WorldWideScience

Sample records for operative temperature ramps

  1. Human subjects’ perception of indoor environment and their office work performance during exposures to moderate operative temperature ramps

    DEFF Research Database (Denmark)

    Kolarik, Jakub; Toftum, Jørn; Olesen, Bjarne W.

    2008-01-01

    sensation was also included. Subjects filled out questionnaires regarding perception of the environment and intensity of SBS symptoms. Subjects performed simulated office tasks (addition, text typing, proof reading, comprehension and reasoning). Results showed that all tested ramps were recognized....... A linear relation between perceived air quality and temperature (enthalpy) was found. No significant consistent effect of individual temperature ramps on office work performance was found. Increasing operative temperature appeared to slightly decrease speed of addition and text typing regardless the slope...... of perceived air quality. Increasing temperature may negatively influence speed of simple, repetitive tasks of mental work. The significant effect on complex tasks that require concentration, vigilance and logical thinking was not found....

  2. Human subjects’ perception of indoor environment and their office work performance during exposures to moderate operative temperature ramps

    DEFF Research Database (Denmark)

    Kolarik, Jakub; Toftum, Jørn; Olesen, Bjarne W.;

    2008-01-01

    sensation was also included. Subjects filled out questionnaires regarding perception of the environment and intensity of SBS symptoms. Subjects performed simulated office tasks (addition, text typing, proof reading, comprehension and reasoning). Results showed that all tested ramps were recognized...

  3. The Line Operations Safety Audit Program: Transitioning From Flight Operations to Maintenance and Ramp Operations

    Science.gov (United States)

    2011-09-01

    A Line Operations Safety Audit ( LOSA ) is a voluntary safety program that collects safety data during normal airline operations and was originally...maintenance and ramp operations. This report provides a review of the use of LOSA , discusses LOSA’s essential operating characteristics, lessons learned on...the flight deck, and describes the extension of LOSA to maintenance and ramp operations. The research team developed tools for airlines and

  4. Novel Surveillance Technologies for Airport Ramp Area Operations Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of the current research is to develop the concept, algorithms and software necessary for enabling a novel surveillance system for airports ramp areas....

  5. Wind-Friendly Flexible Ramping Product Design in Multi-Timescale Power System Operations

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Mingjian; Zhang, Jie; Wu, Hongyu; Hodge, Bri-Mathias

    2017-07-01

    With increasing wind power penetration in the electricity grid, system operators are recognizing the need for additional flexibility, and some are implementing new ramping products as a type of ancillary service. However, wind is generally thought of as causing the need for ramping services, not as being a potential source for the service. In this paper, a multi-timescale unit commitment and economic dispatch model is developed to consider the wind power ramping product (WPRP). An optimized swinging door algorithm with dynamic programming is applied to identify and forecast wind power ramps (WPRs). Designed as positive characteristics of WPRs, the WPRP is then integrated into the multi-timescale dispatch model that considers new objective functions, ramping capacity limits, active power limits, and flexible ramping requirements. Numerical simulations on the modified IEEE 118-bus system show the potential effectiveness of WPRP in increasing the economic efficiency of power system operations with high levels of wind power penetration. It is found that WPRP not only reduces the production cost by using less ramping reserves scheduled by conventional generators, but also possibly enhances the reliability of power system operations. Moreover, wind power forecasts play an important role in providing high-quality WPRP service.

  6. Elution parameters in constant-pressure, single-ramp temperature-programmed gas chromatography.

    Science.gov (United States)

    Blumberg, L M; Klee, M S

    2001-05-18

    The dependence of the degree of interaction of a solute with the stationary phase at the time of its elution from the column in temperature-programmed GC is best described by interaction level of the solute. The latter represents the fraction of a solute residing in the stationary phase relative to the total amount of the solute. A simple approach to the evaluation of interaction levels of eluting solutes in a single-ramp temperature program is proposed. In a single-ramp temperature program having no preceding temperature plateau, all solutes that elute at temperatures that are about 60 degrees C higher than the initial temperature of the heating ramp elute with nearly the same interaction levels that can be found as exp(-r), where r is dimensionless heating rate. A specially designed temperature plateau preceding the ramp causes all solutes eluting during the entire time of the ramp to elute with nearly the same interaction levels equal to exp(-r). A transformation of the interaction level of a solute into its retention factor or mobility factor (a fraction of a solute in a mobile phase in relation to the total amount of the solute) and vice versa is also described.

  7. Safety Enhancement Technologies for Airport Ramp Area Operations Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has been involved in developing advanced automation systems for improving the efficiency of air-traffic operations, reducing controller workload and enhancing...

  8. Impacts of ramping inflexibility of conventional generators on strategic operation of energy storage facilities

    DEFF Research Database (Denmark)

    Nasrolahpour, Ehsan; Kazempour, Jalal; Zareipour, Hamidreza

    2016-01-01

    This paper proposes an approach to assist a pricemaker merchant energy storage facility in making its optimal operation decisions. The facility operates in a pool-based electricity market, where the ramping capability of other resources is limited. Also, wind power resources exist in the system....... The merchant facility seeks to maximize its profit through strategic inter-temporal arbitrage decisions, when taking advantage of those ramp limitations. The market operator, on the other hand, aims at maximizing the social welfare under wind power generation uncertainty. Thus, a stochastic bi......-level optimization model is proposed, taking into account the interactions between the storage facility and the market operator, and the existing market opportunities for the storage facility. The proposed bilevel model is then transformed into a Mathematical Program with Equilibrium Constraints (MPEC) that can...

  9. Ramping turn-to-turn loss and magnetization loss of a No-Insulation (RE)Ba2Cu3Ox high temperature superconductor pancake coil

    Science.gov (United States)

    Wang, Y.; Song, H.; Yuan, W.; Jin, Z.; Hong, Z.

    2017-03-01

    This paper is to study ramping turn-to-turn loss and magnetization loss of a no-insulation (NI) high temperature superconductor (HTS) pancake coil wound with (RE)Ba2Cu3Ox (REBCO) conductors. For insulated (INS) HTS coils, a magnetization loss occurs on superconducting layers during a ramping operation. For the NI HTS coil, additional loss is generated by the "bypassing" current on the turn-to-turn metallic contacts, which is called "turn-to-turn loss" in this study. Therefore, the NI coil's ramping loss is much different from that of the INS coil, but few studies have been reported on this aspect. To analyze the ramping losses of NI coils, a numerical method is developed by coupling an equivalent circuit network model and a H-formulation finite element method model. The former model is to calculate NI coil's current distribution and turn-to-turn loss, and the latter model is to calculate the magnetization loss. A test NI pancake coil is wound with REBCO tapes and the reliability of this model is validated by experiments. Then the characteristics of the NI coil's ramping losses are studied using this coupling model. Results show that the turn-to-turn loss is much higher than the magnetization loss. The NI coil's total ramping loss is much higher than that of its insulated counterpart, which has to be considered carefully in the design and operation of NI applications. This paper also discusses the possibility to reduce NI coil's ramping loss by decreasing the ramping rate of power supply or increasing the coil's turn-to-turn resistivity.

  10. Enhancing Power System Operational Flexibility With Flexible Ramping Products: A Review

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qin; Hodge, Bri-Mathias

    2017-08-01

    With the increased variability and uncertainty of net load induced from high penetrations of renewable energy resources and more flexible interchange schedules, power systems are facing great operational challenges in maintaining balance. Among these, the scarcity of ramp capability is an important culprit of power balance violations and high scarcity prices. To address this issue, market-based flexible ramping products (FRPs) have been proposed in the industry to improve the availability of ramp capacity. This paper presents an in-depth review of the modeling and implementation of FRPs. The major motivation is that although FRPs are widely discussed in the literature, it is still unclear to many how they can be incorporated into a co-optimization framework that includes energy and ancillary services. The concept and a definition of power system operational flexibility as well as the needs for FRPs are introduced. The industrial practices of implementing FRPs under different market structures are presented. Market operation issues and future research topics are also discussed. This paper can provide researchers and power engineers with further insights into the state of the art, technical barriers, and potential directions for FRPs.

  11. Self-ordered nanopore arrays through hard anodization assisted by anode temperature ramp

    Science.gov (United States)

    Mohammadniaei, M.; Maleki, K.; Kashi, M. Almasi; Ramezani, A.; Mayamei, Y.

    2016-10-01

    In the present work, hard anodization assisted by anode temperature ramp was employed to fabricate self-ordered nanoporous alumina in the wide range of interpore distances (259-405 nm) in pure oxalic acid and mixture of oxalic and phosphoric acid solutions. Anode temperature ramp technique was employed to adjust the anodization current density to optimize the self-ordering of the nanopore arrays in the interpore range in which no ordered self-assembled hard anodized anodic aluminum oxide has reported. It is found that the certain ratios of oxalic and phosphoric acid solutions in this anodization technique increased self-ordering of the nanopores especially for anodization voltages over the 170 V by increasing alumina's viscous flow which could lead to decrease the overall current density of anodization, yet leveled up by anode temperature ramp. However, below 150 V anodization voltage, the ratio of interpore distance to the anodization voltage of the both anodization techniques was the same (~2 nm/V), while above this voltage, it increased to about 2.2 nm/V.

  12. Analysis of the Effects of a Flexible Ramping Ancillary Service Product on Power System Operations: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Krad, Ibrahim; Ibanez, Eduardo; Ela, Erik

    2015-10-19

    The recent increased interest in utilizing variable generation (VG) resources such as wind and solar in power systems has motivated investigations into new operating procedures. Although these resources provide desirable value to a system (e.g., no fuel costs or emissions), interconnecting them provides unique challenges. Their variable, non-controllable nature in particular requires significant attention, because it directly results in increased power system variability and uncertainty. One way to handle this is via new operating reserve schemes. Operating reserves provide upward and downward generation and ramping capacity to counteract uncertainty and variability prior to their realization. For instance, uncertainty and variability in real-time dispatch can be accounted for in the hour-ahead unit commitment. New operating reserve methodologies that specifically account for the increased variability and uncertainty caused by VG are currently being investigated and developed by academia and industry. This paper examines one method inspired by the new operating reserve product being proposed by the California Independent System Operator. The method is based on examining the potential ramping requirements at any given time and enforcing those requirements via a reserve demand curve in the market-clearing optimization as an additional ancillary service product.

  13. Unsteady magnetohydrodynamic free convection flow of a second grade fluid in a porous medium with ramped wall temperature.

    Science.gov (United States)

    Samiulhaq; Ahmad, Sohail; Vieru, Dumitru; Khan, Ilyas; Shafie, Sharidan

    2014-01-01

    Magnetic field influence on unsteady free convection flow of a second grade fluid near an infinite vertical flat plate with ramped wall temperature embedded in a porous medium is studied. It has been observed that magnitude of velocity as well as skin friction in case of ramped temperature is quite less than the isothermal temperature. Some special cases namely: (i) second grade fluid in the absence of magnetic field and porous medium and (ii) Newtonian fluid in the presence of magnetic field and porous medium, performing the same motion are obtained. Finally, the influence of various parameters is graphically shown.

  14. Unsteady Magnetohydrodynamic Free Convection Flow of a Second Grade Fluid in a Porous Medium with Ramped Wall Temperature

    Science.gov (United States)

    Samiulhaq; Ahmad, Sohail; Vieru, Dumitru; Khan, Ilyas; Shafie, Sharidan

    2014-01-01

    Magnetic field influence on unsteady free convection flow of a second grade fluid near an infinite vertical flat plate with ramped wall temperature embedded in a porous medium is studied. It has been observed that magnitude of velocity as well as skin friction in case of ramped temperature is quite less than the isothermal temperature. Some special cases namely: (i) second grade fluid in the absence of magnetic field and porous medium and (ii) Newtonian fluid in the presence of magnetic field and porous medium, performing the same motion are obtained. Finally, the influence of various parameters is graphically shown. PMID:24785147

  15. Analysis of the EDIPO Temperature Margin During Current Ramp-Up

    CERN Document Server

    Marinucci, C; Calvi, Marco; Marinucci, Claudio; Cau, Francesca; Bottura, Luca

    2010-01-01

    The European dipole (EDIPO), currently under construction, will provide background magnetic fields of up to 12.5 T for tests of ITER high-current superconducting cables. The EDIPO winding consists of 7 x 2 double layers of Nb3SN cable-in-conduit conductors with forced flow cooling of supercritical helium. The performance limits of EDIPO during current ramp-up are analyzed analysed with the CryoSoft suite of codes, recently integrated into a customizable and flexible environment for the analysis of thermal hydraulic and electrical transients in superconducting magnetic systems. The simultaneous analysis of the cryogenic system and all 14 double layers shows that under all charging conditions the EDIPO temperature margin remains sufficiently high.

  16. Deep repository for spent nuclear fuel. Facility description - Layout E. Spiral ramp with one operational area

    Energy Technology Data Exchange (ETDEWEB)

    Pettersson, Stig [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden); Forsgren, Ebbe [SwedPower AB, Stockholm (Sweden); Lange, Fritz [Lange Art AB, Stockholm (Sweden)

    2002-04-01

    below ground. The proposal is based on a hypothetical inland location with a rail link. The report describes a layout with a spiral ramp as access to the deposition area and with a single operational area above ground. The ramp will be used as a transport route for heavy and bulky transports. A shaft, that connects the operational area with the central area of the deposition area, is used for utility systems and for staff transports between the surface and the deposition area. It has been assumed that the deposition areas and the central area are on the same level. The appendix, describing a two level alternative, shows how the underground area could be arranged if the deposition area for regular operation were to be divided into two levels. The facility description concentrates on the situation during regular operation. It also describes the gradual expansion programme, including land requirements and connections to existing infrastructure. The report concludes with some perspective sketches, which give a vision of how the repository might look when ready for operation. This facility description is a translation of the Swedish SKB report R-02-18. It is important to note that the report gives an example of one possible design for the deep repository. Many issues concerning system design, functional solutions, layout and design ought to be investigated further before deciding on the final design.

  17. The value of improved wind power forecasting: Grid flexibility quantification, ramp capability analysis, and impacts of electricity market operation timescales

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qin; Wu, Hongyu; Florita, Anthony R.; Brancucci Martinez-Anido, Carlo; Hodge, Bri-Mathias

    2016-12-01

    The value of improving wind power forecasting accuracy at different electricity market operation timescales was analyzed by simulating the IEEE 118-bus test system as modified to emulate the generation mixes of the Midcontinent, California, and New England independent system operator balancing authority areas. The wind power forecasting improvement methodology and error analysis for the data set were elaborated. Production cost simulation was conducted on the three emulated systems with a total of 480 scenarios, considering the impacts of different generation technologies, wind penetration levels, and wind power forecasting improvement timescales. The static operational flexibility of the three systems was compared through the diversity of generation mix, the percentage of must-run baseload generators, as well as the available ramp rate and the minimum generation levels. The dynamic operational flexibility was evaluated by the real-time upward and downward ramp capacity. Simulation results show that the generation resource mix plays a crucial role in evaluating the value of improved wind power forecasting at different timescales. In addition, the changes in annual operational electricity generation costs were mostly influenced by the dominant resource in the system. Finally, the impacts of pumped-storage resources, generation ramp rates, and system minimum generation level requirements on the value of improved wind power forecasting were also analyzed.

  18. Unsteady Hydromagnetic Flow of a Heat Absorbing Dusty Fluid Past a Permeable Vertical Plate with Ramped Temperature

    Directory of Open Access Journals (Sweden)

    m Das

    2014-01-01

    Full Text Available The unsteady flow and heat transfer of a viscous incompressible, electrically conducting dusty fluid past vertical plate under the influence of a transverse magnetic field is studied with a view to examine the combined effects of suction, heat absorption and ramped wall temperature. The temperature of the wall is assumed to have a temporarily ramped profile which goes on increasing up to a certain time limit and then becomes constant. To investigate the effect of rampedness in wall temperature, the solution for the flow past an isothermal wall is also obtained. The governing partial differential equations are solved using Laplace transformation technique in which the inversion is obtained numerically using Matlab. To validate the results of numerical inversion a comparison between the numerical and analytical values of fluid and particle temperatures and Nusselt number is also presented. The effects of pertinent flow parameters affecting the flow and heat transfer are investigated with the help of graphs and tables. It is found that the increase in suction, heat absorption and particle concentration contribute in thinning the thermal and momentum boundary layers and the velocity and temperature for both the fluid and particle phases are higher in the case of a flow past an isothermal plate than that of a flow past a plate with ramped temperature.

  19. Wind Plant Ramping Behavior

    Energy Technology Data Exchange (ETDEWEB)

    Ela, E.; Kemper, J.

    2009-12-01

    With the increasing wind penetrations, utilities and operators (ISOs) are quickly trying to understand the impacts on system operations and planning. This report focuses on ramping imapcts within the Xcel service region.

  20. Effects of wall shear stress on unsteady MHD conjugate flow in a porous medium with ramped wall temperature.

    Directory of Open Access Journals (Sweden)

    Arshad Khan

    Full Text Available This study investigates the effects of an arbitrary wall shear stress on unsteady magnetohydrodynamic (MHD flow of a Newtonian fluid with conjugate effects of heat and mass transfer. The fluid is considered in a porous medium over a vertical plate with ramped temperature. The influence of thermal radiation in the energy equations is also considered. The coupled partial differential equations governing the flow are solved by using the Laplace transform technique. Exact solutions for velocity and temperature in case of both ramped and constant wall temperature as well as for concentration are obtained. It is found that velocity solutions are more general and can produce a huge number of exact solutions correlative to various fluid motions. Graphical results are provided for various embedded flow parameters and discussed in details.

  1. Tune and Chromaticity Control During Snapback and Ramp in 2015 LHC Operation

    CERN Document Server

    Schaumann, Michaela; Lamont, Mike; Solfaroli Camillocci, Matteo; Todesco, Ezio; Wenninger, Jorg

    2016-01-01

    Because of current redistribution on the superconducting cables, the harmonic components of the magnetic fields of the superconducting magnets in the Large Hadron Collider (LHC) show decay during the low field injection plateau. This results in tune and chromaticity variations for the beams. In the first few seconds of the ramp the original hysteresis state of the magnetic field is restored - the field snaps back. These fast dynamic field changes lead to strong tune and chromaticity excursions that, if not properly controlled, induce beam losses and potentially trigger a beam dump. A feed-forward system applies predicted corrections during the injection plateau and to the first part of the ramp to avoid violent changes of beam conditions. This paper discusses the snapback of tune and chromaticity as observed in 2015, as well as the control of beam parameters during the ramp. It also evaluates the quality of the applied feed-forward corrections and their reproducibility.

  2. Atomic Force Microscopy Thermally-Assisted Microsampling with Atmospheric Pressure Temperature Ramped Thermal Desorption/Ionization-Mass Spectrometry Analysis.

    Science.gov (United States)

    Hoffmann, William D; Kertesz, Vilmos; Srijanto, Bernadeta R; Van Berkel, Gary J

    2017-02-20

    The use of atomic force microscopy controlled nanothermal analysis probes for reproducible spatially resolved thermally assisted sampling of micrometer-sized areas (ca. 11 × 17 μm wide × 2.4 μm deep) from relatively low number-average molecular weight (Mn mass spectrometric analysis. The procedure and mechanism for material pickup, the sampling reproducibility and sampling size are discussed, and the oligomer distribution information available from slow temperature ramps versus ballistic temperature jumps is presented. For the Mn = 970 P2VP, the Mn and polydispersity index determined from the mass spectrometric data were in line with both the label values from the sample supplier and the value calculated from the simple infusion of a solution of polymer into the commercial atmospheric pressure chemical ionization source on this mass spectrometer. With a P2VP sample of higher Mn (Mn = 2070 and 2970), intact oligomers were still observed (as high as m/z 2793 corresponding to the 26-mer), but a significant abundance of thermolysis products were also observed. In addition, the capability for confident identification of the individual oligomers by slowly ramping the probe temperature and collecting data-dependent tandem mass spectra was also demonstrated. The material type limits to the current sampling and analysis approach as well as possible improvements in nanothermal analysis probe design to enable smaller area sampling and to enable controlled temperature ramps beyond the present upper limit of about 415 °C are also discussed.

  3. Amylose Phase Composition As Analyzed By FTIR In A Temperature Ramp: Influence Of Short Range Order On The Thermodynamic Properties

    Science.gov (United States)

    Bernazzani, Paul; Delmas, Genevieve

    1998-03-01

    Amylose, a major component of starch, is one of the most important biopolymers, being mainly associated with the pharmacological and food industries. Although widely studied, a complete control and understanding of the physical properties of amylose is still lacking. It is well known that structure and phase transition are important aspects of the functionality of biopolymers since they influence physical attributes such as appearance, digestibility, water holding capacity, etc. In the past, we have studied polyethylene phase composition by DSC in a very slow temperature (T) ramp (1K/h) and have demonstrated the presence and importance of short-range order on the polymer and its characteristics. In this study, we evaluated the phase composition of potato amylose and associated the thermodynamic properties with the presence of short-range order. Two methods were correlated, DSC (in a 1K/h T-ramp) and FTIR as a function of temperature, also in a 1K/h T-ramp. The effects of the various phases on thermodynamic properties such as gelation and enzyme or chemical resistance are discussed.

  4. GENERAL: Mode shift and stability control of a current mode controlled buck-boost converter operating in discontinuous conduction mode with ramp compensation

    Science.gov (United States)

    Bao, Bo-Cheng; Xu, Jian-Ping; Liu, Zhong

    2009-11-01

    By establishing the discrete iterative mapping model of a current mode controlled buck-boost converter, this paper studies the mechanism of mode shift and stability control of the buck-boost converter operating in discontinuous conduction mode with a ramp compensation current. With the bifurcation diagram, Lyapunov exponent spectrum, time-domain waveform and parameter space map, the performance of the buck-boost converter circuit utilizing a compensating ramp current has been analysed. The obtained results indicate that the system trajectory is weakly chaotic and strongly intermittent under discontinuous conduction mode. By using ramp compensation, the buck-boost converter can shift from discontinuous conduction mode to continuous conduction mode, and effectively operates in the stable period-one region.

  5. Mode shift and stability control of a current mode controlled buck-boost converter operating in discontinuous conduction mode with ramp compensation

    Institute of Scientific and Technical Information of China (English)

    Bao Bo-Cheng; Xu Jian-Ping; Liu Zhong

    2009-01-01

    By establishing the discrete iterative mapping model of a current mode controlled buck-boost converter, this paper studies the mechanism of mode shift and stability control of the buck-boost converter operating in discontinuous conduction mode with a ramp compensation current. With the bifurcation diagram, Lyapunov exponent spectrum, timedomain waveform and parameter space map, the performance of the buck-boost converter circuit utilizing a compensating ramp current has been analysed. The obtained results indicate that the system trajectory is weakly chaotic and strongly intermittent under discontinuous conduction mode. By using ramp compensation, the buck-boost converter can shift from discontinuous conduction mode to continuous conduction mode, and effectively operates in the stable period-one region.

  6. Occupant Responses and Office Work Performance in Environments with Moderately Drifting Operative Temperatures (RP-1269)

    DEFF Research Database (Denmark)

    Kolarik, Jakub; Toftum, Jørn; Olesen, Bjarne W.;

    2009-01-01

    Fifty-two experimental subjects (50% female) were seated in a climate chamber and exposed to operative temperature ramps with different slopes, directions, and durations during two related experiments. The first experiment covered a temperature range of 22°C–26.8°C (71.6°F–80.2°F) and subjects wo...

  7. RPC operation at high temperature

    CERN Document Server

    Aielli, G; Cardarelli, R; Di Ciaccio, A; Di Stante, L; Liberti, B; Paoloni, A; Pastori, E; Santonico, R

    2003-01-01

    The resistive electrodes of RPCs utilised in several current experiments (ATLAS, CMS, ALICE, BABAR and ARGO) are made of phenolic /melaminic polymers, with room temperature resistivities ranging from 10**1**0 Omega cm, for high rate operation in avalanche mode, to 5 multiplied by 10**1**1 Omega cm, for streamer mode operation at low rate. The resistivity has however a strong temperature dependence, decreasing exponentially with increasing temperature. We have tested several RPCs with different electrode resistivities in avalanche as well as in streamer mode operation. The behaviours of the operating current and of the counting rate have been studied at different temperatures. Long-term operation has also been studied at T = 45 degree C and 35 degree C, respectively, for high and low resistivity electrodes RPCs.

  8. Global Decoupling on the RHIC Ramp

    CERN Document Server

    Luo, Yun; Della Penna, Al; Fischer, Wolfram; Laster, Jonathan S; Marusic, Al; Pilat, Fulvia Caterina; Roser, Thomas; Trbojevic, Dejan

    2005-01-01

    The global betatron decoupling on the ramp is an important issue for the operation of the Relativistic Heavy Ion Collider (RHIC). In the polarized proton run, the betatron tunes are required to keep almost constant on the ramp to avoid spin resonance line crossing and the beam polarization loss. Some possible correction schemes on the ramp, like three-ramp correction, the coupling amplitude modulation and the coupling phase modulaxtion, have been found. The principles of these schemes are shortly reviewed and compared. Operational results of their applications on the RHIC ramps are given.

  9. Cable historical operating temperature estimator

    Energy Technology Data Exchange (ETDEWEB)

    Leon de, F.; St-Roch, P.; Beauregard, C. [Cyme International, St-Bruno, PQ (Canada)

    2006-07-01

    A tool designed to accurately determine the thermal age of underground cables was described. The cable historical operating temperature estimate (CHOTE) is a software application designed to identify which cables have exceeded their normal and emergency operating temperatures. CHOTE is also capable of predicting when cables are likely to reach their maximum design temperature in the future. The system operates by processing archived loading information from data acquisition systems in order to automatically analyze all the thermal sections of a system. Cables that exceed their emergency and normal temperatures for the longest amount of time are ranked first, and outputs display when and where the hot spots have occurred. CHOTE is also able to study the impact of the addition of new cables and to determine the remaining ampacity of cables installed in a given duct bank. It was concluded that the CHOTE system can help in the efficient management of cable repairs and installations. 28 refs., 7 figs.

  10. Natural Convection Heat and Mass Transfer Flow with Hall Current, Rotation, Radiation and Heat Absorption Past an Accelerated Moving Vertical Plate with Ramped Temperature

    Directory of Open Access Journals (Sweden)

    Gauri Shanker Seth

    2015-01-01

    Full Text Available An investigation of unsteady hydromagnetic natural convection heat and mass trans fer flow with Hall current of a viscous, incompressible, electrically conducting, heat absorbing and optically thin radiating fluid past an accelerated moving vertical plate through fluid saturated porous medium in a rotating environment is carried out when temperature of the plate has a temporarily ramped profile. The exact solutions of momentum, energy and concentration equations are obtained in closed form by Laplace transform technique. The expressions of skin friction, Nusselt number and Sherwood number are also derived. For both ramped temperature and isothermal plates, Hall current tends to accelerate primary and secondary fluid velocities whereas heat absorption and radiation have reverse effect on it. Rotation tends to retard primary fluid velocity whereas it has a reverse effect on secondary fluid velocity. Heat absorption and radiation have tendency to enhance rate of heat transfer at the plate.

  11. A novel method for delivering ramped cooling reveals rat behaviours at innocuous and noxious temperatures: A comparative study of human psychophysics and rat behaviour.

    Science.gov (United States)

    Dunham, James P; Hulse, Richard P; Donaldson, Lucy F

    2015-07-15

    Thermal sensory testing in rodents informs human pain research. There are important differences in the methodology for delivering thermal stimuli to humans and rodents. This is particularly true in cold pain research. These differences confound extrapolation and de-value nociceptive tests in rodents. We investigated cooling-induced behaviours in rats and psychophysical thresholds in humans using ramped cooling stimulation protocols. A Peltier device mounted upon force transducers simultaneously applied a ramped cooling stimulus whilst measuring contact with rat hind paw or human finger pad. Rat withdrawals and human detection, discomfort and pain thresholds were measured. Ramped cooling of a rat hind paw revealed two distinct responses: Brief paw removal followed by paw replacement, usually with more weight borne than prior to the removal (temperature inter-quartile range: 19.1 °C to 2.8 °C). Full withdrawal was evoked at colder temperatures (inter quartile range: -11.3 °C to -11.8 °C). The profile of human cool detection threshold and cold pain threshold were remarkably similar to that of the rat withdrawals behaviours. Previous rat cold evoked behaviours utilise static temperature stimuli. By utilising ramped cold stimuli this novel methodology better reflects thermal testing in patients. Brief paw removal in the rat is driven by non-nociceptive afferents, as is the perception of cooling in humans. This is in contrast to the nociceptor-driven withdrawal from colder temperatures. These findings have important implications for the interpretation of data generated in older cold pain models and consequently our understanding of cold perception and pain. Copyright © 2015. Published by Elsevier B.V.

  12. Never the twain shall meet? : Simulating sales & operations planning ramp-up dynamics in IT-enabled service supply chains

    NARCIS (Netherlands)

    Akkermans, Henk; Voss, C.; van Oers, Roeland; Zhu, Quan

    2016-01-01

    In IT-enabled service supply chains offering services through a mix of manual and automated activities, volume ramp-ups are notoriously difficult. Especially difficult is the attempt to effectively balance the inherently conflicting objectives of the functions Sales, who want to increase output as

  13. Dendritic flux instabilities in YB a2C u3O7 -x films: Effects of temperature and magnetic field ramp rate

    Science.gov (United States)

    Baruch-El, E.; Baziljevich, M.; Shapiro, B. Ya.; Johansen, T. H.; Shaulov, A.; Yeshurun, Y.

    2016-08-01

    Our recent success in triggering dendritic flux instabilities in YB a2C u3O7 -δ (YBCO) films by applying magnetic fields at ultrahigh rates is followed here by a detailed study of the effect as a function of the field ramp rate, B˙a, and temperature, T . We trace the borderline in the B˙a-T plane separating regions of smooth, gradual flux penetration and dendritic flux avalanches. In addition, we describe the changes in the dendritic morphology in the instability region as a result of changes in either B˙a or T . Our experimental results, showing a monotonic increase of the avalanche threshold field ramp rate with temperature, are discussed in the framework of existing theories. On the basis of these theories we also explain the high stability of YBCO to dendritic avalanches as compared to, e.g., Mg B2 , identifying the flux flow resistivity, rather than any of the thermal parameters, as the main parameter governing the film stability.

  14. GLOBAL DECOUPLING ON THE RHIC RAMP.

    Energy Technology Data Exchange (ETDEWEB)

    LUO, Y.; CAMERON, P.; DELLA PENNA, A.; FISCHER, W.; ET AL.

    2005-05-16

    The global betatron decoupling on the ramp is an important issue for the operation of the Relativistic Heavy Ion Collider (RHIC), especially in the RHIC polarized proton (pp) run. To avoid the major betatron and spin resonances on the ramp, the betatron tunes are constrained. And the rms value of the vertical closed orbit should be smaller than 0.5mm. Both require the global coupling on the ramp to be well corrected. Several ramp decoupling schemes were found and tested at RHIC, like N-turn map decoupling, three-ramp correction, coupling amplitude modulation, and coupling phase modulation. In this article, the principles of these methods are shortly reviewed and compared. Among them, coupling angle modulation is a robust and fast one. It has been applied to the global decoupling in the routine RHIC operation.

  15. Unsteady MHD Heat Transfer in Couette Flow of Water at 4°C in a Rotating System with Ramped Temperature via Finite Element Method

    Science.gov (United States)

    Reddy, G. J.; Raju, R. S.; Rao, J. A.; Gorla, R. S. R.

    2017-02-01

    An unsteady magnetohydromagnetic natural convection on the Couette flow of electrically conducting water at 4°C (Pr = 11.40) in a rotating system has been considered. A Finite Element Method (FEM) was employed to find the numerical solutions of the dimensionless governing coupled boundary layer partial differential equations. The primary velocity, secondary velocity and temperature of water at 4°C as well as shear stresses and rate of heat transfer have been obtained for both ramped temperature and isothermal plates. The results are independent of the mesh (grid) size and the present numerical solutions through the Finite Element Method (FEM) are in good agreement with the existing analytical solutions by the Laplace Transform Technique (LTT). These are shown in tabular and graphical forms.

  16. Unsteady MHD Heat Transfer in Couette Flow of Water at 4°C in a Rotating System with Ramped Temperature via Finite Element Method

    Directory of Open Access Journals (Sweden)

    Reddy G.J.

    2017-02-01

    Full Text Available An unsteady magnetohydromagnetic natural convection on the Couette flow of electrically conducting water at 4°C (Pr = 11.40 in a rotating system has been considered. A Finite Element Method (FEM was employed to find the numerical solutions of the dimensionless governing coupled boundary layer partial differential equations. The primary velocity, secondary velocity and temperature of water at 4°C as well as shear stresses and rate of heat transfer have been obtained for both ramped temperature and isothermal plates. The results are independent of the mesh (grid size and the present numerical solutions through the Finite Element Method (FEM are in good agreement with the existing analytical solutions by the Laplace Transform Technique (LTT. These are shown in tabular and graphical forms.

  17. Temperature buffer test. Dismantling operation

    Energy Technology Data Exchange (ETDEWEB)

    Aakesson, Mattias [Clay Technology AB, Lund (Sweden)

    2010-12-15

    The Temperature Buffer Test (TBT) is a joint project between SKB/ANDRA and supported by ENRESA (modelling) and DBE (instrumentation), which aims at improving the understanding and to model the thermo-hydro-mechanical behavior of buffers made of swelling clay submitted to high temperatures (over 100 deg C) during the water saturation process. The test has been carried out in a KBS-3 deposition hole at Aespoe HRL. It was installed during the spring of 2003. Two heaters (3 m long, 0.6 m diameter) and two buffer arrangements have been investigated: the lower heater was surrounded by bentonite in the usual way, whereas the upper heater was surrounded by a ring of sand. The test was dismantled and sampled during a period from the end of October 2009 to the end of April 2010, and this report describes this operation. Different types of samples have been obtained during this operation. A large number of diameter 50 mm bentonite cores have been taken for analysis of water content and density. Large pieces, so-called big sectors, have been taken for hydro-mechanical and chemical characterizations. Finally, there has been an interest to obtain different types of interface samples in which bentonite were in contact with sand, iron or concrete. One goal has been to investigate the retrievability of the upper heater, given the possibility to remove the surrounding sand shield, and a retrieval test has therefore been performed. The sand in the shield was first removed with an industrial vacuum cleaner after loosening the material through mechanical means (with hammer drill and core machine). A front loader was subsequently used for applying a sufficient lifting force to release the heater from the bentonite underneath. The experiment has been documented in different aspects: measurements of the coordinate (height or radius) of different interfaces (between bentonite blocks and between bentonite and sand); verification of sensor positions and retrieval of sensors for subsequent

  18. Temperature buffer test. Dismantling operation

    Energy Technology Data Exchange (ETDEWEB)

    Aakesson, Mattias [Clay Technology AB, Lund (Sweden)

    2010-12-15

    The Temperature Buffer Test (TBT) is a joint project between SKB/ANDRA and supported by ENRESA (modelling) and DBE (instrumentation), which aims at improving the understanding and to model the thermo-hydro-mechanical behavior of buffers made of swelling clay submitted to high temperatures (over 100 deg C) during the water saturation process. The test has been carried out in a KBS-3 deposition hole at Aespoe HRL. It was installed during the spring of 2003. Two heaters (3 m long, 0.6 m diameter) and two buffer arrangements have been investigated: the lower heater was surrounded by bentonite in the usual way, whereas the upper heater was surrounded by a ring of sand. The test was dismantled and sampled during a period from the end of October 2009 to the end of April 2010, and this report describes this operation. Different types of samples have been obtained during this operation. A large number of diameter 50 mm bentonite cores have been taken for analysis of water content and density. Large pieces, so-called big sectors, have been taken for hydro-mechanical and chemical characterizations. Finally, there has been an interest to obtain different types of interface samples in which bentonite were in contact with sand, iron or concrete. One goal has been to investigate the retrievability of the upper heater, given the possibility to remove the surrounding sand shield, and a retrieval test has therefore been performed. The sand in the shield was first removed with an industrial vacuum cleaner after loosening the material through mechanical means (with hammer drill and core machine). A front loader was subsequently used for applying a sufficient lifting force to release the heater from the bentonite underneath. The experiment has been documented in different aspects: measurements of the coordinate (height or radius) of different interfaces (between bentonite blocks and between bentonite and sand); verification of sensor positions and retrieval of sensors for subsequent

  19. Implementation Guideline for Maintenance Line Operations Safety Assessment (M-LOSA) and Ramp LOSA (R-LOSA) Programs

    Science.gov (United States)

    2012-08-01

    airlines and Maintenance Repair & Overhaul ( MROs ) communities. 53 Appendix A. Organizational Change Management – Stakeholder Strategy...Maintenance Line Operations Safety Audit MRO – Maintenance, Repair & Overhaul NOSS – Normal Operations Safety Survey QA – Quality Assurance RACI

  20. Effects of Ramped Wall Temperature on Unsteady Two-Dimensional Flow Past a Vertical Plate with Thermal Radiation and Chemical Reaction

    Directory of Open Access Journals (Sweden)

    V. Rajesh

    2014-08-01

    Full Text Available The interaction of free convection with thermal radiation of a viscous incompressible unsteady flow past a vertical plate with ramped wall temperature and mass diffusion is presented here, taking into account the homogeneous chemical reaction of first order. The fluid is gray, absorbing-emitting but non-scattering medium and the Rosseland approximation is used to describe the radiative flux in the energy equation. The dimensionless governing equations are solved using an implicit finite-difference method of the Crank-Nicolson type, which is stable and convergent. The velocity profiles are compared with the available theoretical solution and are found to be in good agreement. Numerical results for the velocity, the temperature, the concentration, the local and average skin friction, the Nusselt number and Sherwood number are shown graphically. This work has wide application in chemical and power engineering and also in the study of vertical air flow into the atmosphere. The present results can be applied to an important class of flows in which the driving force for the flow is provided by combination of the thermal and chemical species diffusion effects.

  1. Timing matters: the underappreciated role of temperature ramp rate for shape control and reproducibility of quantum dot synthesis

    KAUST Repository

    Baumgardner, William J.

    2012-01-01

    Understanding the coupled kinetic and thermodynamics factors governing colloidal nanocrystals nucleation and growth are critical factors in the predictable and reproducible synthesis of advanced nanomaterials. We show that the temporal temperature profile is decisive in tuning the particle shape from pseudo-spherical to monodisperse cubes. The shape of the nanocrystals was characterized by transmission electron microscopy and X-ray diffraction. We introduce a mechanism for the shape controlled synthesis in the context of temperature-dependent nucleation and growth and provide experimental evidence to support it. © 2013 The Royal Society of Chemistry.

  2. Lean Application to Manufacturing Ramp-Up

    DEFF Research Database (Denmark)

    Christensen, Irene; Rymaszewska, Anna

    2016-01-01

    product development process, that is, the ramp-up process, is a critical, early enabler of lean manufacturing. The manufacturing strategy literature conceptualizes a state of “leanness in operations,” which can consolidate both the concepts of lean and manufacturing ramp-up, providing a dual perspective......This article provides a theoretical overview of the concepts of lean and manufacturing ramp-up in an attempt to conceptualize the strategic areas in which lean philosophy and principles can be applied for continuous improvements. The application of lean principles during the final stage of a new....... Abstracting from the extant literature, the authors considered the competitiveness of manufacturing companies from two principal perspectives: the leanness of the ramp-up process and the new-value creation of quality managers. While much of the literature fails to acknowledge that the roots of lean actually...

  3. Thermal Operator Representation of Finite Temperature Graphs

    OpenAIRE

    Brandt, Fernando T.; Das, Ashok; Espinosa, Olivier; Frenkel, Josif; Perez, Silvana

    2005-01-01

    Using the mixed space representation (t,p) in the context of scalar field theories, we prove in a simple manner that the Feynman graphs at finite temperature are related to the corresponding zero temperature diagrams through a simple thermal operator, both in the imaginary time as well as in the real time formalisms. This result is generalized to the case when there is a nontrivial chemical potential present. Several interesting properties of the thermal operator are also discussed.

  4. Simple operated multipurpose temperature control cryostat

    Institute of Scientific and Technical Information of China (English)

    ABBAS T.A.; OMAR M.S.

    2007-01-01

    A suitable simple optical cryostat for optical, magneto-optical, electrical and thermo-electrical measurements was designed. It is suitable for use in a magnetic pool gap as narrow as less than 1 cm. Throughout a long period of time, the heat diffusion process of the cryostat can be easily operated at slow increase in sample temperature in a range 1.25 K/min at 200 K that will be reduced gradually to 0.66 K at room temperature. Liquid nitrogen was used to cool down the temperature. During the operation, the change in the measured energy gap of a semiconductor sample and other physical parameters resulting from the change of temperature can be corrected through the temperature coefficient of that parameter at the corresponding temperature.The cryostat was successfully used for all experiments mentioned above to measure the properties of a single crystal of GaP (Gallium Phosphate) semiconductor.

  5. Forward ramp in 3D

    Science.gov (United States)

    1997-01-01

    Mars Pathfinder's forward rover ramp can be seen successfully unfurled in this image, taken in stereo by the Imager for Mars Pathfinder (IMP) on Sol 3. 3D glasses are necessary to identify surface detail. This ramp was not used for the deployment of the microrover Sojourner, which occurred at the end of Sol 2. When this image was taken, Sojourner was still latched to one of the lander's petals, waiting for the command sequence that would execute its descent off of the lander's petal.The image helped Pathfinder scientists determine whether to deploy the rover using the forward or backward ramps and the nature of the first rover traverse. The metallic object at the lower left of the image is the lander's low-gain antenna. The square at the end of the ramp is one of the spacecraft's magnetic targets. Dust that accumulates on the magnetic targets will later be examined by Sojourner's Alpha Proton X-Ray Spectrometer instrument for chemical analysis. At right, a lander petal is visible.The IMP is a stereo imaging system with color capability provided by 24 selectable filters -- twelve filters per 'eye.' It stands 1.8 meters above the Martian surface, and has a resolution of two millimeters at a range of two meters.Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.Click below to see the left and right views individually. [figure removed for brevity, see original site] Left [figure removed for brevity, see original site] Right

  6. Electronics Demonstrated for Low- Temperature Operation

    Science.gov (United States)

    Patterson, Richard L.; Hammond, Ahmad; Gerber, Scott S.

    2000-01-01

    The operation of electronic systems at cryogenic temperatures is anticipated for many NASA spacecraft, such as planetary explorers and deep space probes. For example, an unheated interplanetary probe launched to explore the rings of Saturn would experience an average temperature near Saturn of about 183 C. Electronics capable of low-temperature operation in the harsh deep space environment also would help improve circuit performance, increase system efficiency, and reduce payload development and launch costs. An ongoing research and development program on low-temperature electronics at the NASA Glenn Research Center at Lewis Field is focusing on the design of efficient power systems that can survive and exploit the advantages of low-temperature environments. The targeted systems, which are mission driven, include converters, inverters, controls, digital circuits, and special-purpose circuits. Initial development efforts successfully demonstrated the low-temperature operation and cold-restart of several direct-current/direct-current (dc/dc) converters based on different types of circuit design, some with superconducting inductors. The table lists some of these dc/dc converters with their properties, and the photograph shows a high-voltage, high-power dc/dc converter designed for an ion propulsion system for low-temperature operation. The development efforts of advanced electronic systems and the supporting technologies for low-temperature operation are being carried out in-house and through collaboration with other Government agencies, industry, and academia. The Low Temperature Electronics Program supports missions and development programs at NASA s Jet Propulsion Laboratory and Goddard Space Flight Center. The developed technologies will be transferred to commercial end users for applications such as satellite infrared sensors and medical diagnostic equipment.

  7. Low temperature operation and exhaust emission

    Energy Technology Data Exchange (ETDEWEB)

    Laurikko, J.

    1987-01-01

    Ambient temperature has the greatest effect on the exhaust emissions of internal combustion engines during the initial cold star and before the engine is fully warmed-up. Fuel evaporation is poor in a cold engine and the fuel-air mixture must be made richer to ensure that the engine weill start and be driveable. However, the combustion of a rich fuel-air mixture is incomplete because of the lack of oxygen, and the exhaust gases will contain an excessive amount of carbon monoxide (CO). The formation of nitrogen oxides (NO/sub x/) in a combustion engine is tied to high temperatures and oxygen concentrations. The conditions in a non-warmed engine using a rich fuel-air mixture are unfavourable for the formation of NO/sub x/ and the emission of NO/sub x/ may even diminish with falling ambient temperature. When the engine has reached its normal operating temperature the exhaust emissions are usually independent of the ambient temperature if the engine is equipped with intake air preheating that is sufficiently powerful. The reduction efficiency of a catalytic converter mainly depends on its operation temperature. Continuous operation at low temperatures may cause rapid poisoning of the converter. At low temperatures, carbon and other particles that do not burn collect on the active surface of the converter reducing its effectiveness.

  8. Meniscal Ramp Lesions

    Science.gov (United States)

    Chahla, Jorge; Dean, Chase S.; Moatshe, Gilbert; Mitchell, Justin J.; Cram, Tyler R.; Yacuzzi, Carlos; LaPrade, Robert F.

    2016-01-01

    Meniscal ramp lesions are more frequently associated with anterior cruciate ligament (ACL) injuries than previously recognized. Some authors suggest that this entity results from disruption of the meniscotibial ligaments of the posterior horn of the medial meniscus, whereas others support the idea that it is created by a tear of the peripheral attachment of the posterior horn of the medial meniscus. Magnetic resonance imaging (MRI) scans have been reported to have a low sensitivity, and consequently, ramp lesions often go undiagnosed. Therefore, to rule out a ramp lesion, an arthroscopic evaluation with probing of the posterior horn of the medial meniscus should be performed. Several treatment options have been reported, including nonsurgical management, inside-out meniscal repair, or all-inside meniscal repair. In cases of isolated ramp lesions, a standard meniscal repair rehabilitation protocol should be followed. However, when a concomitant ACL reconstruction (ACLR) is performed, the rehabilitation should follow the designated ACLR postoperative protocol. The purpose of this article was to review the current literature regarding meniscal ramp lesions and summarize the pertinent anatomy, biomechanics, diagnostic strategies, recommended treatment options, and postoperative protocol. PMID:27504467

  9. Operator product expansion at finite temperature

    OpenAIRE

    Mallik, S.

    1997-01-01

    We extend an earlier, configuration space method to find the Wilson coefficients of operators appearing in the short distance expansion of thermal correlation functions of different quark bilinears. Considering all the different correlation functions, there arise, up to dimension four, two new operators, in addition to the two appearing already in the vacuum correlation functions. They would contribute substantially to the QCD sum rules, when the temperature is not too low.

  10. Current ramps in tokamaks: from present experiments to ITER scenarios

    NARCIS (Netherlands)

    Imbeaux, F.; Citrin, J.; Hobirk, J.; Hogeweij, G. M. D.; Kochl, F.; Leonov, V. M.; Miyamoto, S.; Nakamura, Y.; Parail, V.; Pereverzev, G.; Polevoi, A.; Voitsekhovitch, I.; Basiuk, V.; Budny, R.; Casper, T.; Fereira, J.; Fukuyama, A.; Garcia, J.; Gribov, Y. V.; Hayashi, N.; Honda, M.; Hutchinson, I. H.; Jackson, G.; Kavin, A. A.; Kessel, C. E.; Khayrutdinov, R. R.; Labate, C.; Litaudon, X.; Lomas, P. J.; Lonnroth, J.; Luce, T.; Lukash, V. E.; Mattei, M.; Mikkelsen, D.; Nunes, I.; Peysson, Y.; Politzer, P.; Schneider, M.; Sips, G.; Tardini, G.; Wolfe, S. M.; Zhogolev, V. E.

    2011-01-01

    In order to prepare adequate current ramp-up and ramp-down scenarios for ITER, present experiments from various tokamaks have been analysed by means of integrated modelling in view of determining relevant heat transport models for these operation phases. A set of empirical heat transport models for

  11. Meniscal Ramp Lesions

    OpenAIRE

    2016-01-01

    Meniscal ramp lesions are more frequently associated with anterior cruciate ligament (ACL) injuries than previously recognized. Some authors suggest that this entity results from disruption of the meniscotibial ligaments of the posterior horn of the medial meniscus, whereas others support the idea that it is created by a tear of the peripheral attachment of the posterior horn of the medial meniscus. Magnetic resonance imaging (MRI) scans have been reported to have a low sensitivity, ...

  12. Wide-Temperature-Range Integrated Operational Amplifier

    Science.gov (United States)

    Mojarradi, Mohammad; Levanas, Greg; Chen, Yuan; Kolawa, Elizabeth; Cozy, Raymond; Blalock, Benjamin; Greenwell, Robert; Terry, Stephen

    2007-01-01

    A document discusses a silicon-on-insulator (SOI) complementary metal oxide/semiconductor (CMOS) integrated- circuit operational amplifier to be replicated and incorporated into sensor and actuator systems of Mars-explorer robots. This amplifier is designed to function at a supply potential less than or equal to 5.5 V, at any temperature from -180 to +120 C. The design is implemented on a commercial radiation-hard SOI CMOS process rated for a supply potential of less than or equal to 3.6 V and temperatures from -55 to +110 C. The design incorporates several innovations to achieve this, the main ones being the following: NMOS transistor channel lengths below 1 m are generally not used because research showed that this change could reduce the adverse effect of hot carrier injection on the lifetimes of transistors at low temperatures. To enable the amplifier to withstand the 5.5-V supply potential, a circuit topology including cascade devices, clamping devices, and dynamic voltage biasing was adopted so that no individual transistor would be exposed to more than 3.6 V. To minimize undesired variations in performance over the temperature range, the transistors in the amplifier are biased by circuitry that maintains a constant inversion coefficient over the temperature range.

  13. Heat and Mass Transfer Effects on Unsteady MHD Natural Convection Flow of a Chemically Reactive and Radiating Fluid through a Porous Medium Past a Moving Vertical Plate with Arbitrary Ramped Temperature

    Directory of Open Access Journals (Sweden)

    Gauri Shanker Seth

    2016-01-01

    Full Text Available Investigation of unsteady hydromagnetic natural convection flow with heat and mass transfer of a viscous, incompressible, electrically conducting, chemically reactive and optically thin radiating fluid past an exponentially accelerated moving vertical plate with arbitrary ramped temperature embedded in a fluid saturated porous medium is carried out. Exact solutions of momentum, energy and concentration equations are obtained in closed form by Laplace transform technique. The expressions for the shear stress, rate of heat transfer and rate of mass transfer at the plate for both ramped temperature and isothermal plates are derived. The numerical values of fluid velocity, fluid temperature and species concentration are displayed graphically whereas those of shear stress, rate of heat transfer and rate of mass transfer at the plate are presented in tabular form for various values of pertinent flow parameters. It is found that, for isothermal plate, the fluid temperature approaches steady state when t  1.5 . Consequently, the rate of heat transfer at isothermal plate approaches steady state when t  1.5 .

  14. 33 CFR 159.119 - Operability test; temperature range.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Operability test; temperature range. 159.119 Section 159.119 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND... Operability test; temperature range. The device must operate in an ambient temperature of 5 °C with...

  15. Wind Power Ramping Product for Increasing Power System Flexibility

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Mingjian; Zhang, Jie; Wu, Hongyu; Hodge, Bri-Mathias; Ke, Deping; Sun, Yuanzhang

    2016-05-05

    With increasing penetrations of wind power, system operators are concerned about a potential lack of system flexibility and ramping capacity in real-time dispatch stages. In this paper, a modified dispatch formulation is proposed considering the wind power ramping product (WPRP). A swinging door algorithm (SDA) and dynamic programming are combined and used to detect WPRPs in the next scheduling periods. The detected WPRPs are included in the unit commitment (UC) formulation considering ramping capacity limits, active power limits, and flexible ramping requirements. The modified formulation is solved by mixed integer linear programming. Numerical simulations on a modified PJM 5-bus System show the effectiveness of the model considering WPRP, which not only reduces the production cost but also does not affect the generation schedules of thermal units.

  16. A survey on wind power ramp forecasting.

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, C.; Gama, J.; Matias, L.; Botterud, A.; Wang, J. (Decision and Information Sciences); (INESC Porto)

    2011-02-23

    The increasing use of wind power as a source of electricity poses new challenges with regard to both power production and load balance in the electricity grid. This new source of energy is volatile and highly variable. The only way to integrate such power into the grid is to develop reliable and accurate wind power forecasting systems. Electricity generated from wind power can be highly variable at several different timescales: sub-hourly, hourly, daily, and seasonally. Wind energy, like other electricity sources, must be scheduled. Although wind power forecasting methods are used, the ability to predict wind plant output remains relatively low for short-term operation. Because instantaneous electrical generation and consumption must remain in balance to maintain grid stability, wind power's variability can present substantial challenges when large amounts of wind power are incorporated into a grid system. A critical issue is ramp events, which are sudden and large changes (increases or decreases) in wind power. This report presents an overview of current ramp definitions and state-of-the-art approaches in ramp event forecasting.

  17. Wide-temperature integrated operational amplifier

    Science.gov (United States)

    Mojarradi, Mohammad (Inventor); Levanas, Greg (Inventor); Chen, Yuan (Inventor); Cozy, Raymond S. (Inventor); Greenwell, Robert (Inventor); Terry, Stephen (Inventor); Blalock, Benjamin J. (Inventor)

    2009-01-01

    The present invention relates to a reference current circuit. The reference circuit comprises a low-level current bias circuit, a voltage proportional-to-absolute temperature generator for creating a proportional-to-absolute temperature voltage (VPTAT), and a MOSFET-based constant-IC regulator circuit. The MOSFET-based constant-IC regulator circuit includes a constant-IC input and constant-IC output. The constant-IC input is electrically connected with the VPTAT generator such that the voltage proportional-to-absolute temperature is the input into the constant-IC regulator circuit. Thus the constant-IC output maintains the constant-IC ratio across any temperature range.

  18. Influence of hydrogen temperature on the stability of a rocket engine combustor operated with hydrogen and oxygen

    Science.gov (United States)

    Gröning, Stefan; Hardi, Justin; Suslov, Dmitry; Oschwald, Michael

    2017-03-01

    Since the late 1960s, low hydrogen injection temperature is known to have a destabilising effect on rocket engines with the propellant combination hydrogen/oxygen. Self-excited combustion instabilities of the first tangential mode have been found recently in a research rocket combustor operated with the propellant combination hydrogen/oxygen with a hydrogen temperature of 95 K. A hydrogen temperature ramping experiment has been performed with this research combustor to analyse the impact of hydrogen temperature on the self-excited combustion instabilities. The temperature was varied between 40 and 135 K. Contrary to past results found in literature, the combustor was found to be stable at low hydrogen temperatures while increased oscillation amplitudes of the first tangential mode were found at higher temperatures of around 100 K and above, which is consistent with previous observations of instabilities in this combustor. Further analysis shows that hydrogen temperature has a strong impact on the combustion chamber resonance frequencies. By varying the hydrogen injection temperature, the frequency of the first tangential mode is shifted to coincide with the second longitudinal resonance frequency of the liquid oxygen injector. Excitation of combustion chamber pressure oscillations was observed during such events.

  19. Test plans of the high temperature test operation at HTTR

    Energy Technology Data Exchange (ETDEWEB)

    Sakaba, Nariaki; Nakagawa, Shigeaki; Takada, Eiji [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment] [and others

    2003-03-01

    HTTR plans a high temperature test operation as the fifth step of the rise-to-power tests to achieve a reactor outlet coolant temperature of 950 degrees centigrade in the 2003 fiscal year. Since HTTR is the first HTGR in Japan which uses coated particle fuel as its fuel and helium gas as its coolant, it is necessary that the plan of the high temperature test operation is based on the previous rise-to-power tests with a thermal power of 30 MW and a reactor outlet coolant temperature at 850 degrees centigrade. During the high temperature test operation, reactor characteristics, reactor performances and reactor operations are confirmed for the safety and stability of operations. This report describes the evaluation result of the safety confirmations of the fuel, the control rods and the intermediate heat exchanger for the high temperature test operation. Also, problems which were identified during the previous operations are shown with their solution methods. Additionally, there is a discussion on the contents of the high temperature test operation. As a result of this study, it is shown that the HTTR can safely achieve a thermal power of 30 MW with the reactor outlet coolant temperature at 950 degrees centigrade. (author)

  20. Operation of an opamp at liquid helium temperature.

    Science.gov (United States)

    Ng, K.-W.

    1994-02-01

    The stray capacitance between long wires in a cryogenics systems will slow down measurement rate, and also introduce unnecessary noise pick up. It is necessary to install the preamplifier as close to the signal source as possible to diminish the capacitive coupling effects. The most commonly used semiconducting device for this purpose is the MOSFET, which can function at liquid helium temperatures. Under special operation procedures, an all MOSFET operational amplifier can also be operated at liquid helium temperature. The use of opamp will simplify the construction of more complicated circuitry for low temperature applications.

  1. High Operating Temperature, Radiation-Hard MIM Thermophotovoltaic Converters Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Spire Corporation proposes to investigate InGaAs thermophotovoltaic (TPV) cells optimized for high temperature operation (~150C) and radiation hardness against the...

  2. Coupling Measurements and Corrections for the Combined Ramp and Squeeze

    CERN Document Server

    Persson, Tobias Hakan Bjorn; Langner, Andy Sven; Malina, Lukas; Maclean, Ewen Hamish; Coello De Portugal - Martinez Vazquez, Jaime Maria; Redaelli, Stefano; Salvachua Ferrando, Belen Maria; Schaumann, Michaela; Solfaroli Camillocci, Matteo; Skowronski, Piotr Krzysztof; Tomas Garcia, Rogelio; Garcia-Tabares Valdivieso, Ana; Wenninger, Jorg; CERN. Geneva. ATS Department

    2016-01-01

    In operation of the LHC the ramp and the squeeze process have been independent beam processes up to now. Making them into a combined process would save time to reach the point where the beams are brought to collision. This would increase the integrated luminosity provided by the LHC. One possible source of problems could be deviation from the ideal optics and in particular the control of the transverse coupling. In this report we focus on the coupling measurements that were taken during the Combined Ramp and Squeeze (CRS) MD.

  3. Ramping up PCI production

    Energy Technology Data Exchange (ETDEWEB)

    Bergsma, D.; Kieftenbeld, B.; Bol, L. [Corus Strip Products IJmuiden (Netherlands). Blast Furnace Dept.

    2008-07-01

    This paper described the improvements at the Corus Strip Products IJmuiden coal preparation plant and injection facilities that have resulted in ultra high productivities and very low coke rates of the blast furnaces. Pulverized coal injection (PCI) began at the steelmaking plant 25 years ago. Since then, an increased coal preparation output has been realized each year. The capacity of the mills and the injection systems were increased from about 70 tons/h to over 200 tons/h, thereby allowing a steady decrease in coke rate per ton of hot metal with a considerable increase in hot metal production from the blast furnaces. Many modifications were in hardware, but much of the increase in productivity was due to increasing the aimed pulverized coal (PC) particle size, selecting different coals and improving process control in both milling and injection facilities. Depending on the coal variety, the specific PCI-rates could reach over 250 kg/thm. The excellent performance was made possible by improving key factors such as burden quality, burdening, cast house performance and installation reliability. The modifications also solved constraints in working pressure; uptake pulverized coal moisture content; inlet and outlet air temperature; and injection rate stability. Coal selection was based on handlability, chemical composition and economics. 1 tab., 9 figs.

  4. New energy ramping control system in the Pohang Light Source Storage Ring

    CERN Document Server

    Kim, E S; Seo, J H; Nam, S H

    2003-01-01

    A new energy ramping control system is developed to increase electron beam energy from 2.0 GeV to 2.5 GeV in the Pohang Light Source storage ring. The control system shows faster energy ramping and more stable beam characteristics than the previous energy ramping control system that consists of an operator interface workstation, subsystem control computer and machine interface units. The previous system controls current settings of the magnet power supplies in multiple steps with different energy increment rate during the energy ramping. In order to improve synchronization of the magnet power supply systems and beam stabilities during the energy ramping, we developed the energy ramping controller hardware that is controlled using a network of optical fibers. Thus, the new ramping system is able to control more synchronously the magnet power supplies with a constant energy increment rate during the energy ramping. With this reliable synchronization, it is also possible to perform the energy de-ramping step fro...

  5. Nonlinear Predictive Control for PEMFC Stack Operation Temperature

    Institute of Scientific and Technical Information of China (English)

    LI Xi; CAO Guang-yi; ZHU Xin-jian

    2005-01-01

    Operating temperature of proton exchange membrane fuel cell stack should be controlled within a special range. The input-output data and operating experiences were used to establish a PEMFC stack model and operating temperature control system. A nonlinear predictive control algorithm based on fuzzy model was presented for a family of complex system with severe nonlinearity such as PEMFC. Based on the obtained fuzzy model, a discrete optimization of the control action was carried out according to the principle of Branch and Bound method. The test results demonstrate the effectiveness and advantage of this approach.

  6. Traffic Congestion Mechanism in Two Ramp Systems

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xiao-Mei; SONG Gui-Cui; SONG Yu-Kun

    2011-01-01

    The aim of this paper is to study traffic properties in an on/off-ramp system with a bus stop close to the on/off ramp.The location of the bus stop in the on/off-ramp (thereafter downstream or upstream case) is discussed.The simulation results show that in the two ramp systems, the reasons for traffic congestions are different.In the on-ramp system, buses and cars coming from on-ramp interweave each other, while in the off-ramp system, buses interweave with cars exiting to off-ramp.Thus, in the on-ramp (off-ramp) system, the upstream (downstream) bus stop is helpful to reduce the interweaving situation.Moreover, the negative effect will disappear when the distance between the bus stop and the on/off-ramp is more than 20 cells (i.e.150 m).These qualitative findings may provide some suggestions on traffic management and optimization.

  7. Operating temperatures for a convectively cooled recessed incandescent light fixture

    Energy Technology Data Exchange (ETDEWEB)

    Yarbrough, D.W.; Toor, I.

    1980-12-01

    Test results are given for the operation of a recessed incandescent light fixture intended for residential use. The fixture is labeled for use in direct contact with attic thermal insulation. Temperature control of the powered fixture is provided by convective heat transfer from the ceiling side of the fixture. The fixture was operated at power levels up to two times the rated power of 75 watts and under thermal insulations up to R-40. In all operating configurations tested the fixture surface in contact with attic insulation was found to be less than 175/sup 0/C. The observed surface temperatures are judged to be safe for operation in contact with loose-fill or batt-type insulations. It was observed that the power leads inside one fixture configuration are exposed to temperatures as high as 168/sup 0/C. The electrical insulation could, therefore, have a limited life. The properties of the internal fixture wiring were not, however, studied in detail.

  8. LHC Report: Intensity ramp-up

    CERN Multimedia

    Mike Lamont for the LHC Team

    2012-01-01

    The first stable beams at 4 TeV were declared on Thursday, 5 April with 3 bunches per beam. This marked the start of the intensity ramp-up, which aims to get back up to 1380 bunches per beam as quickly as is safely possible.   The next couple of days saw fills with 47, 84 and 264 bunches per beam and on Sunday, 8 April the move was made to 624 bunches. With the squeeze to 60 cm in place, 624 bunches with reasonably high bunch intensities of around 1.3 to 1.4 x1011 protons per bunch have already yielded respectable peak luminosities of up to 2.5 x1033 cm-2s-1. Following a lot of hard work during the Christmas technical stop, machine availability is very good at the moment. The ramp-up in the number of bunches is accompanied by a series of checks aimed to make sure the machine protection systems and operational procedures are in a good enough shape to safely deal with the beam intensity. 624 bunches at 4 TeV already represents an energy over 50 MJ and serious damage potential. The next few days sh...

  9. Current ramp-up with lower hybrid current drive in EAST

    Science.gov (United States)

    Ding, B. J.; Li, M. H.; Fisch, N. J.; Qin, H.; Li, J. G.; Wilson, J. R.; Kong, E. H.; Zhang, L.; Wei, W.; Li, Y. C.; Wang, M.; Xu, H. D.; Gong, X. Z.; Shen, B.; Liu, F. K.; Shan, J. F.

    2012-12-01

    More economical fusion reactors might be enabled through the cyclic operation of lower hybrid current drive. The first stage of cyclic operation would be to ramp up the plasma current with lower hybrid waves alone in low-density plasma. Such a current ramp-up was carried out successfully on the EAST tokamak. The plasma current was ramped up with a time-averaged rate of 18 kA/s with lower hybrid (LH) power. The average conversion efficiency Pel/PLH was about 3%. Over a transient phase, faster ramp-up was obtained. These experiments feature a separate measurement of the L/R time at the time of current ramp up.

  10. Improved Wide Operating Temperature Range of Li-Ion Cells

    Science.gov (United States)

    Smart, Marshall C.; Bugga, Ratnakumar V.

