WorldWideScience

Sample records for cell temperature coefficients

  1. Modelling of tandem cell temperature coefficients

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, D.J. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    This paper discusses the temperature dependence of the basic solar-cell operating parameters for a GaInP/GaAs series-connected two-terminal tandem cell. The effects of series resistance and of different incident solar spectra are also discussed.

  2. Temperature coefficients for GaInP/GaAs/GaInNAsSb solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Aho, Arto; Isoaho, Riku; Tukiainen, Antti; Polojärvi, Ville; Aho, Timo; Raappana, Marianna; Guina, Mircea [Optoelectronics Research Centre, Tampere University of Technology, P.O. Box 692, FIN-33101 Tampere (Finland)

    2015-09-28

    We report the temperature coefficients for MBE-grown GaInP/GaAs/GaInNAsSb multijunction solar cells and the corresponding single junction sub-cells. Temperature-dependent current-voltage measurements were carried out using a solar simulator equipped with a 1000 W Xenon lamp and a three-band AM1.5D simulator. The triple-junction cell exhibited an efficiency of 31% at AM1.5G illumination and an efficiency of 37–39% at 70x real sun concentration. The external quantum efficiency was also measured at different temperatures. The temperature coefficients up to 80°C, for the open circuit voltage, the short circuit current density, and the conversion efficiency were determined to be −7.5 mV/°C, 0.040 mA/cm{sup 2}/°C, and −0.09%/°C, respectively.

  3. Temperature coefficients for GaInP/GaAs/GaInNAsSb solar cells

    Science.gov (United States)

    Aho, Arto; Isoaho, Riku; Tukiainen, Antti; Polojärvi, Ville; Aho, Timo; Raappana, Marianna; Guina, Mircea

    2015-09-01

    We report the temperature coefficients for MBE-grown GaInP/GaAs/GaInNAsSb multijunction solar cells and the corresponding single junction sub-cells. Temperature-dependent current-voltage measurements were carried out using a solar simulator equipped with a 1000 W Xenon lamp and a three-band AM1.5D simulator. The triple-junction cell exhibited an efficiency of 31% at AM1.5G illumination and an efficiency of 37-39% at 70x real sun concentration. The external quantum efficiency was also measured at different temperatures. The temperature coefficients up to 80°C, for the open circuit voltage, the short circuit current density, and the conversion efficiency were determined to be -7.5 mV/°C, 0.040 mA/cm2/°C, and -0.09%/°C, respectively.

  4. Temperature coefficients for GaInP/GaAs/GaInNAsSb solar cells

    International Nuclear Information System (INIS)

    We report the temperature coefficients for MBE-grown GaInP/GaAs/GaInNAsSb multijunction solar cells and the corresponding single junction sub-cells. Temperature-dependent current-voltage measurements were carried out using a solar simulator equipped with a 1000 W Xenon lamp and a three-band AM1.5D simulator. The triple-junction cell exhibited an efficiency of 31% at AM1.5G illumination and an efficiency of 37–39% at 70x real sun concentration. The external quantum efficiency was also measured at different temperatures. The temperature coefficients up to 80°C, for the open circuit voltage, the short circuit current density, and the conversion efficiency were determined to be −7.5 mV/°C, 0.040 mA/cm2/°C, and −0.09%/°C, respectively

  5. On the definition of the fuel temperature coefficient of reactivity for pin-cell calculations on an infinite lattice

    International Nuclear Information System (INIS)

    The fuel temperature coefficient of reactivity is an important parameter in the evaluation of transients in light water reactors. The fuel temperature coefficient of an infinite lattice, often used in pin-cell calculations, is not a correct measure for the fuel temperature effect in such a lattice. We present a somewhat different definition of the fuel temperature coefficient of reactivity. This definition gives a more correct measure for the fuel temperature effect. Some calculations on lattices which are characteristic for a PWR show its accuracy. The newly defined fuel temperature coefficient is much less dependent on the fuel enrichment and the 10B-concentration. The fuel temperature coefficient is analysed by calculating the different components constituting this coefficient. (orig.)

  6. VHTRC temperature coefficient benchmark problem

    International Nuclear Information System (INIS)

    As an activity of IAEA Coordinated Research Programme, a benchmark problem is proposed for verifications of neutronic calculation codes for a low enriched uranium fuel high temperature gas-cooled reactor. Two problems are given on the base of heating experiments at the VHTRC which is a pin-in-block type core critical assembly loaded mainly with 4% enriched uranium coated particle fuel. One problem, VH1-HP, asks to calculate temperature coefficient of reactivity from the subcritical reactivity values at five temperature steps between an room temperature where the assembly is nearly at critical state and 200degC. The other problem, VH1-HC, asks to calculate the effective multiplication factor of nearly critical loading cores at the room temperature and 200degC. Both problems further ask to calculate cell parameters such as migration area and spectral indices. Experimental results corresponding to main calculation items are also listed for comparison. (author)

  7. Quantum efficiency and temperature coefficients of GaInP/GaAs dual-junction solar cell

    Institute of Scientific and Technical Information of China (English)

    LIU Lei; CHEN NuoFu; BAI YiMing; CUI Ming; ZHANG Han; GAO FuBao; YIN ZhiGang; ZHANG XingWang

    2009-01-01

    GalnP/GaAs dual-junction solar cell with a conversion efficiency of 25.2% has been fabricated using metalorganic chemical vapor deposition (MOCVD) technique. Quantum efficiencies of the solar cell were measured within a temperature range from 25 to 160℃. The results indicate that the quantum ef-ficiencies of the subcells increase slightly with the increasing temperature. And red-shift phenomena of absorption limit for all subcells are observed by increasing the cell's work temperature, which are consistent with the viewpoint of energy gap narrowing effect. The short-circuit current density tem-perature coefficients dJoc/dT of GalnP subcell and GaAs subcell are determined to be 8.9 and 7.4 μA/cm2/℃ from the quantum efficiency data, respectively. And the open-circuit cell voltage temperature coefficients d Voc/d T calculated based on a theoretical equation are -2.4 mV/℃ and -2.1 mV/℃ for GalnP subcell and GaAs subcell.

  8. Quantum efficiency and temperature coefficients of GaInP/GaAs dual-junction solar cell

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    GaInP/GaAs dual-junction solar cell with a conversion efficiency of 25.2% has been fabricated using metalorganic chemical vapor deposition(MOCVD) technique.Quantum efficiencies of the solar cell were measured within a temperature range from 25 to 160 ℃.The results indicate that the quantum ef-ficiencies of the subcells increase slightly with the increasing temperature.And red-shift phenomena of absorption limit for all subcells are observed by increasing the cell’s work temperature,which are consistent with the viewpoint of energy gap narrowing effect.The short-circuit current density tem-perature coefficients dJsc/dT of GaInP subcell and GaAs subcell are determined to be 8.9 and 7.4 μA/cm2/℃ from the quantum efficiency data,respectively.And the open-circuit cell voltage temperature coefficients dVoc/dT calculated based on a theoretical equation are-2.4 mV/℃ and-2.1 mV/℃ for GaInP subcell and GaAs subcell.

  9. Measuring optical temperature coefficients of Intralipid (registered)

    International Nuclear Information System (INIS)

    The temperature sensitivities of absorption and reduced scattering coefficients in the range 700-1000 nm are determined for the liquid phantom Intralipid (registered) using spatially resolved continuous wave measurements. The measurements were conducted on a 10 L heated volume of 1% Intralipid (registered) subjected to a 40-30 deg. C cooling regime. The temperature sensitivities of the absorbance coefficients are similar to that expected for pure water. However, the reduced scattering coefficients are more sensitive than can be explained by temperature related density changes, and show an unexpected relationship with wavelength. We have also found that temperature perturbations provide a useful means to evaluate instrument model performance

  10. Temperature dependence of the optical absorption coefficient of microcrystalline silicon

    OpenAIRE

    Poruba, A.; Špringer, J.; Mullerova, L.; Beitlerova, A.; Vaněček, M.; Wyrsch, Nicolas; Shah, Arvind

    2008-01-01

    The optical absorption coefficient of amorphous and microcrystalline silicon was determined in a spectral range 400–3100 nm and a temperature range 77–350 K. Transmittance measurement and Fourier transform photocurrent spectroscopy were used. The measured data served as an input for our optical model of amorphous/microcrystalline tandem solar cell. Differences in the current generated in the amorphous and microcrystalline parts were computed, for an operating temperature between −20 °C and +8...

  11. Compilation report of VHTRC temperature coefficient benchmark calculations

    Energy Technology Data Exchange (ETDEWEB)

    Yasuda, Hideshi; Yamane, Tsuyoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1995-11-01

    A calculational benchmark problem has been proposed by JAERI to an IAEA Coordinated Research Program, `Verification of Safety Related Neutronic Calculation for Low-enriched Gas-cooled Reactors` to investigate the accuracy of calculation results obtained by using codes of the participating countries. This benchmark is made on the basis of assembly heating experiments at a pin-in block type critical assembly, VHTRC. Requested calculation items are the cell parameters, effective multiplication factor, temperature coefficient of reactivity, reaction rates, fission rate distribution, etc. Seven institutions from five countries have joined the benchmark works. Calculation results are summarized in this report with some remarks by the authors. Each institute analyzed the problem by applying the calculation code system which was prepared for the HTGR development of individual country. The values of the most important parameter, k{sub eff}, by all institutes showed good agreement with each other and with the experimental ones within 1%. The temperature coefficient agreed within 13%. The values of several cell parameters calculated by several institutes did not agree with the other`s ones. It will be necessary to check the calculation conditions again for getting better agreement. (J.P.N.).

  12. Temperature conversion of coefficient of thermal conductivity

    Czech Academy of Sciences Publication Activity Database

    Mareš, R.; Šifner, Oldřich

    2002/, č. 1 (2002), s. 65-70. ISSN 1211-9652. [IAPWS Meeting 2002. Argentina , 21.08.2002-26.08.2002] Institutional research plan: CEZ:AV0Z2076919 Keywords : temperature conversion * thermal conductivity Subject RIV: BJ - Thermodynamics

  13. Isothermal temperature reactivity coefficient measurement in TRIGA reactor

    International Nuclear Information System (INIS)

    Direct measurement of an isothermal temperature reactivity coefficient at room temperatures in TRIGA Mark II research reactor at Jozef Stefan Institute in Ljubljana is presented. Temperature reactivity coefficient was measured in the temperature range between 15 oC and 25 oC. All reactivity measurements were performed at almost zero reactor power to reduce or completely eliminate nuclear heating. Slow and steady temperature decrease was controlled using the reactor tank cooling system. In this way the temperatures of fuel, of moderator and of coolant were kept in equilibrium throughout the measurements. It was found out that TRIGA reactor core loaded with standard fuel elements with stainless steel cladding has small positive isothermal temperature reactivity coefficient in this temperature range.(author)

  14. Temperature and Coefficient of Restitution of a Table Tennis Ball

    Directory of Open Access Journals (Sweden)

    Yoonyoung Chang

    2016-01-01

    Full Text Available The coefficient of restitution (COR of a bouncing table tennis ball was measured at varying ball temperatures with a Motion Detector. It was found that there is a negative linear relationship between the COR and the temperature of the table tennis ball for temperatures ranging from 5 to 56 ̊C.

  15. Prompt temperature feedback coefficient measurement of TRR-1/M 1

    International Nuclear Information System (INIS)

    Prompt temperature feedback coefficient measurement of TRR-1M/1 (TRIGA MARK III) at the Office of Atomic Energy for Peace was carried out by direct measurements of heat transfer and reactor power characteristics during small power excursion experiment (reactivities less than 60 cent). An instrumented fuel element at position Bl was used to measure the temperature characteristic of fuel elements. From measured reactivities and heat transfer, prompt temperature feedback coefficient was calculated by using prompt-jump and one-delayed-neutron-group approximated diffusion equation, Newton's Law of Cooling, and linear reactivity equation. The core loading was mainly standard fuel elements. Averaged value of prompt temperature feedback coefficient obtained was-1.39 cent/degree C over the temperature range from 53 degree C to 57 degree C. The result is comparable to that obtained, by similar experiment, at the University of Arizona and about 16 percent above that reported by General Atomic Company, supplier of the reactor

  16. Temperature dependence of the Soret coefficient of ionic colloids

    Science.gov (United States)

    Sehnem, A. L.; Figueiredo Neto, A. M.; Aquino, R.; Campos, A. F. C.; Tourinho, F. A.; Depeyrot, J.

    2015-10-01

    The temperature dependence of the Soret coefficient ST(T ) in electrostatically charged magnetic colloids is investigated. Two different ferrofluids, with different particles' mean dimensions, are studied. In both cases we obtain a thermophilic behavior of the Soret effect. The temperature dependence of the Soret coefficient is described assuming that the nanoparticles migrate along the ionic thermoelectric field created by the thermal gradient. A model based on the contributions from the thermoelectrophoresis and variation of the double-layer energy, without fitting parameters, is used to describe the experimental results of the colloid with the bigger particles. To do so, independent measurements of the ζ potential, mass diffusion coefficient, and Seebeck coefficient are performed. The agreement of the theory and the experimental results is rather good. In the case of the ferrofluid with smaller particles, it is not possible to get experimentally reliable values of the ζ potential and the model described is used to evaluate this parameter and its temperature dependence.

