample. The first 1%wt of either metal oxide FR initially decreases both the thermal conductivity, k value; and volumetric specific heat, Cp,v of the samples. At 2%wt, increases in k value were obtained. The flammability was reduced with the use of organic Phosphate Ester FR, which had reduced the flame speed to about 37.1% of the original flame speed. With the equivalent mixture of all three organic FR system, the flammability reduced less than 30%, while the metal oxide FR additive doesn't reduces the flammability.

  4. Comparative evaluation of thermal oxidative decomposition for oil-plant residues via thermogravimetric analysis: Thermal conversion characteristics, kinetics, and thermodynamics.

    Science.gov (United States)

    Chen, Jianbiao; Wang, Yanhong; Lang, Xuemei; Ren, Xiu'e; Fan, Shuanshi

    2017-11-01

    Thermal oxidative decomposition characteristics, kinetics, and thermodynamics of rape straw (RS), rapeseed meal (RM), camellia seed shell (CS), and camellia seed meal (CM) were evaluated via thermogravimetric analysis (TGA). TG-DTG-DSC curves demonstrated that the combustion of oil-plant residues proceeded in three stages, including dehydration, release and combustion of organic volatiles, and chars oxidation. As revealed by combustion characteristic parameters, the ignition, burnout, and comprehensive combustion performance of residues were quite distinct from each other, and were improved by increasing heating rate. The kinetic parameters were determined by Coats-Redfern approach. The results showed that the most possible combustion mechanisms were order reaction models. The existence of kinetic compensation effect was clearly observed. The thermodynamic parameters (ΔH, ΔG, ΔS) at peak temperatures were calculated through the activated complex theory. With the combustion proceeding, the variation trends of ΔH, ΔG, and ΔS for RS (RM) similar to those for CS (CM). Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Investigation of individual and group variability in estrous cycle characteristics in female Asian elephants (Elephas maximus) at the Oregon Zoo.

    Science.gov (United States)

    Glaeser, S S; Hunt, K E; Martin, M S; Finnegan, M; Brown, J L

    2012-07-15

    Evaluating ovarian cycle activity through longitudinal progestagen monitoring is important for optimizing breeding management of captive elephants and understanding impact of life events (births, deaths, and transfers) on reproductive function. This study summarized serum progestagen profiles for eight Asian mainland elephants (Elephas maximus indicus) and one Bornean elephant (E. maximus borneensis) at the Oregon Zoo over a 20-yr interval, and represents the longest longitudinal dataset evaluated to date. Estrous cycle characteristics were more varied than previously reported for this species, with an overall duration of 12 to 19 wk, luteal phase duration of 4 to 15 wk, and follicular phase duration of 2 to 12 wk. In general, there was more cycle variability across than within individual elephants. Compared with other elephants in the group, the Borneo female exhibited consistently longer cycle lengths, higher progestagen concentrations, and greater cycle variability; however, it is not known if this represents a subspecies or an individual difference. Cycle durations did not appear to change over time or with age, and the first pubertal cycle was similar to subsequent cycles. Variability in duration of the follicular phase was greater than that of the luteal phase. In addition, there was a significant negative relationship between luteal and follicular phase durations, suggesting a possible regulatory role of the follicular phase in maintaining a relatively consistent cycle duration within individuals. Overall, we found these elephants to be highly resilient in that major life events (births, deaths, and changes in herd structure) had minimal effect on cycle dynamics over time. In conclusion, the higher range in cycle phase characteristics is likely because of the larger number of elephants studied and longer duration of longitudinal monitoring, and may be more representative of the captive population as a whole. Furthermore, identification of significant

  6. High-cycle fatigue characteristics of weldable steel for light-water reactors

    Energy Technology Data Exchange (ETDEWEB)

    Klesnil, M.; Polak, J.; Obrtlik, K. (Ceskoslovenska Akademie Ved, Brno. Ustav Fyzikalni Metalurgie); Troshchenko, V.T.; Mishchenko, Yu.I.; Khamaza, L.A. (AN Ukrainskoj SSR, Kiev. Inst. Problem Prochnosti)

    1982-11-01

    Czechoslovak and Soviet 15Kh2NMFA steel was used for running fatigue tests at temperatures of 20, 350 and 400 degC in the high-cycle range with various loading regimes. The results show that at the given temperatures in this type of steel a cyclic softening occurs. The fatigue characteristics were measured with great dispersion of results, but within this dispersion they are almost identical for various steels at the same temperature. Increased temperature results in the decrease in the amplitude of cyclic deformation stress and in the increase in the amplitude of plastic deformation. The diversity in the values of cyclic plasticity and stress response measured in the given mode may be explained by the lower level of softening and the non-homogeneous cyclic plastic deformation of material under the given constant conditions.

  7. Unsteady flow characteristic analysis of turbine based combined cycle (TBCC inlet mode transition

    Directory of Open Access Journals (Sweden)

    Jun Liu

    2015-09-01

    Full Text Available A turbine based combined cycle (TBCC propulsion system uses a turbine-based engine to accelerate the vehicle from takeoff to the mode transition flight condition, at which point, the propulsion system performs a “mode transition” from the turbine to ramjet engine. Smooth inlet mode transition is accomplished when flow is diverted from one flowpath to the other, without experiencing unstart or buzz. The smooth inlet mode transition is a complex unsteady process and it is one of the enabling technologies for combined cycle engine to become a functional reality. In order to unveil the unsteady process of inlet mode transition, the research of over/under TBCC inlet mode transition was conducted through a numerical simulation. It shows that during the mode transition the terminal shock oscillates in the inlet. During the process of inlet mode transition mass flow rate and Mach number of turbojet flowpath reduce with oscillation. While in ramjet flowpath the flow field is non-uniform at the beginning of inlet mode transition. The speed of mode transition and the operation states of the turbojet and ramjet engines will affect the motion of terminal shock. The result obtained in present paper can help us realize the unsteady flow characteristic during the mode transition and provide some suggestions for TBCC inlet mode transition based on the smooth transition of thrust.

  8. STATISTICAL STUDY OF STRONG AND EXTREME GEOMAGNETIC DISTURBANCES AND SOLAR CYCLE CHARACTERISTICS

    Energy Technology Data Exchange (ETDEWEB)

    Kilpua, E. K. J. [Department of Physics, University Helsinki (Finland); Olspert, N.; Grigorievskiy, A.; Käpylä, M. J.; Tanskanen, E. I.; Pelt, J. [ReSoLVE Centre of Excellence, Department of Computer Science, P.O. Box 15400, FI-00076 Aalto Univeristy (Finland); Miyahara, H. [Musashino Art University, 1-736 Ogawa-cho, Kodaira-shi, Tokyo 187-8505 (Japan); Kataoka, R. [National Institute of Polar Research, 10-3 Midori-cho, Tachikawa, Tokyo 190-8518 (Japan); Liu, Y. D. [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China)

    2015-06-20

    We study the relation between strong and extreme geomagnetic storms and solar cycle characteristics. The analysis uses an extensive geomagnetic index AA data set spanning over 150 yr complemented by the Kakioka magnetometer recordings. We apply Pearson correlation statistics and estimate the significance of the correlation with a bootstrapping technique. We show that the correlation between the storm occurrence and the strength of the solar cycle decreases from a clear positive correlation with increasing storm magnitude toward a negligible relationship. Hence, the quieter Sun can also launch superstorms that may lead to significant societal and economic impact. Our results show that while weaker storms occur most frequently in the declining phase, the stronger storms have the tendency to occur near solar maximum. Our analysis suggests that the most extreme solar eruptions do not have a direct connection between the solar large-scale dynamo-generated magnetic field, but are rather associated with smaller-scale dynamo and resulting turbulent magnetic fields. The phase distributions of sunspots and storms becoming increasingly in phase with increasing storm strength, on the other hand, may indicate that the extreme storms are related to the toroidal component of the solar large-scale field.

  9. Thermal Characteristics of Conversion-Type FeOF Cathode in Li-ion Batteries

    Directory of Open Access Journals (Sweden)

    Liwei Zhao

    2017-10-01

    Full Text Available Rutile FeOF was used as a conversion-type cathode material for Li-ion batteries. In the present study, 0.6Li, 1.4Li, and 2.7Li per mole lithiation reactions were carried out by changing the electrochemical discharge reaction depth. The thermal characteristics of the FeOF cathode were investigated by thermogravimetric mass spectrometric (TG-MS and differential scanning calorimeter (DSC systems. No remarkable HF release was detected, even up to 700 °C, which indicated a low toxic risk for the FeOF cathode. Changes in the thermal properties of the FeOF cathode via different conversion reaction depths in the associated electrolyte were studied by changing the cathode/electrolyte ratio in the mixture. LiFeOF was found to exothermically react with the electrolyte at about 210 °C. Similar exothermic reactions were found with charged FeOF cathodes because of the irreversible Li ions. Among the products of the conversion reaction of FeOF, Li2O was found to exothermically react with the electrolyte at about 120 °C, which induced the main thermal risk of the FeOF cathode. It suggests that the oxygen-containing conversion-type cathodes have a higher thermal risk than the oxygen-free ones, but controlling the cathode/electrolyte ratio in cells successfully reduced the thermal risk. Finally, the thermal stability of the FeOF cathode was evaluated in comparison with FeF3 and LiFePO4 cathodes.

  10. Human power output during repeated sprint cycle exercise: the influence of thermal stress

    NARCIS (Netherlands)

    Ball, D.; Burrows, C.; Sargeant, A.J.

    1999-01-01

    Thermal stress is known to impair endurance capacity during moderate prolonged exercise. However, there is relatively little available information concerning the effects of thermal stress on the performance of high-intensity short-duration exercise. The present experiment examined human power output

  11. Thermal infrared emissivity spectrum and its characteristics of crude oil slick covered seawater.

    Science.gov (United States)

    Xiong, Pan; Gu, Xing-Fai; Yu, Taol; Meng, Qing-Yan; Li, Jia-Guoi; Shi, Ji-xiang; Cheng, Yang; Wang, Liang; Liu, Wen-Song; Liu, Qi-Yuei; Zhao, Li-Min

    2014-11-01

    Detecting oil slick covered seawater surface using the thermal infrared remote sensing technology exists the advantages such as: oil spill detection with thermal infrared spectrum can be performed in the nighttime which is superior to visible spectrum, the thermal infrared spectrum is superior to detect the radiation characteristics of both the oil slick and the seawater compared to the mid-wavelength infrared spectrum and which have great potential to detect the oil slick thickness. And the emissivity is the ratio of the radiation of an object at a given temperature in normal range of the temperature (260-320 K) and the blackbody radiation under the same temperature , the emissivity of an object is unrelated to the temperature, but only is dependent with the wavelength and material properties. Using the seawater taken from Bohai Bay and crude oil taken from Gudao oil production plant of Shengli Oilfield in Dongying city of Shandong Province, an experiment was designed to study the characteristics and mechanism of thermal infrared emissivity spectrum of artificial crude oil slick covered seawater surface with its thickness. During the experiment, crude oil was continuously dropped into the seawater to generate artificial oil slick with different thicknesses. By adding each drop of crude oil, we measured the reflectivity of the oil slick in the thermal infrared spectrum with the Fourier transform infrared spectrometer (102F) and then calculated its thermal infrared emissivity. The results show that the thermal infrared emissivity of oil slick changes significantly with its thickness when oil slick is relatively thin (20-120 μm), which provides an effective means for detecting the existence of offshore thin oil slick In the spectrum ranges from 8 to 10 μm and from 13. 2 to 14 μm, there is a steady emissivity difference between the seawater and thin oil slick with thickness of 20 μm. The emissivity of oil slick changes marginally with oil slick thickness and

  12. Development of a thermal scheme for a cogeneration combined-cycle unit with an SVBR-100 reactor

    Science.gov (United States)

    Kasilov, V. F.; Dudolin, A. A.; Krasheninnikov, S. M.

    2017-02-01

    At present, the prospects for development of district heating that can increase the effectiveness of nuclear power stations (NPS), cut down their payback period, and improve protection of the environment against harmful emissions are being examined in the nuclear power industry of Russia. It is noted that the efficiency of nuclear cogeneration power stations (NCPS) is drastically affected by the expenses for heat networks and heat losses during transportation of a heat carrier through them, since NPSs are usually located far away from urban area boundaries as required for radiation safety of the population. The prospects for using cogeneration power units with small or medium power reactors at NPSs, including combined-cycle units and their performance indices, are described. The developed thermal scheme of a cogeneration combined-cycle unit (CCU) with an SBVR-100 nuclear reactor (NCCU) is presented. This NCCU should use a GE 6FA gasturbine unit (GTU) and a steam-turbine unit (STU) with a two-stage district heating plant. Saturated steam from the nuclear reactor is superheated in a heat-recovery steam generator (HRSG) to 560-580°C so that a separator-superheater can be excluded from the thermal cycle of the turbine unit. In addition, supplemental fuel firing in HRSG is examined. NCCU effectiveness indices are given as a function of the ambient air temperature. Results of calculations of the thermal cycle performance under condensing operating conditions indicate that the gross electric efficiency η el NCCU gr of = 48% and N el NCCU gr = 345 MW can be achieved. This efficiency is at maximum for NCCU with an SVBR-100 reactor. The conclusion is made that the cost of NCCU installed kW should be estimated, and the issue associated with NCCUs siting with reference to urban area boundaries must be solved.

  13. Thermal diffusion characteristics of atmosphere-particle two phase flow in dust storm

    Science.gov (United States)

    Wang, Xihua; Wang, Tijian; Tang, Jianping; Gu, Fan

    2005-02-01

    A model, coupling metrological dynamic model MM5 and dust transport model, is developed for the atmosphere-particle two phases flow of dust storm. The simulations of the dust storm events in north China with a geographic information database are performed using the model, and represent an overview of dust transport pathways and particles concentration distribution over the north China. The comparison between computations and practical observations shows that the simulations succeed in description of dust storm evolvement and particle transport behavior. Based on the computations and analysis, the characteristics of particle transport, especially well-concerning the factor of the particle thermal diffusion, are studied. A new definition of mass transfer Grd is put forward to discover the internal principle of particle thermal diffusion at various atmospheric layers. Several phenomena, such as thermal diffusion item QT Grd distribution, and relationships, Particle Grd probability function, are obtained. The investigation indicates particle thermal diffusion can be not ignored in mesoscale atmospheric-particle multiphase flow.

  14. Seasonal redistribution of immune function in migrant shorebird: annual cycle effects override adjustments to thermal regime

    NARCIS (Netherlands)

    Buehler, D.M.; Piersma, T.; Matson, K.D.; Tieleman, B.I.

    2008-01-01

    Throughout the annual cycle, demands on competing physiological systems change, and animals must allocate resources to maximize fitness. Immune function is one such system and is important for survival. Yet detailed empirical data tracking immune function over the entire annual cycle are lacking for

  15. Long-term calcination/carbonation cycling and thermal pretreatment for CO{sub 2} capture by limestone and dolomite

    Energy Technology Data Exchange (ETDEWEB)

    Zhongxiang Chen; Hoon Sub Song; Miguel Portillo; C. Jim Lim; John R. Grace; E.J. Anthony [University of British Columbia, Vancouver, BC (Canada). Department of Chemical and Biological Engineering

    2009-03-15

    Capturing carbon dioxide is vital for the future of climate-friendly combustion, gasification, and steam-re-forming processes. Dry processes utilizing simple sorbents have great potential in this regard. Long-term calcination/carbonation cycling was carried out in an atmospheric-pressure thermogravimetric reactor. Although dolomite gave better capture than limestone for a limited number of cycles, the advantage declined over many cycles. Under some circumstances, decreasing the carbonation temperature increased the rate of reaction because of the interaction between equilibrium and kinetic factors. Limestone and dolomite, after being pretreated thermally at high temperatures (1000 or 1100{sup o}C), showed a substantial increase in calcium utilization over many calcination/carbonation cycles. Lengthening the pretreatment interval resulted in greater improvement. However, attrition was significantly greater for the pretreated sorbents. Greatly extending the duration of carbonation during one cycle was found to be capable of restoring the CO{sub 2} capture ability of sorbents to their original behavior, offering a possible means of countering the long-term degradation of calcium sorbents for dry capture of carbon dioxide. 12 refs., 12 figs., 2 tabs.

  16. Effect of variable heat input on the heat transfer characteristics in an Organic Rankine Cycle system

    Directory of Open Access Journals (Sweden)

    Aboaltabooq Mahdi Hatf Kadhum

    2016-01-01

    Full Text Available This paper analyzes the heat transfer characteristics of an ORC evaporator applied on a diesel engine using measured data from experimental work such as flue gas mass flow rate and flue gas temperature. A mathematical model was developed with regard to the preheater, boiler and the superheater zones of a counter flow evaporator. Each of these zones has been subdivided into a number of cells. The hot source of the ORC cycle was modeled. The study involves the variable heat input's dependence on the ORC system's heat transfer characteristics, with especial emphasis on the evaporator. The results show that the refrigerant's heat transfer coefficient has a higher value for a 100% load from the diesel engine, and decreases with the load decrease. Also, on the exhaust gas side, the heat transfer coefficient decreases with the decrease of the load. The refrigerant's heat transfer coefficient increased normally with the evaporator's tube length in the preheater zone, and then increases rapidly in the boiler zone, followed by a decrease in the superheater zone. The exhaust gases’ heat transfer coefficient increased with the evaporator’ tube length in all zones. The results were compared with result by other authors and were found to be in agreement.

  17. The life-cycle of hailstorms: Lightning, radar reflectivity and rotation characteristics

    Science.gov (United States)

    Wapler, Kathrin

    2017-09-01

    An 8-year analysis of hailstorms is presented. A comprehensive set of six hundred hailstorms that occurred in 172 different days in various parts of Germany is used to characterise these events. The analysed observations include measurements from a lightning location system, precipitation radar, as well as information from automated cell detection algorithms based on radar reflectivity and radial winds which are combined with severe weather reports. Additionally to the storms' parameters during the time of the observed hail, the temporal evolution of the storms' characteristics is analysed in order to study the convective life-cycle and identify parameters with predictive skill. A special focus is on the lightning characteristics of the convective cells. A feature that is shown to occur in many of the analysed severe hail cases is the lightning jump, i.e., a rapid increase in the total lightning density. It occurs well before the observed hail and has thus a great potential to increase the lead time of warnings of severe hail events. Instead of fixed thresholds for the definition of a lightning jump, a lightning jump intensity parameter is introduced and tested. The analysis also reveals that half to the storms show a pulsating lightning activity. Nearly three quarters of the hail events are associated with a mesocyclone that was automatically detected in radar data. As expected, high reflectivity values were measured during the time of the observed hail.

  18. Effects of bonding bakeout thermal cycles on pre- and post irradiation microstructures, physical, and mechanical properties of copper alloys

    Energy Technology Data Exchange (ETDEWEB)

    Singh, B.N.; Eldrup, M.; Toft, P.; Edwards, D.J. [Pacific Northwest National Laboratory, Richland, WA (United States)

    1996-10-01

    At present, dispersion strengthened (DS) copper is being considered as the primary candidate material for the ITER first wall and divertor components. Recently, it was agreed among the ITER parties that a backup alloy should be selected from the two well known precipitation hardened copper alloys, CuCrZr and CuNiBe. It was therefore decided to carry out screening experiments to simulate the effect of bonding and bakeout thermal cycles on microstructure, mechanical properties, and electrical resistivity of CuCrZr and CuNiBe alloys. On the basis of the results of these experiments, one of the two alloys will be selected as a backup material. Tensile specimens of CuCrZr and CuNiBe alloys were given various heat treatments corresponding to solution anneal, prime ageing, and bonding thermal cycle followed by reageing and the reactor bakeout treatment at 623K for 100 hours. Tensile specimens of the DS copper were also given the heat treatment corresponding to the bonding thermal cycle. A number of these heat treated specimens of CuCrZr, CuNiBe, and DS copper were neutron irradiated at 523K to a dose level of {approx}0.3 dpa (NRT) in the DR-3 reactor at Riso. Both unirradiated and irradiated specimens with the various heat treatments were tensile tested at 532K. The dislocation, precipitate and void microstructures and electrical resistivity of these specimens were also determined. Results of these investigations will be reported and discussed in terms of thermal and irradiation stability of precipitates and irradiation-induced precipitation and recovery of dislocation microstructure. Results show that the bonding and bakeout thermal cycles are not likely to have any serious deleterious effects on the performance of these alloys. The CuNiBe alloys were found to be susceptible to radiation-induced embrittlement, however, the exact mechanism is not yet known. It is thought that radiation-induced precipitation and segregation of the beryllium may be responsible.

  19. Analysis of the Thermal Characteristics of Machine Tool Feed System Based on Finite Element Method

    Science.gov (United States)

    Mao, Xiaobo; Mao, Kuanmin; Du, Yikang; Wang, Fengyun; Yan, Bo

    2017-09-01

    The loading of mobile heat source and boundary conditions setting are difficult problems in the analysis of thermal characteristics of machine tools. Taking the machine tool feed system as an example, a novel method for loading of mobile heat source was proposed by establishing a function which was constructed by the heat source and time. The convective heat transfer coefficient is the key parameter of boundary conditions, and it varies with the temperature. In this paper, a model of “variable convection heat transfer coefficient” was proposed, and the setting of boundary conditions of thermal analysis was closer to the real situation. Finally, comparing results of above method and experimental data, the accuracy and validity of this method was proved, meanwhile, the simulation calculation and simulation time was reducing greatly.

  20. Characteristics of Thermally Reduced Graphene Oxide Thin Film as DSSC Counter Electrode

    Science.gov (United States)

    Yuliasari, F.; Aprilia, A.; Syakir, N.; Safriani, L.; Saragi, T.; Risdiana; Hidayat, S.; Bahtiar, A.; Siregar, R.; Fitrilawati

    2017-05-01

    We report characteristics of reduced graphene oxide (RGO) as a counter electrode for dye-sensitized solar cell (DSSC). The RGO thin films were prepared on FTO (Fluorine-doped Tin Oxide) substrates and followed by a reduction process. The RGO film was used as a counter electrode in a DSSC device, with a structure of FTO/TiO2/ruthenium dye/mosalyte/RGO/FTO. UV-Vis measurements show an increasing absorption spectrum of RGO film after thermal reduction process and the FT-IR spectrum confirms a removal of the oxygen containing groups after thermal reduction process. The efficiency (η) of the DSSC that applied RGO film as a counter electrode is 0.96%.

  1. Thermal stability and structural characteristics of PTHF–Mmt organophile nanocomposite

    Directory of Open Access Journals (Sweden)

    Youcef Hattab

    2015-05-01

    The objective of this study is to use organophilized montmorillonites in the presence of monomer tetrahydrofuran to obtain polytétrahydrofuran montmorillonites (PTHF–Mmt of composites by polymerization in situ. The organophilisation of the Mmt is formed by active cationic surface. The obtained results show an increase in the distance inside the reticular in the diffractograms of X-rays (DRX and the appearance of absorption bands of the characteristics of polytétrahydrofuran on the spectra of infrared spectroscopy (IR, which indicate pre-polymerization of tetrahydrofuran in the galleries of clay and, therefore, the obtaining of a nanocomposite. We have also studied the thermal stability of the samples by differential analysis calorimetric (DSC analysis, and we can conclude that the nanocomposites are stabilized thermally by the presence of clay in the matrix.

  2. Heat recovery from a thermal energy storage based on the Ca(OH){sub 2}/CaO cycle

    Energy Technology Data Exchange (ETDEWEB)

    Azpiazu, M.N. [E.T.S. Ingenieros, Bilbao (Spain). Dpto. de Ingenieria Quimica y del Medio Ambiente; Morquillas, J.M. [E.T.S. Ingenieros, Bilbao (Spain). Dpto. de Maquinas y Motores Termicos; Vazquez, A. [E.S. da Marina Civil, La Coruna (Spain). Dpto. de Energia y Propulsion Maritima

    2003-04-01

    Thermal energy storage is very important in many applications related to the use of waste heat from industrial processes, renewable energies or from other sources. Thermochemical storage is very interesting for long-term storage as it can be carried out at room temperature with no energy losses. Dehydration/hydration cycle of Ca(OH){sub 2}/CaO has been applied for thermal energy storage in two types of reactors. One of them was a prototype designed by the authors, and in the other type conventional laboratory glassware was used. Parameters such as specific heats, reaction rate and enthalpy, mass losses and heat release were monitored during cycles. Although in the hydration step water is normally added in vapour phase, liquid water, at 0{sup o}C has been used in these experiences. Results indicated that the energy storage system performance showed no significant differences, when we compared several hydration/dehydration cycles. The selected chemical reaction did not exhibit a complete reversibility because complete Ca(OH){sub 2} dehydration, was not achieved. However the system could be used satisfactorily along 20 cycles at least. Heat recovery experiments showed general system behaviour during the hydration step in both types of reactors. The designed prototype was more efficient in this step. Main conclusions suggested carrying out one complete cycle at a higher dehydration temperature to recover total system reversibility. A modification of the prototype design trying to enhance heat transfer from the Ca(OH){sub 2} bed could also be proposed. (author)

  3. Assessment of Outdoor Thermal Comfort and Wind Characteristics at Three Different Locations in Peninsular Malaysia

    Directory of Open Access Journals (Sweden)

    Hanipah Mohd Hafizal

    2016-01-01

    Full Text Available Urbanization and rapid growth in construction have led to the problems of global warming and urban heat island throughout the world. In order to reduce these problems particularly in hot and humid climatic region, a research on current level of outdoor thermal comfort and wind characteristics based on the local weather conditions around Malaysia should be conducted. This paper reports on the analysis of outdoor thermal comfort level at hottest temperatures and wind characteristics at three locations in Peninsular Malaysia by using hourly climatic data recorded by Malaysian Meteorological Department (MetMalaysia. The level of outdoor thermal comfort was assessed based on the Universal Thermal Climate Index (UTCI. The results showed extreme heat stress conditions have occurred at Alor Setar, Kuantan, and Subang with UTCI values of 51.2°C, 49.7°C, and 49.0°C respectively taking into account only temperature data from the year 2012 to 2014. However, for 20 years data from 1994 to 2014, the calculated UTCI also showed extreme heat stress conditions with their respective values of 49.6°C, 43.8°C, and 49.7°C for Alor Setar, Kuantan, and Subang respectively. Meanwhile, the hourly mean wind speed for three years data at Alor Setar, Kuantan, and Subang, were 1.70m/s, 1.69m/s, and 1.63m/s respectively. The highest mean wind speed of 11.6m/s was observed at Subang, while no wind movement (i.e. 0m/s was considered to be the lowest hourly wind speed for all three locations. The observed prevailing wind direction for all the three locations was from the north (0°. It can be concluded that Peninsular Malaysia is generally facing extreme heat stress problem due to unfavourable climatic conditions.

  4. Influence of thermal and mechanical cycling on the flexural strength of ceramics with titanium or gold alloy frameworks.