    2013-01-01

    Future NASA missions aimed at exploring the Moon, Mars, and the outer planets require rechargeable batteries that can operate over a wide temperature range (-60 to +60 C) to satisfy the requirements of various applications including landers, rovers, penetrators, CEV, CLV, etc. This work addresses the need for robust rechargeable batteries that can operate well over a wide temperature range. The Department of Energy (DoE) has identified a number of technical barriers associated with the development of Liion rechargeable batteries for PHEVs. For this reason, DoE has interest in the development of advanced electrolytes that will improve performance over a wide range of temperatures, and lead to long life characteristics (5,000 cycles over a 10-year life span). There is also interest in improving the high-voltage stability of these candidate electrolyte systems to enable the operation of up to 5 V with high specific energy cathode materials. Currently, the state-of-the-art lithium-ion system has been demonstrated to operate over a wide range of temperatures (-40 to +40 C); however, the rate capability at the lower temperatures is very poor. In addition, the low-temperature performance typically deteriorates rapidly upon being exposed to high temperatures. A number of electrolyte formulations were developed that incorporate the use of electrolyte additives to improve the high-temperature resilience, low-temperature power capability, and life characteristics of methyl propionate (MP)-based electrolyte solutions. These electrolyte additives include mono-fluoroethylene carbonate (FEC), lithium oxalate, vinylene carbonate (VC), and lithium bis(oxalate borate) (LiBOB), which have previously been shown to result in improved high-temperature resilience of all carbonate-based electrolytes. These MP-based electrolytes with additives have been shown to have improved performance in experiments with MCMB-LiNiCoAlO2 cells.

  11. Extreme operative temperatures are better descriptors of the thermal environment than mean temperatures.

    Science.gov (United States)

    Camacho, Agustín; Trefaut Rodrigues, Miguel; Navas, Carlos

    2015-01-01

    In ecological studies of thermal biology the thermal environment is most frequently described using the mean or other measures of central tendency in environmental temperatures. However, this procedure may hide biologically relevant thermal variation for ectotherms, potentially misleading interpretations. Extremes of operative temperatures (EOT) can help with this problem by bracketing the thermal environment of focal animals. Within this paper, we quantify how mean operative temperatures relate to the range of simultaneously available operative temperatures (a measure of error). We also show how EOT: 1) detect more thermal differences among microsites than measures of central tendency, like the mean OT, 2) allow inferring on microsite use by ectothermic animals, and 3) clarify the relationships between field operative temperatures and temperatures measured at weather stations (WS). To do that, we explored operative temperatures measured at four sites of the Brazilian Caatingas and their correspondent nearest weather stations. We found that the daily mean OT can hide temperature ranges of 41 °C simultaneously available at our study sites. In addition, EOT detected more thermal differences among microsites than central quantiles. We also show how EOT allow inferring about microsite use of ectothermic animals in a given site. Finally, the daily maximum temperature and the daily temperature range measured at WSs predicted well the minimum available field OT at localities many kilometers away. Based on our results, we recommend the use of EOT, instead of mean OT, in thermal ecology studies.

  12. Strategies for Lowering Solid Oxide Fuel Cells Operating Temperature

    Directory of Open Access Journals (Sweden)

    Albert Tarancón

    2009-11-01

    Full Text Available Lowering the operating temperature of solid oxide fuel cells (SOFCs to the intermediate range (500–700 ºC has become one of the main SOFC research goals. High operating temperatures put numerous requirements on materials selection and on secondary units, limiting the commercial development of SOFCs. The present review first focuses on the main effects of reducing the operating temperature in terms of materials stability, thermo-mechanical mismatch, thermal management and efficiency. After a brief survey of the state-of-the-art materials for SOFCs, attention is focused on emerging oxide-ionic conductors with high conductivity in the intermediate range of temperatures with an introductory section on materials technology for reducing the electrolyte thickness. Finally, recent advances in cathode materials based on layered mixed ionic-electronic conductors are highlighted because the decreasing temperature converts the cathode into the major source of electrical losses for the whole SOFC system. It is concluded that the introduction of alternative materials that would enable solid oxide fuel cells to operate in the intermediate range of temperatures would have a major impact on the commercialization of fuel cell technology.

  13. Anodes for Solid Oxide Fuel Cells Operating at Low Temperatures

    DEFF Research Database (Denmark)

    Abdul Jabbar, Mohammed Hussain

    An important issue that has limited the potential of Solid Oxide Fuel Cells (SOFCs) for portable applications is its high operating temperatures (800-1000 ºC). Lowering the operating temperature of SOFCs to 400-600 ºC enable a wider material selection, reduced degradation and increased lifetime....... On the other hand, low-temperature operation poses serious challenges to the electrode performance. Effective catalysts, redox stable electrodes with improved microstructures are the prime requisite for the development of efficient SOFC anodes. The performance of Nb-doped SrT iO3 (STN) ceramic anodes...... at 400ºC. The potential of using WO3 ceramic as an alternative anode materials has been explored. The relatively high electrode polarization resistance obtained, 11 Ohm cm2 at 600 ºC, proved the inadequate catalytic activity of this system for hydrogen oxidation. At the end of this thesis...

  14. Nylon coil actuator operating temperature range and stiffness

    Science.gov (United States)

    Kianzad, Soheil; Pandit, Milind; Bahi, Addie; Rafie Ravandi, Ali; Ko, Frank; Spinks, Geoffrey M.; Madden, John D. W.

    2015-04-01

    Components in automotive and aerospace applications require a wide temperature range of operation. Newly discovered thermally active Baughman muscle potentially provides affordable and viable solutions for driving mechanical devices by heating them from room temperature, but little is known about their operation below room temperature. We study the mechanical behavior of nylon coil actuators by testing elastic modulus and by investigating tensile stroke as a function of temperature. Loads that range from 35 MPa to 155 MPa were applied. For the nylon used and the coiling conditions, active thermal contraction totals 19.5 % when the temperature is raised from -40 °C to 160 °C. The thermal contraction observed from -40 °C to 20°C is only ~2 %, whereas between 100 and 160 °C the contraction is 10 %. A marked increase in thermal contraction is occurs in the vicinity of the glass transition temperature (~ 45°C). The elastic modulus drops as temperature increases, from ~155 MPa at - 40 °C to 35 MPa at 200 °C. Interestingly the drop in active contraction with increasing load is small and much less than might be expected given the temperature dependence of modulus.

  15. A high voltage programmable ramp generator

    Science.gov (United States)

    Upadhyay, J.; Joshi, M. J.; Deshpande, P. P.; Sharma, M. L.; Navathe, C. P.

    2008-05-01

    In this paper, a ramp generator with programmable slope is presented. It consists of a high voltage step generator, followed by integrator. The capacitor and inductor in the integrator are designed such that they can be varied by a microcontroller. This circuit generates two bipolar ramps with fastest speed <1ns and provides continuous speed variation from 6to30ns for a ramp of 500V. This is being developed as a part of automated streak camera for deflection of electron beam.

  16. Heating a chemical current source which operates at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Mitsumata, T.; Khosikhara, N.

    1983-02-14

    A chamber for catalytic ignition of hydrogen or gasoline is installed in a chemical current source. The isolated heat heats the chemical current source with a low temperature of the environment providing its optimal operational conditions. The fuel is fed into the chamber from a tank or chamber located in the body of the chemical current source.

  17. 980nm diode laser pump modules operating at high temperature

    Science.gov (United States)

    Campbell, Jenna; Semenic, Tadej; Leisher, Paul; Bhunia, Avijit; Mashanovitch, Milan; Renner, Daniel

    2016-03-01

    Existing thermal management technologies for diode laser pumps place a significant load on the size, weight and power consumption of High Power Solid State and Fiber Laser systems, thus making current laser systems very large, heavy, and inefficient in many important practical applications. This problem is being addressed by the team formed by Freedom Photonics and Teledyne Scientific through the development of novel high power laser chip array architectures that can operate with high efficiency when cooled with coolants at temperatures higher than 50 degrees Celsius and also the development of an advanced thermal management system for efficient heat extraction from the laser chip array. This paper will present experimental results for the optical, electrical and thermal characteristics of 980 nm diode laser pump modules operating effectively with liquid coolant at temperatures above 50 degrees Celsius, showing a very small change in performance as the operating temperature increases from 20 to 50 degrees Celsius. These pump modules can achieve output power of many Watts per array lasing element with an operating Wall-Plug-Efficiency (WPE) of >55% at elevated coolant temperatures. The paper will also discuss the technical approach that has enabled this high level of pump module performance and opportunities for further improvement.

  18. Estimation of operative temperature in buildings using artificial neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Soleimani-Mohseni, M.; Fahlen, P. [Department of Building Services Engineering, Chalmers University of Technology, Goeteborg (Sweden); Thomas, B. [Department of Signals and Systems, Chalmers University of Technology, Campus Lindholmen, Goeteborg (Sweden)

    2006-07-01

    In this article, the problem how to obtain models for estimation of the operative temperature in rooms and buildings is discussed. Identification experiments have been carried out in two different buildings and different linear and non-linear estimation models have been identified based on these experiments. For the buildings studied, it is shown that the operative temperature can be estimated fairly well by using variables, which are more easily measured, such as the indoor and outdoor temperatures, the electrical power use in the room, the wall temperatures, the ventilation flow rates and the time of day. It is also shown that non-linear artificial neural network models (ANN-models), in general, give better estimations than linear ARX-models. The most accurate estimation models were obtained using feed-forward ANN-models with one hidden layer of neurons and using Levenberg-Marquardt's training algorithms. In one of the buildings, it is shown that for non-linear models but not for linear, the estimations are improved much when using the time of day as an input signal. This shows that the time of day affects the operative temperature in a non-linear manner. (author)

  19. Computer programs for pressurization (RAMP) and pressurized expulsion from a cryogenic liquid propellant tank

    Science.gov (United States)

    Masters, P. A.

    1974-01-01

    An analysis to predict the pressurant gas requirements for the discharge of cryogenic liquid propellants from storage tanks is presented, along with an algorithm and two computer programs. One program deals with the pressurization (ramp) phase of bringing the propellant tank up to its operating pressure. The method of analysis involves a numerical solution of the temperature and velocity functions for the tank ullage at a discrete set of points in time and space. The input requirements of the program are the initial ullage conditions, the initial temperature and pressure of the pressurant gas, and the time for the expulsion or the ramp. Computations are performed which determine the heat transfer between the ullage gas and the tank wall. Heat transfer to the liquid interface and to the hardware components may be included in the analysis. The program output includes predictions of mass of pressurant required, total energy transfer, and wall and ullage temperatures. The analysis, the algorithm, a complete description of input and output, and the FORTRAN 4 program listings are presented. Sample cases are included to illustrate use of the programs.

  20. Numerical investigation on jet interaction with a compression ramp

    Institute of Scientific and Technical Information of China (English)

    Zhen Huaping; Gao Zhenxun; Lee Chunhian

    2013-01-01

    A numerical investigation on jet interaction in supersonic laminar flow with a compression ramp is performed utilizing the AUSMDV scheme and a parallel solver.Several parameters dominating the interference flowfield are studied after defining the relative increment of normal force and the jet amplification factor as the evaluation criterion of jet control performance.The computational results show that most features of the interaction flowfield between the transverse jet and the ramp are similar to those between a jet and a flat plate,except that the flow structures are more complicated and the low-pressure region behind the jet is less extensive.The relative force increment and the jet amplification factor both increase with the distance between the jet and the ramp shortening till quintuple jet diameters.Inconspicuous difference is observed between the jet-before-ramp and jet-on-ramp cases.The variation of the injection angle changes the extent of the separation region,the plateau pressure,and the peak pressure near the jet.In the present computational conditions,120° is indicated relatively optimal among all the injection angles studied.For cold gas simulations,although little influence of the jet temperature on the pressure distribution near the jet is observed under the computation model and the flow parameters studied,reducing jet temperature somehow benefits the improvement of the normal force and the jet efficiency.When the pressure ratio of jet to freestream is fixed,the relative force increment varies little when increasing the freestream Mach number,while the jet amplification factor increases.

  1. Evaluation of Silicon-on-Insulator HTOP-01 Operational Amplifier for Wide Temperature Operation

    Science.gov (United States)

    Patterson, Richard; Hammoud, Ahmad; Elbuluk, Malik

    2008-01-01

    Electronics capable of operation under extreme temperatures are required in many of NASA space exploration missions. Aerospace and military applications, as well as some terrestrial industries constitute environments where electronic systems are anticipated to be exposed to extreme temperatures and wide-range thermal swings. Electronics that are able to withstand and operate efficiently in such harsh environments would simplify, if not eliminate, traditional thermal control elements and their associated structures for proper ambient operation. As a result, overall system mass would be reduced, design would be simplified, and reliability would be improved. Electronic parts that are built utilizing silicon-on-insulator (SOI) technology are known to offer better radiation-tolerance compared to their conventional silicon counterparts, provide faster switching, and consume less power. They also exhibit reduced leakage current and, thus, they are often tailored for high temperature operation. These attributes make SOI-based devices suitable for use in harsh environments where extreme temperatures and wide thermal swings are anticipated. A new operational amplifier, based on silicon-on-insulator technology and geared for high temperature well-logging applications, was recently introduced by Honeywell Corporation. This HTOP-01 dual precision operational amplifier is a low power device, operates on a single supply, and has an internal oscillator and an external clocking option [1]. It is rated for operation from -55 C to +225 C with a maximum output current capability of 50 mA. The amplifier chip is designed as a 14-pin, hermetically-sealed device in a ceramic package. Table I shows some of the device manufacturer s specifications.

  2. Analysis of power ramp rate and minimum power controllability of the MMS model for a plant dynamics analysis of a Prototype SFR

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eui Kwang; Kim, Dehee; Joo, Hyungkook; Lee, Taeho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    A full plant dynamic model was developed for a prototype SFR using the Modular Modeling System (MMS). It includes the modeling of various subsystems such as the neutronics, primary and intermediate sodium systems of the NSSS, steam and water systems of the BOP, BOP controls, and the supervisory plant controls. The NSSS model is subdivided into component models, such as a Core, IHXs, Pumps, SGs, and the rest of the NSSS loop model. The BOP model is subdivided into a steam subsystem, feedwater subsystem, and preheater subsystem. Plant transient tests were performed to study the operational considerations. It includes varying the power ramp rate and studying the controllability at minimum power. Plant transient tests were performed to study operational considerations by using the MMS model for a prototype SFR. It includes varying the power ramp rate, studying the controllability at the minimum power set point. At a power ramp rate of higher than 2%, the steam temperature has a large deviation from the target. As the power set point decreases, the PHTS hot leg temperature and steam temperature tend to have higher deviations. After further refinement of the MMS model, it can be useful for developing the plant operation logics of the prototype SFR.

  3. Amplifier circuit operable over a wide temperature range

    Science.gov (United States)

    Kelly, Ronald D.; Cannon, William L.

    1979-01-01

    An amplifier circuit having stable performance characteristics over a wide temperature range from approximately 0.degree. C up to as high as approximately 500.degree. C, such as might be encountered in a geothermal borehole. The amplifier utilizes ceramic vacuum tubes connected in directly coupled differential amplifier pairs having a common power supply and a cathode follower output stage. In an alternate embodiment, for operation up to 500.degree. C, positive and negative power supplies are utilized to provide improved gain characteristics, and all electrical connections are made by welding. Resistor elements in this version of the invention are specially heat treated to improve their stability with temperature.

  4. Cathodes for Solid Oxide Fuel Cells Operating at Low Temperatures

    DEFF Research Database (Denmark)

    Samson, Alfred Junio

    This dissertation focuses on the development of nanostructured cathodes for solid oxide fuel cells (SOFCs) and their performance at low operating temperatures. Cathodes were mainly fabricated by the infiltration method, whereby electrocatalysts are introduced onto porous, ionic conducting backbones......degreeC. The most promising cathode was integrated onto an anode supported cell and it was found that the cell exhibits electrochemical stability with no measureable degradation during 1500 h operation at 700degreeC. LaCoO3 and Co3O4 infiltrated - CGO cathodes were also investigated and revealed...

  5. A nonintrusive method for measuring the operating temperature of a solenoid-operated valve

    Science.gov (United States)

    Kryter, Robert C.

    Experimental data are presented to show that the in-service operating temperature of a solenoid operated valve (SOV) can be inferred simply and nondisruptively by using the copper winding of the solenoid coil as a self-indicating, permanently available resistance thermometer. The principal merits of this approach include: (1) there is no need for an add-on temperature sensor, (2) the true temperature of a critical and likely the hottest, part of the SOV (namely, the electrical coil) is measured directly, (3) temperature readout can be provided at any location at which the SOV electrical lead wires are accessible (even though remote from the valve), (4) the SOV need not be disturbed (whether normally energized or deenergized) to measure its temperature in situ, and (5) the method is applicable to all types of SOVs, large and small, ac- and dc-powered. Laboratory tests comparing temperatures measured both by coil resistance and by a conventional thermometer placed in contact with the external surface of the potted solenoid coil indicate that temperature within the coil may be on the order of 40 C higher than that measured externally, a fact that is important to life-expectancy calculations made on the basis of Arrhenius theory. Field practicality is illustrated with temperature measurements made using this method on a SOV controlling the flow of refrigerant in a large chilled-water air-conditioning system.

  6. Effect of operating microscope light on brain temperature during craniotomy.

    Science.gov (United States)

    Gayatri, Parthasarathi; Menon, Girish G; Suneel, Puthuvassery R

    2013-07-01

    Operating microscopes used during neurosurgery are fitted with xenon light. Burn injuries have been reported because of xenon microscope lighting as the intensity of xenon light is 300 W. We designed this study to find out if the light of operating microscope causes an increase in temperature of the brain tissue, which is exposed underneath. Twenty-one adult patients scheduled for elective craniotomies were enrolled. Distal esophageal temperature (T Eso), brain temperature under the microscope light (T Brain), and brain temperature under dura mater (T Dura) were measured continuously at 15-minute intervals during microscope use. The irrigation fluid temperature, room temperature, intensity of the microscope light, and the distance of the microscope from the brain surface were kept constant. The average age of the patients was 44±15 years (18 males and 3 females). The mean duration of microscope use was 140±39 minutes. There were no significant changes in T Brain and T Dura and T Eso over time. T Dura was significantly lower than T Brain both at time 0 and 60 minutes but not at 90 minutes. T Brain was significantly lower than T Eso both at time 0 and 60 minutes but not at 90 minutes. The T Dura remained significantly lower than T Eso at 0, 60, and 90 minutes. Our study shows that there is no significant rise in brain temperature under xenon microscope light up to 120 minutes duration, at intensity of 60% to 70%, from a distance of 20 to 25 cm from the brain surface.

  7. Performance of High Temperature Operational Amplifier, Type LM2904WH, under Extreme Temperatures

    Science.gov (United States)

    Patterson, Richard; Hammoud, Ahmad; Elbuluk, Malik

    2008-01-01

    Operation of electronic parts and circuits under extreme temperatures is anticipated in NASA space exploration missions as well as terrestrial applications. Exposure of electronics to extreme temperatures and wide-range thermal swings greatly affects their performance via induced changes in the semiconductor material properties, packaging and interconnects, or due to incompatibility issues between interfaces that result from thermal expansion/contraction mismatch. Electronics that are designed to withstand operation and perform efficiently in extreme temperatures would mitigate risks for failure due to thermal stresses and, therefore, improve system reliability. In addition, they contribute to reducing system size and weight, simplifying its design, and reducing development cost through the elimination of otherwise required thermal control elements for proper ambient operation. A large DC voltage gain (100 dB) operational amplifier with a maximum junction temperature of 150 C was recently introduced by STMicroelectronics [1]. This LM2904WH chip comes in a plastic package and is designed specifically for automotive and industrial control systems. It operates from a single power supply over a wide range of voltages, and it consists of two independent, high gain, internally frequency compensated operational amplifiers. Table I shows some of the device manufacturer s specifications.

  8. NGNP/HTE full-power operation at reduced high-temperature heat exchanger temperatures.

    Energy Technology Data Exchange (ETDEWEB)

    VIlim, R.; Nuclear Engineering Division

    2009-03-12

    Operation of the Next Generation Nuclear Plant (NGNP) with reduced reactor outlet temperature at full power was investigated for the High Temperature Electrolysis (HTE) hydrogen-production application. The foremost challenge for operation at design temperature is achieving an acceptably long service life for heat exchangers. In both the Intermediate Heat Exchanger (IHX) and the Process Heat Exchanger (PHX) (referred to collectively as high temperature heat exchangers) a pressure differential of several MPa exists with temperatures at or above 850 C. Thermal creep of the heat exchanger channel wall may severely limit heat exchanger life depending on the alloy selected. This report investigates plant performance with IHX temperatures reduced by lowering reactor outlet temperature. The objective is to lower the temperature in heat transfer channels to the point where existing materials can meet the 40 year lifetime needed for this component. A conservative estimate for this temperature is believed to be about 700 C. The reactor outlet temperature was reduced from 850 C to 700 C while maintaining reactor power at 600 MWt and high pressure compressor outlet at 7 MPa. We included a previously reported design option for reducing temperature at the PHX. Heat exchanger lengths were adjusted to reflect the change in performance resulting from coolant property changes and from resizing related to operating-point change. Turbomachine parameters were also optimized for the new operating condition. An integrated optimization of the complete system including heat transfer equipment was not performed. It is estimated, however, that by performing a pinch analysis the combined plant efficiency can be increased from 35.5 percent obtained in this report to a value between 38.5 and 40.1 percent. Then after normalizing for a more than three percent decrease in commodities inventory compared to the reference plant, the commodities-normalized efficiency lies between 40.0 and 41.3. This

  9. Online Analysis of Wind and Solar Part I: Ramping Tool

    Energy Technology Data Exchange (ETDEWEB)

    Etingov, Pavel V.; Ma, Jian; Makarov, Yuri V.; Subbarao, Krishnappa

    2012-01-31

    To facilitate wider penetration of renewable resources without compromising system reliability concerns arising from the lack of predictability of intermittent renewable resources, a tool for use by California Independent System Operator (CAISO) power grid operators was developed by Pacific Northwest National Laboratory (PNNL) in conjunction with CAISO with funding from California Energy Commission. This tool predicts and displays additional capacity and ramping requirements caused by uncertainties in forecasts of loads and renewable generation. The tool is currently operational in the CAISO operations center. This is one of two final reports on the project.

  10. The Joint Control of Variable Speed and On-Ramp Metering for Urban Expressway

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The traffic performance of urban expressway is subject to non-recurring and recurring events, which may cause heavy congestion and vehicles long queuing on ramps. The low performance may bring more traffic delay to the whole network of urban road. This paper presents a new method, the joint control of variable speed control and on-ramp metering, which attempts to improve the level of traffic operations on urban expressway. By analyzing traffic flow on urban expressway, an optimum control strategy of variable speed and on-ramp metering is established in the paper.``

  11. Temperature mapping of operating nanoscale devices by scanning probe thermometry

    Science.gov (United States)

    Menges, Fabian; Mensch, Philipp; Schmid, Heinz; Riel, Heike; Stemmer, Andreas; Gotsmann, Bernd

    2016-03-01

    Imaging temperature fields at the nanoscale is a central challenge in various areas of science and technology. Nanoscopic hotspots, such as those observed in integrated circuits or plasmonic nanostructures, can be used to modify the local properties of matter, govern physical processes, activate chemical reactions and trigger biological mechanisms in living organisms. The development of high-resolution thermometry techniques is essential for understanding local thermal non-equilibrium processes during the operation of numerous nanoscale devices. Here we present a technique to map temperature fields using a scanning thermal microscope. Our method permits the elimination of tip-sample contact-related artefacts, a major hurdle that so far has limited the use of scanning probe microscopy for nanoscale thermometry. We map local Peltier effects at the metal-semiconductor contacts to an indium arsenide nanowire and self-heating of a metal interconnect with 7 mK and sub-10 nm spatial temperature resolution.

  12. First beam test of a combined ramp and squeeze at LHC

    CERN Document Server

    Wenninger, Jorg; Coello De Portugal - Martinez Vazquez, Jaime Maria; Gorzawski, Arkadiusz; Redaelli, Stefano; Schaumann, Michaela; Solfaroli Camillocci, Matteo; CERN. Geneva. ATS Department

    2015-01-01

    With increasing maturity of LHC operation it is possible to envisage more complex beam manipulations. At the same time operational efficiency receives increasing attention. So far ramping the beams to their target energy and squeezing the beams to smaller or higher beta are decoupled at the LHC. (De-)squeezing is always performed at the target energy, currently 6.5 TeV. Studies to combine the ramp and squeeze processes have been made for the LHC since 2011, but so far no experimental test with beam had ever performed. This note describes the first machine experiment with beam aiming at validating the combination of ramp and squeeze, the so-called combined ramp and squeeze (CRS).

  13. 14 CFR 25.1527 - Ambient air temperature and operating altitude.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Ambient air temperature and operating... Information Operating Limitations § 25.1527 Ambient air temperature and operating altitude. The extremes of the ambient air temperature and operating altitude for which operation is allowed, as limited...

  14. Li/CFx Cells Optimized for Low-Temperature Operation

    Science.gov (United States)

    Smart, Marshall C.; Whitacre, Jay F.; Bugga, Ratnakumar V.; Prakash, G. K. Surya; Bhalla, Pooja; Smith, Kiah

    2009-01-01

    Some developments reported in prior NASA Tech Briefs articles on primary electrochemical power cells containing lithium anodes and fluorinated carbonaceous (CFx) cathodes have been combined to yield a product line of cells optimized for relatively-high-current operation at low temperatures at which commercial lithium-based cells become useless. These developments have involved modifications of the chemistry of commercial Li/CFx cells and batteries, which are not suitable for high-current and low-temperature applications because they are current-limited and their maximum discharge rates decrease with decreasing temperature. One of two developments that constitute the present combination is, itself, a combination of developments: (1) the use of sub-fluorinated carbonaceous (CFx wherein xLiBF4 dissolved at a concentration of 0.5 M in a mixture of four volume parts of 1,2 dimethoxyethane with one volume part of propylene carbonate. The proportion, x, of fluorine in the cathode in such a cell lies between 0.5 and 0.9. The best of such cells fabricated to date have exhibited discharge capacities as large as 0.6 A h per gram at a temperature of 50 C when discharged at a rate of C/5 (where C is the magnitude of the current, integrated for one hour, that would amount to the nominal charge capacity of a cell).

  15. Ramp Forecasting Performance from Improved Short-Term Wind Power Forecasting: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J.; Florita, A.; Hodge, B. M.; Freedman, J.

    2014-05-01

    The variable and uncertain nature of wind generation presents a new concern to power system operators. One of the biggest concerns associated with integrating a large amount of wind power into the grid is the ability to handle large ramps in wind power output. Large ramps can significantly influence system economics and reliability, on which power system operators place primary emphasis. The Wind Forecasting Improvement Project (WFIP) was performed to improve wind power forecasts and determine the value of these improvements to grid operators. This paper evaluates the performance of improved short-term wind power ramp forecasting. The study is performed for the Electric Reliability Council of Texas (ERCOT) by comparing the experimental WFIP forecast to the current short-term wind power forecast (STWPF). Four types of significant wind power ramps are employed in the study; these are based on the power change magnitude, direction, and duration. The swinging door algorithm is adopted to extract ramp events from actual and forecasted wind power time series. The results show that the experimental short-term wind power forecasts improve the accuracy of the wind power ramp forecasting, especially during the summer.

  16. Analyzing the Impact of Solar Power on Multi-Hourly Thermal Generator Ramping

    Energy Technology Data Exchange (ETDEWEB)

    Rosenkranz, Joshua-Benedict; Brancucci Martinez-Anido, Carlo; Hodge, Bri-Mathias

    2016-04-08

    Solar power generation, unlike conventional forms of electricity generation, has higher variability and uncertainty in its output because solar plant output is strongly impacted by weather. As the penetration rate of solar capacity increases, grid operators are increasingly concerned about accommodating the increased variability and uncertainty that solar power provides. This paper illustrates the impacts of increasing solar power penetration on the ramping of conventional electricity generators by simulating the operation of the Independent System Operator -- New England power system. A production cost model was used to simulate the power system under five different scenarios, one without solar power and four with increasing solar power penetrations up to 18%, in terms of annual energy. The impact of solar power is analyzed on six different temporal intervals, including hourly and multi-hourly (2- to 6-hour) ramping. The results show how the integration of solar power increases the 1- to 6-hour ramping events of the net load (electric load minus solar power). The study also analyzes the impact of solar power on the distribution of multi-hourly ramping events of fossil-fueled generators and shows increasing 1- to 6-hour ramping events for all different generators. Generators with higher ramp rates such as gas and oil turbine and internal combustion engine generators increased their ramping events by 200% to 280%. For other generator types--including gas combined-cycle generators, coal steam turbine generators, and gas and oil steam turbine generators--more and higher ramping events occurred as well for higher solar power penetration levels.

  17. Optimized Swinging Door Algorithm for Wind Power Ramp Event Detection: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Mingjian; Zhang, Jie; Florita, Anthony R.; Hodge, Bri-Mathias; Ke, Deping; Sun, Yuanzhang

    2015-08-06

    Significant wind power ramp events (WPREs) are those that influence the integration of wind power, and they are a concern to the continued reliable operation of the power grid. As wind power penetration has increased in recent years, so has the importance of wind power ramps. In this paper, an optimized swinging door algorithm (SDA) is developed to improve ramp detection performance. Wind power time series data are segmented by the original SDA, and then all significant ramps are detected and merged through a dynamic programming algorithm. An application of the optimized SDA is provided to ascertain the optimal parameter of the original SDA. Measured wind power data from the Electric Reliability Council of Texas (ERCOT) are used to evaluate the proposed optimized SDA.

  18. Geostationary Operational Environmental Satellite (GOES) Gyro Temperature Model

    Science.gov (United States)

    Rowe, J. N.; Noonan, C. H.; Garrick, J.

    1996-01-01

    The geostationary Operational Environmental Satellite (GOES) 1/M series of spacecraft are geostationary weather satellites that use the latest in weather imaging technology. The inertial reference unit package onboard consists of three gyroscopes measuring angular velocity along each of the spacecraft's body axes. This digital integrating rate assembly (DIRA) is calibrated and used to maintain spacecraft attitude during orbital delta-V maneuvers. During the early orbit support of GOES-8 (April 1994), the gyro drift rate biases exhibited a large dependency on gyro temperature. This complicated the calibration and introduced errors into the attitude during delta-V maneuvers. Following GOES-8, a model of the DIRA temperature and drift rate bias variation was developed for GOES-9 (May 1995). This model was used to project a value of the DIRA bias to use during the orbital delta-V maneuvers based on the bias change observed as the DIRA warmed up during the calibration. The model also optimizes the yaw reorientation necessary to achieve the correct delta-V pointing attitude. As a result, a higher accuracy was achieved on GOES-9 leading to more efficient delta-V maneuvers and a propellant savings. This paper summarizes the: Data observed on GOES-8 and the complications it caused in calibration; DIRA temperature/drift rate model; Application and results of the model on GOES-9 support.

  19. Ultra high temperature diffusion apparatus and operating procedures

    Energy Technology Data Exchange (ETDEWEB)

    Wyrick, S.B.

    1985-11-15

    It is the purpose of this paper to present an experimental apparatus which is capable of measuring diffusion coefficients of interdiffusing gases in the temperature range 300K to 2500K. Because of the high temperatures which will be encountered, a special alloy of tantalum (T-111) is used to house the diffusion process. This T-111 diffusion cell is heated via radiation heat from a tungsten heating element powered by a Saban saturable reactor power supply. The diffusion cell heating element are encased in a nickel-plated copper cooling can. This entire assembly is enclosed in an Ultek vacuum chamber to prevent oxidation of the diffusion cell. This report covers the construction and calibration of the diffusion cell, details of the gas loading and sampling system, and complete information on the components required to operate the vacuum furnace. Thus far, several experiments have been run in the temperature range 600K to 800K and the resulting diffusion coefficients agree fairly well with previously published values. 21 refs., 9 figs., 4 tabs.

  20. Development of high-temperature superconducting filters operating at temperatures above 90 K

    Institute of Scientific and Technical Information of China (English)

    XIA HouHai; ZHOU ChunXia; ZUO Tao; HE Ming; JI Lu; ZHOU TieGe; ZHAO XinJie; FANG Lan; YAN ShaoLin

    2009-01-01

    This paper represents the development of a high temperature superconducting (HTS) filter, the highest operating temperature of which is up to 93 K. The filter is designed for S band with 4% fractional bandwidth and fabricated using thallium-barium-calcium-copper oxide (Tl_2Ba_2CaCu_2O_8) thin films. At 93 K, the measurements of the filter show that the insertion loss in the passband is less than 0.22 dB, the return loss is better than 20 dB, and the out-of-band rejection is more than 80 dB. The analysis on the characteristics of the filter operating at different temperatures shows that the filter can work well at temperatures around 90 K. The temperature of 93 K is the highest among the previous reports for HTS filters. The result reported in this paper is significant for HTS filters to be used in the field of microwave communication requiring high sensitivity.

  1. CFB cyclones at high temperature: Operational results and design assessment

    Institute of Scientific and Technical Information of China (English)

    Raf Dewil; Jan Baeyens; Bart Caerts

    2008-01-01

    Pressure drop and cut size measurements are reported for a full scale cyclone operating within a 58 MWth CFB-combustor unit at 775℃.The paper reviews the vast number of equations to calculate the pressure drop and separation efficiency of cyclones, generally for operation at ambient temperature and at low Cs[0.5]. None of the literature correlations predicts the pressure drop with a fair accuracy within the range of experimental operating conditions. The cut size d50 can be estimated using direct empirical methods or using the Stokes number, Stk50. Both methods were used to compare measured and predicted values of d50. With the exception of Muschelknautz and Krambrock, none of the equations made accurate predictions.Finally, an alternative method to determine the friction factor of the pressure drop equation (Euler number, Eu) and of the cut size is proposed. The Eu number is determined from the geometry of common cyclones, and the derived value of Stk50 defines more accurate cut sizes. The remaining discrepancy of less than 5%, when compared with the measured values, is tentatively explained in terms of a reduced cyclone diameter due to the solids layer formed near its wall. Further measurements, mostly using positron emission particle tracking, elucidate the particle motion in the cyclone and both tracking results and the influence of the particle movement on Eu and Stk50 will be discussed in a follow-up paper.

  2. Refractive Secondary Solar Concentrator Demonstrated High-Temperature Operation

    Science.gov (United States)

    Wong, Wayne A.

    2002-01-01

    Space applications that utilize solar thermal energy--such as electric power conversion systems, thermal propulsion systems, and furnaces--require highly efficient solar concentration systems. The NASA Glenn Research Center is developing the refractive secondary concentrator, which uses refraction and total internal reflection to efficiently concentrate and direct solar energy. When used in combination with advanced lightweight primary concentrators, such as inflatable thin films, the refractive secondary concentrator enables very high system concentration ratios and very high temperatures. Last year, Glenn successfully demonstrated a secondary concentrator throughput efficiency of 87 percent, with a projected efficiency of 93 percent using an antireflective coating. Building on this achievement, Glenn recently successfully demonstrated high-temperature operation of the secondary concentrator when it was used to heat a rhenium receiver to 2330 F. The high-temperature demonstration of the concentrator was conducted in Glenn's 68-ft long Tank 6 thermal vacuum facility equipped with a solar simulator. The facility has a rigid panel primary concentrator that was used to concentrate the light from the solar simulator onto the refractive secondary concentrator. NASA Marshall Space Flight Center provided a rhenium cavity, part of a solar thermal propulsion engine, to serve as the high-temperature receiver. The prototype refractive secondary concentrator, measuring 3.5 in. in diameter and 11.2 in. long, is made of single-crystal sapphire. A water-cooled splash shield absorbs spillage light outside of the 3.5-in. concentrator aperture. Multilayer foil insulation composed of tungsten, molybdenum, and niobium is used to minimize heat loss from the hightemperature receiver. A liquid-cooled canister calorimeter is used to measure the heat loss through the multilayer foil insulation.

  3. Review of Wind Energy Forecasting Methods for Modeling Ramping Events

    Energy Technology Data Exchange (ETDEWEB)

    Wharton, S; Lundquist, J K; Marjanovic, N; Williams, J L; Rhodes, M; Chow, T K; Maxwell, R

    2011-03-28

    Tall onshore wind turbines, with hub heights between 80 m and 100 m, can extract large amounts of energy from the atmosphere since they generally encounter higher wind speeds, but they face challenges given the complexity of boundary layer flows. This complexity of the lowest layers of the atmosphere, where wind turbines reside, has made conventional modeling efforts less than ideal. To meet the nation's goal of increasing wind power into the U.S. electrical grid, the accuracy of wind power forecasts must be improved. In this report, the Lawrence Livermore National Laboratory, in collaboration with the University of Colorado at Boulder, University of California at Berkeley, and Colorado School of Mines, evaluates innovative approaches to forecasting sudden changes in wind speed or 'ramping events' at an onshore, multimegawatt wind farm. The forecast simulations are compared to observations of wind speed and direction from tall meteorological towers and a remote-sensing Sound Detection and Ranging (SODAR) instrument. Ramping events, i.e., sudden increases or decreases in wind speed and hence, power generated by a turbine, are especially problematic for wind farm operators. Sudden changes in wind speed or direction can lead to large power generation differences across a wind farm and are very difficult to predict with current forecasting tools. Here, we quantify the ability of three models, mesoscale WRF, WRF-LES, and PF.WRF, which vary in sophistication and required user expertise, to predict three ramping events at a North American wind farm.

  4. Operational forecasting of daily temperatures in the Valencia Region. Part II: minimum temperatures in winter.

    Science.gov (United States)

    Gómez, I.; Estrela, M.

    2009-09-01

    Extreme temperature events have a great impact on human society. Knowledge of minimum temperatures during winter is very useful for both the general public and organisations whose workers have to operate in the open, e.g. railways, roadways, tourism, etc. Moreover, winter minimum temperatures are considered a parameter of interest and concern since persistent cold-waves can affect areas as diverse as public health, energy consumption, etc. Thus, an accurate forecasting of these temperatures could help to predict cold-wave conditions and permit the implementation of strategies aimed at minimizing the negative effects that low temperatures have on human health. The aim of this work is to evaluate the skill of the RAMS model in determining daily minimum temperatures during winter over the Valencia Region. For this, we have used the real-time configuration of this model currently running at the CEAM Foundation. To carry out the model verification process, we have analysed not only the global behaviour of the model for the whole Valencia Region, but also its behaviour for the individual stations distributed within this area. The study has been performed for the winter forecast period from 1 December 2007 - 31 March 2008. The results obtained are encouraging and indicate a good agreement between the observed and simulated minimum temperatures. Moreover, the model captures quite well the temperatures in the extreme cold episodes. Acknowledgement. This work was supported by "GRACCIE" (CSD2007-00067, Programa Consolider-Ingenio 2010), by the Spanish Ministerio de Educación y Ciencia, contract number CGL2005-03386/CLI, and by the Regional Government of Valencia Conselleria de Sanitat, contract "Simulación de las olas de calor e invasiones de frío y su regionalización en la Comunidad Valenciana" ("Heat wave and cold invasion simulation and their regionalization at Valencia Region"). The CEAM Foundation is supported by the Generalitat Valenciana and BANCAIXA (Valencia

  5. Operational forecasting of daily temperatures in the Valencia Region. Part I: maximum temperatures in summer.

    Science.gov (United States)

    Gómez, I.; Estrela, M.

    2009-09-01

    Extreme temperature events have a great impact on human society. Knowledge of summer maximum temperatures is very useful for both the general public and organisations whose workers have to operate in the open, e.g. railways, roadways, tourism, etc. Moreover, summer maximum daily temperatures are considered a parameter of interest and concern since persistent heat-waves can affect areas as diverse as public health, energy consumption, etc. Thus, an accurate forecasting of these temperatures could help to predict heat-wave conditions and permit the implementation of strategies aimed at minimizing the negative effects that high temperatures have on human health. The aim of this work is to evaluate the skill of the RAMS model in determining daily maximum temperatures during summer over the Valencia Region. For this, we have used the real-time configuration of this model currently running at the CEAM Foundation. To carry out the model verification process, we have analysed not only the global behaviour of the model for the whole Valencia Region, but also its behaviour for the individual stations distributed within this area. The study has been performed for the summer forecast period of 1 June - 30 September, 2007. The results obtained are encouraging and indicate a good agreement between the observed and simulated maximum temperatures. Moreover, the model captures quite well the temperatures in the extreme heat episodes. Acknowledgement. This work was supported by "GRACCIE" (CSD2007-00067, Programa Consolider-Ingenio 2010), by the Spanish Ministerio de Educación y Ciencia, contract number CGL2005-03386/CLI, and by the Regional Government of Valencia Conselleria de Sanitat, contract "Simulación de las olas de calor e invasiones de frío y su regionalización en la Comunidad Valenciana" ("Heat wave and cold invasion simulation and their regionalization at Valencia Region"). The CEAM Foundation is supported by the Generalitat Valenciana and BANCAIXA (Valencia, Spain).

  6. Development of ramp-flat structures during Aegean extension

    Science.gov (United States)

    Brun, Jean-Pierre; Sokoutis, Dimitrios

    2014-05-01

    Low-angle extensional shear is frequently observed in the Aegean metamorphic rocks. This deformation is commonly interpreted as being related to detachment at crustal scale, yet it often corresponds to ramp-flat extensional systems that, at many places, control the deposition of Neogene sedimentary basins. From a mechanical point of view, the development of a ramp-flat structure requires the presence of weak layers that can be activated as décollement between stronger rocks units. In the Aegean, the décollement generally develops within the upper brittle crust (i.e. with temperatures lower than about 400°C) that consists in recently exhumed metamorphic rocks. The process by which, these layers become weak enough to form efficient décollements in extension is somewhat intriguing and not well understood. In this contribution we examine the particular case of ramp-flat structures of the Southern Rhodope Core Complex that controlled the deposition of late Miocene to Pleistocene sediments in continental and marine basins. Field evidence is used to argue that the décollement corresponds to marble layers that separate orthogneisses at 2-3 km depth within an upper brittle crust whose thickness is around 5 km. Field observation and stable isotope measurements suggest that the ramp-flat structure observed on the island of Thassos occurred in a marble unit rich in fluids at a temperature of around 200°C. Using laboratory experiments, we explore the geometry of extensional structures (fault systems, rollovers, piggy-back basins…) that can develop at crustal-scale as a function of: i) décollement depth and dip, ii) number of décollements, and iii) strength contrast, between the décollement and overlying strong units. The results are compared with the situation observed in the Southern Rhodope Core Complex. We are convinced that the principles of ramp-flat extension discussed here have a strong potential of application in many other orogenic domains affected by large

  7. Micro-Ramps for Hypersonic Flow Control

    Directory of Open Access Journals (Sweden)

    Konstantinos Kontis

    2012-04-01

    Full Text Available Shock/boundary layer interaction (SBLI is an undesirable phenomenon, occurring in high-speed propulsion systems. The conventional method to manipulate and control SBLI is using a bleed system that involves the removal of a certain amount of mass of the inlet flow to control boundary layer separation. However, the system requires a larger nacelle to compensate the mass loss, larger nacelles contribute to additional weight and drag and reduce the overall performance. This study investigates a novel type of flow control device called micro-ramps, a part of the micro vortex generators (VGs family that intends to replace the bleed technique. Micro-ramps produce pairs of counter-rotating streamwise vortices, which help to suppress SBLI and reduce the chances of flow separation. Experiments were done at Mach 5 with two micro-ramp models of different sizes. Schlieren photography, surface flow visualization and infrared thermography were used in this investigation. The results revealed the detailed flow characteristics of the micro-ramp, such as the primary and secondary vortices. This helps us to understand the overall flow physics of micro-ramps in hypersonic flow and their application for SBLI control.

  8. Extrapolating power-ramp performance criteria for current and advanced CANDU fuels

    Energy Technology Data Exchange (ETDEWEB)

    Tayal, M.; Chassie, G.G

    2000-06-01

    To improve the precision and accuracy of power-ramp performance criteria for high-burnup fuel, we have examined in-reactor fuel performance data as well as out-reactor test data. The data are consistent with some of the concepts used in the current formulations for defining fuel failure thresholds, such as size of power-ramp and extent of burnup. Our review indicates that there is a need to modify some other aspects of the current formulations; therefore, a modified formulation is presented in this paper. The improvements mainly concern corrodent concentration and its relationships with threshold stress for failure. The new formulation is consistent with known and expected trends such as strength of Zircaloy in corrosive environment, timing of the release of fission products to the pellet-to-sheath gap, CANLUB coating, and fuel burnup. Because of the increased precision and accuracy, the new formulation is better able to identify operational regimes that are at risk of power-ramp failures; this predictive ability provides enhanced protection to fuel against power-ramp defects. At die same time, by removing unnecessary conservatisms in other areas, the new formulation permits a greater range of defect-free operational envelope as well as larger operating margins in regions that are, in fact, not prone to power-ramp failures. (author)

  9. Microprocessor-controlled, programmable ramp voltage generator

    Energy Technology Data Exchange (ETDEWEB)

    Hopwood, J.

    1978-11-01

    A special-purpose voltage generator has been developed for driving the quadrupole mass filter of a residual gas analyzer. The generator is microprocessor-controlled with desired ramping parameters programmed by setting front-panel digital thumb switches. The start voltage, stop voltage, and time of each excursion are selectable. A maximum of five start-stop levels may be pre-selected for each program. The ramp voltage is 0 to 10 volts with sweep times from 0.1 to 999.99 seconds.

  10. Quality control methods for KOOS operational sea surface temperature products

    Institute of Scientific and Technical Information of China (English)

    YANG Chansu; KIM Sunhwa

    2016-01-01

    Sea surface temperature SST obtained from the initial version of the Korea Operational Oceanographic System (KOOS) SST satellite have low accuracy during summer and daytime. This is attributed to the diurnal warming effect. Error estimation of SST data must be carried out to use the real-time forecasting numerical model of the KOOS. This study suggests two quality control methods for the KOOS SST system. To minimize the diurnal warming effect, SSTs of areas where wind speed is higher than 5 m/s were used. Depending on the wind threshold value, KOOS SST data for August 2014 were reduced by 0.15°C. Errors in SST data are considered to be a combination of random, sampling, and bias errors. To estimate bias error, the standard deviation of bias between KOOS SSTs and climatology SSTs were used. KOOS SST data yielded an analysis error standard deviation value similar to OSTIA and NOAA NCDC (OISST) data. The KOOS SST shows lower random and sampling errors with increasing number of observations using six satellite datasets. In further studies, the proposed quality control methods for the KOOS SST system will be applied through more long-term case studies and comparisons with other SST systems.

  11. State-space approach to vibration of gold nano-beam induced by ramp type heating

    Institute of Scientific and Technical Information of China (English)

    Hamdy M Youssef; Khaled A Elsibai

    2010-01-01

    In the nanoscale beam, two effects become domineering. One is the non-Fourier effect in heat conduction and the other is the coupling effect between temperature and strain rate. In the present study, a generalized solution for the generalized thermoelastic vibration of gold nano-beam resonator induced by ramp type heating is developed. The solution takes into account the above two effects. State-space and Laplace transform methods are used to determine the lateral vibration, the temperature, the displacement, the stress and the strain energy of the beam. The effects of the relaxation time and the ramping time parameters have been studied.

  12. Operating temperatures of open-rack installed photovoltaic inverters

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Z.; Wang, L.; Kurtz, S.; Wu, J.; Quan, P.; Sorensen, R.; Liu, S.; Bai, J. B.; Zhu, Z. W.

    2016-11-01

    This paper presents a model for evaluating the heat-sink and component temperatures of open-rack installed photovoltaic inverters. These temperatures can be used for predicting inverter reliability. Inverter heat-sink temperatures were measured for inverters connected to three grid-connected PV (photovoltaic) test systems in Golden, Colorado, US. A model is proposed for calculating the inverter heat-sink temperature based on the ambient temperature, the ratio of the consumed power to the rated power of the inverter, and the measured wind speed. To verify and study this model, more than one year of inverter DC/AC power, irradiance, wind speed, and heat sink temperature rise data were collected and analyzed. The model is shown to be accurate in predicting average inverter temperatures, but will require further refinement for prediction of transient temperatures.

  13. Paths to ignition by radio frequency heating during the B-field ramp

    Science.gov (United States)

    Myra, J. R.; Aamodt, R. E.; D'Ippolito, D. A.

    2000-05-01

    To conserve transformer volt-seconds, power to toroidal magnetic field coils, and to trigger an early transition into high confinement (H) mode, where the requirements on auxiliary power are lower, rf heating during the B-field ramp phase of ignition-class tokamaks is considered. The scheme is analyzed by modifying the usual plasma operating condition diagrams to apply to the ramp phase where the magnetic field, plasma current, and density are changing. It is shown that ion cyclotron range-of-frequencies direct electron heating during the ramp phase of IGNITOR [B. Coppi, M. Nassi, and L. E. Sugiyama, Phys. Scr. 45, 112 (1992)], as proposed by Majeski [R. Majeski, in AIP Conference Proceedings 485—Radio Frequency Power in Plasmas, Annapolis, MD (AIP, New York, 1999), p. 353], may be useful in optimizing the operating condition path to ignition.

  14. Double Ramp Loss Based Reject Option Classifier

    Science.gov (United States)

    2015-05-22

    Cao et al. (Eds.): PAKDD 2015, Part I, LNAI 9077, pp. 151–163, 2015. DOI: 10.1007/978-3-319-18038-0 12 152 N. Manwani et al. ρ is the parameter...A.: kernlab - an S4 package for kernel methods in R. Journal of Statistical Software 11(9), 1–20 ( 2004 ) Double Ramp Loss Based Reject Option

  15. Road and Street Centerlines - RAMPS_INDOT_IN: Ramp System in Indiana (Indiana Department of Transportation, Line Shapefile)

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — RAMPS_INDOT_IN is a line shapefile that contains all ramps in Indiana, provided by personnel of Indiana Department of Transportation (INDOT), Business Information...

  16. Combined Ramp and Squeeze to 6.5 TeV in the LHC

    CERN Document Server

    Solfaroli Camillocci, Matteo; Tomás, Rogelio; Wenninger, Jorg

    2016-01-01

    The cycle of the LHC is composed of an energy ramp followed by a betatron squeeze, needed to reduce the beta- star value in the interaction points. Since Run 1, studies have been carried out to investigate the feasibility of combining the two operations, thus considerably reducing the duration of the operational cycle. In Run 2, the LHC is operating at the energy of 6.5 TeV that requires a much longer cycle than that of Run 1. Therefore, the performance gains from a Combined Ramp and Squeeze (CRS) is more interesting. Merging the energy ramp and the betatron squeeze could result in a gain of several minutes for each LHC cycle. With increasing maturity of LHC operation, it is now possible to envisage more complex beam manipulations; this paper describes the first machine experiment with beam, aiming at validating the combination of ramp and squeeze, which was performed in 2015, during a machine development phase. The operation experience with the LHC run at 2.51 TeV, when CRS down to 4 meters was deployed and ...

  17. A self-focusing, high transformer ratio, collinear plasma dielectric wakefield accelerator driven by a ramped bunch train

    Science.gov (United States)

    Sotnikov, Gennadij V.; Marshall, Thomas C.; Shchelkunov, Sergey V.; Hirshfield, Jay L.

    2017-03-01

    New results of studies of wakefield excitation by a ramped bunch train in a collinear, single-channel dielectriclined THz-wakefield accelerator structure that is filled with a low-temperature plasma are presented. A novel ramped train of drive bunches, together with plasma filling part of the transport channel, makes possible substantial improvement of the transformer ratio of the multimode collinear device to 6:1 while the plasma could stabilize the transverse motion of the drive and witness bunches.

  18. X-ray diffraction of molybdenum under ramp compression to 1 TPa

    Science.gov (United States)

    Wang, Jue; Coppari, Federica; Smith, Raymond F.; Eggert, Jon H.; Lazicki, Amy E.; Fratanduono, Dayne E.; Rygg, J. Ryan; Boehly, Thomas R.; Collins, Gilbert W.; Duffy, Thomas S.

    2016-09-01

    Molybdenum (Mo) is a transition metal with a wide range of technical applications. There has long been strong interest in its high-pressure behavior, and it is often used as standard for high-pressure experiments. Combining powder x-ray diffraction and dynamic ramp compression, structural and equation of state data were collected for solid Mo to 1 TPa (10 Mbar). Diffraction results are consistent with Mo remaining in the body-centered-cubic structure into the TPa regime. Stress-density data show that Mo under ramp loading is less compressible than the room-temperature isotherm but more compressible than the single-shock Hugoniot.

  19. Effect of Air Velocity on Thermal Comfort under Thermal Environment Ramp Changing

    Institute of Scientific and Technical Information of China (English)

    嵇赟喆; 涂光备; 孙琳

    2004-01-01

    Set points of the indoor air temperature and relative humidity in short-term staying location were studied. In this condition, the thermal reaction of human body varied with the ramp changes of the environmental thermal parameters.The change rules of about 60 subjects'thermal reaction to the ramp change of environment were surveyed, and the effect of air movement on the thermal reaction during transient condition was considered by using a questionnaire. With the experimental results and research findings under stable condition, a way to set environmental parameters of short-time staying location was recommended.

  20. A Method for more specific Simulation of Operative Temperature in Thermal Analysis Programmes

    DEFF Research Database (Denmark)

    Christensen, Jørgen Erik

    2008-01-01

    Simulation of energy consumption of buildings on hourly basis is closely connected to the thermal indoor climate. The operative temperature can be used as a simple measure for thermal environment. The operative temperature is a function of the air temperature, the mean radiant temperature and the...... for calculating the angular factor and shows how a matrix solution for the angular factor can easily be implemented in programs for dynamic building thermal analysis.......Simulation of energy consumption of buildings on hourly basis is closely connected to the thermal indoor climate. The operative temperature can be used as a simple measure for thermal environment. The operative temperature is a function of the air temperature, the mean radiant temperature...

  1. Solar Power Ramp Events Detection Using an Optimized Swinging Door Algorithm: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Mingjian; Zhang, Jie; Florita, Anthony; Hodge, Bri-Mathias; Ke, Deping; Sun, Yuanzhang

    2015-08-07

    Solar power ramp events (SPREs) are those that significantly influence the integration of solar power on non-clear days and threaten the reliable and economic operation of power systems. Accurately extracting solar power ramps becomes more important with increasing levels of solar power penetrations in power systems. In this paper, we develop an optimized swinging door algorithm (OpSDA) to detection. First, the swinging door algorithm (SDA) is utilized to segregate measured solar power generation into consecutive segments in a piecewise linear fashion. Then we use a dynamic programming approach to combine adjacent segments into significant ramps when the decision thresholds are met. In addition, the expected SPREs occurring in clear-sky solar power conditions are removed. Measured solar power data from Tucson Electric Power is used to assess the performance of the proposed methodology. OpSDA is compared to two other ramp detection methods: the SDA and the L1-Ramp Detect with Sliding Window (L1-SW) method. The statistical results show the validity and effectiveness of the proposed method. OpSDA can significantly improve the performance of the SDA, and it can perform as well as or better than L1-SW with substantially less computation time.

  2. Probabilistic Swinging Door Algorithm as Applied to Photovoltaic Power Ramping Event Detection

    Energy Technology Data Exchange (ETDEWEB)

    Florita, Anthony; Zhang, Jie; Brancucci Martinez-Anido, Carlo; Hodge, Bri-Mathias; Cui, Mingjian

    2015-10-02

    Photovoltaic (PV) power generation experiences power ramping events due to cloud interference. Depending on the extent of PV aggregation and local grid features, such power variability can be constructive or destructive to measures of uncertainty regarding renewable power generation; however, it directly influences contingency planning, production costs, and the overall reliable operation of power systems. For enhanced power system flexibility, and to help mitigate the negative impacts of power ramping, it is desirable to analyze events in a probabilistic fashion so degrees of beliefs concerning system states and forecastability are better captured and uncertainty is explicitly quantified. A probabilistic swinging door algorithm is developed and presented in this paper. It is then applied to a solar data set of PV power generation. The probabilistic swinging door algorithm builds on results from the original swinging door algorithm, first used for data compression in trend logging, and it is described by two uncertain parameters: (i) e, the threshold sensitivity to a given ramp, and (ii) s, the residual of the piecewise linear ramps. These two parameters determine the distribution of ramps and capture the uncertainty in PV power generation.

  3. Lattice-ramp-induced dynamics in an interacting Bose-Bose mixture

    NARCIS (Netherlands)

    J. Wernsdorfer; M. Snoek; W. Hofstetter

    2010-01-01

    We investigate a bosonic quantum gas consisting of two interacting species in an optical lattice at zero and finite temperature. The equilibrium properties and dynamics of this system are obtained by means of the Gutzwiller mean-field method. In particular we model recent experiments where the ramp-

  4. Numerical solution of shock and ramp compression for general material properties

    Energy Technology Data Exchange (ETDEWEB)

    Swift, D C

    2009-01-28

    A general formulation was developed to represent material models for applications in dynamic loading. Numerical methods were devised to calculate response to shock and ramp compression, and ramp decompression, generalizing previous solutions for scalar equations of state. The numerical methods were found to be flexible and robust, and matched analytic results to a high accuracy. The basic ramp and shock solution methods were coupled to solve for composite deformation paths, such as shock-induced impacts, and shock interactions with a planar interface between different materials. These calculations capture much of the physics of typical material dynamics experiments, without requiring spatially-resolving simulations. Example calculations were made of loading histories in metals, illustrating the effects of plastic work on the temperatures induced in quasi-isentropic and shock-release experiments, and the effect of a phase transition.

  5. A historic breakthrough : Kidd Mine sets new mark for underground ramp development

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, R. [Xstrata Copper, Timmins, ON (Canada)

    2010-08-15

    This article discussed a new ventilation system installed as part of an underground ramp development at Xstrata Copper's Kidd Mine. The mine now has the deepest continual ramp from surface in the world. The down ramp is currently exhausted through raises placed on various levels and a permanent 6-metre-diameter raise exhaust system. Ventilation tests are now being conducted to optimize air flow until the breakthrough of a new exhaust raise in 2010. A set of cold stopes and a mechanical refrigeration plant are being used to cool the air. Heat will become easier to manage as the project completes changes to the ventilation set-up. Additional stopes and fresh air raises are scheduled for operation in the first quarter of 2011. The 3-year project has included contributions from several different construction companies. 2 figs.

  6. Forward modeling of shock-ramped tantalum

    Science.gov (United States)

    Brown, Justin L.; Carpenter, John H.; Seagle, Christopher T.

    2017-01-01

    Dynamic materials experiments on the Z-machine are beginning to reach a regime where traditional analysis techniques break down. Time dependent phenomena such as strength and phase transition kinetics often make the data obtained in these experiments difficult to interpret. We present an inverse analysis methodology to infer the equation of state (EOS) from velocimetry data in these types of experiments, building on recent advances in the propagation of uncertain EOS information through a hydrocode simulation. An example is given for a shock-ramp experiment in which tantalum was shock compressed to 40 GPa followed by a ramp to 80 GPa. The results are found to be consistent with isothermal compression and Hugoniot data in this regime.

  7. Space Electronics Operating at High Temperatures and Radiation Levels Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposal represents a radical revolution in Power Management & Distribution (PMAD) that addresses many of the challenges for NASA missions that will operate...

  8. Extreme High and Low Temperature Operation of the Silicon-On-Insulator Type CHT-OPA Operational Amplifier

    Science.gov (United States)

    Patterson, Richard; Hammoud, Ahmad; Elbuluk, Malik

    2008-01-01

    A new operational amplifier chip based on silicon-on-insulator technology was evaluated for potential use in extreme temperature environments. The CHT-OPA device is a low power, precision operational amplifier with rail-to-rail output swing capability, and it is rated for operation between -55 C and +225 C. A unity gain inverting circuit was constructed utilizing the CHT-OPA chip and a few passive components. The circuit was evaluated in the temperature range from -190 C to +200 C in terms of signal gain and phase shift, and supply current. The investigations were carried out to determine suitability of this device for use in space exploration missions and aeronautic applications under wide temperature incursion. Re-restart capability at extreme temperatures, i.e. power switched on while the device was soaked at extreme temperatures, was also investigated. In addition, the effects of thermal cycling under a wide temperature range on the operation of this high performance amplifier were determined. The results from this work indicate that this silicon-on-insulator amplifier chip maintained very good operation between +200 C and -190 C. The limited thermal cycling had no effect on the performance of the amplifier, and it was able to re-start at both -190 C and +200 C. In addition, no physical degradation or packaging damage was introduced due to either extreme temperature exposure or thermal cycling. The good performance demonstrated by this silicon-on-insulator operational amplifier renders it a potential candidate for use in space exploration missions or other environments under extreme temperatures. Additional and more comprehensive characterization is, however, required to establish the reliability and suitability of such devices for long term use in extreme temperature applications.

  9. Research on recognition of ramp angle based on transducer

    Directory of Open Access Journals (Sweden)

    Wenhao GU

    2015-12-01

    Full Text Available Focusing on the recognition of ramp angle, the relationship between the signal of vehicle transducer and real ramp angle is studied. The force change of vehicle on the ramp, and the relationship between the body tilt angle and front and rear suspension scale is discussed. According to the suspension and tire deformation, error angle of the ramp angle is deduced. A mathematical model is established with Matlab/Simulink and used for simulation to generate error curve of ramp angle. The results show that the error angle increases with the increasing of the ramp angle, and the limit value can reach 6.5%, while the identification method can effectively eliminate this error, and enhance the accuracy of ramp angle recognition.

  10. Performance of a spacecraft DC-DC converter breadboard modified for low temperature operation

    Science.gov (United States)

    Gerber, Scott S.; Stell, Chris; Patterson, Richard; Ray, Biswajit

    1996-01-01

    A 1OW 3OV/5.OV push-pull dc-dc converter breadboard, designed by the Jet Propulsion Laboratory (JPL) with a +50 C to +5 C operating range for the Cassini space probe, was characterized for lower operating temperatures. The breadboard converter which failed to operate for temperatures below -125 C was then modified to operate at temperatures approaching that of liquid nitrogen (LN2). Associated with this low operating temperature range (greater than -196 C) was a variety of performance problems such as significant change in output voltage, converter switching instability, and failure to restart at temperatures below -154 C. An investigation into these problems yielded additional modifications to the converter which improved low temperature performance even further.

  11. Operational Temperature Effect on Positioning Accuracy of a Single-Axial Moving Carrier

    Directory of Open Access Journals (Sweden)

    Kun-Ying Li

    2017-04-01

    Full Text Available This study investigated the ambient environmental temperature effect on the positioning accuracy of a periodically-moving carrier. The moving carrier was operated in an environmental chamber in which the operational temperature could be controlled by an air conditioning system. Different operational temperature modes, including a stable environment, a rise in temperature, a decline in temperature, summer daytime hours, and winter nighttime hours in terms of seasonal climate change in Taiwan, were generated within the environmental chamber by an air conditioning system to investigate the operational temperature’s effect on positioning accuracy. From the experimental measurements of a periodically-moving carrier, it is found that the operational temperature conditions can significantly affect the positioning accuracy of the moving carrier, especially in the case of an operational temperature decline. Under stable operational conditions, the positioning accuracy of the moving carrier can be considerably improved. In comparison to the case of an operational temperature decline, the positioning accuracy improvement can reach 29.6%. Moreover, the effect of the temperature distributions within the chamber on the positioning accuracy was further investigated. It was found that, with a parallel flow pattern in the chamber, the positioning accuracy can be further enhanced.

  12. Low-temperature operation of a Buck DC/DC converter

    Science.gov (United States)

    Ray, Biswajit; Gerber, Scott S.; Patterson, Richard L.; Myers, Ira T.

    1995-01-01

    Low-temperature (77 K) operation of a 42/28 V, 175 W, 50 kHz PWM Buck DC/DC converter designed with commercially available components is reported. Overall, the converter losses decreased at 77 K compared to room temperature operation. A full-load efficiency of 97 percent was recorded at liquid-nitrogen temperature, compared to 95.8 percent at room temperature. Power MOSFET operation improved significantly where as the output rectifier operation deteriorated at low-temperature. The performance of the output filter inductor and capacitor did not change significantly at 77 K compared to room temperature performance. It is possible to achieve high-density and high efficiency power conversion at low-temperatures due to improved electronic, electrical and thermal properties of materials.

  13. Lithium Batteries and Supercapacitors Capable of Operating at Low Temperatures for Planetary Exploration

    Science.gov (United States)

    Smart, M. C.; Ratnakumar, B. V.; West, W. C.; Brandon, E. J.

    2012-01-01

    Demonstrated improved performance with wide operating temperature electrolytes containing ester co - solvents (i.e., methyl propionate and ethyl butyrate) in a number of prototype cells: center dot Successfully scaled up low temperature technology to 12 Ah size prismatic Li - ion cells (Quallion, LCC), and demonstrated good performance down to - 60 o C. center dot Demonstrated wide operating temperature range performance ( - 60 o to +60 o C) in A123 Systems LiFePO 4 - based lithium - ion cells containing methyl butyrate - based low temperature electrolytes. These systems were also demonstrated to have excellent cycle life performance at ambient temperatures, as well as the ability to be cycled up to high temperatures.