  17. A high temperature apparatus for measurement of the Seebeck coefficient

    OpenAIRE

    Iwanaga, Shiho; Toberer, Eric S.; LaLonde, Aaron; Snyder, G. Jeffrey

    2011-01-01

    A high temperature Seebeck coefficient measurement apparatus with various features to minimize typical sources of error is designed and built. Common sources of temperature and voltage measurement error are described and principles to overcome these are proposed. With these guiding principles, a high temperature Seebeck measurement apparatus with a uniaxial 4-point contact geometry is designed to operate from room temperature to over 1200 K. This instrument design is simple to operate, and su...

  18. The HD+ dissociative recombination rate coefficient at low temperature

    Directory of Open Access Journals (Sweden)

    Wolf A.

    2015-01-01

    Full Text Available The effect of the rotational temperature of the ions is considered for low-energy dissociative recombination (DR of HD+. Merged beams measurements with HD+ ions of a rotational temperature near 300 K are compared to multichannel quantum defect theory calculations. The thermal DR rate coefficient for a Maxwellian electron velocity distribution is derived from the merged-beams data and compared to theoretical results for a range of rotational temperatures. Good agreement is found for the theory with 300 K rotational temperature. For a low-temperature plasma environment where also the rotational temperature assumes 10 K, theory predicts a considerably higher thermal DR rate coefficient. The origin of this is traced to predicted resonant structures of the collision-energy dependent DR cross section at few-meV collision energies for the particular case of HD+ ions in the rotational ground state.

  19. Changes of the temperature coefficients of the characteristics which accompany degradation and recovery of a-Si solar cells; A-Si taiyo denchi no hikari (denryu) rekka oyobi kaifuku ni tomonau tokusei ondo keisu no henka

    Energy Technology Data Exchange (ETDEWEB)

    Yanagisawa, T.; Koyanagi, T.; Nakamura, K.; Takahisa, K.; Kojima, T. [electrotechnical Laboratory, Tsukuba (Japan)

    1996-10-27

    Pursuant to the measuring of temperature dependency of the characteristics such as conversion efficiency, during the process of degradation in a-Si solar cells due to light and electric current and the process of recovery by annealing, this paper describes changes in temperature coefficients, correlation between the characteristic parameters and the degradation, and the results of the examination of their characteristics. The conversion efficiency {mu} degraded approximately by 45% of the initial value each by the irradiation under a light intensity with 3 SUN accelerated and by the infusion of current at 20mA/cm{sup 2}; and then, the efficiency recovered to 70-75% of the degradation by subsequent annealing. In addition, in the temperature dependency at 80{degree}C against at 20{degree}C, Isc slightly increased while Vcc greatly decreased. This slight increase in Isc was mainly due to the decrease in the width of the forbidden band, while the decrease in Vcc was due to the increase in the reverse saturation current. The temperature dependency of {mu}N was negative, becoming small in accordance with the degradation. The temperature dependency of FF/FFO was negative initially both in light and current, but it decreased with the degradation and turned to positive. The temperature coefficients of I-V parameters reversibly changed corresponding to the degradation and recovery of these parameters and stayed in a good correlation. 7 refs., 8 figs., 1 tab.

  20. Measurement of thermal expansion coefficient of nonuniform temperature specimen

    Institute of Scientific and Technical Information of China (English)

    Jingmin Dai; Chunsuo Kin; Xiaowa He

    2008-01-01

    A new technique is developed to measure the longitudinal thermal expansion coefficient of C/C composite material at high temperature. The measuring principle and components of the apparatus are described in detail. The calculation method is derived from the temperature dependence of the thermal expansion coefficient. The apparatus mainly consists of a high temperature environmental chamber, a power circuit of heating, two high-speed pyrometers, and a laser scanning system. A long solid specimen is resistively heated to a steady high-temperature state by a steady electrical current. The temperature profile of the specimen surface is not uniform because of the thermal conduction and radiation. The temperature profile and the total expansion are measured with a high-speed scanning pyrometer and a laser slit scanning measuring system, respectively. The thermal expansion coefficient in a wide temperature range (1000 - 3800 K) of the specimen can therefore be obtained. The perfect consistency between the present and previous results justifies the validity of this technique.

  1. Fully automated setup for high temperature Seebeck coefficient measurement

    CERN Document Server

    Patel, Ashutosh

    2016-01-01

    In this work, we report the fabrication of fully automated experimental setup for high temperature Seebeck coefficient ($\\alpha$) measurement. The K-type thermocouples are used to measure the average temperature of the sample and Seebeck voltage (SV) across it. The temperature dependence of the Seebeck coefficients of the thermocouple and its negative leg is taken care by using the integration method. Steady state based differential technique is used for $\\alpha$ measurement. Use of limited component and thin heater simplify the sample holder design and minimize the heat loss. The power supplied to the heater decides temperature difference across the sample and measurement is carried out by achieving the steady state. The LabVIEW based program is built to automize the whole measurement process. The complete setup is fabricated by using commonly available materials in the market. This instrument is standardized for materials with a wide range of $\\alpha$ and for the wide range of $\\Delta T$ across the specimen...

  2. Temperature dependence of Soret and diffusion coefficients for toluene-cyclohexane mixture measured in convection-free environment.

    Science.gov (United States)

    Mialdun, A; Shevtsova, V

    2015-12-14

    We report on the measurement of diffusion (D), Soret (S(T)), and thermodiffusion (D(T)) coefficients in toluene-cyclohexane mixture with mass fraction of toluene 0.40 onboard of the International Space Station. The coefficients were measured in the range of the mean temperatures between 20 °C and 34 °C. The Soret coefficient is negative within the investigated temperature range and its absolute value |S(T)| decreases with increasing temperature. The diffusion coefficient for this system increases with temperature rising. For comparison, the temperature dependence of diffusion coefficient was measured in ground laboratory using counter-flow cell technique and revealed a good agreement with microgravity results. A non-direct comparison of the measured onboard Soret coefficients with different systems indicated a similar trend for the temperature dependent behavior. Unexpected experimental finding is that for this system the thermodiffusion coefficient D(T) does not depend on temperature. PMID:26671399

  3. High Pressure Seebeck Coefficient Measurements Using Paris-Edinburgh Cell

    Science.gov (United States)

    Baker, Jason; Kumar, Ravhi; Park, Changyong; Kenney-Benson, Curtis; Velisavljevic, Nenad; Hipsec; Department Of Physics, University Of Nevada, Las Vegas Collaboration; Hpcat, Geophysical Laboratory, Carnegie Institution Of Washington Collaboration; Shock; Detonation Physics Group, Los Alamos National Laboratory Collaboration

    We have developed a new type of sample cell assembly for the Paris-Edinburgh (PE) type large volume press for simultaneous x-ray diffraction, electrical resistance, and thermal measurements at high pressures. We demonstrate the feasibility of performing in situ measurements of the Seebeck coefficient over a broad range of pressure-temperature conditions by observing the well-known solid-solid and solid-melt transitions of bismuth (Bi) up to 3GPa and 450 K. We observed a gradual increase in the Seebeck coefficient which becomes positive during transition to the Bi - II phase. Also, we have performed successful Seebeck coefficient measurements on the thermoelectric material PbTe. This new capability enables us to directly correlate pressure-induced structural phase transitions to electrical and thermal properties.

  4. Temperature dependence of the Soret coefficient of ionic colloids.

    Science.gov (United States)

    Sehnem, A L; Figueiredo Neto, A M; Aquino, R; Campos, A F C; Tourinho, F A; Depeyrot, J

    2015-10-01

    The temperature dependence of the Soret coefficient S(T)(T) in electrostatically charged magnetic colloids is investigated. Two different ferrofluids, with different particles' mean dimensions, are studied. In both cases we obtain a thermophilic behavior of the Soret effect. The temperature dependence of the Soret coefficient is described assuming that the nanoparticles migrate along the ionic thermoelectric field created by the thermal gradient. A model based on the contributions from the thermoelectrophoresis and variation of the double-layer energy, without fitting parameters, is used to describe the experimental results of the colloid with the bigger particles. To do so, independent measurements of the ζ potential, mass diffusion coefficient, and Seebeck coefficient are performed. The agreement of the theory and the experimental results is rather good. In the case of the ferrofluid with smaller particles, it is not possible to get experimentally reliable values of the ζ potential and the model described is used to evaluate this parameter and its temperature dependence. PMID:26565244

  5. High temperature coefficient of resistance for a ferroelectric tunnel junction

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xiaolin; Tian, Bobo; Liu, Bolu; Wang, Xudong; Huang, Hai [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Yu Tian Road 500, Shanghai 200083 (China); University of Chinese Academy of Sciences, No. 19 A Yuquan Road, Beijing 100049 (China); Wang, Jianlu, E-mail: jlwang@mail.sitp.ac.cn, E-mail: xjmeng@mail.sitp.ac.cn; Zou, Yuhong; Sun, Shuo; Lin, Tie; Han, Li; Sun, Jinglan; Meng, Xiangjian, E-mail: jlwang@mail.sitp.ac.cn, E-mail: xjmeng@mail.sitp.ac.cn; Chu, Junhao [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Yu Tian Road 500, Shanghai 200083 (China)

    2015-08-10

    An infrared detector is proposed that is based on a ferroelectric tunnel junction (FTJ) working under bolometer-like principles. Electron tunneling, either direct or indirect, through the ferroelectric barrier depends on the temperature of the devices. During tunneling, infrared radiation alters the polarization of the ferroelectric film via pyroelectricity, resulting in a change in the barrier height of the tunnel junction. A high temperature coefficient of resistance of up to −3.86% was observed at room temperature. These results show that the FTJ structure has potential to be adapted for use in uncooled infrared detectors.

  6. Temperature Dependence of the Particle Diffusion Coefficient in Dust Grains

    Science.gov (United States)

    Pechal, Radim; Richterova, Ivana; Pavlu, Jiri; Safrankova, Jana; Nemecek, Zdenek

    2014-05-01

    During the interaction of ions/neutrals with dust grains, some of the particles are implanted into the grain and, as a consequence, the density gradient induces their diffusion toward the grain surface. Their release can cause a transport of these particles over large distances in space. In our laboratory experiment, measurements of the diffusion coefficient of the particles implanted into the dust grain are carried out in an electrodynamic quadrupole trap. Although experimental setup does not allow an assessment of the dust grain temperature, it can be modified (e.g., by changing thermal radiation from the surrounding walls, laser irradiation, etc.). We present an upgraded laboratory set-up and the resulting temperature dependence of diffusion coefficient estimations and discuss implications for the space dust.

  7. Unipolar memristive switching in bulk positive temperature coefficient ceramic thermistor

    Science.gov (United States)

    Wu, Hongya; Wang, Caihui; Fu, Hua; Zhou, Ji; Zheng, Shuzhi

    2016-01-01

    A memristive switching phenomena was investigated in macroscale bulk positive temperature coefficient (PTC) thermosensitive ceramics. (BaxSr1-x)TiO3, which is a well-known PTC thermistor, was taken as an example to analyze the memristive behavior of those macroscale bulk ceramics. Hysteretic current-voltage (I-V) characteristics, which are the features of memristor were obtained. The origin of the effect is attributed to the PTC thermosensitive characteristic of the bulk ceramics, and a switching mechanism driven by competing field-driven heat generation and heat dissipation was proposed.

  8. Study of the effect of 135Xe poison on the temperature coefficient of TRIGA fuel

    International Nuclear Information System (INIS)

    A study of the influence of 135Xe on the prompt negative temperature coefficient of the 14-MW Romanian TRIGA reactor has been performed. Because of its large absorption cross section below 0.1 eV, we expected that 135Xe might make a positive contribution to the temperature coefficient because the higher-energy neutrons are less likely to be absorbed by the Xe. This effect would be largest about 16 hours after reactor shutdown. In order to investigate this phenomenon, we have performed cell and core calculations for various fuel temperatures, burnups, and 135Xe levels. These calculations indeed show a positive contribution of 135Xe to the temperature coefficient, especially for high burnups, where little 167Er remains to absorb the higher-energy neutrons. Work is in progress to evaluate the effect of the smaller negative temperature coefficient on the consequences of reactivity insertion accidents in unfavorable situations of 135Xe poisoning of the Romanian TRIGA core. (author)

  9. N2-broadening coefficients of methyl chloride at room temperature

    International Nuclear Information System (INIS)

    Methyl chloride is of interest for atmospheric applications, since this molecule is directly involved in the catalytic destruction of ozone in the lower stratosphere. In a previous work [Bray et al. JQSRT 2011;112:2446], lines positions and intensities of self-perturbed 12CH335Cl and 12CH337Cl have been studied into details for the 3.4 μm spectral region. The present work is focused on measurement and calculation of N2-broadening coefficients of the 12CH335Cl and 12CH337Cl isotopologues. High-resolution Fourier Transform spectra of CH3Cl-N2 mixtures at room-temperature have been recorded between 2800 and 3200 cm-1 at LADIR (using a classical source) and between 47 and 59 cm-1 at SOLEIL (using the synchrotron source on the AILES beamline). 612 mid-infrared transitions of the ν1 band and 86 far-infrared transitions of the pure rotational band have been analyzed using a multispectrum fitting procedure. Average accuracy on the deduced N2-broadening coefficients has been estimated to 5% and 10% in the mid- and far-infrared spectral regions, respectively. The J- and K-rotational dependences of these coefficients have been observed in the mid-infrared region and then a simulation has been performed using an empirical model for 0≤J≤50, K≤9. The 12CH335Cl-N2 line widths for 0≤J≤50 and K≤10 of the ν1 band and for 55≤J≤67 and K≤15 of the pure rotational band have been computed using a semi-classical approach involving exact trajectories and a real symmetric-top geometry of the active molecule. Finally, a global comparison with the experimental and theoretical data existing in the literature has been performed. Similar J- and K-rotational dependences have been appeared while no clear evidence for any vibrational or isotopic dependences have been pointed out.