    Science.gov (United States)

    Oyafuso, Denise Kanashiro; Ozcan, Mutlu; Bottino, Marco Antonio; Itinoche, Marcos Koiti

    2008-03-01

    The aim of this study was to evaluate the effect of thermal and mechanical cycling alone or in combination, on the flexural strength of ceramic and metallic frameworks cast in gold alloy or titanium. Metallic frameworks (25 mm x 3 mm x 0.5 mm) (N=96) cast in gold alloy or commercial pure titanium (Ti cp) were obtained using acrylic templates. They were airborne particle-abraded with 150 microm aluminum oxide at the central area of the frameworks (8 mm x 3 mm). Bonding agent and opaque were applied on the particle-abraded surfaces and the corresponding ceramic for each metal was fired onto them. The thickness of the ceramic layer was standardized by positioning the frameworks in a metallic template (height: 1 mm). The specimens from each ceramic-metal combination (N=96, n=12 per group) were randomly assigned into four experimental fatigue conditions, namely water storage at 37 degrees C for 24h (control group), thermal cycling (3000 cycles, between 4 and 55 degrees C, dwell time: 10s), mechanical cycling (20,000 cycles under 10 N load, immersion in distilled water at 37 degrees C) and, thermal and mechanical cycling. A flexural strength test was performed in a universal testing machine (crosshead speed: 1.5 mm/min). Data were statistically analyzed using two-way ANOVA and Tukey's test (alpha=0.05). The mean flexural strength values for the ceramic-gold alloy combination (55+/-7.2MPa) were significantly higher than those of the ceramic-Ti cp combination (32+/-6.7 MPa) regardless of the fatigue conditions performed (pgold alloy (52+/-6.6 and 53+/-5.6 MPa, respectively) and ceramic-Ti cp combinations (29+/-6.8 and 29+/-6.8 MPa, respectively) compared to the control group (58+/-7.8 and 39+/-5.1 MPa, for gold and Ti cp, respectively) (pgold alloy frameworks exhibited a residue of ceramic material on the surface in all experimental groups. Mechanical and thermo-mechanical fatigue conditions decreased the flexural strength values for both ceramic-gold alloy and ceramic

  5. RESULTS OF INVESTIGATIONS ON THERMAL CHARACTERISTICS OF AIR HEATER BUNDLE MADE OF BIMETALLIC FINNED TUBES

    Directory of Open Access Journals (Sweden)

    V. B. Kuntysh

    2014-01-01

    Full Text Available The paper presents a scheme and description of a new aerodynamic stand that has a 300x300 mm cross-section operating channel. The stand is used for studying thermal and aerodynamic characteristics of bundles made of finned tubes of actual dimensions in crossflow. The paper provides results of an exploratory test pertaining to heat transfer and resistance of four row staggered bundle made of tubes with aluminium spiral fins having outside diameter of 26 mm which are used in the systems of ventilation, air-conditioning and heating of buildings and also in transport heat exchangers.

  6. Characteristics of Solar Wind Density Depletions During Solar Cycles 23 and 24

    Directory of Open Access Journals (Sweden)

    Keunchan Park

    2017-06-01

    Full Text Available Solar wind density depletions are phenomena that solar wind density is rapidly decreased and keep the state. They are generally believed to be caused by the interplanetary (IP shocks. However, there are other cases that are hardly associated with IP shocks. We set up a hypothesis for this phenomenon and analyze this study. We have collected the solar wind parameters such as density, speed and interplanetary magnetic field (IMF data related to the solar wind density depletion events during the period from 1996 to 2013 that are obtained with the advanced composition explorer (ACE and the Wind satellite. We also calculate two pressures (magnetic, dynamic and analyze the relation with density depletion. As a result, we found total 53 events and the most these phenomena’s sources caused by IP shock are interplanetary coronal mass ejection (ICME. We also found that solar wind density depletions are scarcely related with IP shock’s parameters. The solar wind density is correlated with solar wind dynamic pressure within density depletion. However, the solar wind density has an little anti-correlation with IMF strength during all events of solar wind density depletion, regardless of the presence of IP shocks. Additionally, In 47 events of IP shocks, we find 6 events that show a feature of blast wave. The quantities of IP shocks are weaker than blast wave from the Sun, they are declined in a short time after increasing rapidly. We thus argue that IMF strength or dynamic pressure are an important factor in understanding the nature of solar wind density depletion. Since IMF strength and solar wind speed varies with solar cycle, we will also investigate the characteristics of solar wind density depletion events in different phases of solar cycle as an additional clue to their physical nature.

  7. Underwater Cycle Ergometry: Power Requirements With and Without Diver Thermal Dress

    National Research Council Canada - National Science Library

    Shykoff, B

    2009-01-01

    .... An ongoing problem has been that, although the power requirement of cycling in the water is known to be greater than that in air for the same ergometer setting, the magnitude of the difference...

  8. Limits and Optimization of Power Input or Output of Actual Thermal Cycles

    OpenAIRE

    Emin Açıkkalp; Hasan Yamık

    2013-01-01

    In classical thermodynamic, maximum power obtained from system (or minimum power supplied to system) defined as availability (exergy), but availability term is only used for reversible systems. In reality, there is no reversible system, all systems are irreversible, because reversible cycles doesn’t include constrains like time or size and they operates in quasi-equilibrium state. Purpose of this study is to define limits of the all basic thermodynamic cycles and to provide finite-time exergy...

  9. Irreversibility analysis of hydrogen separation schemes in thermochemical cycles. [Condensation, physical absorption, diffusion, physical adsorption, thermal adsorption, and electrochemical separation

    Energy Technology Data Exchange (ETDEWEB)

    Cox, K.E.

    1978-01-01

    Six processes have been evaluated as regards irreversibility generation for hydrogen separation from binary gas mixtures. The results are presented as a series of plots of separation efficiency against the mol fraction hydrogen in the feed gas. Three processes, condensation, physical absorption and electrochemical separation indicate increasing efficiency with hydrogen content. The other processes, physical and thermal adsorption, and diffusion show maxima in efficiency at a hydrogen content of 50 mol percent. Choice of separation process will also depend on such parameters as condition of feed, impurity content and capital investment. For thermochemical cycles, schemes based on low temperature heat availability are preferable to those requiring a work input.

  10. A review of test results on solar thermal power modules with dish-mounted Stirling and Brayton cycle engines

    Science.gov (United States)

    Jaffe, Leonard D.

    1988-01-01

    This paper presents results of development tests of various solar thermal parabolic dish modules and assemblies that used dish-mounted Brayton or Stirling cycle engines for production of electric power. These tests indicate that early modules achieve net efficiencies up to 29 percent in converting sunlight to electricity, as delivered to the grid. Various equipment deficiencies were observed and a number of malfunctions occurred. The performance measurements, as well as the malfunctions and other test experience, provided information that should be of value in developing systems with improved performance and reduced maintenance.

  11. Integration of photovoltaic and concentrated solar thermal technologies for H2 production by the hybrid sulfur cycle

    Science.gov (United States)

    Liberatore, Raffaele; Ferrara, Mariarosaria; Lanchi, Michela; Turchetti, Luca

    2017-06-01

    It is widely agreed that hydrogen used as energy carrier and/or storage media may significantly contribute in the reduction of emissions, especially if produced by renewable energy sources. The Hybrid Sulfur (HyS) cycle is considered as one of the most promising processes to produce hydrogen through the water-splitting process. The FP7 project SOL2HY2 (Solar to Hydrogen Hybrid Cycles) investigates innovative material and process solutions for the use of solar heat and power in the HyS process. A significant part of the SOL2HY2 project is devoted to the analysis and optimization of the integration of the solar and chemical (hydrogen production) plants. In this context, this work investigates the possibility to integrate different solar technologies, namely photovoltaic, solar central receiver and solar troughs, to optimize their use in the HyS cycle for a green hydrogen production, both in the open and closed process configurations. The analysis carried out accounts for different combinations of geographical location and plant sizing criteria. The use of a sulfur burner, which can serve both as thermal backup and SO2 source for the open cycle, is also considered.

  12. Nanocomposite containing CaF2 nanoparticles: Thermal cycling, wear and long-term water-aging

    Science.gov (United States)

    Weir, Michael D.; Moreau, Jennifer L.; Levine, Eric D.; Strassler, Howard D.; Chow, Laurence C.; Xu, Hockin H. K.

    2012-01-01

    Objectives Fluoride (F) releasing dental restoratives are promising to promote remineralization and combat caries. The objectives of this study were to develop nanocomposite containing calcium fluoride nanoparticles (nCaF2), and to investigate the long-term mechanical durability including wear, thermal-cycling and long-term water-aging behavior. Methods Two types of fillers were used: nCaF2 with a diameter of 53 nm, and glass particles of 1.4 μm. Four composites were fabricated with fillers of: (1) 0% nCaF2 + 65% glass; (2) 10% nCaF2 + 55% glass; (3) 20% nCaF2 + 45% glass; (4) 30% nCaF2 + 35% glass. Three commercial materials were also tested. Specimens were subjected to thermal-cycling between 5 °C and 60 °C for 105 cycles, three-body wear for 4×105 cycles, and water-aging for 2 years. Results After thermal-cycling, the nCaF2 nanocomposites had flexural strengths in the range of 100-150 MPa, five times higher than the 20-30 MPa for resin-modified glass ionomer (RMGI). The wear scar depth showed an increasing trend with increasing nCaF2 filler level. Wear of nCaF2 nanocomposites was within the range of wear for commercial controls. Water-aging decreased the strength of all materials. At 2 years, flexural strength was 94 MPa for nanocomposite with 10% nCaF2, 60 MPa with 20% nCaF2, and 48 MPa with 30% nCaF2. They are 3-6 fold higher than the 15 MPa for RMGI (p nanocomposites appeared dense and solid. Significance Combining nCaF2 with glass particles yielded nanocomposites with long-term mechanical properties that were comparable to those of a commercial composite with little F release, and much better than those of RMGI controls. These strong long-term properties, together with their F release being comparable to RMGI as previously reported, indicate that the nCaF2 nanocomposites are promising for load-bearing and caries-inhibiting restorations. PMID:22429937

  13. Releasing characteristics of phosphorus and other substances during thermal treatment of excess sludge.

    Science.gov (United States)

    Xue, Tao; Huang, Xia

    2007-01-01

    The releasing characteristics of phosphorus, nitrogen compounds, organics, and some metal cations during thermal treatment of excess sludge were investigated. It was found that during heating not only phosphorus, but also nitrogen compounds, organics, and some metal cations could be released in abundance. The maximum orthophosphate (ortho-P) release of about 90 mg/L in concentration was observed at 50 degrees C in 1 h. Except for volatile fatty acids (VFAs), comparatively little total nitrogen (TN), total organic carbon (TOC), and metal cations were released at the same time. Such results might favor further process of phosphorus recovery. VFAs were considerably released only at 50 degrees C. Acetic, butyric, and propionic acid were the most abundant components in turn and their releasing profiles exhibited good linear relationship with time (R2 = 0.9977, 0.9624, and 0.8908, respectively). The concentrations of Mg2+ and K+ increased with time and temperature during thermal treatment, but Ca2+ decreased. The release of Mg2+ and K+ agreed well with TP release (R2 = 0.9892 and 0.9476, respectively). Temperature in the experimental range had very little impact on the linear relationships, especially of Mg2+. Moreover, the parameter of mixed liquor suspended solids (MLSS) was found to be an important factor for thermal sludge treatment as the released ortho-P and total phosphorus (TP) at 50 degrees C increased more than one-fold when MLSS was increased from 4000 to 8000 mg/L.

  14. Experimental study on thermal characteristics of positive leader discharges using Mach-Zehnder interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, X., E-mail: zhouxuan12@mails.thu.edu.cn; Zeng, R.; Zhuang, C.; Chen, S. [Department of Electrical Engineering, Tsinghua University, Beijing 100084 (China)

    2015-06-15

    Leader discharge is one of the main phases in long air gap breakdown, which is characterized by high temperature and high conductivity. It is of great importance to determine thermal characteristics of leader discharges. In this paper, a long-optical-path Mach-Zehnder interferometer was set up to measure the thermal parameters (thermal diameter, gas density, and gas temperature) of positive leader discharges in atmospheric air. IEC standard positive switching impulse voltages were applied to a near-one-meter point-plane air gap. Filamentary channels with high gas temperature and low density corresponding to leader discharges were observed as significant distortions in the interference fringe images. Typical diameters of the entire heated channel range from 1.5 mm to 3.5 mm with an average expansion velocity of 6.7 m/s. In contrast, typical diameters of the intensely heated region with a sharp gas density reduction range from 0.4 mm to 1.1 mm, about one third of the entire heated channel. The radial distribution of the gas density is calculated from the fringe displacements by performing an Abel inverse transform. The typical calculated gas density reduction in the center of a propagating leader channel is 80% to 90%, corresponding to a gas temperature of 1500 K to 3000 K based on the ideal gas law. Leaders tend to terminate if the central temperature is below 1500 K.

  15. Thermal characteristics of spent activated carbon generated from air cleaning units in Korean nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hang Rae; So, Ji Yang [KHNP Central Research Institute, Daejeon (Korea, Republic of)

    2017-06-15

    To identify the feasibility of disposing of spent activated carbon as a clearance level waste, we performed characterization of radioactive pollution for spent activated carbon through radioisotope analysis; results showed that the C-14 concentrations of about half of the spent activated carbon samples taken from Korean NPPs exceeded the clearance level limit. In this situation, we selected thermal treatment technology to remove C-14 and analyzed the moisture content and thermal characteristics. The results of the moisture content analysis showed that the moisture content of the spent activated carbon is in the range of 1.2–23.9 wt% depending on the operation and storage conditions. The results of TGA indicated that most of the spent activated carbon lost weight in 3 temperature ranges. Through py-GC/MS analysis based on the result of TGA, we found that activated carbon loses weight rapidly with moisture desorption reaching to 100°C and desorbs various organic and inorganic carbon compounds reaching to 200°C. The result of pyrolysis analysis showed that the experiment of C-14 desorption using thermal treatment technology requires at least 3 steps of heat treatment, including a heat treatment at high temperature over 850°C, in order to reduce the C-14 concentration below the clearance level.

  16. Thermal characteristics of spent activated carbon generated from air cleaning units in korean nuclear power plants

    Directory of Open Access Journals (Sweden)

    Ji-Yang So

    2017-06-01

    Full Text Available To identify the feasibility of disposing of spent activated carbon as a clearance level waste, we performed characterization of radioactive pollution for spent activated carbon through radioisotope analysis; results showed that the C-14 concentrations of about half of the spent activated carbon samples taken from Korean NPPs exceeded the clearance level limit. In this situation, we selected thermal treatment technology to remove C-14 and analyzed the moisture content and thermal characteristics. The results of the moisture content analysis showed that the moisture content of the spent activated carbon is in the range of 1.2–23.9 wt% depending on the operation and storage conditions. The results of TGA indicated that most of the spent activated carbon lost weight in 3 temperature ranges. Through py-GC/MS analysis based on the result of TGA, we found that activated carbon loses weight rapidly with moisture desorption reaching to 100°C and desorbs various organic and inorganic carbon compounds reaching to 200°C. The result of pyrolysis analysis showed that the experiment of C-14 desorption using thermal treatment technology requires at least 3 steps of heat treatment, including a heat treatment at high temperature over 850°C, in order to reduce the C-14 concentration below the clearance level.

  17. Increased activity of the glucose cycle in the liver: early characteristic of type 2 diabetes.

    OpenAIRE

    Efendić, S; Wajngot, A; Vranić, M

    1985-01-01

    The aims were to assess in the mild, lean, type 2 diabetics the activity of the hepatic futile cycle (glucose cycling) in the basal state and during an infusion of glucose and the overall contribution of futile cycling and the relative contributions of the liver and the periphery to excessive hyperglycemia during a glucose challenge. To determine hepatic futile cycling, we studied seven healthy controls (C) and eight mild, lean, type 2 diabetics with decreased oral glucose tolerance test and ...

  18. Multiple regression models for the prediction of the maximum obtainable thermal efficiency of organic Rankine cycles

    DEFF Research Database (Denmark)

    Larsen, Ulrik; Pierobon, Leonardo; Wronski, Jorrit

    2014-01-01

    to power. In this study we propose four linear regression models to predict the maximum obtainable thermal efficiency for simple and recuperated ORCs. A previously derived methodology is able to determine the maximum thermal efficiency among many combinations of fluids and processes, given the boundary...... conditions of the process. Hundreds of optimised cases with varied design parameters are used as observations in four multiple regression analyses. We analyse the model assumptions, prediction abilities and extrapolations, and compare the results with recent studies in the literature. The models...

  19. Clinical trial on the characteristics of zheng classification of pulmonary diseases based on infrared thermal imaging technology.

    Science.gov (United States)

    Ni, Jin-Xia; Gao, Si-Hua; Li, Yu-Hang; Ma, Shi-Lei; Tian, Tian; Mo, Fang-Fang; Wang, Liu-Qing; Zhu, Wen-Zeng

    2013-01-01

    Zheng classification study based on infrared thermal imaging technology has not been reported before. To detect the relative temperature of viscera and bowels of different syndromes patients with pulmonary disease and to summarize the characteristics of different Zheng classifications, the infrared thermal imaging technology was used in the clinical trial. The results showed that the infrared thermal images characteristics of different Zheng classifications of pulmonary disease were distinctly different. The influence on viscera and bowels was deeper in phlegm-heat obstructing lung syndrome group than in cold-phlegm obstructing lung syndrome group. It is helpful to diagnose Zheng classification and to improve the diagnosis rate by analyzing the infrared thermal images of patients. The application of infrared thermal imaging technology provided objective measures for medical diagnosis and treatment in the field of Zheng studies and provided a new methodology for Zheng classification.

  20. Topology optimization for enhancing the acoustical and thermal characteristics of acoustic devices simultaneously

    Science.gov (United States)

    Oh, Kee Seung; Lee, Jin Woo

    2017-08-01

    In this study, an optimal design method was developed using topology optimization for an acoustic device in the presence of temperature gradient. Although acoustic properties were strongly affected by temperature distribution, many topology optimization problems for optimal acoustic devices were formulated under the assumption that temperature was uniformly distributed in the design domain or that heat transfer through boundaries was negligible. An acoustically optimized topology could negatively influence the heat transfer characteristics of a mechanical device. To figure out this issue, thermo-acoustical topology optimization problems were formulated for an optimal design of the acoustic device. A general form of a finite element equation was developed for acoustical and thermal analyses, and interpolation functions were carefully selected to obtain a black-and-white topology in the final step. Optimal design examples were solved for various acoustical and thermal design requirements, and the physical characteristics of an optimal muffler obtained using the proposed approach in the present study were compared with those of a well-known existing design.

  1. Effect of Gaseous Impurities on Long-Term Thermal Cycling and Aging Properties of Complex Hydrides for Hydrogen Storage

    Energy Technology Data Exchange (ETDEWEB)

    Chandra, Dhanesh [Primary Contact; Lamb, Joshua; Chien, Wen-Ming; Talekar, Anjali; and Pal, Narendra

    2011-03-28

    This program was dedicated to understanding the effect of impurities on Long-Term Thermal Cycling and aging properties of Complex Hydrides for Hydrogen Storage. At the start of the program we found reversibility between Li2NH+LiH LiH+LiNH2 (yielding ~5.8 wt.%H capacity). Then we tested the effect of impurity in H2 gas by pressure cycling at 255°C; first with industrial gas containing ppm levels of O2 and H2O as major impurities. Both these impurities had a significant impact on the reversibility and decreased the capacity by 2.65 wt.%H. Further increase in number of cycles from 500 to 1100 showed only a 0.2 wt%H more weight loss, showing some capacity is still maintained after a significant number of cycles. The loss of capacity is attributed to the formation of ~55 wt% LiH and ~30% Li2O, as major contaminant phases, along with the hydride Li2NH phase; suggesting loss of nitrogen during cycling. The effect of 100 ppm H2O in H2 also showed a decrease of ~2.5 wt.%H (after 560 cycles), and 100ppm O2 in H2; a loss of ~4.1 wt.%. Methane impurity (100 ppm, 100cycles), showed a very small capacity loss of 0.9 wt.%H under similar conditions. However, when Li3N was pressure cycled with 100ppmN2-H2 there were beneficial effects were observed (255oC); the reversible capacity increased to 8.4wt.%H after 853 cycles. Furthermore, with 20 mol.%N2-H2 capacity increased to ~10 wt.%H after 516 cycles. We attribute this enhancement to the reaction of nitrogen with liquid lithium during cycling as the Gibbs free energy of formation of Li3N (Go = -98.7 kJ/mol) is more negative than that of LiH (Go = -50.3 kJ/mol). We propose that the mitigation of hydrogen capacity losses is due to the destabilization of the LiH phase that tends to accumulate during cycling. Also more Li2NH phase was found in the cycled product. Mixed Alanates (3LiNH2:Li3AlH6) showed that 7 wt% hydrogen desorbed under dynamic vacuum. Equilibrium experiments (maximum 12 bar H2) showed up to 4wt% hydrogen reversibly

  2. Numerical Analysis on Thermochemical Characteristics of a Hydrogen Iodine Decomposer in Sulfur-Iodine cycle

    Energy Technology Data Exchange (ETDEWEB)

    Lee, T. H.; Lee, K. Y.; Shin, Y. J. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Choi, J. S.; Choi, J. H. [Korea Maritime and Ocean University, Busan (Korea, Republic of)

    2015-05-15

    In this study, to develop optimum decomposition reactor of HI to apply hydrogen process in thermochemical VHTR-SI cycle, operating characteristics of the HI decomposition reaction were investigated using the CFD code as a commercial program. Several factors, such as hydrogen production, heat of reaction, and temperature distribution, were studied to compare the device performance with that expected for device development. The CFD analysis for HI decomposition simulation was performed by applying the actual operation conditions and HI decomposer design. The hydrogen production depended on the STV ratio. In this study, predicted hydrogen production was 1.12, 1.99, and 3.10 mol/h for STV ratios of 0.3, 0.4, and 0.5, respectively. The hydrogen production at an STV ratio of 0.5 was higher than that at 0.3 by 2 mol/h. The inner temperature of the HI decomposer was studied in the form of contour images at ITC 1-5.

  3. High Spatial Resolution Airborne Multispectral Thermal Infrared Remote Sensing Data for Analysis of Urban Landscape Characteristics

    Science.gov (United States)

    Quattrochi, Dale A.; Luvall, Jeffrey C.; Estes, Maurice G., Jr.; Arnold, James E. (Technical Monitor)

    2000-01-01

    We have used airborne multispectral thermal infrared (TIR) remote sensing data collected at a high spatial resolution (i.e., 10m) over several cities in the United States to study thermal energy characteristics of the urban landscape. These TIR data provide a unique opportunity to quantify thermal responses from discrete surfaces typical of the urban landscape and to identify both the spatial arrangement and patterns of thermal processes across the city. The information obtained from these data is critical to understanding how urban surfaces drive or force development of the Urban Heat Island (UHI) effect, which exists as a dome of elevated air temperatures that presides over cities in contrast to surrounding non-urbanized areas. The UHI is most pronounced in the summertime where urban surfaces, such as rooftops and pavement, store solar radiation throughout the day, and release this stored energy slowly after sunset creating air temperatures over the city that are in excess of 2-4'C warmer in contrast with non-urban or rural air temperatures. The UHI can also exist as a daytime phenomenon with surface temperatures in downtown areas of cities exceeding 38'C. The implications of the UHI are significant, particularly as an additive source of thermal energy input that exacerbates the overall production of ground level ozone over cities. We have used the Airborne Thermal and Land Applications Sensor (ATLAS), flown onboard a Lear 23 jet aircraft from the NASA Stennis Space Center, to acquire high spatial resolution multispectral TIR data (i.e., 6 bandwidths between 8.2-12.2 (um) over Huntsville, Alabama, Atlanta, Georgia, Baton Rouge, Louisiana, Salt Lake City, Utah, and Sacramento, California. These TIR data have been used to produce maps and other products, showing the spatial distribution of heating and cooling patterns over these cities to better understand how the morphology of the urban landscape affects development of the UHI. In turn, these data have been used

  4. Experimental investigation of thermal characteristics of synthetic jet generator's diaphragm with piezoelectric actuator

    Science.gov (United States)

    Rimasauskiene, Ruta; Rimasauskas, Marius; Mieloszyk, Magdalena; Wandowski, Tomasz; Malinowski, Pawel; Ostachowicz, Wieslaw

    2014-05-01

    An experimental analysis of the thermal characteristics of two different diaphragms of the synthetic jet generator was presented in this paper. It is extremely important to study temperature characteristics of the components with piezoelectric actuators working in various modes. Often piezoelectric actuators are used aiming to obtain maximum displacements that are possible when a piezoelectric actuator operates under maximum excitation voltage and often at the first resonance frequency. The theory suggests that working in such modes extremely increases temperature of the piezoelectric elements and it can reach maximum point. High temperatures might cause deformation or other changes of mechanical properties of the other components. This might influence the life time and operational characteristics of the synthetic jet generator. The main task of this work was to find the best working conditions for the synthetic jet generator. Dynamic characteristics of the diaphragm with piezoelectric material were measured using non-contact measuring equipment laser vibrometer Polytec® PSV 400. Temperatures of the piezoelectric diaphragms working at different resonance frequencies were measured with Fiber Bragg Grating (FBG) sensor. Experimental results of two different piezoelectric diaphragms were presented in this article. The best working conditions for synthetic jet generator were chosen.

  5. Life cycle cost optimization of buildings with regard to energy use, thermal indoor environment and daylight

    DEFF Research Database (Denmark)

    Nielsen, Toke Rammer; Svendsen, Svend

    2002-01-01

    Buildings represent a large economical investment and have long service lives through which expenses for heating, cooling, maintenance and replacement depends on the chosen building design. Therefore, the building cost should not only be evaluated by the initial investment cost but rather...... by the life cycle cost taking all expenses in the buildings service life into consideration. Also the performance of buildings is important as the performance influences the comfort of the occupants, heating demand etc. Different performance requirements are stated in building codes, standards...... and by the customer. The influence of different design variables on life cycle cost and building performance is very complicated and the design variables can be combined in an almost unlimited number of ways. Optimization can be applied to achieve a building design with low life cycle cost and good performance...

  6. Amplitude of the diurnal temperature cycle as observed by thermal infrared and microwave radiometers

    Science.gov (United States)

    Land surface temperature (LST) is a key input to physically-based retrieval algorithms of hydrological states and fluxes, and global measurements of LST are provided by many satellite platforms. Passive microwave (MW) observations offer an alternative to conventional thermal infrared (TIR) LST retri...

  7. Thermophysical characterization and thermal cycling stability of two TCM: CaCl2 and zeolite

    NARCIS (Netherlands)

    Barreneche, C.; Fernández, A.I.; Cabeza, L.F.; Cuypers, R.

    2015-01-01

    At this moment, the global energy consumption in buildings is around 40% of the total energy consumption in developed countries. Thermal energy storage (TES) is presented as one way to address this energy-related problem proposing an alternative to reduce the gap between energy supply and energy

  8. Characteristic Analysis of Vuilleumier Cycle Machine and Its Application to Air-Conditioning Heat Pump

    Science.gov (United States)

    Sekiya, Hiroshi

    The Vuilleumier (VM) cycle machine is realized as a regenerative and external-combustion machine in the same way as a Stirling (ST) cycle machine. In the VM cycle, heat enters the cyc1e from hot and cold temperature heat sources and is delivered to an intermediate temperature heat source by a working gas. In consequence of the theoretical cycle, output power is not produced. The VM cycle machine is made of the same elements as the ST cycle machine and also closely connected with the ST cycle machine in its working principle. By means of analysis using an isothermal model, it is found that the VM cycle machine is internally divided into a ST engine and a ST refrigerator. In addition, the calculated results by a simulation model based on a so-called 3rd-order method clarify that the VM cycle machine has different featuers from the ST cycle macine with regard to the working gas behavior, the energy flow and the performance depending on the revolution speed. Application of the VM cycle machine to a heat pump for heating and cooling takes effect on the environment and energy problems arising on a terrestrial scale. In reacent years, research and development have been making on the VM haet pumps.