  14. Thermal measurement. Nanoscale temperature mapping in operating microelectronic devices.

    Science.gov (United States)

    Mecklenburg, Matthew; Hubbard, William A; White, E R; Dhall, Rohan; Cronin, Stephen B; Aloni, Shaul; Regan, B C

    2015-02-06

    Modern microelectronic devices have nanoscale features that dissipate power nonuniformly, but fundamental physical limits frustrate efforts to detect the resulting temperature gradients. Contact thermometers disturb the temperature of a small system, while radiation thermometers struggle to beat the diffraction limit. Exploiting the same physics as Fahrenheit's glass-bulb thermometer, we mapped the thermal expansion of Joule-heated, 80-nanometer-thick aluminum wires by precisely measuring changes in density. With a scanning transmission electron microscope and electron energy loss spectroscopy, we quantified the local density via the energy of aluminum's bulk plasmon. Rescaling density to temperature yields maps with a statistical precision of 3 kelvin/hertz(-1/2), an accuracy of 10%, and nanometer-scale resolution. Many common metals and semiconductors have sufficiently sharp plasmon resonances to serve as their own thermometers. Copyright © 2015, American Association for the Advancement of Science.

  15. Principal Quasi-Isentropes of Several Materials to Multi-Megabar Pressure from Analysis of Magnetically Driven Ramp Compression Data

    Science.gov (United States)

    Davis, Jean-Paul; Martin, Matthew; Knudson, Marcus

    2011-06-01

    Quasi-isentropic ramp-wave experiments promise accurate equation-of-state (EOS) data in the solid phase at relatively low temperatures and multimegabar pressures. In this range of pressure, isothermal diamond-anvil techniques have limited pressure accuracy due to reliance on theoretical EOS of calibration standards, thus accurate quasi-isentropic compression data would help immensely in constraining EOS models. Multi-megabar ramp compression experiments using the Z Machine at Sandia as a magnetic drive with stripline targets have been performed on tantalum, copper, gold, beryllium, molybdenum, and aluminum metals as well as lithium fluoride crystal. Much of the data from these experiments are analyzed using a single-sample inverse Lagrangian approach. This technique, and the quantification of its uncertainties, will be described in detail. Results will be presented for selected materials, with comparisons to independently developed EOS. *Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  16. High accuracy magnetic field sensors with wide operation temperature range

    Science.gov (United States)

    Vasil'evskii, I. S.; Vinichenko, A. N.; Rubakin, D. I.; Bolshakova, I. A.; Kargin, N. I.

    2016-10-01

    n+InAs(Si) epitaxial thin films heavily doped by silicon and Hall effect magnetic field sensors based on this structures have been fabricated and studied. We have demonstrated the successful formation of highly doped InAs thin films (∼100 nm) with the different intermediate layer arrangement and appropriate electron mobility values. Hall sensors performance parameters have been measured in wide temperature range. Obtained sensitivity varied from 1 to 40 Ω/T, while the best linearity and lower temperature coefficient have been found in the higher doped samples with lower electron mobility. We attribute this to the electron system degeneracy and decreased phonon contribution to electron mobility and resistance.

  17. Silicon solar cell monitors high temperature furnace operation

    Science.gov (United States)

    Zellner, G. J.

    1968-01-01

    Silicon solar cell, attached to each viewpoint, monitors that incandescent emission from the hot interior of a furnace without interfering with the test assembly or optical pyrometry during the test. This technique can provide continuous indication of hot spots or provide warning of excessive temperatures in cooler regions.

  18. Operational efficiency of ballast water biocides at low water temperatures

    NARCIS (Netherlands)

    Kaag, N.H.B.M.; Sneekes, A.C.

    2015-01-01

    In the period 2013-2015 the effect of two biocides used for the treatment of ballast water has been evaluated at low ambient temperatures. Peraclean® Ocean and sodium hypochlorite were used as biocides. Most of the tests were conducted during winter and early spring at the laboratories of IMARES in

  19. Electrolytes for Wide Operating Temperature Lithium-Ion Cells

    Science.gov (United States)

    Smart, Marshall C. (Inventor); Bugga, Ratnakumar V. (Inventor)

    2016-01-01

    Provided herein are electrolytes for lithium-ion electrochemical cells, electrochemical cells employing the electrolytes, methods of making the electrochemical cells and methods of using the electrochemical cells over a wide temperature range. Included are electrolyte compositions comprising a lithium salt, a cyclic carbonate, a non-cyclic carbonate, and a linear ester and optionally comprising one or more additives.

  20. Operational experience with room temperature continuous wave accelerator structures

    Science.gov (United States)

    Alimov, A. S.; Ishkhanov, B. S.; Piskarev, I. M.; Shvedunov, V. I.; Tiunov, A. V.

    1993-05-01

    The paper reports the results of the computer simulation of parameters of the on-axis coupled accelerator structure for the continuous wave racetrack microtron. The operational experience with the accelerating sections on the basis of the on-axis coupled structure is described.

  1. CdZnTe room-temperature semiconductor operation in liquid scintillator

    CERN Document Server

    Stewart, D Y

    2008-01-01

    We demonstrate the first operation of CdZnTe room-temperature detectors in a liquid scintillator environment. This work follows conceptually the Heusser-type detector method of operating HPGe detectors in liquid nitrogen and liquid argon but instead for a far more practical room-temperature ensemble with the aim of achieving ultra-low background levels for radiation detection.

  2. Ge-on-Si laser operating at room temperature.

    Science.gov (United States)

    Liu, Jifeng; Sun, Xiaochen; Camacho-Aguilera, Rodolfo; Kimerling, Lionel C; Michel, Jurgen

    2010-03-01

    Monolithic lasers on Si are ideal for high-volume and large-scale electronic-photonic integration. Ge is an interesting candidate owing to its pseudodirect gap properties and compatibility with Si complementary metal oxide semiconductor technology. Recently we have demonstrated room-temperature photoluminescence, electroluminescence, and optical gain from the direct gap transition of band-engineered Ge-on-Si using tensile strain and n-type doping. Here we report what we believe to be the first experimental observation of lasing from the direct gap transition of Ge-on-Si at room temperature using an edge-emitting waveguide device. The emission exhibited a gain spectrum of 1590-1610 nm, line narrowing and polarization evolution from a mixed TE/TM to predominantly TE with increasing gain, and a clear threshold behavior.

  3. Electrolytes for Use in High Energy Lithium-Ion Batteries with Wide Operating Temperature Range

    Science.gov (United States)

    Smart, Marshall C.; Ratnakumar, B. V.; West, W. C.; Whitcanack, L. D.; Huang, C.; Soler, J.; Krause, F. C.

    2011-01-01

    Objectives of this work are: (1) Develop advanced Li -ion electrolytes that enable cell operation over a wide temperature range (i.e., -30 to +60C). (2) Improve the high temperature stability and lifetime characteristics of wide operating temperature electrolytes. (3) Improve the high voltage stability of these candidate electrolytes systems to enable operation up to 5V with high specific energy cathode materials. (4) Define the performance limitations at low and high temperature extremes, as well as, life limiting processes. (5) Demonstrate the performance of advanced electrolytes in large capacity prototype cells.

  4. Effect of operating temperature on LMFBR core performance

    Energy Technology Data Exchange (ETDEWEB)

    Noyes, R.C.; Bergeron, R.J.; di Lauro, G.F.; Kulwich, M.R.; Stuteville, D.W.

    1977-04-11

    The purpose of the study is to provide an engineering evaluation of high and low temperature LMFBR core designs. The study was conducted by C-E supported by HEDL expertise in the areas of materials behavior, fuel performance and fabrication/fuel cycle cost. The evaluation is based primarily on designs and analyses prepared by AI, GE and WARD during Phase I of the PLBR studies.

  5. Effects of temperature conditions in a gas collector on operation of primary and secondary gas coolers

    Energy Technology Data Exchange (ETDEWEB)

    Chuishchev, V.M.; Selivanova, Z.G.; Vasyuta, V.I.

    1988-04-01

    Discusses composition of coal gas leaving coke ovens and temperature effects on its composition in a gas collector and cooling systems. Effects of coal gas temperature ranging from 78 to 90 C on operation of cooling systems are analyzed: cooling intensity, naphthalene buildup, etc. Analyses show that coal gas temperature fluctuations from 80 to 90 C do not influence gas collector operation, whereas operation of primary gas coolers is influenced by gas collector operation. When coal gas temperature is reduced from 88 to 80 C intensity of coal tar accumulation increases 2 times and that of naphthalene increases 5 to 6 times. Temperature of coal gas leaving the primary coolers ranges from 35 to 40 C. Types of primary coal gas coolers, their operation and performance are comparatively evaluated. Effects of gas cooler design on efficiency of coal tar separation from coal gas are discussed. 5 refs.

  6. High Temperature Electrolysis Pressurized Experiment Design, Operation, and Results

    Energy Technology Data Exchange (ETDEWEB)

    J.E. O' Brien; X. Zhang; G.K. Housley; K. DeWall; L. Moore-McAteer

    2012-09-01

    A new facility has been developed at the Idaho National Laboratory for pressurized testing of solid oxide electrolysis stacks. Pressurized operation is envisioned for large-scale hydrogen production plants, yielding higher overall efficiencies when the hydrogen product is to be delivered at elevated pressure for tank storage or pipelines. Pressurized operation also supports higher mass flow rates of the process gases with smaller components. The test stand can accommodate planar cells with dimensions up to 8.5 cm x 8.5 cm and stacks of up to 25 cells. It is also suitable for testing other cell and stack geometries including tubular cells. The pressure boundary for these tests is a water-cooled spool-piece pressure vessel designed for operation up to 5 MPa. Pressurized operation of a ten-cell internally manifolded solid oxide electrolysis stack has been successfully demonstrated up 1.5 MPa. The stack is internally manifolded and operates in cross-flow with an inverted-U flow pattern. Feed-throughs for gas inlets/outlets, power, and instrumentation are all located in the bottom flange. The entire spool piece, with the exception of the bottom flange, can be lifted to allow access to the internal furnace and test fixture. Lifting is accomplished with a motorized threaded drive mechanism attached to a rigid structural frame. Stack mechanical compression is accomplished using springs that are located inside of the pressure boundary, but outside of the hot zone. Initial stack heatup and performance characterization occurs at ambient pressure followed by lowering and sealing of the pressure vessel and subsequent pressurization. Pressure equalization between the anode and cathode sides of the cells and the stack surroundings is ensured by combining all of the process gases downstream of the stack. Steady pressure is maintained by means of a backpressure regulator and a digital pressure controller. A full description of the pressurized test apparatus is provided in this

  7. Assigning on-ramp flows to maximize capacity of highway with two on-ramps and one off-ramp in between

    Science.gov (United States)

    Chen, Jing; Lin, Lan; Jiang, Rui

    2017-01-01

    In this paper, we study the capacity of a highway with two on-ramps and one off-ramp in between by using a cellular automaton traffic flow model. We investigate how to maximize the system capacity by assigning proper traffic flow to the two on-ramps. The system phase diagram is presented and eight different regions are observed under different conditions. It is shown that in region I, in which both on-ramps are in free flow and the main road upstream of the upstream on-ramp is in congestion, assigning proper proportion of the demand to two on-ramps could maximize the system capacity. Two critical values of the off-ramp flow ratio poff have been observed. When poff p off , c 2, no demand should be assigned to the upstream on-ramp. An analytical investigation has been performed to calculate the critical values. The analytical results are in good agreement with the simulation ones.

  8. On optimum temperature conditions for operation of portable aliminum-air batteries

    Directory of Open Access Journals (Sweden)

    Vlasenko Maxim

    2017-01-01

    Full Text Available For construction of portable aluminium-air batteries (AABs for field applications the data on performance of such batteries at low temperatures are necessary. Such experimental data are presented in this article. Lower temperature limit for effective operation of portable AABs is estimated. Possibility of AABs self-heating to the desired temperature is also considered.

  9. Low-temperature thermal energy storage program annual operating plan

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, H. W.; Eissenberg, D. M.

    1979-01-01

    The LTTES program operating plans for FY 1978 are described in terms of general program objectives and the technical activities being implemented to achieve these objectives. The program structure provides emphasis on several principal thrusts; namely, seasonal thermal storage, daily/short-term thermal storage, and waste heat recovery and reuse. A work breakdown structure (WBS) organizes the efforts being carried out in-house or through subcontract within each thrust area. Fiscal data are summarized in respect to thrust area, individual efforts, and funding source.

  10. Miniature cryocooler developments for high operating temperatures at Thales Cryogenics

    Science.gov (United States)

    Arts, R.; Martin, J.-Y.; Willems, D.; Seguineau, C.; Van Acker, S.; Mullié, J. C.; Göbel, A.; Tops, M.; Le Bordays, J.; Etchanchu, T.; Benschop, A. A. J.

    2015-05-01

    In recent years there has been a drive towards miniaturized cooled IDCA solutions for low-power, low-mass, low-size products (SWaP). To support this drive, coolers are developed optimized for high-temperature, low heat load dewar-detector assemblies. In this paper, Thales Cryogenics development activities supporting SWaP are presented. Design choices are discussed and compared to various key requirements. Trade-off analysis results are presented on drive voltage, cold finger definition (length, material, diameter and sealing concept), and other interface considerations, including cold finger definition. In parallel with linear and rotary cooler options, designs for small-size high-efficiency drive electronics based on state-of-the-art architectures are presented.

  11. Heart Rate Variability as a Measure of Airport Ramp-Traffic Controllers Workload

    Science.gov (United States)

    Hayashi, Miwa; Dulchinos, Victoria Lee

    2016-01-01

    Heart Rate Variability (HRV) has been reported to reflect the person's cognitive and emotional stress levels, and may offer an objective measure of human-operator's workload levels, which are recorded continuously and unobtrusively to the task performance. The present paper compares the HRV data collected during a human-in-the-loop simulation of airport ramp-traffic control operations with the controller participants' own verbal self-reporting ratings of their workload.

  12. Evaluatie ramp in Bhopal in relatie tot arbeidsveiligheid

    OpenAIRE

    1987-01-01

    De ramp in Bhopal wordt geanalyseerd op het punt van procesveiligheid en arbeidsveiligheid. Geconcludeerd wordt dat de ramp te wijten is aan een samenloop van omstandigheden, een oorzakenstructuur. Met behulp van de TNO ongevallen - databank FACTS is geconcludeerd dat deze structuur nauwelijks afwijkt van andere ernstige ongevallen. De ramp in Bhopal was dan ook uitsluitend een uniek ongeval door de zeer fatale gevolgen. De belangrijkste lessen die uit Bhopal geleerd kunnen worden zijn ; het ...

  13. Entry ramps in the Nagel-Schreckenberg model

    DEFF Research Database (Denmark)

    Pedersen, Morten Monrad; Ruhoff, Peder Thusgaard

    2002-01-01

    This paper describes a way of including entry ramps in the Nagel-Schreckenberg traffic model. The idea is to place what are called shadow cars on a highway next to cars on entry ramps, which enables the drivers to take ramp cars into account. The model is shown to capture important real......-life traffic phenomena that have not been included in previous models. Furthermore, it is demonstrated that the desirable properties of the Nagel-Schreckenberg model are retained....

  14. Maintenance and ramp line operations safety assessment (M&R LOSA: using a tested approach for risk management and safety enhancement = Avaliação de segurança nas operações de linha em serviços de rampa e de manutenção (M&R LOSA: utilizando uma abordagem testada para gerenciamento de riscos e aumento da segurança

    Directory of Open Access Journals (Sweden)

    Ma, Jiao

    2012-01-01

    Full Text Available The aviation industry is maturing in its preference for proactive intervention over post-accident remediation in potentially hazardous circumstances. Line Operations Safety Audits (LOSA adopts a truly proactive and predictive strategy to address aviation safety. As a voluntary safety program, LOSA collects safety data during normal airline operations through peer observations in strict non-jeopardy conditions. Sponsored by the Federal Aviation Administration (FAA, an M&R LOSA project was launched in October 2008 to capitalize on the successes of flight deck LOSA and extend it to aviation maintenance and ramp operations. The project delivered an array of open source tools, including observation data collection forms, procedures, program manuals, scenario-based training, and databases. The M&R LOSA programs are expected to positively leverage peer pressure to enforce behavior change and allow subunits of an organization to build in some flexibility to address their key problems and assure the effectiveness of safety recommendations

  15. Application of (13)C ramp CPMAS NMR with phase-adjusted spinning sidebands (PASS) for the quantitative estimation of carbon functional groups in natural organic matter.

    Science.gov (United States)

    Ikeya, Kosuke; Watanabe, Akira

    2016-01-01

    The composition of carbon (C) functional groups in natural organic matter (NOM), such as dissolved organic matter, soil organic matter, and humic substances, is frequently estimated using solid-state (13)C NMR techniques. A problem associated with quantitative analysis using general cross polarization/magic angle spinning (CPMAS) spectra is the appearance of spinning side bands (SSBs) split from the original center peaks of sp (2) hybridized C species (i.e., aromatic and carbonyl C). Ramp CP/phase-adjusted side band suppressing (PASS) is a pulse sequence that integrates SSBs separately and quantitatively recovers them into their inherent center peaks. In the present study, the applicability of ramp CP/PASS to NOM analysis was compared with direct polarization (DPMAS), another quantitative method but one that requires a long operation time, and/or a ramp CP/total suppression side band (ramp CP/TOSS) technique, a popular but non-quantitative method for deleting SSBs. The test materials were six soil humic acid samples with various known degrees of aromaticity and two fulvic acids. There were no significant differences in the relative abundance of alkyl C, O-alkyl C, and aromatic C between the ramp CP/PASS and DPMAS methods, while the signal intensities corresponding to aromatic C in the ramp CP/TOSS spectra were consistently less than the values obtained in the ramp CP/PASS spectra. These results indicate that ramp CP/PASS can be used to accurately estimate the C composition of NOM samples.

  16. Verilog-A Device Models for Cryogenic Temperature Operation of Bulk Silicon CMOS Devices

    Science.gov (United States)

    Akturk, Akin; Potbhare, Siddharth; Goldsman, Neil; Holloway, Michael

    2012-01-01

    Verilog-A based cryogenic bulk CMOS (complementary metal oxide semiconductor) compact models are built for state-of-the-art silicon CMOS processes. These models accurately predict device operation at cryogenic temperatures down to 4 K. The models are compatible with commercial circuit simulators. The models extend the standard BSIM4 [Berkeley Short-channel IGFET (insulated-gate field-effect transistor ) Model] type compact models by re-parameterizing existing equations, as well as adding new equations that capture the physics of device operation at cryogenic temperatures. These models will allow circuit designers to create optimized, reliable, and robust circuits operating at cryogenic temperatures.

  17. Ramp compression of diamond to five terapascals.

    Science.gov (United States)

    Smith, R F; Eggert, J H; Jeanloz, R; Duffy, T S; Braun, D G; Patterson, J R; Rudd, R E; Biener, J; Lazicki, A E; Hamza, A V; Wang, J; Braun, T; Benedict, L X; Celliers, P M; Collins, G W

    2014-07-17

    The recent discovery of more than a thousand planets outside our Solar System, together with the significant push to achieve inertially confined fusion in the laboratory, has prompted a renewed interest in how dense matter behaves at millions to billions of atmospheres of pressure. The theoretical description of such electron-degenerate matter has matured since the early quantum statistical model of Thomas and Fermi, and now suggests that new complexities can emerge at pressures where core electrons (not only valence electrons) influence the structure and bonding of matter. Recent developments in shock-free dynamic (ramp) compression now allow laboratory access to this dense matter regime. Here we describe ramp-compression measurements for diamond, achieving 3.7-fold compression at a peak pressure of 5 terapascals (equivalent to 50 million atmospheres). These equation-of-state data can now be compared to first-principles density functional calculations and theories long used to describe matter present in the interiors of giant planets, in stars, and in inertial-confinement fusion experiments. Our data also provide new constraints on mass-radius relationships for carbon-rich planets.

  18. REDUCTION IN PROBABILITY OF TRAFFIC CONGESTION ON HIGH-CLASS ROAD USING RAMP ACCESS CONTROL

    Directory of Open Access Journals (Sweden)

    R. Yu. Lagerev

    2016-01-01

    Full Text Available Мerging traffic junctions on high-class roads are considered as bottlenecks in the network and quality of their operation determines a probability for formation of traffic congestions. Investigations on congestion situations in the merging zones of ramp and freeway traffic flows have demonstrated that queuing ramp traffic flow leads to formation of so called “turbulence” effect due to re-arrangement of transport facilities and reduction in their speed on main road direction. Having high queuing traffic flow on main road the “turbulence” component can result in formation of an impact blow in the main traffic flow. It has been proved that an impact of the ramp traffic flow on congestion probability is higher in comparison with main road traffic flow. The paper makes it possible to establish that some transport facilities moving along a high-way simul taneously occupy two lanes in the merging traffic zones and they reduce capacity of the used road section. It is necessary to take into account this specific feature and it is necessary to pay attention to it in the zones of “turbulence” effect formation. The paper presents main approaches, methodology, principles and stages required for access control of high-class roads which are directed on higher quality of their operation including improvement of road traffic safety. The paper proposes a methodоlogy that allows to evaluate and optimize ramp control in the context of a transport queue length minimization at adjoining ramps for the purposes of probability reduction in transport congestion.

  19. Probabilistic Wind Power Ramp Forecasting Based on a Scenario Generation Method: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Qin [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Florita, Anthony R [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Krishnan, Venkat K [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Hodge, Brian S [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-08-31

    Wind power ramps (WPRs) are particularly important in the management and dispatch of wind power, and they are currently drawing the attention of balancing authorities. With the aim to reduce the impact of WPRs for power system operations, this paper develops a probabilistic ramp forecasting method based on a large number of simulated scenarios. An ensemble machine learning technique is first adopted to forecast the basic wind power forecasting scenario and calculate the historical forecasting errors. A continuous Gaussian mixture model (GMM) is used to fit the probability distribution function (PDF) of forecasting errors. The cumulative distribution function (CDF) is analytically deduced. The inverse transform method based on Monte Carlo sampling and the CDF is used to generate a massive number of forecasting error scenarios. An optimized swinging door algorithm is adopted to extract all the WPRs from the complete set of wind power forecasting scenarios. The probabilistic forecasting results of ramp duration and start time are generated based on all scenarios. Numerical simulations on publicly available wind power data show that within a predefined tolerance level, the developed probabilistic wind power ramp forecasting method is able to predict WPRs with a high level of sharpness and accuracy.

  20. Ramp-rate limitation experiments in support of the TPX magnets

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, S.; Schultz, J.H.; Takayasu, Makoto; Michael, P.C. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Shen, S. [Lawrence Livermore National Lab., CA (United States); Vysotsky, V. [Kurchatov Inst., Moscow (Russian Federation); Warnes, W. [Oregon State Univ., Eugene, OR (United States)

    1995-12-31

    Fast magnetic field change is required for full-size tokamak reactors. The poloidal field magnets are usually ramped to full field at 1.2 T/s, and see pulsed fields of up to 20 T/s during plasma initiation. A new facility has been constructed at M.I.T. that simulates the expected operating conditions of the Tokamak Physics Experiment (TPX) magnets. New features in this facility include (1) a superconducting pulse coil that can superimpose high ramp-down rates, up to 25 T/s, (2 T in 80 msec) on a background field up to 5 T, (2) new power supplies that can supply high rates of dI/dt and dB/dt to the sample under test and the pulse coil, and (3) a forced-flow supercritical helium system that can simulate cooling conditions within the winding pack. The first sample tested in the facility is a 27-strand sub-cable, using 3.1:1 copper, noncopper ratio Nb{sub 3}Sn superconductor, typical of the strands to be used in ten of the poloidal field system magnets. This paper presents the first experimental results on the ramp rate limitation of the sub-size cable sample of TPX PF coil conductor. The transient stability at high ramp rate fields will be discussed.

  1. Integrated Variable Speed Limits Control and Ramp Metering for Bottleneck Regions on Freeway

    Directory of Open Access Journals (Sweden)

    Ming-hui Ma

    2015-01-01

    Full Text Available To enhance the efficiency of the existing freeway system and therefore to mitigate traffic congestion and related problems on the freeway mainline lane-drop bottleneck region, the advanced strategy for bottleneck control is essential. This paper proposes a method that integrates variable speed limits and ramp metering for freeway bottleneck region control to relieve the chaos in bottleneck region. To this end, based on the analyses of spatial-temporal patterns of traffic flow, a macroscopic traffic flow model is extended to describe the traffic flow operating characteristic by considering the impacts of variable speed limits in mainstream bottleneck region. In addition, to achieve the goal of balancing the priority of the vehicles on mainline and on-ramp, increasing capacity, and reducing travel delay on bottleneck region, an improved control model, as well as an advanced control strategy that integrates variable speed limits and ramp metering, is developed. The proposed method is tested in simulation for a real freeway infrastructure feed and calibrates real traffic variables. The results demonstrate that the proposed method can substantially improve the traffic flow efficiency of mainline and on-ramp and enhance the quality of traffic flow at the investigated freeway mainline bottleneck.

  2. A study of the heat treatment time, temperature and ramp rate on the transport current properties and Bi-2223 grain growth in (Bi,Pb)2223/Ag superconducting tapes

    CERN Document Server

    Young, E A

    2002-01-01

    The Bi-2223 phase formation in (Bi,Pb)2223/Ag tapes is known to be via a Pb rich liquid phase, the control of the wetting properties and the phase volume of liquid phase in the early hours of sintering can substantially improve the transport current of the final sintered tape. The phase volume of liquid phase, characterised by the formation of the Bi sub 2 (Sr sub 1 sub . sub 6 Ca sub 0 sub . sub 4)CuO sub 6 , (Bi-2201), phase, was observed to depend on the heat treatment temperature and atmosphere. The volume of secondary phases, (Cu sub 2 O, Cu-free phase, and Bi sub 2 (Sr sub 1 sub . sub 6 Ca sub 0 sub . sub 4)CuO sub 6), in the sintered Bi-2223 microstructure is shown to be sensitive to the sintering heating rate, and this is thought to be related to the wetting properties of the liquid phase. For an optimum transport critical current, (77K, self field), the heat treatment temperature and the heating rate are inter-dependent parameters, the heating rate only increasing the transport current of tapes heat ...

  3. Advanced Study of Unsteady Heat and Chemical Reaction with Ramped Wall and Slip Effect on a Viscous Fluid

    Science.gov (United States)

    Sohail, Ayesha; Maqbool, K.; Sher Akbar, Noreen; Younas, Muhammad

    2017-03-01

    This paper investigate the effect of slip boundary condition, thermal radiation, heat source, Dufour number, chemical reaction and viscous dissipation on heat and mass transfer of unsteady free convective MHD flow of a viscous fluid past through a vertical plate embedded in a porous media. Numerical results are obtained for solving the nonlinear governing momentum, energy and concentration equations with slip boundary condition, ramped wall temperature and ramped wall concentration on the surface of the vertical plate. The influence of emerging parameters on velocity, temperature and concentration fields are shown graphically.

  4. Comparison of photovoltaic cell temperatures in modules operating with exposed and enclosed back surfaces

    Science.gov (United States)

    Namkoong, D.; Simon, F. F.

    1981-01-01

    Four different photovoltaic module designs were tested to determine the cell temperature of each design. The cell temperatures were compared to those obtained on identical design, using the same nominal operating cell temperature (NOCT) concept. The results showed that the NOCT procedure does not apply to the enclosed configurations due to continuous transient conditions. The enclosed modules had higher cell temperatures than the open modules, and insulated modules higher than the uninsulated. The severest performance loss - when translated from cell temperatures - 17.5 % for one enclosed, insulated module as a compared to that module mounted openly.

  5. 40 CFR 1033.520 - Alternative ramped modal cycles.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Alternative ramped modal cycles. 1033.520 Section 1033.520 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF EMISSIONS FROM LOCOMOTIVES Test Procedures § 1033.520 Alternative ramped...

  6. Inter-Organisational Coordination in Ramp-Up Execution

    DEFF Research Database (Denmark)

    Christensen, Irene; Karlsson, Christer

    While fast product development with early prototyping and reduction of both cycle time and lead time are major concerns, there is little research on ramp up management. This paper examines the structural complexity of the ramp-up processes including the interactions with suppliers and analyses...

  7. How does the edge height of curb ramps obstruct bicycles?

    Science.gov (United States)

    Hayashi, Masahiro; Uetake, Teruo; Shimoda, Masahiro

    2012-12-01

    The aim of this study is to recommend revisions, based on empirical data, to the current curb ramp standards for keeping bicyclists safe. Four types of curb ramps were tested: (1) concrete with a 50 mm edge height, (2) concrete reinforced by a metal plate with a 50 mm edge height, (3) plastic with a 20 mm edge height, and (4) recycled rubber with a 10 mm edge height. Twenty subjects aged 20-60 years ascended the curbs on a bicycle under various conditions. The angles of approach were 15 degrees, 30 degrees, 45 degrees, 60 degrees, 75 degrees and 90 degrees. Experiments were executed under both wet and dry conditions. We found that when approaching from an angle of 45 degrees or more, all subjects could ascend all ramps under both conditions. From a 15 degrees approach under wet conditions, no subjects ascended the concrete ramps. Some could not ascend at a 15 degrees approach on the concrete ramps in dry conditions, and some could not ascend from a 30 degrees approach on the reinforced concrete ramp in wet conditions. Bicyclists riding on roadways cannot easily ascend a curb ramp with a 50 mm edge, even in dry conditions. We thus recommend that curb ramp edge heights be lower than 50 mm. Keywords: friction coefficient; approach angle

  8. High temperature brushless DC motor system and its operation mode control

    Institute of Scientific and Technical Information of China (English)

    邹继斌; 胡建辉; 徐永向

    2001-01-01

    The high temperature ( 175 ℃ ) operation of a motor spells out special requirements for control algorithms, materials and elements. The stability of motor characteristic is guaranteed by the digital control strategy. Constant velocity operation is achieved by phase-locked loop ( PLL), and constant power operation is achieved by a current-restricting circuit. A motor for constant speed and constant power operation has been built and the speed control system is tuned by MATLAB simulation. Experimental and simulation results for operation mode control of brushless DC motor are presented.

  9. Parametric Characterization of Reformate-operated PBI-based High Temperature PEM Fuel Cell Stack

    DEFF Research Database (Denmark)

    Sahlin, Simon Lennart

    2017-01-01

    This paper presents an experimental characterization of a HT-PEMFC short stack performed by means of impedance spectroscopy. Selected operating parameters; temperature, stoichiometry and reactant compositions were varied to investigate their effects on a reformate operated stack. Polarization...

  10. On the operation of silicon photomultipliers at temperatures of 1–4 kelvin

    Energy Technology Data Exchange (ETDEWEB)

    Achenbach, P., E-mail: patrick@kph.uni-mainz.de [Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz (Germany); Biroth, M., E-mail: biroth@kph.uni-mainz.de [Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz (Germany); Downie, E. [Physics Department, George Washington University, Washington DC (United States); Thomas, A. [Institut für Kernphysik, Johannes Gutenberg-Universität, Mainz (Germany)

    2016-07-11

    SiPM operation at cryogenic temperatures fails for many common devices. A particular type from Zecotek with deep channels in the silicon substrate instead of quenching resistors was tested at liquid helium temperature. Two similar types were thoroughly characterized from room temperature down to liquid nitrogen temperature by illuminating them with low light levels. At cryogenic temperatures the SiPMs show an unchanged rise-time and a fast recovery time, practically no after-pulses, and exhibit no increased cross-talk probability. Charge collection spectra were measured to extract the pixel gain and its variation, both comparable to room temperature at the same over-voltage. The quenching resistance was decreased at cryogenic temperature. It was found possible to use the characterized devices at temperatures of 1–4 K for the read-out of a target at the Mainz Microtron in Germany.

  11. Cell separator operation within temperature ranges to minimize effects on Chinese hamster ovary cell perfusion culture.

    Science.gov (United States)

    Drouin, Hans; Ritter, Joachim B; Gorenflo, Volker M; Bowen, Bruce D; Piret, James M

    2007-01-01

    A cell retention device that provides reliable high-separation efficiency with minimal negative effects on the cell culture is essential for robust perfusion culture processes. External separation devices generally expose cells to periodic variations in temperature, most commonly temperatures below 37 degrees C, while the cells are outside the bioreactor. To examine this phenomenon, aliquots of approximately 5% of a CHO cell culture were exposed to 60 s cyclic variations of temperature simulating an acoustic separator environment. It was found that, for average exposure temperatures between 31.5 and 38.5 degrees C, there were no significant impacts on the rates of growth, glucose consumption, or t-PA production, defining an acceptable range of operating temperatures. These results were subsequently confirmed in perfusion culture experiments for average exposure temperatures between 31.6 and 38.1 degrees C. A 2(5-1) central composite factorial design experiment was then performed to systematically evaluate the effects of different operating variables on the inlet and outlet temperatures of a 10L acoustic separator. The power input, ambient temperature, as well as the perfusion and recycle flow rates significantly influenced the temperature, while the cell concentration did not. An empirical model was developed that predicted the temperature changes between the inlet and the outlet of the acoustic separator within +/-0.5 degrees C. A series of perfusion experiments determined the ranges of the significant operational settings that maintained the acoustic separator inlet and outlet temperatures within the acceptable range. For example, these objectives were always met by using the manufacturer-recommended operational settings as long as the recirculation flow rate was maintained above 15 L day(-1) and the ambient temperature was near 22 degrees C.

  12. Assigning on-ramp flows to maximize highway capacity

    Science.gov (United States)

    Wang, Qiao-Ming; Jiang, Rui; Sun, Xiao-Yan; Wang, Bing-Hong

    2009-09-01

    In this paper, we study the capacity of a highway with two on-ramps by using a cellular automata traffic flow model. We investigate how to improve the system capacity by assigning traffic flow to the two ramps. The system phase diagram is presented and different regions are classified. It is shown that in region I, in which both ramps are in free flow and the main road upstream of the ramps is in congestion, assigning a higher proportion of the demand to the upstream on-ramp could improve the overall flow, which is consistent with previous studies. This is explained through studying the spatiotemporal patterns and analytical investigations. In contrast, optimal assignment has not been observed in other regions. We point out that our result is robust and model independent under certain conditions.

  13. High Temperature Electrolysis 4 kW Experiment Design, Operation, and Results

    Energy Technology Data Exchange (ETDEWEB)

    J.E. O' Brien; X. Zhang; K. DeWall; L. Moore-McAteer; G. Tao

    2012-09-01

    This report provides results of long-term stack testing completed in the new high-temperature steam electrolysis multi-kW test facility recently developed at INL. The report includes detailed descriptions of the piping layout, steam generation and delivery system, test fixture, heat recuperation system, hot zone, instrumentation, and operating conditions. This facility has provided a demonstration of high-temperature steam electrolysis operation at the 4 kW scale with advanced cell and stack technology. This successful large-scale demonstration of high-temperature steam electrolysis will help to advance the technology toward near-term commercialization.

  14. Power Generation by Zinc Antimonide Thin Film under Various Load Resistances at its Critical Operating Temperature

    DEFF Research Database (Denmark)

    Mir Hosseini, Seyed Mojtaba; Rezaniakolaei, Alireza; Rosendahl, Lasse Aistrup

    thin films operating under different load resistances at around its critical operating temperature, 400 ᵒC. The thermoelement is subjected to constant hot side temperature and to room temperature at the cold junction in order to measure the thin film TEG’s sample performance. The nominal loads equal......Thermoelectric generators (TEGs) use the Seebeck effect in semiconductors for direct conversion of heat to electrical energy. Zinc antimonide films were deposited on polished fused silica substrates by co-sputtering method in Aarhus University. This study focuses on stability of zinc antimonide...

  15. The Successful Operation of Hole-type Gaseous Detectors at Cryogenic Temperatures

    CERN Document Server

    Pereiale, L; Iacobaeus, C; Francke, T; Lund-Jensen, B; Pavlopoulos, P; Picchi, P; Pietropaolo, F; Tokanai, F

    2004-01-01

    We have demonstrated that hole-type gaseous detectors, GEMs and capillary plates, can operate up to 77 K. For example, a single capillary plate can operate at gains of above 10E3 in the entire temperature interval between 300 until 77 K. The same capillary plate combined with CsI photocathodes could operate perfectly well at gains (depending on gas mixtures) of 100-1000. Obtained results may open new fields of applications for capillary plates as detectors of UV light and charge particles at cryogenic temperatures: noble liquid TPCs, WIMP detectors or LXe scintillating calorimeters and cryogenic PETs.

  16. LHC Report: intensity ramp-up – familiar demons

    CERN Multimedia

    Mike Lamont for the LHC team

    2015-01-01

    The first 2015 scrubbing run ended on Friday, 3 July and successfully delivered a well-scrubbed machine ready for operation with a 50 ns beam. This opened the way for the first phase of the so-called beam intensity ramp-up. The last couple of weeks have seen the number of bunches increase from 3 to 476 per beam via periods of 50, 144 and 300 bunches per beam.   The graph plots the rate of LHC beam dumps due to single-event effects (SEE) versus beam luminosity. It is an indication of the importance of tackling this issue.   To verify the full and proper functioning of all systems, operators need at least 3 fills and 20 hours of stable beams without significant problems. After 20 hours, an extensive checklist is signed off by the system experts before the next step up in the number of bunches. The systems involved include magnet protection, radio-frequency, beam instrumentation, collimation, operations, feedback, beam dump and injection. Increasing the total beam intensity poses a numb...

  17. Ramp forecasting performance from improved short-term wind power forecasting over multiple spatial and temporal scales

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jie; Cui, Mingjian; Hodge, Bri-Mathias; Florita, Anthony; Freedman, Jeffrey

    2017-03-01

    The large variability and uncertainty in wind power generation present a concern to power system operators, especially given the increasing amounts of wind power being integrated into the electric power system. Large ramps, one of the biggest concerns, can significantly influence system economics and reliability. The Wind Forecast Improvement Project (WFIP) was to improve the accuracy of forecasts and to evaluate the economic benefits of these improvements to grid operators. This paper evaluates the ramp forecasting accuracy gained by improving the performance of short-term wind power forecasting. This study focuses on the WFIP southern study region, which encompasses most of the Electric Reliability Council of Texas (ERCOT) territory, to compare the experimental WFIP forecasts to the existing short-term wind power forecasts (used at ERCOT) at multiple spatial and temporal scales. The study employs four significant wind power ramping definitions according to the power change magnitude, direction, and duration. The optimized swinging door algorithm is adopted to extract ramp events from actual and forecasted wind power time series. The results show that the experimental WFIP forecasts improve the accuracy of the wind power ramp forecasting. This improvement can result in substantial costs savings and power system reliability enhancements.

  18. Analysis of Geo-Temperature Restoration Performance under Intermittent Operation of Borehole Heat Exchanger Fields

    Directory of Open Access Journals (Sweden)

    Chaofeng Li

    2015-12-01

    Full Text Available Intermittent operation can improve the coefficient of performance (COP of a ground source heat pump (GSHP system. In this paper, an analytical solution to analyze the geo-temperature restoration performance under intermittent operation of borehole heat exchanger (BHE fields is established. For this purpose, the moving finite line source model is combined with the g-function and the superposition principle. The model takes into account the heat transfer along the borehole, thermal interference between BHEs, and the influence of groundwater flow. The accuracy of the model is validated through comparison with an experiment carried out under intermittent operation. The model makes it possible to analyze the geo-temperature restoration performance and its influencing factors, such as BHE spacing, heat flow rate, operation mode, and groundwater flow. The main conclusions of this work are as follows. The heat transfer along the borehole should be considered when analyzing the geo-temperature restoration performance. When the BHE spacing increases, the soil temperature change decreases and the heat recovery improves. Therefore, adequate borehole separation distance is essential in the case of a multiple BHE system with unbalanced load. The presence of groundwater flow is associated with interference between the BHEs, which should not be ignored. In the case of long-term operation, the groundwater flow is beneficial to the geo-temperature recovery process, even for downstream BHEs. Finally, a greater groundwater flux leads to a better geo-temperature recovery.

  19. Operative environmental temperatures and basking behavior of the turtle Pseudemys scripta

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, K.M.; Spotila, J.R.; Standora, E.A.

    1983-01-01

    Operative environmental temperatures (T/sub e/, an index of the thermal environment) were measured for basking Pseudemys scripta in South Carolina. Operative environmental temperatures were good predictors of the basking behavior of P. scripta. Turtles in this study generally did not bask unless T/sub e/ was 28/sup 0/C (preferred body temperature) or higher. This demonstrated that basking was not a random behavior in respect to T/sub e/, and implicated thermoregulation as a major factor eliciting basking behavior. Operative environmental temperature was positively related to short-wave and total solar radiation as well as to air and substrate temperature. Substrate temperature was the best single predictor of T/sub e/. A multiple regression equation (T/sub e/ = 0.005R + 0.103T/sub a/ - 1.16 log V + 0.932T/sub s/ - 2.54, r/sup 2/ = .90, where R = total radiation in watts per square metre, T/sub a/ = air temperature in degrees Celsius, V = wind speed in metres per second, and T/sub s/ = substrate temperature in degrees Celsius) defines the relationship of T/sub e/ to microclimate variables. Movement of the sun through the day results in spatial variation in T/sub e/'s available to turtles and influences their location and basking behavior.

  20. Electrolytes for Use in High Energy Lithium-ion Batteries with Wide Operating Temperature Range

    Science.gov (United States)

    Smart, Marshall C.; Ratnakumar, B. V.; West, W. C.; Whitcanack, L. D.; Huang, C.; Soler, J.; Krause, F. C.

    2012-01-01

    Met programmatic milestones for program. Demonstrated improved performance with wide operating temperature electrolytes containing ester co-solvents (i.e., methyl butyrate) containing electrolyte additives in A123 prototype cells: Previously demonstrated excellent low temperature performance, including 11C rates at -30 C and the ability to perform well down to -60 C. Excellent cycle life at room temperature has been displayed, with over 5,000 cycles being demonstrated. Good high temperature cycle life performance has also been achieved. Demonstrated improved performance with methyl propionate-containing electrolytes in large capacity prototype cells: Demonstrated the wide operating temperature range capability in large cells (12 Ah), successfully scaling up technology from 0.25 Ah size cells. Demonstrated improved performance at low temperature and good cycle life at 40 C with methyl propionate-based electrolyte containing increasing FEC content and the use of LiBOB as an additive. Utilized three-electrode cells to investigate the electrochemical characteristics of high voltage systems coupled with wide operating temperature range electrolytes: From Tafel polarization measurements on each electrode, it is evident the NMC-based cathode displays poor lithium kinetics (being the limiting electrode). The MB-based formulations containing LiBOB delivered the best rate capability at low temperature, which is attributed to improved cathode kinetics. Whereas, the use of lithium oxalate as an additive lead to the highest reversible capacity and lower irreversible losses.

  1. Electrolytes for Use in High Energy Lithium-ion Batteries with Wide Operating Temperature Range

    Science.gov (United States)

    Smart, Marshall C.; Ratnakumar, B. V.; West, W. C.; Whitcanack, L. D.; Huang, C.; Soler, J.; Krause, F. C.

    2012-01-01

    Met programmatic milestones for program. Demonstrated improved performance with wide operating temperature electrolytes containing ester co-solvents (i.e., methyl butyrate) containing electrolyte additives in A123 prototype cells: Previously demonstrated excellent low temperature performance, including 11C rates at -30 C and the ability to perform well down to -60 C. Excellent cycle life at room temperature has been displayed, with over 5,000 cycles being demonstrated. Good high temperature cycle life performance has also been achieved. Demonstrated improved performance with methyl propionate-containing electrolytes in large capacity prototype cells: Demonstrated the wide operating temperature range capability in large cells (12 Ah), successfully scaling up technology from 0.25 Ah size cells. Demonstrated improved performance at low temperature and good cycle life at 40 C with methyl propionate-based electrolyte containing increasing FEC content and the use of LiBOB as an additive. Utilized three-electrode cells to investigate the electrochemical characteristics of high voltage systems coupled with wide operating temperature range electrolytes: From Tafel polarization measurements on each electrode, it is evident the NMC-based cathode displays poor lithium kinetics (being the limiting electrode). The MB-based formulations containing LiBOB delivered the best rate capability at low temperature, which is attributed to improved cathode kinetics. Whereas, the use of lithium oxalate as an additive lead to the highest reversible capacity and lower irreversible losses.

  2. Performance of Wide Operating Temperature Range Electrolytes in Quallion Prototype Li-Ion Cells

    Science.gov (United States)

    Smart, M. C.; Ratnakumar, B. V.; Tomcsi, M. R.; Nagata, M.; Visco, V.; Tsukamoto, H.

    2010-01-01

    For a number of applications, there is a continued interest in the development of rechargeable lithium-based batteries that can effectively operate over a wide temperature range (i.e., -40 to +70 deg C). These applications include powering future planetary rovers for NASA, enabling the next generation of automotive batteries for DOE, and supporting many DOD applications. Li-ion technology has been demonstrated to have good performance over a reasonably wide temperature range with many systems; however, there is still a desire to improve the low temperature rate capacity as well as the high temperature resilience. In the current study, we would like to present recent results obtained with prototype Li-Ion cells (manufactured by Quallion, LLC) which include various wide operating temperature range electrolytes developed by both JPL and Quallion. To demonstrate the viability of the technology, a number of performance tests were carried out, including: (a) discharge rate characterization over a wide temperature range (down to -60 deg C) using various rates (up to 20C rates), (b) discharge rate characterization at low temperatures with low temperature charging, (c) variable temperature cycling over a wide temperature range (-40 to +70 deg C), and (d) cycling at high temperature (50 deg C). As will be discussed, impressive rate capability was observed at low temperatures with many systems, as well as good resilience to high temperature cycling. To augment the performance testing on the prototype cells, a number of experimental three electrodes cells were fabricated (including Li reference electrodes) to allow the determination of the lithium kinetics of the respective electrodes and interfacial properties as a function of temperatures.

  3. Symmetrical dynamics of peak current-mode and valley current-mode controlled switching dc-dc converters with ramp compensation

    Science.gov (United States)

    Zhou, Guo-Hua; Xu, Jian-Ping; Bao, Bo-Cheng; Jin, Yan-Yan

    2010-06-01

    The discrete iterative map models of peak current-mode (PCM) and valley current-mode (VCM) controlled buck converters, boost converters, and buck-boost converters with ramp compensation are established and their dynamical behaviours are investigated by using the operation region, parameter space map, bifurcation diagram, and Lyapunov exponent spectrum. The research results indicate that ramp compensation extends the stable operation range of the PCM controlled switching dc-dc converter to D > 0.5 and that of the VCM controlled switching dc-dc converter to D converters with ramp compensation, VCM controlled switching dc-dc converters with ramp compensation exhibit interesting symmetrical dynamics. Experimental results are given to verify the analysis results in this paper.

  4. Effects of operation temperature on thermal expansion and main parameters of radial ball bearings

    Directory of Open Access Journals (Sweden)

    Mitrović Radivoje M.

    2015-01-01

    Full Text Available The research of influence of operation temperature on the thermal expansion and main parameters of radial ball bearings is presented in this paper. The main bearing parameters are identified in accordance with the increasing requests concerning stability and load capacity. A series of Finite Element Analyses is performed for quasi-static analysis of all identified bearing parameters during contact period in referent temperature. Then, the dependence of bearing material characteristics on the operation temperature is discussed. Few series of Finite Element Analyses are performed for a particular radial ball bearing type, with characteristics in accordance with manufacturer specifications, for several operation temperatures. These two problems analyses include consideration of relation between the initial radial clearance, thermal expansion strains and contact deformations of the parts of the bearing assembly. The results for radial ball bearing parameters are monitored during a ball contact period for different temperatures and the appropriate discussion and conclusions are given. The conclusions about the contribution of developed procedure in defining the optimum operation temperature range are shown. [Projekat Ministarstva nauke Republike Srbije, br. TR 35029 i br. OI 174001

  5. Operation of high- Tc SFQ devices at near liquid nitrogen temperature

    Science.gov (United States)

    Kim, Y. H.; Kang, J. H.; Lee, J. M.; Hahn, T. S.; Choi, S. S.; Park, S. J.

    1997-02-01

    As the operating temperature of the SFQ logic circuits gets higher by using high- Tc superconductors, the effect of noise on switching a Josephson junction to the voltage state becomes more important. In this paper, we report our work on high- Tc SFQ RS flip-flop which was made with YBCO thin film deposited on a SrTiO 3 bi-crystal. The circuit operated correctly at 71 K over the 200 computer-generated clock cycles without making errors, where a reset or a set operation was made over one clock cycle. Good agreement between the measured data and the calculation based on the thermal activation theory was obtained. The effective noise temperature used to fit the data was much higher than the physical temperature. This could be due to the instrument noise. Improvement in the measurement set-up might reduce the effective noise temperature. Also our measurement results indicate that the elevation of the operating temperature near the liquid nitrogen temperature may not affect the margin of the circuit.

  6. On the potential of solar cells to efficiently operate at high temperature

    Science.gov (United States)

    Zeitouny, Joya; Lalau, Noémie; Katz, Eugene A.; Dollet, Alain; Vossier, Alexis

    2017-09-01

    The development of high temperature CPV/thermal (CSP) hybrid systems appears to be a promising route to improve the overall solar to electricity conversion efficiency. Moreover, such systems would not only use the residual heat stemming from the unconverted fraction of the incident solar radiation in PV cells, but they would also provide the advantage of storing energy as heat. However, the performances of such hybrid systems depend strongly on the temperature of the thermal receivers which are only effective at high temperatures (typically above 250°C) while solar cells typically operate at temperatures close to ambient. An appropriate strategy is to make PV cells efficiently operate at temperature levels significantly exceeding the normal range of temperatures for which they are commonly designed. The degradation of electrical performance associated with high working temperature is less pronounced when the cell is submitted to high sunlight concentrations. An efficient photovoltaic conversion at temperature levels exceeding the ambient may however require significant modifications in the architecture of the cells. In this work, we assessed the feasibility of this strategy by studying the electrical properties as well as the overall efficiency of the PV/CSP system at different temperatures and sunlight illuminations.

  7. Study of Freeway Traffic Near an Off-Ramp

    OpenAIRE

    Cassidy, Michael J.; Anani, Shadi B.; Haigwood, John M.

    2000-01-01

    A bottleneck with a diminished capacity is shown to have arisen on a freeway segment whenever queues from the segment's off-ramped spilled over and occupied its mandatory exit lane. It is also shown that longer exit queues from the over-saturate off-ramp were accompanied by lower discharge rates for non-exiting vehicles. The explanation appears to be rubber-necking on the part of the non-exiting drivers. Whenever the of-ramp queues were prevented from spilling over to the exit lane (by changi...

  8. Inter-Organisational Coordination in Ramp-Up Execution

    DEFF Research Database (Denmark)

    Christensen, Irene; Karlsson, Christer

    While fast product development with early prototyping and reduction of both cycle time and lead time are major concerns, there is little research on ramp up management. This paper examines the structural complexity of the ramp-up processes including the interactions with suppliers and analyses...... the degree of fragmentation in the process planning and execution. Resource dependence theory (RDT) is used as central explanatory framework for inter-organisational interdependencies formation throughout the planning and execution of the ramp-up activities and milestones. This study aims at exploring inter...

  9. The effect of the operating temperatures and the solubility of paraffin on wax deposition

    Energy Technology Data Exchange (ETDEWEB)

    Han, Shanpeng [Beijing Key Laboratory for Urban Oil and Gas Distribution Technology, China University of Petroleum (China); Huang, Zhenyu; Fogler, H. Scott [Department of Chemical Engineering, University of Michigan (United States)], email: sfogler@umich.edu; Hoffmann, Rainer [Heroya Research Centre, Statoil ASA (Norway)

    2010-07-01

    Over time, wax deposits accumulate in subsea pipelines, generating major flow problems for the petroleum industry. Different flow loop experiments with various operating temperatures were conducted. The wax can be stimulated at different axial positions in the subsea pipelines depending on the temperature. In this paper, a series of experiments were carried out based on different inlet temperatures and a model was applied. The experimental results concluded that deposit thickness increases as the temperature at the inlet decreases. These results were contradictory of previous studies. To further examine this inconsistency in the model, theoretical analysis was conducted using the fundamentals of transport phenomena, both oil and crude oil were used. According to the model, the temperature gradient at the interface and change of wax solubility are the two leading causes which contribute to wax deposits. In conclusion, the paper finds that no generalization can be made about the inlet temperature without considering other factors.

  10. Broad negative thermal expansion operation-temperature window in antiperovskite manganese nitride with small crystallites

    Institute of Scientific and Technical Information of China (English)

    Jie Tan[1,2; Rongjin Huang[1; Wei Wang[1; Wen Li[1,2; YuqiangZhao[1,2; Shaopeng Li[1,2; Yemao Han[1,2; Chuanjun Huang[1; Laifeng Li[1

    2015-01-01

    Using spark plasma sintering (SPS), Mn3Cu0.6Ge0.4N crystallites have been fabricated with different crystallite sizes, and their magnetic properties and thermal behaviors were systemically investigated. With decreasing crystallite size, the magnetic transition becomes increasingly slow, accompanied by broadening of the negative thermal expansion (NTE) operation-temperature window. The NTE operation-temperature window for the 12-nm crystallite sample reaches at 140 K, which is about 75% larger than that of the 74-nm crystallite sample. The magnetic properties and NTE operation-temperature window can be tuned by varying the crystallite size. This discovery will promote an even wider range of practical applications in precision devices.

  11. Evaluation of Artificial Neural Network-Based Temperature Control for Optimum Operation of Building Envelopes

    Directory of Open Access Journals (Sweden)

    Jin Woo Moon

    2014-11-01

    Full Text Available This study aims at developing an indoor temperature control method that could provide comfortable thermal conditions by integrating heating system control and the opening conditions of building envelopes. Artificial neural network (ANN-based temperature control logic was developed for the control of heating systems and openings at the building envelopes in a predictive and adaptive manner. Numerical comparative performance tests for the ANN-based temperature control logic and conventional non-ANN-based counterpart were conducted for single skin enveloped and double skin enveloped buildings after the simulation program was validated by comparing the simulation and the field measurement results. Analysis results revealed that the ANN-based control logic improved the indoor temperature environment with an increased comfortable temperature period and decreased overshoot and undershoot of temperatures outside of the operating range. The proposed logic did not show significant superiority in energy efficiency over the conventional logic. The ANN-based temperature control logic was able to maintain the indoor temperature more comfortably and with more stability within the operating range due to the predictive and adaptive features of ANN models.

  12. Improved cycling behavior of ZEBRA battery operated at intermediate temperature of 175 °C

    Energy Technology Data Exchange (ETDEWEB)

    Li, Guosheng; Lu, Xiaochuan; Kim, Jin Y.; Lemmon, John P.; Sprenkle, Vincent L.

    2014-03-01

    Operation of the sodium-nickel chloride battery at temperatures below 200°C reduces cell degradation and improves cyclability. One of the main technical issues with operating this battery at intermediate temperatures such as 175°C is the poor wettability of molten sodium on β”-alumina solid electrolyte (BASE), which causes reduced active area and limits charging. In order to overcome the poor wettability of molten sodium on BASE at 175°C, a Pt grid was applied on the anode side of the BASE using a screen printing technique. Cells with their active area increased by metallized BASEs exhibited deeper charging and stable cycling behavior.

  13. Accelerating Science Driven System Design With RAMP

    Energy Technology Data Exchange (ETDEWEB)

    Wawrzynek, John [Univ. of California, Berkeley, CA (United States)

    2015-05-01

    Researchers from UC Berkeley, in collaboration with the Lawrence Berkeley National Lab, are engaged in developing an Infrastructure for Synthesis with Integrated Simulation (ISIS). The ISIS Project was a cooperative effort for “application-driven hardware design” that engages application scientists in the early parts of the hardware design process for future generation supercomputing systems. This project served to foster development of computing systems that are better tuned to the application requirements of demanding scientific applications and result in more cost-effective and efficient HPC system designs. In order to overcome long conventional design-cycle times, we leveraged reconfigurable devices to aid in the design of high-efficiency systems, including conventional multi- and many-core systems. The resulting system emulation/prototyping environment, in conjunction with the appropriate intermediate abstractions, provided both a convenient user programming experience and retained flexibility, and thus efficiency, of a reconfigurable platform. We initially targeted the Berkeley RAMP system (Research Accelerator for Multiple Processors) as that hardware emulation environment to facilitate and ultimately accelerate the iterative process of science-driven system design. Our goal was to develop and demonstrate a design methodology for domain-optimized computer system architectures. The tangible outcome is a methodology and tools for rapid prototyping and design-space exploration, leading to highly optimized and efficient HPC systems.

  14. LHC Report: Ramp-up complete

    CERN Document Server

    Mike Lamont for the LHC Team

    2012-01-01

    The intensity ramp-up outlined in the last Bulletin continued more or less as planned, with some steady running with 1092 bunches followed by the final step-up to 1380 – the maximum number of bunches for the year.   Monday, 16 April was spent performing luminosity calibration. Under carefully controlled conditions and a special beam configuration, the experiments' luminosity measurements were calibrated against a measurement of the accelerator’s absolute luminosity obtained with Van der Meer scans. These scans give the beam sizes at the interaction point which, together with an accurate measurement of the beam and bunch currents (and other more subtle considerations), allow a precise measurement of the absolute luminosity. With the Van der Meer scans out of the way, the final step-up in the number of bunches to 1380 was made. This has resulted in an average peak luminosity of around 5.6x1033 cm-2s-1 in the general-purpose detectors (ATLAS and CMS have yet to publish th...

  15. Temperature limits for LMFBR fuel cladding under upset and emergency operating conditions

    Energy Technology Data Exchange (ETDEWEB)

    Govindarajan, S.; Chetal, S.C. [Indira Gandhi Centre for Atomic Research, Kalpakkam Tamilnadu (India). Nuclear Systems Division

    1996-07-01

    LMFBR fuel pin cladding tube is subjected to high transient temperatures during incidents such as pump trip, pump to grid plate pipe rupture etc. It is required to know temperature limits under such transient operating conditions for components involved while analyzing such incidents. A methodology for deriving such limits for fuel clad tube is worked out in this paper by making use of the transient damage correlation proposed by W.F. Brizes et. al.

  16. Mirror thermal noise in laser interferometer gravitational wave detectors operating at room and cryogenic temperature

    CERN Document Server

    Franc, Janyce; Flaminio, Raffaele; Nawrodt, Ronny; Martin, Iain; Cunningham, Liam; Cumming, Alan; Rowan, Sheila; Hough, James

    2009-01-01

    Mirror thermal noise is and will remain one of the main limitations to the sensitivity of gravitational wave detectors based on laser interferometers. We report about projected mirror thermal noise due to losses in the mirror coatings and substrates. The evaluation includes all kind of thermal noises presently known. Several of the envisaged substrate and coating materials are considered. The results for mirrors operated at room temperature and at cryogenic temperature are reported.

  17. METHODS OF EVALUATION AND INDICATORS OF OPTIMAL TEMPERATURE OF INTERNAL COMBUSTION ENGINES AND VEHICLES IN OPERATION

    Directory of Open Access Journals (Sweden)

    V. Volkov

    2015-12-01

    Full Text Available The results of forming methods of determination and system, as a part of the computer-integrated technology of transport operation, estimation of indecies of the optimal temperature state of the ICE and the vehicle under operation conditions, which is provided with the help of analysis of possible schemes and processes of the complex system of combined heating, using the technology of heat accumulation are described.

  18. The Tool Life of Ball Nose end Mill Depending on the Different Types of Ramping

    Directory of Open Access Journals (Sweden)

    Vopát Tomáš

    2014-12-01

    Full Text Available The article deals with the cutting tool wear measurement process and tool life of ball nose end mill depending on upward ramping and downward ramping. The aim was to determine and compare the wear (tool life of ball nose end mill for different types of copy milling operations, as well as to specify particular steps of the measurement process. In addition, we examined and observed cutter contact areas of ball nose end mill with machined material. For tool life test, DMG DMU 85 monoBLOCK 5-axis CNC milling machine was used. In the experiment, cutting speed, feed rate, axial depth of cut and radial depth of cut were not changed. The cutting tool wear was measured on Zoller Genius 3s universal measuring machine. The results show different tool life of ball nose end mills depending on the copy milling strategy.

  19. Ramp length/grade prescriptions for wheelchair dependent individuals.

    Science.gov (United States)

    Canale, I; Felici, F; Marchetti, M; Ricci, B

    1991-09-01

    The aim of this work was to provide well defined criteria for ramp construction for wheelchair dependent individuals (WDI). Force capability was measured in a large sample (140) of WDI, who presented different levels of motor impairment. Levels of impairment were established on the basis of the answers given in a questionnaire regarding the degree of self sufficiency at home as well as outside the home and active participation in sports events. Taking into account those WDI who exhibited at least a minimal level of self-sufficiency, the following prescriptions are indicated. For a 1 metre ramp length, allowable maximal incline 15%; up to 3 metre ramp length, maximal incline 10%. The reliability of such prescriptions was confirmed by having a test ramp traversed by 43 WDI. These values are suggested as confidence limits when faced with public building accommodations. Special prescriptions could be adopted for selected populations of WDI.

  20. Optimization of the operation of a network of low temperature geothermal reservoirs

    OpenAIRE

    Hrannar Már Sigrúnarson 1975

    2013-01-01

    In 1930 the first low temperature geothermal reservoir was harvested in Reykjavik. In the decades that followed more reservoirs where harvested and in 1990 Nejsavellir power plant began operation and supplied hot water to Reykjavík. Today all hot water used in Reykjavík has it's source from low temperature geothermal reservoirs or power plants that heat up cold ground water with geothermal heat. Around Reykjavík there are four low temperature reservoirs and two power plants that produce water...

  1. 16nm planar process CMOS SRAM cell design: Analysis of Operating Voltage and Temperature Effect

    Directory of Open Access Journals (Sweden)

    Rohit Sharma

    2013-09-01

    Full Text Available Purpose: CMOS devices are scaling down to nano ranges resulting in increased process variations and short channel effects which not only affect the reliability of the device but also performance expectations. The SRAM design uses the smallest transistors possible and is also susceptible to reliability issues and process variations, making it an ideal benchmark circuit to compare the two technologies [1]. Low power static-random access memories (SRAM have become a critical component in modern VLSI systems. They occupy a large portion of area and accounts for a major component of power consumption in today’s VLSI circuits. In this paper we intend to analyse the performance of a traditional 6T SRAM cell of 16nm Complementary Metal Oxide Semiconductor (CMOS technology with change in Operating Voltage and Temperature. Aim: The aim of the paper is to study the effect of the SNM dependencies on the operating voltage and temperatureApproach: Conventional 6T SRAM are designed using predictive technology model developed by Arizona State University [2] of 16nm planar Low Power CMOS and variation of SNM with operating voltage and temperature are simulated and studied using hspice.Findings: Variations in the operating voltages and temperature strongly impact the stability of an SRAM cell at 16nm. Comparative study is done for predictive 16nm based conventional 6T SRAM cell by varying operating voltage and temperature. A methodology to select operating voltage is suggested which can be used in an early stage of a design cycle to optimise stability margins in nanometer regime

  2. Structural transformations and temperature state of rotating blades of E1893 alloy under operation

    Energy Technology Data Exchange (ETDEWEB)

    Pigrova, G.D.; Rybnikov, A.I.; Kryukov, I.I. [Polzunov Central Boiler and Turbine Institute, St. Petersburg (Russian Federation)

    1998-12-31

    The composition and quantity of different phase component of EI893 alloy after long term operation as base metal for rotating blades of gas turbines GT-6, GTN-9, GTK-10 and GT-100 types were studied. The obtained date were analysed with regard to the chemical composition of alloys and of initial condition of heat treatment. Data of metal phase analysis owned alter operation can provide the basis for evaluation of tempera field of rotating blades in the course of operation since structural condition of phase components and redistribution of alloying elements are being specified by temperature and in-service time. (orig.)

  3. Progress report on the design of a varying temperature irradiation experiment for operation in HFIR

    Energy Technology Data Exchange (ETDEWEB)

    Qualls, A.L. [Oak Ridge National Lab., TN (United States); Muroga, T.

    1997-04-01

    The purpose of this experiment is to determine effects of temperature variation during irradiation on microstructure and mechanical properties of potential fusion reactor structural materials. A varying temperature irradiation experiment is being performed under the framework of the Japan-USA Program of Irradiation Tests for fusion Research (JUPITER) to study the effects of temperature variation on the microstructure and mechanical properties of candidate fusion reactor structural materials. An irradiation capsule has been designed for operation in the High Flux Isotope Reactor at Oak Ridge National Laboratory that will allow four sets of metallurgical test specimens to be irradiated to exposure levels ranging from 5 to 10 dpa. Two sets of specimens will be irradiated at constant temperature of 500{degrees}C and 350{degrees}C. Matching specimen sets will be irradiated to similar exposure levels, with 10% of the exposure to occur at reduced temperatures of 300{degrees}C and 200{degrees}C.

  4. Ramp Metering by Limitation of Density and Queue Length

    Science.gov (United States)

    Kamel, Boumediene; Benasser, Amar; Jolly, Daniel

    2009-03-01

    As shown by many works and studies, the control of traffic flow remains the best and the efficient solution of the congestion problems. The ramp metering is a means to reduce congestion effects, it has shown his effectiveness to improve the flow and consequently to reduce the total time spent (TTS) by the vehicles in the network. In Kamel et al. [2008] the concept of flatness-based control was applied to regulate the flow at the mainline section of the road on the traffic flow model LWR. This work was preceded by Abouaïssa et al. [2006]. In this article we have proceeded the same way to set the flat output for a second order model METANET. Unfortunately we were unable to prove that the system is flat and therefore define density as flat output, but we manage to define the control laws in order to respect constraints on density and queue length at the on-ramp. The idea is to express the control variable (the outflow of the on-ramp) according to the output (density or queue length at the on-ramp), then inject it in the system. We use this control method in the ramp metering case. The first aim of the control is to keep the density in the segment where the on-ramp is connected below a density (called the target density YT) for which we have the lowest TTS, and the second aim is to keep the queue length at the on-ramp below a maximum value. In order to evaluate the controller's efficiency and applicability, a comparison is made with traditional ALINEA based controller. We illustrate this approach by comparing the cases 'no control' and 'ramp metering' for a simple network.