  10. Temperature dependence of Kerr coefficient and quadratic polarized optical coefficient of a paraelectric Mn:Fe:KTN crystal

    Directory of Open Access Journals (Sweden)

    Qieni Lu

    2015-08-01

    Full Text Available We measure temperature dependence on Kerr coefficient and quadratic polarized optical coefficient of a paraelectric Mn:Fe:KTN crystal simultaneously in this work, based on digital holographic interferometry (DHI. And the spatial distribution of the field-induced refractive index change can also be visualized and estimated by numerically retrieving sequential phase maps of Mn:Fe:KTN crystal from recording digital holograms in different states. The refractive indices decrease with increasing temperature and quadratic polarized optical coefficient is insensitive to temperature. The experimental results suggest that the DHI method presented here is highly applicable in both visualizing the temporal and spatial behavior of the internal electric field and accurately measuring electro-optic coefficient for electrooptical media.

  11. Monte Carlo analysis of doppler reactivity coefficient for UO2 pin cell geometry

    International Nuclear Information System (INIS)

    Monte Carlo analysis has been performed to investigate the impact of the exact resonance elastic scattering model on the Doppler reactivity coefficient for the UO2 pin cell geometry with the parabolic temperature profile. As a result, the exact scattering model affects the coefficient similarly for both the flat and parabolic temperature profiles; it increases the contribution of uranium-238 resonance capture in the energy region from ∼16 eV to ∼150 eV and does uniformly in the radial direction. Then the following conclusions hold for both the exact and asymptotic resonance scattering models. The Doppler reactivity coefficient is well reproduced with the definition of the effective fuel temperature (equivalent flat temperature) proposed by Grandi et al. In addition, the effective fuel temperature volume-averaged over the entire fuel region negatively overestimates the reference Doppler reactivity coefficient but the calculated one can be significantly improved by dividing the fuel region into a few equi-volumes. (author)

  12. Infrared spectroscopy at high temperature : N2- and O2-broadening coefficients in the ν4 band of CH4

    Science.gov (United States)

    Fissiaux, Laurent; Populaire, Jean-Claude; Blanquet, Ghislain; Lepère, Muriel

    2015-11-01

    In the present work, we have developed a high-temperature absorption cell for infrared spectroscopy. This absorption cell can contain gases of the room temperature up to 650 K without temperature gradient. The construction of the cell and its technical features are described in detail in this paper. In order to demonstrate the feasibility and the interest of the cell, we have measured the N2-, O2- and air-broadening coefficients of, respectively, six and three absorption lines in the ν4 band of methane at four temperatures (350, 425, 500, 575 K). The measurements of these coefficients was realized with a tunable diode-laser spectrometer. The line parameters were obtained by fitting to the experimental profile the Voigt line shape and the Rautian and Galatry models taking into account the collisional narrowing. For these lines, the n parameter of the temperature dependence has been determined.

  13. A study of temperature coefficients of reactivity for a Savannah River Site tritium-producing charge

    International Nuclear Information System (INIS)

    Temperature coefficients of reactivity have been calculated for the Mark 22 assembly in the K-14 charge at the Savannah River Site. Temperature coefficients are the most important reactivity feedback mechanism in SRS reactors; they are used in all safety analyses performed in support of the Safety Analysis Report, and in operations to predict reactivity changes with control rod moves. The effects of the radial location of the assembly in the reactor, isotope depletion, and thermal expansion of the metal components on the temperature coefficients have also been investigated. With the exception of the dead space coefficient, all of the regional temperature coefficients were found to be negative or zero. All of the temperature coefficients become more negative with isotopic depletion over the fuel cycle. Coefficients also become more negative with increasing radial distance of the assembly from the center of the core; this is proven from first principles and confirmed by calculations. It was found that axial and radial thermal expansion effects on the metal fuel and target tubes counteract one another, indicating these effects do not need to be considered in future temperature coefficient calculations for the Mark 22 assembly. The moderator coefficient was found to be nonlinear with temperature; thus, the values derived for accidents involving increases in moderator temperature are significantly different than those for decreases in moderator temperature, although the moderator coefficient is always negative

  14. Evaluation of reactivity coefficients for High Temperature Engineering Test Reactor (HTTR)

    International Nuclear Information System (INIS)

    This report presents the evaluation methods and evaluated results of doppler-, moderator temperature- and power coefficients for High Temperature Engineering Test Reactor (HTTR). From this study, it was made clear that the HTTR possesses inherent power-suppressing feed back characteristic due to the negative power coefficient though the moderator temperature coefficient is slightly positive due to the accumulated isotopes 135Xe and 239Pu. (author)

  15. The investigation of the zero temperature coefficient point of power MOSFET

    Science.gov (United States)

    Bowen, Zhang; Xiaoling, Zhang; Wenwen, Xiong; Shuojie, She; Xuesong, Xie

    2016-06-01

    The paper investigates the zero temperature coefficient (ZTC) point of power MOSFET, based on the output characteristic of power MOSFET, the temperature coefficient of threshold voltage and the carrier mobility. It is found that the gate voltage has a big effect on the ZTC point. The result indicates that there are three types of temperature coefficient under different gate voltage. When the gate voltage is near the threshold voltage, both the linear region and saturation region shows a large positive temperature coefficient. With the increase of gate voltage, the temperature coefficient of the linear region changes from positive to negative, when the saturation region still remains positive, giving rise to the ZTC point. When the gate voltage is high enough, the negative temperature coefficient is present on both the linear and saturation region, resulting in no ZTC point. According to the experimental result, the change of ZTC point as a function of temperature is larger when the gate voltage is higher. The carrier mobility is also discussed, displaying a positive temperature coefficient at low gate voltage due to the free charge screen effect.

  16. Determination of the temperature coefficients and the kinetic parameters for the HTTR safety analysis

    International Nuclear Information System (INIS)

    This report describes the calculational methods which were employed to determine the temperature coefficients and the kinetic parameters for the safety analysis in the HTTR (High Temperature Engineering Test Reactor). The temperature coefficients (doppler, moderator temperature) and the kinetic parameters (prompt neutron life time; l, effective delayed neutron fraction; β eff) are important for the point model core dynamic analysis and should be evaluated properly. The temperature coefficients were calculated by the whole core model. Doppler coefficient was evaluated under the conditions of all control rods withdrawn and the uniform change of fuel temperature. The minimum and the maximum value of the evaluated doppler coefficients in a burnup cycle are -4.6x10-5 and -1.5x10-5 ΔK/K/deg. C respectively. The moderator temperature coefficient was evaluated under the conditions of all control rods withdrawn and the uniform change of moderator temperature. The minimum and the maximum value of the evaluated moderator temperature coefficients in a burnup cycle are -17.1x10-5 and 0.99x10-5ΔK/K/deg. C respectively. In spite of positive moderator temperature coefficient, the power coefficient is always negative. Therefore the HTTR possesses inherent power-suppressing feed back characteristic in all operating condition. We surveyed the effects of the Xe existence, the control rods existence, the fuel temperature and the region in which the temperature was changed on the moderator temperature coefficients. The kinetic parameters were calculated by the perturbation method with the whole core model. The minimum and the maximum value of the evaluated effective delayed neutron fraction (β eff) are 0.0047 and 0.0065 respectively. These of the evaluated prompt neutron life time (l) are 0.67 and 0.78 ms respectively. We have surveyed the effects of the fuel depletion and the core power level on these parameters, and considered these effects on the kinetic parameters. From above

  17. Intermediate Valence Tuning and Seebeck Coefficient Optimization in Yb-based Low-Temperature Thermoelectric Materials

    Science.gov (United States)

    Lehr, Gloria; Morelli, Donald; Jin, Hyungyu; Heremans, Joseph

    2014-03-01

    Several Yb-based intermediate valence compounds have unique thermoelectric properties at low temperatures. These materials are interesting to study for niche applications such as cryogenic Peltier cooling of infrared sensors on satellites. Elements of different sizes, which form isostructural compounds, are used to form solid solutions creating a chemical pressure (smaller atoms - Sc) or relaxation (larger atoms - La) to alter the volume of the unit cell and thereby manipulate the average Yb valence. Magnetic susceptibility measurements show a strong correlation between the Seebeck coefficient and the ratio of trivalent to divalent Yb in these compounds. Two different Yb-based solid solution systems, Yb1-xScxAl2 and Yb1-xLaxCu2Si2, demonstrate that the concentration of Yb can be used to tune both the magnitude of the Seebeck coefficient as well as the temperature at which its absolute maximum occurs. This work is supported by Michigan State University and AFOSR-MURI ``Cryogenic Peltier Cooling'' Contract #FA9550-10-1-0533.

  18. Calculation of the moderator temperature coefficient of reactivity for miniature neutron source reactors

    International Nuclear Information System (INIS)

    This paper presents results of the evaluated group constants for fuel and other important materials of the Miniature Neutron Source Reactor (Mnr) and the moderator temperature coefficient of reactivity through global reactor calculation. In this study the group constants were calculated with the WIMSD code and the global reactor calculation is accomplished by the CITATION code. This work also presents a method for evaluation of the moderator temperature coefficient of reactivity at different temperatures and it's average value in a range of temperature directly through the values of moderator temperature for MNSRs. This method provides simple analytical representation convenient for reactor kinetics calculation and reactor safety assessment. (author)

  19. Temperature Increase Dependence on Ultrasound Attenuation Coefficient in Innovative Tissue-mimicking Materials

    Science.gov (United States)

    Cuccaro, R.; Magnetto, C.; Albo, P. A. Giuliano; Troia, A.; Lago, S.

    Although high intensity focused ultrasound beams (HIFU) have found rapid agreement in clinical environment as a tool for non invasive surgical ablation and controlled destruction of cancer cells, some aspects related to the interaction of ultrasonic waves with tissues, such as the conversion of acoustic energy into heat, are not thoroughly understood. In this work, innovative tissue-mimicking materials (TMMs), based on Agar and zinc acetate, have been used to conduct investigations in order to determine a relation between the sample attenuation coefficient and its temperature increase measured in the focus region when exposed to an HIFU beam. An empirical relation has been deduced establishing useful basis for further processes of validations of numerical models to be adopted for customizing therapeutic treatments.

  20. Reactivity temperature coefficient evaluation of uranium zirconium hydride fuel element in power reactor

    International Nuclear Information System (INIS)

    Highlights: ► We develop an in-core fuel management code package for uranium zirconium hydride power reactor. ► The influence of changes on U–ZrHx fuel element is calculated and analyzed theoretically. ► Increased uranium contents in U–ZrHx reduce prompt negative temperature coefficient markedly. ► Additional poison erbium makes prompt negative temperature coefficient much more negative. ► The characteristics of inherent safety of U–ZrHx core can be retained in power reactors. -- Abstract: An in-core fuel management code package for uranium zirconium hydride power reactor, which is developed on the basis of the assembly lattice code TPFAP and the core calculating code BMFGD for LWR, is firstly introduced in this paper. The inherent safety of the U–ZrHx element which is mainly caused by the high prompt negative temperature coefficient is then evaluated, because the weight percentage of uranium, fuel rod radius and fuel temperature of U–ZrHx element will be different in power reactor from those in research reactor, and these changes may make obvious effect on the prompt negative temperature coefficient. The influence of weight percentage of uranium, fuel rod radius, fuel temperature, content of hydrogen and additional poison on prompt negative temperature coefficient for uranium zirconium hydride element are calculated respectively in this paper, and then the results are analyzed theoretically. The study shows that the absolute value of prompt negative temperature coefficient reduces observably along with the increasing of Uranium weight percentage from 10 wt% in research reactor to maximum 45 wt% in power reactor. Smaller radius, higher operating temperature and longer core life make little effect on the prompt negative temperature coefficient in the condition of high weight percentage of U. Additional poison erbium in fuel makes prompt negative temperature coefficient much more negative. Anyway, high prompt negative temperature coefficient can

  1. Measurement of the power and temperature reactivity coefficients of the RTP TRIGA reactor

    Energy Technology Data Exchange (ETDEWEB)

    Rabir, Mohamad Hairie, E-mail: m_hairie@nuclearmalaysia.gov.my

    2013-12-15

    This paper presents the experimental results of the power and temperature coefficients of reactivity of the RTP TRIGA reactor at the Malaysian Nuclear Agency. The power coefficient of reactivity obtained was approximately −0.26 ¢ kW{sup −1} (−1.81 × 10{sup −5} kW{sup –1}), and the measured temperature reactivity coefficient of the reactor was −0.82 ¢ °C{sup −1} (−5.77 × 10{sup −5} °C{sup −1}) and −1.15 ¢ °C{sup −1} (−8.08 × 10{sup −5} °C{sup −1}) in IFE C12 and IFE F16, respectively. The power defect, which is the change in reactivity taking place between zero power and the power of 850 kW was ∼2.19 $. Because of the negative temperature coefficient, a significant amount of reactivity is needed to compensate for the temperature change and allows the reactor to operate at the higher power levels in steady state. Throughout this experiment, it is the temperature of the fuel that was measured, not the isothermal temperature coefficient (ITC), which comprises both moderator and fuel.