  9. Study on performances of colorless and transparent shape memory polyimide film in space thermal cycling, atomic oxygen and ultraviolet irradiation environments

    Science.gov (United States)

    Gao, Hui; Lan, Xin; Liu, Liwu; Xiao, Xinli; Liu, Yanju; Leng, Jinsong

    2017-09-01

    Shape memory polymers with high glass transition temperature (HSMPs) and HSMP-based deployable structures and devices, which can bear harsh operation conditions for durable applications, have attracted more and more interest in recent years. In this article, colorless and transparent shape memory polyimide (SMCTPI) films were subjected to simulated vacuum thermal cycling, atomic oxygen (AO) and ultraviolet (UV) irradiation environments up to 600 h, 556 h and 600 h for accelerated irradiation. The glass transition temperature (T g) determined by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) had no obvious changes after being irradiated by varying amounts of thermal cycling, AO and UV irradiation dose. After being irradiated by 50 thermal cycles, 10 × 1021 atoms cm-2 AO irradiation and 3000 ESH UV irradiation, shape recovery behaviors of SMCTPI films also had no obvious damage even if they experienced 30 shape memory cycles, while the surface morphologies and optical properties were seriously destroyed by AO irradiation, as compared with thermal cycling and UV irradiation. The tensile strength could separately maintain 122 MPa, 120 MPa and 70 MPa after 50 thermal cycles, 10 × 1021 atoms cm-2 AO irradiation and 3000 ESH UV irradiation, which shows great potential for use in aerospace structures and devices.

  10. Flow boiling heat transfer and pressure drop characteristics of R134a, R1234yf and R1234ze in a plate heat exchanger for organic Rankine cycle units

    DEFF Research Database (Denmark)

    Zhang, Ji; Desideri, Adriano; Kærn, Martin Ryhl

    2017-01-01

    . This paper is aimed at obtaining flow boiling heat transfer and pressure drop characteristics in a plate heat exchanger under the working conditions prevailing in the evaporator of organic Rankine cycle units. Two hydrofluoroolefins R1234yf and R1234ze, and one hydrofluorocarbon R134a, were selected......The optimal design of the evaporator is one of the key issues to improve the efficiency and economics of organic Rankine cycle units. The first step in studying the evaporator design is to understand the thermal-hydraulic performance of the working fluid in the evaporator of organic Rankine cycles......, respectively. The working conditions covered relatively high saturation temperatures (corresponding reduced pressures of 0.35-0.74), which are prevailing in organic Rankine cycles yet absent in the open literature. The experimental data were compared with existing correlations, and new correlations were...

  11. Characteristics and thermal behavior analysis of lithium-ion batteries for application in hybrid locomotives

    Science.gov (United States)

    Chatterjee, Krishnashis

    The locomotive industry accounts for 2.5 % of the total fuel consumption in the US. Thus the necessity for reducing fuel consumption and emissions led to the development of the concept of hybrid locomotive which is dual powered by the diesel engine and electric motors. But the energy dissipated in braking such a locomotive in a year is enough to power over 9100 average US households over the same period of time. Recovering this energy using regenerative braking system and storing it in a electric battery is of great interest among researchers for improving overall efficiency and reducing consumption of fuels. In the present study, LiFePO4 batteries, a type of the state-of-art lithium-ion batteries, have been tested under different environmental and load conditions. Environmental temperatures were varied to analyze their effects on the charging and discharging patterns of the battery by using the CADEX battery analyzer in order to find the temperature range for optimum battery performance. The fluctuations of temperature of the battery surface were monitored along the length of the tests, using Infra-Red imaging and thermocouple probes at different points on the battery surface. Both battery performance characteristics and the variation of the battery surface temperature were also recorded for different load cycles in order to get a comprehensive picture of the heat generation and its effect on the behavior of the battery under different load conditions. Lastly a practical Load Cycle analysis of the battery has been performed which gave a picture of the heat generated by the battery and also the performance characteristics as it is subjected to a practical Load Cycle.

  12. Characteristics of Non-Ferrous Metal Alloys as Determined by Low-Cycle Fatigue Test under Variable Loads

    Directory of Open Access Journals (Sweden)

    Maj M.

    2014-03-01

    Full Text Available The paper presents the results of comparative tests of the fatigue properties conducted on two non-ferrous alloys designated as Al 6082 and Al 7075 which, due to the satisfactory functional characteristics, are widely used as engineering materials. The fatigue tests were carried out using a proprietary, modified low cycle test (MLCF. Particular attention was paid to the fatigue strength exponent b and fatigue ductility exponent c. Based on the tests carried out, the results comprised within the range defined by the literature were obtained. These results prove a satisfactory sensitivity of the method applied, its efficiency, the possibility of conducting tests in a fully economical way and above all the reliability of the obtained results of the measurements. Thus, the thesis has been justified that the modified low cycle fatigue test (MLCF can be recommended as a tool used in the development of alloy characteristics within the range of low-cycle variable loads

  13. COMBINED CYCLE GAS TURBINE FOR THERMAL POWER STATIONS: EXPERIENCE IN DESIGNING AND OPERATION, PROSPECTS IN APPLICATION

    Directory of Open Access Journals (Sweden)

    N. V. Karnitsky

    2014-01-01

    Full Text Available The paper has reviewed main world tendencies in power consumption and power system structure. Main schemes of combined cycle gas turbines have been considered in the paper. The paper contains an operational analysis of CCGT blocks that are operating within the Belarusian energy system. The analysis results have been given in tables showing main operational indices of power blocks

  14. The Effect of Thermal Cycling on the Surface Roughness of Dental Casting Investments.

    Science.gov (United States)

    1991-05-01

    refractory materials, usually silica as either quartz or cristobalite , and a binder that was a gypsum product in the form of plaster or stone. The...refractory materials <pand upon heating because of the thermal expansion of the material and the change in the crystalline state (alpha to beta ). Of the four...common stable forms of silica (quartz, tridymite, cristobalite , and fused or vitreous silica), cristobalite has the greatest expansion and lowest

  15. Technical Feasibility Study of Thermal Energy Storage Integration into the Conventional Power Plant Cycle

    OpenAIRE

    Wojcik, Jacek D.; Wang, Jihong

    2017-01-01

    The current load balance in the grid is managed mainly through peaking fossil-fuelled power plants that respond passively to the load changes. Intermittency, which comes from renewable energy sources, imposes additional requirements for even more flexible and faster responses from conventional power plants. A major challenge is to keep conventional generation running closest to the design condition with higher load factors and to avoid switching off periods if possible. Thermal energy storage...

  16. Thermophysical characterization and thermal cycling stability of two TCM: CaCl2 and zeolite

    OpenAIRE

    Barreneche Güerisoli, Camila; Fernández Renna, Ana Inés; Cabeza, Luisa F.; Cuypers, Ruud

    2015-01-01

    At this moment, the global energy consumption in buildings is around 40% of the total energy consumption in developed countries. Thermal energy storage (TES) is presented as one way to address this energyrelated problem proposing an alternative to reduce the gap between energy supply and energy demand. One way to store energy is using thermochemical materials (TCM). These types of materials allow accumulating energy through a chemical process at low temperature, almost without hea...

  17. Sensitivity analysis of a community solar system using annual cycle thermal energy storage

    Science.gov (United States)

    Baylin, F.; Monte, R.; Sillman, S.

    The objective of this research is to assess the sensitivity of design parameters for a community solar heating system having annual thermal energy storage to factors including climate, building type, community size and collector type and inclination. The system under consideration uses a large, water-filled, concrete-constructed tank for providing space heating and domestic hot water (DHW). This presentation outlines results and conclusions about system sizing; a system design study and economic analysis are underway.

  18. Power plant design with a combined cycle and double concentrated solar thermal power sources

    OpenAIRE

    Vidal i Parreu, Arnau

    2010-01-01

    The electricity has become an indispensable element of today’s society. Demand is growing continuously and the production is still based on limited sources of energy such as coal and petroleum derivate products. Environmental issues, such as global warming, and the uncertainty about the quantity of the conventional fossil fuels are forcing suppliers to find new solutions for the near future. In this assignment, concentrated solar thermal technologies for electricity generation could pla...

  19. Analyze and Improve Lifetime in 3L-NPC Inverter from Power Cycle and Thermal Balance

    DEFF Research Database (Denmark)

    Chen, Quan; Chen, Zhe; Wang, Qunjing

    2014-01-01

    Three-level Neutral-point-clamped (3L-NPC) topology is becoming a realistic alternative to the conventional one in high-voltage and high-power application. Studies show that the power cycling mean time to failure (MTTF) of the semiconductor bond wire in 3L-NPC inverter system may be very short...... and load voltage is applied to reduce power cycle and switching losses. And then, three-level active neutral point-clamped topology is taken into account to wake the most thermo stressed device. In order to validate the improve lifetime method in this paper, a 2MW 3L-NPC converter used in wind energy has...... under some common conditions. Firstly, this paper shows the impact of some key parameters on power electronic system lifetime according the analysis of semiconductor failure mechanism. Secondly, a switching frequency reduction method based on the position relationship between the flowing current...

  20. Thermal and Cycle-Life Behavior of Commercial Li-ion and Li-Polymer Cells

    Science.gov (United States)

    Zimmerman, Albert H.; Quinzio, M. V.

    2001-01-01

    Accelerated and real-time LEO cycle-life test data will be presented for a range of commercial Li-ion and Li-polymer (gel type) cells indicating the ranges of performance that can be obtained, and the performance screening tests that must be done to assure long life. The data show large performance variability between cells, as well as a highly variable degradation signature during non-cycling periods within the life tests. High-resolution Dynamic Calorimetry data will be presented showing the complex series of reactions occurring within these Li cells as they are cycled. Data will also be presented for cells being tested using an Adaptive Charge Control Algorithm (ACCA) that continuously adapts itself to changes in cell performance, operation, or environment to both find and maintain the optimum recharge over life. The ACCA has been used to prevent all unneeded overcharge for Li cells, NiCd cells and NiH2 cells. While this is important for all these cell types, it is most critical for Li-ion cells, which are not designed with electrochemical tolerance for overcharge.

  1. Relieving thermal discomfort: Effects of sprayed L-menthol on perception, performance, and time trial cycling in the heat.

    Science.gov (United States)

    Barwood, M J; Corbett, J; Thomas, K; Twentyman, P

    2015-06-01

    L-menthol stimulates cutaneous thermoreceptors and induces cool sensations improving thermal comfort, but has been linked to heat storage responses; this could increase risk of heat illness during self-paced exercise in the heat. Therefore, L-menthol application could lead to a discrepancy between behavioral and autonomic thermoregulatory drivers. Eight male participants volunteered. They were familiarized and then completed two trials in hot conditions (33.5 °C, 33% relative humidity) where their t-shirt was sprayed with CONTROL-SPRAY or MENTHOL-SPRAY after 10 km (i.e., when they were hot and uncomfortable) of a 16.1-km cycling time trial (TT). Thermal perception [thermal sensation (TS) and comfort (TC)], thermal responses [rectal temperature (Trec ), skin temperature (Tskin )], perceived exertion (RPE), heart rate, pacing (power output), and TT completion time were measured. MENTHOL-SPRAY made participants feel cooler and more comfortable and resulted in lower RPE (i.e., less exertion) yet performance was unchanged [TT completion: CONTROL-SPRAY 32.4 (2.9) and MENTHOL-SPRAY 32.7 (3.0) min]. Trec rate of increase was 1.40 (0.60) and 1.45 (0.40) °C/h after CONTROL-SPRAY and MENTHOL-SPRAY application, which were not different. Spraying L-menthol toward the end of self-paced exercise in the heat improved perception, but did not alter performance and did not increase heat illness risk. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  2. Influence of thermal hydrolysis pretreatment on organic transformation characteristics of high solid anaerobic digestion.

    Science.gov (United States)

    Han, Yun; Zhuo, Yang; Peng, Dangcong; Yao, Qian; Li, Huijuan; Qu, Qiliang

    2017-11-01

    The study evaluated the influence of thermal hydrolysis pretreatment (THP) on anaerobic digestion (AD) ability of high solid sludge. The transformation characteristics of organics during the THP+AD process of dewatering sludge from wastewater treatment plant was investigated using a lab-scale THP reactor and four anaerobic digesters. The reduction efficiency of volatile suspended solids using THP+AD exceeded 49%. The acceleration of biogas production during AD was due to the enhancement of protein hydrolysis and acidogenesis by THP. THP had only minimal influence on the improvement of carbohydrate acidogenesis. The hydrolysis of poly phosphates was likely the main reaction of phosphorus transformation. Biochemical generation of sulfide and ammonia nitrogen occurred during the acidogenesis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Assessment of thermal effects on the free vibration characteristics of composite beams

    Energy Technology Data Exchange (ETDEWEB)

    Ergun, Emin; Alkan, Veysel [Pamukkale Univ., Denizil (Turkey). Dept. of Mechanical Engineering

    2014-02-01

    In this study, thermal effects on the free vibration characteristics of composite beams are studied for different temperatures and boundary conditions by using numerical and experimental techniques. Different ply angles, stacking sequences and specimen thickness are also considered. The comparison revealed a good agreement between numerical and experimental results. It is also concluded that regardless of the type of boundary condition and thickness, natural frequencies are decreased with increasing temperature. In addition, a minimum natural frequency value occurs in the natural frequency-ply angle graph at 60 ply angle for all considered temperatures. It can also be stated that the natural frequencies of the composite beams can be adjusted by controlling the temperature as well as the stacking sequences. (orig.)

  4. Folic acid supplement use and menstrual cycle characteristics: a cross-sectional study of Danish pregnancy planners.

    Science.gov (United States)

    Cueto, Heidi T; Riis, Anders H; Hatch, Elizabeth E; Wise, Lauren A; Rothman, Kenneth J; Sørensen, Henrik T; Mikkelsen, Ellen M

    2015-10-01

    To examine the association between folic acid (FA) supplementation obtained through either single FA tablets or multivitamins (MVs) and menstrual cycle characteristics among 5386 women aged 18-40 years, enrolled in an Internet-based study of Danish women attempting pregnancy during 2007-2011. In a cross-sectional study, we used logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the associations of FA supplementation with menstrual cycle regularity; short (cycle lengths; and duration and intensity of menstrual bleeding. Compared with nonuse, FA supplementation was associated with reduced odds of short cycle length (OR = 0.80, 95% CI: 0.68-0.94) and a trend toward increased odds of very long cycle length (OR = 1.21, 95% CI: 0.87-1.68) compared with cycle length of 27-29 days. The inverse association with short cycle length was stronger among 18- to 30-year-old women (OR = 0.68, 95% CI: 0.53-0.87), nulliparous women (OR = 0.66, 95% CI: 0.52-0.84), and women who used both FA and MVs (OR = 0.75, 95% CI: 0.60-0.95). We found no clear association between FA supplementation and cycle regularity and duration and intensity of menstrual bleeding. FA supplementation was inversely associated with short menstrual cycle length. This association was strongest among women aged 18-30 years, nulliparous women, and women who used both FA and MVs. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. Analysis of clinically relevant mechanical and thermal characteristics of titanium foam spinal implants during drilling.

    Science.gov (United States)

    Ito, Kiyoshi; Horiuchi, Tetsuyoshi; Murata, Takahiro; Hongo, Kazuhiro

    2015-09-01

    Although high biocompatibility promotes the use of titanium (Ti) alloy in spinal implants, this material shows high stiffness, which is an issue for removal by drilling. The recently developed, porous Ti foam implants, which have shown enhanced osteoformation, may overcome this flaw. Thus, this study aimed to compare the mechanical and thermal characteristics of Ti-foam (80 % porosity) and conventional Ti alloy (0 % porosity) implants drilled in clinically relevant conditions. Mechanical properties were analyzed by measuring axial and torque forces using a pressure sensor with a drill of 2.5-mm diameter at a rotation frequency of 20 Hz. Thermography was used to evaluate the heat generated by a diamond burr attached to a high-speed (80,000 rpm) drill. The torque and axial strengths of Ti foam (13.63 ± 1.43 and 82.60 ± 7.78 N, respectively) were significantly lower (P = 0.001) than those of Ti alloy (73.58 ± 13.60 and 850.72 ± 146.99 N, respectively). Furthermore, irrigation reduced the area of local heating for Ti foam to 56-82 % of that for Ti alloy, indicating lower thermal conductivity. These data suggest that the use of Ti foam implants may be advantageous in cases with a probability of implant drilling in the future.

  6. Implications of Weak Link Effects on Thermal Characteristics of Transition-Edge Sensors

    Science.gov (United States)

    Bailey, C. N.; Adams, J. S.; Bandler, S. R.; Brekosky, R. P.; Chevenak, J. A.; Eckart, M. E.; Finkbeiner, F. M.; Kelley, R. L.; Kally, D. P.; Kilbourne, C. A.; hide

    2012-01-01

    Weak link behavior in transition-edge sensor (TES) microcalorimeters creates the need for a more careful characterization of a device's thermal characteristics through its transition. This is particularly true for small TESs where a small change in the bias current results in large changes in effective transition temperature. To correctly interpret measurements, especially complex impedance, it is crucial to know the temperature-dependent thermal conductance, G(T), and heat capacity, C(T), at each point through the transition. We present data illustrating these effects and discuss how we overcome the challenges that are present in accurately determining G and T from I-V curves. We also show how these weak link effects vary wi.th TES size. Additionally, we use this improVed understanding of G(T) to determine that, for these TES microcalorimeters. Kaptiza boundary resistance dominates the G of devices with absorbers while the electron-phonon coupling also needs to be considered when determining G for devices without absorbers

  7. Investigation of structural modification and thermal characteristics of lignin after heat treatment.

    Science.gov (United States)

    Kim, Jae-Young; Hwang, Hyewon; Oh, Shinyoung; Kim, Yong-Sik; Kim, Ung-Jin; Choi, Joon Weon

    2014-05-01

    Milled wood lignin was subjected to heat treatment between 150 and 300°C to understand the pattern of its structural modification and thermal properties. When the temperature was elevated with interval of 50°C, the color of the lignin became dark brown and the lignin released various forms of phenols from terminal phenolic groups in the lignin, leading to two physical phenomena: (1) gradual weight loss of the lignin, up to 19% based on dry weight and (2) increase in the carbon content and decrease in the oxygen content. Nitrobenzene oxidation and (13)C NMR analyses confirmed a cleavage of β-O-4 linkage (depolymerization) and reduction of methoxyl as well as phenolic hydroxyl group were also characteristic in the lignin structure during heat treatment. Simultaneously with lignin depolymerization, GPC analysis provided a possibility that condensation between lignin fragments could also occur during heat treatment. TGA/DTG/DSC data revealed that thermal stability of lignin obviously increased after heat treatment, implicating the structural rearrangement of lignin to reduction of β-O-4 linkage as well as accumulation of CC bonds. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Micro-Encapsulated Phase Change Materials: A Review of Encapsulation, Safety and Thermal Characteristics

    Directory of Open Access Journals (Sweden)

    Ahmed Hassan

    2016-10-01

    Full Text Available Phase change materials (PCMs have been identified as potential candidates for building energy optimization by increasing the thermal mass of buildings. The increased thermal mass results in a drop in the cooling/heating loads, thus decreasing the energy demand in buildings. However, direct incorporation of PCMs into building elements undermines their structural performance, thereby posing a challenge for building integrity. In order to retain/improve building structural performance, as well as improving energy performance, micro-encapsulated PCMs are integrated into building materials. The integration of microencapsulation PCMs into building materials solves the PCM leakage problem and assures a good bond with building materials to achieve better structural performance. The aim of this article is to identify the optimum micro-encapsulation methods and materials for improving the energy, structural and safety performance of buildings. The article reviews the characteristics of micro-encapsulated PCMs relevant to building integration, focusing on safety rating, structural implications, and energy performance. The article uncovers the optimum combinations of the shell (encapsulant and core (PCM materials along with encapsulation methods by evaluating their merits and demerits.

  9. Effect of CuO nanolubricant on compressor characteristics and performance of LPG based refrigeration cycle: experimental investigation

    Science.gov (United States)

    Kumar, Ravinder; Singh, Jagdev; Kundal, Pankaj

    2017-11-01

    Refrigeration, Ventilation and Air Conditioning system is the largest reason behind the increasing demand of energy consumption in the world and saving that energy through some innovative methods becomes a large issue for the researchers. Compressor is a primary component of the refrigeration cycle. The application of nanoparticles in refrigeration cycle overcomes the energy consumption issue by improving the compressor suction and discharge characteristics. In this paper, an experimental study is carried out to investigate the effect of copper oxide (CuO) nanoparticles on different parameters of the refrigeration cycle. CuO particles are appended with the system refrigerant through lubricating oil of the compressor. Further, the viscosity measurements and friction coefficient analysis of compressor lubricant for different fractions of nanoparticles has been investigated. The results showed that both the suction and discharge characteristics of the compressor were enhanced with the utilization of nanolubricant in LPG based refrigeration cycle. Nanoparticles additive in lubricant increases the viscosity which lead to a significant decrease in friction coefficient. The COP of the cycle was improved by 46%, as the energy consumption of the compressor was decreased by 7%.

  10. Characteristics of the limit cycle of a reciprocating quantum heat engine.

    Science.gov (United States)

    Feldmann, Tova; Kosloff, Ronnie

    2004-10-01

    After starting a reciprocating heat engine it eventually settles to a stable mode of operation. A first principle quantum heat engine also approaches this stable limit cycle. The studied engine is based on a working medium consisting of an ensemble of quantum systems composed of two coupled spins. A four-stroke cycle of operation is studied, with two isochore branches where heat is transferred from the hot/cold baths and two adiabats where work is exchanged. The dynamics is generated by a completely positive map. It has been shown that the performance of this model resembles an engine with intrinsic friction. The quantum conditional entropy is employed to prove the monotonic approach to a limit cycle. Other convex measures such as the quantum distance display the same monotonic approach. The equations of motion of the engine are solved for the different branches and are combined to a global propagator that relates the state of the engine in the beginning of the cycle to the state after one period of operation of the cycle. The eigenvalues of the propagator define the rate of relaxation toward the limit cycle. A longitudinal and transverse mode of approach to the limit cycle is thus identified. The entropy balance is used to explore the necessary conditions which lead to a stable limit cycle. The phenomena of friction can be identified with a zero change in the von Neumann entropy of the working medium.

  11. Improving fuel cycle design and safety characteristics of a gas cooled fast reactor

    NARCIS (Netherlands)

    van Rooijen, W.F.G.

    2006-01-01

    This research concerns the fuel cycle and safety aspects of a Gas Cooled Fast Reactor, one of the so-called "Generation IV" nuclear reactor designs. The Generation IV Gas Cooled Fast Reactor uses helium as coolant at high temperature. The goal of the GCFR is to obtain a "closed nuclear fuel cycle",

  12. [Comparative characteristics of the sleep-wakefulness cycle of hibernating and non-hibernating mammals].

    Science.gov (United States)

    Karmanova, I G; Bogoslovskiĭ, M M; Andreeva, L V

    1987-05-01

    Wakefulness-sleep cycles compared in rats and European hedgehogs revealed differences in quantitative representation of phases in hibernating and non-hibernating mammals. The data obtained suggest a higher level of the wakefulness-sleep cycle organization in rats as compared with European hedgehogs.

  13. Influence of Thermal Cycling on Flexural Properties and Simulated Wear of Computer-aided Design/Computer-aided Manufacturing Resin Composites.

    Science.gov (United States)

    Tsujimoto, A; Barkmeier, W W; Takamizawa, T; Latta, M A; Miyazaki, M

    The purpose of this study was to evaluate the influence of thermal cycling on the flexural properties and simulated wear of computer-aided design/computer-aided manufacturing (CAD/CAM) resin composites. The six CAD/CAM resin composites used in this study were 1) Lava Ultimate CAD/CAM Restorative (LU); 2) Paradigm MZ100 (PM); 3) CERASMART (CS); 4) Shofu Block HC (SB); 5) KATANA AVENCIA Block (KA); and 6) VITA ENAMIC (VE). Specimens were divided randomly into two groups, one of which was stored in distilled water for 24 hours, and the other of which was subjected to 10,000 thermal cycles. For each material, 15 specimens from each group were used to determine the flexural strength and modulus according to ISO 6872, and 20 specimens from each group were used to examine wear using a localized wear simulation model. The test materials were subjected to a wear challenge of 400,000 cycles in a Leinfelder-Suzuki device (Alabama machine). The materials were placed in custom-cylinder stainless steel fixtures, and simulated localized wear was generated using a stainless steel ball bearing (r=2.387 mm) antagonist in a water slurry of polymethyl methacrylate beads. Simulated wear was determined using a noncontact profilometer (Proscan 2100) with Proscan and AnSur 3D software. The two-way analysis of variance of flexural properties and simulated wear of CAD/CAM resin composites revealed that material type and thermal cycling had a significant influence (p0.05) between the two factors. The flexural properties and maximum depth of wear facets of CAD/CAM resin composite were different (pinfluenced (p>0.05) by thermal cycling, except in the case of VE. The volume losses in wear facets on LU, PM, and SB after 10,000 thermal cycles were significantly higher (pinfluenced by thermal cycling.

  14. Characteristics of Turbulent Airflow Deduced from Rapid Surface Thermal Fluctuations: An Infrared Surface Anemometer

    Science.gov (United States)

    Aminzadeh, Milad; Breitenstein, Daniel; Or, Dani

    2017-12-01

    The intermittent nature of turbulent airflow interacting with the surface is readily observable in fluctuations of the surface temperature resulting from the thermal imprints of eddies sweeping the surface. Rapid infrared thermography has recently been used to quantify characteristics of the near-surface turbulent airflow interacting with the evaporating surfaces. We aim to extend this technique by using single-point rapid infrared measurements to quantify properties of a turbulent flow, including surface exchange processes, with a view towards the development of an infrared surface anemometer. The parameters for the surface-eddy renewal (α and β ) are inferred from infrared measurements of a single-point on the surface of a heat plate placed in a wind tunnel with prescribed wind speeds and constant mean temperatures of the surface. Thermally-deduced parameters are in agreement with values obtained from standard three-dimensional ultrasonic anemometer measurements close to the plate surface (e.g., α = 3 and β = 1/26 (ms)^{-1} for the infrared, and α = 3 and β = 1/19 (ms)^{-1} for the sonic-anemometer measurements). The infrared-based turbulence parameters provide new insights into the role of surface temperature and buoyancy on the inherent characteristics of interacting eddies. The link between the eddy-spectrum shape parameter α and the infrared window size representing the infrared field of view is investigated. The results resemble the effect of the sampling height above the ground in sonic anemometer measurements, which enables the detection of larger eddies with higher values of α . The physical basis and tests of the proposed method support the potential for remote quantification of the near-surface momentum field, as well as scalar-flux measurements in the immediate vicinity of the surface.

  15. Effect of weld thermal cycle on helium bubble formation in stainless steel

    Science.gov (United States)

    Kano, F.; Nakahigashi, S.; Nakamura, H.; Uesugi, N.; Mitamura, T.; Terasawa, M.; Irie, H.; Fukuya, K.

    1998-10-01

    Helium bubble structure was examined on a helium-implanted stainless steel after applying two kinds of heat input. Helium ions were implanted on Type 304 stainless steel at 573 K from 2 to 200 appm to a peak depth of 0.5 μm from the surface. After that, weld thermal history was applied by an electron beam. The cooling rates were selected to be 370 and 680 K/s from 1023 to 773 K. TEM observation revealed that nucleation and growth of helium bubbles were strongly dependent on the cooling rate after welding and the helium concentration.