  5. Analytical delay models for RLC interconnects under ramp input

    Institute of Scientific and Technical Information of China (English)

    REN Yinglei; MAO Junfa; LI Xiaochun

    2007-01-01

    Analytical delay models for Resistance Inductance Capacitance (RLC)interconnects with ramp input are presented for difierent situations,which include overdamped,underdamped and critical response cases.The errors of delay estimation using the analytical models proposed in this paper are less bv 3%in comparison to the SPICE-computed delay.These models are meaningful for the delay analysis of actual circuits in which the input signal is ramp but not ideal step input.

  6. Extracting Strength from Ramp-Release Experiments on Z

    Science.gov (United States)

    Brown, Justin

    2013-06-01

    Releasing from a compressed state has long been recognized as a sensitive measure of a material's constitutive response. The initial elastic unloading provides insights which can be related to changes in shear stress or, in the context of classic plasticity, to the material's yield surface. Ramp compression and subsequent release experiments on Sandia's Z machine typically consist of a driving aluminum electrode pushing a sample material which is backed by a window. A particle velocity measurement of the sample/window interface provides a ramp-release profile. Under most circumstances, however, the impedance mismatch at this interface results in the measurement of a highly perturbed velocity, particularly at the late times of interest. Wave attenuation, the finite pressure range over which the material elastically unloads, and rate effects additionally complicate the interpretation of the experiment. In an effort to accurately analyze experiments of this type, each of these complications is addressed. The wave interactions are accounted for through the so-called transfer function methodology and involves a coupling of the experimental measurements with numerical simulations. Simulated window velocity measurements are combined with the corresponding in situ simulations to define a mapping describing the wave interactions due to the presence of the window. Applying this mapping to the experimentally measured velocity results in an in situ sample response which may then be used in a classic Lagrangian analysis from which the strength can be extracted via the self-consistent method. Corrections for attenuation, pressure averaging, and limitations of the analysis due to rate-effects are verified through the use of synthetic data. To date, results on the strength of aluminum to 1.2 MBar, beryllium to 1 MBar, and tantalum to over 2 MBar have been obtained through this methodology and will be presented. Sandia National Laboratories is a multi-program laboratory operated by

  7. PDR with a foot-mounted IMU and ramp detection.

    Science.gov (United States)

    Jiménez, Antonio R; Seco, Fernando; Zampella, Francisco; Prieto, José C; Guevara, Jorge

    2011-01-01

    The localization of persons in indoor environments is nowadays an open problem. There are partial solutions based on the deployment of a network of sensors (Local Positioning Systems or LPS). Other solutions only require the installation of an inertial sensor on the person's body (Pedestrian Dead-Reckoning or PDR). PDR solutions integrate the signals coming from an Inertial Measurement Unit (IMU), which usually contains 3 accelerometers and 3 gyroscopes. The main problem of PDR is the accumulation of positioning errors due to the drift caused by the noise in the sensors. This paper presents a PDR solution that incorporates a drift correction method based on detecting the access ramps usually found in buildings. The ramp correction method is implemented over a PDR framework that uses an Inertial Navigation algorithm (INS) and an IMU attached to the person's foot. Unlike other approaches that use external sensors to correct the drift error, we only use one IMU on the foot. To detect a ramp, the slope of the terrain on which the user is walking, and the change in height sensed when moving forward, are estimated from the IMU. After detection, the ramp is checked for association with one of the existing in a database. For each associated ramp, a position correction is fed into the Kalman Filter in order to refine the INS-PDR solution. Drift-free localization is achieved with positioning errors below 2 meters for 1,000-meter-long routes in a building with a few ramps.

  8. Dynamic control for nanostructures through slowly ramping parameters

    Science.gov (United States)

    Yoo, Jaeyun; Blick, Robert; Ahn, Kang-Hun

    2016-06-01

    We propose a nanostructure control method which uses slowly ramping parameters. We demonstrate the dynamics of this method in both a nonlinear classical system and a quantum system. When a quantum mechanical two-level atom (quantum dot) is irradiated by an electric field with a slowly increasing frequency, there exists a sudden transition from ground (excited) to excited (ground) state. This occurs when the ramping rate is smaller than the square of the Rabi frequency. The transition arises when its "instant frequency"—the time derivative of the driving field phase—matches the resonance frequency, satisfying the Fermi golden rule. We also find that the parameter ramping is an efficient control manner for classical nanomechanical shuttles. For ramping of driving amplitudes, the shuttle's mechanical oscillation is amplified and even survives when the ramping is stopped outside the original oscillation region. This strange oscillation is due to the entrance into a multistable dynamic region in phase space. For ramping of driving frequencies, an onset of oscillation arises when the instant frequency enters the oscillation region. Thus, regardless of being classical or quantum, the instant frequency is physically relevant. We discuss in which conditions the dynamic control is efficient.

  9. RESIDUAL OPERATIONAL RESOURCE ASSESSMENT OF HIGH TEMPERATURE ELEMENTS OF POWER ENGINEERING EQUIPMENT

    Directory of Open Access Journals (Sweden)

    S. E. Khoroshilov

    2014-01-01

    Full Text Available The paper proposes a specific assessment of heat resistant steel residual resource which  is  based  on  time determination of pore output on grain boundary with due account of an operational temperature, chemical composition and structure of the investigated steel.

  10. Room Temperature Operation of a Buried Heterostructure Photonic Crystal Quantum Cascade Laser

    CERN Document Server

    Peretti, R; Wolf, J M; Bonzon, C; Süess, M J; Lourdudoss, S; Metaferia, W; Beck, M; Faist, J

    2015-01-01

    We demonstrated room temperature operation of deep etched photonic crystal quantum cascade laser emitting around 8.5 micron. We fabricated buried heterostructure photonic crystals, resulting in single mode laser emission on a high order slow Bloch modes of the photonic crystal, between high symmetry points of the Brillouin.

  11. Monitoring operating temperature and supply voltage in achieving high system dependability

    NARCIS (Netherlands)

    Khan, M.A.; Kerkhoff, Hans G.

    2013-01-01

    System dependability being a set of number of attributes, of which the important reliability, heavily depends on operating temperature and supply voltage. Any change beyond the designed specifications may change the system performance and could result in system reliability and hence dependability

  12. Monitoring operating temperature and supply voltage in achieving high system dependability

    NARCIS (Netherlands)

    Khan, M.A.; Kerkhoff, Hans G.

    2013-01-01

    System dependability being a set of number of attributes, of which the important reliability, heavily depends on operating temperature and supply voltage. Any change beyond the designed specifications may change the system performance and could result in system reliability and hence dependability pr

  13. Monitoring operating temperature and supply voltage in achieving high system dependability

    NARCIS (Netherlands)

    Khan, Muhammad Aamir; Kerkhoff, Hans G.

    2013-01-01

    System dependability being a set of number of attributes, of which the important reliability, heavily depends on operating temperature and supply voltage. Any change beyond the designed specifications may change the system performance and could result in system reliability and hence dependability pr

  14. Ice formation in PEM fuel cells operated isothermally at sub-freezing temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Mukundan, Rangachary [Los Alamos National Laboratory; Luhan, Roger W [Los Alamos National Laboratory; Davey, John R [Los Alamos National Laboratory; Spendelow, Jacob S [Los Alamos National Laboratory; Borup, Rodney L [Los Alamos National Laboratory; Hussey, Daniel S [NIST; Jacobson, David L [NIST; Arif, Muhammad [NIST

    2009-01-01

    The effect of MEA and GDL structure and composition on the performance of single-PEM fuel cells operated isothermally at subfreezing temperatures is presented. The cell performance and durability are not only dependent on the MEA/GDL materials used but also on their interfaces. When a cell is operated isothermally at sub-freezing temperatures in constant current mode, the water formation due to the current density initially hydrates the membrane/ionomer and then forms ice in the catalyst layer/GDL. An increase in high frequency resistance was also observed in certain MEAs where there is a possibility of ice formation between the catalyst layer and GDL leading to a loss in contact area. The total water/ice holding capacity for any MEA was lower at lower temperatures and higher current densities. The durability of MEAs subjected to multiple isothermal starts was better for LANL prepared MEAs as compared to commercial MEAs, and cloth GDLs when compared to paper GDLs. The ice formation was monitored using high-resolution neutron radiography and was found to be concentrated near the cathode catalyst layer. However, there was significant ice formation in the GDLs especially at the higher temperature ({approx} -10 C) and lower current density (0.02 A/cm{sup 2}) operations. These results are consistent with the longer-term durability observations that show more severe degradation at the lower temperatures.

  15. Power-feedwater temperature operating domain for Sbwr applying Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar M, L. A.; Quezada G, S.; Espinosa M, E. G.; Vazquez R, A.; Varela H, J. R.; Cazares R, R. I.; Espinosa P, G., E-mail: sequega@gmail.com [Universidad Autonoma Metropolitana, Unidad Iztapalapa, San Rafael Atlixco No. 186, Col. Vicentina, 09340 Mexico D. F. (Mexico)

    2014-10-15

    In this work the analyses of the feedwater temperature effects on reactor power in a simplified boiling water reactor (Sbwr) applying a methodology based on Monte Carlo simulation is presented. The Monte Carlo methodology was applied systematically to establish operating domain, due that the Sbwr are not yet in operation, the analysis of the nuclear and thermal-hydraulic processes must rely on numerical modeling, with the purpose of developing or confirming the design basis and qualifying the existing or new computer codes to enable reliable analyses. The results show that the reactor power is inversely proportional to the temperature of the feedwater, reactor power changes at 8% when the feed water temperature changes in 8%. (Author)

  16. KINETIC MODELLING OF CONTINUOUS-MIX ANAEROBIC REACTORS OPERATING UNDER DIURNALLY CYCLIC TEMPERATURE ENVIRONMENT

    Directory of Open Access Journals (Sweden)

    E. A. Echiegu

    2014-01-01

    Full Text Available A two-culture dynamic model which incorporated the effects of diurnally cyclic temperature was developed and used to predict the dynamic response of anaerobic reactors operated on dairy manure under two diurnally cyclic temperature ranges of 20-40°C and 15-25°C which represent the summer and winter in Nigeria. The digesters were operated at various hydraulic retention times and solid concentrations and some useful kinetic parameters were determined. The model predicted biogas production, volatile solid reduction, methane yield and treatment efficiency with reasonable accuracy (R2 = 0.70 to 0.90. The model, however, under-predicted the cell mass concentration in the reactor probably because the Volatile Suspended Solid (VSS, which was used as the estimator of the actual cell mass concentration in the reactor, was not a good indicator of the active cell mass concentration in anaerobic reactors operating on dairy manure.

  17. Improved operation of graded-channel SOI nMOSFETs down to liquid helium temperature

    Science.gov (United States)

    Pavanello, Marcelo Antonio; de Souza, Michelly; Ribeiro, Thales Augusto; Martino, João Antonio; Flandre, Denis

    2016-11-01

    This paper presents the operation of Graded-Channel (GC) Silicon-On-Insulator (SOI) nMOSFETs at low temperatures down to liquid helium temperature in comparison to standard uniformly doped transistors. Devices from two different technologies have been measured and show that the mobility increase rate with temperature for GC SOI transistors is similar to uniformly doped devices for temperatures down to 90 K. However, at liquid helium temperature the rate of mobility increase is larger in GC SOI than in standard devices because of the different mobility scattering mechanisms. The analog properties of GC SOI devices have been investigated down to 4.16 K and show that because of its better transconductance and output conductance, an intrinsic voltage gain improvement with temperature is also obtained for devices in the whole studied temperature range. GC devices are also capable of reducing the impact ionization due to the high electric field in the drain region, increasing the drain breakdown voltage of fully-depleted SOI MOSFETs at any studied temperature and the kink voltage at 4.16 K.

  18. Orion Service Module Reaction Control System Plume Impingement Analysis Using PLIMP/RAMP2

    Science.gov (United States)

    Wang, Xiao-Yen; Lumpkin, Forrest E., III; Gati, Frank; Yuko, James R.; Motil, Brian J.

    2009-01-01

    The Orion Crew Exploration Vehicle Service Module Reaction Control System engine plume impingement was computed using the plume impingement program (PLIMP). PLIMP uses the plume solution from RAMP2, which is the refined version of the reacting and multiphase program (RAMP) code. The heating rate and pressure (force and moment) on surfaces or components of the Service Module were computed. The RAMP2 solution of the flow field inside the engine and the plume was compared with those computed using GASP, a computational fluid dynamics code, showing reasonable agreement. The computed heating rate and pressure using PLIMP were compared with the Reaction Control System plume model (RPM) solution and the plume impingement dynamics (PIDYN) solution. RPM uses the GASP-based plume solution, whereas PIDYN uses the SCARF plume solution. Three sets of the heating rate and pressure solutions agree well. Further thermal analysis on the avionic ring of the Service Module was performed using MSC Patran/Pthermal. The obtained temperature results showed that thermal protection is necessary because of significant heating from the plume.

  19. High-Operating Temperature HgCdTe: A Vision for the Near Future

    Science.gov (United States)

    Lee, D.; Carmody, M.; Piquette, E.; Dreiske, P.; Chen, A.; Yulius, A.; Edwall, D.; Bhargava, S.; Zandian, M.; Tennant, W. E.

    2016-09-01

    We review recent advances in the HgCdTe material quality and detector performance achieved at Teledyne using molecular beam epitaxy growth and the double-layer planar hetero-junction (DLPH) detector architecture. By using an un-doped, fully depleted absorber, Teledyne's DLPH architecture can be extended for use in high operating temperatures and other applications. We assess the potential achievable performance for long wavelength infrared (LWIR) hetero-junction p-lightly-doped n or p-intrinsic- n (p-i-n) detectors based on recently reported results for 10.7 μm cutoff 1 K × 1 K focal plane arrays (FPAs) tested at temperatures down to 30 K. Variable temperature dark current measurements show that any Shockley-Read-Hall currents in the depletion region of these devices have lifetimes that are reproducibly greater than 100 ms. Under the assumption of comparable lifetimes at higher temperatures, it is predicted that fully-depleted background radiation-limited performance can be expected for 10- μm cutoff detectors from room temperature to well below liquid nitrogen temperatures, with room-temperature dark current nearly 400 times lower than predicted by Rule 07. The hetero-junction p-i-n diode is shown to have numerous other significant potential advantages including minimal or no passivation requirements for pBn-like processing, low 1/ f noise, compatibility with small pixel pitch while maintaining high modulation transfer function, low crosstalk and good quantum efficiency. By appropriate design of the FPA dewar shielding, analysis shows that dark current can theoretically be further reduced below the thermal equilibrium radiative limit. Modeling shows that background radiation-limited LWIR HgCdTe operating with f/1 optics has the potential to operate within √2 of background-limited performance at 215 K. By reducing the background radiation by 2/3 using novel shielding methods, operation with a single-stage thermo-electric-cooler may be possible. If the

  20. Unified Geostatistical Modeling for Data Fusion and Spatial Heteroskedasticity with R Package ramps

    Directory of Open Access Journals (Sweden)

    Brian J. Smith

    2008-03-01

    Full Text Available This article illustrates usage of the ramps R package, which implements the reparameterized and marginalized posterior sampling (RAMPS algorithm for complex Bayesian geostatistical models. The RAMPS methodology allows joint modeling of areal and point-source data arising from the same underlying spatial process. A reparametrization of variance parameters facilitates slice sampling based on simplexes, which can be useful in general when multiple variances are present. Prediction at arbitrary points can be made, which is critical in applications where maps are needed. Our implementation takes advantage of sparse matrix operations in the Matrix package and can provide substantial savings in computing time for large datasets. A user-friendly interface, similar to the nlme mixed effects models package, enables users to analyze datasets with little programming effort. Support is provided for numerous spatial and spatiotemporal correlation structures, user-defined correlation structures, and non-spatial random effects. The package features are illustrated via a synthetic dataset of spatially correlated observation distributed across the state of Iowa, USA.

  1. End-pumped 1.5 microm monoblock laser for broad temperature operation.

    Science.gov (United States)

    Schilling, Bradley W; Chinn, Stephen R; Hays, A D; Goldberg, Lew; Trussell, C Ward

    2006-09-01

    We describe a next-generation monoblock laser capable of a greater than 10 mJ, 1.5 microm output at 10 pulses/s (pps) over broad ambient temperature extremes with no active temperature control. The transmitter design is based on a Nd:YAG laser with a Cr4+ passive Q switch and intracavity potassium titanyl phosphate optical parametric oscillator. To achieve the repetition rate and efficiency goals of this effort, but still have wide temperature capability, the Nd:YAG slab is end pumped with a 12-bar stack of 100 W (each) diode bars. Different techniques for focusing the pump radiation into the 4.25 mmx4.25 mm end of the slab are compared, including a lensed design, a reflective concentrator, and a lens duct. A wide temperature operation (-20 degrees C to 50 degrees C) for each end-pumped configuration is demonstrated.

  2. Study of the operation temperature in the spin-exchange relaxation free magnetometer.

    Science.gov (United States)

    Fang, Jiancheng; Li, Rujie; Duan, Lihong; Chen, Yao; Quan, Wei

    2015-07-01

    We study the influence of the cell temperature on the sensitivity of the spin-exchange relaxation free (SERF) magnetometer and analyze the possibility of operating at a low temperature. Utilizing a 25 × 25 × 25 mm(3) Cs vapor cell with a heating temperature of 85 °C, which is almost half of the value of potassium, we obtain a linewidth of 1.37 Hz and achieve a magnetic field sensitivity of 55 fT/Hz(1/2) in a single channel. Theoretical analysis shows that fundamental sensitivity limits of this device with an active volume of 1 cm(3) could approach 1 fT/Hz(1/2). Taking advantage of the higher saturated vapor pressure, SERF magnetometer based on Cs opens up the possibility for low cost and portable sensors and is particularly appropriate for lower temperature applications.

  3. High performance shape memory effect in nitinol wire for actuators with increased operating temperature range

    Science.gov (United States)

    Casati, Riccardo; Biffi, Carlo Alberto; Vedani, Maurizio; Tuissi, Ausonio

    2014-07-01

    In this research, the high performance shape memory effect (HP-SME) is experimented on a shape memory NiTi wire, with austenite finish temperature higher than room temperature. The HP-SME consists in the thermal cycling of stress induced martensite and it allows achieving mechanical work higher than that produced by conventional shape memory actuators based on the heating/cooling of detwinned martensite. The Nitinol wire was able to recover about 5.5% of deformation under a stress of 600 MPa and to withstand about 5000 cycles before failure. HP-SME path increased the operating temperature of the shape memory actuator wire. Functioning temperatures higher than 100°C was reached.

  4. Validity of thermal ramping assays used to assess thermal tolerance in arthropods.

    Science.gov (United States)

    Overgaard, Johannes; Kristensen, Torsten Nygaard; Sørensen, Jesper Givskov

    2012-01-01

    Proper assessment of environmental resistance of animals is critical for the ability of researchers to understand how variation in environmental conditions influence population and species abundance. This is also the case for studies of upper thermal limits in insects, where researchers studying animals under laboratory conditions must select appropriate methodology on which conclusions can be drawn. Ideally these methods should precisely estimate the trait of interest and also be biological meaningful. In an attempt to develop such tests it has been proposed that thermal ramping assays are useful assays for small insects because they incorporate an ecologically relevant gradual temperature change. However, recent model-based papers have suggested that estimates of thermal resistance may be strongly confounded by simultaneous starvation and dehydration stress. In the present study we empirically test these model predictions using two sets of independent experiments. We clearly demonstrate that results from ramping assays of small insects (Drosophila melanogaster) are not compromised by starvation- or dehydration-stress. Firstly we show that the mild disturbance of water and energy balance of D. melanogaster experienced during the ramping tests does not confound heat tolerance estimates. Secondly we show that flies pre-exposed to starvation and dehydration have "normal" heat tolerance and that resistance to heat stress is independent of the energetic and water status of the flies. On the basis of our results we discuss the assumptions used in recent model papers and present arguments as to why the ramping assay is both a valid and ecologically relevant way to measure thermal resistance in insects.

  5. Validity of thermal ramping assays used to assess thermal tolerance in arthropods.

    Directory of Open Access Journals (Sweden)

    Johannes Overgaard

    Full Text Available Proper assessment of environmental resistance of animals is critical for the ability of researchers to understand how variation in environmental conditions influence population and species abundance. This is also the case for studies of upper thermal limits in insects, where researchers studying animals under laboratory conditions must select appropriate methodology on which conclusions can be drawn. Ideally these methods should precisely estimate the trait of interest and also be biological meaningful. In an attempt to develop such tests it has been proposed that thermal ramping assays are useful assays for small insects because they incorporate an ecologically relevant gradual temperature change. However, recent model-based papers have suggested that estimates of thermal resistance may be strongly confounded by simultaneous starvation and dehydration stress. In the present study we empirically test these model predictions using two sets of independent experiments. We clearly demonstrate that results from ramping assays of small insects (Drosophila melanogaster are not compromised by starvation- or dehydration-stress. Firstly we show that the mild disturbance of water and energy balance of D. melanogaster experienced during the ramping tests does not confound heat tolerance estimates. Secondly we show that flies pre-exposed to starvation and dehydration have "normal" heat tolerance and that resistance to heat stress is independent of the energetic and water status of the flies. On the basis of our results we discuss the assumptions used in recent model papers and present arguments as to why the ramping assay is both a valid and ecologically relevant way to measure thermal resistance in insects.

  6. Flow and containment characteristics of an air-curtain fume hood operated at high temperatures.

    Science.gov (United States)

    Chen, Jia-Kun; Huang, Rong Fung; Hsin, Pei-Yi; Hsu, Ching Min; Chen, Chun-Wann

    2012-01-01

    The flow and leakage characteristics of the air-curtain fume hood under high temperature operation (between 100°C and 250°C) were studied. Laser-assisted flow visualization technique was used to reveal the hot plume movements in the cabinet and the critical conditions for the hood-top leakage. The sulfur hexafluoride tracer-gas concentration test method was employed to examine the containment spillages from the sash opening and the hood top. It was found that the primary parameters dominating the behavior of the flow field and hood performance are the sash height and the suction velocity as an air-curtain hood is operated at high temperatures. At large sash height and low suction velocity, the air curtain broke down and accompanied with three-dimensional flow in the cabinet. Since the suction velocity was low and the sash opening was large, the makeup air drawn down from the hood top became insufficient to counter act the rising hot plume. Under this situation, containment leakage from the sash opening and the hood top was observed. At small sash opening and high suction velocity, the air curtain presented robust characteristics and the makeup air flow from the hood top was sufficiently large. Therefore the containment leakages from the sash opening and the hood top were not observed. According to the results of experiments, quantitative operation sash height and suction velocity corresponding to the operation temperatures were suggested.

  7. S∧4 Reactor: Operating Lifetime and Estimates of Temperature and Burnup Reactivity Coefficients

    Science.gov (United States)

    King, Jeffrey C.; El-Genk, Mohamed S.

    2006-01-01

    The S∧4 reactor has a sectored, Mo-14%Re solid core for avoidance of single point failures in reactor cooling and Closed Brayton Cycle (CBC) energy conversion. The reactor is loaded with UN fuel, cooled with a He-Xe gas mixture at ~1200 K and operates at steady thermal power of 550 kW. Following a launch abort accident, the axial and radial BeO reflectors easily disassemble upon impact so that the bare reactor is subcriticial when submerged in wet sand or seawater and the core voids are filled with seawater. Spectral Shift Absorber (SSA) additives have been shown to increase the UN fuel enrichment and significantly reduce the total mass of the reactor. This paper investigates the effects of SSA additions on the temperature and burnup reactivity coefficients and the operational lifetime of the S∧4 reactor. SSAs slightly decrease the temperature reactivity feedback coefficient, but significantly increase the operating lifetime by decreasing the burnup reactivity coefficient. With no SSAs, fuel enrichment is only 58.5 wt% and the estimated operating lifetime is the shortest (7.6 years) with the highest temperature and burnup reactivity feedback coefficients (-0.2709 ¢/K and -1.3470 $/atom%). With europium-151 and gadolinium-155 additions, the enrichment (91.5 and 94 wt%) and operating lifetime (9.9 and 9.8 years) of the S∧4 reactor are the highest while the temperature and burnup reactivity coefficients (-0.2382 and -0.2447 ¢/K -0.9073 and 0.8502 $/atom%) are the lowest.

  8. Assessment of SOI AND Gate, Type CHT-7408, for Operation in Extreme Temperature Environments

    Science.gov (United States)

    Patterson, Richard; Hammoud, Ahmad; Dones, Keishla Rivera

    2009-01-01

    Electronic parts based on silicon-on-insulator (SOI) technology are finding widespread applications due to their ability to operate in harsh environments and the benefits they offer as compared to their silicon counterparts. Due to their construction, they are tailored for high temperature operation and show good tolerance to radiation events. In addition, their inherent design lessens the formation of parasitic junctions, thereby reducing leakage currents, decreasing power consumption, and enhancing speed. These devices are typically rated in temperature capability from -55 C to about +225 C, and their characteristics over this temperature range are documented in data sheets. Since electronics in some of NASA space exploration missions are required to operate under extreme temperature conditions, both cold and hot, their characteristic behavior within the full temperature spectrum must be determined to establish suitability for use in space applications. The effects of extreme temperature exposure on the performance of a new commercial-off-the-shelf (COTS) SOI AND gate device were evaluated in this work. The high temperature, quad 2-inputs AND gate device, which was recently introduced by CISSOID, is fabricated using a CMOS SOI process. Some of the specifications of the CHT-7408 chip are listed in a table. By supplying a constant DC voltage to one gate input and a 10 kHz square wave into the other associated gate input, the chip was evaluated in terms of output response, output rise (t(sub r)) and fall times (tf), and propagation delays (using a 50% level between input and output during low to high (tPLH) and high to low (tPHL) transitions). The supply current of the gate circuit was also obtained. These parameters were recorded at various test temperatures between -195 C and +250 C using a Sun Systems environmental chamber programmed at a temperature rate of change of 10 C/min. In addition, the effects of thermal cycling on this chip were determined by exposing

  9. Solar thermal collectors in polymeric materials: A novel approach towards higher operating temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Mendes, Joao Farinha; Horta, Pedro; Carvalho, Maria Joao [INETI - Inst. Nacional de Engenharia Tecnologia e Inovacao, IP, Lisboa (Portugal); Silva, Paulo [PLASDAN - Maquinas para Plasticos, Marinha Grande (Portugal)

    2008-07-01

    The increasing demand for low temperature solar thermal collectors, especially for hot water production purposes in dwellings, swimming pools, hotels or industry, has lead to the possibility of high scale production, with leading manufacturers presenting yearly productions of hundreds of thousands of square meters. In such conditions, the use of polymeric materials in the manufacturing of solar collectors acquires particular interest, opening a full scope of opportunities for lower production costs, by means of cheaper materials or simpler manufacturing operations. Yet, the use of low cost materials limits the maximum operating temperatures estimated for the collectors (stagnation) to values around 120 C, easily attainable by any simple glazed solar collector. Higher performances, leading to higher stagnation temperatures as those observed for regular metal-based solar thermal collectors, would require high temperature polymers, at a much higher cost. The present paper addresses the manufacturing of a high performance solar thermal collector based in polymeric materials and includes a base thermal study, highlighting the different possibilities to be followed in the production of a polymeric collector, as well as a description of different temperature control strategies. (orig.)

  10. Operation of a Giant Magnetoresistive (GMR) Digital Isolator, Type IL510, Under Extreme Temperatures

    Science.gov (United States)

    Patterson, Richard; Hammoud, Ahmad; Panko, Scott

    2010-01-01

    A relatively new type of signal isolation based on Giant Magnetoresistive (GMR) technology was investigated for potential use in harsh temperature environments. Operational characteristics of the 2Mbps single channel, IL510-Series commercial-off-the-shelf (COTS) digital isolator chip was obtained under extreme temperature exposure and thermal cycling in the range of -190 C to +120 C. The isolator was evaluated in terms of its output signal delivery and stability, output rise (t(sub r)) and fall times (t(sub f)), and propagation delays at 50% level between input and output during low to high (t(sub PLH)) and high to low (t(sub PHL)) transitions. The device performed very well throughout the entire test temperature range as no significant changes occurred either in its function or in its output signal timing characteristics. The limited thermal cycling, which comprised of 12 cycles between -190 C and +120 C, also had no influence on its performance. In addition, the device packaging underwent no structural damage due to the extreme temperature exposure. These preliminary results indicate that this semiconductor chip has the potential for use in a temperature range that extends beyond its specified regime. Additional and more comprehensive testing, however, is required to establish its operation and reliability and to determine its suitability for long-term use in space exploration missions.

  11. Comparison of rechargeable versus battery-operated insulin pumps: temperature fluctuations

    Directory of Open Access Journals (Sweden)

    Vereshchetin P

    2016-10-01

    Full Text Available Paul Vereshchetin, Thomas W McCann Jr, Navdeep Ojha, Ramakrishna Venugopalan, Brian L Levy Johnson & Johnson Diabetes Care Companies, Chesterbrook, PA, USA Abstract: The role of continuous subcutaneous insulin infusion (insulin pumps has become increasingly important in diabetes management, and many different types of these systems are currently available. This exploratory study focused on the reported heating issues that lithium-ion battery-powered pumps may have during charging compared with battery-operated pumps. It was found that pump temperature increased by 6.4°C during a long charging cycle of a lithium-ion battery-operated pump under ambient temperatures. In an environmental-chamber kept at 35°C, the pump temperature increased by 4.4°C, which indicates that the pump temperature was above that of the recommended safety limit for insulin storage of 37°C. When designing new pumps, and when using currently available rechargeable pumps in warmer climates, the implications of these temperature increases should be taken into consideration. Future studies should also further examine insulin quality after charging. Keywords: insulin pumps, diabetes mellitus, safety, heating

  12. High-temperature operation of broadband bidirectional terahertz quantum-cascade lasers

    Science.gov (United States)

    Khanal, Sudeep; Gao, Liang; Zhao, Le; Reno, John L.; Kumar, Sushil

    2016-09-01

    Terahertz quantum cascade lasers (QCLs) with a broadband gain medium could play an important role for sensing and spectroscopy since then distributed-feedback schemes could be utilized to produce laser arrays on a single semiconductor chip with wide spectral coverage. QCLs can be designed to emit at two different frequencies when biased with opposing electrical polarities. Here, terahertz QCLs with bidirectional operation are developed to achieve broadband lasing from the same semiconductor chip. A three-well design scheme with shallow-well GaAs/Al0.10Ga0.90As superlattices is developed to achieve high-temperature operation for bidirectional QCLs. It is shown that shallow-well heterostructures lead to optimal quantum-transport in the superlattice for bidirectional operation compared to the prevalent GaAs/Al0.15Ga0.85As material system. Broadband lasing in the frequency range of 3.1-3.7 THz is demonstrated for one QCL design, which achieves maximum operating temperatures of 147 K and 128 K respectively in opposing polarities. Dual-color lasing with large frequency separation is demonstrated for a second QCL, that emits at ~3.7 THz and operates up to 121 K in one polarity, and at ~2.7 THz up to 105 K in the opposing polarity. These are the highest operating temperatures achieved for broadband terahertz QCLs at the respective emission frequencies, and could lead to commercial development of broadband terahertz laser arrays.

  13. Operational and theoretical temperature considerations in a Penning surface plasma source

    Energy Technology Data Exchange (ETDEWEB)

    Faircloth, D. C., E-mail: dan.faircloth@stfc.ac.uk; Lawrie, S. R. [ISIS Neutron and Muon Facility, STFC Rutherford Appleton Laboratory, Harwell Oxford, OX11 0QX (United Kingdom); Pereira Da Costa, H. [CERN, Geneva (Switzerland); Dudnikov, V. [Muons Inc. United States of America (United States)

    2015-04-08

    A fully detailed 3D thermal model of the ISIS Penning surface plasma source is developed in ANSYS. The proportion of discharge power applied to the anode and cathode is varied until the simulation matches the operational temperature observations. The range of possible thermal contact resistances are modelled, which gives an estimation that between 67% and 85% of the discharge power goes to the cathode. Transient models show the electrode surface temperature rise during the discharge pulse for a range of duty cycles. The implications of these measurements are discussed and a mechanism for governing cesium coverage proposed. The requirements for the design of a high current long pulse source are stated.

  14. Modeling Temperature Development of Li-Ion Battery Packs in Hybrid Refuse Truck Operating at Different Ambient Conditions

    DEFF Research Database (Denmark)

    Coman, Paul Tiberiu; Veje, Christian

    2014-01-01

    This paper presents a dynamic model for simulating the heat dissipation and the impact of Phase Change Materials (PCMs) on the peak temperature in Lithium-ion batteries during discharging operation of a hybrid truck under different ambient temperatures.......This paper presents a dynamic model for simulating the heat dissipation and the impact of Phase Change Materials (PCMs) on the peak temperature in Lithium-ion batteries during discharging operation of a hybrid truck under different ambient temperatures....

  15. Modeling Temperature Development of Li-Ion Battery Packs in Hybrid Refuse Truck Operating at Different Ambient Conditions

    DEFF Research Database (Denmark)

    Coman, Paul Tiberiu; Veje, Christian

    2014-01-01

    This paper presents a dynamic model for simulating the heat dissipation and the impact of Phase Change Materials (PCMs) on the peak temperature in Lithium-ion batteries during discharging operation of a hybrid truck under different ambient temperatures.......This paper presents a dynamic model for simulating the heat dissipation and the impact of Phase Change Materials (PCMs) on the peak temperature in Lithium-ion batteries during discharging operation of a hybrid truck under different ambient temperatures....

  16. Room-temperature operation of mid-infrared surface-plasmon quantum cascade lasers

    Science.gov (United States)

    Bahriz, M.; Moreau, V.; Palomo, J.; Krysa, A. B.; Austin, D.; Cockburn, J. W.; Roberts, J. S.; Wilson, L. R.; Julien, F.; Colombelli, R.

    2007-04-01

    We report the pulsed, room-temperature operation of an InGaAs/AllnAs quantum cascade laser at an operating wavelength of ≈ 7.5 μm in which the optical mode is a surface-plasmon polariton excitation. The use of a silver-based electrical contact with reduced optical losses at the laser emission wavelength allows for a reduction of the laser threshold current by a factor of two relative to samples with a gold-based contact layer.

  17. High Temperature Operation of 5.5μm Strain-Compensated Quantum Cascaded Lasers

    Institute of Scientific and Technical Information of China (English)

    LU Xiu-Zhen; LIU Feng-Qi; LIU Jun-Qi; JIN Peng; WANG Zhan-Guo

    2005-01-01

    @@ We develop 5.5-μm Inx Ga1-xAs/InyAl1-yAs strain-compensated quantum cascade lasers with InP and InGaAs cladding layers by using solid-source molecular-beam epitaxy. Pulse operation has been achieved up to 323K (50℃) for uncoated 20-μm-wide and 2-mm-long devices. These devices display an output power of 36mW with a duty cycle of 1% at room temperature. In continuous wave operation a record peak optical power of 10mW per facet has been measured at 83 K.

  18. A simple microfluidic Coriolis effect flowmeter for operation at high pressure and high temperature

    Science.gov (United States)

    Harrison, Christopher; Jundt, Jacques

    2016-08-01

    We describe a microfluidic Coriolis effect flowmeter that is simple to assemble, operates at elevated temperature and pressure, and can be operated with a lock-in amplifier. The sensor has a flow rate sensitivity greater than 2° of phase shift per 1 g/min of mass flow and is benchmarked with flow rates ranging from 0.05 to 2.0 g/min. The internal volume is 15 μl and uses off-the-shelf optical components to measure the tube motion. We demonstrate that fluid density can be calculated from the frequency of the resonating element with proper calibration.

  19. Off-ramps and on-ramps: keeping talented women on the road to success.

    Science.gov (United States)

    Hewlett, Sylvia Ann; Luce, Carolyn Buck

    2005-03-01

    Most professional women step off the career fast track at some point. With children to raise, elderly parents to care for, and other pulls on their time, these women are confronted with one off-ramp after another. When they feel pushed at the same time by long hours and unsatisfying work, the decision to leave becomes even easier. But woe to the woman who intends for that exit to be temporary. The on-ramps for professional women to get back on track are few and far between, the authors confirm. Their new survey research reveals for the first time the extent of the problem--what percentage of highly qualified women leave work and for how long, what obstacles they face coming back, and what price they pay for their time-outs. And what are the implications for corporate America? One thing at least seems clear: As market and economic factors align in ways guaranteed to make talent constraints and skill shortages huge issues again, employers must learn to reverse this brain drain. Like it or not, large numbers of highly qualified, committed women need to take time out of the workplace. The trick is to help them maintain connections that will allow them to reenter the workforce without being marginalized for the rest of their lives. Strategies for building such connections include creating reduced-hour jobs, providing flexibility in the workday and in the arc of a career, removing the stigma of taking time off, refusing to burn bridges, offering outlets for altruism, and nurturing women's ambition.

  20. Assessment of the Operating Temperature of Crystalline PV Modules Based on Real Use Conditions

    Directory of Open Access Journals (Sweden)

    Giuseppina Ciulla

    2014-01-01

    Full Text Available Determining the operating temperature Tc of photovoltaic panels PV is important in evaluating the actual performance of these systems. In the literature, different correlations exist, in either explicit or implicit forms, which often do not account for the electrical behaviour of panels; in this way, estimating Tc is based only on the passive behaviour of the PV. In this paper, the authors propose a new implicit correlation that takes into account the standard weather variables and the electricity production regimes of a PV panel in terms of the proximity to the maximum power points. To validate its reliability, the new correlation was tested on two different PV panels (Sanyo and Kyocera panels and the results were compared with values obtained from other common correlations already available in the literature. The data show that the quality of the new correlation drastically improves the estimation of the photovoltaic operating temperature.

  1. High-density magnetoresistive random access memory operating at ultralow voltage at room temperature.

    Science.gov (United States)

    Hu, Jia-Mian; Li, Zheng; Chen, Long-Qing; Nan, Ce-Wen

    2011-11-22

    The main bottlenecks limiting the practical applications of current magnetoresistive random access memory (MRAM) technology are its low storage density and high writing energy consumption. Although a number of proposals have been reported for voltage-controlled memory device in recent years, none of them simultaneously satisfy the important device attributes: high storage capacity, low power consumption and room temperature operation. Here we present, using phase-field simulations, a simple and new pathway towards high-performance MRAMs that display significant improvements over existing MRAM technologies or proposed concepts. The proposed nanoscale MRAM device simultaneously exhibits ultrahigh storage capacity of up to 88 Gb inch(-2), ultralow power dissipation as low as 0.16 fJ per bit and room temperature high-speed operation below 10 ns.

  2. The Integrity of ACSR Full Tension Single-Stage Splice Connector at Higher Operation Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [ORNL; Lara-Curzio, Edgar [ORNL; King Jr, Thomas J [ORNL

    2008-10-01

    Due to increases in power demand and limited investment in new infrastructure, existing overhead power transmission lines often need to operate at temperatures higher than those used for the original design criteria. This has led to the accelerated aging and degradation of splice connectors. It is manifested by the formation of hot-spots that have been revealed by infrared imaging during inspection. The implications of connector aging is two-fold: (1) significant increases in resistivity of the splice connector (i.e., less efficient transmission of electricity) and (2) significant reductions in the connector clamping strength, which could ultimately result in separation of the power transmission line at the joint. Therefore, the splice connector appears to be the weakest link in electric power transmission lines. This report presents a protocol for integrating analytical and experimental approaches to evaluate the integrity of full tension single-stage splice connector assemblies and the associated effective lifetime at high operating temperature.

  3. High-Performing, Low-Temperature-Operating, Long-Lifetime Aerospace Lubricants

    Science.gov (United States)

    Joshi, Prakash

    2015-01-01

    Long-duration space exploration will require spacecraft systems that can operate effectively over several years with minimal or no maintenance. Aerospace lubricants are key components of spacecraft systems. Physical Sciences Inc., has synthesized and characterized novel ionic liquids for use in aerospace lubricants that contribute to decreased viscosity, friction, and wear in aerospace systems. The resulting formulations offer low vapor pressure and outgassing properties and thermal stability up to 250 C. They are effective for use at temperatures as low as -70 C and provide long-term operational stability in aerospace systems. In Phase II, the company scaled several new ionic liquids and evaluated a novel formulation in a NASA testbed. The resulting lubricant compounds will offer lower volatility, decreased corrosion, and better tribological characteristics than standard liquid lubricants, particularly at lower temperatures.

  4. Improved cycling behavior of ZEBRA battery operated at intermediate temperature of 175°C

    Energy Technology Data Exchange (ETDEWEB)

    Li, Guosheng; Lu, Xiaochuan; Kim, Jin Yong; Lemmon, John P.; Sprenkle, Vincent L.

    2014-03-01

    Operation of sodium-nickel chloride battery at temperatures lower than 200°C reduces cell degradation and improves the cyclability. One of the main technical issues in terms of operating this battery at intermediate temperatures such as 175°C is the poor wettability of molten sodium on β”-alumina solid electrolyte (BASE) causing reduced active area and limited charging . In order to overcome the problem related to poor wettability of Na melt on BASE at 175°C, Pt grid was applied on the anode side of BASE using a screen printing technique. Deeper charging and improved cycling behavior was observed on the cells with metalized BASEs due to extended active area.

  5. INFLUENCE OF FUEL TEMPERATURE ON DIESEL ENGINE PERFORMANCE OPERATING WITH BIODIESEL BLEND

    Directory of Open Access Journals (Sweden)

    Rafidah Rahim

    2012-06-01

    Full Text Available This paper presents the study of the effect of temperature on diesel engine performance using a 5% biodiesel blend. A one-dimensional numerical analysis is used to simulate the four-cylinder diesel engine. The diesel engine simulation is used to study the characteristics of engine performance when the engine is operating with a fuel blend as an alternative fuel. The simulations are conducted at full load conditions where the temperature varies from 300 to 500 K. The results show that the maximum brake power and brake torque reduction was 1.39% and 1.13%, respectively for an engine operating with a fuel blend. It is shown that the insignificant different due to the small gap between energy content values. A decrease in the lower heating value caused an increase in the brake specific fuel consumption and thus, a reduction in the brake thermal efficiency of the engine performance at full load.

  6. Moderate-temperature operable SO2 gas sensor based on Zr4+ ion conducting solid electrolyte

    Directory of Open Access Journals (Sweden)

    Y. Uneme

    2012-12-01

    Full Text Available A solid electrolyte type sulfur dioxide (SO2 gas sensor that can operate at moderate temperatures was fabricated using Zr4+ ion conducting Zr39/40TaP2.9W0.1O12 solid electrolyte with 0.7La2O2SO4 − 0.3(0.8Li2SO4 + 0.2K2SO4 having a large surface area and Zr metal as the auxiliary sensing electrode and reference electrode, respectively. Since the present sensor showed a quantitative, reproducible and rapid response which obeys the theoretical Nernst relationship even at 400 °C, it is a potential on site SO2 gas sensing tool operable at moderate temperatures around 400 °C.

  7. Meniscal Ramp Lesions: Anatomy, Incidence, Diagnosis, and Treatment.

    Science.gov (United States)

    Chahla, Jorge; Dean, Chase S; Moatshe, Gilbert; Mitchell, Justin J; Cram, Tyler R; Yacuzzi, Carlos; LaPrade, Robert F

    2016-07-01

    Meniscal ramp lesions are more frequently associated with anterior cruciate ligament (ACL) injuries than previously recognized. Some authors suggest that this entity results from disruption of the meniscotibial ligaments of the posterior horn of the medial meniscus, whereas others support the idea that it is created by a tear of the peripheral attachment of the posterior horn of the medial meniscus. Magnetic resonance imaging (MRI) scans have been reported to have a low sensitivity, and consequently, ramp lesions often go undiagnosed. Therefore, to rule out a ramp lesion, an arthroscopic evaluation with probing of the posterior horn of the medial meniscus should be performed. Several treatment options have been reported, including nonsurgical management, inside-out meniscal repair, or all-inside meniscal repair. In cases of isolated ramp lesions, a standard meniscal repair rehabilitation protocol should be followed. However, when a concomitant ACL reconstruction (ACLR) is performed, the rehabilitation should follow the designated ACLR postoperative protocol. The purpose of this article was to review the current literature regarding meniscal ramp lesions and summarize the pertinent anatomy, biomechanics, diagnostic strategies, recommended treatment options, and postoperative protocol.

  8. A RAMP CODE FOR FINE-GRAINED ACCESS CONTROL

    Directory of Open Access Journals (Sweden)

    Kannan Karthik

    2013-02-01

    Full Text Available Threshold ramp secret sharing schemes are designed so that (i certain subsets of shares have no information about the secret, (ii some subsets have partial information about the secret and (iii some subsets have complete information to recover the secret. However most of the ramp schemes in present literature do not control the leakage of information in partial access sets, due to which the information acquired by these sets is devoid of structure and not useful for fine-grained access control. Through a non-perfect secret sharing scheme called MIX-SPLIT, an encoding methodology for controlling the leakage in partial access sets is proposed and this is used for fine-grained access to binary strings. The ramp code generated using MIX-SPLIT requires a much smaller share size of O(n, as compared to Shamir's ramp adaptation which incurs a share size of atleast O(n2 for the same multi-access structure. The proposed ramp code is finally applied towards the protection and fine-grained access of industrial design drawings.

  9. Continuous-wave operation of a room-temperature Tm: YAP-pumped Ho: YAG laser

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    We report a continuous-wave (CW) 2.1-μm Ho:YAG laser operating at room temperature pumped by a diode-pumped 1.94-?m Tm:YAP laser.The maximum output power of 1.5 W is obtained from Ho:YAG laser,corresponding to Tm-to-Ho slope efficiency of 17.9% and diode-to-He conversion efficiency of 5.6%.

  10. Study of fuel inlet temperature variations on palm biodiesel operating with a diesel engine

    Directory of Open Access Journals (Sweden)

    Mat Yasin Mohd Hafizil

    2017-01-01

    Full Text Available Biofuel includes biodiesel is introduced to overcome the air pollution problems. Biodiesel is the sustainable and alternative fuel that derived from edible and non-edible oil produced from bio-originated species, plants, and animals. This paper presents the simulation analysis on the effect of fuel temperature variations on diesel engine performance and emission using palm-biodiesel. A one-dimensional numerical analysis, Diesel RK software is used to simulate a single cylinder, four-stroke diesel engine on the performance and emission when operated at a full load condition using fuel temperature variations ranging 300 K to 333 K. Results showed that simulated results for brake power and brake torque were 0.7% each when compared to the highest and lowest fuel temperature ranging from 333 K to 300 K. Moreover, higher fuel temperature for palm biodiesel tends to produce lower exhaust gas temperature and brake specific fuel consumption at a constant engine speed of 2400 rpm. It can be concluded that from the study, fuel temperature variations of biodiesel could produce a significant effect regarding engine performance and emission that influence the driving economy of the engine.

  11. Effect of operating temperature on the HWB model for solar-collector design

    Science.gov (United States)

    Huang, H.; Howell, J. R.

    1983-02-01

    The Hottel-Whillier-Bliss (HWB) Model for the thermal efficiency of a flat plate solar collector plots as a straight line in an esa/sub c/ approx. (T/sub f,in/ - T/sub a/)/g/sub s/ coordinate system under the following assumptions: (1) the effect of the thermal capacity in the collector is negligible; (2) F/sub R/, U/sub L/ are constant in the range of operating temperature. These assumptions simplify the model and make it convenient to use. Because of the intermittance of insulation and the variation of ambient temperature and wind speed, the thermal capacity of the collector may affect the transient efficiency of the collector. In addition, the values of F/sub R/ and U/sub L/ are actually not constant and cause deviation of the efficiency curve from a straight line. The concern is with the deviation of the confidence level for a specific operating range. The effect of operating temperature of the values of F/sub R/ and U/sub L/ is discussed.

  12. Green monolithic II-VI vertical-cavity surface-emitting laser operating at room temperature

    Science.gov (United States)

    Kruse, C.; Ulrich, S. M.; Alexe, G.; Roventa, E.; Kröger, R.; Brendemühl, B.; Michler, P.; Gutowski, J.; Hommel, D.

    2004-02-01

    The realization of a monolithic all II-VI-based vertical cavity surface emitting laser (VCSEL) for the green spectral region is reported. Optically pumped lasing operation was achieved up to room temperature using a planar VCSEL structure. Taking advantage of distributed Bragg-reflectors based on MgS/Zn(Cd)Se superlattices as the low-refractive index material and ZnS0.06Se0.94 layers as the high-index material with a refractive index contrast of n = 0.6, a quality factor exceeding Q = 2000 is reached by using only 18 Bragg periods for the bottom DBR and 15 Bragg periods for the top DBR. The threshold power density is 0.32 MW/cm2 at a temperature of 10 K (emission wavelength 498.5 nm) and 1.9 MW/cm2 at room temperature (emission wavelength 502.3 nm).

  13. Numerical study of high-power semiconductor lasers for operation at sub-zero temperatures

    Science.gov (United States)

    Hasler, K. H.; Frevert, C.; Crump, P.; Erbert, G.; Wenzel, H.

    2017-04-01

    We present results on the impact of the Al-content in the waveguide structure on the electro-optical characteristics of 9xx nm, GaAs-based high-power lasers operated at room (300 K) and at sub-zero (200 K) heat sink temperatures. Experimentally a strong improvement of conversion efficiency and output power has been found if the lasers are cooled down. Numerical simulations using a software tool which solves the thermo-dynamic based drift-diffusion equations are able to reproduce the experimental findings. The reasons for the improved performance at lower temperatures are the enhancement of the modal gain and the reduced accumulation of electrons in the p-confinement layers resulting in a reduction of the leakage current. The latter allows the realization of lasers with a reduced Al content having a smaller series resistance and thus further enlarged conversion efficiency at sub-zero temperatures.

  14. Investigating the temperature dependence of photomultiplier quantum efficiency when operating in the visible spectrum

    CERN Document Server

    Clawson, Savannah Ellen

    2017-01-01

    The quantum efficiency of a Burle 8850 photomultiplier tube with a potassium-caesium-antimony (bialkali) photocathode was determined by attenuating a 1 mW HeNe laser emitting at 633 nm and measuring the signal frequency when the laser was incident on the photomultiplier. A temperature range of 5 $^{\\circ}$C $-$ 20 $^{\\circ}$C was investigated and it was found that the quantum efficiency decreases with temperature, with the signal frequency decreasing at a faster rate than the dark current frequency. Therefore, it was concluded that it would not be beneficial to cool photomultiplier tubes operating in the visible spectrum for use in collinear laser spectroscopy due to a decreasing signal-to-noise ratio. The signal pulse height distribution was also analysed and found to be independent of temperature within the range investigated.

  15. HIGH COOLING WATER TEMPERATURE EFFECTS ON DESIGN AND OPERATIONAL SAFETY OF NPPS IN THE GULF REGION

    Directory of Open Access Journals (Sweden)

    BYUNG KOO KIM

    2013-12-01

    Full Text Available The Arabian Gulf region has one of the highest ocean temperatures, reaching above 35 degrees and ambient temperatures over 50 degrees in the summer. Two nuclear power plants (NPP are being introduced in the region for the first time, one at Bushehr (1,000 MWe PWR plant from Russia, and a much larger one at Barakah (4X1,400 MWe PWR from Korea. Both plants take seawater from the Gulf for condenser cooling, having to modify the secondary/tertiary side cooling systems design by increasing the heat transfer surface area from the country of origin. This paper analyses the secondary side of a typical PWR plant operating under the Rankine cycle with a simplified thermal-hydraulic model. Parametric study of ocean cooling temperatures is conducted to estimate thermal efficiency variations and its associated design changes for the secondary side. Operational safety is reviewed to deliver rated power output with acceptable safety margins in line with technical specifications, mainly in the auxiliary systems together with the cooling water temperature. Impact on the Gulf seawater as the ultimate heat sink is considered negligible, affecting only the adjacent water near the NPP site, when compared to the solar radiation on the sea surface.

  16. Electrolytes for Low-Temperature Operation of Li-CFx Cells

    Science.gov (United States)

    Smart, Marshall C.; Whitacre, Jay F.; Bugga, Ratnakumar V.; Prakash, G. K. Surya; Bhalla, Pooja; Smith, Kiah

    2009-01-01

    A report describes a study of electrolyte compositions selected as candidates for improving the low-temperature performances of primary electrochemical cells that contain lithium anodes and fluorinated carbonaceous (CFx) cathodes. This study complements the developments reported in Additive for Low-Temperature Operation of Li-(CF)n Cells (NPO- 43579) and Li/CFx Cells Optimized for Low-Temperature Operation (NPO- 43585), which appear elsewhere in this issue of NASA Tech Briefs. Similar to lithium-based electrolytes described in several previous NASA Tech Briefs articles, each of these electrolytes consisted of a lithium salt dissolved in a nonaqueous solvent mixture. Each such mixture consisted of two or more of the following ingredients: propylene carbonate (PC); 1,2-dimethoxyethane (DME); trifluoropropylene carbonate; bis(2,2,2-trifluoroethyl) ether; diethyl carbonate; dimethyl carbonate; and ethyl methyl carbonate. The report describes the physical and chemical principles underlying the selection of the compositions (which were not optimized) and presents results of preliminary tests made to determine effects of the compositions upon the low-temperature capabilities of Li-CFx cells, relative to a baseline composition of LiBF4 at a concentration of 1.0 M in a solvent comprising equal volume parts of PC and DME.

  17. Electron density and temperature in NIO1 RF source operated in oxygen and argon

    Science.gov (United States)

    Barbisan, M.; Zaniol, B.; Cavenago, M.; Pasqualotto, R.; Serianni, G.; Zanini, M.

    2017-08-01

    The NIO1 experiment, built and operated at Consorzio RFX, hosts an RF negative ion source, from which it is possible to produce a beam of maximum 130 mA in H- ions, accelerated up to 60 kV. For the preliminary tests of the extraction system the source has been operated in oxygen, whose high electronegativity allows to reach useful levels of extracted beam current. The efficiency of negative ions extraction is strongly influenced by the electron density and temperature close to the Plasma Grid, i.e. the grid of the acceleration system which faces the source. To support the tests, these parameters have been measured by means of the Optical Emission Spectroscopy diagnostic. This technique has involved the use of an oxygen-argon mixture to produce the plasma in the source. The intensities of specific Ar I and Ar II lines have been measured along lines of sight close to the Plasma Grid, and have been interpreted with the ADAS package to get the desired information. This work will describe the diagnostic hardware, the analysis method and the measured values of electron density and temperature, as function of the main source parameters (RF power, pressure, bias voltage and magnetic filter field). The main results show that not only electron density but also electron temperature increase with RF power; both decrease with increasing magnetic filter field. Variations of source pressure and plasma grid bias voltage appear to affect only electron temperature and electron density, respectively.

  18. Speed limit and ramp meter control for traffic flow networks

    Science.gov (United States)

    Goatin, Paola; Göttlich, Simone; Kolb, Oliver

    2016-07-01

    The control of traffic flow can be related to different applications. In this work, a method to manage variable speed limits combined with coordinated ramp metering within the framework of the Lighthill-Whitham-Richards (LWR) network model is introduced. Following a 'first-discretize-then-optimize' approach, the first order optimality system is derived and the switch of speeds at certain fixed points in time is explained, together with the boundary control for the ramp metering. Sequential quadratic programming methods are used to solve the control problem numerically. For application purposes, experimental setups are presented wherein variable speed limits are used as a traffic guidance system to avoid traffic jams on highway interchanges and on-ramps.

  19. PDR with a Foot-Mounted IMU and Ramp Detection

    Directory of Open Access Journals (Sweden)

    Jorge Guevara

    2011-09-01

    Full Text Available The localization of persons in indoor environments is nowadays an open problem. There are partial solutions based on the deployment of a network of sensors (Local Positioning Systems or LPS. Other solutions only require the installation of an inertial sensor on the person’s body (Pedestrian Dead-Reckoning or PDR. PDR solutions integrate the signals coming from an Inertial Measurement Unit (IMU, which usually contains 3 accelerometers and 3 gyroscopes. The main problem of PDR is the accumulation of positioning errors due to the drift caused by the noise in the sensors. This paper presents a PDR solution that incorporates a drift correction method based on detecting the access ramps usually found in buildings. The ramp correction method is implemented over a PDR framework that uses an Inertial Navigation algorithm (INS and an IMU attached to the person’s foot. Unlike other approaches that use external sensors to correct the drift error, we only use one IMU on the foot. To detect a ramp, the slope of the terrain on which the user is walking, and the change in height sensed when moving forward, are estimated from the IMU. After detection, the ramp is checked for association with one of the existing in a database. For each associated ramp, a position correction is fed into the Kalman Filter in order to refine the INS-PDR solution. Drift-free localization is achieved with positioning errors below 2 meters for 1,000-meter-long routes in a building with a few ramps.

  20. High temperature operation In1-xAlxSb infrared focal plane

    Science.gov (United States)

    Lyu, Yanqiu; Si, Junjie; Cao, Xiancun; Zhang, Liang; Peng, Zhenyu; Ding, Jiaxin; Yao, Guansheng; Zhang, Xiaolei; Reobrazhenskiy, Valeriy

    2016-05-01

    A high temperature operation mid-wavelength 128×128 infrared focal plane arrays (FPA) based on low Al component In1-xAlxSb was presented in this work. InAlSb materials were grown on InSb (100) substrates using MBE technology, which was confirmed by XRD and AFM analyses. We have designed and grown two structures with and without barrier. The pixel of the detector had a conventional PIN structure with a size of 50μmx50μm. The device fabrication process consisted of mesa etching, passivation, metallization and flip-chip hybridization with readout integrated circuit (ROIC), epoxy backfill, lap and polish. Diode resistance, imaging, NETD and operability results are presented for a progression of structures that reduce the diode leakage current as the temperature is raised above 80K. These include addition of a thin region of InAlSb to reduce p-contact leakage current, and construction of the whole device from InAlSb to reduce thermal generation in the active region of the detector. An increase in temperature to 110K, whilst maintaining full 80K performance, is achieved. The I-V curves were measured at different temperature. Quantum efficiency, pixel operability, non-uniformity, and the mean NETD values of the FPAs were measured at 110K. This gives the prospect of significant benefits for the cooling systems, including, for example, use of argon in Joule-Thomson coolers or an increase in the life and/or decrease in the cost, power consumption and cool-down time of Stirling engines by several tens of percent.

  1. 2-D Electromagnetic Model of Fast-Ramping Superconducting Magnets

    CERN Document Server

    Auchmann, B; Kurz, S; Russenschuck, Stephan

    2006-01-01

    Fast-ramping superconducting (SC) accelerator magnets are the subject of R&D efforts by magnet designers at various laboratories. They require modifications of magnet design tools such as the ROXIE program at CERN, i.e. models of dynamic effects in superconductors need to be implemented and validated. In this paper we present the efforts towards a dynamic 2-D simulation of fast-ramping SC magnets with the ROXIE tool. Models are introduced and simulation results are compared to measurements of the GSI001 magnet of a GSI test magnet constructed and measured at BNL.

  2. Operating Cell Temperature Determination in Flat-Plate Photovoltaic Modules; Calculo de la Temperature de Operacion de Celulas Solares en un Panel Fotovoltaico Plano

    Energy Technology Data Exchange (ETDEWEB)

    Chenlo, F.

    2002-07-01

    Two procedures (simplified and complete) to determine the operating cell temperature in photovoltaic modules operating in real conditions assuming isothermal stationary modules are presented in this work. Some examples are included that show the dependence of this temperature on several environment (sky, ground and ambient temperatures, solar irradiance, wind speed, etc.) and structural (module geometry and size, encapsulating materials, antirreflexive optical coatings, etc) factors and also on electrical module performance. In a further step temperature profiles for non-isothermal modules are analysed besides transitory effects due to variable irradiance and wind gusts. (Author)

  3. Impact of Radiation Hardness and Operating Temperatures of Silicon Carbide Electronics on Space Power System Mass

    Science.gov (United States)

    Juhasz, Albert J.; Tew, Roy C.; Schwarze, Gene E.

    1998-01-01

    The effect of silicon carbide (SiC) electronics operating temperatures on Power Management and Distribution (PMAD), or Power Conditioning (PC), subsystem radiator size and mass requirements was evaluated for three power output levels (100 kW(e) , 1 MW(e), and 10 MW(e)) for near term technology ( i.e. 1500 K turbine inlet temperature) Closed Cycle Gas Turbine (CCGT) power systems with a High Temperature Gas Reactor (HTGR) heat source. The study was conducted for assumed PC radiator temperatures ranging from 370 to 845 K and for three scenarios of electrical energy to heat conversion levels which needed to be rejected to space by means of the PC radiator. In addition, during part of the study the radiation hardness of the PC electronics was varied at a fixed separation distance to estimate its effect on the mass of the instrument rated reactor shadow shield. With both the PC radiator and the conical shadow shield representing major components of the overall power system the influence of the above on total power system mass was also determined. As expected, results show that the greatest actual mass savings achieved by the use of SiC electronics occur with high capacity power systems. Moreover, raising the PC radiator temperature above 600 K yields only small additional system mass savings. The effect of increased radiation hardness on total system mass is to reduce system mass by virtue of lowering the shield mass.

  4. Fuzzy self-tuning PID control of the operation temperatures in a two-staged membrane separation process

    Institute of Scientific and Technical Information of China (English)

    Lei Wang; Wencai Du; Hai Wang; Hong Wu

    2008-01-01

    A two-staged membrane separation process for hydrogen recovery from refinery gases is introduced. The principle of the gas membrane separation process and the influence of the operation temperatures are analyzed. As the conventional PID controller is difficult to make the operation temperatures steady, a fuzzy self-tuning PID control algorithm is proposed. The application shows that the algorithm is effective, the operation temperatures of both stages can be controlled steadily, and the operation flexibility and adaptability of the hydrogen recovery unit are enhanced with safety. This study lays a foundation to optimize the control of the membrane separation process and thus ensure the membrane performance.

  5. A New Operational Snow Retrieval Algorithm Applied to Historical AMSR-E Brightness Temperatures

    Directory of Open Access Journals (Sweden)

    Marco Tedesco

    2016-12-01

    Full Text Available Snow is a key element of the water and energy cycles and the knowledge of spatio-temporal distribution of snow depth and snow water equivalent (SWE is fundamental for hydrological and climatological applications. SWE and snow depth estimates can be obtained from spaceborne microwave brightness temperatures at global scale and high temporal resolution (daily. In this regard, the data recorded by the Advanced Microwave Scanning Radiometer—Earth Orbiting System (EOS (AMSR-E onboard the National Aeronautics and Space Administration’s (NASA AQUA spacecraft have been used to generate operational estimates of SWE and snow depth, complementing estimates generated with other microwave sensors flying on other platforms. In this study, we report the results concerning the development and assessment of a new operational algorithm applied to historical AMSR-E data. The new algorithm here proposed makes use of climatological data, electromagnetic modeling and artificial neural networks for estimating snow depth as well as a spatio-temporal dynamic density scheme to convert snow depth to SWE. The outputs of the new algorithm are compared with those of the current AMSR-E operational algorithm as well as in-situ measurements and other operational snow products, specifically the Canadian Meteorological Center (CMC and GlobSnow datasets. Our results show that the AMSR-E algorithm here proposed generally performs better than the operational one and addresses some major issues identified in the spatial distribution of snow depth fields associated with the evolution of effective grain size.

  6. Non-isentropic layers in matter behind shock and ramp compression waves

    CERN Document Server

    Khishchenko, Konstantin V

    2014-01-01

    According to the ideal fluid dynamics approach, the temperature and entropy values of a medium undergo a jump increase in the shock front as well as on contact interface between different materials after the shock wave propagation, but remain constant behind the shock front out of the contact interface. In the real condensed matter, the shock fronts and transition regions near the interfaces have finite thicknesses; therefore, the temperature field is disturbed around the interfaces. In this work, such disturbances are numerically analyzed for the problems of formation of the steady shock wave at impact and ramp loading of metals, reflection of the steady shock wave from a free surface, and the shock wave passing through the interface between two different materials. Theoretical analysis and computations show that the non-isentropic layers (the high-entropy ones with the increased temperature and the low-entropy ones with the decreased temperature) arise near the interfaces in the above problems of shock and ...