  2. A study of the irradiation temperature coefficient for L-alanine and DL-alanine dosemeters

    International Nuclear Information System (INIS)

    Alanine dosimetry is now well established both as a reference and routine dosemeter for industrial irradiation processing. Accurate dosimetry under the relatively harsh conditions of industrial processing requires a characterisation of the parameters that influence the dosemeter response. The temperature of the dosemeter during irradiation is a difficult quantity to measure so that the accuracy of the temperature coefficient that governs the dosemeter response becomes a critical factor. Numerous publications have reported temperature coefficients for several types of alanine dosemeters. The observed differences in the measured values were commonly attributed to the differences in the polymer binder or the experimental design of the measurement. However, the data demonstrated a consistent difference in the temperature coefficients between L-alanine and DL-alanine. Since there were no commonalities in the dosemeter composition or the measurement methods applied, a clear conclusion is not possible. To resolve this issue, the two isomeric forms of alanine dosemeters were prepared and irradiated in an identical manner. The results indicated that the DL-alanine temperature coefficient is more than 50% higher than the L-alanine temperature coefficient. (authors)

  3. Metastable Changes to the Temperature Coefficients of Thin-Film Photovoltaic Modules

    Energy Technology Data Exchange (ETDEWEB)

    Deceglie, M. G.; Silverman, T. J.; Marion, B.; Kurtz, S. R.

    2014-07-01

    Transient changes in the performance of thin-film modules with light exposure are a well-known and widely reported phenomenon. These changes are often the result of reversible metastabilities rather than irreversible changes. Here we consider how these metastable changes affect the temperature dependence of photovoltaic performance. We find that in CIGS modules exhibiting a metastable increase in performance with light exposure, the light exposure also induces an increase in the magnitude of the temperature coefficient. It is important to understand such changes when characterizing temperature coefficients and when analyzing the outdoor performance of newly installed modules.

  4. The Joint Toxicity of Different Temperature Coefficient Insecticides on Apolygus lucorum (Hemiptera: Miridae).

    Science.gov (United States)

    Liu, Jia; Lincoln, Tamra; An, Jingjie; Gao, Zhanlin; Dang, Zhihong; Pan, Wenliang; Li, Yaofa

    2016-08-01

    The effect of temperature on the cotoxicity coefficient (CTC) value was used to evaluate mixture efficacy of different temperature coefficient chemicals from 15 to 35°C by exposing third-instar Apolygus lucorum (Meyer-Dür) to dip-treated asparagus bean pods. The results indicated the joint toxicity of same temperature coefficient insecticide (TCI) types were unaffected by temperature. This means that even when temperatures change, the mixture ratios of the highest CTC values remained the same, and the effect of temperature on the joint toxicity of same TCI types was only on the CTC values. However, the effect of temperature was variable when considering the joint toxicity of different TCI types. The effect of temperature on the joint toxicity of both strong positive and strong negative TCI types was clear, and the highest CTC values of mixture ratios changed with temperature regularly. When comparing the influence of temperature between strong/slight positive/negative insecticides, the results indicated a greater influence of the strong TCI. Paradoxically, the highest CTC value of the imidacloprid and methomyl mixture did not change with temperature changes consistently, even with the variance of imidacloprid ratios, a strong TCI. These results will guide pest managers in choosing the most effective insecticide mixtures for A. lucorum control under given environmental conditions. PMID:27190041

  5. Temperature effects on diffusion coefficient for 6-gingerol and 6-shogaol in subcritical water extraction

    International Nuclear Information System (INIS)

    6-gingerol and 6-shogaol are the main constituents as anti-inflammatory or bioactive compounds from zingiber officinale Roscoe. These bioactive compounds have been proven for inflammatory disease, antioxidatives and anticancer. The effect of temperature on diffusion coefficient for 6-gingerol and 6-shogaol were studied in subcritical water extraction. The diffusion coefficient was determined by Fick's second law. By neglecting external mass transfer and solid particle in spherical form, a linear portion of Ln (1-(Ct/Co)) versus time was plotted in determining the diffusion coefficient. 6-gingerol obtained the higher yield at 130°C with diffusion coefficient of 8.582x10−11 m2/s whilst for 6-shogaol, the higher yield and diffusion coefficient at 170°C and 19.417 × 10−11 m2/s.

  6. Temperature effects on diffusion coefficient for 6-gingerol and 6-shogaol in subcritical water extraction

    Science.gov (United States)

    Ilia Anisa, Nor; Azian, Noor; Sharizan, Mohd; Iwai, Yoshio

    2014-04-01

    6-gingerol and 6-shogaol are the main constituents as anti-inflammatory or bioactive compounds from zingiber officinale Roscoe. These bioactive compounds have been proven for inflammatory disease, antioxidatives and anticancer. The effect of temperature on diffusion coefficient for 6-gingerol and 6-shogaol were studied in subcritical water extraction. The diffusion coefficient was determined by Fick's second law. By neglecting external mass transfer and solid particle in spherical form, a linear portion of Ln (1-(Ct/Co)) versus time was plotted in determining the diffusion coefficient. 6-gingerol obtained the higher yield at 130°C with diffusion coefficient of 8.582x10-11 m2/s whilst for 6-shogaol, the higher yield and diffusion coefficient at 170°C and 19.417 × 10-11 m2/s.

  7. CH3Cl self-broadening coefficients and their temperature dependence

    International Nuclear Information System (INIS)

    CH335Cl self-broadening coefficients at various temperatures of atmospheric interest are computed by a semi-empirical method particularly suitable for molecular systems with strong dipole–dipole interactions. In order to probe the dependence on the rotational number K, the model parameters are adjusted on extensive room-temperature measurements for K≤7 and allow reproducing fine features of J-dependences observed for K≤3; for higher K up to 20, the fitting is performed on specially calculated semi-classical values. The temperature exponents for the standard power law are extracted and validated by calculation of low-temperature self-broadening coefficients comparing very favorably with available experimental data. An extensive line-list of self-broadening coefficients at the reference temperature 296 K and associated temperature exponents for 0≤J≤70, 0≤K≤20 is provided as Supplementary material for their use in atmospheric applications and spectroscopic databases. -- Highlights: • We calculated methyl chloride self-broadening coefficients using two methods. • Rotational quantum numbers were J from 0 till 70 and K from 0 till 20. • The temperature exponents were calculated for every mentioned line

  8. The accommodation coefficient of the liquid at temperatures below the boiling

    OpenAIRE

    Bulba Elena E.

    2015-01-01

    Are carried out experimental investigation of the laws of vaporization at temperatures below the boiling point. Is determined the mass rate of evaporation of distilled water in large intervals of time at different temperatures in order to sound conclusions about the stationarity of the process of evaporation of the liquid in the conditions of the experiments performed, and also studied the effect of temperature on the rate of evaporation. Accommodation coefficient is defined in the mathematic...

  9. Positive temperature coefficient of magnetic anisotropy in polyvinylidene fluoride (PVDF)-based magnetic composites

    OpenAIRE

    Yiwei Liu; Baomin Wang; Qingfeng Zhan; Zhenhua Tang; Huali Yang; Gang Liu; Zhenghu Zuo; Xiaoshan Zhang; Yali Xie; Xiaojian Zhu; Bin Chen; Junling Wang; Run-Wei Li

    2014-01-01

    The magnetic anisotropy is decreased with increasing temperature in normal magnetic materials, which is harmful to the thermal stability of magnetic devices. Here, we report the realization of positive temperature coefficient of magnetic anisotropy in a novel composite combining β-phase polyvinylidene fluoride (PVDF) with magnetostrictive materials (magnetostrictive film/PVDF bilayer structure). We ascribe the enhanced magnetic anisotropy of the magnetic film at elevated temperature to the st...

  10. Pressure and temperature dependence of viscosity and diffusion coefficients of a glassy binary mixture

    OpenAIRE

    Mukherjee, Arnab; Bhattacharyya, Sarika; Bagchi, Biman

    2002-01-01

    Extensive isothermal-isobaric (NPT) molecular dynamics simulations at many different temperatures and pressures have been carried out in the well-known Kob-Andersen binary mixture model to monitor the effect of pressure (P) and temperature (T) on the dynamic properties such as the viscosity (\\eta) and the self-diffusion (Di) coefficients of the binary system. The following results have been obtained: (i) Compared to temperature, pressure is found to have a weaker effect on the dynamical prope...

  11. The effect of different solar simulators on the measurement of short-circuit current temperature coefficients

    Science.gov (United States)

    Curtis, H. B.; Hart, R. E., Jr.

    1982-01-01

    Gallium arsenide solar cells are considered for several high temperature missions in space. Both near-Sun and concentrator missions could involve cell temperatures on the order of 200 C. Performance measurements of cells at elevated temperatures are usually made using simulated sunlight and a matched reference cell. Due to the change in bandgap with increasing temperature at portions of the spectrum where considerable simulated irradiance is present, there are significant differences in measured short circuit current at elevated temperatures among different simulators. To illustrate this, both experimental and theoretical data are presented for gallium arsenide cells.

  12. Temperature coefficients for in vivo RL and OSL dosimetry using Al2O3:C

    International Nuclear Information System (INIS)

    A radiotherapy dosimetry system based on radioluminescence (RL) and optically stimulated luminescence (OSL) from small carbon-doped aluminum oxide (Al2O3:C) crystals attached to optical-fiber cables has been developed. To quantify the influence of temperature variations on clinical RL and OSL measurement results, we conducted an automated laboratory experiment involving threefold randomization of (1) irradiation temperature (10-45 deg. C) , (2) stimulation temperature (10-45 deg. C), and (3) irradiation dose (0-4 Gy; 50 kV X-rays). We derived linear RL and OSL temperature coefficients using a simple statistical model fitted to all data (N=909). The study shows that the temperature coefficients are independent of dose and other variables studied. In agreement with an earlier investigation, we found that the RL signal changes only with irradiation temperature whereas the OSL response changes with both irradiation temperature, stimulation temperature, and OSL integration time. Typically, the temperature coefficients are of the order of 0.2%/K, and these thermal effects are therefore large enough to be of importance for clinical measurements

  13. Simultaneous retrieval of temperature-dependent absorption coefficient and conductivity of participating media

    Science.gov (United States)

    Ren, Yatao; Qi, Hong; Zhao, Fangzhou; Ruan, Liming; Tan, Heping

    2016-02-01

    A secondary optimization technique was proposed to estimate the temperature-dependent thermal conductivity and absorption coefficient. In the proposed method, the stochastic particle swarm optimization was applied to solve the inverse problem. The coupled radiation and conduction problem was solved in a 1D absorbing, emitting, but non-scattering slab exposed to a pulse laser. It is found that in the coupled radiation and conduction problem, the temperature response is highly sensitive to conductivity but slightly sensitive to the optical properties. On the contrary, the radiative intensity is highly sensitive to optical properties but slightly sensitive to thermal conductivity. Therefore, the optical and thermal signals should both be considered in the inverse problem to estimate the temperature-dependent properties of the transparent media. On this basis, the temperature-dependent thermal conductivity and absorption coefficient were both estimated accurately by measuring the time-dependent temperature, and radiative response at the boundary of the slab.