  16. Study of Diurnal Cycle Variability of Planetary Boundary Layer Characteristics over the Red Sea and Arabian Peninsula

    KAUST Repository

    Li, Weigang

    2012-07-01

    This work is aimed at investigating diurnal cycle variability of the planetary boundary layer characteristics over the Arabian Peninsula and the Red Sea region. To fulfill this goal the downscaling simulations are performed using Weather Research and Forecasting (WRF) model. We analyze planetary boundary layer height, latent and sensible heat fluxes, and surface air temperature. The model results are compared with observations in different areas, for different seasons, and for different model resolutions. The model results are analyzed in order to better quantify the diurnal cycle variability over the Arabian Peninsula and the Red Sea. The specific features of this region are investigated and discussed.

  17. The Annual Cycle of Water Vapor on Mars as Observed by the Thermal Emission Spectrometer

    Science.gov (United States)

    Smith, Michael D.; Vondrak, Richard R. (Technical Monitor)

    2001-01-01

    Spectra taken by the Mars Global Surveyor Thermal Emission Spectrometer (TES) have been used to monitor the latitude, longitude, and seasonal dependence of water vapor for over one full Martian year (March 1999-March 2001). A maximum in water vapor abundance is observed at high latitudes during mid-summer in both hemispheres, reaching a maximum value of approximately 100 pr-micrometer in the north and approximately 50 pr-micrometer in the south. Low water vapor abundance (water vapor. The latitudinal and seasonal dependence of the decay of the northern summer water vapor maximum implies cross-equatorial transport of water to the southern hemisphere, while there is little or no corresponding transport during the decay of the southern hemisphere summer maximum. The latitude-longitude dependence of annually-averaged water vapor (corrected for topography) has a significant positive correlation with albedo and significant negative correlations with thermal inertia and surface pressure. Comparison of TES results with those retrieved from the Viking Orbiter Mars Atmospheric Water Detectors (MAWD) experiments shows some similar features, but also many significant differences. The southern hemisphere maximum observed by TES was not observed by MAWD and the large latitudinal gradient in annually-averaged water vapor observed by MAWD does not appear in the TES results.

  18. Morphological, thermal and physicochemical characteristics of small granules starch from Mirabilis jalapa L

    Energy Technology Data Exchange (ETDEWEB)

    Pumacahua-Ramos, Augusto [Department of Food Engineering, Universidad Peruana Unión, Juliaca (Peru); Paulista State University, IBILCE/UNESP, São Jose do Rio Preto, SP (Brazil); State University of Ponta Grossa–UEPG, Av. Carlos Cavalcanti, 4748, ZIP 84030-900 Ponta Grossa, PR (Brazil); Demiate, Ivo Mottin [State University of Ponta Grossa–UEPG, Av. Carlos Cavalcanti, 4748, ZIP 84030-900 Ponta Grossa, PR (Brazil); Schnitzler, Egon, E-mail: egons@uepg.br [State University of Ponta Grossa–UEPG, Av. Carlos Cavalcanti, 4748, ZIP 84030-900 Ponta Grossa, PR (Brazil); Bedin, Ana Cláudia [State University of Ponta Grossa–UEPG, Av. Carlos Cavalcanti, 4748, ZIP 84030-900 Ponta Grossa, PR (Brazil); Telis-Romero, Javier; Lopes-Filho, José Francisco [Paulista State University, IBILCE/UNESP, São Jose do Rio Preto, SP (Brazil)

    2015-02-20

    Highlights: • New source of small granules starch was studied. • DSC analysis allowed to determine the gelatinisation of starch from M. jalapa seeds. • Structural characteristics of granules were analysed by XRD and MEV techniques. • The rheological and thermal behaviour were analysed by RVA and TG–DTA. - Abstract: Some physicochemical and thermal properties of starch from Mirabilis jalapa L, seeds were evaluated. The starch was extracted after hulling and grinding the seeds and the flour obtained was suspended in 0.1% (m/v) NaOH solution for 12 h at 30 °C; it was then centrifuged, re-suspended, washed with deionised water and dried in an oven with circulating air at 40 °C for 12 h. The micro-images of starch granules were performed by using scanning electron (SEM) and non-contact atomic force microscopy (NC-AFM) techniques; X-ray diffraction and mid-infrared spectroscopy were both used to evaluate the relative crystallinity of the starch granules. Thermal analyses TG/DTG and DSC, were applied for the analysis of thermal behaviour of this starch and the cooking behaviour of its aqueous solution was studied by using a viscometer RVA. Thermogravimetry showed that once dehydrated, the starch was stable up to 292 °C after which two steps of decomposition occurred, which were attributed to decomposition and oxidation of organic matter, respectively. The gelatinisation temperature and enthalpy, as assessed by DSC analysis, were 82.1 °C and 5.67 J g{sup −1}, respectively. RVA analysis showed pasting temperature of 76.4 °C, with a low viscosity peak at 95 °C, low breakdown, and high tendency to retrograde during cooling. Microscopic results reveal that the starch granules had a spherical shape and 67.4% of them presented diameters smaller than 890 nm. The X-ray diffractogram showed a typical A-type pattern and a relative crystallinity of 34% with a FTIR of 1047/1022 cm{sup −1} and a ratio of 1.38.

  19. Thermal-Economic Modularization of Small, Organic Rankine Cycle Power Plants for Mid-Enthalpy Geothermal Fields

    Directory of Open Access Journals (Sweden)

    Yodha Y. Nusiaputra

    2014-07-01

    Full Text Available The costs of the surface infrastructure in mid-enthalpy geothermal power systems, especially in remote areas, could be reduced by using small, modular Organic Rankine Cycle (ORC power plants. Thermal-economic criteria have been devised to standardize ORC plant dimensions for such applications. We designed a modular ORC to utilize various wellhead temperatures (120–170 °C, mass flow rates and ambient temperatures (−10–40 °C. A control strategy was developed using steady-state optimization, in order to maximize net power production at off-design conditions. Optimum component sizes were determined using specific investment cost (SIC minimization and mean cashflow (MCF maximization for three different climate scenarios. Minimizing SIC did not yield significant benefits, but MCF proved to be a much better optimization function.

  20. Thermally activated delayed fluorescence as a cycling process between excited singlet and triplet states: application to the fullerenes.

    Science.gov (United States)

    Baleizão, Carlos; Berberan-Santos, Mário N

    2007-05-28

    In efficient thermally activated delayed fluorescence (TADF) the excited chromophore alternates randomly between the singlet and triplet manifolds a large number of times before emission occurs. In this work, the average number of cycles n is obtained and is shown to have a simple experimental meaning: n+1 is the intensification factor of the prompt fluorescence intensity, owing to the occurrence of TADF. A new method of data analysis for the determination of the quantum yield of triplet formation, combining steady-state and time-resolved data in a single plot, is also presented. Application of the theoretical results to the TADF of [70]fullerenes shows a general good agreement between different methods of fluorescence analysis and allows the determination of several photophysical parameters.

  1. Deposition Time and Thermal Cycles of Fabricating Thin-wall Steel Parts by Double Electrode GMAW Based Additive Manufacturing

    Directory of Open Access Journals (Sweden)

    Yang Dongqing

    2017-01-01

    Full Text Available The deposition time for fabricating the thin-wall part as well as the peak temperature of the substrate during the process was analyzed in the double electrode gas metal arc welding (DE-GMAW based additive manufacturing (AM. The total deposition time and the interlayer idle time of the manufacturing process decreased with the increasing of the bypass current under the same interlayer temperature and the same deposition rate. The thermal cycling curves illustrated that the peak temperature of the substrate was lower in the DE-GMAW base AM under the same conditions. When depositing the thin-wall parts, the DE-GMAW based AM can reduce the heat input to the substrate and improve the fabrication efficiency, compared with the GMAW based AM.

  2. Monitoring the Degradation Process of Inconel 600 and its Aluminide Coatings under Molten Sulfate Film with Thermal Cycles by Electrochemical Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Take, S.; Yoshinaga, S.; Yanagita, M.; Itoi, Y. [Oyama College, Tochigi (Japan)

    2016-12-15

    With a specially designed electrochemical cell, the changes in impedance behavior for Inconel 600 and aluminide diffusion coatings under molten sulfate film with thermal cycles (from 800 ℃ to 350 ℃) were monitored with electrochemical impedance measurements. It was found that corrosion resistance for both materials increased with lower temperatures. At the same time, the state of molten salt was also monitored successfully by measuring the changes in impedance at high frequency, which generally represents the resistance of molten salt itself. After two thermal cycles, both Inconel 600 and aluminide diffusion coatings showed excellent corrosion resistance. The results from SEM observation and EDS analysis correlated well with the results obtained by electrochemical impedance measurements. It is concluded that electrochemical impedance is very useful for monitoring the corrosion resistance of materials under molten salt film conditions even with thermal cycles.

  3. Study on Thermal Degradation Characteristics and Regression Rate Measurement of Paraffin-Based Fuel

    Directory of Open Access Journals (Sweden)

    Songqi Hu

    2015-09-01

    Full Text Available Paraffin fuel has been found to have a regression rate that is higher than conventional HTPB (hydroxyl-terminated polybutadiene fuel and, thus, presents itself as an ideal energy source for a hybrid rocket engine. The energy characteristics of paraffin-based fuel and HTPB fuel have been calculated by the method of minimum free energy. The thermal degradation characteristics were measured for paraffin, pretreated paraffin, HTPB and paraffin-based fuel in different working conditions by the using differential scanning calorimetry (DSC and a thermogravimetric analyzer (TGA. The regression rates of paraffin-based fuel and HTPB fuel were tested by a rectangular solid-gas hybrid engine. The research findings showed that: the specific impulse of paraffin-based fuel is almost the same as that of HTPB fuel; the decomposition temperature of pretreated paraffin is higher than that of the unprocessed paraffin, but lower than that of HTPB; with the increase of paraffin, the initial reaction exothermic peak of paraffin-based fuel is reached in advance, and the initial reaction heat release also increases; the regression rate of paraffin-based fuel is higher than the common HTPB fuel under the same conditions; with the increase of oxidizer mass flow rate, the regression rate of solid fuel increases accordingly for the same fuel formulation.

  4. Characteristics and Diurnal Cycle of GPM Rainfall Estimates over the Central Amazon Region

    Directory of Open Access Journals (Sweden)

    Rômulo Oliveira

    2016-06-01

    Full Text Available Studies that investigate and evaluate the quality, limitations and uncertainties of satellite rainfall estimates are fundamental to assure the correct and successful use of these products in applications, such as climate studies, hydrological modeling and natural hazard monitoring. Over regions of the globe that lack in situ observations, such studies are only possible through intensive field measurement campaigns, which provide a range of high quality ground measurements, e.g., CHUVA (Cloud processes of tHe main precipitation systems in Brazil: A contribUtion to cloud resolVing modeling and to the GlobAl Precipitation Measurement and GoAmazon (Observations and Modeling of the Green Ocean Amazon over the Brazilian Amazon during 2014/2015. This study aims to assess the characteristics of Global Precipitation Measurement (GPM satellite-based precipitation estimates in representing the diurnal cycle over the Brazilian Amazon. The Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (IMERG and the Goddard Profiling Algorithm—Version 2014 (GPROF2014 algorithms are evaluated against ground-based radar observations. Specifically, the S-band weather radar from the Amazon Protection National System (SIPAM, is first validated against the X-band CHUVA radar and then used as a reference to evaluate GPM precipitation. Results showed satisfactory agreement between S-band SIPAM radar and both IMERG and GPROF2014 algorithms. However, during the wet season, IMERG, which uses the GPROF2014 rainfall retrieval from the GPM Microwave Imager (GMI sensor, significantly overestimates the frequency of heavy rainfall volumes around 00:00–04:00 UTC and 15:00–18:00 UTC. This overestimation is particularly evident over the Negro, Solimões and Amazon rivers due to the poorly-calibrated algorithm over water surfaces. On the other hand, during the dry season, the IMERG product underestimates mean precipitation in comparison to the S-band SIPAM

  5. PEAR SHOOT SAWFLY (JANUS COMPRESSUS FABRICIUS – LIFE CYCLE AND BIOLOGICAL AND MORPHOLOGICAL CHARACTERISTIC

    Directory of Open Access Journals (Sweden)

    Tihomir Validžić

    2014-06-01

    Full Text Available The aim of the thesis was to investigate life cycle, biological and morphological characteristics of pear shoot sawfly (Janus compressus Fabricius, Hymenoptera Cephidae, furthermore to identify natural enemies in order to protect pear from this pest. The trial was conducted in the period of three years: 2010, 2011 and 2012 in pear orchards at five localities. Monitoring of adult sawfly was done by yellow sticky traps. Laboratory research was done at the Faculty of Agriculture, Department of Plant Protection, Section of Entomology and Nematology. In this study, pear shoot sawfly in Eastern Slavonia occurred in the period of four weeks, starting from the third decade of April with the peak population at the beginning of the May. Adults flight is the most intensive during warm and sunny days, when temperatures are above 14°C. Adult sawflies are characterized by elongated body and antennae, usually 7-12 mm long and sexual dimorphism is present. Pest is univoltine. Basic colour of adult sawfly is black. Antennae are moniliform and consist of 20 (male - 22 (female segments. Females have red or dark red colored abdomen, while males have yellow or orange one. Eggs are cylindrically shaped, 0.8-1.0 mm long. Female lays approximately 30 eggs. Embryonic development of pear shoot sawfly eggs lasts from 11 to 14 days. Larvae are 8-10 mm long, white or pale yellow. Larvae molt three times. Pear shoot sawfly larvae were parasitized by insects from Hymenoptera order, from five identified and one unidentified genera. Level of parasitism by genera is as follows: Eurytoma sp. (Hymenoptera: Eurytomidae – 9.83%, Tetrastichus sp. (Hymenoptera: Eulophidae – 2.01%, Eupelmus sp. (Hymenoptera: Eupelmidae – 1.66%, Pteromalus sp. (Hymenoptera: Pteromalidae – 0.55%, Ichneumonida sp. (Hymenoptera: Pimplinae – 0.35% and unidentified genera – 0.62%. Plant parasitic species Metopoplax origani (Hemiptera: Lygaeidae was found in 1.80% of analyzed shoots. Larvae were

  6. Energy losses in thermally cycled optical fibers constrained in small bend radii

    Energy Technology Data Exchange (ETDEWEB)

    Guild, Eric; Morelli, Gregg

    2012-09-23

    High energy laser pulses were fired into a 365μm diameter fiber optic cable constrained in small radii of curvature bends, resulting in a catastrophic failure. Q-switched laser pulses from a flashlamp pumped, Nd:YAG laser were injected into the cables, and the spatial intensity profile at the exit face of the fiber was observed using an infrared camera. The transmission of the radiation through the tight radii resulted in an asymmetric intensity profile with one half of the fiber core having a higher peak-to-average energy distribution. Prior to testing, the cables were thermally conditioned while constrained in the small radii of curvature bends. Single-bend, double-bend, and U-shaped eometries were tested to characterize various cable routing scenarios.

  7. Impacts of weld residual stresses and fatigue crack growth threshold on crack arrest under high-cycle thermal fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Taheri, Said, E-mail: Said.taheri@edf.fr [EDF-LAB, IMSIA, 7 Boulevard Gaspard Monge, 91120 Palaiseau Cedex (France); Julan, Emricka [EDF-LAB, AMA, 7 Boulevard Gaspard Monge, 91120 Palaiseau Cedex (France); Tran, Xuan-Van [EDF Energy R& D UK Centre/School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, Manchester M13 9PL (United Kingdom); Robert, Nicolas [EDF-DPN, UNIE, Strategic Center, Saint Denis (France)

    2017-01-15

    Highlights: • For crack growth analysis, weld residual stress field must be considered through its SIF in presence of a crack. • Presence of cracks of same depth proves their arrest, where equal depth is because mean stress acts only on crack opening. • Not considering amplitudes under a fatigue crack growth threshold (FCGT) does not compensate the lack of FGCT in Paris law. • Propagation rates are close for axisymmetric and circumferential semi-elliptical cracks. - Abstract: High cycle thermal crazing has been observed in some residual heat removal (RHR) systems made of 304 stainless steel in PWR nuclear plants. This paper deals with two types of analyses including logical argumentation and simulation. Crack arrest in networks is demonstrated due to the presence of two cracks of the same depth in the network. This identical depth may be proved assuming that mean stress acts only on crack opening and that cracks are fully open during the load cycle before arrest. Weld residual stresses (WRS) are obtained by an axisymmetric simulation of welding on a tube with a chamfer. Axisymmetric and 3D parametric studies of crack growth on: representative sequences for variable amplitude thermal loading, fatigue crack growth threshold (FCGT), permanent mean stress, cyclic counting methods and WRS, are performed with Code-Aster software using XFEM methodology. The following results are obtained on crack depth versus time: the effect of WRS on crack growth cannot be determined by the initial WRS field in absence of crack, but by the associated stress intensity factor. Moreover the relation between crack arrest depth and WRS is analyzed. In the absence of FCGT Paris’s law may give a significant over-estimation of crack depth even if amplitudes of loading smaller than FCGT have not been considered. Appropriate depth versus time may be obtained using different values of FCGT, but axisymmetric simulations do not really show a possibility of arrest for shallow cracks in

  8. University of Minnesota aquifer thermal energy storage (ATES) project report on the third long-term cycle

    Energy Technology Data Exchange (ETDEWEB)

    Hoyer, M.C.; Hallgren, J.P.; Uebel, M.H.; Delin, G.N.; Eisenreich, S.J.; Sterling, R.L.

    1994-12-01

    The University of Minnesota aquifer thermal energy storage (ATES) system has been operated as a field test facility (FTF) since 1982. The objectives were to design, construct, and operate the facility to study the feasibility of high-temperature ATES in a confined aquifer. Four short-term and two long-term cycles were previously conducted, which provided a greatly increased understanding of the efficiency and geochemical effects of high-temperature aquifer thermal energy storage. The third long-term cycle (LT3) was conducted to operate the ATES system in conjunction with a real heating load and to further study the geochemical impact that heated water storage had on the aquifer. For LT3, the source and storage wells were modified so that only the most permeable portion, the Ironton-Galesville part, of the Franconia-Ironton-Galesville aquifer was used for storage. This was expected to improve storage efficiency by reducing the surface area of the heated volume and simplify analysis of water chemistry results by reducing the number of aquifer-related variables which need to be considered. During LT3, a total volume of 63.2 {times} 10{sup 3} m {sup 3} of water was injected at a rate of 54.95 m{sup 3}/hr into the storage well at a mean temperature of 104.7{degrees}C. Tie-in to the reheat system of the nearby Animal Sciences Veterinary Medicine (ASVM) building was completed after injection was completed. Approximately 66 percent (4.13 GWh) of the energy added to the aquifer was recovered. Approximately 15 percent (0.64 GWh) of the usable (10 building. Operations during heat recovery with the ASVM building`s reheat system were trouble-free. Integration into more of the ASVM (or other) building`s mechanical systems would have resulted in significantly increasing the proportion of energy used during heat recovery.

  9. Low Temperature Creep of Hot-Extruded Near-Stoichiometric NiTi Shape Memory Alloy. Part 2; Effect of Thermal Cycling

    Science.gov (United States)

    Raj, S. V.; Noebe, R. D.

    2013-01-01

    This paper is the first report on the effect prior low temperature creep on the thermal cycling behavior of NiTi. The isothermal low temperature creep behavior of near-stoichiometric NiTi between 300 and 473 K was discussed in Part I. The effect of temperature cycling on its creep behavior is reported in the present paper (Part II). Temperature cycling tests were conducted between either 300 or 373 K and 473 K under a constant applied stress of either 250 or 350 MPa with hold times lasting at each temperature varying between 300 and 700 h. Each specimen was pre-crept either at 300 or at 473 K for several months under an identical applied stress as that used in the subsequent thermal cycling tests. Irrespective of the initial pre-crept microstructures, the specimens exhibited a considerable increase in strain with each thermal cycle so that the total strain continued to build-up to 15 to 20 percent after only 5 cycles. Creep strains were immeasurably small during the hold periods. It is demonstrated that the strains in the austenite and martensite are linearly correlated. Interestingly, the differential irrecoverable strain, in the material measured in either phase decreases with increasing number of cycles, similar to the well-known Manson-Coffin relation in low cycle fatigue. Both phases are shown to undergo strain hardening due to the development of residual stresses. Plots of true creep rate against absolute temperature showed distinct peaks and valleys during the cool-down and heat-up portions of the thermal cycles, respectively. Transformation temperatures determined from the creep data revealed that the austenitic start and finish temperatures were more sensitive to the pre-crept martensitic phase than to the pre-crept austenitic phase. The results are discussed in terms of a phenomenological model, where it is suggested that thermal cycling between the austenitic and martensitic phase temperatures or vice versa results in the deformation of the austenite and

  10. Airflow characteristics and pollution distribution around a thermal manikin - Impact of specific personal and indoor environmental factors

    DEFF Research Database (Denmark)

    Licina, Dusan; Tham, Kwok Wai; Melikov, Arsen Krikor

    2016-01-01

    This study presents a summary of experimental measurements on the airflow characteristics and pollution distribution around a non-breathing thermal manikin. The two objectives are: (1) to examine the extent to which personal (body posture, clothing insulation, table positioning) and environmental......, and ventilation flow considerably affected airflow characteristics and pollution distribution around the thermal manikin. Under the specific set of conditions studied, the most favorable airflow patterns in preventing the feet pollution from reaching the breathing zone was transverse flow from the front...

  11. Computer code system for the R and D of nuclear fuel cycle with fast reactor. 2. Development and application of analytical evaluation system for thermal striping phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Muramatsu, Toshiharu [Japan Nuclear Cycle Development Inst., Oarai, Ibaraki (Japan). Oarai Engineering Center

    2001-09-01

    Fluid-structure thermal interaction phenomena characterized by stationary random temperature fluctuations, namely thermal striping are observed in the downstream region such as a T-junction piping system of liquid metal fast reactors (LMFRs). Therefore, the piping wall located in the downstream region must be protected against the stationary random thermal process, which might induce high-cycle fatigue. This paper describes the evaluation system based on numerical simulation methods consisting of three thermohydraulics computer programs AQUA, DINUS-3 and THEMIS and of three thermomechanical computer programs BEMSET, FINAS and CANIS, for the thermal striping developed at Japan Nuclear Cycle Development Institute (JNC). Verification results for each computer code and the system are also introduced based on out-of-pile experimental data using water and sodium as working fluids. (author)

  12. Menstrual cycle characteristics in fertile women from Greenland, Poland and Ukraine exposed to perfluorinated chemicals: a cross-sectional study.

    Science.gov (United States)

    Lyngsø, J; Ramlau-Hansen, C H; Høyer, B B; Støvring, H; Bonde, J P; Jönsson, B A G; Lindh, C H; Pedersen, H S; Ludwicki, J K; Zviezdai, V; Toft, G

    2014-02-01

    Does perfluorooctane sulfonate (PFOS) and perfluorooctanate (PFOA) exposure disrupt the menstrual cyclicity? The female reproductive system may be sensitive to PFOA exposure, with longer menstrual cycle length at higher exposure. PFOS and PFOA are persistent man-made chemicals. Experimental animal studies suggest they are reproductive toxicants but epidemiological findings are inconsistent. A cross-sectional study including 1623 pregnant women from the INUENDO cohort enrolled during antenatal care visits between June 2002 and May 2004 in Greenland, Poland and Ukraine. Information on menstrual cycle characteristics was obtained by questionnaires together with a blood sample from each pregnant woman. Serum concentrations of PFOS and PFOA were measured by liquid chromatography tandem mass spectrometry. Multiple imputations were performed to account for missing data. The association between PFOS/PFOA and menstrual cycle length (short cycle: ≤24 days, long cycle: ≥32 days) and irregularities (≥7 days in difference between cycles) was analyzed using logistic regression with tertiles of exposure. Estimates are given as adjusted odds ratios (ORs) with 95% confidence intervals (CIs). Higher exposure levels of PFOA were associated with longer menstrual cycles in pooled estimates of all three countries. Compared with women in the lowest exposure tertile, the adjusted OR of long cycles was 1.8 (95% CI: 1.0; 3.3) among women in the highest tertile of PFOA exposure. No significant associations were observed between PFOS exposure and menstrual cycle characteristics. However, we observed a tendency toward more irregular cycles with higher exposure to PFOS [OR 1.7 (95% CI: 0.8; 3.5)]. The overall response rate was 45.3% with considerable variation between countries (91.3% in Greenland, 69.1% in Poland and 26.3% in Ukraine). Possible limitations in our study include varying participation rates across countries; a selected study group overrepresenting the most fertile part of

  13. Thermal recycling of polystyrene and polystyrene-butadiene dissolved in a light cycle oil

    Energy Technology Data Exchange (ETDEWEB)

    Arandes, Jose M.; Erena, Javier; Olazar, Martin; Bilbao, Javier [Departamento de Ingenieria Quimica, Universidad del Pais Vasco, Apartado 644, 48080 Bilbao (Spain); Azkoiti, Miren J. [Departamento de Ingenieria Quimica y del Medio Ambiente, Universidad del Pais Vasco, Plaza de la Casilla 3, 48012 Bilbao (Spain)

    2003-12-01

    A study has been made of the cracking on a mesoporous silica of polystyrene (PS) and polystyrene-butadiene (PS-BD) dissolved in a light cycle oil (LCO) from a product stream of a commercial fluid catalytic cracking (FCC) unit. This study has been carried out in a reactor of short contact time (3 s) in the 723-823 K range. This strategy for simultaneous valorization of plastics and solvent avoids the technological problems inherent to the treatment of solid postconsumer-plastics and the limitation to heat transfer in the process of pyrolysis. The cracking of plastics has a synergistic effect on the conversion of LCO, as it contributes to increasing the yield of gasoline (C{sub 5}-C{sub 12}). The cracking of the PS/LCO blend produces high yields of styrene, whereas the cracking of the PS-BD/LCO blend produces a stream of products with petrochemical interest.

  14. Life cycle assessment of hemp cultivation and use of hemp-based thermal insulator materials in buildings.

    Science.gov (United States)

    Zampori, Luca; Dotelli, Giovanni; Vernelli, Valeria

    2013-07-02

    The aim of this research is to assess the sustainability of a natural fiber, such as hemp (Cannabis sativa), and its use as thermal insulator for building applications. The sustainability of hemp was quantified by life cycle assessment (LCA) and particular attention was given to the amount of CO2eq of the whole process, and the indicator greenhouse gas protocol (GGP) was selected to quantify CO2eq emissions. In this study also CO2 uptake of hemp was considered. Two different allocation procedures (i.e., mass and economic) were adopted. Other indicators, such as Cumulative Energy Demand (CED) and EcoIndicator99 H were calculated. The production of 1 ha yielded 15 ton of hemp, whose global warming potential (GWP100) was equal to about -26.01 ton CO2eq: the amount allocated to the technical fiber (20% of the total amount of hemp biomass) was -5.52 ton CO2eq when mass allocation was used, and -5.54 ton CO2eq when economic allocation was applied. The sustainability for building applications was quantified by considering an insulation panel made by hemp fiber (85%) and polyester fiber (15%) in 1 m(2) of wall having a thermal transmittance (U) equal to 0.2 W/m(2)_K. The environmental performances of the hemp-based panel were compared to those of a rockwool-based one.

  15. The effect of thermal cycling to 1100 degree C on the alpha (Mo) phase in directionally solidified gamma/gamma prime-alpha alloys

    Science.gov (United States)

    Harf, F. H.

    1981-01-01

    In gamma/gamma prime - alpha eutectic alloys (Ni-Mo-Al), the resistance of the alpha phase to morphological changes during thermal cycling was found to be dependent on the structure formed during directional solidification. Fine, smooth alpha fibers survived up to 1000 five minute cycles to 1100 C with minor microstructural contour changes, while coarser and irregularly shaped alpha fibers tended to spheroidize. A mechanism to explain this phenomenon is proposed. It is suggested that on heating to 1100 C, the alpha phase is likely to undergo morphological changes, until differential thermal expansion creates a stress free interface between the alpha phase and the gamma/gamma prime matrix.