  7. High Operating Temperature and Low Power Consumption Boron Nitride Nanosheets Based Broadband UV Photodetector

    Science.gov (United States)

    Rivera, Manuel; Velázquez, Rafael; Aldalbahi, Ali; Zhou, Andrew F.; Feng, Peter

    2017-03-01

    We extend our work on the use of digitally controlled pulsed laser plasma deposition (PLPD) technique to synthesize high quality, 2-dimensional single crystalline boron nitride nanosheets (BNNSs) at a low substrate temperature for applications in high-performance deep UV photodetectors. The obtained sample consists of a large amount of BNNSs partially overlapping one another with random orientations. Each sheet is composed of a few (from 2 to 10) stacked atomic layers exhibiting high transparency due to its highly ordered hBN crystallinity. Deep UV detectors based on the obtained BNNSs were designed, fabricated, and tested. The bias and temperature effects on the photocurrent strength and the signal-to-noise ratio have been carefully characterized and discussed. A significant shift in the cut off wavelength of the BNNSs based photodetectors was observed suggesting a band gap reduction as a result of the BNNSs’ collective structure. The newly designed photodetector presented exceptional properties: a high sensitivity to weak intensities of radiation in both UVC and UVB range while remaining visible-blind, and a high signal-to-noise ratio operation even at temperatures as high as 400 °C. In addition, the BNNSs based photodetector exhibited potential for self-powered operation.

  8. Modeling of thermoelectric module operation in inhomogeneous transient temperature field using finite element method

    Directory of Open Access Journals (Sweden)

    Nikolić Radovan H.

    2014-01-01

    Full Text Available This paper is the result of research and operation modeling of the new systems for cooling of cutting tools based on thermoelectric module. A copper inlay with thermoelectric module on the back side was added to a standard turning tool for metal processing. For modeling and simulating the operation of thermoelectric module, finite element method was used as a method for successful solving the problems of inhomogeneous transient temperature field on the cutting tip of lathe knives. Developed mathematical model is implemented in the software package PAK-T through which numerical results are obtained. Experimental research was done in different conditions of thermoelectric module operation. Cooling of the hot module side was done by a heat exchanger based on fluid using automatic temperature regulator. After the calculation is done, numerical results are in good agreement with experimental. It can be concluded that developed mathematical model can be used successfully for modeling of cooling of cutting tools. [Projekat Ministarstva nauke Republike Srbije, br. TR32036

  9. High ramp rate thermogravimetric analysis of zirconium(II) hydride and titanium(II) hydride

    Energy Technology Data Exchange (ETDEWEB)

    Licavoli, Joseph J., E-mail: jjlicavo@mtu.edu; Sanders, Paul G., E-mail: sanders@mtu.edu

    2015-09-20

    Highlights: • A unique arc image device has been proposed for high ramp rate thermogravimetry. • Powder oxidation influences decomposition kinetics at temperatures below 933 K. • Particle size has a negligible effect on TiH{sub 2} decomposition behavior. • Improvements to the device are required to conduct accurate kinetic analysis. - Abstract: Zirconium and titanium hydride are utilized in liquid phase metal foam processing techniques. This application results in immediate exposure to molten metal and almost immediate decomposition at high temperatures. Most decomposition characterization techniques utilize slow heating rates and are unable to capture the decomposition behavior of hydrides under foam processing conditions. In order to address this issue a specialized high ramp rate thermogravimetric analyzer was created from a xenon arc image refiner. In addition to thermogravimetry, complimentary techniques including X-ray diffraction and scanning electron microscopy were used to characterize hydride decomposition and compare the results to literature. Hydrides were partially oxidized and separated into particles size ranges to evaluate the influence of these factors on decomposition. Oxidizing treatments were found to decrease decomposition rate only at temperatures below 933 K (660 °C) while particle size effects appeared to be negligible. Several improvements to the unique TGA apparatus presented in the current work are suggested to allow reliable kinetic modeling and analysis.

  10. Above room temperature continuous wave operation of a broad-area quantum-cascade laser

    Science.gov (United States)

    Semtsiv, M. P.; Masselink, W. T.

    2016-11-01

    We describe the design and implementation of a broad-area (w ≈ 30 μm) quantum-cascade laser operating in a continuous wave mode up to heat-sink temperatures beyond +100 °C. The room-temperature emission wavelength is 4.6 μm. The temperature gradient in the active region of such a wide laser stripe is essentially perpendicular to the epitaxial layers and the resulting steady-state active region temperature offset scales approximately with the square of the number of cascades. With only 10 cascades in the active region, the threshold electrical power density in the current quantum-cascade laser in the continuous-wave mode is as low as Vth × Ith = 3.8 V × 0.9 kA/cm2 = 3.4 kW/cm2 at room temperature for 2 mm-long two-side high-reflectivity coated laser stripe. A 4 mm-long one-side high-reflectivity coated laser stripe delivers in continuous-wave mode above 0.6 W at +20 °C and above 1.3 W at -27 °C (cooled with a single-stage Peltier element). A 2 mm-long two-side high-reflectivity coated laser stripe demonstrates continuous-wave lasing up to at least +102 °C (375 K). The thermal conductance, Gth, ranges between 235 W/K cm2 and 140 W/K cm2 for temperatures between -33 °C and +102 °C. This demonstration opens the route for continuous-wave power scaling of quantum-cascade lasers via broad-area laser ridges.

  11. Feasibility study of SiGHT: a novel ultra low background photosensor for low temperature operation

    CERN Document Server

    Wang, Yi; Fiorillo, Giuliana; Galbiati, Cristiano; Guan, Meng-Yun; Korga, George; Pantic, Emilija; Razeto, Alessandro; Renshaw, Andrew; Rossi, Biagio; Suvorov, Yury; Wang, Hanguo; Yang, Chang-Gen

    2016-01-01

    Rare event search experiments, such as those searching for dark matter and observations of neutrinoless double beta decay, require ultra low levels of radioactive background for unmistakable identification. In order to reduce the radioactive backgrounds of detectors used in these types of event searches, low background photosensors are required, as the physical size of these detectors become increasing larger, and hence the number of such photosensors used also increases rapidly. Considering that most dark matter and neutrinoless double beta decay experiments are turning towards using noble liquids as the target choice, liquid xenon and liquid argon for instance, photosensors that can work well at cryogenic temperatures are required, 165 K and 87 K for liquid xenon and liquid argon, respectively. The Silicon Geiger Hybrid Tube (SiGHT) is a novel photosensor designed specifically for use in ultra low background experiments operating at cryogenic temperatures. It is based on the proven photocathode plus silicon...

  12. The Effect Of Temperature On The Performance Of PV Array Operating Under Concentration

    Directory of Open Access Journals (Sweden)

    Eng. Sameh. M.El Sayed

    2015-08-01

    Full Text Available Abstract The sun is the worlds sole source of energy. In fact all of the energy being used on the earth today is driven from solar energy. Because of the increase in world energy demand and the threat of global warming there is a pressing need for the development of reliable cost-effective sources of renewable energy. Renewable energy sources include indirect solar energy such as hydro wind and direct solar energy conversion through thermal receivers or photovoltaic. This paper discusses the parameters that affects on the cell temperature under concentration. Comparison between fixed modules and solar cells operating under concentration to get the optimum solution. By increasing the concentration factor one minimizes the area of the cell .System uses special cell Fresnel lens and multilayer cells.This cell has large efficiency and bear high temperature. The economic studies are necessary to calculate the cost of 1kwh for each case.

  13. Room-temperature operation of a titanium supersaturated silicon-based infrared photodetector

    Science.gov (United States)

    García-Hemme, E.; García-Hernansanz, R.; Olea, J.; Pastor, D.; del Prado, A.; Mártil, I.; González-Díaz, G.

    2014-05-01

    We report room-temperature operation of 1 × 1 cm2 infrared photoconductive photodetectors based on silicon supersaturated with titanium. We have fabricated these Si-based infrared photodetectors devices by means of ion implantation followed by a pulsed laser melting process. A high sub-band gap responsivity of 34 mV W-1 has been obtained operating at the useful telecommunication applications wavelength of 1.55 μm (0.8 eV). The sub-band gap responsivity shows a cut-off frequency as high as 1.9 kHz. These Si-based devices exhibit a non-previous reported specific detectivity of 1.7 × 104 cm Hz1/2 W-1 at 660 Hz, under a 1.55 μm wavelength light. This work shows the potential of Ti supersaturated Si as a fully CMOS-compatible material for the infrared photodetection technology.

  14. [Evaluation of operation ergonomics at high-temperature in the cockpit].

    Science.gov (United States)

    Tian, Yinsheng; Li, Jing; Ding, Li; Wang, Qiong; Ren, Zhaosheng; Shi, Liyong; Xue, Lihao

    2011-08-01

    10 male subjects participated in the environmental simulation study to evaluate the operation ergonomics at high-temperature in the cockpit. Grip strength, perception, dexterity, reaction and intelligence were measured respectively during the tests at 40 degrees C and 45 degrees C, simulating the high-temperatures in a simulation cockpit chamber. Then the data obtained were compared to the combined index of heat stress (CIHS). The average values of each item of the subjects' performance at the two different temperatures are compared. The results indicated that CIHS exceeded the heat stress safety line after 45 min at 40 degrees C, grip strength decreased by 12%, and perception increased by 2.89 times. In contrast, at 45 degrees C, CIHS exceeded the safety line after 20 min, grip strength decreased by 3.2%, and perception increased by 4.36 times. However, Finger dexterity was less affected. Reaction ability was first accelerated, and then slowed down. The error rate in the intelligence test increased to a greater extent. At the high temperatures, the minimum perception was the most affected, followed by grip strength, reaction and finger dexterity were less affected, while the intelligence did not decline, but rise.

  15. Helium-filled proportional counter and its operation mechanism at low temperatures

    CERN Document Server

    Isozumi, Y; Kishimoto, S

    2002-01-01

    The operation mechanism of helium-filled proportional counter (HFPC) at about 4.2 K is explained. Unstable behavior of HFPC is caused by releasing secondary-electron from the cathode by four kinds of active particles such as He sub n sup + , non-resonance photon from excited helium atom, non-resonance photon from He sub 2 sup * (A sup 1 Su sup +) and He sub 2 sup m (a sup 3 Su sup +). On experiments of HFPC behavior at low temperature, the following facts were observed; 1) main charge formation process in the electron avalanche is direct ionization by electron without Hornbeck-Molnar process. Accordingly, the gas amplification factor becomes small at low temperature. 2) Stable helium cation is He sub 2 sup + at room temperature, but cluster at low temperature. Large after-pulse is observed in output signal depends on cluster ion. The probability of secondary-electron emission decreased. The gas gain increased with increasing anode voltage. 3) By decreasing reaction rate of atom and molecule collision at low t...

  16. Room Temperature Operation of a Radiofrequency Diamond Magnetometer near the Shot Noise Limit

    CERN Document Server

    Shin, Chang S; Butler, Mark C; Trease, David R; Seltzer, Scott J; Mustonen, J Peter; Kennedy, Daniel J; Acosta, Victor M; Budker, Dmitry; Pines, Alexander; Bajaj, Vikram S

    2012-01-01

    We operate a nitrogen vacancy (NV-) diamond magnetometer at ambient temperatures and study the dependence of its bandwidth on experimental parameters including optical and microwave excitation powers. We introduce an analytical theory that yields an explicit formula for the response of an ensemble of NV- spins to an oscillating magnetic field, such as in NMR applications. We measure a detection bandwidth of 1.6 MHz and a sensitivity of 4.6 nT/Hz^(1/2), unprecedented in a detector with this active volume and close to the photon shot noise limit of our experiment.

  17. Experiencing Production Ramp-Up Education for Engineers

    Science.gov (United States)

    Bassetto, S.; Fiegenwald, V.; Cholez, C.; Mangione, F.

    2011-01-01

    This paper presents a game of industrialisation, based on a paper airplane, that mimics real world production ramp-up and blends classical engineering courses together. It is based on a low cost product so that it can be mass produced. The game targets graduate students and practitioners in engineering fields. For students, it offers an experiment…

  18. Cored Rutherford cables for the GSI fast ramping synchrotron

    NARCIS (Netherlands)

    Wilson, M.N.; Ghosh, A.K.; Haken, ten B.; Hassenzahl, W.V.; Kaugerts, J.; Moritz, G.; Muehle, C.; Ouden, den A.; Soika, R.; Wanderer, P.; Wessel, W.A.J.

    2003-01-01

    The new heavy ion synchrotron facility proposed by GSI will have two superconducting magnet rings in the same tunnel, with rigidities of 200 T/spl middot/m and 100 T/spl middot/m. Fast ramp times are needed, which can cause significant problems for the magnets, particularly in the areas of ac loss a

  19. Building Ramps and Hovercrafts and Improving Math Skills.

    Science.gov (United States)

    Bottge, Brian A.

    2001-01-01

    This article describes a video- and computer-based program used to motivate and develop mathematics skills in middle school students with disabilities. The program emphasizes real-life problems such as building a cage for a pet, a skate boarding ramp, and a "hovercraft" frame. Case studies illustrate the program's effectiveness with individual…

  20. 9 CFR 313.1 - Livestock pens, driveways and ramps.

    Science.gov (United States)

    2010-01-01

    ... animal may be injured shall be repaired. (b) Floors of livestock pens, ramps, and driveways shall be constructed and maintained so as to provide good footing for livestock. Slip resistant or waffled floor... the opinion of the inspector, to protect them from the adverse climatic conditions of the locale...

  1. Electromagnetic power absorption and temperature changes due to brain machine interface operation.

    Science.gov (United States)

    Ibrahim, Tamer S; Abraham, Doney; Rennaker, Robert L

    2007-05-01

    To fully understand neural function, chronic neural recordings must be made simultaneously from 10s or 100s of neurons. To accomplish this goal, several groups are developing brain machine interfaces. For these devices to be viable for chronic human use, it is likely that they will need to be operated and powered externally via a radiofrequency (RF) source. However, RF exposure can result in tissue heating and is regulated by the FDA/FCC. This paper provides an initial estimate of the amount of tissue heating and specific absorption rate (SAR) associated with the operation of a brain-machine interface (BMI). The operation of a brain machine interface was evaluated in an 18-tissue anatomically detailed human head mesh using simulations of electromagnetics and bio-heat phenomena. The simulations were conducted with a single chip, as well as with eight chips, placed on the surface of the human brain and each powered at four frequencies (13.6 MHz, 1.0 GHz, 2.4 GHz, and 5.8 GHz). The simulated chips consist of a wire antenna on a silicon chip covered by a Teflon dura patch. SAR values were calculated using the finite-difference time-domain method and used to predict peak temperature changes caused by electromagnetic absorption in the head using two-dimensional bio-heat equation. Results due to SAR alone show increased heating at higher frequencies, with a peak temperature change at 5.8 GHz of approximately 0.018 degrees C in the single-chip configuration and 0.06 degrees C in the eight-chip configuration with 10 mW of power absorption (in the human head) per chip. In addition, temperature elevations due to power dissipation in the chip(s) were studied. Results show that for the neural tissue, maximum temperature rises of 3.34 degrees C in the single-chip configuration and 7.72 degrees C in the eight-chip configuration were observed for 10 mW dissipation in each chip. Finally, the maximum power dissipation allowable in each chip before a 1.0 degrees C temperature

  2. A Coupled Model of Langmuir Circulations and Ramp-like Structures in the Upper Ocean Turbulent Boundary Layer

    Science.gov (United States)

    Soloviev, A.; Dean, C.; Lukas, R.; Donelan, M. A.; Terray, E. A.

    2016-12-01

    Surface-wave breaking is a powerful mechanism producing significant energy flux to small scale turbulence. Most of the turbulent energy produced by breaking waves dissipates within one significant wave height, while the turbulent diffusion layer extends to approximately ten significant wave heights. Notably, the near-surface shear may practically vanish within the wave-stirred layer due to small-scale turbulent mixing. The surface ocean temperature-salinity structure, circulation, and mass exchanges (including greenhouse gases and pollutants) substantially depend on turbulent mixing and non-local transport in the near-surface layer of the ocean. Spatially coherent organized motions have been recognized as an important part of non-local transport. Langmuir circulation (LC) and ramp-like structures are believed to vertically transfer an appreciable portion of the momentum, heat, gases, pollutants (e.g., oil), and other substances in the upper layer of the ocean. Free surface significantly complicates the analysis of turbulent exchanges at the air-sea interface and the coherent structures are not yet completely understood. In particular, there is growing observational evidence that in the case of developing seas when the wind direction may not coincide with the direction of the energy containing waves, the Langmuir lines are oriented in the wind rather than the wave direction. In addition, the vortex force due to Stokes drift in traditional models is altered in the breaking-wave-stirred layer. Another complication is that the ramp-like structures in the upper ocean turbulent boundary layer have axes perpendicular to the axes of LC. The ramp-like structures are not considered in the traditional model. We have developed a new model, which treats the LC and ramp-like structures in the near-surface layer of the ocean as a coupled system. Using computational fluid dynamics tools (LES), we have been able to reproduce both LC and ramp-like structures coexisting in space

  3. Striatal dopamine ramping may indicate flexible reinforcement learning with forgetting in the cortico-basal ganglia circuits

    Directory of Open Access Journals (Sweden)

    Kenji eMorita

    2014-04-01

    Full Text Available It has been suggested that the midbrain dopamine (DA neurons, receiving inputs from the cortico-basal ganglia (CBG circuits and the brainstem, compute reward prediction error (RPE, the difference between reward obtained or expected to be obtained and reward that had been expected to be obtained. These reward expectations are suggested to be stored in the CBG synapses and updated according to RPE through synaptic plasticity, which is induced by released DA. These together constitute the 'DA=RPE' hypothesis, which describes the mutual interaction between DA and the CBG circuits and serves as the primary working hypothesis in studying reward learning and value-based decision making. However, recent work has revealed a new type of DA signal that appears not to represent RPE. Specifically, it has been found in a reward-associated maze task that striatal DA concentration primarily shows a gradual increase towards the goal. We explored whether such ramping DA could be explained by extending the 'DA=RPE' hypothesis by taking into account biological properties of the CBG circuits. In particular, we examined effects of possible time-dependent decay of DA-dependent plastic changes of synaptic strengths by incorporating decay of learned values into the RPE-based reinforcement learning model and simulating reward learning tasks. We then found that incorporation of such a decay dramatically changes the model's behavior, causing gradual ramping of RPE. Moreover, we further incorporated magnitude-dependence of the rate of decay, which could potentially be in accord with some past observations, and found that near-sigmoidal ramping of RPE, resembling the observed DA ramping, could then occur. Given that synaptic decay can be useful for flexibly reversing and updating the learned reward associations, especially in case the baseline DA is low and encoding of negative RPE by DA is limited, the observed DA ramping would be indicative of the operation of such

  4. Striatal dopamine ramping may indicate flexible reinforcement learning with forgetting in the cortico-basal ganglia circuits.

    Science.gov (United States)

    Morita, Kenji; Kato, Ayaka

    2014-01-01

    It has been suggested that the midbrain dopamine (DA) neurons, receiving inputs from the cortico-basal ganglia (CBG) circuits and the brainstem, compute reward prediction error (RPE), the difference between reward obtained or expected to be obtained and reward that had been expected to be obtained. These reward expectations are suggested to be stored in the CBG synapses and updated according to RPE through synaptic plasticity, which is induced by released DA. These together constitute the "DA=RPE" hypothesis, which describes the mutual interaction between DA and the CBG circuits and serves as the primary working hypothesis in studying reward learning and value-based decision-making. However, recent work has revealed a new type of DA signal that appears not to represent RPE. Specifically, it has been found in a reward-associated maze task that striatal DA concentration primarily shows a gradual increase toward the goal. We explored whether such ramping DA could be explained by extending the "DA=RPE" hypothesis by taking into account biological properties of the CBG circuits. In particular, we examined effects of possible time-dependent decay of DA-dependent plastic changes of synaptic strengths by incorporating decay of learned values into the RPE-based reinforcement learning model and simulating reward learning tasks. We then found that incorporation of such a decay dramatically changes the model's behavior, causing gradual ramping of RPE. Moreover, we further incorporated magnitude-dependence of the rate of decay, which could potentially be in accord with some past observations, and found that near-sigmoidal ramping of RPE, resembling the observed DA ramping, could then occur. Given that synaptic decay can be useful for flexibly reversing and updating the learned reward associations, especially in case the baseline DA is low and encoding of negative RPE by DA is limited, the observed DA ramping would be indicative of the operation of such flexible reward learning.

  5. High-temperature passive direct methanol fuel cells operating with concentrated fuels

    Science.gov (United States)

    Zhao, Xuxin; Yuan, Wenxiang; Wu, Qixing; Sun, Hongyuan; Luo, Zhongkuan; Fu, Huide

    2015-01-01

    Conventionally, passive direct methanol fuel cells (DMFC) are fed with diluted methanol solutions and can hardly be operated at elevated temperatures (>120 °C) because the ionic conductivity of Nafion-type proton exchange membranes depends strongly on water content. Such a system design would limit its energy density and power density in mobile applications. In this communication, a passive vapor feed DMFC capable of operating with concentrated fuels at high temperatures is reported. The passive DMFC proposed in this work consists of a fuel reservoir, a perforated silicone sheet, a vapor chamber, two current collectors and a membrane electrode assembly (MEA) based on a phosphoric acid doped polybenzimidazole (PBI) membrane. The experimental results reveal that the methanol crossover through a PBI membrane is substantially low when compared with the Nafion membranes and the PBI-based passive DMFC can yield a peak power density of 37.2 mW cm-2 and 22.1 mW cm-2 at 180 °C when 16 M methanol solutions and neat methanol are used respectively. In addition, the 132 h discharge test indicates that the performance of this new DMFC is quite stable and no obvious performance degradation is observed after activation, showing its promising applications in portable power sources.

  6. Demonstration and Comparison of Operation of Photomultiplier Tubes at Liquid Argon Temperature

    CERN Document Server

    Acciarri, R; Boffelli, F; Cambiaghi, M; Canci, N; Cavanna, F; Cocco, A G; Di Pompeo, F; Fiorillo, G; Galbiati, C; Grandi, L; Kryczynski, P; Meng, G; Montanari, C; Palamara, O; Pandola, L; Perfetto, F; Mortari, G B Piano; Pietropaolo, F; Raselli, G L; Rossella, M; Rubbia, C; Segreto, E; Szelc, A M; Triossi, A; Ventura, S; Vignoli, C; Zani, A

    2011-01-01

    Liquified noble gases are widely used as a target in direct Dark Matter searches. Signals from scintillation in the liquid, following energy deposition from the recoil nuclei scattered by Dark Matter particles (e.g. WIMPs), should be recorded down to very low energies by photosensors suitably designed to operate at cryogenic temperatures. Liquid Argon based detectors for Dark Matter searches currently implement photo multiplier tubes for signal read-out. In the last few years PMTs with photocathodes operating down to liquid Argon temperatures (87 K) have been specially developed with increasing Quantum Efficiency characteristics. The most recent of these, Hamamatsu Photonics Mod. R11065 with peak QE up to about 35%, has been extensively tested within the R&D program of the WArP Collaboration. During these testes the Hamamatsu PMTs showed superb performance and allowed obtaining a light yield around 7 phel/keVee in a Liquid Argon detector with a photocathodic coverage in the 12% range, sufficient for detec...

  7. Low temperature operated NiO-SnO2 heterostructured SO2 gas sensor

    Science.gov (United States)

    Tyagi, Punit; Sharma, Anjali; Tomar, Monika; Gupta, Vinay

    2016-04-01

    Sulfur dioxide (SO2) is among the most toxic gas released by the industries which is extremely dangerous for human health. In the present communication, an attempt has been made for the detection of SO2 gas (500 ppm) with the help of SnO2 thin film based gas sensor. A low sensing response of 1.3 is obtained for sputtered SnO2 thin films based sensors at a high operating temperature of 220 °C. To improve the sensing response, different heterostructured sensors are developed by incorporating other metal oxide thin films (PdO, MgO, NiO, V2O5) over SnO2 thin film surface. Sensing response studies of different sensors towards SO2 gas (500 ppm) are presented in the present report. Among all the prepared sensors NiO-SnO2 hetero-structure sensor is showing highest sensing response (˜8) at a comparatively lower operating temperature (140 °C). Possible sensing mechanism for NiO-SnO2 heterostructured sensor has also been discussed in the present report.

  8. 30 CFR 56.9303 - Construction of ramps and dumping facilities.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Construction of ramps and dumping facilities... Loading, Hauling, and Dumping Safety Devices, Provisions, and Procedures for Roadways, Railroads, and Loading and Dumping Sites § 56.9303 Construction of ramps and dumping facilities. Ramps and...

  9. Modelling and operation of sub-miniature constant temperature hot-wire anemometry

    Science.gov (United States)

    Samie, M.; Watmuff, J. H.; Van Buren, T.; Hutchins, N.; Marusic, I.; Hultmark, M.; Smits, A. J.

    2016-12-01

    High-Reynolds number flows are very common in technological applications and in nature, and hot-wire anemometry is the preferred method for measuring the time-series of fluctuating velocity in such flows. However, measurement of very high-Reynolds number flows requires hot-wires with higher temporal and spatial resolution than is available with conventional probes. Much effort has therefore been devoted to decreasing the size of the hot-wire probes and this has led to associated challenges with operation. It is this latter operation problem which is the focus of this paper. To this end, an existing theoretical model of constant-temperature hot-wire anemometers (Perry 1982 Hot-Wire Anemometry (New York: Oxford University Press), Watmuff 1995 Exp. Therm. Fluid Sci. 11 117-34) is applied, and its accuracy is tested for the first time by comparison to measurements using an in-house constant temperature anemometer (CTA) for both conventional 5~μ m-diameter wires and sub-miniature hot-wires. With the aid of this model, we propose modifications to the CTA design and demonstrate successful operation of the CTA with the Princeton nano-scale thermal anemometry probe (NSTAP) (Bailey et al 2010 J. Fluid Mech. 663 160-79). It is also shown that the transfer function obtained from the model can be utilized to estimate the true frequency response and cut-off frequency of a hot-wire-CTA system to the velocity fluctuations, which is essential in accurate measurements of energy spectrum and higher order statistics of turbulent flows.

  10. High temperature operation of a composite membrane-based solid polymer electrolyte water electrolyser

    Energy Technology Data Exchange (ETDEWEB)

    Antonucci, V.; Di Blasi, A.; Baglio, V.; Arico, A.S. [CNR-ITAE, Via Salita S. Lucia sopra Contesse 5, 98126 Messina (Italy); Ornelas, R.; Matteucci, F. [Tozzi Apparecchiature Elettriche SpA, Via Zuccherificio, 10-48010 Mezzano (RA) (Italy); Ledesma-Garcia, J.; Arriaga, L.G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Parque Tecnologico Queretaro, Sanfandila, Pedro Escobedo, C.P. 76703 Queretaro (Mexico)

    2008-10-15

    The high temperature behaviour of a solid polymer electrolyte (SPE) water electrolyser based on a composite Nafion-SiO{sub 2} membrane was investigated and compared to that of a commercial Nafion membrane. The SPE water electrolyser performance was studied from 80 to 120{sup o}C with an operating pressure varying between 1 and 3 bar abs. IrO{sub 2} and Pt were used as oxygen and hydrogen evolution catalysts, respectively. The assemblies were manufactured by using a catalyst-coated membrane (CCM) technique. The performance was significantly better for the composite Nafion-SiO{sub 2} membrane than commercial Nafion 115. Furthermore, the composite membrane allowed suitable water electrolysis at high temperature under atmospheric pressure. The current densities were 2 and 1.2 A cm{sup -2} at a terminal voltage of 1.9 V for Nafion-SiO{sub 2} and Nafion 115, respectively, at 100{sup o}C and atmospheric pressure. By increasing the temperature up to 120{sup o}C, the performance of Nafion 115 drastically decreased; whereas, the cell based on Nafion-SiO{sub 2} membrane showed a further increase of performance, especially when the pressure was increased to 3 bar abs (2.1 A cm{sup -2} at 1.9 V). (author)

  11. Heat-driven thermoacoustic cryocooler operating at liquid hydrogen temperature with a unique coupler

    Science.gov (United States)

    Hu, J. Y.; Luo, E. C.; Li, S. F.; Yu, B.; Dai, W.

    2008-05-01

    A heat-driven thermoacoustic cryocooler is constructed. A unique coupler composed of a tube, reservoir, and elastic diaphragm is introduced to couple a traveling-wave thermoacoustic engine (TE) and two-stage pulse tube refrigerator (PTR). The amplitude of the pressure wave generated in the engine is first amplified in the coupler and the wave then passes into the refrigerator to pump heat. The TE uses nitrogen as its working gas and the PTR still uses helium as its working gas. With this coupler, the efficiency of the system is doubled. The engine and coupler match at a much lower operating frequency, which is of great benefit for the PTR to obtain a lower cooling temperature. The coupling place between the coupler and engine is also optimized. The onset problem is effectively solved. With these improvements, the heat-driven thermoacoustic cryocooler reaches a lowest temperature of 18.1K, which is the demonstration of heat-driven thermoacoustic refrigeration technology used for cooling at liquid hydrogen temperatures.

  12. Experimental design, operation, and results of a 4 kW high temperature steam electrolysis experiment

    Science.gov (United States)

    Zhang, Xiaoyu; O'Brien, James E.; Tao, Greg; Zhou, Can; Housley, Gregory K.

    2015-11-01

    High temperature steam electrolysis (HTSE) is a promising technology for large-scale hydrogen production. However, research on HTSE performance above the kW level is limited. This paper presents the results of 4 kW HTSE long-term test completed in a multi-kW test facility recently developed at the Idaho National Laboratory (INL). The 4 kW HTSE unit consisted of two solid oxide electrolysis stacks electrically connected in parallel, each of which included 40 electrode-supported planar cells. A current density of 0.41 A cm-2 was used for the long-term operating at a constant current mode, resulting in a theoretical hydrogen production rate about 23 slpm. A demonstration of 830 h stable operation was achieved with a degradation rate of 3.1% per 1000 h. The paper also includes detailed descriptions of the piping layout, steam generation and delivery system, test fixture, heat recuperation system, hot zone, instrumentation, and operating conditions. This successful demonstration of multi-kW scale HTSE unit will help to advance the technology toward near-term commercialization.

  13. High-temperature thermal degradation of polyethylene from reactive molecular dynamics

    Science.gov (United States)

    Lane, J. Matthew D.; Moore, Nathan W.

    Thermal degradation of polyethylene is studied under extremely high-rate temperature ramp rates from 1014 to 1010 K/s in isochoric, condensed phases. The molecular evolution and macroscopic state variables are extracted as a function of density from reactive molecular dynamics simulations using the ReaxFF potential. These results are used to parameterize a kinetic rate model for the dissociation and coalescence of hydrocarbons as a function of temperature, temperature ramp rate, and density. The results are contrasted to first-order random-scission macrokinetic models often assumed for pyrolysis of linear polyethylene under ambient conditions. Sandia National Laboratories is a multi program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04- 94AL85000.

  14. Analysis of the linearised observation operator in a soil moisture and temperature analysis scheme

    Science.gov (United States)

    Dharssi, I.; Candy, B.; Steinle, P.

    2015-06-01

    Several weather forecasting agencies have developed advanced land data assimilation systems that, in principle, can analyse any model land variable. Such systems can make use of a wide variety of observation types, such as screen level (2 m above the surface) observations and satellite based measurements of surface soil moisture and skin temperature. Indirect measurements can be used and information propagated from the surface into the deeper soil layers. A key component of the system is the calculation of the linearised observation operator matrix (Jacobian matrix) which describes the link between the observations and the land surface model variables. The elements of the Jacobian matrix (Jacobians) are estimated using finite difference by performing short model forecasts with perturbed initial conditions. The calculated Jacobians show that there can be strong coupling between the screen level and the soil. The coupling between the screen level and surface soil moisture is found to be due to a number of processes including bare soil evaporation, soil thermal conductivity as well as transpiration by plants. Therefore, there is significant coupling both during the day and at night. The coupling between the screen level and root-zone soil moisture is primarily through transpiration by plants. Therefore the coupling is only significant during the day and the vertical variation of the coupling is modulated by the vegetation root depths. The calculated Jacobians that link screen level temperature to model soil temperature are found to be largest for the topmost model soil layer and become very small for the lower soil layers. These values are largest during the night and generally positive in value. It is found that the Jacobians that link observations of surface soil moisture to model soil moisture are strongly affected by the soil hydraulic conductivity. Generally, for the Joint UK Land Environment Simulator (JULES) land surface model, the coupling between the surface

  15. AATSR - Precise Sea-Surface Temperature for Climate Monitoring and for Operational Applications

    Science.gov (United States)

    Llewellyn-Jones, David; Corlett, Gary; Donlon, Craig; Stark, John

    The Advanced Along-Track Scanning Radiometer (AATSR) is an imaging radiometer specifi- cally designed to measure Sea-Surface Temperature (SST) to the demanding levels of accuracy and stability required for climate research. AATSR, which has been operating continuously on ESA's Envisat Satellite since its launch in 2002, achieves the required levels of accuracy on account of its unique dual view, whereby each terrestrial scene is viewed twice, once at nadir and then through an inclined path which uses a different atmospheric path-length, thereby providing a direct observation of atmospheric effects, leading to an exceptionally accurate atmospheric correction. This feature is accompanied by an advanced calibration system combined with excellent optical and thermal designs. Recent rigorous and extensive comparisons with in situ data have shown that, for most of the global oceans, AATSR can achieve and accuracy of around 0.2o C with high stability, which has qualified them for use in climate analysis schemes. Because AATSR is the third sensor in a near-continuous series which started with the launch of ATSR-1 on ERS-1 satellite in 1991, there is a time-series of 16+ years of climate standard SSTs which have recently been re-processed and are now becoming available to the World-wide user community from data centres in Europe. SST data from AATSR have been included in the suite of operational SST products generated by the GODAE/GHRSST Pilot Project, on a timescale needed by operational users and in a format which allows easy ingestion and error estimates for data from AATSR and most of the other sensors currently providing SST measurements from space. Within the GODAE/GHRSST data-products, AATSR SST data are generally regarded as the benchmark for accuracy and are used to provide bias corrections for data from the other sensors, which often have superior coverage, thus exploiting synergistically the complementary qualities if the different data-sets. The UK Met Office

  16. Rheology and Gelation Temperature of Aqueous Gelatin and Sodium Alginate Solutions

    Science.gov (United States)

    Florián-Algarín, Vivian; Acevedo-Rullán, Aldo

    2008-07-01

    The rheology and gelation of biodegradable polymers, such as gelatin and sodium alginate, are of particular interest in the processing of films in pharmaceutical industry. Constant-stress temperature-ramps were used to determine the gelation temperature (Tgel). The effect of operating parameters, such as stress and cooling rate, and formulation parameters, concentration and pH among other were studied. The steady-state rheology above Tgel was experimentally determined over a wide range of concentrations and temperatures. Time-Temperature superposition and concentration shifting were used to obtain master-curves for the steady-state viscosity. Simple phenomenological models were fitted to the master curves.

  17. Designing Nanoscale Precipitates in Novel Cobalt-based Superalloys to Improve Creep Resistance and Operating Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Dunand, David C. [Northwestern Univ., Evanston, IL (United States); Seidman, David N. [Northwestern Univ., Evanston, IL (United States); Wolverton, Christopher [Northwestern Univ., Evanston, IL (United States); Saal, James E. [Northwestern Univ., Evanston, IL (United States); Bocchini, Peter J. [Northwestern Univ., Evanston, IL (United States); Sauza, Daniel J. [Northwestern Univ., Evanston, IL (United States)

    2014-10-01

    High-temperature structural alloys for aerospace and energy applications have long been dominated by Ni-base superalloys, whose strength and creep resistance can be attributed to microstructures consisting of a large volume fraction of ordered (L12) γ'-precipitates embedded in a disordered’(f.c.c.) γ-matrix. These alloys exhibit excellent mechanical behavior and thermal stability, but after decades of incremental improvement are nearing the theoretical limit of their operating temperatures. Conventional Co-base superalloys are solid-solution or carbide strengthened; although they see industrial use, these alloys are restricted to lower-stress applications because the absence of an ordered intermetallic phase places an upper limit on their mechanical performance. In 2006, a γ+γ' microstructure with ordered precipitates analogous to (L12) Ni3Al was first identified in the Co-Al-W ternary system, allowing, for the first time, the development of Co-base alloys with the potential to meet or even exceed the elevated-temperature performance of their Ni-base counterparts. The potential design space for these alloys is complex: the most advanced Ni-base superalloys may contain as many as 8-10 minor alloying additions, each with a specified purpose such as raising the γ' solvus temperature or improving creep strength. Our work has focused on assessing the effects of alloying additions on microstructure and mechanical behavior of γ'-strengthened Co-base alloys in an effort to lay the foundations for understanding this emerging alloy system. Investigation of the size, morphology, and composition of γ' and other relevant phases is investigated utilizing scanning electron microscopy (SEM) and 3-D picosecond ultraviolet local electrode atom probe tomography (APT). Microhardness, compressive yield stress at ambient and elevated temperatures, and compressive high-temperature creep measurements are employed to

  18. Reliability issues for a bolometer detector for ITER at high operating temperatures.

    Science.gov (United States)

    Meister, H; Kannamüller, M; Koll, J; Pathak, A; Penzel, F; Trautmann, T; Detemple, P; Schmitt, S; Langer, H

    2012-10-01

    The first detector prototypes for the ITER bolometer diagnostic featuring a 12.5 μm thick Pt-absorber have been realized and characterized in laboratory tests. The results show linear dependencies of the calibration parameters and are in line with measurements of prototypes with thinner absorbers. However, thermal cycling tests up to 450 °C of the prototypes with thick absorbers demonstrated that their reliability at these elevated operating temperatures is not yet sufficient. Profilometer measurements showed a deflection of the membrane hinting to stresses due to the deposition processes of the absorber. Finite element analysis (FEA) managed to reproduce the deflection and identified the highest stresses in the membrane in the region around the corners of the absorber. FEA was further used to identify changes in the geometry of the absorber with a positive impact on the intrinsic stresses of the membrane. However, further improvements are still necessary.

  19. Detailed analysis of an endoreversible fuel cell : Maximum power and optimal operating temperature determination

    CERN Document Server

    Vaudrey, A; Lanzetta, F; Glises, R

    2009-01-01

    Producing useful electrical work in consuming chemical energy, the fuel cell have to reject heat to its surrounding. However, as it occurs for any other type of engine, this thermal energy cannot be exchanged in an isothermal way in finite time through finite areas. As it was already done for various types of systems, we study the fuel cell within the finite time thermodynamics framework and define an endoreversible fuel cell. Considering different types of heat transfer laws, we obtain an optimal value of the operating temperature, corresponding to a maximum produced power. This analysis is a first step of a thermodynamical approach of design of thermal management devices, taking into account performances of the whole system.

  20. The calibration and operation of a constant-temperature crossed-wire probe in supersonic flow

    Science.gov (United States)

    Fernando, E. M.; Donovan, J. F.; Smits, A. J.

    1987-01-01

    The calibration and operation of a constant-temperature crossed-wire probe in supersonic flow is considered. Crossed-wire probes offer considerable advantages over single, inclined wires: the kinematic shear stress can be derived from a single point measurement; the rms quantities can be derived from the same measurement, and the instantaneous quantities can be obtained as a continuous function of time. However, using a crossed-wire probe in supersonic flow is subject to the following practical difficulties: the problem of flow interference, where the shock waves from one wire and its supports interfere with the flow over the other wire; the necessity for high frequency response to resolve the spectral content, and the sensitivity of the results to small changes in the calibration constants. In the present contribution, each of these problems is addressed. Practical solutions are suggested, and some encouraging results are presented.

  1. Effect of Operating Temperature on Structure Properties of TICX Nanoparticle Coating Applied by Pacvd

    Science.gov (United States)

    Shanaghi, Ali; Sabour Rouhaghdam, Ali Reza; Ahangarani, Shahrokh; Moradi, Hadi; Mohammadi, Ali

    Titanium carbide (TiC) is a widely used hard coating to improve the wear resistance and lifetime of tools because of its outstanding properties such as high melting point, high hardness, corrosion resistance and abrasion resistance. These properties were drastically improved by using nanotechnology. So in this project, TiCx was applied on hot-working die steel (H11) by Plasma CVD (PACVD). The effect of operating temperatures on TiCx structure properties have been studies by typical and advanced analyses methods such as SEM, XRD, FTIR and Raman. The best properties of TiCx nanoparticle, such as nanostructure, mechanical properties and chemical properties, were obtained at 480 °C.

  2. 46 CFR 54.25-20 - Low temperature operation-ferritic steels with properties enhanced by heat treatment (modifies...

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Low temperature operation-ferritic steels with properties enhanced by heat treatment (modifies UHT-5(c), UHT-6, UHT-23, and UHT-82). 54.25-20 Section 54.25... VESSELS Construction With Carbon, Alloy, and Heat Treated Steels § 54.25-20 Low temperature...

  3. The dew point temperature as a criterion for optimizing the operating conditions of proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Berning, Torsten

    2012-01-01

    be predicted a priori with the aid of these diagrams. Finally, guidelines for the desired cell operating temperature based on the expected dew point temperatures are developed. In the current work these guidelines are limited to the interdigitated flow field design, and they are likely to be different...

  4. Reinforcement Learning for Ramp Control: An Analysis of Learning Parameters

    Directory of Open Access Journals (Sweden)

    Chao Lu

    2016-08-01

    Full Text Available Reinforcement Learning (RL has been proposed to deal with ramp control problems under dynamic traffic conditions; however, there is a lack of sufficient research on the behaviour and impacts of different learning parameters. This paper describes a ramp control agent based on the RL mechanism and thoroughly analyzed the influence of three learning parameters; namely, learning rate, discount rate and action selection parameter on the algorithm performance. Two indices for the learning speed and convergence stability were used to measure the algorithm performance, based on which a series of simulation-based experiments were designed and conducted by using a macroscopic traffic flow model. Simulation results showed that, compared with the discount rate, the learning rate and action selection parameter made more remarkable impacts on the algorithm performance. Based on the analysis, some suggestionsabout how to select suitable parameter values that can achieve a superior performance were provided.

  5. Cumulative Interarrival Time Distributions of Freeway Entrance Ramp Traffic for Traffic Simulations

    Directory of Open Access Journals (Sweden)

    Erdinç Öner

    2013-02-01

    Full Text Available Cumulative interarrival time (IAT distributions for signalized and non-signalized freeway entrance ramps were developed to be used in digital computer traffic simulation models. The data from four different non-signalized entrance ramps (three ramps with a single lane, one ramp with two lanes and two different signalized entrance ramps (both with a single lane were used for developing the cumulative IAT distributions. The cumulative IAT distributions for the signalized and non-signalized entrance ramps were compared with each other and with the cumulative IAT distributions of the lanes for freeways. The comparative results showed that the cumulative IAT distributions for non-signalized entrance ramps are very close to the leftmost lane of a 3-lane freeway where the maximum absolute difference between the cumulative IAT distribution of the leftmost lane of a 3-lane freeway and the entrance ramps cumulative IAT distribution was 3%. The cumulative IAT distribution for the signalized entrance ramps was found to be different from the non-signalized entrance ramp cumulative IAT distribution. The approximated cumulative IAT distributions for signalized and non-signalized entrance ramp traffic for any hourly traffic volume from a few vehicles/hour up to 2,500 vehicles/hour can be obtained at http://www.ohio.edu/orite/research/uitds.cfm.

  6. Room-temperature continuous-wave operation of Ti:sapphire buried channel-waveguide lasers fabricated via proton implantation

    NARCIS (Netherlands)

    Grivas, C.; Shepherd, D.P.; Eason, R.W.; Laversenne, L.; Moretti, P.; Borca, C.N.; Pollnau, M.

    2006-01-01

    Fabrication and laser operation of proton-implanted Ti:sapphire buried channel waveguides is reported for the first time to our knowledge. Without any postimplantation annealing of the structures, continuous laser operation near 780 nm was demonstrated at room temperature at an absorbed pump power t

  7. Parametric investigation of single-expansion-ramp nozzles at Mach numbers from 0.60 to 1.20

    Science.gov (United States)

    Capone, Francis J.; Re, Richard J.; Bare, E. Ann

    1992-01-01

    An investigation was conducted in the Langley 16-Foot Transonic Tunnel to determine the effects of varying six nozzle geometric parameters on the internal and aeropropulsive performance characteristics of single-expansion-ramp nozzles. This investigation was conducted at Mach numbers from 0.60 to 1.20, nozzle pressure ratios from 1.5 to 12, and angles of attack of 0 deg +/- 6 deg. Maximum aeropropulsive performance at a particular Mach number was highly dependent on the operating nozzle pressure ratio. For example, as the nozzle upper ramp length or angle increased, some nozzles had higher performance at a Mach number of 0.90 because of the nozzle design pressure was the same as the operating pressure ratio. Thus, selection of the various nozzle geometric parameters should be based on the mission requirements of the aircraft. A combination of large upper ramp and large lower flap boattail angles produced greater nozzle drag coefficients at Mach number greater than 0.80, primarily from shock-induced separation on the lower flap of the nozzle. A static conditions, the convergent nozzle had high and nearly constant values of resultant thrust ratio over the entire range of nozzle pressure ratios tested. However, these nozzles had much lower aeropropulsive performance than the convergent-divergent nozzle at Mach number greater than 0.60.

  8. Flux consumption, current ramp-up and current diffusion in Tore Supra non-inductive Lower Hybrid scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Kazarian, F.; Litaudon, X.; Moreau, D.; Arslanbekov, R.; Hoang, G.T.; Joffrin, E.; Peysson, Y.; Allibert, J.P.; Ane, J.M.; Bremond, S. [Association Euratom-CEA, Centre d`Etudes de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee

    1995-12-31

    The main objective of the Lower Hybrid (LH) experiments performed on Tore Supra is to provide large flux savings for long pulse operation while controlling the plasma current density profile. This goal will be best achieved by applying LH wave directly during the current ramp-up phase. Experiments have been performed where a large fraction of the current is driven non-inductively during the ramp-up phase. A theoretical flux consumption scaling is presented and compared to experimental data. The time evolutions of the current density profiles are analysed with a new current diffusion code (CRONOS). In view to achieve fully non-inductive current drive discharges in a fast, systematic and reproducible way, experiments where the primary voltage is imposed have been carried out. In a complementary approach, an appropriate transformer flux feedback scheme has been also studied. (author) 6 refs.; 6 figs.

  9. Radar echo processing with partitioned de-ramp

    Science.gov (United States)

    Dubbert, Dale F.; Tise, Bertice L.

    2013-03-19

    The spurious-free dynamic range of a wideband radar system is increased by apportioning de-ramp processing across analog and digital processing domains. A chirp rate offset is applied between the received waveform and the reference waveform that is used for downconversion to the intermediate frequency (IF) range. The chirp rate offset results in a residual chirp in the IF signal prior to digitization. After digitization, the residual IF chirp is removed with digital signal processing.

  10. Adiabaticity of the ramping process of an ac dipole

    Directory of Open Access Journals (Sweden)

    R. Tomás

    2005-02-01

    Full Text Available ac dipoles in accelerators are used to excite coherent betatron oscillations at a drive frequency close to the tune. If the excitation amplitude is slowly increased to the desired value and slowly decreased back to zero there is no significant emittance growth. The aim of this article is to study the adiabaticity of the ramping process of an ac dipole as a function of the different parameters involved.

  11. Preliminary operational results of the low-temperature solar industrial process heat field tests

    Energy Technology Data Exchange (ETDEWEB)

    Kutscher, C.F.; Davenport, R.L.

    1980-06-01

    Six solar industrial process heat field tests have been in operation for a year or more - three are hot water systems and three are hot air systems. All are low-temperature projects (process heat at temperatures below 212/sup 0/F). Performance results gathered by each contractor's data acquisition system are presented and project costs and problems encountered are summarized. Flat-plate, evacuated-tube, and line-focus collectors are all represented in the program, with collector array areas ranging from 2500 to 21,000 ft/sup 2/. Collector array efficiencies ranged from 12% to 36% with net system efficiencies from 8% to 33%. Low efficiencies are attributable in some cases to high thermal losses and, for the two projects using air collectors, are due in part to high parasitic power consumption. Problems have included industrial effluents on collectors, glazing and absorber surface failures, excessive thermal losses, freezing and overheating, control problems, and data acquisition system failure. With design and data acquisition costs excluded costs of the projects ranged from $25/ft/sup 2/ to $87/ft/sup 2/ and $499/(MBtu/yr) to $1537/(MBtu/yr).

  12. Temperature stable operation of YCOB crystal for giant-pulse green microlaser.

    Science.gov (United States)

    Kausas, Arvydas; Loiseau, Pascal; Aka, Gerard; Zheng, Yanqing; Zheng, Lihe; Taira, Takunori

    2017-03-20

    In this work the performance of two yttrium calcium oxyborate (YCOB) crystals made by Czochralski and Bridgman growth process was measured. By using high peak power, passively Q-switched Nd3+:YAG/Cr4+:YAG microlaser, high conversion second harmonic generation efficiency were obtained. Laser pulses at 532 nm with 1.14 mJ energy and 223 ps duration were obtained with a 15-mm long YCOB crystal that was grown by Bridgman method. The conversion efficiency was 70.2%, comparable with the conversion efficiency of 72.8% that was achieved with 10-mm long lithium triborate (LBO) nonlinear crystal. Also, for the first time, experimental data on temperature tuning in type I YCOB crystal was measured with linear slope in 200°C temperature range equal to -0.057%/°C and -0.064%/°C for the Czochralski and Bridgman grown crystals, respectively. Such YCOB nonlinear crystal can become a serious option for developing laser sources with high-peak power at high repetition rate that can operate in harsh environment.

  13. InSb Mid-Infrared Photon Detector for Room-Temperature Operation

    Science.gov (United States)

    Ueno, Koichiro; Gomes Camargo, Edson; Katsumata, Takashi; Goto, Hiromasa; Kuze, Naohiro; Kangawa, Yoshihiro; Kakimoto, Koichi

    2013-09-01

    We developed a small InSb mid-infrared (2-7 µm wavelength range) photon detector that operates at room temperature. The photodiode was made from (hetero epitaxial) InSb layers that were grown on a semi-insulating GaAs substrate by molecular beam epitaxy. To suppress the effects of the diffusion current of the p-i-n photodiode, we used an AlInSb barrier layer that raises the resistance of the photodiode. We also optimized the device's doping concentration and the infrared incidence window structure. These optimization steps realized high photoelectric current output in a room-temperature environment. We also increased the signal-to-noise ratio of the detector by connecting multiple photodiodes in series. The size of this detector is 1.9×2.7×0.4 mm3 and the detectivity is 2.8×108 cm Hz1/2/W at 300 K. This is a practical IR detector that can be used in general signal amplification ICs.

  14. Feasibility study of SiGHT: a novel ultra low background photosensor for low temperature operation

    Science.gov (United States)

    Wang, Y.; Fan, A.; Fiorillo, G.; Galbiati, C.; Guan, M. Y.; Korga, G.; Pantic, E.; Razeto, A.; Renshaw, A.; Rossi, B.; Suvorov, Y.; Wang, H.; Yang, C. G.

    2017-02-01

    Rare event search experiments, such as those searching for dark matter and observations of neutrinoless double beta decay, require ultra low levels of radioactive background for unmistakable identification. In order to reduce the radioactive background of detectors used in these types of event searches, low background photosensors are required, as the physical size of these detectors become increasing larger, and hence the number of such photosensors used also increases rapidly. Considering that most dark matter and neutrinoless double beta decay experiments are turning towards using noble liquids as the target choice, liquid xenon and liquid argon for instance, photosensors that can work well at cryogenic temperatures are required, 165 K and 87 K for liquid xenon and liquid argon, respectively. The Silicon Geiger Hybrid Tube (SiGHT) is a novel photosensor designed specifically for use in ultra low background experiments operating at cryogenic temperatures. It is based on the proven photocathode plus silicon photomultiplier (SiPM) hybrid technology and consists of very few other, but also ultra radio-pure, materials like fused silica and silicon for the SiPM. The introduction of the SiGHT concept, as well as a feasibility study for its production, is reported in this paper.

  15. Evaluation of Land Surface Temperature Operationally Retrieved from Korean Geostationary Satellite (COMS Data

    Directory of Open Access Journals (Sweden)

    A-Ra Cho

    2013-08-01

    Full Text Available We evaluated the precision of land surface temperature (LST operationally retrieved from the Korean multipurpose geostationary satellite, Communication, Ocean and Meteorological Satellite (COMS. The split-window (SW-type retrieval algorithm was developed through radiative transfer model simulations under various atmospheric profiles, satellite zenith angles, surface emissivity values and surface lapse rate conditions using Moderate Resolution Atmospheric Transmission version 4 (MODTRAN4. The estimation capabilities of the COMS SW (CSW LST algorithm were evaluated for various impacting factors, and the retrieval accuracy of COMS LST data was evaluated with collocated Moderate Resolution Imaging Spectroradiometer (MODIS LST data. The surface emissivity values for two SW channels were generated using a vegetation cover method. The CSW algorithm estimated the LST distribution reasonably well (averaged bias = 0.00 K, Root Mean Square Error (RMSE = 1.41 K, correlation coefficient = 0.99; however, the estimation capabilities of the CSW algorithm were significantly impacted by large brightness temperature differences and surface lapse rates. The CSW algorithm reproduced spatiotemporal variations of LST comparing well to MODIS LST data, irrespective of what month or time of day the data were collected from. The one-year evaluation results with MODIS LST data showed that the annual mean bias, RMSE and correlation coefficient for the CSW algorithm were −1.009 K, 2.613 K and 0.988, respectively.

  16. Integrated Operating Scenario to Achieve 100-Second, High Electron Temperature Discharge on EAST

    Science.gov (United States)

    Qian, Jinping; Gong, Xianzu; Wan, Baonian; Liu, Fukun; Wang, Mao; Xu, Handong; Hu, Chundong; Wang, Liang; Li, Erzhong; Zeng, Long; Ti, Ang; Shen, Biao; Lin, Shiyao; Shao, Linming; Zang, Qing; Liu, Haiqing; Zhang, Bin; Sun, Youwen; Xu, Guosheng; Liang, Yunfeng; Xiao, Bingjia; Hu, Liqun; Li, Jiangang; EAST Team

    2016-05-01

    Stationary long pulse plasma of high electron temperature was produced on EAST for the first time through an integrated control of plasma shape, divertor heat flux, particle exhaust, wall conditioning, impurity management, and the coupling of multiple heating and current drive power. A discharge with a lower single null divertor configuration was maintained for 103 s at a plasma current of 0.4 MA, q95 ≈7.0, a peak electron temperature of >4.5 keV, and a central density ne(0)˜2.5×1019 m-3. The plasma current was nearly non-inductive (Vloop heating at 140 GHz, and 0.4 MW modulated neutral deuterium beam injected at 60 kV. This progress demonstrated strong synergy of electron cyclotron and lower hybrid electron heating, current drive, and energy confinement of stationary plasma on EAST. It further introduced an example of integrated “hybrid” operating scenario of interest to ITER and CFETR. supported by the National Magnetic Confinement Fusion Science Foundation of China (Nos. 2015GB102000 and 2014GB103000)

  17. Fabrication of room temperature continuous-wave operation GaN-based ultraviolet laser diodes

    Science.gov (United States)

    Zhao, Degang; Yang, Jing; Liu, Zongshun; Chen, Ping; Zhu, Jianjun; Jiang, Desheng; Shi, Yongsheng; Wang, Hai; Duan, Lihong; Zhang, Liqun; Yang, Hui

    2017-06-01

    Two kinds of continuous-wave GaN-based ultraviolet laser diodes (LDs) operated at room temperature and with different emission wavelengths are demonstrated. The LDs epitaxial layers are grown on GaN substrate by metalorganic chemical vapor deposition, with a 10 × 600 μm2 ridge waveguide structure. The electrical and optical characteristics of the ultraviolet LDs are investigated under direct-current injection at room temperature. The stimulated emission peak wavelength of first LD is 392.9 nm, the threshold current density and voltage is 1.5 kA/cm2 and 5.0 V, respectively. The output light power is 80 mW under the 4.0 kA/cm2 injection current density. The stimulated emission peak wavelength of second LD is 381.9 nm, the threshold current density the voltage is 2.8 kA/cm2 and 5.5 V, respectively. The output light power is 14 mW under a 4.0 kA/cm2 injection current density. Projects the supported by the National Key R&D Program of China (Nos. 2016YFB0401801, 2016YFB0400803), the National Natural Science Foundation of China (Nos. 61674138, 61674139, 61604145, 61574135, 61574134, 61474142, 61474110, 61377020, 61376089), the Science Challenge Project (No. JCKY2016212A503), and the One Hundred Person Project of the Chinese Academy of Sciences.

  18. Computer-Aided Design of Materials for use under High Temperature Operating Condition

    Energy Technology Data Exchange (ETDEWEB)

    Rajagopal, K. R.; Rao, I. J.

    2010-01-31

    The procedures in place for producing materials in order to optimize their performance with respect to creep characteristics, oxidation resistance, elevation of melting point, thermal and electrical conductivity and other thermal and electrical properties are essentially trial and error experimentation that tend to be tremendously time consuming and expensive. A computational approach has been developed that can replace the trial and error procedures in order that one can efficiently design and engineer materials based on the application in question can lead to enhanced performance of the material, significant decrease in costs and cut down the time necessary to produce such materials. The work has relevance to the design and manufacture of turbine blades operating at high operating temperature, development of armor and missiles heads; corrosion resistant tanks and containers, better conductors of electricity, and the numerous other applications that are envisaged for specially structured nanocrystalline solids. A robust thermodynamic framework is developed within which the computational approach is developed. The procedure takes into account microstructural features such as the dislocation density, lattice mismatch, stacking faults, volume fractions of inclusions, interfacial area, etc. A robust model for single crystal superalloys that takes into account the microstructure of the alloy within the context of a continuum model is developed. Having developed the model, we then implement in a computational scheme using the software ABAQUS/STANDARD. The results of the simulation are compared against experimental data in realistic geometries.

  19. Diagnostics comparing sea surface temperature feedbacks from operational hurricane forecasts to observations

    Directory of Open Access Journals (Sweden)

    Ian D. Lloyd

    2011-11-01

    Full Text Available This paper examines the ability of recent versions of the Geophysical Fluid Dynamics Laboratory Operational Hurricane Forecast Model (GHM to reproduce the observed relationship between hurricane intensity and hurricane-induced Sea Surface Temperature (SST cooling. The analysis was performed by taking a Lagrangian composite of all hurricanes in the North Atlantic from 1998–2009 in observations and 2005–2009 for the GHM. A marked improvement in the intensity-SST relationship for the GHM compared to observations was found between the years 2005 and 2006–2009 due to the introduction of warm-core eddies, a representation of the loop current, and changes to the drag coefficient parameterization for bulk turbulent flux computation. A Conceptual Hurricane Intensity Model illustrates the essential steady-state characteristics of the intensity-SST relationship and is explained by two coupled equations for the atmosphere and ocean. The conceptual model qualitatively matches observations and the 2006–2009 period in the GHM, and presents supporting evidence for the conclusion that weaker upper oceanic thermal stratification in the Gulf of Mexico, caused by the introduction of the loop current and warm core eddies, is crucial to explaining the observed SST-intensity pattern. The diagnostics proposed by the conceptual model offer an independent set of metrics for comparing operational hurricane forecast models to observations.

  20. Effects of temperature on flood forecasting: analysis of an operative case study in Alpine basins

    Directory of Open Access Journals (Sweden)

    A. Ceppi

    2013-04-01

    Full Text Available In recent years the interest in the forecast and prevention of natural hazards related to hydro-meteorological events has increased the challenge for numerical weather modelling, in particular for limited area models, to improve the quantitative precipitation forecasts (QPF for hydrological purposes. After the encouraging results obtained in the MAP D-PHASE Project, we decided to devote further analyses to show recent improvements in the operational use of hydro-meteorological chains, and above all to better investigate the key role played by temperature during snowy precipitation. In this study we present a reanalysis simulation of one meteorological event, which occurred in November 2008 in the Piedmont Region. The attention is focused on the key role of air temperature, which is a crucial feature in determining the partitioning of precipitation in solid and liquid phase, influencing the quantitative discharge forecast (QDF into the Alpine region. This is linked to the basin ipsographic curve and therefore by the total contributing area related to the snow line of the event. In order to assess hydrological predictions affected by meteorological forcing, a sensitivity analysis of the model output was carried out to evaluate different simulation scenarios, considering the forecast effects which can radically modify the discharge forecast. Results show how in real-time systems hydrological forecasters have to consider also the temperature uncertainty in forecasts in order to better understand the snow dynamics and its effect on runoff during a meteorological warning with a crucial snow line over the basin. The hydrological ensemble forecasts are based on the 16 members of the meteorological ensemble system COSMO-LEPS (developed by ARPA-SIMC based on the non-hydrostatic model COSMO, while the hydrological model used to generate the runoff simulations is the rainfall–runoff distributed FEST-WB model, developed at Politecnico di Milano.

  1. Kinematics investigations of cylinders rolling down a ramp using tracker

    Science.gov (United States)

    Prima, Eka Cahya; Mawaddah, Menurseto; Winarno, Nanang; Sriwulan, Wiwin

    2016-02-01

    Nowadays, students' exploration as well as students' interaction in the application stage of learning cycle can be improved by directly model real-world objects based on Newton's Law using Open Source Physics (OSP) computer-modeling tools. In a case of studying an object rolling down a ramp, a traditional experiment method commonly uses a ticker tape sliding through a ticker timer. However, some kinematics parameters such as the instantaneous acceleration and the instantaneous speed of object cannot be investigated directly. By using the Tracker video analysis method, all kinematics parameters of cylinders rolling down a ramp can be investigated by direct visual inspection. The result shows that (1) there are no relations of cylinders' mass as well as cylinders' radius towards their kinetics parameters. (2) Excluding acceleration data, the speed and position as function of time follow the theory. (3) The acceleration data are in the random order, but their trend-lines closely fit the theory with 0.15% error. (4) The decrease of acceleration implicitly occurs due to the air friction acting on the cylinder during rolling down. (5) The cylinder's inertial moment constant has been obtained experimentally with 3.00% error. (6) The ramp angle linearly influences the cylinders' acceleration with 2.36% error. This research implied that the program can be further applied to physics educational purposes.

  2. Non-inductive Plasma Start-up and Current Ramp-up in NSTX-U

    Science.gov (United States)

    Raman, R.; Jarboe, T. R.; Jardin, S. C.; Kessel, C. E.; Mueller, D.; Nelson, B. A.; Poli, F.; Taylor, G.; NSTX Research Team; Princeton Plasma Physics Laboratory Team

    2013-10-01

    Results from NSTX Transient Coaxial Helicity Injection (CHI) experiments have demonstrated generation of 300 kA start-up currents, and when these discharges were coupled to induction they attained 1 MA of plasma current consuming 65% of the inductive flux of standard inductive-only discharges in NSTX. The NSTX-U device, which is now under construction at PPPL, will have numerous improvements to enhance transient CHI start-up. These are: (1) factor of two increase in toroidal field, (2) more than 2.5 times the injector flux, (3) increased CHI voltage, (4) full lithium coverage to reduce low-Z impurities and (5) 1 MW ECH system for increasing the electron temperature of CHI discharges to allow direct coupling to NBI current drive using a new second more tangential neutral beam system. In support of NSTX-U objectives for full non-inductive start-up and current ramp-up, the TSC code has been used for a full discharge simulation in which a transient CHI discharge is used as the front end of the non-inductive current ramp-up simulation. This work supported by U.S. DOE Contracts DE-AC02-09CH11466 and DE-FG02-99ER54519 AM08.

  3. Effect of dilute tungsten alloying on the dynamic strength of tantalum under ramp compression

    Science.gov (United States)

    Alexander, C. S.; Brown, J. L.; Millett, J. C. F.; Whiteman, G.; Asay, J. R.; Bourne, N. K.

    2015-06-01

    The strength of tantalum and tantalum alloys are of considerable interest due to their widespread use in both military and industrial applications. Previous work has shown that strength in these materials is tied to dislocation density and mobility within the microstructure. Accordingly, strength has been observed to increase with dilute alloying which serves to increase the dislocation density. In this study, we examine the effect of alloying on the strength of a dilute tantalum-tungsten alloy (2.5 weight percent W) under ramp compression. The strength of the alloy is measured using the ``self-consistent'' technique which examines the response under longitudinal unloading from peak compression. The results are compared to previous studies of pure tantalum and dilute tantalum-tungsten alloys under both shock and ramp compression and indicate strengthening of the alloy when compared to pure tantalum. Sandia National Labs is a multi-program laboratory managed and operated by Sandia Corp., a wholly owned subsidiary of Lockheed Martin Corp., for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  4. Thermodynamic Properties of Fast Ramped Superconducting Accelerator Magnets for the Fair Project

    Science.gov (United States)

    Fischer, E.; Mierau, A.; Schnizer, P.; Bleile, A.; Gärtner, W.; Guymenuk, O.; Khodzhibagiyan, H.; Schroeder, C.; Sikler, G.; Stafiniak, A.

    2010-04-01

    The 100 Tm synchrotron SIS 100 is the core component of the international Facility of Antiproton and Ion Research (FAIR) to be built at GSI Darmstadt. The 108 bending magnets are 3 m long 2 T superferric dipoles providing a nominal ramp rate of 4 T/s within a usable aperture of 115 mmṡ60 mm. An intensive R&D period was conducted to minimise the AC losses to lower operation costs and to guarantee a safe thermal stability for long term continuous cycling with a maximum repetition frequency of 1 Hz. The latter requirement is strictly limited by the overall heat flow originated by eddy currents and hysteresis losses in iron yoke and coil as well as by its hydraulic resistance respective to the forced two phase helium cooling flow within the hollow superconducting cable. Recently three full size dipoles—and one quadrupole magnets were built and intensive tests have been started in the end of 2008 at the GSI cryogenic test facility. We present the measured thermodynamic parameters of the first tested dipole: AC losses depending on Bmax and dB/dt for various characteristic ramping modes and conclude for necessary optimisations toward the final design of the series magnets.