  14. The effective lifetime and temperature coefficient in a coupled fast-thermal reactor

    International Nuclear Information System (INIS)

    The theory of coupled systems was extensively developed by Avery and co-workers at the Argonne National Laboratory. One of the main points of interest in a coupled system is the larger effective lifetime of neutrons. The effect of the thermal component acts as a sort of neutron-delayer. As in the theory of delayed neutrons the delaying effect disappears if the reactivity worth is high enough to make the fast component critical by itself. In the study a coupled reactor is considered where the fast component suffers a sudden reactivity step α0. Because of the increasing power-level the temperature rises and two temperature coefficients start to work: the temperature coefficient of the fast component and the temperature coefficient of the thermal component. The problem is considered with one group of delayed neutrons (in the ordinary meaning). A formalism is given to express the effective lifetime and temperature coefficient during the different stages of the excursion. Excursions for different α0 are given so that the limit of fast-reactor kinetics is reached. (author)

  15. Control rod position and temperature coefficients in HTTR power-rise tests. Interim report

    International Nuclear Information System (INIS)

    Power-rise tests of the High Temperature Engineering Test Reactor (HTTR) have been carried out aiming to achieve 100% power. So far, 50% of power operation and many tests have been carried out. In the HTTR, temperature change in core is so large to achieve the outlet coolant temperature of 950degC. To improve the calculation accuracy of the HTTR reactor physics characteristics, control rod positions at criticality and temperature coefficients were measured at each step to achieve 50% power level. The calculations were carried out using Monte Carlo code and diffusion theory with temperature distributions in the core obtained by reciprocal calculation of thermo-hydraulic code and diffusion theory. Control rod positions and temperature coefficients were calculated by diffusion theory and Monte Carlo method. The test results were compared to calculation results. The control rod positions at criticality showed good agreement with calculation results by Monte Carlo method with error of 50 mm. The control position at criticality at 100% was predicted around 2900mm. Temperature coefficients showed good agreement with calculation results by diffusion theory. The improvement of calculation will be carried out comparing the measured results up to 100% power level. (author)

  16. Temperature and current coefficients of lasing wavelength in tunable diode laser spectroscopy

    OpenAIRE

    Fukuda, M; Mishima, T.; Nakayama, N.; Masuda, T

    2010-01-01

    The factors determining temperature and current coefficients of lasing wavelength are investigated and discussed under monitoring CO2-gas absorption spectra. The diffusion rate of Joule heating at the active layer to the surrounding region is observed by monitoring the change in the junction voltage, which is a function of temperature and the wavelength (frequency) deviation under sinusoidal current modulation. Based on the experimental results, the time interval of monitoring the wavelength ...

  17. Wilson Coefficients in the Operator Product Expansion of Scalar Currents at Finite Temperature

    OpenAIRE

    Veliev, Elsen Veli; Aliev, Takhmassib M.

    2008-01-01

    In this paper, we investigate operator product expansion for thermal correlation function of the two scalar currents. Due to breakdown of Lorentz invariance at finite temperature, more operators of the same dimension appear in the operator product expansion than at zero temperature. We calculated Wilson coefficients in the short distance expansion and obtain operator product expansion for thermal correlation function in terms of quark condensate, gluon condensate, quark energy density and glu...

  18. On the Navier-Stokes equations with temperature-dependent transport coefficients

    Directory of Open Access Journals (Sweden)

    Josef Málek

    2006-07-01

    Full Text Available We establish long-time and large-data existence of a weak solution to the problem describing three-dimensional unsteady flows of an incompressible fluid, where the viscosity and heat-conductivity coefficients vary with the temperature. The approach reposes on considering the equation for the total energy rather than the equation for the temperature. We consider the spatially periodic problem.

  19. Thermo-optic coefficient dependent temperature sensitivity of FBG-in-SMS based sensor

    Science.gov (United States)

    Chai, Quan; Zhang, JianZhong; Yang, Jun; Canning, John; Peng, GangDing; Chen, YuJin; Yuan, LiBo

    2015-09-01

    Fiber Bragg grating in single-multi-single mode fiber structure (FBG-in-SMS) is proposed to be used as a sensor. It could realize temperature and strain measurement simultaneously because of the different responses of the different parts of the FBG-in-SMS transmission spectrum. The temperature response is decided by the thermo-optic coefficient of the multimode fiber mainly, which is focused on especially in order to optimize its performance.

  20. The Henry's law coefficient of 2-nitrophenol over the temperature range 278–303 K

    OpenAIRE

    Heal, Mathew R.

    2001-01-01

    Although 2-nitrophenol has been identified as an important environmental chemical there is scarcity in the literature regarding the temperature dependence of its Henry's law coefficient, H. Here a bubble purge method was used to measure H for 2- nitrophenol over the temperature range 278–303 K. A novel approach in the data treatment allowed correction of the data for non-equilibrium partitioning in the apparatus to obtain the true equilibrium H value. The experimentally derived...

  1. Low temperature FIR and submm mass absorption coefficient of interstellar silicate dust analogues

    OpenAIRE

    Coupeaud, A.; Demyk, K.; Meny, C.; Nayral, C; Delpech, F.; Leroux, H.; Depecker, C.; Creff, G.; Brubach, J. B.; Roy, P.

    2011-01-01

    Cold dust grains emission in the FIR/submm is usually expressed as a modified black body law in which the dust mass absorption coefficient (MAC), is described with a temperature- and wavelength-independent emissivity spectral index, beta. However, numerous data from space and balloon-born missions and recently from Herschel and Planck show that dust emission is not well understood, as revealed by the observed anti-correlation of beta with the grain temperature. In order to give astronomers th...

  2. Chaotic Temperatures vs Coefficients of Thermodynamic Activity The Advantage of the Method of Chemical Dynamics

    CERN Document Server

    Zilbergleyt, B

    2002-01-01

    The article compares traditional coefficients of thermodynamic activity as a parameter related to individual chemical species to newly introduced reduced chaotic temperatures as system characteristics, both regarding their usage in thermodynamic simulation of open chemical systems. Logical and mathematical backgrounds of both approaches are discussed. It is shown that usage of reduced chaotic temperatures and the Method of Chemical Dynamics to calculate chemical and phase composition in open chemical systems is much less costly, easier to perform and potentially leads to better precision.

  3. Measuring temperature coefficient of TRIGA MARK I reactor by noise analysis

    International Nuclear Information System (INIS)

    The transfer function of TRIGA MARK I Reactor is measured at power zero (5w) and power 118Kw, in the frequency range of 0.02 to 0.5 rd/s. The method of intercorrelation between a pseudostochasticbinary signal is used. A simple dynamic model of the reactor is developed and the coefficient of temperature is estimated

  4. An apparatus for high temperature measurement of the resistivity and Hall coefficient

    DEFF Research Database (Denmark)

    Borup, Kasper Andersen; Toberer, Eric; Snyder, G Jeffrey;

    Two instruments implementing the van der Pauw (VDP) method for measuring the specific resistivity and Hall coefficient at high temperatures are described. Several features to minimize the measurement errors are proposed and some of the advantages compared with traditional six-probe combined...

  5. The Variation of Electrochemical Cell Potentials with Temperature

    Science.gov (United States)

    Peckham, Gavin D.; McNaught, Ian J.

    2011-01-01

    Electrochemical cell potentials have no simple relationship with temperature but depend on the interplay between the sign and magnitude of the isothermal temperature coefficient, dE[degrees]/dT, and on the magnitude of the reaction quotient, Q. The variations in possible responses of standard and non-standard cell potentials to changes in the…

  6. Estimation of Pressure Index and Temperature Sensitivity Coefficient of Solid Rocket Propellants by Static Evaluation

    Directory of Open Access Journals (Sweden)

    Himanshu Shekhar

    2009-11-01

    Full Text Available Burning rate of a solid rocket propellant depends on pressure and temperature. Conventional strand burner and Crawford bomb test on propellant strands was conducted to assess these dependent parameters. However, behaviour of propellant in rocket motor is different from its behaviour in strand form. To overcome this anomaly, data from static evaluation of rocket motor was directly used for assessment of these burningrate controlling parameters. The conventional empirical power law (r=aoexp[p{T-To}]Pn was considered and a method was evolved for determination of pressure index (n and temperature sensitivity coefficient (p of burning rate for solid rocket propellants from static evaluation data. Effect of pressure index and temperature sensitivity coefficient on firing curve is also depicted. Propellant grain was fired in progressive mode to cover a very wide pressure range of 50 kg/cm2 to 250 kg/cm2 and propellant burning rate index was calculated to be 0.32 in the given pressure range. Propellant grain was fired at +35 °C and –20 °C temperatures and temperature sensitivity coefficient of burning rate was calculated to be 0.27 % per °C. Since both the values were evaluated from realised static evaluation curves, these are more realistic and accurate compared to data generated by conventional methods.Defence Science Journal, 2009, 59(6, pp.666-669, DOI:http://dx.doi.org/10.14429/dsj.59.1573

  7. Estimation of Water Diffusion Coefficient into Polycarbonate at Different Temperatures Using Numerical Simulation

    DEFF Research Database (Denmark)

    Shojaee Nasirabadi, Parizad; Jabbaribehnam, Mirmasoud; Hattel, Jesper Henri

    2016-01-01

    Nowadays, many electronic systems are exposed to harsh conditions of relative humidity and temperature. Masstransport properties of electronic packaging materials are needed in order to investigate the influence of moisture andtemperature on reliability of electronic devices. Polycarbonate (PC) is...... widely used in the electronics industry. Thus, in this work the water diffusion coefficient into PC is investigated. Furthermore, numerical methods used for estimation of the diffusion coefficient and their assumptions are discussed. 1D and 3D numerical solutions are compared and based on this, itis...

  8. Calculation of an axial temperature distribution using the reflection coefficient of an acoustic wave.

    Science.gov (United States)

    Červenka, Milan; Bednařík, Michal

    2015-10-01

    This work verifies the idea that in principle it is possible to reconstruct axial temperature distribution of fluid employing reflection or transmission of acoustic waves. It is assumed that the fluid is dissipationless and its density and speed of sound vary along the wave propagation direction because of the fluid temperature distribution. A numerical algorithm is proposed allowing for calculation of the temperature distribution on the basis of known frequency characteristics of reflection coefficient modulus. Functionality of the algorithm is illustrated on a few examples, its properties are discussed. PMID:26520344

  9. Temperature dependence of hydrogenated amorphous silicon solar cell performances

    OpenAIRE

    Riesen, Y.; Stuckelberger, M.; Haug, F. -J.; Ballif, C.; N. Wyrsch

    2016-01-01

    Thin-film hydrogenated amorphous silicon solar (a-Si:H) cells are known to have better temperature coefficients than crystalline silicon cells. To investigate whether a-Si:H cells that are optimized for standard conditions (STC) also have the highest energy yield, we measured the temperature and irradiance dependence of the maximum power output (Pmpp), the fill factor (FF), the short-circuit current density (Jsc), and the open-circuit voltage (Voc) for four series of cells fabricated with dif...

  10. Optimization of temperature coefficient and breeding ratio for a graphite-moderated molten salt reactor

    International Nuclear Information System (INIS)

    Highlights: • The temperature feedback coefficient with different moderation ratios for TMSR in thermal neutron region is optimized. • The breeding ratio and doubling time of a thermal TMSR with three different reprocessing schemes are analyzed. • The smaller hexagon size and larger salt fraction with more negative feedback coefficient can better satisfy the safety demands. • A shorter reprocessing time can achieve a better breeding ratio in a thermal TMSR. • The graphite moderator lifespan is compared with other MSRs and discussed. - Abstract: Molten salt reactor (MSR) has fascinating features: inherent safety, no fuel fabrication, online fuel reprocessing, etc. However, the graphite moderated MSR may present positive feedback coefficient which has severe implications for the transient behavior during operation. In this paper, the feedback coefficient and the breeding ratio are optimized based on the fuel-to-graphite ratio variation for a thorium based MSR (TMSR). A certain thermal core with negative feedback coefficient and relative high initial breeding ratio is chosen for the reprocessing scheme analysis. The breeding performances for the TMSR under different online fuel reprocessing efficiencies and frequencies are evaluated and compared with other MSR concepts. The results indicate that the thermal TMSR can get a breeding ratio greater than 1.0 with appropriate reprocessing scheme. The low fissile inventory in thermal TMSR leads to a short doubling time and low transuranic (TRU) inventory. The lifetime of graphite used for the TMSR is also discussed

  11. A rapid compression machine study of the oxidation of propane in the negative temperature coefficient regime

    Energy Technology Data Exchange (ETDEWEB)

    Gallagher, S.M.; Curran, H.J.; Metcalfe, W.K.; Healy, D.; Simmie, J.M. [Combustion Chemistry Centre, National University of Ireland, Galway (Ireland); Bourque, G. [Rolls-Royce Canada, Montreal (Canada)

    2008-04-15

    The oxidation of propane has been studied in the temperature range 680-970 K at compressed gas pressures of 21, 27, and 37 atm and at varying equivalence ratios of 0.5, 1.0, and 2.0. These data are consistent with other experiments presented in the literature for alkane fuels in that, when ignition delay times are plotted as a function of temperature, a characteristic negative coefficient behavior is observed. In addition, these data were simulated using a detailed chemical kinetic model. It was found that qualitatively the model correctly simulated the effect of change in equivalence ratio and pressure, predicting that fuel-rich, high-pressure mixtures ignite fastest, while fuel-lean, low-pressure mixtures ignite slowest. Moreover, reactivity as a function of temperature is well captured, with the model predicting negative temperature coefficient behavior similar to the experiments. Quantitatively the model is faster than experiment for all mixtures at the lowest temperatures (650-750 K) and is also faster than experiment throughout the entire temperature range for fuel-lean mixtures. (author)

  12. Calculation of fuel and moderator temperature coefficients in APR1400 nuclear reactor by MVP code

    International Nuclear Information System (INIS)

    In this project, these fuel and moderator temperature coefficients were calculated in APR1400 nuclear reactor by MVP code. APR1400 is an advanced water pressurized reactor, that was researched and developed by Korea Experts, its electric power is 1400 MW. The neutronics calculations of full core is very important to analysis and assess a reactor. Results of these calculation is input data for thermal-hydraulics calculations, such as fuel and moderator temperature coefficients. These factors describe the self-safety characteristics of nuclear reactor. After obtaining these reactivity parameters, they were used to re-run the thermal hydraulics calculations in LOCA and RIA accidents. These thermal-hydraulics results were used to analysis effects of reactor physics parameters to thermal hydraulics situation in nuclear reactors. (author)

  13. Method for passively compensating for temperature coefficient of gain in silicon photomultipliers and similar devices

    Science.gov (United States)

    McKisson, John E.; Barbosa, Fernando

    2015-09-01

    A method for designing a completely passive bias compensation circuit to stabilize the gain of multiple pixel avalanche photo detector devices. The method includes determining circuitry design and component values to achieve a desired precision of gain stability. The method can be used with any temperature sensitive device with a nominally linear coefficient of voltage dependent parameter that must be stabilized. The circuitry design includes a negative temperature coefficient resistor in thermal contact with the photomultiplier device to provide a varying resistance and a second fixed resistor to form a voltage divider that can be chosen to set the desired slope and intercept for the characteristic with a specific voltage source value. The addition of a third resistor to the divider network provides a solution set for a set of SiPM devices that requires only a single stabilized voltage source value.