  16. Impact of Total Ionizing Dose Radiation Testing and Long-Term Thermal Cycling on the Operation of CMF20120D Silicon Carbide Power MOSFET

    Science.gov (United States)

    Patterson, Richard L.; Scheidegger, Robert J.; Lauenstein, Jean-Marie; Casey, Megan; Scheick, Leif; Hammoud, Ahmad

    2013-01-01

    Power systems designed for use in NASA space missions are required to work reliably under harsh conditions including radiation, thermal cycling, and extreme temperature exposures. Silicon carbide devices show great promise for use in future power electronics systems, but information pertaining to performance of the devices in the space environment is very scarce. A silicon carbide N-channel enhancement-mode power MOSFET called the CMF20120 is of interest for use in space environments. Samples of the device were exposed to radiation followed by long-term thermal cycling to address their reliability for use in space applications. The results of the experimental work are presentd and discussed.

  17. Does thermal variability experienced at the egg stage influence life history traits across life cycle stages in a small invertebrate?

    Directory of Open Access Journals (Sweden)

    Kun Xing

    Full Text Available Although effects of thermal stability on eggs have often been considered in vertebrates, there is little data thermal stability in insect eggs even though these eggs are often exposed in nature to widely fluctuating ambient conditions. The modularity of development in invertebrates might lead to compensation across life cycle stages but this remains to be tested particularly within the context of realistic temperature fluctuations encountered in nature. We simulated natural temperate fluctuations on eggs of the worldwide cruciferous insect pest, the diamondback moth (DBM, Plutella xylostella (L., while maintaining the same mean temperature (25°C±0°C, 25±4°C, 25±6°C, 25±8°C, 25±10°C, 25±12°C and assessed egg development, survival and life history traits across developmental stages. Moderate fluctuations (25±4°C, 25±6°C did not influence performance compared to the constant temperature treatment, and none of the treatments influenced egg survival. However the wide fluctuating temperatures (25±10°C, 25±12°C slowed development time and led to an increase in pre-pupal mass, although these changes did not translate into any effects on longevity or fecundity at the adult stage. These findings indicate that environmental effects can extend across developmental stages despite the modularity of moth development but also highlight that there are few fitness consequences of the most variable thermal conditions likely to be experienced by Plutella xylostella.

  18. Model of the Evolution of Deformation Defects and Irreversible Strain at Thermal Cycling of Stressed TiNi Alloy Specimen

    Directory of Open Access Journals (Sweden)

    Volkov Aleksandr E.

    2015-01-01

    Full Text Available This microstructural model deals with simulation both of the reversible and irreversible deformation of a shape memory alloy (SMA. The martensitic transformation and the irreversible deformation due to the plastic accommodation of martensite are considered on the microscopic level. The irreversible deformation is described from the standpoint of the plastic flow theory. Isotropic hardening and kinematic hardening are taken into account and are related to the densities of scattered and oriented deformation defects. It is supposed that the phase transformation and the micro plastic deformation are caused by the generalized thermodynamic forces, which are the derivatives of the Gibbs’ potential of the two-phase body. In terms of these forces conditions for the phase transformation and for the micro plastic deformation on the micro level are formulated. The macro deformation of the representative volume of the polycrystal is calculated by averaging of the micro strains related to the evolution of the martensite Bain’s variants in each grain comprising this volume. The proposed model allowed simulating the evolution of the reversible and of the irreversible strains of a stressed SMA specimen under thermal cycles. The results show a good qualitative agreement with available experimental data. Specifically, it is shown that the model can describe a rather big irreversible strain in the first thermocycle and its fast decrease with the number of cycles.

  19. Thermal tests of a multi-tubular reactor for hydrogen production by using mixed ferrites thermochemical cycle

    Science.gov (United States)

    Gonzalez-Pardo, Aurelio; Denk, Thorsten; Vidal, Alfonso

    2017-06-01

    The SolH2 project is an INNPACTO initiative of the Spanish Ministry of Economy and Competitiveness, with the main goal to demonstrate the technological feasibility of solar thermochemical water splitting cycles as one of the most promising options to produce H2 from renewable sources in an emission-free way. A multi-tubular solar reactor was designed and build to evaluate a ferrite thermochemical cycle. At the end of this project, the ownership of this plant was transferred to CIEMAT. This paper reviews some additional tests with this pilot plant performed in the Plataforma Solar de Almería with the main goal to assess the thermal behavior of the reactor, evaluating the evolution of the temperatures inside the cavity and the relation between supplied power and reached temperatures. Previous experience with alumina tubes showed that they are very sensitive to temperature and flux gradients, what leads to elaborate an aiming strategy for the heliostat field to achieve a uniform distribution of the radiation inside the cavity. Additionally, the passing of clouds is a phenomenon that importantly affects all the CSP facilities by reducing their efficiency. The behavior of the reactor under these conditions has been studied.

  20. Thermal Capacitive Electrochemical Cycle on Carbon-Based Supercapacitor for Converting Low-grade Heat to Electricity

    Directory of Open Access Journals (Sweden)

    Xun Wang

    2017-11-01

    Full Text Available It is a great challenge to efficiently convert low-grade heat (<100°C to electricity. Currently available heat-to-current converters, such as thermoelectric generators, operating in a low-grade heat regime reach efficiencies no higher than a few percent (<3%. Herein, we illustrated a thermal capacitive electrochemical cycle (TCEC using electrochemical cell, where the connection to the hot or cold reservoirs alternates in a cyclic charging–heating–discharging–cooling mode to convert heat into electricity, which performs as an electrochemical heat engine. TCEC technology is a cost-effective method for exploiting the temperature-dependent electrostatic potential in an electric double layer (EDL at carbon electrode/electrolyte interfaces; it produces net electricity by altering the EDL thickness via heating and cooling. In this paper, TCEC on supercapacitor was confirmed on commercial supercapacitor, which showed a poor conversion efficiency. To improve the performance, we redesigned the cell by employing the pouch cell setup with activated carbon as electrode materials and homemade temperature controlling system, which boosted the efficiency from 0.5% of commercial supercapacitor to 3.05% when cycling between 10 and 65°C. A higher efficiency of 3.95% could be reached by using microwaved exfoliated graphene nanosheets (MEG and nitric acid-treated MEG, which could help in decreasing the energy loss caused by charge leakage.

  1. Effect of tooth brushing and thermal cycling on a surface change of ceromers finished with different methods.

    Science.gov (United States)

    Cho, L-R; Yi, Y-J; Heo, S-J

    2002-09-01

    This in vitro study evaluated the effect of tooth brushing and thermal cycling on the surface lustre and surface roughness of three ceromer systems treated with different surface finishing methods. The ceromers studied were: (1). Artglass, (2). Targis, (3). Sculpture and (4). the control group, Z 100. Half of the Targis and Sculpture groups were polished and the rest were coated with staining and glazing solution, respectively. All specimens were subjected to thermocycling 10000 times. Tooth brushing abrasion tests were performed in a customized tooth-brushing machine with 500 g weight applied on a back-and-forth cycle for 20000 repetitions. The lustre determined by measuring the light reflection area and the average roughness was compared between groups and between pre- and post-test values. All materials showed a lower lustre and rougher surface after thermocycling and tooth brushing (P ceromer specimens, except glazed Sculpture, showed a higher lustre and similar roughness to the control group. The post-brushing results revealed that glazed Sculpture presented discretely fallen out glaze coatings and had maximum change. However, stained Targis showed minimum change (P < 0.05) and polished Targis presented more changes than that of the staining treatment. It is therefore concluded that the glaze coatings for Sculpture don't exhibit long-term durability, while stain coatings for Targis acted like a protective layer.

  2. Investigations on Structural Characteristics, Thermal Stability, and Hygroscopicity of Sisal Fibers at Elevated Temperatures

    Science.gov (United States)

    Saikia, Dip

    2008-12-01

    An effort has been made to study the thermophysical properties of sisal plant fiber available in North-East India in the temperature range from 310 K to 760 K. The effect of heat on the structural characteristics of the fiber using X-ray diffraction and the chemical behavior by the infrared (IR) technique has been examined. Thermodynamic studies of the fiber have been carried out using thermogravimetric (TG), derivative TG (DTG), and differential scanning calorimetric methods. The hygroscopic properties of the fiber have been investigated in the temperature range from 310 K to 430 K at different relative air humidities using an ordinary gravimetric analysis. The interplanar spacings of the sample heated to 370 K remained same with respect to their normal values, but the degree of crystallinity and crystallite sizes increased slightly. The degree of crystallinity of the sample heated to 450 K is decreased by 10.32 % from its normal value, and the corresponding interplanar spacings and crystallite sizes are decreased by a small amount. A sample heated to 530 K shows transformation of the fiber’s crystalline structure to an amorphous state. The fiber shows thermal stability up to 500 K and follows two different closely related thermal decomposition processes in the temperature range of approximately 500 K to 630 K. Tests performed in oxygen can lead to combustion of the fibers in the temperature range of approximately 710 K to 720 K. The IR study of the sample heated at temperatures from 370 K to 600 K provides meaningful data to ascertain decomposition of the native structure of the fibers. The hygroscopicity of the fiber under heated conditions is less with respect to the value under ambient conditions. The saturation limit of moisture absorption of the fiber per gram varies and depends on the source as well as pretreatment of the sample.

  3. Evaluation of deep moonquake source parameters: Implication for fault characteristics and thermal state

    Science.gov (United States)

    Kawamura, Taichi; Lognonné, Philippe; Nishikawa, Yasuhiro; Tanaka, Satoshi

    2017-07-01

    While deep moonquakes are seismic events commonly observed on the Moon, their source mechanism is still unexplained. The two main issues are poorly constrained source parameters and incompatibilities between the thermal profiles suggested by many studies and the apparent need for brittle properties at these depths. In this study, we reinvestigated the deep moonquake data to reestimate its source parameters and uncover the characteristics of deep moonquake faults that differ from those on Earth. We first improve the estimation of source parameters through spectral analysis using "new" broadband seismic records made by combining those of the Apollo long- and short-period seismometers. We use the broader frequency band of the combined spectra to estimate corner frequencies and DC values of spectra, which are important parameters to constrain the source parameters. We further use the spectral features to estimate seismic moments and stress drops for more than 100 deep moonquake events from three different source regions. This study revealed that deep moonquake faults are extremely smooth compared to terrestrial faults. Second, we reevaluate the brittle-ductile transition temperature that is consistent with the obtained source parameters. We show that the source parameters imply that the tidal stress is the main source of the stress glut causing deep moonquakes and the large strain rate from tides makes the brittle-ductile transition temperature higher. Higher transition temperatures open a new possibility to construct a thermal model that is consistent with deep moonquake occurrence and pressure condition and thereby improve our understandings of the deep moonquake source mechanism.

  4. Four-wall turbine airfoil with thermal strain control for reduced cycle fatigue

    Science.gov (United States)

    Cambell, Christian X

    2013-09-17

    A turbine airfoil (20B) with a thermal expansion control mechanism that increases the airfoil camber (60, 61) under operational heating. The airfoil has four-wall geometry, including pressure side outer and inner walls (26, 28B), and suction side outer and inner walls (32, 34B). It has near-wall cooling channels (31F, 31A, 33F, 33A) between the outer and inner walls. A cooling fluid flow pattern (50C, 50W, 50H) in the airfoil causes the pressure side inner wall (28B) to increase in curvature under operational heating. The pressure side inner wall (28B) is thicker than walls (26, 34B) that oppose it in camber deformation, so it dominates them in collaboration with the suction side outer wall (32), and the airfoil camber increases. This reduces and relocates a maximum stress area (47) from the suction side outer wall (32) to the suction side inner wall (34B, 72) and the pressure side outer wall (26).

  5. Characteristics of estrous cycles in gilts treated with gonadotropins after estrus or treatment with a progestogen.

    Science.gov (United States)

    Estienne, Mark J; Crawford, Russell J

    2015-03-01

    A combination of eCG (400 IU) and hCG (200 IU) (P.G. 600; Merck Animal Health, Summit, NJ, USA) stimulates puberty in gilts, but variation in the estrual response exists among farms. We hypothesized that some of the variability is a consequence of gilts that have commenced cycling being inadvertently treated. The objective of experiment 1 was to determine the effect of intramuscular (im) P.G. 600 on estrous cycles in sexually mature gilts. Gilts in treatment 1 (n = 16) received P.G. 600 at the onset of daily boar exposure. Gilts in treatments 2 to 5 (n = 16 per treatment) were allowed to express a natural first estrus and were then treated with P.G. 600 during the first estrous cycle as follows: treatment 2 at Day 6, treatment 3 at Day 12, and treatment 4 at Day 18 of the estrous cycle. Treatment 5 gilts received no P.G. 600. The proportion of gilts displaying a normal estrous cycle (18-24 days) was greater (P gilts displayed an increased interestrus interval that averaged 32.5 days. Concentrations of progesterone remained elevated 20 days after the onset of first estrus in treatment 3 gilts, which supports the concept that P.G. 600 administered at Day 12 of the estrous cycle induced follicular growth, ovulation, and formation of CL that functioned for approximately 15 days, increasing the length of the estrous cycle. It is common for swine producers to have groups of replacement gilts that include both cycling and prepubertal animals, or individuals, the cycling status of which is unknown. The objective of experiment 2 was to evaluate a system using a combination of a progestogen (Matrix; Merck Animal Health) and P.G. 600 to synchronize estrus in replacement gilts. Crossbred gilts, assumed to be a mix of cycling and prepubertal females, were allocated to one of four treatments (n = 12 per treatment): treatment 1, Matrix (15 mg/day) fed for 14 days and im P.G. 600 24 hours after the last feeding of Matrix; treatment 2, Matrix for 7 days and P.G. 600

  6. Taking the Time Characteristic into Account of Life Cycle Assessment: Method and Application for Buildings

    Directory of Open Access Journals (Sweden)

    Yurong Zhang

    2017-05-01

    Full Text Available Life cycle assessment (LCA involves many temporal issues. It is necessary to make a clear distinction between long-term impacts and short-term impacts, especially for those structures with long service life, such as buildings. With their long service life of 50 years, a great deal of maintenance and repairs could be conducted, causing a respective environmental impact. In this paper we explored a monetization method to convert the life cycle environmental impact into a life cycle environmental cost to address the temporal issues involved in LCA by discounting. This method can facilitate decision-making when tradeoffs between current and future environmental impacts exist. Moreover, this method can be used as an effective supplement to life cycle cost and provide decision support for making trade-off between cost and environmental impact. Finally, a building located in Xiamen City, China was selected as a case study and analyzed by the proposal LCA method. The results indicated that carbon cost in the operational stage is the maximum, building material production and transportation stages are ranked second, and the amount in the demolition stage is negligible, compared with the other three stages. Additionally, with the increase of the discount rate, the carbon cost in different life cycle stages will decrease, the percentage of the carbon cost in the operational stage will gradually decrease, but the percentage of the carbon cost in building material production and transportation stages will gradually increase.

  7. Research on thermal characteristics of heat pipes for led lightning devices

    Directory of Open Access Journals (Sweden)

    Lozovoi M. A.

    2014-12-01

    Full Text Available New energy-saving technologies for lighting is a promising trend in lighting technology. To this end, during the recent decade, have been actively developed and implemented lighting units based on LED modules. Reliability of such devices is largely dependent on the ensuring of cooling of the LEDs. Heat pipes are being used with ever increasing frequency for increasing an efficiency of cooling of powerful LEDs within a lightening device. Results of experimental modeling of thermal characteristics of two aluminum heat pipes with grooved capillary structure and ammonia used as a heat transfer agent, designed for application as a heat transfer elements in designs of powerful LED lightening device with forced air cooling are presented in this paper. It is shown that for the heat flux range of 50 to 100 W and for incident flow speed in the range of 0.8 to 2.1 m/s the temperature in the heating zone of the heat pipe falls into the range of 31.0 to 52.5 °C. In this case the temperature difference along the heat pipe is between 0.9…1.7 °C, when a minimal value of the fed heat flux is 50 W, and 1.7…3.1°C, when a maximum value of the heat flux is 100 W. The value of heat transfer resistance of the heat pipes was in the range of 0.012 to 0.044 °C/W. The key factors influencing the thermal characteristics of the heat pipes are: the value of the fed heat flux, the speed of cooling air flux, heat pipe inclination angle with respect to the horizon. By using five such heat pipes within the powerful LED lightning device it is possible to achieve an elimination of the total heat flux from LED modules up to 500 W. At an efficiency factor of LEDs of about 75% this is equivalent to intake power 665 W. Taking into account that luminous efficiency of modern LEDs is about 10 times as high as those of incandescent lamps, proposed lightning device will produce a luminous flux which is equivalent to the luminous flux of a lightening device with incandescent lamps

  8. Menstrual cycle characteristics and reproductive hormone levels in women exposed to atrazine in drinking water.

    Science.gov (United States)

    Cragin, Lori A; Kesner, James S; Bachand, Annette M; Barr, Dana Boyd; Meadows, Juliana W; Krieg, Edward F; Reif, John S

    2011-11-01

    Atrazine is the most commonly used herbicide in the U.S. and a wide-spread groundwater contaminant. Epidemiologic and laboratory evidence exists that atrazine disrupts reproductive health and hormone secretion. We examined the relationship between exposure to atrazine in drinking water and menstrual cycle function including reproductive hormone levels. Women 18-40 years old residing in agricultural communities where atrazine is used extensively (Illinois) and sparingly (Vermont) answered a questionnaire (n=102), maintained menstrual cycle diaries (n=67), and provided daily urine samples for analyses of luteinizing hormone (LH), and estradiol and progesterone metabolites (n=35). Markers of exposures included state of residence, atrazine and chlorotriazine concentrations in tap water, municipal water and urine, and estimated dose from water consumption. Women who lived in Illinois were more likely to report menstrual cycle length irregularity (odds ratio (OR)=4.69; 95% confidence interval (CI): 1.58-13.95) and more than 6 weeks between periods (OR=6.16; 95% CI: 1.29-29.38) than those who lived in Vermont. Consumption of >2 cups of unfiltered Illinois water daily was associated with increased risk of irregular periods (OR=5.73; 95% CI: 1.58-20.77). Estimated "dose" of atrazine and chlorotriazine from tap water was inversely related to mean mid-luteal estradiol metabolite. Atrazine "dose" from municipal concentrations was directly related to follicular phase length and inversely related to mean mid-luteal progesterone metabolite levels. We present preliminary evidence that atrazine exposure, at levels below the US EPA MCL, is associated with increased menstrual cycle irregularity, longer follicular phases, and decreased levels of menstrual cycle endocrine biomarkers of infertile ovulatory cycles. Copyright © 2011 Elsevier Inc. All rights reserved.

  9. Thermal characteristics and corrosion behaviour of Mg–xZn alloys ...

    Indian Academy of Sciences (India)

    The thermal parameters of Mg–Zn cast alloys with 0.5–9 wt% Zn were evaluated by using computer aided cooling curve thermal analysis (CA–CCTA), whereas the corrosion behaviour was investigated by potentiodynamic polarization and immersion tests. Thermal analysis results revealed that the dendrite coherency ...

  10. Airflow characteristics and pollution distribution around a thermal manikin - Impact of specific personal and indoor environmental factors

    DEFF Research Database (Denmark)

    Licina, Dusan; Tham, Kwok Wai; Melikov, Arsen Krikor

    2016-01-01

    This study presents a summary of experimental measurements on the airflow characteristics and pollution distribution around a non-breathing thermal manikin. The two objectives are: (1) to examine the extent to which personal (body posture, clothing insulation, table positioning) and environmental...

  11. Performance Degradation of Thermal Parameters during Cycle Ageing of High Energy Density Ni-Mn-Co based Lithium-Ion Battery Cells

    DEFF Research Database (Denmark)

    Stanciu, Tiberiu; Stroe, Daniel Loan; Swierczynski, Maciej Jozef

    2016-01-01

    The accelerated demand for electrifying the transportation sector, coupled with the continuous improvement of rechargeable batteries’ characteristics, have made modern high-energy Lithium-ion (Li-ion) batteries the standard choice for hybrid and electric vehicles (EVs). Consequently, Li......-ion batteries’ electrochemical and thermal characteristics are very important topics, putting them at the forefront of the research. Along with the electrical performance of Li-ion battery cells, their thermal behavior needs to be accurately predicted during operation and over the lifespan of the application...... as well, since the thermal management of the battery is crucial for the safety of the EV driver. Moreover, the thermal management system can significantly lower the degradation rate of the battery pack and thus reduce costs. In this paper, the thermal characterization of a commercially available Nickel...

  12. Loss Prediction and Thermal Analysis of Surface-Mounted Brushless AC PM Machines for Electric Vehicle Application Considering Driving Duty Cycle

    Directory of Open Access Journals (Sweden)

    Tianxun Chen

    2016-01-01

    Full Text Available This paper presents a computationally efficient loss prediction procedure and thermal analysis of surface-mounted brushless AC permanent magnet (PM machine considering the UDDS driving duty cycle by using a lumped parameters’ thermal model. The accurate prediction of loss and its variation with load are essential for thermal analysis. Employing finite element analysis (FEA to determine loss at every load point would be computationally intensive. Here, the finite element analysis and/or experiment based computationally efficient winding copper and iron loss and permanent magnet (PM power loss models are employed to calculate the electromagnetic loss at every operation point, respectively. Then, the lumped parameter thermal method is used to analyse the thermal behaviour of the driving PM machine. Experiments have been carried out to measure the temperature distribution in a motor prototype. The calculation and experiment results are compared and discussed.

  13. Fatigue failure kinetics and structural changes in lead-free interconnects due to mechanical and thermal cycling

    Science.gov (United States)

    Fiedler, Brent Alan

    Environmental and human health concerns drove European parliament to mandate the Reduction of Hazardous Substances (RoHS) for electronics. This was enacted in July 2006 and has practically eliminated lead in solder interconnects. There is concern in the electronics packaging community because modern lead-free solder is rich in tin. Presently, near-eutectic tin-silver-copper solders are favored by industry. These solders are stiffer than the lead-tin near-eutectic alloys, have a higher melting temperature, fewer slip systems, and form intermetallic compounds (IMC) with Cu, Ni and Ag, each of which tend to have a negative effect on lifetime. In order to design more reliable interconnects, the experimental observation of cracking mechanisms is necessary for the correct application of existing theories. The goal of this research is to observe the failure modes resulting from mode II strain and to determine the damage mechanisms which describe fatigue failures in 95.5 Sn- 4.0 Ag - 0.5 Cu wt% (SAC405) lead-free solder interconnects. In this work the initiation sites and crack paths were characterized for SAC405 ball-grid array (BGA) interconnects with electroless-nickel immersion-gold (ENIG) pad-finish. The interconnects were arranged in a perimeter array and tested in fully assembled packages. Evaluation methods included monotonic and displacement controlled mechanical shear fatigue tests, and temperature cycling. The specimens were characterized using metallogaphy, including optical and electron microscopy as well as energy dispersive spectroscopy (EDS) and precise real-time electrical resistance structural health monitoring (SHM). In mechanical shear fatigue tests, strain was applied by the substrates, simulating dissimilar coefficients of thermal expansion (CTE) between the board and chip-carrier. This type of strain caused cracks to initiate in the soft Sn-rich solder and grow near the interface between the solder and intermetallic compounds (IMC). The growth near

  14. [Intra-circadian neurophysiologic characteristics of the sleep-wakefulness cycle of the white rat].

    Science.gov (United States)

    Bogoslovskiĭ, M M; Karmanova, I G; Piskareva, T V

    1987-03-01

    A number of new or inadequately studied electrophysiological patterns were found in the diurnal organization of wakefulness--sleep cycle in white rats. The analysis of these patterns in view of comparative--physiological approach gives every reason to believe that the structure of white rats sleep reflects evolutionary regularities involved in establishing sleep phases in vertebrates.

  15. Family Forest Owner Characteristics Shaped by Life Cycle, Cohort, and Period Effects

    Science.gov (United States)

    Sarah M. Butler; Brett J. Butler; Marla Markowski-Lindsay

    2017-01-01

    Understanding differences and similarities among family forest owners is important in the context of forest land conservation. This study assesses similarities and differences in landowners by analyzing life cycle effects, cohort differences, and period-specific events that shape people's attitudes and behaviors towards their forestland over time. Using data...

  16. Hydrogen gas filling into an actual tank at high pressure and optimization of its thermal characteristics

    Science.gov (United States)

    Khan, Md. Tawhidul Islam; Monde, Masanori; Setoguchi, Toshiaki

    2009-09-01

    Gas with high pressure is widely used at present as fuel storage mode for different hydrogen vehicles. Different types of materials are used for constructing these hydrogen pressure vessels. An aluminum lined vessel and typically carbon fiber reinforced plastic (CFRP) materials are commercially used in hydrogen vessels. An aluminum lined vessel is easy to construct and posses high thermal conductivity compared to other commercially available vessels. However, compared to CFRP lined vessel, it has low strength capacity and safety factors. Therefore, nowadays, CFRP lined vessels are becoming more popular in hydrogen vehicles. Moreover, CFRP lined vessel has an advantage of light weight. CFRP, although, has many desirable properties in reducing the weight and in increasing the strength, it is also necessary to keep the material temperature below 85 °C for maintaining stringent safety requirements. While filling process occurs, the temperature can be exceeded due to the compression works of the gas flow. Therefore, it is very important to optimize the hydrogen filling system to avoid the crossing of the critical limit of the temperature rise. Computer-aided simulation has been conducted to characterize the hydrogen filling to optimize the technique. Three types of hydrogen vessels with different volumes have been analyzed for optimizing the charging characteristics of hydrogen to test vessels. Gas temperatures are measured inside representative vessels in the supply reservoirs (H2 storages) and at the inlet to the test tank during filling.

  17. Simulation of Image Performance Characteristics of the Landsat Data Continuity Mission (LDCM) Thermal Infrared Sensor (TIRS)

    Science.gov (United States)

    Schott, John; Gerace, Aaron; Brown, Scott; Gartley, Michael; Montanaro, Matthew; Reuter, Dennis C.

    2012-01-01

    The next Landsat satellite, which is scheduled for launch in early 2013, will carry two instruments: the Operational Land Imager (OLI) and the Thermal Infrared Sensor (TIRS). Significant design changes over previous Landsat instruments have been made to these sensors to potentially enhance the quality of Landsat image data. TIRS, which is the focus of this study, is a dual-band instrument that uses a push-broom style architecture to collect data. To help understand the impact of design trades during instrument build, an effort was initiated to model TIRS imagery. The Digital Imaging and Remote Sensing Image Generation (DIRSIG) tool was used to produce synthetic "on-orbit" TIRS data with detailed radiometric, geometric, and digital image characteristics. This work presents several studies that used DIRSIG simulated TIRS data to test the impact of engineering performance data on image quality in an effort to determine if the image data meet specifications or, in the event that they do not, to determine if the resulting image data are still acceptable.

  18. Thermal Degradation Characteristics of Oil Filled Cable Joint with Extremely Degraded tan δ Oil

    Science.gov (United States)

    Ide, Kenichi; Nakade, Masahiko; Takahashi, Tohru; Nakajima, Takenori

    Much of oil filled (OF) cable has been used for a long time for 66∼500kV extra high voltage cable. Sometimes we can see extremely degraded tanδ oil (several tens % of tanδ, for example) in joint box etc. The calculation results of tanδ on a simple combination model of paper/oil show that, tanδ of oil impregnated paper with such a high tanδ oil is extremely high and it must result in a thermal breakdown. However such an event has not taken place up to the present in actually operated transmission line. This fact suggests that some suppression mechanism of tanδ has acted in the degraded tanδ oil impregnated paper insulation. Therefore we investigated the tanδ characteristics of oil impregnated paper with extremely high tanδ oil in detail. In addition, based on the investigation results, we developed a simulation method of heat generation by dielectric loss in OF cable joint (which has degraded tanδ oil).