  5. Analysis of the Impact of Decreasing District Heating Supply Temperature on Combined Heat and Power Plant Operation

    Directory of Open Access Journals (Sweden)

    Bolonina Alona

    2014-12-01

    Full Text Available District heating systems are widely used to supply heat to different groups of heat consumers. The district heating system offers great opportunities for combined heat and power production. In this paper decreasing district heating supply temperature is analysed in the context of combined heat and power plant operation. A mathematical model of a CHP plant is developed using both empirical and theoretical equations. The model is used for analysis of modified CHP plant operation modes with reduced district heating supply temperature. Conclusions on the benefits of new operation modes are introduced.

  6. Effects of Operating Temperature on Droplet Casting of Flexible Polymer/Multi-Walled Carbon Nanotube Composite Gas Sensors

    Science.gov (United States)

    Chiou, Jin-Chern; Wu, Chin-Cheng; Huang, Yu-Chieh; Chang, Shih-Cheng; Lin, Tse-Mei

    2016-01-01

    This study examined the performance of a flexible polymer/multi-walled carbon nanotube (MWCNT) composite sensor array as a function of operating temperature. The response magnitudes of a cost-effective flexible gas sensor array equipped with a heater were measured with respect to five different operating temperatures (room temperature, 40 °C, 50 °C, 60 °C, and 70 °C) via impedance spectrum measurement and sensing response experiments. The selected polymers that were droplet cast to coat a MWCNT conductive layer to form two-layer polymer/MWCNT composite sensing films included ethyl cellulose (EC), polyethylene oxide (PEO), and polyvinylpyrrolidone (PVP). Electrical characterization of impedance, sensing response magnitude, and scanning electron microscope (SEM) morphology of each type of polymer/MWCNT composite film was performed at different operating temperatures. With respect to ethanol, the response magnitude of the sensor decreased with increasing operating temperatures. The results indicated that the higher operating temperature could reduce the response and influence the sensitivity of the polymer/MWCNT gas sensor array. The morphology of polymer/MWCNT composite films revealed that there were changes in the porous film after volatile organic compound (VOC) testing. PMID:28025507

  7. Effects of Operating Temperature on Droplet Casting of Flexible Polymer/Multi-Walled Carbon Nanotube Composite Gas Sensors

    Directory of Open Access Journals (Sweden)

    Jin-Chern Chiou

    2016-12-01

    Full Text Available This study examined the performance of a flexible polymer/multi-walled carbon nanotube (MWCNT composite sensor array as a function of operating temperature. The response magnitudes of a cost-effective flexible gas sensor array equipped with a heater were measured with respect to five different operating temperatures (room temperature, 40 °C, 50 °C, 60 °C, and 70 °C via impedance spectrum measurement and sensing response experiments. The selected polymers that were droplet cast to coat a MWCNT conductive layer to form two-layer polymer/MWCNT composite sensing films included ethyl cellulose (EC, polyethylene oxide (PEO, and polyvinylpyrrolidone (PVP. Electrical characterization of impedance, sensing response magnitude, and scanning electron microscope (SEM morphology of each type of polymer/MWCNT composite film was performed at different operating temperatures. With respect to ethanol, the response magnitude of the sensor decreased with increasing operating temperatures. The results indicated that the higher operating temperature could reduce the response and influence the sensitivity of the polymer/MWCNT gas sensor array. The morphology of polymer/MWCNT composite films revealed that there were changes in the porous film after volatile organic compound (VOC testing.

  8. Generation of high resolution sea surface temperature using multi-satellite data for operational oceanography

    Institute of Scientific and Technical Information of China (English)

    YANG Chan-Su; KIM Sun-Hwa; OUCHI Kazuo; BACK Ji-Hun

    2015-01-01

    In the present article, we introduce a high resolution sea surface temperature (SST) product generated daily by Korea Institute of Ocean Science and Technology (KIOST). The SST product is comprised of four sets of data including eight-hour and daily average SST data of 1 km resolution, and is based on the four infrared (IR) satellite SST data acquired by advanced very high resolution radiometer (AVHRR), Moderate Resolution Imaging Spectroradiometer (MODIS), Multifunctional Transport Satellites-2 (MTSAT-2) Imager and Meteorological Imager (MI), two microwave radiometer SSTs acquired by Advanced Microwave Scanning Radiometer 2 (AMSR2), and WindSAT within-situ temperature data. These input satellite andin-situ SST data are merged by using the optimal interpolation (OI) algorithm. The root-mean-square-errors (RMSEs) of satellite andin-situ data are used as a weighting value in the OI algorithm. As a pilot product, four SST data sets were generated daily from January to December 2013. In the comparison between the SSTs measured by moored buoys and the daily mean KIOST SSTs, the estimated RMSE was 0.71°C and the bias value was –0.08°C. The largest RMSE and bias were 0.86 and –0.26°C respectively, observed at a buoy site in the boundary region of warm and cold waters with increased physical variability in the Sea of Japan/East Sea. Other site near the coasts shows a lower RMSE value of 0.60°C than those at the open waters. To investigate the spatial distributions of SST, the Group for High Resolution Sea Surface Temperature (GHRSST) product was used in the comparison of temperature gradients, and it was shown that the KIOST SST product represents well the water mass structures around the Korean Peninsula. The KIOST SST product generated from both satellite and buoy data is expected to make substantial contribution to the Korea Operational Oceanographic System (KOOS) as an input parameter for data assimilation.

  9. Derivation and evaluation of land surface temperature from the geostationary operational environmental satellite series

    Science.gov (United States)

    Fang, Li

    The Geostationary Operational Environmental Satellites (GOES) have been continuously monitoring the earth surface since 1970, providing valuable and intensive data from a very broad range of wavelengths, day and night. The National Oceanic and Atmospheric Administration's (NOAA's) National Environmental Satellite, Data, and Information Service (NESDIS) is currently operating GOES-15 and GOES-13. The design of the GOES series is now heading to the 4 th generation. GOES-R, as a representative of the new generation of the GOES series, is scheduled to be launched in 2015 with higher spatial and temporal resolution images and full-time soundings. These frequent observations provided by GOES Image make them attractive for deriving information on the diurnal land surface temperature (LST) cycle and diurnal temperature range (DTR). These parameters are of great value for research on the Earth's diurnal variability and climate change. Accurate derivation of satellite-based LSTs from thermal infrared data has long been an interesting and challenging research area. To better support the research on climate change, the generation of consistent GOES LST products for both GOES-East and GOES-West from operational dataset as well as historical archive is in great demand. The derivation of GOES LST products and the evaluation of proposed retrieval methods are two major objectives of this study. Literature relevant to satellite-based LST retrieval techniques was reviewed. Specifically, the evolution of two LST algorithm families and LST retrieval methods for geostationary satellites were summarized in this dissertation. Literature relevant to the evaluation of satellite-based LSTs was also reviewed. All the existing methods are a valuable reference to develop the GOES LST product. The primary objective of this dissertation is the development of models for deriving consistent GOES LSTs with high spatial and high temporal coverage. Proper LST retrieval algorithms were studied

  10. Effects of Operating Temperatures and Accelerated Environmental Ageing on the Mechanical Properties of a Glass-Vinylester Composite

    Science.gov (United States)

    Klasztorny, M.; Nycz, D. B.; Romanowski, R. K.; Gotowicki, P.; Kiczko, A.; Rudnik, D.

    2017-07-01

    Experimental identification of the mechanical properties of a selected glass-vinylester structural composite is developed, performed, and analysed taking into account accelerated environmental ageing and three operating temperatures (-20, 20, and 55°C) corresponding to the operating temperature range for composite footbridges in the Central Europe. The main constituents of the composite fabricated using infusion technology are a bidirectional balanced stitched E-glass fabric and a flame retardant, vinylester resin. After homogenization, the composite reinforced with one fabric forms a single lamina and is modeled as a linear elastic-brittle orthotropic material. Full sets of material constants were identified for the initial and aged composites at the selected operating temperatures. The accelerated environmental ageing of the composite was performed on 4-layer symmetric laminate platelets protected with a 300-mm-thick gelcoat layer, using an ageing chamber and a relevant ageing programme. A comparative analysis was carried out in order to determine the effects of operating temperature and accelerated environmental ageing on the material constants of the GFRP composite. It is found that the composite tested can be modeled as a linear elastic-brittle orthotropic material to the level of 20% of its strength in each strength test. The impact of the accelerated environmental ageing and operating temperature in the range from -20 to 55°C on the elastic/strength/ultimate strain constants of the selected E-glass/vinylester composite can be significant and different for individual constants.

  11. Analysis of stationary fuel cell dynamic ramping capabilities and ultra capacitor energy storage using high resolution demand data

    Science.gov (United States)

    Meacham, James R.; Jabbari, Faryar; Brouwer, Jacob; Mauzey, Josh L.; Samuelsen, G. Scott

    Current high temperature fuel cell (HTFC) systems used for stationary power applications (in the 200-300 kW size range) have very limited dynamic load following capability or are simply base load devices. Considering the economics of existing electric utility rate structures, there is little incentive to increase HTFC ramping capability beyond 1 kWs -1 (0.4% s -1). However, in order to ease concerns about grid instabilities from utility companies and increase market adoption, HTFC systems will have to increase their ramping abilities, and will likely have to incorporate electrical energy storage (EES). Because batteries have low power densities and limited lifetimes in highly cyclic applications, ultra capacitors may be the EES medium of choice. The current analyses show that, because ultra capacitors have a very low energy storage density, their integration with HTFC systems may not be feasible unless the fuel cell has a ramp rate approaching 10 kWs -1 (4% s -1) when using a worst-case design analysis. This requirement for fast dynamic load response characteristics can be reduced to 1 kWs -1 by utilizing high resolution demand data to properly size ultra capacitor systems and through demand management techniques that reduce load volatility.

  12. Mechanically induced silyl ester cleavage under acidic conditions investigated by AFM-based single-molecule force spectroscopy in the force-ramp mode.

    Science.gov (United States)

    Schmidt, Sebastian W; Pill, Michael F; Kersch, Alfred; Clausen-Schaumann, Hauke; Beyer, Martin K

    2014-01-01

    AFM-based dynamic single-molecule force spectroscopy was used to stretch carboxymethylated amylose (CMA) polymers, which have been covalently tethered between a silanized glass substrate and a silanized AFM tip via acid-catalyzed ester condensation at pH 2.0. Rupture forces were measured as a function of temperature and force loading rate in the force-ramp mode. The data exhibit significant statistical scattering, which is fitted with a maximum likelihood estimation (MLE) algorithm. Bond rupture is described with a Morse potential based Arrhenius kinetics model. The fit yields a bond dissociation energy De = 35 kJ mol(-1) and an Arrhenius pre-factor A = 6.6 × 10(4) s(-1). The bond dissociation energy is consistent with previous experiments under identical conditions, where the force-clamp mode was employed. However, the bi-exponential decay kinetics, which the force-clamp results unambiguously revealed, are not evident in the force-ramp data. While it is possible to fit the force-ramp data with a bi-exponential model, the fit parameters differ from the force-clamp experiments. Overall, single-molecule force spectroscopy in the force-ramp mode yields data whose information content is more limited than force-clamp data. It may, however, still be necessary and advantageous to perform force-ramp experiments. The number of successful events is often higher in the force-ramp mode, and competing reaction pathways may make force-clamp experiments impossible.

  13. Photodetector development at Fraunhofer IAF: From LWIR to SWIR operating from cryogenic close to room temperature

    Science.gov (United States)

    Daumer, V.; Gramich, V.; Müller, R.; Schmidt, J.; Rutz, F.; Stadelmann, T.; Wörl, A.; Rehm, R.

    2017-02-01

    Photodetectors in the non-visible region of the electromagnetic spectrum are essential for security, defense and space science as well as industrial and scientific applications. The research activities at Fraunhofer IAF cover a broad range in the infrared (IR) regime. Whereas short-wavelength IR (SWIR, <1.7 μm) detectors are realized by InGaAs/InP structures, InAs/GaSb type-II superlattice (T2SL) infrared detectors are developed for the spectral bands from mid- (MWIR, 3-5 μm) to long-wavelength IR (LWIR, 8-12 μm). We report on the extension of the superlattice empirical pseudopotential method (SEPM) to 300 K for the design of LWIR heterostructures for operation near room temperature. Recently, we have also adapted heterostructure concepts to our well established bi-spectral T2SL MWIR detector resulting in a dark current density below 2 × 10-9 A/cm2 for a cut-off wavelength close to 5 μm. Finally, we present first results obtained with a gated viewing system based on our InGaAs/InAlAs/InP avalanche photodiode arrays.

  14. Variation of ADM1 by using temperature-phased anaerobic digestion (TPAD) operation.

    Science.gov (United States)

    Lee, Myung-Yeol; Suh, Chang-Won; Ahn, Yong-Tae; Shin, Hang-Sik

    2009-06-01

    The objective of the study was to examine the application of the Anaerobic Digestion Model No. 1 (ADM1) developed by the IWA task group for mathematical modelling of anaerobic process. Lab-scale temperature-phased anaerobic digestion (TPAD) process were operated continuously, and were fed with co-substrate composed of dog food and flour. The model platform implemented in the simulation was a derivative of the ADM1. Sensitivity analysis showed that k(m.process) (maximum specific uptake rate) and K(S.process) (half saturation value) had high sensitivities to model components. Important parameters including maximum uptake rate for propionate utilisers (k(m.pro)) and half saturation constant for acetate utilisers (K(S.ac)) in the thermophilic digester and maximum uptake rate for acetate utilisers (k(m.ac)) in the mesophilic digester were estimated using iterative methods, which optimized the parameters with experimental results. Simulation with estimated parameters showed good agreement with experimental results in the case of methane production, uptake of acetate, soluble chemical oxygen demand (SCOD) and total chemical oxygen demand (TCOD). Under these conditions, the model predicted reasonably well the dynamic behavior of the TPAD process for verifying the model.

  15. Simulation Study of Effects, Operating Temperature and Layer Thickness on Thin Film CIGS Solar Cell Performance

    Directory of Open Access Journals (Sweden)

    A.D. Pogrebnjak

    2011-01-01

    Full Text Available SCAPS- program is designed basically for the simulation and studying the properties of photonic devices. We explored the important controllable design parameters affecting the performance of the hetero junction solar cells, as operating temperature that we noticed increasing in J-V characteristics by increasing T, the effect of thickness of each layer on the performance of the cell was studied, an increasing of J-V characteristics with increasing p-layer , In the numerical example, 3 μm absorber layer and CdS layer 0.05 μm, ZnO layer 0.1 μm, works the best for given doping density, if we change the optimum value , the efficiency can reach to 17.72 % with FF 83.88 %, Voc = 0.725 Volt, Jsc = 29.07 mA/cm2 at 300 K, in this case, we have come out the optimum parameters to achieve the best performance of this type of cell, and then to made comparison with practical CIGS cell.

  16. High Operating Temperature Midwave Quantum Dot Barrier Infrared Detector (QD-BIRD)

    Science.gov (United States)

    Ting, David Z.; Soibel, Alexander; Hill, Cory J.; Keo, Sam A.; Mumolo, Jason M.; Gunapala, Sarath D.

    2012-01-01

    The nBn or XBn barrier infrared detector has the advantage of reduced dark current resulting from suppressed Shockley-Read-Hall (SRH) recombination and surface leakage. High performance detectors and focal plane arrays (FPAs) based on InAsSb absorber lattice matched to GaSb substrate, with a matching AlAsSb unipolar electron barrier, have been demonstrated. The band gap of lattice-matched InAsSb yields a detector cutoff wavelength of approximately 4.2 ??m when operating at 150K. We report results on extending the cutoff wavelength of midwave barrier infrared detectors by incorporating self-assembled InSb quantum dots into the active area of the detector. Using this approach, we were able to extend the detector cutoff wavelength to 6 ?m, allowing the coverage of the full midwave infrared (MWIR) transmission window. The quantum dot barrier infrared detector (QD-BIRD) shows infrared response at temperatures up to 225 K.

  17. High Operating Temperature Midwave Quantum Dot Barrier Infrared Detector (QD-BIRD)

    Science.gov (United States)

    Ting, David Z.; Soibel, Alexander; Hill, Cory J.; Keo, Sam A.; Mumolo, Jason M.; Gunapala, Sarath D.

    2012-01-01

    The nBn or XBn barrier infrared detector has the advantage of reduced dark current resulting from suppressed Shockley-Read-Hall (SRH) recombination and surface leakage. High performance detectors and focal plane arrays (FPAs) based on InAsSb absorber lattice matched to GaSb substrate, with a matching AlAsSb unipolar electron barrier, have been demonstrated. The band gap of lattice-matched InAsSb yields a detector cutoff wavelength of approximately 4.2 ??m when operating at 150K. We report results on extending the cutoff wavelength of midwave barrier infrared detectors by incorporating self-assembled InSb quantum dots into the active area of the detector. Using this approach, we were able to extend the detector cutoff wavelength to 6 ?m, allowing the coverage of the full midwave infrared (MWIR) transmission window. The quantum dot barrier infrared detector (QD-BIRD) shows infrared response at temperatures up to 225 K.

  18. Single-ion polymer electrolyte membranes enable lithium-ion batteries with a broad operating temperature range.

    Science.gov (United States)

    Cai, Weiwei; Zhang, Yunfeng; Li, Jing; Sun, Yubao; Cheng, Hansong

    2014-04-01

    Conductive processes involving lithium ions are analyzed in detail from a mechanistic perspective, and demonstrate that single ion polymeric electrolyte (SIPE) membranes can be used in lithium-ion batteries with a wide operating temperature range (25-80 °C) through systematic optimization of electrodes and electrode/electrolyte interfaces, in sharp contrast to other batteries equipped with SIPE membranes that display appreciable operability only at elevated temperatures (>60 °C). The performance is comparable to that of batteries using liquid electrolyte of inorganic salt, and the batteries exhibit excellent cycle life and rate performance. This significant widening of battery operation temperatures coupled with the inherent flexibility and robustness of the SIPE membranes makes it possible to develop thin and flexible Li-ion batteries for a broad range of applications.

  19. Temperature-programmed technique accompanied with high-throughput methodology for rapidly searching the optimal operating temperature of MOX gas sensors.

    Science.gov (United States)

    Zhang, Guozhu; Xie, Changsheng; Zhang, Shunping; Zhao, Jianwei; Lei, Tao; Zeng, Dawen

    2014-09-08

    A combinatorial high-throughput temperature-programmed method to obtain the optimal operating temperature (OOT) of gas sensor materials is demonstrated here for the first time. A material library consisting of SnO2, ZnO, WO3, and In2O3 sensor films was fabricated by screen printing. Temperature-dependent conductivity curves were obtained by scanning this gas sensor library from 300 to 700 K in different atmospheres (dry air, formaldehyde, carbon monoxide, nitrogen dioxide, toluene and ammonia), giving the OOT of each sensor formulation as a function of the carrier and analyte gases. A comparative study of the temperature-programmed method and a conventional method showed good agreement in measured OOT.

  20. The dew point temperature as a criterion for optimizing the operating conditions of proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Berning, Torsten

    2012-01-01

    of the operating pressure, the stoichiometric flow ratios and the net drag coefficient of water through the membrane. Then, computational modeling results obtained with a previously published model are analyzed and compared with the dew point charts, and it is demonstrated how cell flooding or membrane dry-out can...... be predicted a priori with the aid of these diagrams. Finally, guidelines for the desired cell operating temperature based on the expected dew point temperatures are developed. In the current work these guidelines are limited to the interdigitated flow field design, and they are likely to be different...

  1. X-1E Loaded in B-29 Mothership on Ramp

    Science.gov (United States)

    1955-01-01

    The Bell Aircraft Corporation X-1E airplane being loaded under the mothership, Boeing B-29. The X-planes had originally been lowered into a loading pit and the launch aircraft towed over the pit, where the rocket plane was hoisted by belly straps into the bomb bay. By the early 1950s a hydraulic lift had been installed on the ramp at the NACA High-Speed Flight Station to elevate the launch aircraft and then lower it over the rocket plane for mating.

  2. Getting to the On-ramp of the Information Superhighway

    Science.gov (United States)

    1996-01-01

    manager may elect to automatically forward all incoming e- mail from selected senders to his deputy. It is not necessary to have an AMH installed if users...establish a process to quickly identify the important and rou- tine messages. Most e- mail systems have an inbox which sorts unread e- mail and...messages FYI: for all �unofficial� For Your In- 27 Getting to the On-Ramp formation, or optional messages E- mail should also be � sender friendly.� Some

  3. R&D on an Ultra-Thin Composite Membrane for High-Temperature Operation in PEMFC. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Yuh, C.-Y.

    2003-10-06

    FuelCell Energy developed a novel high-temperature proton exchange membrane for PEM fuel cells for building applications. The laboratory PEM fuel cell successfully operated at 100-400{supdegree}C and low relative humidity to improve CO tolerance, mitigate water and thermal management challenges, and reduce membrane cost. The developed high-temperature membrane has successfully completed 500h 120C endurance testing.

  4. Analysis of the Impact of Decreasing District Heating Supply Temperature on Combined Heat and Power Plant Operation

    OpenAIRE

    Bolonina Alona; Bolonins Genadijs; Blumberga Dagnija

    2014-01-01

    District heating systems are widely used to supply heat to different groups of heat consumers. The district heating system offers great opportunities for combined heat and power production. In this paper decreasing district heating supply temperature is analysed in the context of combined heat and power plant operation. A mathematical model of a CHP plant is developed using both empirical and theoretical equations. The model is used for analysis of modified CHP plant operation modes with redu...

  5. Multi-cycle operation of enhanced biological phosphorus removal (EBPR) with different carbon sources under high temperature.

    Science.gov (United States)

    Shen, Nan; Chen, Yun; Zhou, Yan

    2017-05-01

    Many studies reported that it is challenging to apply enhanced biological phosphorus removal (EBPR) process at high temperature. Glycogen accumulating organisms (GAOs) could easily gain their dominance over poly-phosphate accumulating organisms (PAOs) when the operating temperature was in the range of 25 °C-30 °C. However, a few successful EBPR processes operated at high temperature have been reported recently. This study aimed to have an in-depth understanding on the impact of feeding strategy and carbon source types on EBPR performance in tropical climate. P-removal performance of two EBPR systems was monitored through tracking effluent quality and cyclic studies. The results confirmed that EBPR was successfully obtained and maintained at high temperature with a multi-cycle strategy. More stable performance was observed with acetate as the sole carbon source compared to propionate. Stoichiometric ratios of phosphorus and carbon transformation during both anaerobic and aerobic phases were higher at high temperature than low temperature (20±1 °C) except anaerobic PHA/C ratios within most of the sub-cycles. Furthermore, the fractions of PHA and glycogen in biomass were lower compared with one-cycle pulse feed operation. The microbial community structure was more stable in acetate-fed sequencing batch reactor (C2-SBR) than that in propionate-fed reactor (C3-SBR). Accumulibacter Clade IIC was found to be highly abundant in both reactors. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Oxygen uptake kinetics during incremental- and decremental-ramp cycle ergometry.

    Science.gov (United States)

    Ozyener, Fadil; Rossiter, Harry B; Ward, Susan A; Whipp, Brian J

    2011-01-01

    The pulmonary oxygen uptake (VO2) response to incremental-ramp cycle ergometry typically demonstrates lagged-linear first-order kinetics with a slope of ~10-11 ml·min(-1)·W(-1), both above and below the lactate threshold (θL), i.e. there is no discernible VO2 slow component (or "excess" VO2) above θL. We were interested in determining whether a reverse ramp profile would yield the same response dynamics. Ten healthy males performed a maximum incremental -ramp (15-30 W·min(-1), depending on fitness). On another day, the work rate (WR) was increased abruptly to the incremental maximum and then decremented at the same rate of 15-30 W.min(-1) (step-decremental ramp). Five subjects also performed a sub-maximal ramp-decremental test from 90% of θL. VO2 was determined breath-by-breath from continuous monitoring of respired volumes (turbine) and gas concentrations (mass spectrometer). The incremental-ramp VO2-WR slope was 10.3 ± 0.7 ml·min(-1)·W(-1), whereas that of the descending limb of the decremental ramp was 14.2 ± 1.1 ml·min(-1)·W(-1) (p incremental-ramp. This suggests that the VO2 response in the supra-θL domain of incremental-ramp exercise manifest not actual, but pseudo, first-order kinetics. Key pointsThe slope of the decremental-ramp response is appreciably greater than that of the incremental.The response dynamics in supra-θL domain of the incremental-ramp appear not to manifest actual first-order kinetics.The mechanisms underlying the different dynamic response behaviour for incremental and decremental ramps are presently unclear.

  7. Verification Plan for the Concrete Temperature of the MACSTOR/KN-400 Module under Transient State Considering Actual Operating Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kyung Ho; Park, Jeong Eun [KHNP, Daejeon (Korea, Republic of)

    2009-10-15

    This paper covers a verification plan of the results of heat transfer analysis in the MACSTOR/KN-400 on a transient state basis. The transient state reflects several natural environment parameters such as solar loads and daily temperature variations. These factors seriously affect analysis results in terms of concrete temperature and temperature gradients. There are two objectives to verifying the heat analysis results under transient state. First, there is the need to meet the request of the regular body to confirm that concrete temperature stays below the level of the design criteria. Second, it is necessary to recognize how much conservative the analysis is. In actual operating conditions, concrete temperature would be reduced by less conservative conditions.

  8. Optimizing solid oxide fuel cell cathode processing route for intermediate temperature operation

    DEFF Research Database (Denmark)

    Ortiz-Vitoriano, N.; Bernuy-Lopez, Carlos; Ruiz de Larramendi, I.;

    2013-01-01

    -priced raw material and cost-effective production techniques.In this work the perovskite-type La0.6Ca0.4Fe0.8Ni0.2O3 (LCFN) oxide has been used in order to optimize intermediate temperature SOFC cathode processing route. The advantages this material presents arise from the low temperature powder calcination...... of temperatures (800-1000°C). Scanning Electron Microscopy (SEM) studies revealed porous electrode microstructures, even when sintered at a temperature of just 800°C. The competitive performance of the electrodes sintered at low temperatures, combined with the low raw material cost, make these electrodes...

  9. Tailored ramp wave generation in gas gun experiments

    Directory of Open Access Journals (Sweden)

    Cotton Matthew

    2015-01-01

    Full Text Available Gas guns are traditionally used as platforms to introduce a planar shock wave to a material using plate impact methods, generating states on the Hugoniot. The ability to deliver a ramp wave to a target during a gas gun experiment enables access to different regions of the equation-of-state surface, making it a valuable technique for characterising material behaviour. Previous techniques have relied on the use of multi-material impactors to generate a density gradient, which can be complex to manufacture. In this paper we describe the use of an additively manufactured steel component consisting of an array of tapered spikes which can deliver a ramp wave over ∼ 2 μs. The ability to tailor the input wave by varying the component design is discussed, an approach which makes use of the design freedom offered by additive manufacturing techniques to rapidly iterate the spike profile. Results from gas gun experiments are presented to evaluate the technique, and compared with 3D hydrodynamic simulations.

  10. Prediction of air temperature in the aircraft cabin under different operational conditions

    Directory of Open Access Journals (Sweden)

    Fišer J.

    2013-04-01

    Full Text Available This paper deals with the prediction of the air temperature in the aircraft cabin by means of Computational Fluid Dynamics. The simulations are performed on the CFD model which is based on geometry and cabin interior arrangement of the Flight Test Facility (FTF located at Fraunhofer IBP, Germany. The experimental test flights under three different cabin temperatures were done in FTF and the various data were gathered during these flights. Air temperature in the cabin was measured on probes located near feet, torso and head of each passenger and also surface temperature and air temperature distributed from inlets were measured. The data were firstly analysed in order to obtain boundary conditions for cabin surfaces and inlets. Then the results of air temperature from the simulations were compared with measured data. The suitability and accuracy of the CFD approach for temperature prediction is discussed.

  11. Effects of Engine Cooling Water Temperature on Performance and Emission Characteristics of a Ci Engine Operated with Biofuel Blend

    Directory of Open Access Journals (Sweden)

    Abul Hossain

    2017-03-01

    Full Text Available The temperature of the coolant is known to have significant influence on engine performance and emissions. Whereas existing literature describes the effects of coolant temperature in engines using fossil derived fuels, very few studies have investigated these effects when biofuel is used. In this study, Jatropha oil was blended separately with ethanol and butanol. It was found that the 80% jatropha oil + 20% butanol blend was the most suitable alternative, as its properties were closest to that of fossil diesel. The coolant temperature was varied between 50°C and 95°C. The combustion process enhanced for both diesel and biofuel blend, when the coolant temperature was increased. The carbon dioxide emissions for both diesel and biofuel blend were observed to increase with temperature. The carbon monoxide, oxygen and lambda values were observed to decrease with temperature. When the engine was operated using diesel, nitrogen oxides emissions correlated in an opposite manner to smoke opacity; however, nitrogen oxides emissions and smoke opacity correlated in an identical manner for biofuel blend. Brake specific fuel consumption was observed to decrease as the temperature was increased and was higher on average when the biofuel was used. The study concludes that both biofuel blend and fossil diesel produced identical correlations between coolant temperature and engine performance. The trends of nitrogen oxides and smoke emissions with cooling temperatures were not identical to fossil diesel when biofuel blend was used in the engine.

  12. Temperature effect on hydrocarbon deposition on molybdenum mirrors under ITER-relevant long-term plasma operation

    NARCIS (Netherlands)

    Rapp, J.; van Rooij, G. J.; Litnovsky, A.; Marot, L.; De Temmerman, G.; Westerhout, J.; Zoethout, E.

    2009-01-01

    Optical diagnostics in ITER will rely on mirrors near the plasma and the deterioration of the reflectivity is a concern. The effect of temperature on the deposition efficiency of hydrocarbons under long-term operation conditions similar to ITER was investigated in the linear plasma generator

  13. Temperature effects on particulate emissions from DPF-equipped diesel trucks operating on conventional and biodiesel fuels

    Science.gov (United States)

    Two diesel trucks equipped with a particulate filter (DPF) were tested at two ambient temperatures (70oF and 20oF), fuels (ultra low sulfur diesel (ULSD) and biodiesel (B20)) and operating loads (a heavy and light weight). The test procedure included three driving cycles, a cold ...

  14. Temperature effect on hydrocarbon deposition on molybdenum mirrors under ITER-relevant long-term plasma operation

    NARCIS (Netherlands)

    Rapp, J.; van Rooij, G. J.; Litnovsky, A.; Marot, L.; De Temmerman, G.; Westerhout, J.; Zoethout, E.

    2009-01-01

    Optical diagnostics in ITER will rely on mirrors near the plasma and the deterioration of the reflectivity is a concern. The effect of temperature on the deposition efficiency of hydrocarbons under long-term operation conditions similar to ITER was investigated in the linear plasma generator Pilot-P

  15. Animal Thermoregulation and the Operative Environmental (Equivalent) Temperature. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Process.

    Science.gov (United States)

    Stevenson, R. D.

    These materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. Thermoregulation is defined as the ability of an organism to modify its body temperature. This…

  16. Operative temperature drifts and occupant satisfaction with thermal environment in three office buildings using radiant heating/ cooling system

    DEFF Research Database (Denmark)

    Kolarik, Jakub; Toftum, Jørn; Olesen, Bjarne W.

    2015-01-01

    The objective of this study was to analyse operative temperature drifts and occupant satisfaction with thermal environment in office buildings utilizing embedded radiant heating/cooling systems. Three office buildings were investigated: Town Hall in Viborg, Denmark (floor area 19400 m2), IDOM...

  17. Towards a Future of District Heating Systems with Low-Temperature Operation together with Non-Fossil Fuel Heat Sources

    DEFF Research Database (Denmark)

    Tol, Hakan; Dinçer, Ibrahim; Svendsen, Svend

    2012-01-01

    This study focused on investigation of non-fossil fuel heat sources to be supplied to low-energy district heating systems operating in low temperature such as 55 C and 25 C in terms of, respectively, supply and return. Vast variety of heat sources classed in categories such as fossil fuel, renewa...

  18. A fuel cell operating between room temperature and 250 C based on a new phosphoric acid based composite electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Rong [Department of Chemistry, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); Xu, Xiaoxiang; Irvine, John T.S. [School of Chemistry, University of St Andrews, St Andrews, Fife KY16 9ST (United Kingdom); Tao, Shanwen [Department of Chemistry, Heriot-Watt University, Edinburgh EH14 4AS (United Kingdom); School of Chemistry, University of St Andrews, St Andrews, Fife KY16 9ST (United Kingdom)

    2010-10-15

    A phosphoric acid based composite material with core-shell microstructure has been developed to be used as a new electrolyte for fuel cells. A fuel cell based on this electrolyte can operate at room temperature indicating leaching of H{sub 3}PO{sub 4} with liquid water is insignificant at room temperature. This will help to improve the thermal cyclability of phosphoric acid based electrolyte to make it easier for practical use. The conductivity of this H{sub 3}PO{sub 4}-based electrolyte is stable at 250 C with addition of the hydrophilic inorganic compound BPO{sub 4} forming a core-shell microstructure which makes it possible to run a PAFC at a temperature above 200 C. The core-shell microstructure retains after the fuel cell measurements. A power density of 350 mW/cm{sup 2} for a H{sub 2}/O{sub 2} fuel cell has been achieved at 200 C. The increase in operating temperature does not have significant benefit to the performance of a H{sub 2}/O{sub 2} fuel cell. For the first time, a composite electrolyte material for phosphoric acid fuel cells which can operate in a wide range of temperature has been evaluated but certainly further investigation is required. (author)

  19. Operative temperature and thermal sensation assessments in non-air-conditioned multi-storey hostels in Malaysia

    Energy Technology Data Exchange (ETDEWEB)

    Dahlan, N.D. [Department of Architecture, Faculty of Design and Architecture, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Jones, P.J.; Alexander, D.K. [Welsh School of Architecture, Cardiff University, Bute Building, King Edward VII Avenue, CF10 3NB (United Kingdom)

    2011-02-15

    This study assessed the influences of operative temperature on occupants' perceptions of indoor thermal condition in three non-air-conditioned multi-storey hostels in Klang Valley, Malaysia. The thermal conditions of 24 measured rooms were recorded with and without an operating ceiling fan from May until July 2007. Measurements were made simultaneously at three different floor levels, namely, at the first, fifth and top floor of each of the case study hostels. A questionnaire survey was completed by 298 female student occupants of the same case study hostels. The results suggested that even though a significance above p < 0.01 was recorded between the operative temperatures with and without fan operation, the temperature difference remained small, i.e., from 0.5 K to 1 K. The findings of the questionnaire survey showed that the occupants perceived the thermal conditions in rooms that were shaded with a projected balcony (shading ratio of 0.9), a long roof overhang (shading ratio of 1.6) and an operable window-to-wall ratio of 0.3 to be thermally comfortable. (author)

  20. Nonequilibrium dynamics of the Bose-Hubbard model: a projection-operator approach.

    Science.gov (United States)

    Trefzger, C; Sengupta, K

    2011-03-04

    We study the phase diagram and nonequilibrium dynamics involving ramp of the hopping amplitude J(t)=Jt/τ with ramp time τ of the Bose-Hubbard model at zero temperature using a projection-operator formalism which allows us to incorporate the effects of quantum fluctuations beyond mean-field approximations in the strong-coupling regime. Our formalism yields a phase diagram which provides a near exact match with quantum Monte Carlo results in three dimensions. We also compute the residual energy Q, the superfluid order parameter Δ(t), the equal-time order parameter correlation function C(t), and the wave function overlap F which yields the defect formation probability P during nonequilibrium dynamics of the model. We find that Q, F, and P do not exhibit the expected universal scaling. We explain this absence of universality and show that our results compare well with recent experiments.

  1. Low-threshold room-temperature continuous-wave operation of a terahertz difference-frequency quantum cascade laser source

    Science.gov (United States)

    Fujita, Kazuue; Ito, Akio; Hitaka, Masahiro; Dougakiuchi, Tatsuo; Edamura, Tadataka

    2017-08-01

    The performance of a room-temperature continuous-wave (CW) terahertz source based on intracavity difference-frequency generation in a mid-infrared (λ ∼ 6.8 µm) quantum cascade laser with a dual-upper-state active region is reported. The fabricated buried heterostructure device, with a two-section buried distributed feedback grating, operates at two mid-infrared wavelengths and demonstrates a terahertz output of 2.92 THz with a very low threshold current density of 0.89 kA/cm2 in pulsed operation. Consequently, despite an epitaxial-side-up mounting configuration, the device achieves CW operation at room temperature in which a low CW threshold current density of 1.3 kA/cm2 is obtained.

  2. State of the art of AIM LWIR and VLWIR MCT 2D focal plane detector arrays for higher operating temperatures

    Science.gov (United States)

    Figgemeier, H.; Hanna, S.; Eich, D.; Mahlein, K.-M.; Fick, W.; Schirmacher, W.; Thöt, R.

    2016-05-01

    In this paper AIM presents its latest results on both n-on-p and p-on-n low dark current planar MCT photodiode technology LWIR and VLWIR two-dimensional focal plane detector arrays with a cut-off wavelength >11μm at 80K and a 640x512 pixel format at a 20μm pitch. Thermal dark currents significantly reduced as compared to `Tennant's Rule 07' at a yet good detection efficiency >60% as well as results from NETD and photo response performance characterization are presented. The demonstrated detector performance paces the way for a new generation of higher operating temperature LWIR MCT FPAs with a <30mK NETD up to a 110K detector operating temperature and with good operability.

  3. Simulating potential structural and operational changes for Detroit Dam on the North Santiam River, Oregon, for downstream temperature management

    Science.gov (United States)

    Buccola, Norman L.; Rounds, Stewart A.; Sullivan, Annett B.; Risley, John C.

    2012-01-01

    Detroit Dam was constructed in 1953 on the North Santiam River in western Oregon and resulted in the formation of Detroit Lake. With a full-pool storage volume of 455,100 acre-feet and a dam height of 463 feet, Detroit Lake is one of the largest and most important reservoirs in the Willamette River basin in terms of power generation, recreation, and water storage and releases. The U.S. Army Corps of Engineers operates Detroit Dam as part of a system of 13 reservoirs in the Willamette Project to meet multiple goals, which include flood-damage protection, power generation, downstream navigation, recreation, and irrigation. A distinct cycle in water temperature occurs in Detroit Lake as spring and summer heating through solar radiation creates a warm layer of water near the surface and isolates cold water below. Controlling the temperature of releases from Detroit Dam, therefore, is highly dependent on the location, characteristics, and usage of the dam's outlet structures. Prior to operational changes in 2007, Detroit Dam had a well-documented effect on downstream water temperature that was problematic for endangered salmonid fish species, releasing water that was too cold in midsummer and too warm in autumn. This unnatural seasonal temperature pattern caused problems in the timing of fish migration, spawning, and emergence. In this study, an existing calibrated 2-dimensional hydrodynamic water-quality model [CE-QUAL-W2] of Detroit Lake was used to determine how changes in dam operation or changes to the structural release points of Detroit Dam might affect downstream water temperatures under a range of historical hydrologic and meteorological conditions. The results from a subset of the Detroit Lake model scenarios then were used as forcing conditions for downstream CE-QUAL-W2 models of Big Cliff Reservoir (the small reregulating reservoir just downstream of Detroit Dam) and the North Santiam and Santiam Rivers. Many combinations of environmental, operational, and

  4. Water temperature effects from simulated dam operations and structures in the Middle Fork Willamette River, western Oregon

    Science.gov (United States)

    Buccola, Norman L.; Turner, Daniel F.; Rounds, Stewart A.

    2016-09-14

    Significant FindingsStreamflow and water temperature in the Middle Fork Willamette River (MFWR), western Oregon, have been regulated and altered since the construction of Lookout Point, Dexter, and Hills Creek Dams in 1954 and 1961, respectively. Each year, summer releases from the dams typically are cooler than pre-dam conditions, with the reverse (warmer than pre-dam conditions) occurring in autumn. This pattern has been detrimental to habitat of endangered Upper Willamette River (UWR) Chinook salmon (Oncorhynchus tshawytscha) and UWR winter steelhead (O. mykiss) throughout multiple life stages. In this study, scenarios testing different dam-operation strategies and hypothetical dam-outlet structures were simulated using CE-QUAL-W2 hydrodynamic/temperature models of the MFWR system from Hills Creek Lake (HCR) to Lookout Point (LOP) and Dexter (DEX) Lakes to explore and understand the efficacy of potential flow and temperature mitigation options.Model scenarios were run in constructed wet, normal, and dry hydrologic calendar years, and designed to minimize the effects of Hills Creek and Lookout Point Dams on river temperature by prioritizing warmer lake surface releases in May–August and cooler, deep releases in September–December. Operational scenarios consisted of a range of modified release rate rules, relaxation of power-generation constraints, variations in the timing of refill and drawdown, and maintenance of different summer maximum lake levels at HCR and LOP. Structural scenarios included various combinations of hypothetical floating outlets near the lake surface and hypothetical new outlets at depth. Scenario results were compared to scenarios using existing operational rules that give temperature management some priority (Base), scenarios using pre-2012 operational rules that prioritized power generation over temperature management (NoBlend), and estimated temperatures from a without-dams condition (WoDams).Results of the tested model scenarios led

  5. Junction temperature estimation method for a 600 V, 30A IGBT module during converter operation

    DEFF Research Database (Denmark)

    Choi, U. M.; Blaabjerg, F.; Iannuzzo, F.

    2015-01-01

    This paper proposes an accurate method to estimate the junction temperature using the on-state collector-emitter voltage at high current. By means of the proposed method, the estimation error which comes from the different temperatures of the interconnection materials in the module is compensated...

  6. Reattachment heating upstream of short compression ramps in hypersonic flow

    Science.gov (United States)

    Estruch-Samper, David

    2016-05-01

    Hypersonic shock-wave/boundary-layer interactions with separation induce unsteady thermal loads of particularly high intensity in flow reattachment regions. Building on earlier semi-empirical correlations, the maximum heat transfer rates upstream of short compression ramp obstacles of angles 15° ⩽ θ ⩽ 135° are here discretised based on time-dependent experimental measurements to develop insight into their transient nature (Me = 8.2-12.3, Re_h= 0.17× 105-0.47× 105). Interactions with an incoming laminar boundary layer experience transition at separation, with heat transfer oscillating between laminar and turbulent levels exceeding slightly those in fully turbulent interactions. Peak heat transfer rates are strongly influenced by the stagnation of the flow upon reattachment close ahead of obstacles and increase with ramp angle all the way up to θ =135°, whereby rates well over two orders of magnitude above the undisturbed laminar levels are intermittently measured (q'_max>10^2q_{u,L}). Bearing in mind the varying degrees of strength in the competing effect between the inviscid and viscous terms—namely the square of the hypersonic similarity parameter (Mθ )^2 for strong interactions and the viscous interaction parameter bar{χ } (primarily a function of Re and M)—the two physical factors that appear to most globally encompass the effects of peak heating for blunt ramps (θ ⩾ 45°) are deflection angle and stagnation heat transfer, so that this may be fundamentally expressed as q'_max∝ {q_{o,2D}} θ ^2 with further parameters in turn influencing the interaction to a lesser extent. The dominant effect of deflection angle is restricted to short obstacle heights, where the rapid expansion at the top edge of the obstacle influences the relaxation region just downstream of reattachment and leads to an upstream displacement of the separation front. The extreme heating rates result from the strengthening of the reattaching shear layer with the increase in

  7. Dirac point and transconductance of top-gated graphene field-effect transistors operating at elevated temperature

    Energy Technology Data Exchange (ETDEWEB)

    Hopf, T.; Vassilevski, K. V., E-mail: k.vasilevskiy@ncl.ac.uk; Escobedo-Cousin, E.; King, P. J.; Wright, N. G.; O' Neill, A. G.; Horsfall, A. B.; Goss, J. P. [School of Electrical and Electronic Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU (United Kingdom); Wells, G. H.; Hunt, M. R. C. [Department of Physics, Durham University, Durham DH1 3LE (United Kingdom)

    2014-10-21

    Top-gated graphene field-effect transistors (GFETs) have been fabricated using bilayer epitaxial graphene grown on the Si-face of 4H-SiC substrates by thermal decomposition of silicon carbide in high vacuum. Graphene films were characterized by Raman spectroscopy, Atomic Force Microscopy, Scanning Tunnelling Microscopy, and Hall measurements to estimate graphene thickness, morphology, and charge transport properties. A 27 nm thick Al₂O₃ gate dielectric was grown by atomic layer deposition with an e-beam evaporated Al seed layer. Electrical characterization of the GFETs has been performed at operating temperatures up to 100 °C limited by deterioration of the gate dielectric performance at higher temperatures. Devices displayed stable operation with the gate oxide dielectric strength exceeding 4.5 MV/cm at 100 °C. Significant shifting of the charge neutrality point and an increase of the peak transconductance were observed in the GFETs as the operating temperature was elevated from room temperature to 100 °C.

  8. Quantification of tsunami-induced flows on a Mediterranean carbonate ramp reveals catastrophic evolution

    NARCIS (Netherlands)

    Slootman, A.; Cartigny, M.J.B.; Moscariello, A.; Chiaradia, M.; de Boer, P.L.

    2016-01-01

    Cool-water carbonates are the dominant limestones in the Mediterranean Basin since the Early Pliocene. Their deposition typically resulted in ramp morphologies due to high rates of resedimentation. Several such fossil carbonate ramps are characterised by a bimodal facies stacking pattern, where

  9. Thermal ramp tritium release in COBRA-1A2 C03 beryllium pebbles

    Energy Technology Data Exchange (ETDEWEB)

    Baldwin, D.L. [Pacific Northwest National Lab., Richland, WA (United States)

    1998-03-01

    Tritium release kinetics, using the method of thermal ramp heating at three linear ramp rates, were measured on the COBRA-1A2 C03 1-mm beryllium pebbles. This report includes a brief discussion of the test, and the test data in graph format.

  10. Effects of compression and expansion ramp fuel injector configuration on scramjet combustion and heat transfer

    Science.gov (United States)

    Stouffer, Scott D.; Baker, N. R.; Capriotti, D. P.; Northam, G. B.

    1993-01-01

    A scramjet combustor with four wall-ramp injectors containing Mach-1.7 fuel jets in the base of the ramps was investigated experimentally. During the test program, two swept ramp injector designs were evaluated. One swept-ramp model had 10-deg compression-ramps and the other had 10-deg expansion cavities between flush wall ramps. The scramjet combustor model was instrumented with pressure taps and heat-flux gages. The pressure measurements indicated that both injector configurations were effective in promoting mixing and combustion. Autoignition occurred for the compression-ramp injectors, and the fuel began to burn immediately downstream of the injectors. In tests of the expansion ramps, a pilot was required to ignite the fuel, and the fuel did not burn for a distance of at least two gaps downstream of the injectors. Once initiated, combustion was rapid in this configuration. Heat transfer measurements showed that the heat flux differed greatly both across the width of the combustor and along the length of the combustor.

  11. Heat and fuel coupled operation of a high temperature polymer electrolyte fuel cell with a heat exchanger methanol steam reformer

    Science.gov (United States)

    Schuller, G.; Vázquez, F. Vidal; Waiblinger, W.; Auvinen, S.; Ribeirinha, P.

    2017-04-01

    In this work a methanol steam reforming (MSR) reactor has been operated thermally coupled to a high temperature polymer electrolyte fuel cell stack (HT-PEMFC) utilizing its waste heat. The operating temperature of the coupled system was 180 °C which is significantly lower than the conventional operating temperature of the MSR process which is around 250 °C. A newly designed heat exchanger reformer has been developed by VTT (Technical Research Center of Finland LTD) and was equipped with commercially available CuO/ZnO/Al2O3 (BASF RP-60) catalyst. The liquid cooled, 165 cm2, 12-cell stack used for the measurements was supplied by Serenergy A/S. The off-heat from the electrochemical fuel cell reaction was transferred to the reforming reactor using triethylene glycol (TEG) as heat transfer fluid. The system was operated up to 0.4 A cm-2 generating an electrical power output of 427 Wel. A total stack waste heat utilization of 86.4% was achieved. It has been shown that it is possible to transfer sufficient heat from the fuel cell stack to the liquid circuit in order to provide the needed amount for vaporizing and reforming of the methanol-water-mixture. Furthermore a set of recommendations is given for future system design considerations.

  12. Generation of Optical Vortices by Linear Phase Ramps

    Directory of Open Access Journals (Sweden)

    Sunil Vyas

    2012-01-01

    Full Text Available Generation of optical vortices using linear phase ramps is experimentally demonstrated. When two regions of a wavefront have opposite phase gradients then along the line of phase discontinuity vortices can be generated. It is shown that vortices can evolve during propagation even with the unequal magnitude of tilt in the two regions of the wavefront. The number of vortices and their location depend upon the magnitude of tilt. vortex generation is experimentally realized by encoding phase mask on spatial light modulator and their presence is detected interferometrically. Numerical simulation has been performed to calculate the diffracted intensity distribution from the phase mask, and presence of vortices in the diffracted field is detected by computational techniques.

  13. [Ramp lesions : Tips and tricks in diagnostics and therapy].

    Science.gov (United States)

    Seil, R; Hoffmann, A; Scheffler, S; Theisen, D; Mouton, C; Pape, D

    2017-09-14

    There is an increasing biomechanical and anatomical understanding of the different types of meniscal lesions. Lesions of the posterior part of the medial meniscus in the meniscosynovial area have recently received increased attention. They generally occur in association with anterior cruciate ligament (ACL) injuries. They are often missed ("hidden lesions") due to the fact that they cannot be seen by routine anterior arthroscopic inspection. Furthermore, meniscosynovial lesions play a role in anteroposterior knee laxity and, as such, they may be a cause of failure of ACL reconstruction or of postoperative persistent laxity. Little information is available regarding their cause with respect to injury mechanism, natural history, biomechanical implications, healing potential and treatment options. This article presents an overview of the currently available knowledge of these ramp lesions, their possible pathomechanism, classification, biomechanical relevance as well as repair techniques.

  14. Effect of lubricant jet location on spiral bevel gear operating temperatures

    Science.gov (United States)

    Handschuh, Robert F.

    1992-04-01

    An experimental study was conducted to determine the effect of lubricant jet location on spiral bevel gear bulk temperatures. Transient surface temperatures were also measured. Tests were conducted on aircraft quality spiral bevel gears in a closed loop test facility. Thermocoupled pinions and an infrared microscope were used to collect the pertinent data. A single fan jet lubricated the test gears. Lubricant flow rate (lubricant jet pressure) and applied torque were also varied. The results showed that jet placement had a significant effect on the gear bulk temperatures.

  15. Potential Field Cellular Automata Model for Pedestrian Evacuation in a Domain with a Ramp

    Directory of Open Access Journals (Sweden)

    Xiao-Xia Jian

    2014-01-01

    Full Text Available We propose a potential field cellular automata model with a pushing force field to simulate the pedestrian evacuation in a domain with a ramp. We construct a cost potential depending on the ramp angle and introduce a function to evaluate the pushing force, which is related to the cost and the desired direction of pedestrian. With increase of crowd density, there is no empty space for pedestrian moving forward; pedestrian will purposefully push another pedestrian on her or his desired location to arrive the destination quickly. We analyse the relationship between the slope of ramp and the pushing force and investigate the changing of injured situations with the changing of the slope of ramp. When the number of pedestrians and the ramp angle arrive at certain critical points, the Domino effect will be simulated by this proposed model.

  16. Generation of ramp waves using variable areal density flyers

    Science.gov (United States)

    Winter, R. E.; Cotton, M.; Harris, E. J.; Chapman, D. J.; Eakins, D.

    2016-07-01

    Ramp loading using graded density impactors as flyers in gas-gun-driven plate impact experiments can yield new and useful information about the equation of state and the strength properties of the loaded material. Selective Laser Melting, an additive manufacturing technique, was used to manufacture a graded density flyer, termed the "bed-of-nails" (BON). A 2.5-mm-thick × 99.4-mm-diameter solid disc of stainless steel formed a base for an array of tapered spikes of length 5.5 mm and spaced 1 mm apart. The two experiments to test the concept were performed at impact velocities of 900 and 1100 m/s using the 100-mm gas gun at the Institute of Shock Physics at Imperial College London. In each experiment, a BON flyer was impacted onto a copper buffer plate which helped to smooth out perturbations in the wave profile. The ramp delivered to the copper buffer was in turn transmitted to three tantalum targets of thicknesses 3, 5 and 7 mm, which were mounted in contact with the back face of the copper. Heterodyne velocimetry (Het-V) was used to measure the velocity-time history, at the back faces of the tantalum discs. The wave profiles display a smooth increase in velocity over a period of ˜ 2.5 μs, with no indication of a shock jump. The measured profiles have been analysed to generate a stress vs. volume curve for tantalum. The results have been compared with the predictions of the Sandia National Laboratories hydrocode, CTH.

  17. Solid polymer electrolyte water electrolyser based on Nafion-TiO{sub 2} composite membrane for high temperature operation

    Energy Technology Data Exchange (ETDEWEB)

    Baglio, V.; Antonucci, V.; Arico, A.S. [CNR-ITAE, Messina (Italy); Matteucci, F.; Martina, F.; Zama, I. [Tozzi Renewable Energy SpA, Mezzano (Italy); Ciccarella, G. [National Nanotechnology Laboratory (NNL) of INFM-CNR, Distretto Tecnologico ISUFI, Innovazione, Universita del Salento, Lecce (Italy); Arriaga, L.G. [Centro de Investigacion y Desarrollo Tecnologico en Electroquimica, Queretaro Sanfandila (Mexico); Ornelas, R.

    2009-06-15

    A composite Nafion-TiO{sub 2} membrane was manufactured by a recast procedure, using an in-house prepared TiO{sub 2}. This membrane has shown promising properties for high temperature operation in an SPE electrolyser allowing to achieve higher performance with respect to a commercial Nafion 115 membrane. This effect is mainly due to the water retention properties of the TiO{sub 2} filler. A promising increase in electrical efficiency was recorded at low current densities for the composite membrane-based SPE electrolyser at high temperature compared to conventional membrane-based devices. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  18. Room-temperature cw operation of an efficient miniaturized Nd:YAG laser end-pumped by a superluminescent diode

    Energy Technology Data Exchange (ETDEWEB)

    Washio, K.; Iwamoto, K.; Inoue, K.; Hino, I.; Matsumoto, S.; Saito, F.

    1976-12-01

    A miniaturized Nd:YAG laser is described, in which a 3-mm-diam x 5.4-mm-long laser rod is end-pumped by a single Al/sub x/Ga/sub 1-x/As superluminescent diode (SLD) having 20-..mu..m x 1.4-nm stripe geometry. A 4.5-mW laser power was obtained at room temperature in a 1-ms pulse operation. Emitted power from the SLD was 50 mW with 1.7% external power efficiency. When continuously pumped, a 1.5-mW laser power was obtained at room temperature. (AIP)

  19. High-Voltage 1-kW dc/dc Converter Developed for Low-Temperature Operation

    Science.gov (United States)

    Patterson, Richard L.

    1998-01-01

    Recently, Lewis developed and demonstrated a high-voltage, 1-kW dc/dc converter that operates from room temperature to -184 C. A power supply designed for use in a NASA ion beam propulsion system was utilized as a starting point for the design of a low- (wide-) temperature dc/dc converter. For safety, we decided to halve the output voltage and power level, so the converter was designed for an 80-Vdc input and a 550-Vdc output at 1 kW.

  20. Comparative Studies on Low Noise Greases Operating under High Temperature Oxidation Conditions

    Institute of Scientific and Technical Information of China (English)

    Xiong Chunhua; Mi Hongying; Feng Qiang; Wu Baojie

    2014-01-01

    Oxidation induction time (OIT) testing by differential scanning calorimetry (DSC) was used to evaluate the oxidation resistance of lubricating greases. Under the high temperature condition, bearing noise was detected when grease passed the initial stable stage of oxidation. The chemical and physical structure of grease samples before and after high tem-perature oxidation were also analyzed by FT-IR spectrometry and scanning electron microscopy (SEM), then the effects of oxidation at high temperature on bearing noise were investigated. It is found out that for lithium greases, oxidation of base oil and thickener is the main reason responsible for the increasing bearing noise. As regards the polyurea greases, the change of ifber microstructure at high temperature is the main reason for the increasing bearing noise.

  1. Evaluation of Artificial Neural Network-Based Temperature Control for Optimum Operation of Building Envelopes

    National Research Council Canada - National Science Library

    Moon, Jin; Lee, Ji-Hyun; Kim, Sooyoung

    2014-01-01

    .... Numerical comparative performance tests for the ANN-based temperature control logic and conventional non-ANN-based counterpart were conducted for single skin enveloped and double skin enveloped...

  2. High-Temperature Stable Operation of Nanoribbon Field-Effect Transistors

    Directory of Open Access Journals (Sweden)

    Kim Sangsig

    2010-01-01

    Full Text Available Abstract We experimentally demonstrated that nanoribbon field-effect transistors can be used for stable high-temperature applications. The on-current level of the nanoribbon FETs decreases at elevated temperatures due to the degradation of the electron mobility. We propose two methods of compensating for the variation of the current level with the temperature in the range of 25–150°C, involving the application of a suitable (1 positive or (2 negative substrate bias. These two methods were compared by two-dimensional numerical simulations. Although both approaches show constant on-state current saturation characteristics over the proposed temperature range, the latter shows an improvement in the off-state control of up to five orders of magnitude (−5.2 × 10−6.

  3. A Plateau-Burning, Low Temperature-Operable Solid Propellant for Mars Sample Return Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Mars ascent vehicle (MAV) is required to endure a long space transit time, high-g loading during planetary entry, and high launch loads, all at low temperatures...

  4. A study on positive-feedback configuration of a bipolar SiC high temperature operational amplifier

    Science.gov (United States)

    Kargarrazi, Saleh; Lanni, Luigia; Zetterling, Carl-Mikael

    2016-02-01

    This paper reports on the design and implementation of an integrated operational amplifier in bipolar SiC, and elaborates on its operation in positive-feedback configuration.The opamp is studied in different feedback setups: closed-loop compensated amplifier, comparator with hysteresis (Schmitt trigger), and as a relaxation oscillator. Measurement results suggest a stable closed-loop opamp with ∼40 dB gain, a Schmitt trigger with constant threshold levels over a wide temperature range, and a relaxation oscillator tested up to 540 kHz. All the setups were tested from 25 °C up to 500 °C.

  5. Current Sharing inside a High Power IGBT Module at the Negative Temperature Coefficient Operating Region

    CERN Document Server

    Asimakopoulos, Panagiotis; Bongiorno, M; Thiringer, T

    2016-01-01

    This work investigates the current sharing effect of a high power Soft Punch Through IGBT module in the Negative Temperature Coefficient region. The unbalanced current sharing between two of the substrates is demonstrated for different current and temperature levels and its impact on the thermal stressing of the device is evaluated. The results indicate that the current asymmetry does not lead to a significant thermal stressing unbalance between the substrates.

  6. A novel coupled VM-PT cryocooler operating at liquid helium temperature

    Science.gov (United States)

    Pan, Changzhao; Zhang, Tong; Zhou, Yuan; Wang, Junjie

    2016-07-01

    This paper presents experimental results on a novel two-stage gas-coupled VM-PT cryocooler, which is a one-stage VM cooler coupled a pulse tube cooler. In order to reach temperatures below the critical point of helium-4, a one-stage coaxial pulse tube cryocooler was gas-coupled on the cold end of the former VM cryocooler. The low temperature inertance tube and room temperature gas reservoir were used as phase shifters. The influence of room temperature double-inlet was first investigated, and the results showed that it added excessive heat loss. Then the inertance tube, regenerator and the length of the pulse tube were researched experimentally. Especially, the DC flow, whose function is similar to the double-orifice, was experimentally studied, and shown to contribute about 0.2 K for the no-load temperature. The minimum no-load temperature of 4.4 K was obtained with a pressure ratio near 1.5, working frequency of 2.2 Hz, and average pressure of 1.73 MPa.

  7. Expanded Operational Temperature Range for Space Rated Li-Ion Batteries Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Quallion's response to this solicitation calls for expanding the nominal operation range of its space rated lithium ion cells, while maintaining their long life...

  8. Lithium Battery Electrolytes for Long Cycle Life and Wide Operating Temperature Range Project

    Data.gov (United States)

    National Aeronautics and Space Administration — New lithium battery electrolytes must be developed if these they are to be successfully deployed on NASA Platforms operating at -100oC to +100oC. Giner, Inc. has...

  9. Expanded Operational Temperature Range for Space Rated Li-Ion Batteries Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Quallion's Phase II proposal calls for expanding the nominal operation range of its space rated lithium ion cells, while maintaining their long life capabilities. To...

  10. OXYGEN UPTAKE KINETICS DURING INCREMENTAL- AND DECREMENTAL-RAMP CYCLE ERGOMETRY

    Directory of Open Access Journals (Sweden)

    Fadıl Özyener

    2011-09-01

    Full Text Available The pulmonary oxygen uptake (VO2 response to incremental-ramp cycle ergometry typically demonstrates lagged-linear first-order kinetics with a slope of ~10-11 ml·min-1·W-1, both above and below the lactate threshold (ӨL, i.e. there is no discernible VO2 slow component (or "excess" VO2 above ӨL. We were interested in determining whether a reverse ramp profile would yield the same response dynamics. Ten healthy males performed a maximum incremental -ramp (15-30 W·min-1, depending on fitness. On another day, the work rate (WR was increased abruptly to the incremental maximum and then decremented at the same rate of 15-30 W.min-1 (step-decremental ramp. Five subjects also performed a sub-maximal ramp-decremental test from 90% of ӨL. VO2 was determined breath-by-breath from continuous monitoring of respired volumes (turbine and gas concentrations (mass spectrometer. The incremental-ramp VO2-WR slope was 10.3 ± 0.7 ml·min-1·W-1, whereas that of the descending limb of the decremental ramp was 14.2 ± 1.1 ml·min-1·W-1 (p < 0.005. The sub-maximal decremental-ramp slope, however, was only 9. 8 ± 0.9 ml·min-1·W-1: not significantly different from that of the incremental-ramp. This suggests that the VO2 response in the supra-ӨL domain of incremental-ramp exercise manifest not actual, but pseudo, first-order kinetics

  11. Integrated pressure and temperature sensor with high immunity against external disturbance for flexible endoscope operation

    Science.gov (United States)

    Maeda, Yusaku; Maeda, Kohei; Kobara, Hideki; Mori, Hirohito; Takao, Hidekuni

    2017-04-01

    In this study, an integrated pressure and temperature sensor device for a flexible endoscope with long-term stability in in vivo environments was developed and demonstrated. The sensor, which is embedded in the thin wall of the disposable endoscope hood, is intended for use in endoscopic surgery. The device surface is coated with a Cr layer to prevent photoelectronic generation induced by the strong light of the endoscope. The integrated temperature sensor allows compensation for the effect of the temperature drift on a pressure signal. The fabricated device pressure resolution is 0.4 mmHg; the corresponding pressure error is 3.2 mmHg. The packaged device was used in a surgical simulation in an animal experiment. Pressure and temperature monitoring was achieved even in a pH 1 acid solution. The device enables intraluminal pressure and temperature measurements of the stomach, which facilitate the maintenance of internal stomach conditions. The applicability of the sensor was successfully demonstrated in animal experiments.

  12. Battery Internal Temperature Estimation for LiFePO4 Battery Based on Impedance Phase Shift under Operating Conditions

    Directory of Open Access Journals (Sweden)

    Jiangong Zhu

    2017-01-01

    Full Text Available An impedance-based temperature estimation method is investigated considering the electrochemical non-equilibrium with short-term relaxation time for facilitating the vehicular application. Generally, sufficient relaxation time is required for battery electrochemical equilibrium before the impedance measurement. A detailed experiment is performed to investigate the regularity of the battery impedance in short-term relaxation time after switch-off current excitation, which indicates that the impedance can be measured and also has systematical decrement with the relaxation time growth. Based on the discussion of impedance variation in electrochemical perspective, as well as the monotonic relationship between impedance phase shift and battery internal temperature in the electrochemical equilibrium state, an exponential equation that accounts for both measured phase shift and relaxation time is established to correct the measuring deviation caused by electrochemical non-equilibrium. Then, a multivariate linear equation coupled with ambient temperature is derived considering the temperature gradients between the active part and battery surface. Equations stated above are all identified with the embedded thermocouple experimentally. In conclusion, the temperature estimation method can be a valuable alternative for temperature monitoring during cell operating, and serve the functionality as an efficient implementation in battery thermal management system for electric vehicles (EVs and hybrid electric vehicles (HEVs.