  14. Effect of Heat Transfer Coefficient on the Temperature Gradient for Hollow Fiber

    Institute of Scientific and Technical Information of China (English)

    王华平; 余晓蔚; 杨崇倡; 胡学超; 庄毅

    2001-01-01

    The heat transfer coefficient h caused by blowing affects the heat transfer of fiber greatly. Especially,unsymmetrical blowing forms the unsymmetrical temperature gradient on the fiber cross.section. Based on the results of spinning simulation by computer, the changes of heat transfer coefficient on the cross-section along the spinning line and the effects on distributions of temperature gradients were discussedl It is showed that for the spinning simulation of hollow fiber under strong blowing condition, the heat transfer coetticient should bemodified as: h=0.437×10-4[ G/Vρ ( R2/ R2-n2 ) ] -o.333(V2+ 64( VYsin (θ))2)0.167

  15. Temperature dependence of the coefficient of linear thermal expansion of single-crystal SmS

    International Nuclear Information System (INIS)

    The coefficient of linear thermal expansion of single-crystal SmS has been measured in the temperature range 300-850 K by dilatometry and X-ray diffraction. It is shown that the difference in the results obtained by these two methods is due to the heating-induced formation of SmS phases with small lattice parameters (5.62-5.8 A) close to that for the metallic SmS phase

  16. Spectral history effects on moderator temperature coefficient in a Westinghouse PWR

    International Nuclear Information System (INIS)

    The moderator temperature coefficient (MTC) is an important parameter in the transient behavior of pressurized water reactors (PWRs). Currently, most PWRs are required to measure the MTC at beginning of life (BOL) and near end of life (EOL) to confirm that safety analysis assumptions remain valid. The ability to predict MTCs accurately is essential, therefore, to ensure that core designs will operate within the envelope of transient analysis assumptions and that technical specification limits will bound measured MTCs

  17. Evaluation of heat transfer coefficient of tungsten filaments at low pressures and high temperatures

    International Nuclear Information System (INIS)

    The paper presents an experimental method for the evaluation of the heat transfer coefficient of tungsten filaments at low pressures and high temperatures. For this purpose an electrode of a T5 fluorescent lamp was tested under low pressures with simultaneous heating in order to simulate the starting conditions in the lamp. It was placed in a sealed vessel in which the pressure was varied from 1 kM (kilo micron) to 760 kM. The voltage applied to the electrode was in the order of the filament's voltage of the lamp at the normal operation with the ballast during the preheating process. The operating frequency ranged from DC to 50 kHz. The experiment targeted on estimating the temperature of the electrode at the end of the first and the ninth second after initiating the heating process. Next, the heat transfer coefficient was calculated at the specific experimental conditions. A mathematical model based on the results was developed that estimates the heat transfer coefficient. The experiments under different pressures confirm that the filament's temperature strongly depends on the pressure.

  18. Fabrication of Continuous Fire Wire Detection Sensor usingNegative Temperature Coefficient Material

    Directory of Open Access Journals (Sweden)

    M.L. Singla

    2007-05-01

    Full Text Available Manganese-based spinel semiconducting ceramic was mixed with lanthanum oxide powderand the mixture was characterised for the reproducible negative temperature coefficient (NTCof resistance behaviour. The same mixture was used for the fabrication of 15 m long continuousthermal detector.  The addition of La2O3 leads to decrease in thermistor constant and activationenergy values, thus giving freedom to fabricate thermal sensors for various temperatureapplications. A 3 m long continuous thermal detector for application in the temperature range275 - 350 oC was fabricated and later coupled to form a continuous unit of 15 m length.

  19. The effect of core configuration on temperature coefficient of reactivity in IRR-1

    Energy Technology Data Exchange (ETDEWEB)

    Bettan, M.; Silverman, I.; Shapira, M.; Nagler, A. [Soreq Nuclear Research Center, Yavne (Israel)

    1997-08-01

    Experiments designed to measure the effect of coolant moderator temperature on core reactivity in an HEU swimming pool type reactor were performed. The moderator temperature coefficient of reactivity ({alpha}{sub {omega}}) was obtained and found to be different in two core loadings. The measured {alpha}{sub {omega}} of one core loading was {minus}13 pcm/{degrees}C at the temperature range of 23-30{degrees}C. This value of {alpha}{sub {omega}} is comparable to the data published by the IAEA. The {alpha}{sub {omega}} measured in the second core loading was found to be {minus}8 pcm/{degrees}C at the same temperature range. Another phenomenon considered in this study is core behavior during reactivity insertion transient. The results were compared to a core simulation using the Dynamic Simulator for Nuclear Power Plants. It was found that in the second core loading factors other than the moderator temperature influence the core reactivity more than expected. These effects proved to be extremely dependent on core configuration and may in certain core loadings render the reactor`s reactivity coefficient undesirable.

  20. On the temperature dependence of the rate coefficient of formation of C2+ from C + CH+

    Science.gov (United States)

    Rampino, S.; Pastore, M.; Garcia, E.; Pacifici, L.; Laganà, A.

    2016-08-01

    We carry out quasi-classical trajectory calculations for the C + CH+→ C_2^+ + H reaction on an ad hoc computed high-level ab initio potential energy surface. Thermal rate coefficients at the temperatures of relevance in cold interstellar clouds are derived and compared with the assumed, temperature-independent estimates publicly available in kinetic data bases KIDA and UDfA. For a temperature of 10 K the data base value overestimates by a factor of 2 the one obtained by us (thus improperly enhancing the destruction route of CH+ in astrochemical kinetic models) which is seen to double in the temperature range 5-300 K with a sharp increase in the first 50 K. The computed values are fitted via the popular Arrhenius-Kooij formula and best-fitting parameters α = 1.32 × 10-9 cm3 s-1, β = 0.1 and γ = 2.19 K to be included in the online mentioned data bases are provided. Further investigation shows that the temperature dependence of the thermal rate coefficient better conforms to the recently proposed so-called `deformed Arrhenius' law by Aquilanti and Mundim.

  1. IRR-1 moderator temperature coefficient of reactivity at two different core configurations

    International Nuclear Information System (INIS)

    Experiments designed to measure the effect of coolant moderator temperature on core reactivity in an high enrichment uranium swimming pool type reactor were performed. The moderator temperature coefficient of reactivity αw was obtained and found to be different in two core loadings. The measured a.w of one core loading was -13 pcm/degree C at the temperature range of 23-30 degree C. This value of αw is comparable to the data published by the IAEA. The αw measured in the second core loading was found to be -8 pcm/degree C at the same temperature range. The results were used in a core simulation utilizing the Dynamic Simulator for Nuclear Power Plants. (authors). 4 refs., 5 figs

  2. Temperature dependence of photovoltaic cells, modules, and systems

    Energy Technology Data Exchange (ETDEWEB)

    Emery, K.; Burdick, J.; Caiyem, Y. [National Renewable Energy Lab., Golden, CO (United States)] [and others

    1996-05-01

    Photovoltaic (PV) cells and modules are often rated in terms of a set of standard reporting conditions defined by a temperature, spectral irradiance, and total irradiance. Because PV devices operates over a wide range of temperatures and irradiances, the temperature and irradiance related behavior must be known. This paper surveys the temperature dependence of crystalline and thin-film, state-of-the-art, research-size cells, modules, and systems measured by a variety of methods. The various error sources and measurement methods that contribute to cause differences in the temperature coefficient for a given cell or module measured with various methods are discussed.

  3. Two-temperature transport coefficients of SF6-N2 plasma

    Science.gov (United States)

    Yang, Fei; Chen, Zhexin; Wu, Yi; Rong, Mingzhe; Guo, Anxiang; Liu, Zirui; Wang, Chunlin

    2015-10-01

    Sulfur hexafluoride (SF6) is widely adopted in electric power industry, especially in high-voltage circuit breakers and gas-insulated switchgear. However, the use of SF6 is limited by its high liquidation temperature and high global warming potential. Recently, research shows SF6-N2 mixture, which shows environmental friendliness and good electrical properties, may be a feasible substitute for pure SF6. This paper is devoted to the calculation of and transport coefficients of SF6-N2 mixture under both LTE (local thermodynamic equilibrium) and non-LTE condition. The two-temperature mass action law was used to determine the composition. The transport coefficients were calculated by classical Chapman-Enskog method simplified by Devoto. The thermophysical properties are presented for electron temperatures of 300-40 000 K, ratios of electron to heavy species temperature of 1-10 and N2 mole fraction of 0%-100% at atmospheric pressure. The ionization processes under both LTE and non-LTE have been discussed. The results show that deviations from local thermodynamic equilibrium significantly affect the properties of SF6-N2 plasma, especially before the plasma is fully ionized. The different influence of N2 on properties for SF6-N2 plasma in and out of LTE has been found. The results will serve as reliable reference data for computational simulation of the behavior of SF6-N2 plasmas.

  4. Quasiparticle Theory of Transport Coefficients for Hadronic Matter at Finite Temperature and Baryon Density

    CERN Document Server

    Albright, M

    2016-01-01

    We develop a flexible quasiparticle theory of transport coefficients of hot hadronic matter at finite baryon density. We begin with a hadronic quasiparticle model which includes a scalar and a vector mean field. Quasiparticle energies and the mean fields depend on temperature and baryon chemical potential. Starting with the quasiparticle dispersion relation, we derive the Boltzmann equation and use the Chapman-Enskog expansion to derive formulas for the shear and bulk viscosities and thermal conductivity. We obtain both relaxation time approximation formulas and more general integral equations. Throughout the work, we explicitly enforce the Landau-Lifshitz conditions of fit and ensure the theory is thermodynamically self-consistent. The derived formulas should be useful for predicting the transport coefficients of the hadronic phase of matter produced in heavy-ion collisions at the Relativistic Heavy Ion Collider (RHIC) and at other accelerators.

  5. Quasiparticle theory of transport coefficients for hadronic matter at finite temperature and baryon density

    Science.gov (United States)

    Albright, M.; Kapusta, J. I.

    2016-01-01

    We develop a flexible quasiparticle theory of transport coefficients of hot hadronic matter at finite baryon density. We begin with a hadronic quasiparticle model which includes a scalar and a vector mean field. Quasiparticle energies and the mean fields depend on temperature and baryon chemical potential. Starting with the quasiparticle dispersion relation, we derive the Boltzmann equation and use the Chapman-Enskog expansion to derive formulas for the shear and bulk viscosities and thermal conductivity. We obtain both relaxation-time approximation formulas and more general integral equations. Throughout the work, we explicitly enforce the Landau-Lifshitz conditions of fit and ensure the theory is thermodynamically self-consistent. The derived formulas should be useful for predicting the transport coefficients of the hadronic phase of matter produced in heavy-ion collisions at the Relativistic Heavy Ion Collider and at other accelerators.

  6. The Chern-Simons term induced at high temperature and the quantization of its coefficient

    International Nuclear Information System (INIS)

    By perturbative calculations of the high-temperature ground-state axial vector current of fermion fields coupled to gauge fields, an anomalous Chern-Simons topological mass term is induced in the three-dimensional effective action. The anomaly in three dimensions appears just in the ground-state current rather than in the divergence of ground-state current. In the Abelian case, the contribution comes only from the vacuum polarization graph, whereas in the non-Abelian case, contributions come from the vacuum polarization graph and the two triangle graphs. The relation between the quantization of the Chern-Simons coefficient and the Dirac quantization condition of magnetic charge is also obtained. It implies that in a (2+1)-dimensional QED with the Chern-Simons topological mass term and a magnetic monopole with magnetic charge g present, the Chern-Simons coefficient must be also quantized, just as in the non-Abelian case. (orig.)