  19. Detection of Lard in Cocoa Butter—Its Fatty Acid Composition, Triacylglycerol Profiles, and Thermal Characteristics

    Directory of Open Access Journals (Sweden)

    Marliana Azir

    2017-11-01

    Full Text Available The present study investigates the detection of lard in cocoa butter through changes in fatty acids composition, triacylglycerols profile, and thermal characteristics. Cocoa butter was mixed with 1% to 30% (v/v of lard and analyzed using a gas chromatography flame ionization detector, high performance liquid chromatography, and differential scanning calorimetry. The results revealed that the mixing of lard in cocoa butter showed an increased amount of oleic acid in the cocoa butter while there was a decrease in the amount of palmitic acid and stearic acids. The amount of POS, SOS, and POP also decreased with the addition of lard. A heating thermogram from the DSC analysis showed that as the concentration of lard increased from 3% to 30%, two minor peaks at −26 °C and 34.5 °C started to appear and a minor peak at 34.5 °C gradually overlapped with the neighbouring major peak. A cooling thermogram of the above adulterated cocoa butter showed a minor peak shift to a lower temperature of −36 °C to −41.5 °C. Values from this study could be used as a basis for the identification of lard from other fats in the food authentication process.

  20. Caesalpinia echinata Lam. - BRAZILWOOD: THERMAL BEHAVIOR, STRUCTURAL CHARACTERISTICS, AND RESISTANCE TO BIODETERIORATION IN STATIC SYSTEMS

    Directory of Open Access Journals (Sweden)

    Ana Paula Pinto Pinheiro

    Full Text Available ABSTRACT Wood is the best-known biological material used as a raw material since the dawn of mankind until present days. As a natural and renewable composite, its lifetime is limited by the degradation of its basic elements. This degradation can be caused by chemical reactions or by biological agents capable of accelerating the process of deterioration. In this work, the wear, thermal, and micro-structural characteristics, as also the bio-degradation behavior in static systems, of the wood species Brazilwood (Caesalpinia echinata were studied under laboratory conditions in order to use these woods in design. The results show that Brazilwood has a good visual performance after abrasion test, since it has not shown any representative roughness increase. In addition, Brazilwood has high level of crystallinity of, approximately, 68% and was almost insensitive to fungi attack, forming only 5.3 x 103 CFU/mL. Besides, its texture did not change due to exposure to water or sweat.

  1. Study on the Characteristics of Expander Power Output Used for Offsetting Pumping Work Consumption in Organic Rankine Cycles

    Directory of Open Access Journals (Sweden)

    Yu-Ting Wu

    2014-07-01

    Full Text Available The circulation pump in an organic Rankine cycle (ORC increases the pressure of the liquid working fluid from low condensing pressure to high evaporating pressure, and the expander utilizes the pressure difference to generate work. A portion of the expander output power is used to offset the consumed pumping work, and the rest of the expander power is exactly the net work produced by the ORC system. Because of the relatively great theoretical pumping work and very low efficiency of the circulation pump reported in previous papers, the characteristics of the expander power used for offsetting the pumping work need serious consideration. In particular, the present work examines those characteristics. It is found that the characteristics of the expander power used for offsetting the pumping work are satisfactory only under the condition that the working fluid absorbs sufficient heat in the evaporator and its specific volume at the evaporator outlet is larger than or equal to a threshold value.

  2. The Role of Elastic and Plastic Anisotropy of Sn in Recrystallization and Damage Evolution During Thermal Cycling in SAC305 Solder Joints

    Science.gov (United States)

    Bieler, Thomas R.; Zhou, Bite; Blair, Lauren; Zamiri, Amir; Darbandi, Payam; Pourboghrat, Farhang; Lee, Tae-Kyu; Liu, Kuo-Chuan

    2012-02-01

    Because failures in lead-free solder joints occur at locations other than the most highly shear-strained regions, reliability prediction is challenging. To gain physical understanding of this phenomenon, physically based understanding of how elastic and plastic deformation anisotropy affect microstructural evolution during thermomechanical cycling is necessary. Upon solidification, SAC305 (Sn-3.0Ag-0.5Cu) solder joints are usually single or tricrystals. The evolution of microstructures and properties is characterized statistically using optical and orientation imaging microscopy. In situ synchrotron x-ray measurements during thermal cycling are used to examine how crystal orientation and thermal cycling history change strain history. Extensive characterization of a low-stress plastic ball grid array (PBGA) package design at different stages of cycling history is compared with preliminary experiments using higher-stress package designs. With time and thermal history, microstructural evolution occurs mostly from continuous recrystallization and particle coarsening that is unique to each joint, because of the specific interaction between local thermal and displacement boundary conditions and the strong anisotropic elastic, plastic, expansion, and diffusional properties of Sn crystals. The rate of development of recrystallized microstructures is a strong function of strain and aging. Cracks form at recrystallized (random) boundaries, and then percolate through recrystallized regions. Complications arising from electromigration and corrosion are also considered.

  3. The Role of Elastic and Plastic Anisotropy of Sn in Recrystallization and Damage Evolution During Thermal Cycling in SAC305 Solder Joints

    Energy Technology Data Exchange (ETDEWEB)

    Bieler, Thomas R.; Zhou, Bite; Blair, Lauren; Zamiri, Amir; Darbandi, Payam; Pourboghrat, Farhang; Lee, Tae-Kyu; Liu, Kuo-Chuan (Michigan); (Cisco)

    2013-04-08

    Because failures in lead-free solder joints occur at locations other than the most highly shear-strained regions, reliability prediction is challenging. To gain physical understanding of this phenomenon, physically based understanding of how elastic and plastic deformation anisotropy affect microstructural evolution during thermomechanical cycling is necessary. Upon solidification, SAC305 (Sn-3.0Ag-0.5Cu) solder joints are usually single or tricrystals. The evolution of microstructures and properties is characterized statistically using optical and orientation imaging microscopy. In situ synchrotron x-ray measurements during thermal cycling are used to examine how crystal orientation and thermal cycling history change strain history. Extensive characterization of a low-stress plastic ball grid array (PBGA) package design at different stages of cycling history is compared with preliminary experiments using higher-stress package designs. With time and thermal history, microstructural evolution occurs mostly from continuous recrystallization and particle coarsening that is unique to each joint, because of the specific interaction between local thermal and displacement boundary conditions and the strong anisotropic elastic, plastic, expansion, and diffusional properties of Sn crystals. The rate of development of recrystallized microstructures is a strong function of strain and aging. Cracks form at recrystallized (random) boundaries, and then percolate through recrystallized regions. Complications arising from electromigration and corrosion are also considered.

  4. The Effect of Oil Contamination on Evaporator Heat Transfer Characteristics of CO2 Refrigeration Cycle

    Science.gov (United States)

    Katsuta, Masafumi; Kinpara, Hiromitsu; Yagi, Shunta; Mukaiyama, Hiroshi

    Because of the destructions of ozone layers and global warming, it is urgently necessary to abolish fluorocarbon refrigerants of HFCs and substitute them with natural refrigerants. Among several choices of natural refrigerants, CO2, which has an excellent thermal property, has the advantage for practical application. However, heat transfer coefficient and pressure drop of evaporator have not studied enough. No available correlation has been established. The refrigerant of CO2 is extremely sensitive to oil. Therefore, the research on the refrigerant under the circumstances that it is mixed with oil is very limited. It is the purpose of this research to examine the oil mixing effects on thermal and fluid dynamic behaviors and establish correlation.

  5. In-Situ Measurement of Power Loss for Crystalline Silicon Modules Undergoing Thermal Cycling and Mechanical Loading Stress Testing: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Spataru, Sergiu; Hacke, Pater; Sera, Dezso

    2015-09-15

    We analyze the degradation of multi-crystalline silicon photovoltaic modules undergoing simultaneous thermal, mechanical, and humidity stress testing to develop a dark environmental chamber in-situ measurement procedure for determining module power loss. From the analysis we determine three main categories of failure modes associated with the module degradation consisting of: shunting, recombination losses, increased series resistance losses, and current mismatch losses associated with a decrease in photo-current generation by removal of some cell areas due to cell fractures. Based on the analysis, we propose an in-situ module power loss monitoring procedure that relies on dark current-voltage measurements taken during the stress test, and initial and final module flash testing, to determine the power degradation characteristic of the module.

  6. Extracting Concrete Thermal Characteristics from Temperature Time History of RC Column Exposed to Standard Fire

    Directory of Open Access Journals (Sweden)

    Jung J. Kim

    2014-01-01

    Full Text Available A numerical method to identify thermal conductivity from time history of one-dimensional temperature variations in thermal unsteady-state is proposed. The numerical method considers the change of specific heat and thermal conductivity with respect to temperature. Fire test of reinforced concrete (RC columns was conducted using a standard fire to obtain time history of temperature variations in the column section. A thermal equilibrium model in unsteady-state condition was developed. The thermal conductivity of concrete was then determined by optimizing the numerical solution of the model to meet the observed time history of temperature variations. The determined thermal conductivity with respect to temperature was then verified against standard thermal conductivity measurements of concrete bricks. It is concluded that the proposed method can be used to conservatively estimate thermal conductivity of concrete for design purpose. Finally, the thermal radiation properties of concrete for the RC column were estimated from the thermal equilibrium at the surface of the column. The radiant heat transfer ratio of concrete representing absorptivity to emissivity ratio of concrete during fire was evaluated and is suggested as a concrete criterion that can be used in fire safety assessment.

  7. Surface Characteristics and High Cycle Fatigue Performance of Shot Peened Magnesium Alloy ZK60

    Directory of Open Access Journals (Sweden)

    Jie Dong

    2011-01-01

    Full Text Available The current work investigated the effect of shot peening (SP on high cycle fatigue (HCF behavior of the hot-extruded ZK60 magnesium alloy. SP can significantly improve the fatigue life of the ZK60 alloy. After SP at the optimum Almen intensities, the fatigue strength at 107 cycles in the as-extruded (referred to as ZK60 and the T5 aging-treated (referred to as ZK60-T5 alloys increased from 140 and 150 MPa to 180 and 195 MPa, respectively. SP led to a subsurface fatigue crack nucleation in both ZK60 and ZK60-T5 alloys. The mechanism by which the compressive residual stress induced by shot peening results in the improvement of fatigue performance for ZK60 and ZK60-T5 alloys was discussed.

  8. Effects of High Temperature and Thermal Cycling on the Performance of Perovskite Solar Cells: Acceleration of Charge Recombination and Deterioration of Charge Extraction.

    Science.gov (United States)

    Sheikh, Arif D; Munir, Rahim; Haque, Md Azimul; Bera, Ashok; Hu, Weijin; Shaikh, Parvez; Amassian, Aram; Wu, Tom

    2017-10-11

    In this work, we investigated the effects of high operating temperature and thermal cycling on the photovoltaic (PV) performance of perovskite solar cells (PSCs) with a typical mesostructured (m)-TiO2-CH3NH3PbI3-xClx-spiro-OMeTAD architecture. After temperature-dependent grazing-incidence wide-angle X-ray scattering, in situ X-ray diffraction, and optical absorption experiments were carried out, the thermal durability of PSCs was tested by subjecting the devices to repetitive heating to 70 °C and cooling to room temperature (20 °C). An unexpected regenerative effect was observed after the first thermal cycle; the average power conversion efficiency (PCE) increased by approximately 10% in reference to the as-prepared device. This increase of PCE was attributed to the heating-induced improvement of the crystallinity and p doping in the hole transporter, spiro-OMeTAD, which promotes the efficient extraction of photogenerated carriers. However, further thermal cycles produced a detrimental effect on the PV performance of PSCs, with the short-circuit current and fill factor degrading faster than the open-circuit voltage. Similarly, the PV performance of PSCs degraded at high operation temperatures; both the short-circuit current and open-circuit voltage decreased with increasing temperature, but the temperature-dependent trend of the fill factor was the opposite. Our impedance spectroscopy analysis revealed a monotonous increase of the charge-transfer resistance and a concurrent decrease of the charge-recombination resistance with increasing temperature, indicating a high recombination of charge carriers. Our results revealed that both thermal cycling and high temperatures produce irreversible detrimental effects on the PSC performance because of the deteriorated interfacial photocarrier extraction. The present findings suggest that the development of robust charge transporters and proper interface engineering are critical for the deployment of perovskite PVs in harsh

  9. Effects of High Temperature and Thermal Cycling on the Performance of Perovskite Solar Cells: Acceleration of Charge Recombination and Deterioration of Charge Extraction

    KAUST Repository

    Sheikh, Arif D.

    2017-09-18

    In this work, we investigated the effects of high operating temperature and thermal cycling on the photovoltaic performance of perovskite solar cells (PSCs) with a typical mesostructured (m)-TiO2-CH3NH3PbI3-xClx-spiro-OMeTAD architecture. After carrying out temperature-dependent grazing incidence wide-angle X-ray scattering (GIWAXS), in-situ X-ray diffraction (XRD) and optical absorption experiments, thermal durability of PSCs was tested by subjecting the devices to repetitive heating to 70 °C and cooling to room temperature (20 °C). An unexpected regenerative effect was observed after the first thermal cycle; the average power conversion efficiency (PCE) increased by approximately 10 % in reference to the as-prepared device. This increase of PCE was attributed to the heating-induced improvement of crystallinity and p-doping in the hole-transporter, Spiro-OMeTAD, which promotes the efficient extraction of photo-generated carriers. However, further thermal cycles produced a detrimental effect on the photovoltaic performance of PSCs with short-circuit current and fill factor degrading faster than the open-circuit voltage. Similarly, the photovoltaic performance of PSCs degraded at high operation temperatures; both short-circuit current and open-circuit voltage decreased with increasing temperature, but the temperature-dependent trend of fill factor was opposite. Our impedance spectroscopy analysis revealed a monotonous increase of charge transfer resistance and a concurrent decrease of charge recombination resistance with increasing temperature, indicating high recombination of charge carriers. Our results revealed that both thermal cycling and high temperatures produce irreversible detrimental effects on the PSC performance due to the deteriorated interfacial photo-carrier extraction. The present findings suggest that development of robust charge transporters and proper interface engineering are critical for the deployment of perovskite photovoltaics in harsh

  10. Effect of Turf Roof Slabs on Indoor Thermal Performance in Tropical Climates: A Life Cycle Cost Approach

    Directory of Open Access Journals (Sweden)

    R. U. Halwatura

    2013-01-01

    Full Text Available Urbanization related to population growth is one of the burning issues that the world is facing today. Parallel to this, there is visible evidence of a possible energy crisis in the near future. Thus, scientists have paid attention to sustainable development methods, and in the field of building construction also, several innovations have been proposed. For example, green roof concept is one of such which is considered a viable method mainly to reduce urban heat island effect, to regain lost land spaces in cities, and to increase aesthetics in cities. The present study was aimed at investigating the impact of green roofs on indoor temperature of buildings, the effect of different types of roofs on the air conditioning loads, and the life cycle cost of buildings with different types of roofing. The study was conducted in several phases: initial small-scale models to determine the heat flow characteristics of roof top soil layers with different thicknesses, a large-scale model applying the findings of the small-scale models to determine temperature fluctuations within a building with other common roofing systems, a computer simulation to investigate air conditioning loads in a typical building with cement fiber sheets and green roof slabs, a comparative analysis of the effect of traditional type roofs and green roofs on the air conditioning loads, and finally an analysis to predict the influence of traditional type roofs and green roofs on life cycle cost of the buildings. The main findings of the study were that green roofs are able to reduce the indoor temperature of buildings and are able to achieve better heat transfer through the roof, and, thus a lower cooling load is necessary for air conditioning and has the possibility of reducing life cycle cost of a building.

  11. Thermal Characteristics of Amorphous Indium-Gallium-Zinc-Oxide and Graphite in Display Panel Based Thin Film Transistors.

    Science.gov (United States)

    Kim, Hak-Jun; Kim, Youn-Jea

    2015-11-01

    One of the important design factors in the smart electronic industry is proper heat treatment of the display panel. In order to improve the heat transfer performance of display panels, we analyzed a three-dimensional model of multi-stack layers of the thin film transistors (TFTs). In particular, we numerically investigated the thermal barrier effects of active layers having different material properties of a-IGZO (isotropy) and graphite (anisotropy). We calculated the temperature distribution on the display panel with each active layer, using the commercial code, COMSOL Multiphysics. We graphically depict comparative results of the thermal characteristics between a-IGZO and graphite with the stacked structure of the TFTs.

  12. Evaluation of Thermal Endurance Characteristics of Flexible Polyurethane Foams by Dynamic Compression Modulus

    National Research Council Canada - National Science Library

    Adachi, Hiromasa; Hasegawa, Teruo

    2005-01-01

      For evaluation of thermal endurance in foamed plastics, temperature and time dependence of compression dynamic modulus of four flexible polyurethane foams was investigated by dynamic viscoelastic measurements...

  13. Epidermal photonic devices for quantitative imaging of temperature and thermal transport characteristics of the skin

    National Research Council Canada - National Science Library

    Gao, Li; Zhang, Yihui; Malyarchuk, Viktor; Jia, Lin; Jang, Kyung-In; Webb, R Chad; Fu, Haoran; Shi, Yan; Zhou, Guoyan; Shi, Luke; Shah, Deesha; Huang, Xian; Xu, Baoxing; Yu, Cunjiang; Huang, Yonggang; Rogers, John A

    2014-01-01

    .... Here we introduce an ultrathin, compliant skin-like, or 'epidermal', photonic device that combines colorimetric temperature indicators with wireless stretchable electronics for thermal measurements...

  14. Conceptual Design Study of a Closed Brayton Cycle Turbogenerator for Space Power Thermal-To-Electric Conversion System

    Science.gov (United States)

    Hansen, Jeff L.

    2000-01-01

    A conceptual design study was completed for a 360 kW Helium-Xenon closed Brayton cycle turbogenerator. The selected configuration is comprised of a single-shaft gas turbine engine coupled directly to a high-speed generator. The engine turbomachinery includes a 2.5:1 pressure ratio compression system with an inlet corrected flow of 0.44 kg/sec. The single centrifugal stage impeller discharges into a scroll via a vaned diffuser. The scroll routes the air into the cold side sector of the recuperator. The hot gas exits a nuclear reactor radiator at 1300 K and enters the turbine via a single-vaned scroll. The hot gases are expanded through the turbine and then diffused before entering the hot side sector of the recuperator. The single shaft design is supported by air bearings. The high efficiency shaft mounted permanent magnet generator produces an output of 370 kW at a speed of 60,000 rpm. The total weight of the turbogenerator is estimated to be only 123 kg (less than 5% of the total power plant) and has a volume of approximately 0.11 cubic meters. This turbogenerator is a key element in achieving the 40 to 45% overall power plant thermal efficiency.

  15. Surface phenomena associated with thermal cycling of copper and their impact on the service life of particle accelerator structures

    CERN Document Server

    Aicheler, Markus; Theisen, Werner; Sgobba, Stefano

    2010-01-01

    The performance of accelerating structures (AS) in the Compact LInear Collider (CLIC) is sensitive to a variety of parameters, including the surface quality of key elements of the AS. Processes which affect the surface quality are therefore of particular concern. The present work addresses surface modifications associated with thermal cycling during operation. This type of operating condition represents a specific type of fatigue loading. Four fatigue test procedures were used in the present study in order to investigate the fatigue behaviour of oxygen{free{electronic (OFE) copper, the candidate material of the CLIC-AS: conventional fatigue (CVF), ultrasonic swinger (USS), laser fatigue (LAF) and radio{frequency fatigue (RFF). During operation of the accelerator the material of the AS will be subjected to cyclic temperature changes of approx. Delta T = 56 K, from about 40° C to about 100° C. These temperature changes will result in cyclic biaxial strains in the surface of the order of epsilon(biax) = 9.2 x ...

  16. Environmental Life-Cycle Analysis of Hybrid Solar Photovoltaic/Thermal Systems for Use in Hong Kong

    Directory of Open Access Journals (Sweden)

    Tin-Tai Chow

    2012-01-01

    Full Text Available While sheet-and-tube absorber is generally recommended for flat-plate photovoltaic/thermal (PV/T collector design because of the simplicity and promising performance, the use of rectangular-channel absorber is also tested to be a good alternative. Before a new energy technology, like PV/T, is fully implemented, its environmental superiority over the competing options should be assessed, for instance, by evaluating its consumption levels throughout its production and service life. Although there have been a plenty of environmental life-cycle assessments on the domestic solar hot water systems and PV systems, the related works on hybrid solar PV/T systems have been very few. So far there is no reported work on the assessment of PV/T collector with channel-type absorber design. This paper reports an evaluation of the energy payback time and the greenhouse gas payback time of free-standing and building-integrated PV/T systems in Hong Kong. This is based on two case studies of PV/T collectors with modular channel-type aluminium absorbers. The results confirm the long-term environmental benefits of PV/T applications.

  17. Results of scoping tests for open-cycle OTEC (ocean thermal energy conversion) components operating with seawater

    Energy Technology Data Exchange (ETDEWEB)

    Zangrando, F; Bharathan, D; Green, H J; Link, H F; Parsons, B K; Parsons, J M; Pesaran, A A [Solar Energy Research Inst., Golden, CO (USA); Panchal, C B [Argonne National Lab., IL (USA)

    1990-09-01

    This report presents comprehensive documentation of the experimental research conducted on open-cycle ocean thermal energy conversion (OC-OTEC) components operating with seawater as a working fluid. The results of this research are presented in the context of previous analysis and fresh-water testing; they provide a basis for understanding and predicting with confidence the performance of all components of an OC-OTEC system except the turbine. Seawater tests have confirmed the results that were obtained in fresh-water tests and predicted by the analytical models of the components. A sound technical basis has been established for the design of larger systems in which net power will be produced for the first time from OC-OTEC technology. Design and operation of a complete OC-OTEC system that produces power will provide sufficient confidence to warrant complete transfer of OC-OTEC technology to the private sector. Each components performance is described in a separate chapter written by the principal investigator responsible for technical aspects of the specific tests. Chapters have been indexed separately for inclusion on the data base.

  18. Photo-thermal characteristics of water-based Fe3O4@SiO2 nanofluid for solar-thermal applications

    Science.gov (United States)

    Khashan, Saud; Dagher, Sawsan; Omari, Salahaddin Al; Tit, Nacir; Elnajjar, Emad; Mathew, Bobby; Hilal-Alnaqbi, Ali

    2017-05-01

    This work proposes and demonstrates the novel idea of using Fe3O4@SiO2 core/shell structure nanoparticles (NPs) to improve the solar thermal conversion efficiency. Magnetite (Fe3O4) NPs are synthesized by controlled co-precipitation method. Fe3O4@SiO2 NPs are prepared based on sol-gel approach, then characterized. Water-based Fe3O4@SiO2 nanofluid is prepared and usedto illustrate the photo-thermal conversion characteristics of a solar collector under solar simulator. The temperature rise characteristics of the nanofluids are investigated at different heights of the solar collector, for duration of 300 min, under a solar intensity of 1000 W m-2. The experimental results show that Fe3O4@SiO2 NPs have a core/shell structure with spherical morphology and size of about 400 nm. Fe3O4@SiO2/H2O nanofluid enhances the photo-thermal conversion efficiency compared with base fluid and Fe3O4/H2O nanofluid, since the silica coating improves both the thermodynamic stability of the nanofluid and the light absorption effectiveness of the NPs. At a concentration of 1 mg/1 ml of Fe3O4@SiO2/H2O, and with the utilization of kerosene into the solar collector, and exposure for radiation for 5 min, the photo-thermal conversion efficiency has shown an enhancement at the bottom of the collector of about 32.9% compared to the base fluid.

  19. Effect of airborne-particle abrasion and mechanico-thermal cycling on the flexural strength of glass ceramic fused to gold or cobalt-chromium alloy.

    Science.gov (United States)

    Oliveira de Vasconcellos, Luis Gustavo; Silva, Lucas H; Reis de Vasconcellos, Luana Marotta; Balducci, Ivan; Takahashi, Fernando E; Bottino, Marco Antonio

    2011-10-01

    To evaluate the effect of airborne-particle abrasion and mechanico-thermal cycling on the flexural strength of a ceramic fused to cobalt-chromium alloy or gold alloy. Metallic bars (n = 120) were made (25 mm × 3 mm × 0.5 mm): 60 with gold alloy and 60 with Co-Cr. At the central area of the bars (8 mm × 3 mm), a layer of opaque ceramic and then two layers of glass ceramic (Vita VM13, Vita Zahnfabrick) were fired onto it (thickness: 1 mm). Ten specimens from each alloy group were randomly allocated to a surface treatment [(tungsten bur or air-particle abrasion (APA) with Al(2) O(3) at 10 mm or 20 mm away)] and mechanico-thermal cycling (no cycling or mechanically loaded 20,000 cycles; 10 N distilled water at 37°C and then thermocycled 3000 cycles; 5°C to 55°C, dwell time 30 seconds) combination. Those specimens that did not undergo mechanico-thermal cycling were stored in water (37°C) for 24 hours. Bond strength was measured using a three-point bend test, according to ISO 9693. After the flexural strength test, failure types were noted. The data were analyzed using three factor-ANOVA and Tukey's test (α= 0.05). There were no significant differences between the flexural bond strength of gold and Co-Cr groups (42.64 ± 8.25 and 43.39 ± 10.89 MPa, respectively). APA 10 and 20 mm away surface treatment (45.86 ± 9.31 and 46.38 ± 8.89 MPa, respectively) had similar mean flexural strength values, and both had significantly higher bond strength than tungsten bur treatment (36.81 ± 7.60 MPa). Mechanico-thermal cycling decreased the mean flexural strength values significantly for all six alloy-surface treatment combinations tested when compared to the control groups. The failure type was adhesive in the metal/ceramic interface for specimens surface treated only with the tungsten bur, and mixed for specimens surface treated with APA 10 and 20 mm. Considering the levels adopted in this study, the alloy did not affect the bond strength; APA with Al(2) O(3) at 10 and

  20. Breathing thermal manikin for indoor environment assessment: Important characteristics and requirements

    DEFF Research Database (Denmark)

    Melikov, Arsen Krikor

    2003-01-01

    Recently breathing thermal manikins have been developed and used for indoor environment measurement, evaluation and optimization as well as validation of Computational Fluid Dynamics (CFD) predictions of airflow around a human body. Advances in the assessment of occupants¿ thermal comfort and per...

  1. Characteristics of Low-latitude Coronal Holes near the Maximum of Solar Cycle 24

    DEFF Research Database (Denmark)

    Hofmeister, Stefan J.; Veronig, Astrid; Reiss, Martin A.

    2017-01-01

    We investigate the statistics of 288 low-latitude coronal holes extracted from SDO/AIA-193 filtergrams over the time range of 2011 January 01–2013 December 31. We analyze the distribution of characteristic coronal hole properties, such as the areas, mean AIA-193 intensities, and mean magnetic fie...

  2. Daily Cycle of Skewness and Kurtosis Characteristics within and just Above a Crop Canapy

    NARCIS (Netherlands)

    Jacobs, A.F.G.; Wiel, van de B.J.H.; Holtslag, A.A.M.