  13. MEMS-Based Boiler Operation from Low Temperature Heat Transfer and Thermal Scavenging

    Directory of Open Access Journals (Sweden)

    Leland Weiss

    2012-04-01

    Full Text Available Increasing world-wide energy use and growing population growth presents a critical need for enhanced energy efficiency and sustainability. One method to address this issue is via waste heat scavenging. In this approach, thermal energy that is normally expelled to the environment is transferred to a secondary device to produce useful power output. This paper investigates a novel MEMS-based boiler designed to operate as part of a small-scale energy scavenging system. For the first time, fabrication and operation of the boiler is presented. Boiler operation is based on capillary action that drives working fluid from surrounding reservoirs across a heated surface. Pressure is generated as working fluid transitions from liquid to vapor in an integrated steamdome. In a full system application, the steam can be made available to other MEMS-based devices to drive final power output. Capillary channels are formed from silicon substrates with 100 µm widths. Varying depths are studied that range from 57 to 170 µm. Operation of the boiler shows increasing flow-rates with increasing capillary channel depths. Maximum fluid mass transfer rates are 12.26 mg/s from 170 µm channels, an increase of 28% over 57 µm channel devices. Maximum pressures achieved during operation are 229 Pa.

  14. High efficiency,high power 808nm laser array and stacked arrays optimized for elevated temperature operation

    Institute of Scientific and Technical Information of China (English)

    Crump P A; Wise D; Crum T R; DeVito M; Farmer J; Grimshaw M; Huang Z; Igl S A; Macomber S; Thiagarajan P

    2004-01-01

    Operation of 808-nm laser diode pumping at elevated temperature is crucial to many applications. Reliable operation at high power is limited by high thermal load and low catastrophic optical mirror damage (COMD) threshold at elevated temperature range. We demonstrated high efficiency and high power operation at elevated temperature with high COMD power. These results were achieved through device design optimization such as growth conditions, doping profile, and materials composition of the quantum-well and other layers. Electrical-to-optical efficiency as high as 62% was obtained through lowered threshold current, lowered series resistance and increased slope efficiency. The performance of single broad-area laser diodes scales to that of high power single bars on water-cooled copper micro-channel heatsinks or conductively-cooled CS heatsinks. No reduction in bar performance or significant spectral broadening is seen when these micro-channel coolers are assembled into 6-bar and 18-bar CW stacks for the highest power levels.

  15. Performance and endurance of a high temperature PEM fuel cell operated on methanol reformate

    DEFF Research Database (Denmark)

    Araya, Samuel Simon; Grigoras, Ionela; Zhou, Fan

    2014-01-01

    This paper analyzes the effects of methanol and water vapor on the performance of a high temperature proton exchange membrane fuel cell (HT-PEMFC) at varying temperatures, ranging from 140 °C to 180 °C. For the study, a H3PO4 – doped polybenzimidazole (PBI) – based membrane electrode assembly (MEA......) of 45 cm2 active surface area from BASF was employed. The study showed overall negligible effects of methanol-water vapor mixture slips on performance, even at relatively low simulated steam methanol reforming conversion of 90%, which corresponds to 3% methanol vapor by volume in the anode gas feed....... Temperature on the other hand has significant impact on the performance of an HT-PEMFC. To assess the effects of methanol-water vapor mixture alone, CO2 and CO are not considered in these tests. The analysis is based on polarization curves and impedance spectra registered for all the test points. After...

  16. The CO poisoning effect in PEMFCs operational at temperatures up to 200 degrees C

    DEFF Research Database (Denmark)

    Li, Qingfeng; He, Ronghuan; Gao, Ji-An;

    2003-01-01

    The CO poisoning effect on carbon-supported platinum catalysts (at a loading of 0.5 mg Pt/cm(2) per electrode! in polymer electrolyte membrane fuel cells (PEMFCs) has been investigated in a temperature range from 125 to 200 degreesC with the phosphoric acid-doped polybenzimidazole membranes...... as electrolyte. The effect is very temperature-dependent and can be sufficiently suppressed at elevated temperature. By defining the CO tolerance as a voltage loss less than 10 mV, it is evaluated that 3% CO in hydrogen can be tolerated at current densities up to 0.8 A/cm(2) at 200 degreesC, while at 125 degrees...

  17. Optimal laser wavelength for efficient laser power converter operation over temperature

    Science.gov (United States)

    Höhn, O.; Walker, A. W.; Bett, A. W.; Helmers, H.

    2016-06-01

    A temperature dependent modeling study is conducted on a GaAs laser power converter to identify the optimal incident laser wavelength for optical power transmission. Furthermore, the respective temperature dependent maximal conversion efficiencies in the radiative limit as well as in a practically achievable limit are presented. The model is based on the transfer matrix method coupled to a two-diode model, and is calibrated to experimental data of a GaAs photovoltaic device over laser irradiance and temperature. Since the laser wavelength does not strongly influence the open circuit voltage of the laser power converter, the optimal laser wavelength is determined to be in the range where the external quantum efficiency is maximal, but weighted by the photon flux of the laser.

  18. Electrochemical Impedance Spectroscopy (EIS) Characterization of Reformate-operated High Temperature PEM Fuel Cell Stack

    DEFF Research Database (Denmark)

    Sahlin, Simon Lennart; Simon Araya, Samuel; Andreasen, Søren Juhl

    2017-01-01

    their effects on a reformate-operated stack. Polarization curves were also recorded to complement the impedance analysis of the researched phenomena. An equivalent circuit model was used to estimate the different resistances at varying parameters. It showed a significantly higher low frequency resistance...... at lower stoichiometry. Both anode and cathode stoichiometric ratios had significant effects on the stack performance during the dry hydrogen and reformate operation modes. In both cases the effects faded away when sufficient mass transport was achieved, which took place at λanode= 1.3 for dry hydrogen......, λanode= 1.6 for reformate operation and λcathode= 4.The work also compared dry hydrogen, steam reforming and autothermal reforming gas feeds at160 ◦Cand showed appreciably lower performance in the case of autothermal reforming at the same stoichiometry, mainly attributable to mass transport related...

  19. Numerical solution to the problem of variational assimilation of operational observational data on the ocean surface temperature

    Science.gov (United States)

    Agoshkov, V. I.; Lebedev, S. A.; Parmuzin, E. I.

    2009-02-01

    The problem of variational assimilation of satellite observational data on the ocean surface temperature is formulated and numerically investigated in order to reconstruct surface heat fluxes with the use of the global three-dimensional model of ocean hydrothermodynamics developed at the Institute of Numerical Mathematics, Russian Academy of Sciences (INM RAS), and observational data close to the data actually observed in specified time intervals. The algorithms of the numerical solution to the problem are elaborated and substantiated, and the data assimilation block is developed and incorporated into the global three-dimensional model. Numerical experiments are carried out with the use of the Indian Ocean water area as an example. The data on the ocean surface temperature over the year 2000 are used as observational data. Numerical experiments confirm the theoretical conclusions obtained and demonstrate the expediency of combining the model with a block of assimilating operational observational data on the surface temperature.

  20. The influence of microstructure and operating temperature on the fatigue endurance of hot forged Inconel{sup ®} 718 components

    Energy Technology Data Exchange (ETDEWEB)

    Maderbacher, H., E-mail: hermann.maderbacher@unileoben.ac.at [Chair of Mechanical Engineering, Montanuniversität Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria); Oberwinkler, B., E-mail: bernd.oberwinkler@bohler-forging.com [Böhler Schmiedetechnik GmbH and Co KG, Mariazellerstraße 25, 8605 Kapfenberg (Austria); Gänser, H.-P., E-mail: hans-peter.gaenser@mcl.at [Materials Center Leoben Forschung GmbH, Roseggerstraße 12, 8700 Leoben (Austria); Tan, W., E-mail: wen.tan@unileoben.ac.at [Chair of Mechanical Engineering, Montanuniversität Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria); Rollett, M., E-mail: mathias.rollett@stud.unileoben.ac.at [Chair of Mechanical Engineering, Montanuniversität Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria); Stoschka, M., E-mail: michael.stoschka@stud.unileoben.ac.at [Chair of Mechanical Engineering, Montanuniversität Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria)

    2013-11-15

    The dependence of the fatigue behavior of hot-forged Inconel{sup ®} 718 aircraft components on the operating temperature and the material microstructure is investigated. To this purpose, possible correlations between a variety of tested microstructural parameters and the results from low-cycle fatigue (LCF) testing are analyzed using statistical methods. To identify the prevailing damage mechanisms, failure analyses are carried out on specimens tested at different temperatures. Optical and scanning electron microscopy are used for the inspection of surface crack networks and of the final fracture surface. In addition, energy dispersive X-ray (EDX) analyses are performed at the crack initiation sites to track down possible accumulations of alloying elements. The results are critically reviewed and used to propose a temperature and microstructure dependent fatigue model for predicting LCF ε⧸N-curves.

  1. The electrolyte challenge for a direct methanol-air polymer electrolyte fuel cell operating at temperatures up to 200 C

    Science.gov (United States)

    Savinell, Robert; Yeager, Ernest; Tryk, Donald; Landau, Uziel; Wainright, Jesse; Gervasio, Dominic; Cahan, Boris; Litt, Morton; Rogers, Charles; Scherson, Daniel

    1993-01-01

    Novel polymer electrolytes are being evaluated for use in a direct methanol-air fuel cell operating at temperatures in excess of 100 C. The evaluation includes tests of thermal stability, ionic conductivity, and vapor transport characteristics. The preliminary results obtained to date indicate that a high temperature polymer electrolyte fuel cell is feasible. For example, Nafion 117 when equilibrated with phosphoric acid has a conductivity of at least 0.4 Omega(exp -1)cm(exp -1) at temperatures up to 200 C in the presence of 400 torr of water vapor and methanol vapor cross over equivalent to 1 mA/cm(exp 2) under a one atmosphere methanol pressure differential at 135 C. Novel polymers are also showing similar encouraging results. The flexibility to modify and optimize the properties by custom synthesis of these novel polymers presents an exciting opportunity to develop an efficient and compact methanol fuel cell.

  2. A SQUID based read-out of sub-attoNewton force sensor operating at millikelvin temperatures

    CERN Document Server

    Usenko, O; Wijts, G; Oosterkamp, T H

    2010-01-01

    An increasing number of experiments require the use of ultrasensitive nanomechanical resonators. Relevant examples are the investigation of quantum effects in mechanical systems [1] or the detection of exceedingly small forces as in Magnetic Resonance Force Microscopy (MRFM) [2]. The force sensitivity of a mechanical resonator is typically limited by thermal fluctuations, which calls for detection methods capable of operating at ultralow temperature. Commonly used interferometric techniques, despite their excellent sensitivity, may not be an optimal choice at millikelvin temperatures, because of unwanted resonator heating caused by photon absorption. Although alternative detection techniques based on microwave cavities [3] [4] [5] have shown to perform better at ultralow temperature, these techniques still suffer from the fact that the detection sensitivity decreases as the power input is decreased. Here, we present a measurement approach based on the detection, through a Superconducting Quantum Interference ...

  3. Operation, test, research and development of the high temperature engineering test reactor (HTTR). FY1999-2001

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-05-01

    The HTTR (High Temperature Engineering Test Reactor) with the thermal power of 30 MW and the reactor outlet coolant temperature of 850/950 degC is the first high temperature gas-cooled reactor (HTGR) in Japan, which uses coated fuel particle, graphite for core components, and helium gas for primary coolant. The HTTR, which locates at the south-west area of 50,000 m{sup 2} in the Oarai Research Establishment, had been constructed since 1991 before accomplishing the first criticality on November 10, 1998. Rise to power tests of the HTTR started in September, 1999 and the rated thermal power of 30 MW and the reactor outlet coolant temperature of 850 degC was attained in December 2001. JAERI received the certificate of pre-operation test, that is, the commissioning license for the HTTR in March 2002. This report summarizes operation, tests, maintenance, radiation control, and construction of components and facilities for the HTTR as well as R and Ds on HTGRs from FY1999 to 2001. (author)

  4. On-focal-plane superconducting signal processing for low- and intermediate-temperature operation

    Science.gov (United States)

    Smetana, Daryl L.; Carson, John C.

    1991-11-01

    The marriage of superconducting electronics with Z-plane FPA readout structures offer the potential for high speed, low power parallel digital processing on-focal plane. This paper reports on some early research into this marriage of two technologies conducted by Irvine Sensors Corporation (ISC) and TRW. Progress is reviewed for both low and high temperature superconducting technologies.

  5. CO tolerance by the PEMFC operational at temperatures up to 200°C

    DEFF Research Database (Denmark)

    Li, Qingfeng; He, Ronghuan; Gao, Ji-An;

    2003-01-01

    The CO poisoning effect on carbon-supported platinum catalysts in polymer electrolyte membrane fuel cells has been investigated in a temperature range from 125 to 200°C with the phosphoric acid-doped polybenzimidazole membranes as electrolyte. The effect is very temperature-dependent and can be s...... densities lower than 0.25 A/cm2. For comparison, the tolerance is only 0.0025 % CO (25 ppm) at 80°C at current densities up to 0.15 A/cm². The effect of CO2 in hydrogen was also studied. At 175°C, 25% CO2 in the fuel stream showed only the dilution effect.......The CO poisoning effect on carbon-supported platinum catalysts in polymer electrolyte membrane fuel cells has been investigated in a temperature range from 125 to 200°C with the phosphoric acid-doped polybenzimidazole membranes as electrolyte. The effect is very temperature-dependent and can...

  6. Operation experiences with a 30 kV/100 MVA high temperature superconducting cable system

    DEFF Research Database (Denmark)

    Tønnesen, Ole; Däumling, Manfred; Jensen, Kim Høj;

    2004-01-01

    of 1157 A. The operation experiences include over-currents of 6 kA due to faults on peripheral lines, commissioning, servicing and failure responses on the cooling system, continuous 24 h, 7 day per week monitoring and performance of the alarm system. The implications of these experiences for the future...

  7. A high-temperature gas-and-steam turbine plant operating on combined fuel

    Science.gov (United States)

    Klimenko, A. V.; Milman, O. O.; Shifrin, B. A.

    2015-11-01

    A high-temperature gas-steam turbine plant (GSTP) for ultrasupercritical steam conditions is proposed based on an analysis of prospects for the development of power engineering around the world and in Russia up to 2040. The performance indicators of a GSTP using steam from a coal-fired boiler with a temperature of 560-620°C with its superheating to 1000-1500°C by firing natural gas with oxygen in a mixingtype steam superheater are analyzed. The thermal process circuit and design of a GSTP for a capacity of 25 MW with the high- and intermediate-pressure high-temperature parts with the total efficiency equal to 51.7% and the natural gas utilization efficiency equal to 64-68% are developed. The principles of designing and the design arrangement of a 300 MW GSTP are developed. The effect of economic parameters (the level and ratio of prices for solid fuel and gas, and capital investments) on the net cost of electric energy is determined. The net cost of electric energy produced by the GSTP is lower than that produced by modern combined-cycle power plants in a wide variation range of these parameters. The components of a high-temperature GSTP the development of which determines the main features of such installations are pointed out: a chamber for combusting natural gas and oxygen in a mixture with steam, a vacuum device for condensing steam with a high content of nondensables, and a control system. The possibility of using domestically available gas turbine technologies for developing the GSTP's intermediate-pressure high-temperature part is pointed out. In regard of its environmental characteristics, the GSTP is more advantageous as compared with modern condensing power plants: it allows a flow of concentrated carbon dioxide to be obtained at its outlet, which can be reclaimed; in addition, this plant requires half as much consumption of fresh water.

  8. Study on wake structure characteristics of a slotted micro-ramp with large-eddy simulation

    Science.gov (United States)

    Dong, Xiangrui; Chen, Yaohui; Dong, Gang; Liu, Yixin

    2017-06-01

    In this paper, a novel slotted ramp-type micro vortex generator (slotted micro-ramp) for flow separation control is simulated in the supersonic flow of Ma = 1.5, based on large eddy simulation combined with the finite volume method. The wake structure characteristics and control mechanisms of both slotted and standard micro-ramps are presented and discussed. The results show that the wake of standard micro-ramp includes a primary counter-rotating streamwise vortex pair, a train of vortex rings, and secondary vortices. The slotted micro-ramp has more complicated wake structures, which contain a confluent counter-rotating streamwise vortex pair and additional streamwise vortices, with the same rotation generated by slot and the vortex rings enveloping the vortex pair. The additional vortices generated by the slot of the micro-ramp can mix with the primary counter-rotating vortex pair, extend the life time, and strengthen the vortex intensity of primary vortex pair. Moreover, the slot can effectively alleviate, or even eliminate the backflow and decrease the profile drag induced by the standard micro-ramp, therefore improving the efficiency of separation control.

  9. Observation of Solid-Solid Phase Transitions in Ramp-Compressed Aluminum

    Science.gov (United States)

    Polsin, D. N.; Boehly, T. R.; Delettrez, J. A.; Gregor, M. C.; McCoy, C. A.; Henderson, B.; Fratanduono, D. E.; Smith, R.; Kraus, R.; Eggert, J. H.; Collins, R.; Coppari, F.; Celliers, P. M.

    2016-10-01

    We present results of experiments using x-ray diffraction to study the crystalline structure of solid aluminum compressed up to 500 GPa. Aluminum is of interest because it is frequently used as a standard material in high-pressure compression experiments. At ambient pressure and temperature, Al is a face-centered cubic close-packed crystal and has been observed to transform to hexagonal close-packed (hcp) when compressed to 200GPa in a diamond anvil cell. It is predicted to transform from hcp to body-centered cubic when compressed to 315GPa. Laser-driven ramp waves will be used to compress Al to various constant-pressure states. The goal is to investigate the Al phase diagram along its isentrope, i.e., at temperatures 1000K and pressures ranging from 200 to 500 GPa. X-ray diffraction will be used to measure the crystalline structure of the compressed Al and observe the transformations that occur at various pressures. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  10. Deficiency of RAMP1 attenuates antigen-induced airway hyperresponsiveness in mice.

    Directory of Open Access Journals (Sweden)

    Manyu Li

    Full Text Available Asthma is a chronic inflammatory disease affecting the lung, characterized by breathing difficulty during an attack following exposure to an environmental trigger. Calcitonin gene-related peptide (CGRP is a neuropeptide that may have a pathological role in asthma. The CGRP receptor is comprised of two components, which include the G-protein coupled receptor, calcitonin receptor-like receptor (CLR, and receptor activity-modifying protein 1 (RAMP1. RAMPs, including RAMP1, mediate ligand specificity in addition to aiding in the localization of receptors to the cell surface. Since there has been some controversy regarding the effect of CGRP on asthma, we sought to determine the effect of CGRP signaling ablation in an animal model of asthma. Using gene-targeting techniques, we generated mice deficient for RAMP1 by excising exon 3. After determining that these mice are viable and overtly normal, we sensitized the animals to ovalbumin prior to assessing airway resistance and inflammation after methacholine challenge. We found that mice lacking RAMP1 had reduced airway resistance and inflammation compared to wildtype animals. Additionally, we found that a 50% reduction of CLR, the G-protein receptor component of the CGRP receptor, also ameliorated airway resistance and inflammation in this model of allergic asthma. Interestingly, the loss of CLR from the smooth muscle cells did not alter the airway resistance, indicating that CGRP does not act directly on the smooth muscle cells to drive airway hyperresponsiveness. Together, these data indicate that signaling through RAMP1 and CLR plays a role in mediating asthma pathology. Since RAMP1 and CLR interact to form a receptor for CGRP, our data indicate that aberrant CGRP signaling, perhaps on lung endothelial and inflammatory cells, contributes to asthma pathophysiology. Finally, since RAMP-receptor interfaces are pharmacologically tractable, it may be possible to develop compounds targeting the RAMP1/CLR

  11. RAMP1 suppresses mucosal injury from dextran sodium sulfate-induced colitis in mice.

    Science.gov (United States)

    Kawashima-Takeda, Noriko; Ito, Yoshiya; Nishizawa, Nobuyuki; Kawashima, Rei; Tanaka, Kiyoshi; Tsujikawa, Kazutake; Watanabe, Masahiko; Majima, Masataka

    2017-04-01

    Calcitonin gene-related peptide (CGRP) is thought to be involved in the modulation of intestinal motility. CGRP receptor is composed of receptor activity-modifying protein (RAMP) 1 combined with calcitonin receptor-like receptor (CRLR) for CGRP. The study investigated the role of CGRP in mice with experimentally induced colitis. The study used dextran sodium sulfate (DSS) to induce colitis in mice. The study compared the severity of colitis in wild-type (WT) mice, mice treated with a CGRP receptor antagonist (CGRP8-37 ), and RAMP1 knockout ((-/-) ) mice. Pathological changes in the mucosa were assessed, and inflammatory cells and cytokine levels were measured. The severity of inflammation in DSS-induced colitis increased markedly in CGRP8-37 -treated mice and RAMP1(-/-) mice compared with WT mice. RAMP1(-/-) mice showed more severe damage compared with CGRP8-37 -treated mice. The number of periodic acid-Schiff-positive cells decreased in CGRP8-37 -treated mice compared with WT mice and was even further decreased in RAMP1(-/-) mice. RAMP1 was expressed by macrophages, mast cells, and T-cells. RAMP1(-/-) mice exhibited excessive accumulation of macrophages and mast cells into the colonic tissue with increased levels of tumor necrosis factor-α and interleukin-1β as compared with WT mice. Infiltration of T-cells into the colonic mucosa, which was associated with the expression of T helper (Th) cytokines including Th1 (interferon gamma) and Th17 (IL-17), was augmented in RAMP1(-/-) mice. The findings of this study suggest that RAMP1 exerted mucosal protection in DSS-induced colitis via attenuation of recruitment of inflammatory cells and of pro-inflammatory cytokines. © 2016 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.

  12. Temperature Effects of Point Sources, Riparian Shading, and Dam Operations on the Willamette River, Oregon

    Science.gov (United States)

    Rounds, Stewart A.

    2007-01-01

    Water temperature is an important factor influencing the migration, rearing, and spawning of several important fish species in rivers of the Pacific Northwest. To protect these fish populations and to fulfill its responsibilities under the Federal Clean Water Act, the Oregon Department of Environmental Quality set a water temperature Total Maximum Daily Load (TMDL) in 2006 for the Willamette River and the lower reaches of its largest tributaries in northwestern Oregon. As a result, the thermal discharges of the largest point sources of heat to the Willamette River now are limited at certain times of the year, riparian vegetation has been targeted for restoration, and upstream dams are recognized as important influences on downstream temperatures. Many of the prescribed point-source heat-load allocations are sufficiently restrictive that management agencies may need to expend considerable resources to meet those allocations. Trading heat allocations among point-source dischargers may be a more economical and efficient means of meeting the cumulative point-source temperature limits set by the TMDL. The cumulative nature of these limits, however, precludes simple one-to-one trades of heat from one point source to another; a more detailed spatial analysis is needed. In this investigation, the flow and temperature models that formed the basis of the Willamette temperature TMDL were used to determine a spatially indexed 'heating signature' for each of the modeled point sources, and those signatures then were combined into a user-friendly, spreadsheet-based screening tool. The Willamette River Point-Source Heat-Trading Tool allows the user to increase or decrease the heating signature of each source and thereby evaluate the effects of a wide range of potential point-source heat trades. The predictions of the Trading Tool were verified by running the Willamette flow and temperature models under four different trading scenarios, and the predictions typically were accurate

  13. Performance of MWIR and SWIR HgCdTe-based focal plane arrays at high operating temperatures

    Science.gov (United States)

    Melkonian, Leon; Bangs, James; Elizondo, Lee; Ramey, Ron; Guerrero, Ernesto

    2010-04-01

    Raytheon Vision Systems (RVS) is producing large format, high definition HgCdTe-based MWIR and SWIR focal plane arrays (FPAs) with pitches of 15 μm and smaller for various applications. Infrared sensors fabricated from HgCdTe have several advantages when compared to those fabricated from other materials -- such as a highly tunable bandgap, high quantum efficiencies, and R0A approaching theoretical limits. It is desirable to operate infrared sensors at elevated operating temperatures in order to increase the cooler life and reduce the required system power. However, the sensitivity of many infrared sensors, including those made from HgCdTe, declines significantly above a certain temperature due to the noise resulting from increasing detector dark current. In this paper we provide performance data on a MWIR and a SWIR focal plane array operating at temperatures up to 160K and 170K, respectively. The FPAs used in the study were grown by molecular beam epitaxy (MBE) on silicon substrates, processed into a 1536x1024 format with a 15 μm pixel pitch, and hybridized to a silicon readout integrated circuit (ROIC) via indium bumps to form a sensor chip assembly (SCA). This data shows that the noise equivalent delta temperature (NEDT) is background limited at f/3.4 in the SWIR SCA (cutoff wavelength of 3.7 μm at 130K) up to 140K and in the MWIR SCA (cutoff wavelength of 4.8 μm at 115K) up to 115K.

  14. Single Temperature Liquefaction process at different operating pHs to improve ethanol production from Indian rice and corn feedstock.

    Science.gov (United States)

    Gohel, V; Ranganathan, K; Duan, G

    2016-10-13

    Conventional grain ethanol manufacturing is a high-temperature energy-intensive process comprising of multiple-unit operations when combined with lower ethanol recovery results in higher production cost. In liquefaction, jet cooking accounts for significant energy cost, while strong acid or base used for pH adjustment presents a safety hazard. A need is felt for sustainable ethanol manufacturing process that is less hazardous, consumes lower energy, and operates in a low pH range of 4.50-5.50. A single temperature liquefaction (STL) process that could efficiently operate at lower liquefaction temperature over a pH range of 4.50-5.50 was developed using rice and corn feedstock. Ethanol recovery witnessed at pH 4.5, 5.0, and 5.5 are 481.2 ± 1.5, 492.4 ± 1.5, and 493.6 ± 1.5 L MT(-1) rice, respectively. Similarly, ethanol recovery witnessed at pH 4.5, 5.0, and 5.5 are 404.6 ± 1.3, 413.9 ± 0.8, and 412.4 ± 1.8 L MT(-1) corn, respectively. The improvement in ethanol recovery is attributed to higher starch conversion by alpha-amylase even at pH as low as 4.50. Thus, the STL process operated at pH lower than 5.20 is poised to enhance sustainability by offering dual advantage of energy as well as chemical saving.

  15. Lifetime improvement of sheathed thermocouples for use in high-temperature and thermal operations

    Science.gov (United States)

    McCulloch, R. W.; Clift, J. H.

    Premature failure of small-diameter, magnesium-oxide-insulated sheathed thermocouples occurred when they were placed within nuclear fuel rod simulators to measure high temperatures and to follow severe thermal transients encountered during simulation of nuclear accidents in Oak Ridge National Laboratory thermal-hydraulic test facilities. Investigation of thermally cycled thermocouples yielded three criteria for improvement of thermocouple lifetime: (1) reduction of oxygen impurities prior to and during their fabrication; (2) refinement of thermoelement grain size during their fabrication; and (3) elimination of prestrain prior to use above their recrystallization temperature. The first and third criteria were satisfied by improved techniques of thermocouple assembly and by a recovery anneal prior to thermocouple use.

  16. A Method for more specific Simulation of Operative Temperature in Thermal Analysis Programmes

    DEFF Research Database (Denmark)

    Christensen, Jørgen Erik

    2008-01-01

    and the relative air velocity. However, in many programs the model for calculating the mean radiant temperature has traditionally been based on the calculation of an area weighted mean value independently of the location in the room. In practice the location of the person in the room has a significant influence...... and inhomogeneous radiation plays an important role for the usability and functionality of the room. In order to calculate the mean radiant temperature as function of the person´s location in the room one needs to calculate the angular factor between the person and the surfaces. The angular factor between surfaces...... can easily be calculated; however the angular factor between a person and a surface cannot be found directly from a formula, but needs to be approximated in order to be used in computer simulations. The paper describes different kinds of validations that have been done to compare different models...

  17. SNOW TEMPERATURE MEASUREMENTS AT VOSTOK STATION FROM AN AUTONOMOUS RECORDING SYSTEM (TAUTO: PRELIMINARY RESULTS FROM THE FIRST YEAR OPERATION

    Directory of Open Access Journals (Sweden)

    E. Lefebvre

    2012-01-01

    Full Text Available Temperature gradients in the upper layers of the snow pack are of importance for studying the emissivity properties of the snow surface with respect to microwaves used in remote sensing as well as for the heat and mass transfer in snow thickness. Gradients drive the initial snow microstructure metamorphisms that probably influence the firn properties in regard to air molecules fractionation and the air bubble enclosure process at close-off depths. As a contribution to investigation of these problems and following J.-M. Barnola initiative, we developed an autonomous recording system to monitor the temperature of the upper layers of the snow pack. The instrument was built to be autonomous and to be continuously operating within environmental conditions of the Antarctic plateau and the polar night. The apparatus which monitors temperature from the first 10 mof snow by 15 sensors of a «temperature grape» was set at Vostok station during 55th Russian Antarctic Expedition within the frame of the French Russian collaboration (GDRI Vostok. From the available hourly measurements over the first year, we present preliminary results on the thermal diffusive properties of the snow pack as well as some character of the temperature variations on the Antarctic plateau.

  18. Efficient ceramic anodes infiltrated with binary and ternary electrocatalysts for SOFCs operating at low temperatures

    DEFF Research Database (Denmark)

    Abdul Jabbar, Mohammed Hussain; Høgh, Jens Valdemar Thorvald; Zhang, Wei

    2012-01-01

    Electrocatalyst precursor of various combinations: Pt, Ru, Pd, Ni and Gd-doped CeO2 (CGO) were infiltrated into a porous Sr0.94Ti0.9Nb0.1O3 (STN) backbone, to study the electrode performance of infiltrated ceramic anodes at low temperature ranges of 400–600 °C. The performance of the binary elect...

  19. Effect of Temperature Variation and Gas Composition on the Stability of the RPC Operation

    CERN Document Server

    Cwiok, M; Górski, M; Królikowski, J

    2002-01-01

    An Inverted Double Gap RPC made of bakelite of 5*10^9 Ohm*cm volume resistivity was tested at avalanche rates up to 1 kHz/cm^2/gap in the Gamma Irradiation Facility at CERN in 2001. The inner surfaces of the chamber electrodes were cladded using linseed oil varnish. Dependence of the intrinsic RPC noise and the stability of the gas gain on the gas temperature and the gas composition are discussed.

  20. Characteristic features of the operation of high-temperature heat pipes with a noncondesable gas

    Science.gov (United States)

    Tolubinskiy, V. I.; Shevchuk, Ye. N.

    1987-01-01

    The principal concepts related to the nature of the processes occurring in high-temperature heat pipes with a noncondensable gas are examined, and guidelines for the development of such heat pipes are presented. The discussion is illustrated by experimental results obtained for a horizontal sodium heat pipe (diameter, 18/1 mm; length, 710 mm). In particular, attention is given to the starting dynamics and mechanisms, the shape of the vapor-gas front, and the vapor-gas front velocity.

  1. Temperature Control and Noise Reduction in our Compact ADR System for TES Microcalorimeter Operation

    Science.gov (United States)

    Hishi, U.; Fujimoto, R.; Kamiya, K.; Kotake, M.; Ito, H.; Kaido, T.; Tanaka, K.; Hattori, K.

    2016-08-01

    We have been developing a compact adiabatic demagnetization refrigerator, keeping ground application and future missions in mind. A salt pill fabricated in-house, a superconducting magnet with a passive magnetic shield around it, and a mechanical heat switch are mounted in a dedicated helium cryostat. The detector stage temperature is regulated by PID control of the magnet current, with a dI/dt term added to compensate the temperature rise due to parasitic heat. The temperature fluctuation of the detector stage is 1-2 \\upmu Krms, and the hold time was extended by about 15 % thanks to the dI/dt term. Bundle shields of the harnesses between the cryostat and the analog electronics boxes were connected to the chassis at both ends, and the analog electronics boxes were grounded to the cryostat through the bundle shields. This reduced the readout noise to 16 pA/√{Hz} in the 10-60 kHz range. Using this system, an energy resolution of 3.8 ± 0.2 eV (FWHM) was achieved at 5.9 keV.

  2. Increased operational temperature of Cr2O3-based spintronic devices

    Science.gov (United States)

    Street, Michael; Echtenkamp, Will; Komesu, Takashi; Cao, Shi; Wang, Jian; Dowben, Peter; Binek, Christian

    Spintronic devices have been considered a promising path to revolutionizing the current data storage and memory technologies. This work is an effort to utilize voltage-controlled boundary magnetization of the magnetoelectric chromia (Cr2O3) to be implemented into a spintronic device. The electric switchable boundary magnetization of chromia can be used to voltage-control the magnetic states of an adjacent ferromagnetic layer. For this technique to be utilized in a spintronic device, the antiferromagnetic ordering temperature of chromia must be enhanced above the bulk value of TN = 307K. Previously, based on first principle calculations, boron doped chromia thin films were fabricated via pulsed laser deposition showing boundary magnetization at elevated temperatures. Measurements of the boundary magnetization were also corroborated by spin polarized inverse photoemission spectroscopy. Exchange bias of B-doped chromia was also investigated using magneto-optical Kerr effect, showing an increased blocking temperature from 307K. Further boundary magnetization measurements and spin polarized inverse photoemission measurements indicate the surface magnetization to an in-plane orientation from the standard perpendicular orientation. This project was supported by the SRC through CNFD, an SRC-NRI Center under Task ID (2398.001) and by C-SPIN, part of STARnet, sponsored by MARCO and DARPA (No. SRC 2381.001).

  3. Temperature-dependent spectroscopy and microchip laser operation of Nd:KGd(WO4)2

    Science.gov (United States)

    Loiko, P.; Yoon, S. J.; Serres, J. M.; Mateos, X.; Beecher, S. J.; Birch, R. B.; Savitski, V. G.; Kemp, A. J.; Yumashev, K.; Griebner, U.; Petrov, V.; Aguiló, M.; Díaz, F.; Mackenzie, J. I.

    2016-08-01

    High-resolution absorption and stimulated-emission cross-section spectra are presented for monoclinic Nd:KGd(WO4)2 (Nd:KGW) laser crystals in the temperature range 77-450 K. At room-temperature, the maximum stimulated emission cross-section is σSE = 21.4 × 10-20 cm2 at 1067.3 nm, for light polarization E || Nm. The lifetime of the 4F3/2 state of Nd3+ in KGW is practically temperature independent at 115 ± 5 μs. Measurement of the energy transfer upconversion parameter for a 3 at.% Nd:KGW crystal proved that this was significantly smaller than for alternative hosts, ∼2.5 × 10-17 cm3/s. When cut along the Ng optical indicatrix axis, the Nd:KGW crystal was configured as a microchip laser, generating ∼4 W of continuous-wave output at 1067 nm with a slope efficiency of 61% under diode-pumping. Using a highly-doped (10 at.%) Nd:KGW crystal, the slope efficiency reached 71% and 74% when pumped with a laser diode and a Ti:Sapphire laser, respectively. The concept of an ultrathin (250 μm) Nd:KGW microchip laser sandwiched between two synthetic diamond heat-spreaders is demonstrated.

  4. High temperature oxidation behavior of AISI 304L stainless steel-Effect of surface working operations

    Science.gov (United States)

    Ghosh, Swati; Kumar, M. Kiran; Kain, Vivekanand

    2013-01-01

    The oxidation behavior of grade 304L stainless steel (SS) subjected to different surface finishing (machining and grinding) operations was followed in situ by contact electric resistance (CER) and electrochemical impedance spectroscopy (EIS) measurements using controlled distance electrochemistry (CDE) technique in high purity water (conductivity electrochemical properties and distinct morphological features of the oxide layer as a result of surface working were attributed to the prevalence of heavily fragmented grain structure and presence of martensite.

  5. Comparator circuits with local ramp buffering for a column-parallel single slope ADC

    Energy Technology Data Exchange (ETDEWEB)

    Milkov, Mihail M.

    2016-04-26

    A comparator circuit suitable for use in a column-parallel single-slope analog-to-digital converter comprises a comparator, an input voltage sampling switch, a sampling capacitor arranged to store a voltage which varies with an input voltage when the sampling switch is closed, and a local ramp buffer arranged to buffer a global voltage ramp applied at an input. The comparator circuit is arranged such that its output toggles when the buffered global voltage ramp exceeds the stored voltage. Both DC- and AC-coupled comparator embodiments are disclosed.

  6. Aphotic zone carbonate production on a Miocene ramp, Central Apennines, Italy

    Science.gov (United States)

    Corda, Laura; Brandano, Marco

    2003-09-01

    The lower Miocene Latium-Abruzzi platform was a low-angle ramp that developed under tropical-to-subtropical conditions, but was dominated by bryomol and rhodalgal sediment associations. The Aquitanian to Serravallian sequence described here paraconformably overlies the Cretaceous limestones. It consists of a lowstand systems tract, a transgressive systems tract and a highstand systems tract. Based on facies analysis and on the light dependence of biotic associations, the ramp is divided into three parts: an inner ramp, a middle ramp and an outer ramp. The inner ramp facies are represented by a few metres of coral framestone, rhodolith floatstone-rudstone and balanid macroids floatstone without wave-related structures. The middle ramp consists of structureless bioclastic grainstone to packstone, floatstone and rudstone with rhodoliths and larger foraminifera. The outer ramp facies—proximal sector—are composed of crudely stratified bryozoan-dominated packstone to floatstone which extend over the whole platform. The outer ramp facies—intermediate sector—are represented by wackestone, packstone and rarely grainstone with foraminifera and echinoid fragments. The final depositional profile of the ramp was strongly influenced by the main organisms producing sediment. During the lowstand, the resulting profile is a ramp type. During the transgressive phase, the rapid spreading of the outer ramp facies belt, as a consequence of the enhanced productivity of the light-independent biota, is believed to be promoted by a change from oligotrophic to eutrophic conditions. Climate and/or tectonics are presumed to have played an important role in continental runoff and then in the nutrients delivery. During the highstand phase, the system returns to rates of production uniform throughout the platform. The high rates of carbonate production occurring in the aphotic zone are quite unusual in tropical settings and represent a provocative trend in apparent contrast with the

  7. Parametric study of single expansion ramp nozzles at subsonic/transonic speeds

    Science.gov (United States)

    Capone, F. J.; Re, R. J.; Bare, E. A.; Maclean, M. K.

    1987-01-01

    The Langley Research Center has conducted a parametric investigation to determine the aeropropulsive characteristics of single expansion ramp nozzles (SERN). The SERN is a nonaxisymmetric, variable-area, internal/external expansion exhaust nozzle. Internal nozzle parameters that were varied included upper ramp length, ramp chordal angle, lower flap length, flap angle and the axial and vertical locations of nozzle throat. Convergent-divergent and convergent nozzles were included in this investigation which was conducted in the Langley 16-Foot Transonic Tunnel at Mach numbers from 0.6 to 1.2 and at nozzle pressure ratios up to 12.0.

  8. Design modification for the modular helium reactor for higher temperature operation and reliability studies for nuclear hydrogen production processes

    Science.gov (United States)

    Reza, S. M. Mohsin

    Design options have been evaluated for the Modular Helium Reactor (MHR) for higher temperature operation. An alternative configuration for the MHR coolant inlet flow path is developed to reduce the peak vessel temperature (PVT). The coolant inlet path is shifted from the annular path between reactor core barrel and vessel wall through the permanent side reflector (PSR). The number and dimensions of coolant holes are varied to optimize the pressure drop, the inlet velocity, and the percentage of graphite removed from the PSR to create this inlet path. With the removal of ˜10% of the graphite from PSR the PVT is reduced from 541°C to 421°C. A new design for the graphite block core has been evaluated and optimized to reduce the inlet coolant temperature with the aim of further reduction of PVT. The dimensions and number of fuel rods and coolant holes, and the triangular pitch have been changed and optimized. Different packing fractions for the new core design have been used to conserve the number of fuel particles. Thermal properties for the fuel elements are calculated and incorporated into these analyses. The inlet temperature, mass flow and bypass flow are optimized to limit the peak fuel temperature (PFT) within an acceptable range. Using both of these modifications together, the PVT is reduced to ˜350°C while keeping the outlet temperature at 950°C and maintaining the PFT within acceptable limits. The vessel and fuel temperatures during low pressure conduction cooldown and high pressure conduction cooldown transients are found to be well below the design limits. The reliability and availability studies for coupled nuclear hydrogen production processes based on the sulfur iodine thermochemical process and high temperature electrolysis process have been accomplished. The fault tree models for both these processes are developed. Using information obtained on system configuration, component failure probability, component repair time and system operating modes

  9. Hot Corrosion Studies of HVOF-Sprayed Coating on T-91 Boiler Tube Steel at Different Operating Temperatures

    Science.gov (United States)

    Bhatia, Rakesh; Singh, Hazoor; Sidhu, Buta Singh

    2013-11-01

    The aim of the present work is to investigate the usefulness of high velocity oxy fuel-sprayed 75% Cr3C2-25% (Ni-20Cr) coating to control hot corrosion of T-91 boiler tube steel at different operating temperatures viz 550, 700, and 850 °C. The deposited coatings on the substrates exhibit nearly uniform, adherent and dense microstructure with porosity less than 2%. Thermogravimetry technique is used to study the high temperature hot corrosion behavior of uncoated and coated samples. The corrosion products of the coating on the substrate are analyzed by using XRD, SEM, and FE-SEM/EDAX to reveal their microstructural and compositional features for the corrosion mechanisms. It is found that the coated specimens have shown minimum weight gain at all the operating temperatures when compared with uncoated T-91 samples. Hence, coating is effective in decreasing the corrosion rate in the given molten salt environment. Oxides and spinels of nickel-chromium may be the reason for successful resistance against hot corrosion.

  10. High temperature electrolyte supported Ni-GDC/YSZ/LSM SOFC operation on two-stage Viking gasifier product gas

    DEFF Research Database (Denmark)

    Hofmann, P.; Schweiger, A.; Fryda, L.

    2007-01-01

    This paper presents the results from a 150 h test of a commercial high temperature single planar solid oxide fuel cell (SOFC) operating on wood gas from the Viking two-stage fixed-bed downdraft gasifier, which produces an almost tar-free gas, that was further cleaned for particulates, sulphur...... at the SOFC operating temperature T = 850 degrees C. The cell operated with a fuel utilisation factor (U-f) around 30% and a current density of 260 mA cm(-2) resulting in an average power density of 207 mW cm(-2). Throughout the duration of the test, only a minor cell overpotential increase of 10 m......V was observed. Nevertheless, the V-j (voltage-current density) curves on H-2/N-2 before and after the wood gas test proved identical. Extensive SEM/EDS examination of the cell's anode showed that there was neither carbon deposition nor significant shifts in the anode microstructure or contamination when...

  11. High temperature electrolyte supported Ni-GDC/YSZ/LSM SOFC operation on two-stage Viking gasifier product gas

    Science.gov (United States)

    Hofmann, Ph.; Schweiger, A.; Fryda, L.; Panopoulos, K. D.; Hohenwarter, U.; Bentzen, J. D.; Ouweltjes, J. P.; Ahrenfeldt, J.; Henriksen, U.; Kakaras, E.

    This paper presents the results from a 150 h test of a commercial high temperature single planar solid oxide fuel cell (SOFC) operating on wood gas from the Viking two-stage fixed-bed downdraft gasifier, which produces an almost tar-free gas, that was further cleaned for particulates, sulphur and tar traces. The chosen SOFC was electrolyte supported with a nickel/gadolinium-doped cerium oxide (Ni-GDC) anode, known for its carbon deposition resistance. Through humidification the steam to carbon ratio (S/C) was adjusted to 0.5, which results in a thermodynamically carbon free condition at the SOFC operating temperature T = 850 °C. The cell operated with a fuel utilisation factor (U f) around 30% and a current density of 260 mA cm -2 resulting in an average power density of 207 mW cm -2. Throughout the duration of the test, only a minor cell overpotential increase of 10 mV was observed. Nevertheless, the V- j (voltage-current density) curves on H 2/N 2 before and after the wood gas test proved identical. Extensive SEM/EDS examination of the cell's anode showed that there was neither carbon deposition nor significant shifts in the anode microstructure or contamination when compared to an identical cell tested on H 2/N 2 only.

  12. Micro-Ramps for External Compression Low-Boom Inlets

    Science.gov (United States)

    Rybalko, Michael; Loth, Eric; Chima, Rodrick V.; Hirt, Stefanie M.; DeBonis, James R.

    2010-01-01

    The application of vortex generators for flow control in an external compression, axisymmetric, low-boom concept inlet was investigated using RANS simulations with three-dimensional (3-D), structured, chimera (overset) grids and the WIND-US code. The low-boom inlet design is based on previous scale model 1- by 1-ft wind tunnel tests and features a zero-angle cowl and relaxed isentropic compression centerbody spike, resulting in defocused oblique shocks and a weak terminating normal shock. Validation of the methodology was first performed for micro-ramps in supersonic flow on a flat plate with and without oblique shocks. For the inlet configuration, simulations with several types of vortex generators were conducted for positions both upstream and downstream of the terminating normal shock. The performance parameters included incompressible axisymmetric shape factor, separation area, inlet pressure recovery, and massflow ratio. The design of experiments (DOE) methodology was used to select device size and location, analyze the resulting data, and determine the optimal choice of device geometry. The optimum upstream configuration was found to substantially reduce the post-shock separation area but did not significantly impact recovery at the aerodynamic interface plane (AIP). Downstream device placement allowed for fuller boundary layer velocity profiles and reduced distortion. This resulted in an improved pressure recovery and massflow ratio at the AIP compared to the baseline solid-wall configuration.

  13. SOUTH RAMP 3.01.X AREA GROUND SUPPORT ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    S. Bonabian

    1999-07-12

    The purpose of this analysis is to evaluate the stability and determine ground support requirements for the 3.01.X areas in the Exploratory Studies Facility (ESF) South Ramp. The 3.01.X area refers to the ESF tunnel portions that were constructed under Section 3.01.X of the ESF General Construction Specification (Reference 8.4). Four 3.01.X areas in the ESF Main Loop are covered in this analysis that extend from Station 60+15.28 to 60+49.22, 62+04.82 to 62+32.77, 75+21.02 to 75+28.38, and 76+63.08 to 77+41.23. The scope of the analysis is (1) to document the as-built configuration including existing voids and installed ground support, (2) to evaluate the existing ground conditions, (3) to determine applicable design loads, (4) to evaluate the stability and determine a ground support system, and (5) to analyze the recommended system.

  14. On-chip micro-supercapacitors for operation in a wide temperature range

    OpenAIRE

    2013-01-01

    International audience; Onion-like carbon (OLC) based micro-supercapacitor electrodes prepared by electrophoretic deposition (EPD) were combined with a eutectic mixture of ionic liquids (IL), producing a micro-supercapacitor which is able to function from −50 °C to 80 °C. This device was electrochemically characterized by cyclic voltammetry and electrochemical impedance spectroscopy at different scan rates and different temperatures. At 20 °C, a capacitance of 1.1 mF.cm−2 per footprint area o...

  15. Operation of the Airmodus A11 nano Condensation Nucleus Counter at various inlet pressures and various operation temperatures, and design of a new inlet system

    Science.gov (United States)

    Kangasluoma, Juha; Franchin, Alessandro; Duplissy, Jonahtan; Ahonen, Lauri; Korhonen, Frans; Attoui, Michel; Mikkilä, Jyri; Lehtipalo, Katrianne; Vanhanen, Joonas; Kulmala, Markku; Petäjä, Tuukka

    2016-07-01

    Measuring sub-3 nm particles outside of controlled laboratory conditions is a challenging task, as many of the instruments are operated at their limits and are subject to changing ambient conditions. In this study, we advance the current understanding of the operation of the Airmodus A11 nano Condensation Nucleus Counter (nCNC), which consists of an A10 Particle Size Magnifier (PSM) and an A20 Condensation Particle Counter (CPC). The effect of the inlet line pressure on the measured particle concentration was measured, and two separate regions inside the A10, where supersaturation of working fluid can take place, were identified. The possibility of varying the lower cut-off diameter of the nCNC was investigated; by scanning the growth tube temperature, the range of the lower cut-off was extended from 1-2.5 to 1-6 nm. Here we present a new inlet system, which allows automated measurement of the background concentration of homogeneously nucleated droplets, minimizes the diffusion losses in the sampling line and is equipped with an electrostatic filter to remove ions smaller than approximately 4.5 nm. Finally, our view of the guidelines for the optimal use of the Airmodus nCNC is provided.

  16. A combined experimental and numerical approach for the control and monitoring of the SPES target during operation at high temperature

    Science.gov (United States)

    Ballan, Michele; Manzolaro, Mattia; Meneghetti, Giovanni; Andrighetto, Alberto; Monetti, Alberto; Bisoffi, Giovanni; Prete, Gianfranco

    2016-06-01

    The SPES project at INFN-LNL aims at the production of neutron-rich Radioactive Ion Beams (RIBs) using the ISOL (Isotope Separation On Line) technique. A 40 MeV 200 μA proton beam will directly impinge a uranium carbide target, generating approximately 1013 fissions per second. The target system is installed under vacuum inside a water-cooled chamber, and have to maintain high working temperatures, close to 2000 °C. During operation the proton beam provides the heating power required to keep the target at the desired temperature level. As a consequence, its characteristics have to be strictly controlled in order to avoid undesired overheating. According to the original design of the control system, the proton beam can be suddenly interrupted in case of out of range vacuum or cooling water flow levels. With the aim to improve the reliability of the control system a set of temperature sensors has been installed close to the target. Their types and installation positions were defined taking into consideration the detailed information coming from a dedicated thermal-electric model that allowed to investigate the most critical and inaccessible target hot-spots. This work is focused on the definition and experimental validation of the aforementioned numerical model. Its results were used to appropriately install two type C thermocouples, a PT100 thermo-resistance and a residual primary beam current detector. In addition the numerical model will be used for the definition of appropriate thresholds for each installed temperature sensor, since it allows to define a relationship between the locally measured values with the overall calculated temperature field. In case of over temperatures the monitoring system will send warning signals or in case interrupt the proton beam.

  17. Effects of temperature and operation parameters on the galvanic corrosion of Cu coupled to Au in organic solderability preservatives process

    Science.gov (United States)

    Oh, SeKwon; Kim, YoungJun; Jung, KiMin; Kim, JongSoo; Shon, MinYoung; Kwon, HyukSang

    2017-03-01

    In this work, we quantitatively examined the effects of temperature and operation parameters such as anode (Cu) to cathode (Au) area ratio, stirring speed, and Cu ion concentration on the galvanic corrosion kinetics of Cu coupled to Au (icouple ( Cu-Au)) on print circuit board in organic solderability preservative (OSP) soft etching solution. With the increase of temperature, galvanic corrosion rate (icouple ( Cu-Au) was increased; however, the degree of galvanic corrosion rate (icouple ( Cu-Au) - icorr (Cu)) was decreased owing to the lower activation energy of Cu coupled to Au, than that of Cu alone. With the increase of area ratio (cathode/anode), stirring speed of the system, icouple ( Cu-Au) was increased by the increase of cathodic reaction kinetics. And icouple ( Cu-Au) was decreased by the increase of the Cu-ion concentration in the OSP soft etching solution.

  18. Effects of temperature and operation parameters on the galvanic corrosion of Cu coupled to Au in organic solderability preservatives process

    Science.gov (United States)

    Oh, SeKwon; Kim, YoungJun; Jung, KiMin; Kim, JongSoo; Shon, MinYoung; Kwon, HyukSang

    2017-02-01

    In this work, we quantitatively examined the effects of temperature and operation parameters such as anode (Cu) to cathode (Au) area ratio, stirring speed, and Cu ion concentration on the galvanic corrosion kinetics of Cu coupled to Au (icouple (Cu-Au)) on print circuit board in organic solderability preservative (OSP) soft etching solution. With the increase of temperature, galvanic corrosion rate (icouple (Cu-Au) was increased; however, the degree of galvanic corrosion rate (icouple (Cu-Au) - icorr (Cu)) was decreased owing to the lower activation energy of Cu coupled to Au, than that of Cu alone. With the increase of area ratio (cathode/anode), stirring speed of the system, icouple (Cu-Au) was increased by the increase of cathodic reaction kinetics. And icouple (Cu-Au) was decreased by the increase of the Cu-ion concentration in the OSP soft etching solution.

  19. Assessment of body mapping sportswear using a manikin operated in constant temperature mode and thermoregulatory model control mode.

    Science.gov (United States)

    Wang, Faming; Del Ferraro, Simona; Molinaro, Vincenzo; Morrissey, Matthew; Rossi, René

    2014-09-01

    Regional sweating patterns and body surface temperature differences exist between genders. Traditional sportswear made from one material and/or one fabric structure has a limited ability to provide athletes sufficient local wear comfort. Body mapping sportswear consists of one piece of multiple knit structure fabric or of different fabric pieces that may provide athletes better wear comfort. In this study, the 'modular' body mapping sportswear was designed and subsequently assessed on a 'Newton' type sweating manikin that operated in both constant temperature mode and thermophysiological model control mode. The performance of the modular body mapping sportswear kit and commercial products were also compared. The results demonstrated that such a modular body mapping sportswear kit can meet multiple wear/thermal comfort requirements in various environmental conditions. All body mapping clothing (BMC) presented limited global thermophysiological benefits for the wearers. Nevertheless, BMC showed evident improvements in adjusting local body heat exchanges and local thermal sensations.

  20. Detection of H2S gas at lower operating temperature using sprayed nanostructured In2O3 thin films

    Indian Academy of Sciences (India)

    Ramesh H Bari; Parag P Patil; Sharad B Patil; Anil R Bari

    2013-11-01

    Nanostructured indium oxide (In2O3) thin films were prepared by spray pyrolysis (SP) technique. X-ray diffraction (XRD) was used to investigate the structural properties and field emission scanning electron microscopy (FESEM) was used to confirm surface morphology of In2O3 films. Measurement of electrical conductivity and gas sensing performance were conducted using static gas sensing system. Gas sensing performance was studied at different operating temperature in the range of 25–150°C for the gas concentration of 500 ppm. Themaximum sensitivity ( = 79%) to H2S was found at lower temperature of 50 °C. The quick response (4 s) and fast recovery (8 s) are the main features of this film.

  1. Eigenvalue distribution of the Dirac operator at finite temperature with (2+1)-flavor dynamical quarks using the HISQ action

    CERN Document Server

    Ohno, H; Karsch, F; Mukherjee, S

    2011-01-01

    We report on the behavior of the eigenvalue distribution of the Dirac operator in (2+1)-flavor QCD at finite temperature, using the HISQ action. We calculate the eigenvalue density at several values of the temperature close to the pseudocritical temperature. For this study we use gauge field configurations generated on lattices of size $32^3 \\times 8$ with two light quark masses corresponding to pion masses of about 160 and 115 MeV. We find that the eigenvalue density below $T_c$ receives large contributions from near-zero modes which become smaller as the temperature increases or the light quark mass decreases. Moreover we find no clear evidence for a gap in the eigenvalue density up to 1.1$T_c$. We also analyze the eigenvalue density near $T_c$ where it appears to show a power-law behavior consistent with what is expected in the critical region near the second order chiral symmetry restoring phase transition in the massless limit.

  2. Evaluation of a ZrO2 composite membrane in PEM fuel operating at high temperature and low relativity humidity

    Energy Technology Data Exchange (ETDEWEB)

    Guzman, C.; Alvarez, A.; Godinez, Luis A.; Herrera, O.E.; Merida, W.; Ledesma-Garcia, J.; Arriaga, L.G.

    2011-01-15

    Using proton exchange fuel cells (PEMFC's) is a sustainable way to generate electrical power. High temperature PEMFC's (HT - PEMFC's) have enhanced electrode kinetics, increased CO tolerance and simplified water management that these operation conditions imply. Unfortunately, Nafion and other perfluorosulfonic acid membranes (PFSA) are characterized by a decreased proton conductivity at high temperatures (above 100 degree C) due to dehydration which also causes shrinkage and increases the contact resistance between the membrane and the electrode. For these reasons, fuel cell research aims to create new membranes capable of working at high temperatures and low relative humidity conditions. The inclusion of inorganic materials into the Nafion matrix are employed to improve the mechanical properties of the membrane and enhance the membrane's hydration. In this study, the composite membrane ZrO2 showed better performance at high temperature and low relative humidity than commercial Nafion membrane. The performance results confirmed that composite membranes retain water and help retain the membrane hydration.

  3. Simulating potential structural and operational changes for Detroit Dam on the North Santiam River, Oregon, for downstream temperature management

    Science.gov (United States)

    Buccola, Norman L.; Rounds, Stewart A.; Sullivan, Annett B.; Risley, John C.

    2012-01-01

    Detroit Dam was constructed in 1953 on the North Santiam River in western Oregon and resulted in the formation of Detroit Lake. With a full-pool storage volume of 455,100 acre-feet and a dam height of 463 feet, Detroit Lake is one of the largest and most important reservoirs in the Willamette River basin in terms of power generation, recreation, and water storage and releases. The U.S. Army Corps of Engineers operates Detroit Dam as part of a system of 13 reservoirs in the Willamette Project to meet multiple goals, which include flood-damage protection, power generation, downstream navigation, recreation, and irrigation. A distinct cycle in water temperature occurs in Detroit Lake as spring and summer heating through solar radiation creates a warm layer of water near the surface and isolates cold water below. Controlling the temperature of releases from Detroit Dam, therefore, is highly dependent on the location, characteristics, and usage of the dam's outlet structures. Prior to operational changes in 2007, Detroit Dam had a well-documented effect on downstream water temperature that was problematic for endangered salmonid fish species, releasing water that was too cold in midsummer and too warm in autumn. This unnatural seasonal temperature pattern caused problems in the timing of fish migration, spawning, and emergence. In this study, an existing calibrated 2-dimensional hydrodynamic water-quality model [CE-QUAL-W2] of Detroit Lake was used to determine how changes in dam operation or changes to the structural release points of Detroit Dam might affect downstream water temperatures under a range of historical hydrologic and meteorological conditions. The results from a subset of the Detroit Lake model scenarios then were used as forcing conditions for downstream CE-QUAL-W2 models of Big Cliff Reservoir (the small reregulating reservoir just downstream of Detroit Dam) and the North Santiam and Santiam Rivers. Many combinations of environmental, operational, and

  4. Operative temperature and thermal comfort in the sun - Implementation and verification of a model for IDA ICE

    DEFF Research Database (Denmark)

    Karlsen, Line; Grozman, Grigori; Heiselberg, Per Kvols;

    2015-01-01

    (MRT) model for IDA Indoor Climate and Energy (IDA ICE). The new feature of the model is that it includes the effect of shortwave radiation in the room and contributes to a more comprehensive prediction of operative temperature, e.g. of a person exposed to direct sun light. The verification...... comfort of persons affected by direct solar radiation. This may further have implications on the predicted energy use and design of the façade, since e.g. an enlarged need for local cooling or use of dynamic solar shading might be discovered....

  5. Climatological attribution of wind power ramp events in East Japan and their probabilistic forecast based on multi-model ensembles downscaled by analog ensemble using self-organizing maps

    Science.gov (United States)

    Ohba, Masamichi; Nohara, Daisuke; Kadokura, Shinji

    2016-04-01

    Severe storms or other extreme weather events can interrupt the spin of wind turbines in large scale that cause unexpected "wind ramp events". In this study, we present an application of self-organizing maps (SOMs) for climatological attribution of the wind ramp events and their probabilistic prediction. The SOM is an automatic data-mining clustering technique, which allows us to summarize a high-dimensional data space in terms of a set of reference vectors. The SOM is applied to analyze and connect the relationship between atmospheric patterns over Japan and wind power generation. SOM is employed on sea level pressure derived from the JRA55 reanalysis over the target area (Tohoku region in Japan), whereby a two-dimensional lattice of weather patterns (WPs) classified during the 1977-2013 period is obtained. To compare with the atmospheric data, the long-term wind power generation is reconstructed by using a high-resolution surface observation network AMeDAS (Automated Meteorological Data Acquisition System) in Japan. Our analysis extracts seven typical WPs, which are linked to frequent occurrences of wind ramp events. Probabilistic forecasts to wind power generation and ramps are conducted by using the obtained SOM. The probability are derived from the multiple SOM lattices based on the matching of output from TIGGE multi-model global forecast to the WPs on the lattices. Since this method effectively takes care of the empirical uncertainties from the historical data, wind power generation and ramp is probabilistically forecasted from the forecasts of global models. The predictability skill of the forecasts for the wind power generation and ramp events show the relatively good skill score under the downscaling technique. It is expected that the results of this study provides better guidance to the user community and contribute to future development of system operation model for the transmission grid operator.

  6. Stability and scour development of bed material on crossbar block ramps

    Institute of Scientific and Technical Information of China (English)

    Mario OerteLa; DanieLB Bung

    2015-01-01

    Block ramps are ecologically oriented drop structures with adequate energy dissipation and partially moderate flow velocities. A special case is given with crossbar block ramps, where the upstream and downstream level difference is reduced by a series of basins. To prevent the total structure from failing, the stability of single boulders within the crossbars and the bed material in between must be guaranteed. The present paper addresses the stability of bed material and scour development for various flow regimes. Any bed material erosion may affect the stability of the crossbar boulders, which in turn can result in major damages of the ramp. Therefore new design approaches are developed to choose an appropriate bed material size and to avoid failures of crossbar block ramp structures.

  7. MEASURING CHROMATICITY ALONG THE RAMP USING THE PLL TUNE METER IN RHIC.

    Energy Technology Data Exchange (ETDEWEB)

    TEPIKIAN,S.; AHRENS,L.; CAMERON,P.; SCHULTHEISS,C.

    2002-06-02

    Beam stability up the ramp requires the appropriate sign and magnitude of the chromaticity. We developed a way to measure the chromaticity using the PLL (Phase Locked Loop) tune-meter. Since, the accuracy of the PLL tune-meter with properly adjusted loop gain is better than {approx} 0.0001 in tune units, the radial loop needs only be changed by a small amount of 0.2mm at a 1Hz rate. Thus, we can achieve fast chromaticity measurements in 1 sec. Except during the very beginning of the ramp where there are snapback effects and the gamma changes very rapidly, we can have good chromaticcity measurements along the ramp. This leads to the possibility of correcting the chromaticity during the ramp using a feedback system.

  8. Modelling ramp-up curves to reflect learning: improving capacity planning in secondary pharmaceutical production

    DEFF Research Database (Denmark)

    Hansen, Klaus Reinholdt Nyhuus; Grunow, Martin

    2015-01-01

    are overestimated. We develop a new method, which captures ramp-up as a function of the cumulative production volume to better reflect the experience gained while producing the new product. The use of the more accurate and computationally effective approach is demonstrated for the case of secondary pharmaceutical...... production. Due to its regulatory framework, this industry cannot fully exploit available capacities during ramp-up. We develop a capacity planning model for a new pharmaceutical drug, which determines the number and location of new production lines and the build-up of inventory such that product...... availability at market launch is ensured. Our MILP model is applied to a real industry case study using three empirically observed ramp-up curves to demonstrate its value as decision support tool. We demonstrate the superiority of our volume-dependent method over the traditional time-dependent ramp...

  9. Tamping Ramping: Algorithmic, Implementational, and Computational Explanations of Phasic Dopamine Signals in the Accumbens.

    Directory of Open Access Journals (Sweden)

    Kevin Lloyd

    2015-12-01

    Full Text Available Substantial evidence suggests that the phasic activity of dopamine neurons represents reinforcement learning's temporal difference prediction error. However, recent reports of ramp-like increases in dopamine concentration in the striatum when animals are about to act, or are about to reach rewards, appear to pose a challenge to established thinking. This is because the implied activity is persistently predictable by preceding stimuli, and so cannot arise as this sort of prediction error. Here, we explore three possible accounts of such ramping signals: (a the resolution of uncertainty about the timing of action; (b the direct influence of dopamine over mechanisms associated with making choices; and (c a new model of discounted vigour. Collectively, these suggest that dopamine ramps may be explained, with only minor disturbance, by standard theoretical ideas, though urgent questions remain regarding their proximal cause. We suggest experimental approaches to disentangling which of the proposed mechanisms are responsible for dopamine ramps.

  10. Optimizing density down-ramp injection for beam-driven plasma wakefield accelerators

    Science.gov (United States)

    Martinez de la Ossa, A.; Hu, Z.; Streeter, M. J. V.; Mehrling, T. J.; Kononenko, O.; Sheeran, B.; Osterhoff, J.

    2017-09-01

    Density down-ramp (DDR) injection is a promising concept in beam-driven plasma wakefield accelerators for the generation of high-quality witness beams. We review and complement the theoretical principles of the method and employ particle-in-cell (PIC) simulations in order to determine constrains on the geometry of the density ramp and the current of the drive beam, regarding the applicability of DDR injection. Furthermore, PIC simulations are utilized to find optimized conditions for the production of high-quality beams. We find and explain the intriguing result that the injection of an increased charge by means of a steepened ramp favors the generation of beams with lower emittance. Exploiting this fact enables the production of beams with high charge (˜140 pC ), low normalized emittance (˜200 nm ) and low uncorrelated energy spread (0.3%) in sufficiently steep ramps even for drive beams with moderate peak current (˜2.5 kA ).