  7. Method of measuring instant negative temperature coefficient of pulsed reactor by noise techniques

    International Nuclear Information System (INIS)

    Based on the relationship of neutron noise and temperature noise in reactors, a physical model which will be used to calculate the instant negative temperature coefficient (αF) of pulsed reactor is established in frequency domain by noise techniques. The neutron dynamic equation and thermal-dynamic equation were used while constructing the physical model. According to the disturbance in formation of neutron signal and temperature signal in the stable operation situation of reactors, the power spectrum densities are get by auto-regress moving average model. The αF of the pulsed reactor is obtained by best fitting method in the frequency domain. And the results are relative to the theory values

  8. Rate coefficients for the reactions of ions with polar molecules at interstellar temperatures

    International Nuclear Information System (INIS)

    A theory has been developed recently which predicts that the rate coefficients, k, for the reactions of ions with polar molecules at low temperatures will be much greater than the canonical value of 10-9 cm3 s-1. The new theory indicates that k is greatest for low-lying rotational sates and increases rapidly with decreasing temperature. We refer to recent laboratory measurements which validate the theory, present calculated values of k for the reactions of H+3 ions with several polar molecules, and discuss their significance to interstellar chemistry. For the reactions of ions with molecules having large dipole moments, we recommend that k values as large as 10-7 cm3 s-1 should be used in ion-chemical models of low-temperature interstellar clouds

  9. Temperature dependence of the atmospheric photolysis rate coefficient for NO2

    Science.gov (United States)

    Shetter, Richard E.; Davidson, James A.; Cantrell, Christopher A.; Burzysnki, Norbert J., Jr.; Calvert, Jack G.

    1988-01-01

    Accurate values for the photolysis rate coefficient of NO2 (j1) are required for studies related to the observed imbalance in the photostationary state of O3, NO, and NO2 in the troposphere. Direct measurements of the temperature dependence of j1 at temperatures from -70 to 30 C were made in sunlight for relatively cloudless summer days in Boulder, Colorado. The ratios of j1 (30 C)/j1 (T C) for T = -10 C and -70 C, respectively, were 1.046 + or - 0.040 and 1.070 + or - 0.031. The j1 ratios were independent of solar zenith angle. Theoretical estimates of the temperature-dependent j1 ratios based upon recently reported cross section (sigma) and quantum yield (phi) data are more consistent with these experimental measurements than those based upon the currently accepted sigma and phi data.

  10. Graphene-based, mid-infrared, room-temperature pyroelectric bolometers with ultrahigh temperature coefficient of resistance

    CERN Document Server

    Sassi, U; Nanot, S; Bruna, M; Borini, S; Milana, S; De Fazio, D; Zhuang, Z; Lidorikis, E; Koppens, F H L; Ferrari, A C; Colli, A

    2016-01-01

    Graphene is ideally suited for photonic and optoelectronic applications, with a variety of photodetectors (PDs) in the visible, near-infrared (NIR), and THz reported to date, as well as thermal detectors in the mid-infrared (MIR). Here, we present a room temperature-MIR-PD where the pyroelectric response of a LiNbO3 crystal is transduced with high gain (up to 200) into resistivity modulation for graphene, leading to a temperature coefficient of resistance up to 900%/K, two orders of magnitude higher than the state of the art, for a device area of 300x300um2. This is achieved by fabricating a floating metallic structure that concentrates the charge generated by the pyroelectric substrate on the top-gate capacitor of the graphene channel. This allows us to resolve temperature variations down to 15umK at 1 Hz, paving the way for a new generation of detectors for MIR imaging and spectroscopy

  11. Frequency analysis of temperature-dependent interferometric signal for the measurement of the temperature coefficient of refractive index

    Science.gov (United States)

    Zhou, Jianqin; Shen, Jun; Neill, W. Stuart

    2016-07-01

    A method of frequency analysis for the measurement of the temperature coefficient of refractive index (dn/dT) using a Fabry-Perot interferometer was developed and tested against ethanol and water. The temperature-dependent interferometric signal described by Airy's formula was analyzed in both the temperature and frequency domains. By fast Fourier transform, a low-pass filter was designed and employed to eliminate the noise superimposed on the signal. dn/dT was determined accurately from the noise-removed signal by peak analysis. Furthermore, the signal frequency parameters may be utilized for the material thermophysical property characterization. This method lays the foundation for an online dn/dT instrument for monitoring chemical processes.

  12. HIGH TEMPERATURE POLYMER FUEL CELLS

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Qingfeng, Li; He, Ronghuan;

    2003-01-01

    This paper will report recent results from our group on polymer fuel cells (PEMFC) based on the temperature resistant polymer polybenzimidazole (PBI), which allow working temperatures up to 200°C. The membrane has a water drag number near zero and need no water management at all. The high working...

  13. Measurement of the moderator temperature coefficient of reactivity for pressurized water reactors

    International Nuclear Information System (INIS)

    The measurements of the moderator temperature coefficient (MTC) are performed to demonstrate that the calculational model produces results that are consistent with the measurements. Since negative MTC is also a technical specification value that may limit the cycle length, it is important to measure it as accurately as possible. In this report, preferred choice of test method depending on the time in cycle, best power indication and temperature definition in MTC calculation were determined based on the MTC test results taken during initial startup testing and at 2/3 cycle burnup in the Yonggwang nuclear power plant. The results show that the ratio and rodded methods provided good agreement with the predictions during initial startup testing. However, near end-of-cycle the depletion method gives better results, and so is suggested to be used in the MTC measurements at 2/3 cycle burnup. The use of primary Delta T power as a power indicator in the MTC calculations is highly advisable since it responds with good consistent results very quickly to changes unlike secondary calorimetric power. For the appropriate temperature definitions used in the MTC calculations, it is considered that the arithmetic average temperature measured simply by inlet and outlet thermocouples is preferred. Although volumetric average temperature provides better results, the improvement is not sufficient to compensate for the simplicity of calculations by arithmetic average temperature. (author)

  14. Size- and Temperature-Dependent Thermal Expansion Coefficient of a Nanofilm

    Institute of Scientific and Technical Information of China (English)

    ZHOU Li-Jun; GUO Jian-Gang; ZHAO Ya-Pu

    2009-01-01

    The thermal expansion coefficient (TEC) of an ideal crystal is derived by using a method of Boltzmann statistics.The Morse potential energy function is adopted to show the dependence of the TEC on the temperature.By taking the effects of the surface relaxation and the surface energy into consideration,the dimensionless TEC of a nanofilm is derived.It is shown that with decreasing thickness,the TEC can increase or decrease,depending on the surface relaxation of the nanofilm.

  15. Full-potential calculations of the temperature dependence of self-diffusion coefficients: application to Cs

    International Nuclear Information System (INIS)

    The change in slope of the Arrhenius curve for the diffusion coefficient as a function of temperature is discussed and its occurance is explained by vacancies concentration dependence of the formation energy. It is shown that a sign of the mixing energy parameter of the regular solid solution of vacancies in pure metals is closely connected with the sign of the curvature of the diffusion plot. For the analysis of this plot as well as for the estimation of other parameters of self diffusion of bcc Cs we used the total energy calculations based on the Full Potential LMTO method. (orig.)

  16. Determination of Thermal Expansion Coefficients and Locating the Temperature-Induced Phase Transition in Methylammonium Lead Perovskites Using X-ray Diffraction.

    Science.gov (United States)

    Jacobsson, T Jesper; Schwan, L Josef; Ottosson, Mikael; Hagfeldt, Anders; Edvinsson, Tomas

    2015-11-16

    Lead halogen perovskites, and particularly methylammonium lead iodine, CH3NH3PbI3, have recently attracted considerable interest as alternative solar cell materials, and record solar cell efficiencies have now surpassed 20%. Concerns have, however, been raised about the thermal stability of methylammonium lead iodine, and a phase transformation from a tetragonal to a cubic phase has been reported at elevated temperature. Here, this phase transition has been investigated in detail using temperature-dependent X-ray diffraction measurements. The phase transformation is pinpointed to 54 °C, which is well within the normal operating range of a typical solar cell. The cell parameters were extracted as a function of the temperature, from which the thermal expansion coefficient was calculated. The latter was found to be rather high (αv = 1.57 × 10(-4) K(-1)) for both the tetragonal and cubic phases. This is 6 times higher than the thermal expansion coefficient for soda lime glass and CIGS and 11 times larger than that of CdTe. This could potentially be of importance for the mechanical stability of perovskite solar cells in the temperature cycling experienced under normal day-night operation. The experimental knowledge of the thermal expansion coefficients and precise determination of the cell parameters can potentially also be valuable while conducting density functional theory simulations on these systems in order to deliver more accurate band structure calculations. PMID:26457861

  17. Thermocouple error correction for measuring the flame temperature with determination of emissivity and heat transfer coefficient.

    Science.gov (United States)

    Hindasageri, V; Vedula, R P; Prabhu, S V

    2013-02-01

    Temperature measurement by thermocouples is prone to errors due to conduction and radiation losses and therefore has to be corrected for precise measurement. The temperature dependent emissivity of the thermocouple wires is measured by the use of thermal infrared camera. The measured emissivities are found to be 20%-40% lower than the theoretical values predicted from theory of electromagnetism. A transient technique is employed for finding the heat transfer coefficients for the lead wire and the bead of the thermocouple. This method does not require the data of thermal properties and velocity of the burnt gases. The heat transfer coefficients obtained from the present method have an average deviation of 20% from the available heat transfer correlations in literature for non-reacting convective flow over cylinders and spheres. The parametric study of thermocouple error using the numerical code confirmed the existence of a minimum wire length beyond which the conduction loss is a constant minimal. Temperature of premixed methane-air flames stabilised on 16 mm diameter tube burner is measured by three B-type thermocouples of wire diameters: 0.15 mm, 0.30 mm, and 0.60 mm. The measurements are made at three distances from the burner tip (thermocouple tip to burner tip/burner diameter = 2, 4, and 6) at an equivalence ratio of 1 for the tube Reynolds number varying from 1000 to 2200. These measured flame temperatures are corrected by the present numerical procedure, the multi-element method, and the extrapolation method. The flame temperatures estimated by the two-element method and extrapolation method deviate from numerical results within 2.5% and 4%, respectively. PMID:23464237

  18. Thermocouple error correction for measuring the flame temperature with determination of emissivity and heat transfer coefficient

    Science.gov (United States)

    Hindasageri, V.; Vedula, R. P.; Prabhu, S. V.

    2013-02-01

    Temperature measurement by thermocouples is prone to errors due to conduction and radiation losses and therefore has to be corrected for precise measurement. The temperature dependent emissivity of the thermocouple wires is measured by the use of thermal infrared camera. The measured emissivities are found to be 20%-40% lower than the theoretical values predicted from theory of electromagnetism. A transient technique is employed for finding the heat transfer coefficients for the lead wire and the bead of the thermocouple. This method does not require the data of thermal properties and velocity of the burnt gases. The heat transfer coefficients obtained from the present method have an average deviation of 20% from the available heat transfer correlations in literature for non-reacting convective flow over cylinders and spheres. The parametric study of thermocouple error using the numerical code confirmed the existence of a minimum wire length beyond which the conduction loss is a constant minimal. Temperature of premixed methane-air flames stabilised on 16 mm diameter tube burner is measured by three B-type thermocouples of wire diameters: 0.15 mm, 0.30 mm, and 0.60 mm. The measurements are made at three distances from the burner tip (thermocouple tip to burner tip/burner diameter = 2, 4, and 6) at an equivalence ratio of 1 for the tube Reynolds number varying from 1000 to 2200. These measured flame temperatures are corrected by the present numerical procedure, the multi-element method, and the extrapolation method. The flame temperatures estimated by the two-element method and extrapolation method deviate from numerical results within 2.5% and 4%, respectively.