    2000-01-01

    A measurement program is carried out within as well as above a maize crop canopy. Statistical characteristics are analyzed for the velocity components as well as for temperature for a clear weather day as well as a cloudy day. During daytime it appears that the above and within-canopy

  3. The Characteristic and Classification of Thermal Spring in Ramsar area, North of Iran

    Science.gov (United States)

    Abedsoltan, Farnaz; Ansari, Mohammad Reza; Gafari, Mohammad Reza

    2010-05-01

    Ramsar area is located across and between Alborze Mountain and Caspine Sea in North of Iran. About 30 spas are located south of the Ramsar and Sadatshar town. They are almost in between 20 to 70 m elevation. Paleozoic, Mesozoic and Tertiary rocks and alluvial deposit are exposed around the Ramsar area. In tertiary, acidic Plutonism was active and intrusion into the Paleozoic and Mesozoic formations. Quaternary and Alluvium deposits are exposed and extending on the Jurassic formations in Ramsar plain and have thickness lower than 10 m in show springs. The annual precipitation in the Ramsar region is 976 mm. There has not any proper Thermal spring management in Ramsar area yet. This could post some serious problem on improper management of Thermal spring sites, where its environment has been put into jeopardy. This study aims to provide a way to classify the Thermal springs in Ramsar area. The result of this study help in the classification of Thermal spring sites for official planning improvement of administration and sustainable development of natural resources of the area. The study makes use of the Department Applied Geosciences in Islamic Azad University and GIS data of a total of 9 Thermal springs in the attempt to set up a classification system of Thermal springs in Ramsar area. These data include surface temperature, conductivity, alkalinity, acidity, TDS, pH values, Ca, Cl, Fe, K, Mg, Mn, Na, SiO2, SO4 contents, their locations, usages and other relevant information. The surface temperature of Thermal springs are between 19oC - 65oC and SiO2 geothermometer shows estimated reservoir temperature range from 86 o C - 96 o C. Most of the water from these Thermal springs is relatively turbidness and their composition is sodium choloride. The Thermal springs in this area generally exhibit high SiO2 and Na content; strong smell of sulfur. In addition, there are 30 Thermal springs located in Ramsar area and that show high concentration of Cl, Ca, Na, K and Mg. There

  4. Development of nuclear transmutation technology - A study on the thermal-hydraulic characteristics of Pb-Bi coolant material

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Chang Hyun; You, Young Woo; Cho, Jae Seon; Kim, Ju Youl; Yang, Hui Chang; Huh, Byung Gil [Seoul National University, Seoul (Korea)

    2000-03-01

    The objective of this study is to provide the direction of HYPER design in terms of thermal hydraulics especially through the analysis of thermal hydraulic characteristics of lead-bismuth material as a HYPER coolant and of proton accelerator target system. In this study, in order to evaluate the thermal-hydraulic characteristics of HYPER system, the FLUENT calculation is performed with liquid metal lead-bismuth(43%) and the turbulent Prandtl number model is developed. Also, the heat transfer analyses including temperature rising are performed for accelerator beam window, solid tungsten target and liquid target which is composed of liquid lead and lead-bismuth, respectively and the thermal stress analyses are performed for accelerator beam window. Through this study, the BASECASE whose parameter is HYPER system design specification is calculated by FLUENT. It is shown that the coolant velocity must exceeds 1.6 m/s for supporting the core coolant temperature in operating temperature range. The suggested turbulent Prandtl number model is applicable to liquid metal. And in order to maintain the integrity of proton beam target system, it is necessary to investigate the target structure associated with smoothing the flow path and beam window cooling. 43 refs., 67 figs., 27 tabs. (Author)

  5. A comparative study of thermal characteristics of GaN-based VCSELs with three different typical structures

    Science.gov (United States)

    Mei, Yang; Xu, Rong-Bin; Xu, Huan; Ying, Lei-Ying; Zheng, Zhi-Wei; Zhang, Bao-Ping; Li, Mo; Zhang, Jian

    2018-01-01

    Thermal characteristics of GaN-based vertical cavity surface emitting lasers (VCSELs) with three typical structures were investigated both theoretically and experimentally. The simulation results based on a steady state quasi three-dimensional cylindrical model show that the thermal resistance (R th) is affected by cavity length, mesa size, as well as the bottom distributed Bragg reflector (DBR) size, and the detail further depends on different structures. Among different devices, GaN VCSEL with a hybrid cavity formed by one nitride bottom DBR and another dielectric top DBR is featured with lower R th, which is meanwhile affected strongly by the materials of the epitaxial bottom DBR. The main issues affecting the thermal dissipation in VCSELs with double dielectric DBRs are the bottom dielectric DBR and the dielectric current-confinement layer. To validate the simulation results, GaN-based VCSEL bonded on a copper plate was fabricated. R th of this device was measured and the results agreed well with the simulation. This work provides a better understanding of the thermal characteristics of GaN-based VCSELs and is useful in optimizing the structure design and improving the device performance.

  6. Thermal characteristics of non-edible oils as phase change materials candidate to application of air conditioning chilled water system

    Science.gov (United States)

    Irsyad, M.; Indartono, Y. S.; Suwono, A.; Pasek, A. D.

    2015-09-01

    The addition of phase change material in the secondary refrigerant has been able to reduce the energy consumption of air conditioning systems in chilled water system. This material has a high thermal density because its energy is stored as latent heat. Based on material melting and freezing point, there are several non-edible oils that can be studied as a phase change material candidate for the application of chilled water systems. Forests and plantations in Indonesia have great potential to produce non-edible oil derived from the seeds of the plant, such as; Calophyllum inophyllum, Jatropha curcas L, and Hevea braziliensis. Based on the melting temperature, these oils can further studied to be used as material mixing in the secondary refrigerant. Thermal characteristics are obtained from the testing of T-history, Differential Scanning Calorimetric (DSC) and thermal conductivity materials. Test results showed an increase in the value of the latent heat when mixed with water with the addition of surfactant. Thermal characteristics of each material of the test results are shown completely in discussion section of this article.

  7. Thermal conductivity of polymer composites with the geometrical characteristics of graphene nanoplatelets.

    Science.gov (United States)

    Kim, Hyun Su; Bae, Hyun Sung; Yu, Jaesang; Kim, Seong Yun

    2016-05-25

    One of the most important physical factors related to the thermal conductivity of composites filled with graphene nanoplatelets (GNPs) is the dimensions of the GNPs, that is, their lateral size and thickness. In this study, we reveal the relationship between the thermal conductivity of polymer composites and the realistic size of GNP fillers within the polymer composites (measured using three-dimensional (3D) non-destructive micro X-ray CT analysis) while minimizing the effects of the physical parameters other than size. A larger lateral size and thickness of the GNPs increased the likelihood of the matrix-bonded interface being reduced, resulting in an effective improvement in the thermal conductivity and in the heat dissipation ability of the composites. The thermal conductivity was improved by up to 121% according to the filler size; the highest bulk and in-plane thermal conductivity values of the composites filled with 20 wt% GNPs were 1.8 and 7.3 W/m·K, respectively. The bulk and in-plane thermal conductivity values increased by 650 and 2,942%, respectively, when compared to the thermal conductivity values of the polymer matrix employed (0.24 W/m·K).

  8. Thermal conductivity of polymer composites with the geometrical characteristics of graphene nanoplatelets

    Science.gov (United States)

    Kim, Hyun Su; Bae, Hyun Sung; Yu, Jaesang; Kim, Seong Yun

    2016-01-01

    One of the most important physical factors related to the thermal conductivity of composites filled with graphene nanoplatelets (GNPs) is the dimensions of the GNPs, that is, their lateral size and thickness. In this study, we reveal the relationship between the thermal conductivity of polymer composites and the realistic size of GNP fillers within the polymer composites (measured using three-dimensional (3D) non-destructive micro X-ray CT analysis) while minimizing the effects of the physical parameters other than size. A larger lateral size and thickness of the GNPs increased the likelihood of the matrix-bonded interface being reduced, resulting in an effective improvement in the thermal conductivity and in the heat dissipation ability of the composites. The thermal conductivity was improved by up to 121% according to the filler size; the highest bulk and in-plane thermal conductivity values of the composites filled with 20 wt% GNPs were 1.8 and 7.3 W/m·K, respectively. The bulk and in-plane thermal conductivity values increased by 650 and 2,942%, respectively, when compared to the thermal conductivity values of the polymer matrix employed (0.24 W/m·K). PMID:27220415

  9. Characteristics of Low-latitude Coronal Holes near the Maximum of Solar Cycle 24

    Energy Technology Data Exchange (ETDEWEB)

    Hofmeister, Stefan J.; Veronig, Astrid; Reiss, Martin A.; Temmer, Manuela [University of Graz, Institute of Physics, IGAM-Kanzelhöhe Observatory, Graz (Austria); Vennerstrom, Susanne [National Space Institute, DTU Space (Denmark); Vršnak, Bojan [Hvar Observatory, Faculty of Geodesy, Zagreb (Croatia); Heber, Bernd, E-mail: stefan.hofmeister@uni-graz.at [Universität Kiel, Institut für Experimentelle und Angewandte Physik, Kiel (Germany)

    2017-02-01

    We investigate the statistics of 288 low-latitude coronal holes extracted from SDO /AIA-193 filtergrams over the time range of 2011 January 01–2013 December 31. We analyze the distribution of characteristic coronal hole properties, such as the areas, mean AIA-193 intensities, and mean magnetic field densities, the local distribution of the SDO /AIA-193 intensity and the magnetic field within the coronal holes, and the distribution of magnetic flux tubes in coronal holes. We find that the mean magnetic field density of all coronal holes under study is 3.0 ± 1.6 G, and the percentaged unbalanced magnetic flux is 49 ± 16%. The mean magnetic field density, the mean unsigned magnetic field density, and the percentaged unbalanced magnetic flux of coronal holes depend strongly pairwise on each other, with correlation coefficients cc > 0.92. Furthermore, we find that the unbalanced magnetic flux of the coronal holes is predominantly concentrated in magnetic flux tubes: 38% (81%) of the unbalanced magnetic flux of coronal holes arises from only 1% (10%) of the coronal hole area, clustered in magnetic flux tubes with field strengths >50 G (10 G). The average magnetic field density and the unbalanced magnetic flux derived from the magnetic flux tubes correlate with the mean magnetic field density and the unbalanced magnetic flux of the overall coronal hole (cc>0.93). These findings give evidence that the overall magnetic characteristics of coronal holes are governed by the characteristics of the magnetic flux tubes.

  10. Spatio-temporal characteristics of the diurnal precipitation cycle over Sweden and the linkage to large-scale circulation

    Science.gov (United States)

    Walther, A.; Jeong, J.-H.; Chen, D.

    2009-04-01

    Rainfall events exhibit diurnal cycle in both frequency and amount, of which phase and amplitude show substantial geographic and seasonal variation. Although the diurnal cycle of precipitation is one of the fundamental characteristics to determine local weather and climate, most of sophisticated climate models still have great deficiencies in reproducing it. Thus more exact understanding of the diurnal precipitation cycle and its mechanisms is thought to be very important to improve climate models and their prediction results. In this work we investigate the diurnal cycle of precipitation in Sweden using ground based hourly observations for 1996-2008. For the precipitation amount and frequency, mean diurnal cycles are computed, and the peak timing and amplitude of the diurnal and semi-diurnal cycle of precipitation are estimated by the harmonic analysis method. Clear mean diurnal precipitation cycles as well as distinct spatial patterns for all seasons are derived. In summer, showing the most distinct pattern, the majority of the stations show a clear rainfall maximum in the afternoon (12-18 LST) except for the coastal part of Central Sweden where we see an early-morning peak (00-06 LST) and the east coast of southern Sweden where we find a morning peak (06-12 LST). The clear afternoon peak may be due to high insolation accumulated during the day time in summer leading to a local convection activity later on that day. These coastal bands mostly consist of the stations closest to the Baltic Sea. Meso-scale convection connected to temperature differences between sea and land combined with a favorable wind pattern seems to play a role here. In the transition seasons, spring and autumn, the amplitude is weaker and the spatial pattern of peak timing is less distinct than in summer. In spring the westcoast stations have a morning peak and stations in southeastern Sweden show an afternoon peak. In autumn we see a zonal division with a clear afternoon peak in southern

  11. Measurement of two-dimensional thermal neutron flux in a water phantom and evaluation of dose distribution characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Kazuyoshi; Kumada, Hiroaki; Kishi, Toshiaki; Torii, Yoshiya; Horiguchi, Yoji [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-03-01

    To evaluate nitrogen dose, boron dose and gamma-ray dose occurred by neutron capture reaction of the hydrogen at the medical irradiation, two-dimensional distribution of the thermal neutron flux is very important because these doses are proportional to the thermal neutron distribution. This report describes the measurement of the two-dimensional thermal neutron distribution in a head water phantom by neutron beams of the JRR-4 and evaluation of the dose distribution characteristic. Thermal neutron flux in the phantom was measured by gold wire placed in the spokewise of every 30 degrees in order to avoid the interaction. Distribution of the thermal neutron flux was also calculated using two-dimensional Lagrange's interpolation program (radius, angle direction) developed this time. As a result of the analysis, it was confirmed to become distorted distribution which has annular peak at outside of the void, though improved dose profile of the deep direction was confirmed in the case which the radiation field in the phantom contains void. (author)

  12. Thermal Response and Stability Characteristics of Bistable Composite Laminates by Considering Temperature Dependent Material Properties and Resin Layers

    Science.gov (United States)

    Moore, M.; Ziaei-Rad, S.; Salehi, H.

    2013-02-01

    In this study, the stability characteristics and thermal response of a bistable composite plate with different asymmetric composition were considered. The non-linear finite element method (FEM) was utilized to determine the response of the laminate. Attention was focused on the temperature dependency of laminate mechanical properties, especially on the thermal expansion coefficients of the composite graphite-epoxy plate. Also the effect of including the resin layers on the stability characteristics of the laminate was investigated. The effect of the temperature on the laminate cured configurations in the range of 25°C to 180°C and -60°C to 40°C was examined. The results indicate that the coefficient of thermal expansions has a major effect on the cured shapes. Next, optical microscopy was used to characterize the laminate composition and for the first time the effect of including the resin layers on the actuation loads that causes snapping behavior between two stable shapes was studied. The results obtained from the finite element simulations were compared with experimental results and a good correlation was obtained. Finally, the stability characteristics of a tapered composite panel were investigated for using in a sample winglet as a candidate application of bistable structures.

  13. PREDICTIVE VALUE OF THE ECHOGRAPHIC CHARACTERISTICS OF ENDOMETRIUM ON IMPLANTATION RATE IN IN-VITRO FERTILIZATION IN UNSTIMULATED CYCLE

    Directory of Open Access Journals (Sweden)

    Lucija Kuder

    2002-12-01

    Full Text Available Background. The purpose of this study was to determine whether endometrial features such as thickness, type and subendometrial movements observed by ultrasound on the day of embryo transfer in in vitro fertilisation (IVF in natural cycles, can predict implantation outcome.Methods. One hundred and eight natural IVF cycles in which the embryo transfer was performed were included in a prospective study. One hour prior to embryo transfer vaginal ultrasound examination was done to measure endometrial thickness, asses endometrial pattern and movements. The thickness and the type of endometrium were estimated in sagital plane of the uterus. Estimations of the direction of movements, amplitude and the amount of waves regarding the length of uterine cavity were performed. Women were divided into two groups: the first group consisted of those who conceived and the second of those who did not.Results. The average age of women was 32.8 ± 4.07 years. Both groups were comparable in terms of age, estradiol level and average follicle diameter on the day of hCG application. Pregnancy rate on embryo transfer being 22.2% (24/108, and 84 women (77.8% did not conceived. The thickness, type and endometrial movements were similar in both groups, therefore, not statistically significant (p > 0.05. Duration of menstrual cycles prior to hCG application in no concived group was shorter, statistically significant (p = 0.002.Conclusions. On the basis owing to ultrasound characteristics such as subendometrial movements, thickness and pattern on the day of embryo transfer in the natural IVF/ICSI cycle have no predictive value of embryo implantation.

  14. Thermal Hydraulic Characteristics of Fuel Defects in Plate Type Nuclear Research Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Bodey, Isaac T [ORNL

    2014-05-01

    Turbulent flow coupled with heat transfer is investigated for a High Flux Isotope Reactor (HFIR) fuel plate. The Reynolds Averaged Navier-Stokes Models are used for fluid dynamics and the transfer of heat from a thermal nuclear fuel plate using the Multi-physics code COMSOL. Simulation outcomes are compared with experimental data from the Advanced Neutron Source Reactor Thermal Hydraulic Test Loop. The computational results for the High Flux Isotope Reactor core system provide a more physically accurate simulation of this system by modeling the turbulent flow field in conjunction with the diffusion of thermal energy within the solid and fluid phases of the model domain. Recommendations are made regarding Nusselt number correlations and material properties for future thermal hydraulic modeling efforts

  15. Experimental investigation on the characteristics of polyethylene glycol/cement composites as thermal energy storage materials

    Energy Technology Data Exchange (ETDEWEB)

    Li, H. [Department of Material Science and Engineering, Nanjing University, Nanjing (China); Fang, G.Y. [School of Physics, Nanjing University, Nanjing (China)

    2010-10-15

    The polyethylene glycol/cement composites as thermal energy storage materials were prepared by blending polyethylene glycol and cement. In composite materials, polyethylene glycol (PEG) is used as the phase change material for thermal energy storage and cement acts as the supporting material. A Fourier transformation infrared spectroscope (FT-IR), X-ray diffractometer (XRD), and scanning electronic microscope (SEM) were used to determine the chemical structure, the crystalloid phase, and microstructure of the polyethylene glycol/cement composites, respectively. The thermal properties and thermal stability were investigated by a differential scanning calorimeter (DSC) and a thermogravimetry analyzer (TGA). The SEM results showed that the polyethylene glycol was well dispersed in the porous network of the cement. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  16. Influence of Interfacial Carbide Layer Characteristics on Thermal Properties of Copper-Diamond Composites (Postprint)

    Science.gov (United States)

    2014-04-01

    contrast, /eff ¼ keffd km , the governing equation per DEM scheme is [29]: ð1 VdÞ ¼ /eff A /eff 1 A 1=3 ð4Þ Acoustic Mismatch Model ( AMM ) for...hc calculation AMM assumes no phonon scattering at the interface [30], and permits an estimation of thermal conductance for Cu/ diamond interface...without needing the thermal conduc- tivities of the composite and its constituents as the input parameters. According to AMM , the Cu/diamond interface

  17. Nuclear and thermal-hydraulic characteristics for an LMR core fueled with 20% enriched uranium metallic fuel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young-In; Kim, Young-Gyun; Kim, Sang-Ji; Kim, Young-Jin

    1999-05-01

    As a part of the core design development of KALIMER (150 MWe), the KALIMER core was initially designed with 20% enriched uranium metallic fuel. In this core design, the primary emphasis was given to realize the metallic fueled core design to meet the specific design requirements; 20% and below uranium enrichment and a minimum fuel cycle length of one year. The core was defined by a radially homogeneous core configuration incorporated with several passive design features to give inherent passive means of negative reactivity insertion. The core nuclear performance based on a once-through equilibrium fuel cycle scenario shows that the core has an average breeding ratio of 0.67 and maximum discharge burnup of 47.3 MWD/kg. When comparing with conventional plutonium metallic fueled cores of the same power level, the present uranium metallic fueled core has a lower power density due to its increased physical core size. The negative sodium void reactivity over the core shows a beneficial potential to assure inherent safety characteristics. The transition from the uranium startup to equilibrium cycle is feasible without any design change. Core nuclear performance characteristics in the present core design are attributed to the specific design requirements of enrichment restriction and fuel cycle length.

  18. Fracture Surface Fractal Characteristics of Alkali-Slag Concrete under Freeze-Thaw Cycles

    Directory of Open Access Journals (Sweden)

    Wantong Cai

    2017-01-01

    Full Text Available Fractal theory is introduced in fracture surface research of alkali-slag concrete (ASC under freeze-thaw cycles; crack distribution of ASC fracture surface and freeze-thaw damage zone were calculated. Through fractal analysis of ASC sample fracture surfaces, relevance between section fractal dimension and fracture toughness and relationship between material composition and section fractal dimension are clarified. Results show that the specimen’s cracks before freeze-thaw extend along force direction gently, and there are more twists and turns after freezing and thawing; the fractal dimension D also grows from 1.10 to 1.33. SEM internal microcracks’ D of ASC internal microstructure after freezing and thawing is 1.37; 0 to 300 times ASC fractal dimension under freezing and thawing is between 2.10 and 2.23; with freeze-thaw times increasing, ASC fracture toughness decreases and fractal dimension increases, the fractal dimension and fracture toughness have a good linear relationship, and the fractal dimension can reflect the toughening effect of ASC. It is very feasible to evaluate ASC fracture behaviour under freezing and thawing with the fractal theory. Fractal dimension generally increases with activator solution-slag (A/S for short or slag content. The greater the amount of A/S or slag content, the lower the dimension.

  19. Phenological cycle and physicochemical characteristics of avocado cultivars in subtropical conditions

    Directory of Open Access Journals (Sweden)

    Geovanna Cristina Zaro

    2017-05-01

    Full Text Available Avocado has a great potential as a commercial crop in southern Brazil, for its high productivity, rusticity, and multiple uses. Its high oil content can be explored for biodiesel production with advantages over other crops. This study comprised six avocado cultivars-Geada, Fortuna, Fuerte, Margarida, Primavera and Quintal-belonging to the Agronomic Institute of Paraná (IAPAR collection, from Londrina, Brazil (23° 23′ S, 50° 11′ W. Analysis of fruit growth (length and diameter allowed the classification of the cultivars into groups showing early, midseason, and late maturation, which were harvested in March/April, May/June, and July/August, respectively. The fruits were analyzed to assess their pulp, peel, and seed proportions, and their levels of oil (pulp and starch (seed. Results showed these six cultivars are good alternatives for oil extraction. Fuerte stands out as the most adequate for biodiesel production from pulp and seed due to its higher yield of oil and starch. The fruit cycle diversity of these cultivars might allow combining them for prolonged fruit production, both for fresh fruit marketing and biodiesel supply, as well as possibly using fruit pulp for oil extraction and seed starch for alcohol production.

  20. Variation in subsurface thermal characteristics of microrefuges used by range core and peripheral populations of the American pika (Ochotona princeps).

    Science.gov (United States)

    Rodhouse, Thomas J; Hovland, Matthew; Jeffress, Mackenzie R

    2017-03-01

    Microrefuges provide microclimates decoupled from inhospitable regional climate regimes that enable range-peripheral populations to persist and are important to cold-adapted species in an era of accelerated climate change. However, identifying and describing the thermal characteristics of microrefuge habitats is challenging, particularly for mobile organisms in cryptic, patchy habitats. We examined variation in subsurface thermal conditions of microrefuge habitats among different rock substrate types used by the American pika (Ochotona princeps), a climate-sensitive, rock-dwelling Lagomorph. We compared subsurface temperatures in talus and lava substrates in pika survey sites in two US national park units; one park study area on the range periphery and the other in the range core. We deployed paired sensors to examine within-site temperature variation. We hypothesized that subsurface temperatures within occupied sites and structurally complex substrates would be cooler in summer and warmer in winter than unoccupied and less complex sites. Although within-site variability was high, with correlations between paired sensors as low as 47%, we found compelling evidence that pikas occupy microrefuge habitats where subsurface conditions provide more thermal stability than in unoccupied microhabitats. The percentage of days in which microhabitat temperatures were between -2.5 and 25.5°C was significantly higher in occupied sites. Interestingly, thermal conditions were substantially more stable (p < .05) in the lava substrate type identified to be preferentially used by pikas (pahoehoe vs. a'a) in a previous study. Our study and others suggest that thermal stability appears to be the defining characteristic of subsurface microrefuges used by American pikas and is a likely explanation for enigmatic population persistence at the range periphery. Our study exemplifies an integrated approach for studying complex microhabitat conditions, paired with site use surveys and

  1. Geological factors affecting the chemical characteristics of the thermal waters of the carbonate karstified aquifers of Northern Vietnam

    Directory of Open Access Journals (Sweden)

    C. Drogue

    2000-01-01

    Full Text Available In northern Vietnam, exposed carbonate rock formations cover an area of more than 50,000 km2 .Their accumulated thickness from the Cambrian to the Triassic is in some places as much as 3000 m. Numerous thermal waters (springs and wells occur in these strongly karstified carbonate massifs. This is the result of significant ancient and present orogenic activity, as the region demonstrates by its strong seismic activity. These karstic formations are water-bearing and strongly recharged by rainfall of between 1600 mm and 2000 mm per year in 90% of the area concerned. In view of the average annual air temperatures (17°C-25°C according to the region, 23 sample springs or wells were chosen with water temperatures of between 29°C and 68°C. Hydrochemical characteristics of these thermal waters emerging in different carbonate-rock units were examined by chemical analyses of major ions. In this large region, thermal waters are divided into four hydrochemical types: the Na-Cl type resulting from the intrusion of sea water for distances of up to several kilometres inland and depths of 1000 m, the Ca-SO4 type, probably resulting from the leaching of deposits of metallic sulphides that are widely distributed in these carbonate-rock units, and finally the Ca-HCO3 and Mg-HCO3 types which are chemically similar to fresh karstic waters in limestones and dolostones. The occurrence of these thermal groundwaters as well as their chemical characteristics seem to indicate the existence of large-scale deepseated groundwater flow systems in the karstic aquifers. Keywords: Vietnam; thermal waters; karst; hydrochemistry

  2. Effect of dynamic and thermal prehistory on aerodynamic characteristics and heat transfer behind a sudden expansion in a round tube

    Science.gov (United States)

    Terekhov, V. I.; Bogatko, T. V.

    2017-03-01

    The results of a numerical study of the influence of the thicknesses of dynamic and thermal boundary layers on turbulent separation and heat transfer in a tube with sudden expansion are presented. The first part of this work studies the influence of the thickness of the dynamic boundary layer, which was varied by changing the length of the stabilization area within the maximal extent possible: from zero to half of the tube diameter. In the second part of the study, the flow before separation was hydrodynamically stabilized and the thermal layer before the expansion could simultaneously change its thickness from 0 to D1/2. The Reynolds number was varied in the range of {Re}_{{{{D}}1 }} = 6.7 \\cdot 103 {{to}} 1.33 \\cdot 105, and the degree of tube expansion remained constant at ER = ( D 2/ D 1)2 = 1.78. A significant effect of the thickness of the separated boundary layer on both dynamic and thermal characteristics of the flow is shown. In particular, it was found out that with an increase in the thickness of the boundary layer the recirculation zone increases and the maximal Nusselt number decreases. It was determined that the growth of the heat layer thickness does not affect the hydrodynamic characteristics of the flow after separation but does lead to a reduction of heat transfer intensity in the separation area and removal of the coordinates of maximal heat transfer from the point of tube expansion. The generalizing dependence for the maximal Nusselt number at various thermal layer thicknesses is given. Comparison with experimental data confirmed the main trends in the behavior of heat and mass transfer processes in separated flows behind a step with different thermal prehistories.