  11. Synthesis and properties of aluminum-based composite materials for high operating temperatures

    Science.gov (United States)

    Vorozhtsov, Sergey; Khrustalyov, Anton; Kulkov, Sergey

    2016-11-01

    Aluminum-based composite materials reinforced with ceramic particles are of great practical interest due to their potentially high physical and mechanical properties. In this work, Al-Al4C3 composites are obtained by a hot-pressing method. Introduction of nanodiamonds into aluminum nanopowder in the amount 10 wt % leads to the formation of 15 wt % of aluminum carbide during hot pressing. It is found that composite materials with the diamond content of 10 wt % in the initial powder mixture have the microhardness 150 HV whilst the similarly hot-pressed aluminum powder without reinforcing particles shows a hardness of 75 HV. The mechanical properties of an Al-Al4C3 composite material at elevated test temperatures exceed those of commercial casting aluminum alloys.

  12. High efficiency linear compressor driven pulse tube cryocooler operating in liquid nitrogen temperature

    Institute of Scientific and Technical Information of China (English)

    HU JianYing; WANG XiaoTao; DAI Wei; LUO ErCang; HUANG Yu

    2009-01-01

    The inertance tube is one of the key components of a pulse tube cryocooler. It has great influence not only on the efficiency of the pulse tube cryocooler, but also on the efficiency of the linear compressor. Meanwhile, it is very difficult to predict the impedance of an inertance tube because of the turbulent flow. In this paper, using a quasi-turbulent model, the inertance tube is optimized to match a linear compressor driven pulse tube cryocooler. Experimental results show that this model can predict the impedance quite well. With 127 W input electric power, the pulse tube cryocooler obtains 9.4 W cooling power at a temperature of 77 K. The relative Carnot efficiency of the whole system reaches 19.8%.

  13. Silica based composite membranes for methanol fuel cells operating at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, A.; Guzman, C.; Peza-Ledesma, C.; Godinez, Luis A.; Nava, R.; Duron-Torres, S.M.; Ledesma-Garcia, J.; Arriaga, L.G.

    2011-01-15

    Direct methanol fuel cells (DMFCs) are seen as an alternative energy source for several applications, particularly portable power sources. Nafion membranes constitute a well known proton exchange system for DMFC systems due to their convenient electrochemical, mechanical and thermal stability and high proton conductivity properties. But there are problems currently associated with the direct methanol fuel cell technology. Intensive efforts to decrease the methanol crossover are focused mainly on the development of new polymer electrolyte membranes. In this study, Nafion polymer was modified by means of the incorporation of inorganic oxides with different structural properties (SBA-15 and SiO2), both prepared by sol-gel method in order to increase the proton conductivity at high temperature of fuel cell and to contribute decrementing the methanol crossover effect. Composite membranes based in inorganic fillers showed a significant decrease in the concentration of methanol permeation.

  14. Unraveling micro- and nanoscale degradation processes during operation of high-temperature polymer-electrolyte-membrane fuel cells

    Science.gov (United States)

    Hengge, K.; Heinzl, C.; Perchthaler, M.; Varley, D.; Lochner, T.; Scheu, C.

    2017-10-01

    The work in hand presents an electron microscopy based in-depth study of micro- and nanoscale degradation processes that take place during the operation of high-temperature polymer-electrolyte-membrane fuel cells (HT-PEMFCs). Carbon supported Pt particles were used as cathodic catalyst material and the bimetallic, carbon supported Pt/Ru system was applied as anode. As membrane, cross-linked polybenzimidazole was used. Scanning electron microscopy analysis of cross-sections of as-prepared and long-term operated membrane-electrode-assemblies revealed insight into micrometer scale degradation processes: operation-caused catalyst redistribution and thinning of the membrane and electrodes. Transmission electron microscopy investigations were performed to unravel the nanometer scale phenomena: a band of Pt and Pt/Ru nanoparticles was detected in the membrane adjacent to the cathode catalyst layer. Quantification of the elemental composition of several individual nanoparticles and the overall band area revealed that they stem from both anode and cathode catalyst layers. The results presented do not demonstrate any catastrophic failure but rather intermediate states during fuel cell operation and indications to proceed with targeted HT-PEMFC optimization.

  15. Degradation of H3PO4/PBI High Temperature Polymer Electrolyte Membrane Fuel Cell under Stressed Operating Conditions

    DEFF Research Database (Denmark)

    Zhou, Fan

    for HT-PEM fuel cell based micro-CHP units for households, the daily startup/shutdown operation is necessary. Moreover, the faults in the H2 supply system or in controlling the reformer can cause the H2 starvation of the HT-PEM fuel cell. The effects of these operating conditions to the degradation...... of the HT-PEM fuel cell are studied in the current work. Both in-situ and ex-situ characterization techniques are conducted to gain insight into the degradation mechanisms of the HT-PEM fuel cell under these operating conditions. The experimental results in this work suggest that the presence of methanol...... results in the degradation in cell performance of the HT-PEM fuel cell by increasing the charge transfer resistance and mass transfer resistance. The CO with volume fraction of 1% – 3% can cause significant performance loss to the HT-PEM fuel cell at the operating temperature of 150 oC. The cell...

  16. Evaluation of Fairchild's Gate Drive Optocoupler, Type FOD3150, Under Wide Temperature Operation

    Science.gov (United States)

    Patterson, Richard; Hammoud, Adhad; Panko, Scott

    2010-01-01

    An optocoupler is a semiconductor device that is used to transfer a signal between different parts of a circuit that need to be electrically isolated from one another - for example, where a high voltage is to be switched with a low voltage control signal. Optocouplers often can be used in place of relays. These optocouplers utilize an infrared LED (light emitting diode) and a photodetector such as a silicon controlled rectifier or photosensitive silicon diode for the transfer of the electronic signal between components of a circuit by means of a short optical transmission channel. For maximum coupling, the wave-length responses of the LED and the detector should be very similar. In switch-mode power supply applications, optocouplers offer advantages over transformers by virtue of simpler circuit design, reduced weight, and DC coupling capability. The effects of extreme temperature exposure and thermal cycling on the performance of a commercial-off-the-shelf (COTS) optocoupler, Fairchild FOD3150, were evaluated in this work. This 1.0 A output current, high noise immunity gate drive optocoupler utilizes an aluminum gallium arsenide (AlGaAs) LED, is capable of driving most 800V/20A IGBT/MOSFETs, and is suited for fast switching in motor control inverter applications and high performance power systems. Some of the specifications of the isolator chip are listed. The device was evaluated in terms of output response, output rise (t(sub r)) and fall times (t(sub f)), and propagation delays (using a 50% level between input and output during low to high (t(sub PLH)) and high to low (t(sub PLH)) transitions). The output supply current was also obtained. These parameters were recorded at various test temperatures between -190 C and +110 C.

  17. Properties of Phase Transition of Traffic Flow on Urban Expressway Systems with Ramps and Accessory Roads

    Institute of Scientific and Technical Information of China (English)

    梅超群; 刘业进

    2011-01-01

    In this paper, we develop a cellular automaton model to describe the phase transition of traffic flow on urban expressway systems with on-off-ramps and accessory roads. The lane changing rules are given in detailed, the numerical results show that the main road and the accessory road both produce phase transitions. These phase transitions will omen be influenced by the number of lanes, lane changing, the ramp flow, the input flow rate, and the geometry structure.

  18. Probabilistic Description of Traffic Breakdowns Caused by On-ramp Flow

    OpenAIRE

    Kuhne, Reinhart; Lubashevsky, Ihor; Mahnke, Reinhard; Kaupush, Jevgenijs

    2004-01-01

    The characteristic features of traffic breakdown near on-ramp are analyzed. To describe this phenomenon the probabilistic description regarding the jam emergence as the formation of a large car cluster on highway inside the synchronized traffic is constructed. In these terms the breakdown occurs through the formation of a certain critical nucleus in the metastable vehicle flow, which is located near the on-ramp. The strong cooperative car interaction in the synchronized traffic enables us to ...

  19. Downstream Effect of Ramping Neuronal Activity through Synapses with Short-Term Plasticity.

    Science.gov (United States)

    Wei, Wei; Wang, Xiao-Jing

    2016-04-01

    Ramping neuronal activity refers to spiking activity with a rate that increases quasi-linearly over time. It has been observed in multiple cortical areas and is correlated with evidence accumulation processes or timing. In this work, we investigated the downstream effect of ramping neuronal activity through synapses that display short-term facilitation (STF) or depression (STD). We obtained an analytical result for a synapse driven by deterministic linear ramping input that exhibits pure STF or STD and numerically investigated the general case when a synapse displays both STF and STD. We show that the analytical deterministic solution gives an accurate description of the averaging synaptic activation of many inputs converging onto a postsynaptic neuron, even when fluctuations in the ramping input are strong. Activation of a synapse with STF shows an initial cubical increase with time, followed by a linear ramping similar to a synapse without STF. Activation of a synapse with STD grows in time to a maximum before falling and reaching a plateau, and this steady state is independent of the slope of the ramping input. For a synapse displaying both STF and STD, an increase in the depression time constant from a value much smaller than the facilitation time constant τ(F) to a value much larger than τ(F) leads to a transition from facilitation dominance to depression dominance. Therefore, our work provides insights into the impact of ramping neuronal activity on downstream neurons through synapses that display short-term plasticity. In a perceptual decision-making process, ramping activity has been observed in the parietal and prefrontal cortices, with a slope that decreases with task difficulty. Our work predicts that neurons downstream from such a decision circuit could instead display a firing plateau independent of the task difficulty, provided that the synaptic connection is endowed with short-term depression.

  20. Particle Confinement Improvement with Current Ramp in the HL-IM Tokamak

    Institute of Scientific and Technical Information of China (English)

    YAN Long-Wen; WANG En-Yao; QIAN Jun; CHEN Liao-Yuan; LIU Yong

    2003-01-01

    Particle confinement with current ramp is investigated in the HL-IM tokamak. The ratio of particle confinement time to energy confinement time is used to determine confinement improvement. It increases a factor of 3 after the current rises twofold. An optimization density range to improve particle confinement is (1.5-3.5) XlO19 m~3. Particle confinement improvement during current ramp-up is beneficial to the startup of fusion reactors.

  1. Risk assessment in ramps for heavy vehicles--A French study.

    Science.gov (United States)

    Cerezo, Veronique; Conche, Florence

    2016-06-01

    This paper presents the results of a study dealing with the risk for heavy vehicles in ramps. Two approaches are used. On one hand, statistics are applied on several accidents databases to detect if ramps are more risky for heavy vehicles and to define a critical value for longitudinal slope. χ(2) test confirmed the risk in ramps and statistical analysis proved that a longitudinal slope superior to 3.2% represents a higher risk for heavy vehicles. On another hand, numerical simulations allow defining the speed profile in ramps for two types of heavy vehicles (tractor semi-trailer and 2-axles rigid body) and different loads. The simulations showed that heavy vehicles must drive more than 1000 m on ramps to reach their minimum speed. Moreover, when the slope is superior to 3.2%, tractor semi-trailer presents a strong decrease of their speed until 50 km/h. This situation represents a high risk of collision with other road users which drive at 80-90 km/h. Thus, both methods led to the determination of a risky configuration for heavy vehicles: ramps with a length superior to 1000 m and a slope superior to 3.2%. An application of this research work concerns design methods and guidelines. Indeed, this study provides threshold values than can be used by engineers to make mandatory specific planning like a lane for slow vehicles.

  2. Deformation in thrust-ramp anticlines and duplexes: implications for geometry and porosity

    Energy Technology Data Exchange (ETDEWEB)

    Groshong, R.H. Jr.; Usdansky, S.I.

    1986-05-01

    A computerized kinematic model of thrust-ramp anticline geometry allows workers to predict the zones of greatest deformation in ramp anticlines and fault duplexes. The model assumes a constant cross-section area, symmetrical fold hinges, and slip in the hanging wall parallel to the ramp and forelimb. Assuming that the collapse of original porosity or the generation of secondary fracture porosity is proportional to deformation, the model can be used to predict porosity changes. Deformation in a single ramp anticline is greatest in the forelimb and backlimb, and may be absent in the crest. A duplex structure results from comparatively closely spaced thrusts that have a common upper detachment horizon. Relatively wide spacing between the duplex faults yields a bumpy roofed duplex as in the central Appalachians. Forelimbs may be deformed twice and should show greater porosity modification. Relatively close spacing between ramp-and-flat thrusts can produce a listric-fault, snakehead anticline geometry because younger faults deform the preexisting thrust slices. The resulting geometry is here called a snakehead duplex and appears to be fairly common, as in the Jumpingpound field in the Canadian Rockies. Each thrust slice within the duplex is deformed six times or more, providing the maximum opportunity for deformation-related porosity changes. Maximum fracture porosity should occur in thrusts having listric-fan or snakehead duplex geometry. Structures involving duplexes generally should be better than isolated ramp anticlines.

  3. Cellular automata model simulating traffic car accidents in the on-ramp system

    Science.gov (United States)

    Echab, H.; Lakouari, N.; Ez-Zahraouy, H.; Benyoussef, A.

    2015-01-01

    In this paper, using Nagel-Schreckenberg model we study the on-ramp system under the expanded open boundary condition. The phase diagram of the two-lane on-ramp system is computed. It is found that the expanded left boundary insertion strategy enhances the flow in the on-ramp lane. Furthermore, we have studied the probability of the occurrence of car accidents. We distinguish two types of car accidents: the accident at the on-ramp site (Prc) and the rear-end accident in the main road (Pac). It is shown that car accidents at the on-ramp site are more likely to occur when traffic is free on road A. However, the rear-end accidents begin to occur above a critical injecting rate αc1. The influence of the on-ramp length (LB) and position (xC0) on the car accidents probabilities is studied. We found that large LB or xC0 causes an important decrease of the probability Prc. However, only large xC0 provokes an increase of the probability Pac. The effect of the stochastic randomization is also computed.

  4. Optimization of ramp area aircraft push back time windows in the presence of uncertainty

    Science.gov (United States)

    Coupe, William Jeremy

    It is well known that airport surface traffic congestion at major airports is responsible for increased taxi-out times, fuel burn and excess emissions and there is potential to mitigate these negative consequences through optimizing airport surface traffic operations. Due to a highly congested voice communication channel between pilots and air traffic controllers and a data communication channel that is used only for limited functions, one of the most viable near-term strategies for improvement of the surface traffic is issuing a push back advisory to each departing aircraft. This dissertation focuses on the optimization of a push back time window for each departing aircraft. The optimization takes into account both spatial and temporal uncertainties of ramp area aircraft trajectories. The uncertainties are described by a stochastic kinematic model of aircraft trajectories, which is used to infer distributions of combinations of push back times that lead to conflict among trajectories from different gates. The model is validated and the distributions are included in the push back time window optimization. Under the assumption of a fixed taxiway spot schedule, the computed push back time windows can be integrated with a higher level taxiway scheduler to optimize the flow of traffic from the gate to the departure runway queue. To enable real-time decision making the computational time of the push back time window optimization is critical and is analyzed throughout.

  5. LHC Report: Start of intensity ramp-up before a short breather

    CERN Multimedia

    Mike Lamont for the LHC team

    2015-01-01

    The first Stable Beams on 3 June were followed, to the accompaniment of thunderstorms, by the start of a phase known as the “intensity ramp-up” which saw the LHC team deliver physics with 50 bunches per beam. Time was also taken for a special five-day run devoted principally to the LHCf experiment. This week (15-19 June) the beam-based programme of the machine and its experiments was stopped temporarily for regular maintenance work.   LHCf’s Arm1 detector. While the first stable colliding beams were delivered with only 3 nominal bunches per beam, the aim of last week’s operations was to start the process of increasing the number of bunches in the beam with an ultimate 2015 target of ~2400 bunches per beam. The number of bunches is gradually increased in well-defined steps. At each step – 3 bunches per beam, then 13, 40 and, finally, 50 – the machine protection team requests 3 fills and around 20 hours of Stable Be...

  6. Lead iodide X-ray and gamma-ray spectrometers for room and high temperature operation

    Energy Technology Data Exchange (ETDEWEB)

    Hermon, H.; James, R.B.; Cross, E. [and others

    1997-02-01

    In this study, we report on the results of the investigation of lead iodide material properties. The effectiveness of zone refining purification methods on the material purity is determined by ICP-MS and ICP-OES and correlated to the electrical and physical material properties. We show that this zone refining method is very efficient in removing impurities from lead iodide and we also determine the segregation coefficient for some of these impurities. Triple axis x- ray diffraction (TAD) analysis has been used to determine the crystalline perfection of the lead iodide after applying various cutting, etching, and fabrication methods. The soft lead iodide crystal was found to be damaged when cleaved by a razor blade, but by using a diamond wheel saw, followed by etching, the crystallinity of the material was improved, as observed by TAD. Low temperature photoluminescence also indicates an improvement in the material properties of the purified lead iodide. Electrical properties of lead iodide such as carrier mobility, were calculated based on carrier- phonon scattering. The results for the electrical properties were in good agreement with the experimental data.

  7. Fluidized-bed denitrification for mine waters. Part I: low pH and temperature operation.

    Science.gov (United States)

    Papirio, S; Ylinen, A; Zou, G; Peltola, M; Esposito, G; Puhakka, J A

    2014-06-01

    Mining often leads to nitrate and metal contamination of groundwater and water bodies. Denitrification of acidic water was investigated in two up-flow fluidized-bed reactors (FBR) and using batch assays. Bacterial communities were enriched on ethanol plus nitrate in the FBRs. Initially, the effects of temperature, low-pH and ethanol/nitrate on denitrification were revealed. Batch assays showed that pH 4.8 was inhibitory to denitrification, whereas FBR characteristics permitted denitrification even at feed pH of 2.5 and at 7-8 °C. Nitrate and ethanol were removed and the feed pH was neutralized, provided that ethanol was supplied in excess to nitrate. Subsequently, Fe(II) and Cu impact on denitrification was investigated within batch tests at pH 7. Iron supplementation up to 100 mg/L resulted in iron oxidation and soluble concentrations ranging from 0.4 to 1.6 mg/L that stimulated denitrification. On the contrary, 0.7 mg/L of soluble Cu significantly slowed denitrification down resulting in about 45 % of inhibition in the first 8 h. Polymerase chain reaction-denaturant gradient gel electrophoresis demonstrated the co-existence of different denitrifying microbial consortia in FBRs. Dechloromonas denitrificans and Hydrogenophaga caeni were present in both FBRs and mainly responsible for nitrate reduction.

  8. Monolithically integrated mid-infrared sensor using narrow mode operation and temperature feedback

    Science.gov (United States)

    Ristanic, Daniela; Schwarz, Benedikt; Reininger, Peter; Detz, Hermann; Zederbauer, Tobias; Andrews, Aaron Maxwell; Schrenk, Werner; Strasser, Gottfried

    2015-01-01

    A method to improve the sensitivity and selectivity of a monolithically integrated mid-infrared sensor using a distributed feedback laser (DFB) is presented in this paper. The sensor is based on a quantum cascade laser/detector system built from the same epitaxial structure and with the same fabrication approach. The devices are connected via a dielectric-loaded surface plasmon polariton waveguide with a twofold function: it provides high light coupling efficiency and a strong interaction of the light with the environment (e.g., a surrounding fluid). The weakly coupled DFB quantum cascade laser emits narrow mode light with a FWHM of 2 cm-1 at 1586 cm-1. The room temperature laser threshold current density is 3 kA/cm2 and a pulsed output power of around 200 mW was measured. With the superior laser noise performance, due to narrow mode emission and the compensation of thermal fluctuations, the lower limit of detection was expanded by one order of magnitude to the 10 ppm range.

  9. New approach of gravity wave detection in mesopause temperatures operating an array of airglow spectrometers

    Science.gov (United States)

    Wachter, Paul; Schmidt, Carsten; Wüst, Sabine; Bittner, Michael

    2014-05-01

    GRIPS (Ground based Infrared P-branch Spectrometer) airglow measurements allow the derivation of kinetic temperature in the mesopause region averaged over a field of view of some 10km x 10km. In 2011, three identical GRIPS instruments were setup at Oberpfaffenhofen (11.28°E, 48.09°N), Germany, in a way that their fields of view form an equilateral triangle shape in the mesopause with a horizontal dimension of approximately 70km. Using this setup, GRIPS time series cannot only be analyzed with respect to gravity wave periods, but also spatial wave parameters can be derived. Based on the results of the harmonic analysis the horizontal wavelength, phase speed and the direction of propagation were determined for gravity wave events from February to July 2011. We present distinct relationships between periods, amplitudes, phase speeds and wavelengths, which were identified in this dataset. Further data analysis of the derived wave parameters show preferred directions of propagation and suggest seasonal variations of the wave characteristics. The presentation will be concluded by the introduction of a measurement setup relying on one GRIPS instrument which is equipped with a variably adjustable mirror optic. The capability to scan multiple fields of view during nightly measurements will offer longer-term investigations of mesopause gravity waves.

  10. Monolithically integrated mid-infrared sensor using narrow mode operation and temperature feedback

    Energy Technology Data Exchange (ETDEWEB)

    Ristanic, Daniela; Schwarz, Benedikt, E-mail: benedikt.schwarz@tuwien.ac.at; Reininger, Peter; Detz, Hermann; Zederbauer, Tobias; Andrews, Aaron Maxwell; Schrenk, Werner; Strasser, Gottfried [Institute for Solid State Electronics and Center for Micro- and Nanostructures, Vienna University of Technology, Floragasse 7, Vienna 1040 (Austria)

    2015-01-26

    A method to improve the sensitivity and selectivity of a monolithically integrated mid-infrared sensor using a distributed feedback laser (DFB) is presented in this paper. The sensor is based on a quantum cascade laser/detector system built from the same epitaxial structure and with the same fabrication approach. The devices are connected via a dielectric-loaded surface plasmon polariton waveguide with a twofold function: it provides high light coupling efficiency and a strong interaction of the light with the environment (e.g., a surrounding fluid). The weakly coupled DFB quantum cascade laser emits narrow mode light with a FWHM of 2 cm{sup −1} at 1586 cm{sup −1}. The room temperature laser threshold current density is 3 kA∕cm{sup 2} and a pulsed output power of around 200 mW was measured. With the superior laser noise performance, due to narrow mode emission and the compensation of thermal fluctuations, the lower limit of detection was expanded by one order of magnitude to the 10 ppm range.

  11. Propagation of Measurement-While-Drilling Mud Pulse during High Temperature Deep Well Drilling Operations

    Directory of Open Access Journals (Sweden)

    Hongtao Li

    2013-01-01

    Full Text Available Signal attenuates while Measurement-While-Drilling (MWD mud pulse is transmited in drill string during high temperature deep well drilling. In this work, an analytical model for the propagation of mud pulse was presented. The model consists of continuity, momentum, and state equations with analytical solutions based on the linear perturbation analysis. The model can predict the wave speed and attenuation coefficient of mud pulse. The calculated results were compared with the experimental data showing a good agreement. Effects of the angular frequency, static velocity, mud viscosity, and mud density behavior on speed and attenuation coefficients were included in this paper. Simulated results indicate that the effects of angular frequency, static velocity, and mud viscosity are important, and lower frequency, viscosity, and static velocity benefit the transmission of mud pulse. Influenced by density behavior, the speed and attenuation coefficients in drill string are seen to have different values with respect to well depth. For different circulation times, the profiles of speed and attenuation coefficients behave distinctly different especially in lower section. In general, the effects of variables above on speed are seen to be small in comparison.

  12. RHIC Polarized proton operation

    Energy Technology Data Exchange (ETDEWEB)

    Huang, H.; Ahrens, L.; Alekseev, I.G.; Aschenauer, E.; Atoian, G.; Bai, M.; Bazilevsky, A.; Blaskiewicz, M.; Brennan, J.M.; Brown, K.A.; Bruno, D.; Connolly, R.; Dion, A.; D' Ottavio, T.; Drees, K.A.; Fischer, W.; Gardner, C.; Glenn, J.W.; Gu, X.; Harvey, M.; Hayes, T.; Hoff, L.; Hulsart, R.L.; Laster, J.; Liu, C.; Luo, Y.; MacKay, W.W.; Makdisi, Y.; Marr, G.J.; Marusic, A.; Meot, F.; Mernick, K.; Michnoff, R,; Minty, M.; Montag, C.; Morris, J.; Nemesure, S.; Poblaguev, A.; Ptitsyn, V.; Ranjibar, V.; Robert-Demolaize, G.; Roser, T.; J.; Severino, F.; Schmidke, B.; Schoefer, V.; Severino, F.; Smirnov, D.; Smith, K.; Steski, D.; Svirida, D.; Tepikian, S.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J. Wang, G.; Wilinski, M.; Yip, K.; Zaltsman, A.; Zelenski, A.; Zeno, K.; Zhang, S.Y.

    2011-03-28

    The Relativistic Heavy Ion Collider (RHIC) operation as the polarized proton collider presents unique challenges since both luminosity(L) and spin polarization(P) are important. With longitudinally polarized beams at the experiments, the figure of merit is LP{sup 4}. A lot of upgrades and modifications have been made since last polarized proton operation. A 9 MHz rf system is installed to improve longitudinal match at injection and to increase luminosity. The beam dump was upgraded to increase bunch intensity. A vertical survey of RHIC was performed before the run to get better magnet alignment. The orbit control is also improved this year. Additional efforts are put in to improve source polarization and AGS polarization transfer efficiency. To preserve polarization on the ramp, a new working point is chosen such that the vertical tune is near a third order resonance. The overview of the changes and the operation results are presented in this paper. Siberian snakes are essential tools to preserve polarization when accelerating polarized beams to higher energy. At the same time, the higher order resonances still can cause polarization loss. As seen in RHIC, the betatron tune has to be carefully set and maintained on the ramp and during the store to avoid polarization loss. In addition, the orbit control is also critical to preserve polarization. The higher polarization during this run comes from several improvements over last run. First we have a much better orbit on the ramp. The orbit feedback brings down the vertical rms orbit error to 0.1mm, much better than the 0.5mm last run. With correct BPM offset and vertical realignment, this rms orbit error is indeed small. Second, the jump quads in the AGS improved input polarization for RHIC. Third, the vertical tune was pushed further away from 7/10 snake resonance. The tune feedback maintained the tune at the desired value through the ramp. To calibrate the analyzing power of RHIC polarimeters at any energy above

  13. Polymer Nanodot-Hybridized Alkyl Silicon Oxide Nanostructures for Organic Memory Transistors with Outstanding High-Temperature Operation Stability

    Science.gov (United States)

    Lee, Chulyeon; Seo, Jooyeok; Kim, Jeongnam; Jeong, Jaehoon; Han, Hyemi; Kim, Hwajeong; Kim, Youngkyoo

    2016-01-01

    Organic memory devices (OMDs) are becoming more important as a core component in flexible electronics era because of their huge potentials for ultrathin, lightweight and flexible plastic memory modules. In particular, transistor-type OMDs (TOMDs) have been gradually spotlighted due to their structural advantages possessing both memory and driving functions in single devices. Although a variety of TOMDs have been developed by introducing various materials, less attention has been paid to the stable operation at high temperatures. Here we demonstrate that the polymer nanodot-embedded alkyl silicon oxide (ASiO) hybrid materials, which are prepared by sol-gel and thermal cross-linking reactions between poly(4-vinylphenol) (PVP) and vinyltriethoxysilane, can deliver low-voltage (1~5 V) TOMDs with outstanding operation stability (>4700 cycles) at high temperatures (150 °C). The efficient low-voltage memory function is enabled by the embedded PVP nanodots with particular lattice nanostructures, while the high thermal stability is achieved by the cross-linked ASiO network structures. PMID:27703187

  14. Polymer Nanodot-Hybridized Alkyl Silicon Oxide Nanostructures for Organic Memory Transistors with Outstanding High-Temperature Operation Stability

    Science.gov (United States)

    Lee, Chulyeon; Seo, Jooyeok; Kim, Jeongnam; Jeong, Jaehoon; Han, Hyemi; Kim, Hwajeong; Kim, Youngkyoo

    2016-10-01

    Organic memory devices (OMDs) are becoming more important as a core component in flexible electronics era because of their huge potentials for ultrathin, lightweight and flexible plastic memory modules. In particular, transistor-type OMDs (TOMDs) have been gradually spotlighted due to their structural advantages possessing both memory and driving functions in single devices. Although a variety of TOMDs have been developed by introducing various materials, less attention has been paid to the stable operation at high temperatures. Here we demonstrate that the polymer nanodot-embedded alkyl silicon oxide (ASiO) hybrid materials, which are prepared by sol-gel and thermal cross-linking reactions between poly(4-vinylphenol) (PVP) and vinyltriethoxysilane, can deliver low-voltage (1~5 V) TOMDs with outstanding operation stability (>4700 cycles) at high temperatures (150 °C). The efficient low-voltage memory function is enabled by the embedded PVP nanodots with particular lattice nanostructures, while the high thermal stability is achieved by the cross-linked ASiO network structures.

  15. Methane gas sensing at relatively low operating temperature by hydrothermally prepared SnO{sub 2} nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Amutha, A. [Pondicherry University, Centre for Nanoscience and Technology (India); Amirthapandian, S. [Indira Gandhi Centre for Atomic Research, Materials Physics Division, Materials Science Group (India); Prasad, A. K. [Indira Gandhi Centre for Atomic Research, Surface and Nanoscience Division, Materials Science Group (India); Panigrahi, B. K. [Indira Gandhi Centre for Atomic Research, Materials Physics Division, Materials Science Group (India); Thangadurai, P., E-mail: thangadurai.p@gmail.com [Pondicherry University, Centre for Nanoscience and Technology (India)

    2015-07-15

    Tin oxide (SnO{sub 2}) nanorods were prepared by surfactant-free hydrothermal method and their methane gas sensing characteristics were studied. These SnO{sub 2} nanorods were characterized by XRD, SEM, TEM, EDS, EELS, UV–Visible, and Raman spectroscopies. The SnO{sub 2} nanorods were single crystalline possessing tetragonal rutile structure. Average diameter of the nanorods was in the range from 8 to 48 nm with an average length of 174 nm. The diameter of the nanorod was found to increase with the increase of reaction time. The E{sub g} and A{sub 1g} Raman modes showed a significant blue and red shift, respectively, and this was due to the contribution from the phonons with q ≠ 0 in the first Brillouin zone. Gas sensing measurements against methane gas showed a good sensitivity at an operating temperature of 100 °C, and the maximum gas sensitivity was observed at 175 °C. Our present experiments clearly demonstrate the sensitivity of methane up to 300 ppm at 100 °C, which is a lower operating temperature compared to the previously reported values. Hydrogen sensor was also fabricated with the same SnO{sub 2} nanorods and its performance was compared with the methane gas sensor. These rods show better sensitivity toward methane gas than hydrogen gas.

  16. Charge collection efficiency and resolution of an irradiated double sided silicon microstrip detector operated at cryogenic temperatures

    CERN Document Server

    Bartalini, P; Buytaert, J; Chabaud, V; Collins, P; Dijkstra, H; Dormond, O; Frei, R; Parkes, C; Ruf, T; Saladino, S; Saladino, Stefania

    1999-01-01

    99-026 This paper presents results on the measurement of the cluster shapes, resolution and charge collection efficiency of a double sided silicon microstrip detector after irradiation with 24 GeV protons to a fluence of 3.5 x 10^14 p/cm2 and operated at cryogenic temperatures. An empirical model is presented which describes the expected cluster shapes as a function of depletion depth, and is shown to agree with the data. It is observed that the clusters on the p-side broaden if the detector is under-depleted, leading to a degradation of resolution and efficiency.The model is used to make predictions for detector types envisaged for the LHC experiments. The results also show that at cryogenic temperature the charge collection efficiency varies depending on the operating conditions of the detector and can reach values of 100 % at unexpectedly low bias voltage. By analysing the cluster shapes it is shown that these variations are due to changes in depletion depth. This phenomenon, known as the ``Lazarus effect'...

  17. Modeling and Simulation of - and Silicon Germanium-Base Bipolar Transistors Operating at a Wide Range of Temperatures.

    Science.gov (United States)

    Shaheed, M. Reaz

    1995-01-01

    Higher speed at lower cost and at low power consumption is a driving force for today's semiconductor technology. Despite a substantial effort toward achieving this goal via alternative technologies such as III-V compounds, silicon technology still dominates mainstream electronics. Progress in silicon technology will continue for some time with continual scaling of device geometry. However, there are foreseeable limits on achievable device performance, reliability and scaling for room temperature technologies. Thus, reduced temperature operation is commonly viewed as a means for continuing the progress towards higher performance. Although silicon CMOS will be the first candidate for low temperature applications, bipolar devices will be used in a hybrid fashion, as line drivers or in limited critical path elements. Silicon -germanium-base bipolar transistors look especially attractive for low-temperature bipolar applications. At low temperatures, various new physical phenomena become important in determining device behavior. Carrier freeze-out effects which are negligible at room temperature, become of crucial importance for analyzing the low temperature device characteristics. The conventional Pearson-Bardeen model of activation energy, used for calculation of carrier freeze-out, is based on an incomplete picture of the physics that takes place and hence, leads to inaccurate results at low temperatures. Plasma -induced bandgap narrowing becomes more pronounced in device characteristics at low temperatures. Even with modern numerical simulators, this effect is not well modeled or simulated. In this dissertation, improved models for such physical phenomena are presented. For accurate simulation of carrier freeze-out, the Pearson-Bardeen model has been extended to include the temperature dependence of the activation energy. The extraction of the model is based on the rigorous, first-principle theoretical calculations available in the literature. The new model is shown

  18. Study on the reversible capacity loss of layered oxide cathode during low-temperature operation

    Science.gov (United States)

    Li, Yiyang; Qian, Kun; He, Yan-Bing; Kaneti, Yusuf Valentino; Liu, Dongqing; Luo, Dan; Li, Hai; Li, Baohua; Kang, Feiyu

    2017-02-01

    In this study, commercial Li(Ni1/3Co1/3Mn1/3)O2/graphite (NCM/C) lithium-ion batteries were cycled at -10 °C under different current rates ranging from 0.2 C to 1C. Electrochemical measurements and post-mortem analysis were performed to identify the root causes of the degradation in the electrochemical performance of the cells. The results reveal that apart from the increase of lithium plating on the anode, there is a considerable and abnormal capacity loss on the NCM cathode with the increase in current rate. The different degradation mechanisms including the loss of lithium inventory (LLI) and the specific capacity loss of NCM material (LAM) during cycling at -10 °C were analyzed quantitatively. It is shown that the evolution trend of LLI with the increase in current rate (8.6%, 35.0%, 55.8% for 0.2 C, 0.5 C and 1 C respectively) corresponds closely to that of the capacity loss of the full-cells (8.6%, 45.5%, 63.6% for 0.2 C, 0.5 C and 1 C, respectively), which is different to the trend of LAM (7.2%, 8.8%, 22.3% for 0.2 C, 0.5 C and 1 C, respectively). Further analysis by XRD and HR-TEM clearly indicates that the crystallinity of the hexagonal layered structure of NCM was greatly impaired after low-temperature cycling at -10 °C, and spinel phase can be observed among the layered structure.

  19. Stabilized composite membranes and membrane electrode assemblies for high temperature/low relative humidity polymer electrolyte fuel cell operation

    Science.gov (United States)

    Ramani, Vijay Krishna

    Polymer electrolyte membrane fuel cells (PEMFCs) have a variety of applications in the stationary power, mobile power and automotive power sectors. Existing membrane technology presently permits fuel cell operation at temperatures less than 100°C under fully saturated conditions. However, several advantages such as easier heat rejection rates and improved impurities tolerance by the anode electrocatalyst result by operating a PEMFC at elevated temperatures (above 100°C) and lower relative humidities. In an attempt to extend the operating range of the polymer electrolyte membrane, perfluorosulfonic acid (NafionRTM) based organic/inorganic (heteropolyacid) composite membranes were investigated in terms of thermal and electrochemical stability, additive stability and conductivity. Tungsten based heteropolyacids (HPAs) were found to be electrochemically stable as opposed to molybdenum based additives. The stability of the inorganic heteropolyacid additive in aqueous environments was enhanced by ion exchanging the protons of the HPAs with larger counter ions. An additional stabilization technique developed involved improving the interaction of HPA with NafionRTM by linking the particles to the sulfonic acid clusters via a sol-gel induced metal oxide linkage. The proton conductivity of the composite membranes was found to depend on the particle size of the HPA additive. A two order of magnitude change in additive particle size was attained by modification of the membrane preparation technique. This modification resulted in a nearly 50% increase in conductivity. The membranes prepared were characterized by thermal analysis, spectroscopy and microscopy. A technique was developed to incorporate existing MEA preparation and HPA stabilization techniques to the composite membranes with small HPA particles. All MEAs prepared were evaluated at high temperatures (120°C) and low relative humidities (35%) in an operating fuel cell, with membrane resistance and hence conductivity

  20. Enhancing nitrification at low temperature with zeolite in a mining operations retention pond

    Directory of Open Access Journals (Sweden)

    Misha eMiazga-Rodriguez

    2012-07-01

    Full Text Available Ammonium nitrate explosives are used in mining operations at Diavik Diamond Mines Inc. in the Northwest Territories, Canada. Residual nitrogen is washed into the mine pit and piped to a nearby retention pond where its removal is accomplished by microbial activity prior to a final water treatment step and release into the sub-Arctic lake, Lac de Gras. Microbial removal of ammonium in the retention pond is rapid during the brief ice-free summer, but often slows under ice cover that persists up to nine months of the year. The aluminosilicate mineral zeolite was tested as an additive to retention pond water to increase rates of ammonium removal at 4 °C. Water samples were collected across the length of the retention pond monthly over a year. The structure of the microbial community (bacteria, archaea, and eukarya, as determined by denaturing gradient gel electrophoresis of PCR-amplified small subunit ribosomal RNA genes, was more stable during cold months than during July-September, when there was a marked phytoplankton bloom. Of the ammonia-oxidizing community, only bacterial amoA genes were consistently detected. Zeolite (10 g was added to retention pond water (100 mL amended with 5 mM ammonium and incubated at 12 °C to encourage development of a nitrifying biofilm. The biofilm community was composed of different amoA phylotypes from those identified in gene clone libraries of native water samples. Zeolite biofilm was added to fresh water samples collected at different times of the year, resulting in a significant increase in laboratory measurements of potential nitrification activity at 4 °C. A significant positive correlation between the amount of zeolite biofilm and potential nitrification activity was observed; rates were unaffected in incubations containing 1-20 mM ammonium. Addition of zeolite to retention ponds in cold environments could effectively increase nitrification rates year round by concentrating active nitrifying biomass.

  1. Three-Dimensional Printable High-Temperature and High-Rate Heaters.

    Science.gov (United States)

    Yao, Yonggang; Fu, Kun Kelvin; Yan, Chaoyi; Dai, Jiaqi; Chen, Yanan; Wang, Yibo; Zhang, Bilun; Hitz, Emily; Hu, Liangbing

    2016-05-24

    High temperature heaters are ubiquitously used in materials synthesis and device processing. In this work, we developed three-dimensional (3D) printed reduced graphene oxide (RGO)-based heaters to function as high-performance thermal supply with high temperature and ultrafast heating rate. Compared with other heating sources, such as furnace, laser, and infrared radiation, the 3D printed heaters demonstrated in this work have the following distinct advantages: (1) the RGO based heater can operate at high temperature up to 3000 K because of using the high temperature-sustainable carbon material; (2) the heater temperature can be ramped up and down with extremely fast rates, up to ∼20 000 K/second; (3) heaters with different shapes can be directly printed with small sizes and onto different substrates to enable heating anywhere. The 3D printable RGO heaters can be applied to a wide range of nanomanufacturing when precise temperature control in time, placement, and the ramping rate are important.

  2. Room temperature CW and QCW operation of Ho:CaF2 laser pumped by Tm:fiber laser

    Science.gov (United States)

    Jelínek, Michal; Cvrček, Jan; Kubeček, Václav; Zhao, Beibei; Ma, Weiwei; Jiang, Dapeng; Su, Liangbi

    2017-05-01

    Laser radiation in the wavelength range around 2 μm is required for its specific properties - it is very suitable for medical applications, remote sensing, or pumping of optical parametric oscillators to generate ultrafast pulses in the mid-IR region further exploited in nonlinear optics. Crystals as YLF, YAG, LLF, and GdVO4 doped by holmium were already investigated and found suitable for the tunable laser generation around 2.1 mμ. Only a few works are devoted to the laser operation of holmium-doped fluorides as CaF2. In this work, pulsed and continuous-wave laser operation of a modified- Bridgman-grown Ho:CaF2 active crystal at room temperature is reported. A commercial 50 W 1940 nm Tm-fiber laser was used to pump a laser oscillator based on a novel 10 mm long 0.5 at.% Ho:CaF2 active crystal placed in the Peltiercooled holder. In the pulsed regime (10 ms, 10 Hz), the laser slope efficiency of 53 % with respect to the absorbed pump power was achieved. The laser generated at the central wavelength of 2085 nm with the maximum mean output power of 365 mW corresponding to the power amplitude of 3.65 W. In the continuous wave regime, the maximum output power was 1.11 W with the slope efficiency of 41 % with respect to the absorbed pump power. To our best knowledge this is the first demonstration of this laser active material operating in the CW regime at room temperature. The tuning range over 60 nm from 2034 to 2094 nm was achieved using a birefringent filter showing the possibility to develop a mode-locked laser system generating pulses in the sub-picosecond range.

  3. Nanostructured ZrO2 Thick Film Resistors as H2-Gas Sensors Operable at Room Temperature

    Directory of Open Access Journals (Sweden)

    K. M. GARADKAR

    2009-11-01

    Full Text Available Nanostructured ZrO2 powder was synthesized by microwave assisted sol-gel method. The material was characterized by XRD and SEM techniques. X-Ray diffraction studies confirm that a combination of tetragonal and monoclinic zirconia nanoparticles is obtained by using microwave-assisted method. The nanopowder was calcined at an optimized temperature of 400 °C for 3 h. The prepared powder had crystalline size about 25 nm. Thick films of synthesized ZrO2 powder were prepared by screen printing technique. The gas sensing performances of these films for various gases were tested. Films showed highest response to H2 (50 ppm gas at room temperature with poor responses to others (1000 ppm. The quick response and fast recovery are the main features of this sensor. The effects of microstructure, operating temperature and gas concentration on the gas response, selectivity, response time and recovery time of the sensor in the presence of H2 gas and others were studied and discussed.

  4. Development and Experimental Benchmark of Simulations to Predict Used Nuclear Fuel Cladding Temperatures during Drying and Transfer Operations

    Energy Technology Data Exchange (ETDEWEB)

    Greiner, Miles [Univ. of Nevada, Reno, NV (United States)

    2017-03-31

    Radial hydride formation in high-burnup used fuel cladding has the potential to radically reduce its ductility and suitability for long-term storage and eventual transport. To avoid this formation, the maximum post-reactor temperature must remain sufficiently low to limit the cladding hoop stress, and so that hydrogen from the existing circumferential hydrides will not dissolve and become available to re-precipitate into radial hydrides under the slow cooling conditions during drying, transfer and early dry-cask storage. The objective of this research is to develop and experimentallybenchmark computational fluid dynamics simulations of heat transfer in post-pool-storage drying operations, when high-burnup fuel cladding is likely to experience its highest temperature. These benchmarked tools can play a key role in evaluating dry cask storage systems for extended storage of high-burnup fuels and post-storage transportation, including fuel retrievability. The benchmarked tools will be used to aid the design of efficient drying processes, as well as estimate variations of surface temperatures as a means of inferring helium integrity inside the canister or cask. This work will be conducted effectively because the principal investigator has experience developing these types of simulations, and has constructed a test facility that can be used to benchmark them.

  5. Late Miocene breccia of Menorca (Balearic Islands) a basis for the interpretation of a Neogene ramp deposit

    Science.gov (United States)

    Obrador, A.; Pomar, L.; Taberner, C.

    1992-08-01

    Neogene (Tortonian) ramp facies associations crop out in the southern sector of Menorca (Balearic island). These are made mainly by sigmoidal and oblique clinoform units comprising rhodoliths, bryozoans, molluscs and foraminifera. These units are interpreted as outer-ramp deposits. A breccia deposit infilling an erosional surface is found at the top of the carbonate ramp sequence. The breccia components (mainly rhodoliths and oolite clasts) may represent erosion of the underlying ramp deposits and inner-ramp counterparts, which do not crop out on the island. The study of components in the breccia deposits confirms the indigenous character of the outer-ramp facies associations, which suggests that the ramp was steepened distally. The breccia deposits correspond laterally to a discontinuity surface locally showing karstic features. Transgressive sediments (including a phosphatic crust) are found above the discontinuity surface. All together these features, and the dolomitisation of the uppermost ramp sediments and breccia deposits, suggest that the breccia originated from erosion of the ramp after a major relative sea-level fall. The breccia and discontinuity surface separate the ramp sequence from an overlying prograding sequence. A correlation of this sequence boundary to other areas in the western Mediterranean is proposed.

  6. Rechargeable Lithium Sulfur (Li-S) Battery with Specific Energy 400 Wh/kg and Operating Temperature Range -60?C to 60?C Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Sion Power is developing a rechargeable lithium sulfur (Li-S) battery with a demonstrated specific energy exceeding 350 Wh/kg and the range of operating temperatures...

  7. Anatomy of a cyclically packaged Mesoproterozoic carbonate ramp in northern Canada

    Science.gov (United States)

    Sherman, A. G.; Narbonne, G. M.; James, N. P.

    2001-03-01

    Carbonates in the upper member of the Mesoproterozoic Victor Bay Formation are dominated by lime mud and packaged in cycles of 20-50 m. These thicknesses exceed those of classic shallowing-upward cycles by almost a factor of 10. Stratigraphic and sedimentological evidence suggests high-amplitude, high-frequency glacio-eustatic cyclicity, and thus a cool global climate ca. 1.2 Ga. The Victor Bay ramp is one of several late Proterozoic carbonate platforms where the proportions of lime mud, carbonate grains, and microbialites are more typical of younger Phanerozoic successions which followed the global waning of stromatolites. Facies distribution in the study area is compatible with deposition on a low-energy, microtidal, distally steepened ramp. Outer-ramp facies are hemipelagic lime mudstone, shale, carbonaceous rhythmite, and debrites. Mid-ramp facies are molar-tooth limestone tempestite with microspar-intraclast lags. In a marine environment where stromatolitic and oolitic facies were otherwise rare, large stromatolitic reefs developed at the mid-ramp, coeval with inner-ramp facies of microspar grainstone, intertidal dolomitic microbial laminite, and supratidal evaporitic red shale. Deep-subtidal, outer-ramp cycles occur in the southwestern part of the study area. Black dolomitic shale at the base is overlain by ribbon, nodular, and carbonaceous carbonate facies, all of which exhibit signs of synsedimentary disruption. Cycles in the northeast are shallow-subtidal and peritidal in character. Shallow-subtidal cycles consist of basal deep-water facies, and an upper layer of subtidal molar-tooth limestone tempestite interbedded with microspar calcarenite facies. Peritidal cycles are identical to shallow-subtidal cycles except that they contain a cap of dolomitic tidal-flat microbial laminite, and rarely of red shale sabkha facies or of sandy polymictic conglomerate. A transect along the wall of a valley extending 8.5 km perpendicular to depositional strike reveals

  8. Development of gas cooled reactors and experimental setup of high temperature helium loop for in-pile operation

    Energy Technology Data Exchange (ETDEWEB)

    Miletić, Marija, E-mail: marija_miletic@live.com [Czech Technical University in Prague, Prague (Czech Republic); Fukač, Rostislav, E-mail: fuk@cvrez.cz [Research Centre Rez Ltd., Rez (Czech Republic); Pioro, Igor, E-mail: Igor.Pioro@uoit.ca [University of Ontario Institute of Technology, Oshawa (Canada); Dragunov, Alexey, E-mail: Alexey.Dragunov@uoit.ca [University of Ontario Institute of Technology, Oshawa (Canada)

    2014-09-15

    Highlights: • Gas as a coolant in Gen-IV reactors, history and development. • Main physical parameters comparison of gas coolants: carbon dioxide, helium, hydrogen with water. • Forced convection in turbulent pipe flow. • Gas cooled fast reactor concept comparisons to very high temperature reactor concept. • High temperature helium loop: concept, development, mechanism, design and constraints. - Abstract: Rapidly increasing energy and electricity demands, global concerns over the climate changes and strong dependence on foreign fossil fuel supplies are powerfully influencing greater use of nuclear power. In order to establish the viability of next-generation reactor concepts to meet tomorrow's needs for clean and reliable energy production the fundamental research and development issues need to be addressed for the Generation-IV nuclear-energy systems. Generation-IV reactor concepts are being developed to use more advanced materials, coolants and higher burn-ups fuels, while keeping a nuclear reactor safe and reliable. One of the six Generation-IV concepts is a very high temperature reactor (VHTR). The VHTR concept uses a graphite-moderated core with a once-through uranium fuel cycle, using high temperature helium as the coolant. Because helium is naturally inert and single-phase, the helium-cooled reactor can operate at much higher temperatures, leading to higher efficiency. Current VHTR concepts will use fuels such as uranium dioxide, uranium carbide, or uranium oxycarbide. Since some of these fuels are new in nuclear industry and due to their unknown properties and behavior within VHTR conditions it is very important to address these issues by investigate their characteristics within conditions close to those in VHTRs. This research can be performed in a research reactor with in-pile helium loop designed and constructed in Research Center Rez Ltd. One of the topics analyzed in this article are also physical characteristic and benefits of gas

  9. Fuel Maps for the GEP 6.5LT Engine When Operating on at J/JP-8 Fuel Blends at Ambient and Elevated Temperatures

    Science.gov (United States)

    2015-04-01

    UNCLASSIFIED UNCLASSIFIED FUEL MAPS FOR THE GEP 6.5LT ENGINE WHEN OPERATING ON ATJ/JP-8 FUEL BLENDS AT AMBIENT AND ELEVATED TEMPERATURES...INTERIM REPORT TFLRF No. 464 By Douglas M. Yost Edwin A. Frame U.S. Army TARDEC Fuels and Lubricants Research Facility Southwest... FUEL MAPS FOR THE GEP 6.5LT ENGINE WHEN OPERATING ON ATJ/JP-8 FUEL BLENDS AT AMBIENT AND ELEVATED TEMPERATURES INTERIM REPORT TFLRF No. 464

  10. Exceptional durability enhancement of PA/PBI based polymer electrolyte membrane fuel cells for high temperature operation at 200°C

    DEFF Research Database (Denmark)

    Aili, David; Zhang, Jin; Jakobsen, Mark Tonny Dalsgaard

    2016-01-01

    The incorporation of phosphotungstic acid functionalized mesoporous silica in phosphoric acid doped polybenzimidazole (PA/PBI) substantially enhances the durability of PA/PBI based polymer electrolyte membrane fuel cells for high temperature operation at 200°C.......The incorporation of phosphotungstic acid functionalized mesoporous silica in phosphoric acid doped polybenzimidazole (PA/PBI) substantially enhances the durability of PA/PBI based polymer electrolyte membrane fuel cells for high temperature operation at 200°C....

  11. Sequence development of a latest Devonian-Tournaisian distally-steepened mixed carbonate-siliciclastic ramp, Canning Basin, Australia

    Science.gov (United States)

    Seyedmehdi, Zahra; George, Annette D.; Tucker, Maurice E.

    2016-03-01

    The sequence development and evolution of latest Devonian-earliest Carboniferous Fairfield Group in the Canning Basin have been established through integration of detailed sedimentological analysis of core, petrophysical data, existing biostratigraphic data and new seismic interpretations. The Fairfield Group on the Lennard Shelf was deposited on a mixed carbonate-siliciclastic distally-steepened ramp with a broad inner ramp, narrow mid ramp and steepened outer ramp. The majority of facies associations (FA1-FA8) were formed in intertidal-shallow subtidal conditions in proximal to distal inner ramp including siliciclastic tidal flats (FA1), carbonate intertidal flats (FA2), tidal flats and channels (FA3), lagoons (FA4-FA5), and shallow subtidal (FA6), backshoal (FA7) and fore-shoal areas (FA8). Bioclastic muddy sandstone (FA9) and bioclastic mudstone (FA10) are the dominant mid-ramp facies. Recognition of turbiditic facies of middle to lower slope of the outer ramp (FA11-FA13) led to the identification of a distally-steepened ramp. Antecedent topography exerted a significant control on platform morphology and the development of the widespread inner-ramp facies on the Lennard Shelf. A sequence-stratigraphic analysis reveals that the Fairfield Group ramp deposits consists of four third-order sequences (S1-S4) that were largely deposited during sea-level highstands (HST) characterized by progradational trends and dominant shallow subtidal inner-ramp facies associations. Transgressive systems tracts (TST) are well developed in S1 and S3 and have a retrogradational facies pattern with dominant deep subtidal mid-outer ramp facies associations. Lowstand systems tracts, characterized by lowstand wedges and turbiditic facies, are identified in the lower parts of S2 and S3. Coarse and fine-grained siliciclastic facies are mixed with carbonate facies as a result of coeval deposition on the inner and mid ramp, and reciprocal deposition on the outer ramp. A temporal variation in

  12. XS-1 on ramp with B-29 mothership

    Science.gov (United States)

    1949-01-01

    XS-1 on the ramp with the B-29 mothership in 1949. This is the second XS-1 built; it later was converted into the X-1E. Unlike the XS-1-1, which was flown by the Air Force, the XS-1-2 was flown mostly by Bell and NACA pilots. It gathered much more research data than the more famous XS-1-1, known as 'Glamorous Glennis.' The first of the rocket-powered research aircraft, the X-1 (originally designated the XS-1), was a bullet-shaped airplane that was built by the Bell Aircraft Company for the US Air Force and the NACA. The mission of the X-1 was to investigate the transonic speed range (speeds from just below to just above the speed of sound) and, if possible, to break the 'sound barrier.' The first of the three X-1s was glide-tested at Pinecastle Army Air Field, FL, in early 1946. The first powered flight of the X-1 was made on Dec. 9, 1946, at Edwards Air Force Base with Chalmers Goodlin, a Bell test pilot, at the controls. On Oct. 14, 1947, with USAF Captain Charles 'Chuck' Yeager as pilot, the aircraft flew faster than the speed of sound for the first time. Captain Yeager ignited the four-chambered XLR-11 rocket engines after the B-29 air-launched it from under the bomb bay of a B-29 at 21,000 feet. The 6,000-pound thrust ethyl alcohol/liquid oxygen burning rockets, built by Reaction Motors, Inc., pushed the aircraft up to a speed of 700 miles per hour in level flight. Captain Yeager was also the pilot when the X-1 reached its maximum speed, 957 miles per hour. Another USAF pilot. Lt. Col. Frank Everest, Jr., was credited with taking the X-1 to its maximum altitude of 71,902 feet. Eighteen pilots in all flew the X-1s. The number three plane was destroyed in a fire before ever making any powered flights. A single-place monoplane, the X-1 was 30 feet, 11 inches long; 10 feet, 10 inches high; and had a wingspan of 29 feet. It weighed 6,784 pounds and carried 6,250 pounds of fuel. It had a flush cockpit with a side entrance and no ejection seat.

  13. Theoretical Study of Midwave Infrared HgCdTe nBn Detectors Operating at Elevated Temperatures

    Science.gov (United States)

    Akhavan, Nima Dehdashti; Jolley, Gregory; Umana-Membreno, Gilberto A.; Antoszewski, Jarek; Faraone, Lorenzo

    2015-09-01

    We report a theoretical study of mercury cadmium telluride (HgCdTe) unipolar n-type/barrier/ n-type (nBn) detectors for midwave infrared (MWIR) applications at elevated temperatures. The results obtained indicate that the composition, doping, and thickness of the barrier layer in MWIR HgCdTe nBn detectors can be optimized to yield performance levels comparable with those of ideal HgCdTe p- n photodiodes. It is also shown that introduction of an additional barrier at the back contact layer of the detector structure (nBnn+) leads to substantial suppression of the Auger generation-recombination (GR) mechanism; this results in an order-of-magnitude reduction in the dark current level compared with conventional nBn or p- n junction-based detectors, thus enabling background-limited detector operation above 200 K.

  14. Fuel cells using ionic liquids as electrolyte and operating at room temperature; Celulas de combustivel utilizando como eletrolito liquidos ionicos e operando a temperatura ambiente

    Energy Technology Data Exchange (ETDEWEB)

    Botton, Janine Padilha; Souza, Roberto Fernando de; Goncalves, Reinaldo Simoes; Dupont, Jairton [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Inst. de Quimica], e-mail: janine@iq.ufrgs.br

    2004-07-01

    The room temperature imidazolium based ionic liquids, such as 1-n-butyl-3-methylimidazolium tetrafluoroborate (BMI.BF4) are outstanding electrolytes for fuel cells. A 67% overall cell efficiency is achieve using these liquids as supporting electrolytes for a commercially available alkaline fuel cell (AFC) at room temperature operating with air and hydrogen at atmospheric pressure. (author)

  15. An operational method for the disaggregation of land surface temperature to estimate actual evapotranspiration in the arid region of Chile

    Science.gov (United States)

    Olivera-Guerra, L.; Mattar, C.; Merlin, O.; Durán-Alarcón, C.; Santamaría-Artigas, A.; Fuster, R.

    2017-06-01

    Monitoring evapotranspiration in arid and semi-arid environments plays a key role in water irrigation scheduling for water use efficiency. This work presents an operational method for evapotranspiration retrievals based on disaggregated Land Surface Temperature (LST). The retrieved LSTs from Landsat-8 and MODIS data were merged in order to provide an 8-day composite LST product at 100 × 100 m resolution. The method was tested in the arid region of Copiapó, Chile using data from years 2013-2014 and validated using data from years 2015-2016. In-situ measurements from agrometeorological stations such as air temperature and potential evapotranspiration (ET0) estimated at the location were used in the ET estimation method. The disaggregation method was developed by taking into account (1) the spatial relationship between Landsat-8 and MODIS LST, (2) the spatial relationship between LST and the Normalized Difference Vegetation Index (NDVI) at high spatial resolution (Landsat-8), and (3) the temporal variations along the year of both relationships aforementioned. The comparison between disaggregated LST at 100 m resolution and in situ LST measurements presents a coefficient of determination (r2), in average, equal to 0.70 and a RMSE equal to 3.6 K. The disaggregated LST was used in an operational model to estimate the actual evapotranspiration (ETa). The ETa shows good results in terms of seasonal variations and in comparison to the evapotranspiration estimated by using crop coefficients (kc). The comparison between remotely sensed and in situ ETa presents an overall r2 close to 0.67 and a RMSE equal to 0.6 mm day-1 for both crops. These results are important for further improvements in water use sustainability in the Copiapó valley, which is currently affected by high water demand.

  16. Numerical Simulation on Ramp Initiation and Propagation in a Fold-and-thrust Belt and Accretionary Wedge

    Science.gov (United States)

    Hu, C.; Liu, X.; Shi, Y.

    2015-12-01

    Fold-and-thrust belts and accretionary wedge develop along compressive plate boundaries, both in hinterland and foreland. Under the long-term compressive tectonic loading, a series ramps will initiate and propagate along the wedge. How do the ramps initiate? What are the timing and spacing intervals between the ramps? How many patterns are there for the ramp propagation? These questions are basic for the study of ramp initiation and propagation. Many scholars used three different methods, critical coulomb wedge theory, analogue sandbox models, and numerical simulation to research the initiation and propagation of the ramps, respectively. In this paper, we set up a 2-D elastic-plastic finite element model, with a frictional contact plane, to simulate the initiation and propagation of the ramps. In this model, the material in upper wedge is homogenous, but considering the effects of gravity and long-term tectonic loading. The model is very simple but simulated results are very interesting. The simulated results indicate that the cohesion of upper wedge and dip angle of detachment plane have strong effects on the initiation and propagation of ramps. There are three different patterns of ramp initiation and propagation for different values of the cohesion. The results are different from those by previous analogue sandbox models, and numerical simulation, in which there is usually only one pattern for the ramp initiation and propagation. The results are consistent with geological survey for the ramp formation in an accretionary wedge. This study will provide more knowledge of mechanism of the ramp initiation and propagation in Tibetan Plateau and central Taiwan.

  17. A new sensor for ammonia based on cyanidin-sensitized titanium dioxide film operating at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Xiao-wei, Huang [School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, 212013 Zhenjiang, Jiangsu (China); Xiao-bo, Zou, E-mail: zou_xiaobo@ujs.edu.cn [School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, 212013 Zhenjiang, Jiangsu (China); Key Laboratory of Modern Agricultural Equipment and Technology, 301 Xuefu Road, 212013 Zhenjiang, Jiangsu (China); Ji-yong, Shi; Jie-wen, Zhao; Yanxiao, Li [School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, 212013 Zhenjiang, Jiangsu (China); Limin, Hao; Jianchun, Zhang [The Research Center of China Hemp Materials, Beijing (China)

    2013-07-17

    Graphical abstract: -- Highlights: •TiO{sub 2} was prepared by sol–gel method film and then functionalized with the cyanidin dye. •The morphology and the absorption spectra of films were examined. •The hybrid organic–inorganic formed film here can detect ammonia reversibly at room temperature. •The low humidity could promote the sensitivity of the sensors. -- Abstract: Design and fabrication of an ammonia sensor operating at room temperature based on pigment-sensitized TiO{sub 2} films was described. TiO{sub 2} was prepared by sol–gel method and deposited on glass slides containing gold electrodes. Then, the film immersed in a 2.5 × 10{sup −4} M ethanol solution of cyanidin to absorb the pigment. The hybrid organic–inorganic formed film here can detect ammonia reversibly at room temperature. The relative change resistance of the films at a potential difference of 1.5 V is determined when the films are exposed to atmospheres containing ammonia vapors with concentrations over the range 10–50 ppm. The relative change resistance, S, of the films increased almost linearly with increasing concentrations of ammonia (r = 0.92). The response time to increasing concentrations of the ammonia is about 180–220 s, and the corresponding values for decreasing concentrations 240–270 s. At low humidity, ammonia could be ionized by the cyanidin on the TiO{sub 2} film and thereby decrease in the proton concentration at the surface. Consequently, more positively charged holes at the surface of the TiO{sub 2} have to be extracted to neutralize the adsorbed cyanidin and water film. The resistance response to ammonia of the sensors was nearly independent on temperature from 10 to 50 °C. These results are not actually as good as those reported in the literature, but this preliminary work proposes simpler and cheaper processes to realize NH{sub 3} sensor for room temperature applications.

  18. The Composite Operator (CJT) Formalism in the $(\\lambda\\phi^4+\\eta\\phi^{6})_{D=3}$ Model at Finite Temperature

    CERN Document Server

    Añaños, G N J

    2000-01-01

    We discuss three-dimensional $ \\lambda\\phi^4+\\eta\\phi^6 $ theory in the context of the 1/N expansion at finite temperature. We use the method of the composite operator (CJT) for summing a large sets of Feynman graphs. We analyse the behavior of the thermal square mass and the thermal coupling constant in the low and high temperature limit. The existent of the tricritical point at some temperature is found using this non-pertubative method.

  19. Failure Mechanisms and Color Stability in Light-Emitting Diodes during Operation in High- Temperature Environments in Presence of Contamination

    Energy Technology Data Exchange (ETDEWEB)

    Lall, Pradeep; Zhang, Hao; Davis, J Lynn

    2015-05-26

    The energy efficiency of light-emitting diode (LED) technology compared to incandescent light bulbs has triggered an increased focus on solid state luminaries for a variety of lighting applications. Solid-state lighting (SSL) utilizes LEDs, for illumination through the process of electroluminescence instead of heating a wire filament as seen with traditional lighting. The fundamental differences in the construction of LED and the incandescent lamp results in different failure modes including lumen degradation, chromaticity shift and drift in the correlated color temperature. The use of LED-based products for safety-critical and harsh environment applications necessitates the characterization of the failure mechanisms and modes. In this paper, failure mechanisms and color stability has been studied for commercially available vertical structured thin film LED (VLED) under harsh environment conditions with and without the presence of contaminants. The VLED used for the study was mounted on a ceramic starboard in order to connect it to the current source. Contamination sources studied include operation in the vicinity of vulcanized rubber and adhesive epoxies in the presence of temperature and humidity. Performance of the VLEDs has been quantified using the measured luminous flux and color shift of the VLEDs subjected to both thermal and humidity stresses under a forward current bias of 350 mA. Results indicate that contamination can result in pre-mature luminous flux degradation and color shift in LEDs.

  20. Material characterisation and preliminary mechanical design for the HL-LHC shielded beam screens operating at cryogenic temperatures

    CERN Document Server

    Garion, C; Koettig, T; Machiocha, W; Morrone, M

    2015-01-01

    The High Luminosity LHC project (HL-LHC) aims at increasing the luminosity (rate of collisions) in the Large Hadron Collider (LHC) experiments by a factor of 10 beyond the original design value (from 300 to 3000 fb-1). It relies on new superconducting magnets, installed close to the interaction points, equipped with new beam screen. This component has to ensure the vacuum performance together with shielding the cold mass from physics debris and screening the cold bore cryogenic system from beam induced heating. The beam screen operates in the range 40-60 K whereas the magnet cold bore temperature is 1.9 K. A tungsten-based material is used to absorb the energy of particles. In this paper, measurements of the mechanical and physical properties of such tungsten material are shown at room and cryogenic temperature. In addition, the design and the thermal mechanical behaviour of the beam screen assembly are presented also. They include the heat transfer from the tungsten absorbers to the cooling pipes and the sup...