  3. Life Cycle Assessment of Thermal Treatment Technologies. An environmental and financial systems analysis of gasification, incineration and landfilling of waste

    Energy Technology Data Exchange (ETDEWEB)

    Assefa, Getachew; Eriksson, Ola [Royal Inst. of Tech., Stockholm (Sweden). Industrial Ecology; Jaeraas, Sven; Kusar, Henrik [Royal Inst. of Tech., Stockholm (Sweden). Chemical Technology

    2003-05-01

    A technology which is currently developed by researchers at KTH is catalytic combustion. which is one component of a gasification system. Instead of performing the combustion in the gas turbine by a flame, a catalyst is used. When the development of a new technology (as catalytic combustion) reaches a certain step where it is possible to quantify material-, energy- and capital flows, the prerequisites for performing a systems analysis is at hand. The systems analysis can be used to expand the know-how about the potential advantages of the catalytic combustion technology by highlighting its function as a component of a larger system. In this way it may be possible to point out weak points which have to be investigated more, but also strong points to emphasise the importance of further development. The aim of this project was to assess the energy turnover as well as the potential environmental impacts and economic costs of thermal treatment technologies in general and catalytic combustion in particular. By using a holistic assessment of the advantages and disadvantages of catalytic combustion of waste it was possible to identify the strengths and weaknesses of the technology under different conditions. Following different treatment scenarios have been studied: (1) Gasification with catalytic combustion, (2) Gasification with flame combustion, (3) Incineration with energy recovery and (4) Landfilling with gas collection. In the study compensatory district heating is produced by combustion. of biofuel. The power used for running the processes in the scenarios is supplied by the waste-to-energy technologies themselves while compensatory power is assumed to be produced. from natural gas. The emissions from the system studied were classified and characterised using methodology from Life Cycle Assessment into the following environmental impact categories: Global Warming Potential, Acidification Potential, Eutrophication Potential and finally Formation of Photochemical

  4. A temperature control method for shortening thermal cycling time to achieve rapid polymerase chain reaction (PCR) in a disposable polymer microfluidic device

    DEFF Research Database (Denmark)

    Bu, Minqiang; Perch-Nielsen, Ivan R.; Sørensen, Karen Skotte

    2013-01-01

    We present a temperature control method capable of effectively shortening the thermal cycling time of polymerase chain reaction (PCR) in a disposable polymer microfluidic device with an external heater and a temperature sensor. The method employs optimized temperature overshooting and undershooting...... steps to achieve a rapid ramping between the temperature steps for DNA denaturation, annealing and extension. The temperature dynamics within the microfluidic PCR chamber was characterized and the overshooting and undershooting parameters were optimized using the temperature-dependent fluorescence...

  5. A novel temperature control method for shortening thermal cycling time to achieve rapid polymerase chain reaction (PCR) in a disposable polymer microfluidic device

    DEFF Research Database (Denmark)

    Bu, Minqiang; R. Perch-Nielsen, Ivan; Sørensen, Karen Skotte

    We present a new temperature control method capable of effectively shortening the thermal cycling time of polymerase chain reaction (PCR) in a disposable polymer microfluidic device with external heater and temperature sensor. The method employs optimized temperature overshooting and undershooting...... steps to achieve a rapid ramping between the temperature steps for DNA denaturation, annealing and extension. The temperature dynamics within the microfluidic PCR chamber was characterized and the overshooting and undershooting parameters were optimized using the temperature dependent fluorescence...

  6. A study about the contribution of the α-β phase transition of quartz to thermal cycle damage of a refractory used in fluidized catalytic cracking units

    Directory of Open Access Journals (Sweden)

    A. H. A. Pereira

    2014-09-01

    Full Text Available The deterioration of refractories used in fluidized catalytic cracking units (FCC-units is responsible for high costs of maintenance for the petrochemical industry. This is commonly associated with coke deposition during the production of light hydrocarbons. However, other mechanisms responsible for causing damage may also occur, such as the generation of cracks by expansive phase transition. The aim of the work herein was to study the contribution of the a-b phase transition of quartz particles to the deterioration of a commercial aluminosilicate refractory used in a riser by the means of slow thermal cycles. Such damage may occur if the working temperature of the equipment fluctuates around the a-b transition temperature (573 °C. The current study considered the material with and without coke impregnation to evaluate the combined effect of coke presence and phase transition. To evaluate the damage, it was used the Young's modulus as a function of temperature by applying the Impulse Excitation Technique under controlled atmosphere. An equipment recently developed by the authors research group was applied. Specimens were prepared and submitted to slow thermal cycles of temperatures up to 500 °C and up to 700 °C, with a heating rate of 2 °C/min. Part of the specimens was previously impregnated with coke by a reactor using propen. To complete the evaluation, characterization by X-ray diffraction, as well as by dilatometry and scanning electron microscopy were performed. The findings of this study showed that the presence of quartz particles determine the thermo-mechanical behaviour of the material, as well as the thermocycling damage resistance. In spite of the fact that the a-b phase transition stiffens the material during the heating stage, it increases the damage by slow thermal cycling. The coke impregnation increases the resistance to slow thermal cycles, however it decreases the resistance to the damage evolution.

  7. Experimental Investigation on the Thermal Mixing Characteristics of the Wire Wrapped 37 Rods Using a Laser Induced Fluorescence Technique

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S.; Choi, H. S.; Choi, S. R.; Kim, H. M.; Bae, H.; Chang, S. K.; Euh, D. J.; Lee, H. Y. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    The Nuclear Power Committee has established the objectives of the construction and the operation of the 4th generation LMFBR (Liquid Metal Fast Breed Reactor). To meet these goals, one of the subjects which is performing the production of the experimental data and also is estimating the uncertainties of the results of the CFD analysis should be undertaken. In other words, it is important to evaluate the accuracy of the model and the thermal hydraulic analysis code used to evaluate the safety of the SFR reactor core and quantify uncertainty. For the preliminary test before the 127 pin model test, the test loop for the wire wrapped 37 pin fuel assembly (FIFFA, Flow Identification for Fast reactor Fuel Assembly) was constructed to establish measurement technique. The heat transfer associated with the flow exchange between rod bundles was related with the diffusion coefficient. To identify a mixing characteristics among rod bundles, the optical measurement technique was adopted. To visualize and quantify the mixing characteristics between each rod bundle, the laser induced fluorescence (LIF) technique is one of suitable measurement technique. The CFD-grade experimental results will contribute to provide the benchmark data for validating the CFD analysis. LIF technique is adopted to visualize and quantify the mixing characteristics between each rod bundle in this study. The mixing characteristics data of reactor flow distribution will be utilized to evaluate and to validate the thermal margin analysis of the SFR reactor.

  8. Effects of simultaneous climate change and geomorphic evolution on thermal characteristics of a shallow Alaskan lake

    Science.gov (United States)

    Griffiths, Jennifer R.; Schindler, Daniel E.; Balistrieri, Laurie S.; Ruggerone, Gregory T.

    2011-01-01

    We used a hydrodynamics model to assess the consequences of climate warming and contemporary geomorphic evolution for thermal conditions in a large, shallow Alaskan lake. We evaluated the effects of both known climate and landscape change, including rapid outlet erosion and migration of the principal inlet stream, over the past 50 yr as well as future scenarios of geomorphic restoration. Compared to effects of air temperature during the past 50 yr, lake thermal properties showed little sensitivity to substantial (~60%) loss of lake volume, as the lake maximum depth declined from 6 m to 4 m driven by outlet erosion. The direction and magnitude of future lake thermal responses will be driven largely by the extent of inlet stream migration when it occurs simultaneously with outlet erosion. Maintaining connectivity with inlet streams had substantial effects on buffering lake thermal responses to warming climate. Failing to account for changing rates and types of geomorphic processes under continuing climate change may misidentify the primary drivers of lake thermal responses and reduce our ability to understand the consequences for aquatic organisms.

  9. Characteristics of thermally reduced graphene oxide and applied for dye-sensitized solar cell counter electrode

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Ching-Yuan, E-mail: cyho@cycu.edu.tw [Department of Mechanical Engineering, Chung Yuan Christian University, Chung-Li, Taiwan (China); Department of Chemistry, Center for Nanotechnology and Institute of Biomedical Technology, Chung Yuan Christian University, Chung-Li, Taiwan (China); Wang, Hong-Wen [Department of Chemistry, Center for Nanotechnology and Institute of Biomedical Technology, Chung Yuan Christian University, Chung-Li, Taiwan (China); Department of Chemistry, Chung Yuan Christian University, Chung-Li, Taiwan (China)

    2015-12-01

    Graphical abstract: Experimental process: (1) graphite oxidized to graphene oxide; (2) thermal reduction from graphene oxide to graphene; (3) applying to DSSC counter electrode. - Highlights: • Intercalated defects were eliminated by increasing reduction temperature of GO. • High reduction temperature of tGP has lower resistance, high the electron lifetime. • Higher thermal reduction of GO proposes electrocatalytic properties. • DSSC using tGP{sub 250} as counter electrode has energy conversion efficiency of 3.4%. - Abstract: Graphene oxide (GO) was synthesized from a flake-type of graphite powder, which was then reduced to a few layers of graphene sheets using the thermal reduction method. The surface morphology, phase crystallization, and defect states of the reduced graphene were determined from an electron microscope equipped with an energy dispersion spectrometer, X-ray diffraction, Raman spectroscopy, and infrared spectra. After graphene formation, the intercalated defects that existed in the GO were removed, and it became crystalline by observing impurity changes and d-spacing. Dye-sensitized solar cells, using reduced graphene as the counter electrode, were fabricated to evaluate the electrolyte activity and charge transport performance. The electrochemical impedance spectra showed that increasing the thermal reduction temperature could achieve faster electron transport and longer electron lifetime, and result in an energy conversion efficiency of approximately 3.4%. Compared to the Pt counter electrode, the low cost of the thermal reduction method suggests that graphene will enjoy a wide range of potential applications in the field of electronic devices.

  10. Characteristics of Atmospheric Circulation and Hydrologic Cycle over the North Pacific on Sub-seasonal Timescale

    Science.gov (United States)

    Ren, X.

    2016-12-01

    The air-sea system over the North Pacific region has multi-scale processes. Among them, the sub-seasonal timescale process has attracted literature due to its close linkage with persistent cold event or heavy rainfall event over east Asia and North American. In this study, we focused on the atmospheric circulation and hydrologic cycle over the North Pacific on sub-seasonal timescale. The EOF results showed that, there are two dominant modes of latent heat fluxes (evaporation) anomaly over the North Pacific ocean region on sub-seasonal timescale. The first mode exhibits an above normal/below normal latent heat release along the East Asian coastal region between 10º-45ºN, and below normal/above one to the east side. The first modes propagates downstream like the wave-train. The second mode shows a see-saw pattern, with positive anomaly over the Kuroshio and its extending region and negative one over the Northeast Pacific. It is seen that the associated anomalies in integrated vapor transport (IVT) and precipitation exhibit opposite sign with the anomaly in evaporation: increased/decreased evaporation from the ocean to the air is linkage with decreased/increased IVT and precipitation locally. Additionally, for the second mode, the increased IVT extends to the northwest part of the North America. The precipitation along the North American northwest coast increase significantly. The influences of the first mode is mainly located over the northwest Pacific and fades to the east of the dateline. The driver of the first mode is the southeastward propagation of a wave train across Eurasian mid and high latitudes. The invasion of the wave train into the northwest Pacific contributes to the first mode of latent heat anomaly over the North Pacific ocean region. The driver of the second mode is the intensified/weakened Aleutian low. When the Aleutian low is intensified on sub-seasonal timescale, the increased wind speed and colder air temperature induce above

  11. Porosity influence of power generating equipment structural materials on its thermoelastic characteristics and thermal conductivity

    Science.gov (United States)

    Zarubin, V. S.; Sergeeva, E. S.

    2017-11-01

    This paper outlines simulation models that represent the quantitative interdependencies between the thermal conductivity and the thermoelastic properties of composites, on the one hand, and their porous structure and matrix properties, as well as the volume fraction of their reinforcing inclusions, on the other hand. As the reinforcing inclusions, randomly-oriented anisotropic single-wall carbon nanotubes (SWNT) are taken. The key means for constructing the simulation models are the self-matching method and the dual variational formulation of the thermal conductivity/thermoelasticity problem for a non-homogeneous solid body. With the simulation models presented below, it is possible to estimate the effect the nanocomposite porosity has on the thermoelastic properties and thermal conductivity of nanocomposites.

  12. Thermal Characteristics of ThermoBrachytherapy Surface Applicators (TBSA) for Treating Chestwall Recurrence

    Science.gov (United States)

    Arunachalam, K.; Maccarini, P. F.; Craciunescu, O. I.; Schlorff, J. L.; Stauffer, P. R.

    2010-01-01

    Purpose To study temperature and thermal dose distributions of ThermoBrachytherapy Surface Applicators (TBSA) developed for concurrent or sequential high dose rate (HDR) brachytherapy and microwave hyperthermia treatment of chest wall recurrence and other superficial disease. Methods A steady state thermodynamics model coupled with the fluid dynamics of water bolus and electromagnetic radiation of hyperthermia applicator is used to characterize the temperature distributions achievable with TBSA applicators in an elliptical phantom model of the human torso. Power deposited by 915 MHz conformal microwave array (CMA) applicators is used to assess the specific absorption rate (SAR) distributions of rectangular (500 cm2) and L-shaped (875 cm2) TBSA. The SAR distribution in tissue and fluid flow distribution inside the Dual-Input Dual-Output (DIDO) water bolus are coupled to solve the steady state temperature and thermal dose distributions of rectangular TBSA (R-TBSA) for superficial tumor targets extending 10–15 mm beneath the skin surface. Thermal simulations are carried out for a range of bolus inlet temperature (Tb=38–43°C), water flow rate (Qb=2–4 L/min) and tumor blood perfusion (ωb=2–5 kg/m3/s) to characterize their influence on thermal dosimetry. Results Steady state SAR patterns of R- and L-TBSA demonstrate the ability to produce conformal and localized power deposition inside tumor target sparing surrounding normal tissues and nearby critical organs. Acceptably low variation in tissue surface cooling and surface temperature homogeneity was observed for the new DIDO bolus at 2 L/min water flow rate. Temperature depth profiles and thermal dose volume histograms indicate bolus inlet temperature (Tb) to be the most influential factor on thermal dosimetry. A 42 °C water bolus was observed to be the optimal choice for superficial tumors extending 10–15 mm from the surface even under significant blood perfusion. Lower bolus temperature may be chosen to

  13. Thermal characteristics of thermobrachytherapy surface applicators for treating chest wall recurrence

    Science.gov (United States)

    Arunachalam, K.; Maccarini, P. F.; Craciunescu, O. I.; Schlorff, J. L.; Stauffer, P. R.

    2010-04-01

    The aim of this study was to investigate temperature and thermal dose distributions of thermobrachytherapy surface applicators (TBSAs) developed for concurrent or sequential high dose rate (HDR) brachytherapy and microwave hyperthermia treatment of chest wall recurrence and other superficial diseases. A steady-state thermodynamics model coupled with the fluid dynamics of a water bolus and electromagnetic radiation of the hyperthermia applicator is used to characterize the temperature distributions achievable with TBSAs in an elliptical phantom model of the human torso. Power deposited by 915 MHz conformal microwave array (CMA) applicators is used to assess the specific absorption rate (SAR) distributions of rectangular (500 cm2) and L-shaped (875 cm2) TBSAs. The SAR distribution in tissue and fluid flow distribution inside the dual-input dual-output (DIDO) water bolus are coupled to solve the steady-state temperature and thermal dose distributions of the rectangular TBSA (R-TBSA) for superficial tumor targets extending 10-15 mm beneath the skin surface. Thermal simulations are carried out for a range of bolus inlet temperature (Tb = 38-43 °C), water flow rate (Qb = 2-4 L min-1) and tumor blood perfusion (ωb = 2-5 kg m-3 s-1) to characterize their influence on thermal dosimetry. Steady-state SAR patterns of the R- and L-TBSA demonstrate the ability to produce conformal and localized power deposition inside the tumor target sparing surrounding normal tissues and nearby critical organs. Acceptably low variation in tissue surface cooling and surface temperature homogeneity was observed for the new DIDO bolus at a 2 L min-1 water flow rate. Temperature depth profiles and thermal dose volume histograms indicate bolus inlet temperature (Tb) to be the most influential factor on thermal dosimetry. A 42 °C water bolus was observed to be the optimal choice for superficial tumors extending 10-15 mm from the surface even under significant blood perfusion. Lower bolus

  14. Changes in Acylglycerols composition, quality characteristics and in vivo effects of dietary pumpkin seed oil upon thermal oxidation

    Science.gov (United States)

    Zeb, Alam; Ahmad, Sultan

    2017-07-01

    This study was aimed to determine the acylglycerols composition, quality characteristics and protective role of dietary pumpkin seed oil in rabbits. Pumpkin seed oil was thermally oxidized and analyzed for quality characteristics and acylglycerols composition using reversed phase high performance liquid chromatography with diode array detection (HPLC-DAD). Oxidized and un-oxidized oil samples were fed to the rabbits in different doses for two weeks. The changes in the serum biochemistry, hematology, and liver histology were studied. The levels of quality parameters such peroxide value (PV), anisidine value (AV), total phenolic contents (TPC), thiobarbituric acid reactive substances (TBARS), conjugated dienes (CD) and conjugated trienes (CT) significantly increased with thermal treatment. HPLC analyses revealed ten individual triacylglycerols (TAGs), total di-acylglycerols (DAGs), mono-acylglycerols (MAGs), and total oxidized TAGs. Trilinolein (LLL), 1-oleoyl-2,3-dilinolinoyl glycerol (OLL), triolein (OOO) and 1,2-distearoyl-3-palmitoyl glycerol (SSP) were present in higher amounts and decreased with thermal treatment. Animal's studies showed that oxidized oils decreased the whole body weight, which was ameliorated by the co-administration of un-oxidized oils. The levels of serum biochemical parameters were improved by co-administration of pumpkin seed oils. There were no significant effects of both oxidized and un-oxidized pumpkin seed oil on the hematological and histological parameters of rabbits. In conclusion, nutritionally important triacylglycerols were present in pumpkin seed oil with protective role against the toxicity of its corresponding oxidized oils.

  15. Changes in Acylglycerols Composition, Quality Characteristics and In vivo Effects of Dietary Pumpkin Seed Oil upon Thermal Oxidation

    Directory of Open Access Journals (Sweden)

    Alam Zeb

    2017-07-01

    Full Text Available This study was aimed to determine the acylglycerols composition, quality characteristics, and protective role of dietary pumpkin seed oil (PSO in rabbits. PSO was thermally oxidized and analyzed for quality characteristics and acylglycerols composition using reversed phase high performance liquid chromatography with diode array detection (HPLC-DAD. Oxidized and un-oxidized oil samples were fed to the rabbits in different doses for 2 weeks. The changes in the serum biochemistry, hematology, and liver histology were studied. The levels of quality parameters such peroxide value (PV, anisidine value (AV, total phenolic contents (TPC, thiobarbituric acid reactive substances (TBARS, conjugated dienes (CD and conjugated trienes (CT significantly increased with thermal treatment. HPLC analyses revealed 10 individual triacylglycerols (TAGs, total di-acylglycerols (DAGs, mono-acylglycerols (MAGs, and total oxidized TAGs. Trilinolein (LLL, 1-oleoyl-2,3-dilinolinoyl glycerol (OLL, triolein (OOO and 1,2-distearoyl-3-palmitoyl glycerol (SSP were present in higher amounts and decreased with thermal treatment. Animal's studies showed that oxidized oils decreased the whole body weight, which was ameliorated by the co-administration of un-oxidized oils. The levels of serum biochemical parameters were improved by co-administration of pumpkin seed oils. There were no significant effects of both oxidized and un-oxidized PSO on the hematological and histological parameters of rabbits. In conclusion, nutritionally important triacylglycerols were present in PSO with protective role against the toxicity of its corresponding oxidized oils.

  16. Changes in Acylglycerols Composition, Quality Characteristics and In vivo Effects of Dietary Pumpkin Seed Oil upon Thermal Oxidation.

    Science.gov (United States)

    Zeb, Alam; Ahmad, Sultan

    2017-01-01

    This study was aimed to determine the acylglycerols composition, quality characteristics, and protective role of dietary pumpkin seed oil (PSO) in rabbits. PSO was thermally oxidized and analyzed for quality characteristics and acylglycerols composition using reversed phase high performance liquid chromatography with diode array detection (HPLC-DAD). Oxidized and un-oxidized oil samples were fed to the rabbits in different doses for 2 weeks. The changes in the serum biochemistry, hematology, and liver histology were studied. The levels of quality parameters such peroxide value (PV), anisidine value (AV), total phenolic contents (TPC), thiobarbituric acid reactive substances (TBARS), conjugated dienes (CD) and conjugated trienes (CT) significantly increased with thermal treatment. HPLC analyses revealed 10 individual triacylglycerols (TAGs), total di-acylglycerols (DAGs), mono-acylglycerols (MAGs), and total oxidized TAGs. Trilinolein (LLL), 1-oleoyl-2,3-dilinolinoyl glycerol (OLL), triolein (OOO) and 1,2-distearoyl-3-palmitoyl glycerol (SSP) were present in higher amounts and decreased with thermal treatment. Animal's studies showed that oxidized oils decreased the whole body weight, which was ameliorated by the co-administration of un-oxidized oils. The levels of serum biochemical parameters were improved by co-administration of pumpkin seed oils. There were no significant effects of both oxidized and un-oxidized PSO on the hematological and histological parameters of rabbits. In conclusion, nutritionally important triacylglycerols were present in PSO with protective role against the toxicity of its corresponding oxidized oils.

  17. Assessment of endometrial and ovarian characteristics using three dimensional power Doppler ultrasound to predict response in frozen embryo transfer cycles.

    Science.gov (United States)

    Zácková, Tamara; Järvelä, Ilkka Y; Tapanainen, Juha S; Feyereisl, Jaroslav

    2009-12-25

    To evaluate whether endometrial or ovarian parameters as measured using 3D power Doppler ultrasound would predict the outcome in frozen embryo transfer (FET) cycles. Thirty women with no known gynecological pathology undergoing FET were recruited. The FET was carried out in the natural menstrual cycle 3-4 days after the first positive LH test result. Blood samples for hormonal analysis were collected, and three-dimensional (3D) ultrasonographic examination was performed on the day of the FET and repeated with analysis of the total hCG one week later. The demographic, clinical, and embryological characteristics were similar between the pregnant (15/30) and nonpregnant groups (15/30). There were no differences between the groups in endometrial/subendometrial thickness, volume, or vascularization index (VI). The endometrial triple-line pattern was more often present in the pregnant group on the day of the FET (93.3% vs. 40.0%, 95% CI 25.5-81.2%). No differences in the ovaries were observed on the day of the FET. At the second visit, the triple-line pattern was still more often present in those patients who had conceived (91.7% vs. 42.9%, 95% CI 18.5-79.1%), and their corpus luteum was more active as judged by the rise in 17-hydroxyprogesterone and estradiol levels. No differences were observed in the dominant ovarian vasculature. According to our results, measurement of power Doppler indices using 3D ultrasound on the day of the FET does not provide any additional information concerning the outcome of the cycle. The existence of the triple-line pattern on the day of the FET seems to be a prognostic sign of a prosperous outcome after FET. The dominant ovary in the pregnant group seems to be already activated one week after the FET.

  18. Characteristics of the bological cycle of Lutzomyia evandroi Costa Lima & Antunes, 1936 (Diptera: Psychodidae under experimental conditions

    Directory of Open Access Journals (Sweden)

    Ximenes Maria de Fátima Freire de Melo

    2001-01-01

    Full Text Available Lutzomyia evandroi Costa Lima and Antunes, 1936 is found in Rio Grande do Norte, northeastern Brazil, in areas of visceral and mucocutaneous leishmaniasis and follows the same geographic distribution of L. longipalpis. The biological cycle, oviposition, morphological and behavioral characteristics of the species were studied under experimental conditions. The average number of eggs per wild caught female varied from 21 to 50 eggs along the year, with a peak occurring between January and March and another in August, with oviposition lasting for 4 to 12 days. The mean larval phase was 24 days. Ovipositing rates were influenced by rainfall and temperature indexes, with an increase of eggs per oviposition at the beginning and at the end of the rainy season, and a decrease at the peak of the rainy season.

  19. Severity of urban cycling injuries and the relationship with personal, trip, route and crash characteristics: analyses using four severity metrics.

    Science.gov (United States)

    Cripton, Peter A; Shen, Hui; Brubacher, Jeff R; Chipman, Mary; Friedman, Steven M; Harris, M Anne; Winters, Meghan; Reynolds, Conor C O; Cusimano, Michael D; Babul, Shelina; Teschke, Kay

    2015-01-05

    To examine the relationship between cycling injury severity and personal, trip, route and crash characteristics. Data from a previous study of injury risk, conducted in Toronto and Vancouver, Canada, were used to classify injury severity using four metrics: (1) did not continue trip by bike; (2) transported to hospital by ambulance; (3) admitted to hospital; and (4) Canadian Triage and Acuity Scale (CTAS). Multiple logistic regression was used to examine associations with personal, trip, route and crash characteristics. Of 683 adults injured while cycling, 528 did not continue their trip by bike, 251 were transported by ambulance and 60 were admitted to hospital for further treatment. Treatment urgencies included 75 as CTAS=1 or 2 (most medically urgent), 284 as CTAS=3, and 320 as CTAS=4 or 5 (least medically urgent). Older age and collision with a motor vehicle were consistently associated with increased severity in all four metrics and statistically significant in three each (both variables with ambulance transport and CTAS; age with hospital admission; and motor vehicle collision with did not continue by bike). Other factors were consistently associated with more severe injuries, but statistically significant in one metric each: downhill grades; higher motor vehicle speeds; sidewalks (these significant for ambulance transport); multiuse paths and local streets (both significant for hospital admission). In two of Canada's largest cities, about one-third of the bicycle crashes were collisions with motor vehicles and the resulting injuries were more severe than in other crash circumstances, underscoring the importance of separating cyclists from motor vehicle traffic. Our results also suggest that bicycling injury severity and injury risk would be reduced on facilities that minimise slopes, have lower vehicle speeds, and that are designed for bicycling rather than shared with pedestrians. Published by the BMJ Publishing Group Limited. For permission to use (where

  20. Severity of urban cycling injuries and the relationship with personal, trip, route and crash characteristics: analyses using four severity metrics

    Science.gov (United States)

    Cripton, Peter A; Shen, Hui; Brubacher, Jeff R; Chipman, Mary; Friedman, Steven M; Harris, M Anne; Winters, Meghan; Reynolds, Conor C O; Cusimano, Michael D; Babul, Shelina; Teschke, Kay

    2015-01-01

    Objective To examine the relationship between cycling injury severity and personal, trip, route and crash characteristics. Methods Data from a previous study of injury risk, conducted in Toronto and Vancouver, Canada, were used to classify injury severity using four metrics: (1) did not continue trip by bike; (2) transported to hospital by ambulance; (3) admitted to hospital; and (4) Canadian Triage and Acuity Scale (CTAS). Multiple logistic regression was used to examine associations with personal, trip, route and crash characteristics. Results Of 683 adults injured while cycling, 528 did not continue their trip by bike, 251 were transported by ambulance and 60 were admitted to hospital for further treatment. Treatment urgencies included 75 as CTAS=1 or 2 (most medically urgent), 284 as CTAS=3, and 320 as CTAS=4 or 5 (least medically urgent). Older age and collision with a motor vehicle were consistently associated with increased severity in all four metrics and statistically significant in three each (both variables with ambulance transport and CTAS; age with hospital admission; and motor vehicle collision with did not continue by bike). Other factors were consistently associated with more severe injuries, but statistically significant in one metric each: downhill grades; higher motor vehicle speeds; sidewalks (these significant for ambulance transport); multiuse paths and local streets (both significant for hospital admission). Conclusions In two of Canada's largest cities, about one-third of the bicycle crashes were collisions with motor vehicles and the resulting injuries were more severe than in other crash circumstances, underscoring the importance of separating cyclists from motor vehicle traffic. Our results also suggest that bicycling injury severity and injury risk would be reduced on facilities that minimise slopes, have lower vehicle speeds, and that are designed for bicycling rather than shared with pedestrians. PMID:25564148