  19. Temperature dependences of N2-broadening and shift coefficients in the ν6 perpendicular band of 12CH3D

    International Nuclear Information System (INIS)

    The temperature-dependences of line broadening and shift parameters for many 12CH3D transitions have been determined using six high-resolution, high signal-to-noise ratio, room-temperature CH3D (98% purity) and CH3D-N2 spectra recorded with 25 cm path length ( at 0.01 cm−1 unapodized resolution) using the McMath−Pierce FTS located on Kitt Peak, Arizona, and 17 additional high quality, pure CH3D (99% purity) and CH3D-N2 spectra recorded between 79 and 296 K with the 20.38 cm path coolable cell (at 0.0056 cm−1 unapodized resolution) with the Bruker 125HR FTS at the Jet Propulsion Laboratory (JPL), Pasadena, California. The spectra have been fitted simultaneously applying a multispectrum nonlinear least-squares technique. In the analysis, the Lorentzian N2-broadened half-width coefficients and the corresponding pressure-shift coefficients as well as their temperature dependences are extracted for about 400 transitions (0≤J″≤19, K″≤16) in the perpendicular (ΔK=±1) ν6 band. At 296 K, the measured N2-broadened half-width coefficients range from 0.0209 to 0.0782 cm−1 atm−1 whereas the majority of the associated N2-induced shift coefficients are negative, and the values are between -0.016 and 0.005 cm−1 atm−1. The temperature dependence exponents for N2-broadened half-widths range between 0.264 and 0.924, whereas the temperature dependence coefficients for N2-induced shifts are between 0 and 0.00011 cm−1 atm−1 K−1. The N2-broadened half-width coefficients have been also calculated using a semi-classical approach based on a rigorous treatment of the active molecule as a symmetric top, a model intermolecular potential comprising both short- and long-range interactions, and exact classical trajectories. The role of the various high-order multipoles in the line-broadening at low, middle and high values of the rotational quantum number J″ has been investigated and the main features of the K-dependences analyzed. The calculations performed for

  20. A method for estimating the diffuse attenuation coefficient (KdPAR)from paired temperature sensors

    Science.gov (United States)

    Read, Jordan S.; Rose, Kevin C.; Winslow, Luke A.; Read, Emily Kara

    2015-01-01

    A new method for estimating the diffuse attenuation coefficient for photosynthetically active radiation (KdPAR) from paired temperature sensors was derived. We show that during cases where the attenuation of penetrating shortwave solar radiation is the dominant source of temperature changes, time series measurements of water temperatures at multiple depths (z1 and z2) are related to one another by a linear scaling factor (a). KdPAR can then be estimated by the simple equation KdPAR ln(a)/(z2/z1). A suggested workflow is presented that outlines procedures for calculating KdPAR according to this paired temperature sensor (PTS) method. This method is best suited for conditions when radiative temperature gains are large relative to physical noise. These conditions occur frequently on water bodies with low wind and/or high KdPARs but can be used for other types of lakes during time periods of low wind and/or where spatially redundant measurements of temperatures are available. The optimal vertical placement of temperature sensors according to a priori knowledge of KdPAR is also described. This information can be used to inform the design of future sensor deployments using the PTS method or for campaigns where characterizing sub-daily changes in temperatures is important. The PTS method provides a novel method to characterize light attenuation in aquatic ecosystems without expensive radiometric equipment or the user subjectivity inherent in Secchi depth measurements. This method also can enable the estimation of KdPAR at higher frequencies than many manual monitoring programs allow.

  1. Low temperature FIR and submm mass absorption coefficient of interstellar silicate dust analogues

    CERN Document Server

    Coupeaud, A; Meny, C; Nayral, C; Delpech, F; Leroux, H; Depecker, C; Creff, G; Brubach, J B; Roy, P

    2011-01-01

    Cold dust grains emission in the FIR/submm is usually expressed as a modified black body law in which the dust mass absorption coefficient (MAC), is described with a temperature- and wavelength-independent emissivity spectral index, beta. However, numerous data from space and balloon-born missions and recently from Herschel and Planck show that dust emission is not well understood, as revealed by the observed anti-correlation of beta with the grain temperature. In order to give astronomers the necessary data to interpret FIR/submm observations, we synthesised analogues of interstellar amorphous and crystalline silicate grains, rich in Mg and Ca, and having stiochiometry of olivine and pyroxene and measured their MAC, in the 100-1000/1500 \\mum range for grain temperatures varying from 300 to 10 K. We find that the grain MAC decreases when the grain temperature decreases and that the local spectral index, beta, defined as the slope of the MAC curve, is anti-correlated with the grain temperature. These variation...

  2. Temperature- and pressure-dependent absorption coefficients for CO2 and O2 at 193 nm

    Science.gov (United States)

    Hartinger, K. T.; Nord, S.; Monkhouse, P. B.

    Absorption of laser radiation at 193 nm by CO2 and O2 was studied at a series of different temperatures up to 1273 K and pressures up to 1 bar. The spectrum for CO2 was found to be broadband, so that absorption could be fitted to a Beer-Lambert law. On the other hand, the corresponding O2 spectrum is strongly structured and parameterisation requires a more complex relation, depending on both temperature and the product (pressure × absorption path length). In this context, the influence of spectral structure on the resulting spectrally integrated absorption coefficients is discussed. Using the fitting parameters obtained, effective transmissions at 193 nm can be calculated for a wide range of experimental conditions. As an illustration of the practical application of these data, the calculation of effective transmission for a typical industrial flue gas is described.

  3. Self-diffusion coefficients for water and organic solvents at high temperatures along the coexistence curve

    Science.gov (United States)

    Yoshida, Ken; Matubayasi, Nobuyuki; Nakahara, Masaru

    2008-12-01

    The self-diffusion coefficients D for water, benzene, and cyclohexane are determined by using the pulsed-field-gradient spin echo method in high-temperature conditions along the liquid branch of the coexistence curve: 30-350 °C (1.0-0.58 g cm-3), 30-250 °C (0.87-0.56 g cm-3), and 30-250 °C (0.77-0.48 g cm-3) for water, benzene, and cyclohexane, respectively. The temperature and density effects are separated and their origins are discussed by examining the diffusion data over a wide range of thermodynamic states. The temperature dependence of the self-diffusion coefficient for water is larger than that for organic solvents due to the large contribution of the attractive hydrogen-bonding interaction in water. The density dependence is larger for organic solvents than for water. The difference is explained in terms of the van der Waals picture that the structure of nonpolar organic solvents is determined by the packing effect due to the repulsion or exclusion volumes. The dynamic solvation shell scheme [K. Yoshida et al., J. Chem. Phys. 127, 174509 (2007)] is applied for the molecular interpretation of the translational dynamics with the aid of molecular dynamics simulation. In water at high temperatures, the velocity relaxation is not completed before the relaxation of the solvation shell (mobile-shell type) as a result of the breakdown of the hydrogen-bonding network. In contrast, the velocity relaxation of benzene is rather confined within the solvation shell (in-shell type).

  4. Two-temperature transport coefficients of SF{sub 6}–N{sub 2} plasma

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Fei; Chen, Zhexin; Wu, Yi, E-mail: wuyic51@mail.xjtu.edu.cn; Rong, Mingzhe; Wang, Chunlin [State Key Laboratory of Electrical Insulation and Power Equipment, School of Electrical Engineering, Xi' an Jiaotong University, Xi' an 710049 (China); Guo, Anxiang; Liu, Zirui [Electric Power Research Institute of State Grid Shaanxi Electric Power Company, Xian (China)

    2015-10-15

    Sulfur hexafluoride (SF{sub 6}) is widely adopted in electric power industry, especially in high-voltage circuit breakers and gas-insulated switchgear. However, the use of SF{sub 6} is limited by its high liquidation temperature and high global warming potential. Recently, research shows SF{sub 6}–N{sub 2} mixture, which shows environmental friendliness and good electrical properties, may be a feasible substitute for pure SF{sub 6}. This paper is devoted to the calculation of and transport coefficients of SF{sub 6}–N{sub 2} mixture under both LTE (local thermodynamic equilibrium) and non-LTE condition. The two–temperature mass action law was used to determine the composition. The transport coefficients were calculated by classical Chapman–Enskog method simplified by Devoto. The thermophysical properties are presented for electron temperatures of 300–40 000 K, ratios of electron to heavy species temperature of 1–10 and N{sub 2} mole fraction of 0%–100% at atmospheric pressure. The ionization processes under both LTE and non-LTE have been discussed. The results show that deviations from local thermodynamic equilibrium significantly affect the properties of SF{sub 6}–N{sub 2} plasma, especially before the plasma is fully ionized. The different influence of N{sub 2} on properties for SF{sub 6}–N{sub 2} plasma in and out of LTE has been found. The results will serve as reliable reference data for computational simulation of the behavior of SF{sub 6}–N{sub 2} plasmas.

  5. Measuring 1HN temperature coefficients in invisible protein states by relaxation dispersion NMR spectroscopy

    International Nuclear Information System (INIS)

    A method based on the Carr-Purcell-Meiboom-Gill relaxation dispersion experiment is presented for measuring the temperature coefficients of amide proton chemical shifts of low populated ‘invisible’ protein states that exchange with a ‘visible’ ground state on the millisecond time-scale. The utility of the approach is demonstrated with an application to an I58D mutant of the Pfl6 Cro protein that undergoes exchange between the native, folded state and a cold denatured, unfolded conformational ensemble that is populated at a level of 6% at 2.5°C. A wide distribution of amide temperature coefficients is measured for the unfolded state. The distribution is centered about –5.6 ppb/K, consistent with an absence of intra-molecular hydrogen bonds, on average. However, the large range of values (standard deviation of 2.1 ppb/K) strongly supports the notion that the unfolded state of the protein is not a true random coil polypeptide chain.

  6. Analysis of Moderator Temperature Reactivity Coefficient of the PWR Core Using WIMS-ANL

    International Nuclear Information System (INIS)

    The Moderator Temperature Reactivity Coefficient (MTRC) is an important parameter in design, control and safety, particularly in PWR reactor. It is then very important to validate any new processed library for an accurate prediction of this parameter. The objective of this work is to validate the newly WIMS library based on ENDF/B-VI nuclear data files, especially for the prediction of the MTRC parameter. For this purpose, it is used a set of light water moderated lattice experiments as the NORA experiment and R1-100H critical reactors, both of reactors using UO2 fuel pellet. Analysis is used with WIMSD/4 lattice code with original cross section libraries and WIMS-ANL with ENDF/B-VI cross section libraries. The results showed that the moderator temperatures reactivity coefficients for the NORA reactor using original libraries is - 5.039E-04 %Δk/k/℃ but for ENDF/B-VI libraries is - 2.925E-03 %Δk/k/℃. Compared to the designed value of the reactor core, the difference is in the range of 1.8 - 3.8 % for ENDF/B-IV libraries. It can be concluded that for reactor safety and control analysis, it has to be used ENDF/B- VI libraries because the original libraries is not accurate any more. (author)

  7. Analytical method for estimating the thermal expansion coefficient of metals at high temperature

    International Nuclear Information System (INIS)

    In this paper, we propose an analytical method for estimating the thermal expansion coefficient (TEC) of metals at high-temperature ranges. Although the conventional method based on quasiharmonic approximation (QHA) shows good results at low temperatures, anharmonic effects caused by large-amplitude thermal vibrations reduces its accuracy at high temperatures. Molecular dynamics (MD) naturally includes the anharmonic effect. However, since the computational cost of MD is relatively high, in order to make an interatomic potential capable of reproducing TEC, an analytical method is essential. In our method, analytical formulation of the radial distribution function (RDF) at finite temperature realizes the estimation of the TEC. Each peak of the RDF is approximated by the Gaussian distribution. The average and variance of the Gaussian distribution are formulated by decomposing the fluctuation of interatomic distance into independent elastic waves. We incorporated two significant anharmonic effects into the method. One is the increase in the averaged interatomic distance caused by large amplitude vibration. The second is the variation in the frequency of elastic waves. As a result, the TECs of fcc and bcc crystals estimated by our method show good agreement with those of MD. Our method enables us to make an interatomic potential that reproduces the TEC at high temperature. We developed the GEAM potential for nickel. The TEC of the fitted potential showed good agreement with experimental data from room temperature to 1000 K. As compared with the original potential, it was found that the third derivative of the wide-range curve was modified, while the zeroth, first and second derivatives were unchanged. This result supports the conventional theory of solid state physics. We believe our analytical method and developed interatomic potential will contribute to future high-temperature material development. (paper)

  8. Intelligent Detector of Internal Combustion Engine Cylinder Pressure and Sensitivity Temperature Coefficient Compensation

    Directory of Open Access Journals (Sweden)

    Beirong Zheng

    2013-01-01

    Full Text Available The detecting device based on mechanical mechanism is far from the measurement of internal combustion engine cylinder explosion and compression pressure. This pressure detection is under the environment of pulsed gas (over 500 times per one minute and mechanical impactive vibration. Piezoresistive detection with silicon on insulator (SOI strain gauges to pressure seems to be a good solution to meet such special applications. In this work, separation by implanted oxygen (SIMOX wafer was used to fabricate the high temperature pressure sensor chip. For high accuracy and wide temperature range application, this paper also presents a novel pressure sensitivity temperature coefficient (TCS compensation method, using integrated constant current network. A quantitative compensation formula is introduced in mathematics. During experiments, the absolute value of the compensated TCS is easy to be 10 × 10−6/°C~100 × 10−6/°C by individual adjustment and calibration of each device’s temperature compensation. Therefore, the feasibility and practicability of this technology are tested. Again, the disadvantages are discussed after the research of the experiment data and the improvement methods are also given in the designing period. This technology exhibits the great potential practical value of internal combustion engine cylinder pressure with volume manufacturing.

  9. Polymorphic Phase Transition and Temperature Coefficient of Capacitance of Alkaline Niobate Based Ceramics

    Directory of Open Access Journals (Sweden)

    In-Ho Im

    2013-04-01

    Full Text Available 0.95(Na0.5K0.5NbO3-0.05BaTiO3 + 0.2wt% Ag2O (hereafter, No excess NKN ceramics and 0.95(Na0.5K0.5NbO3-0.05BaTiO3 + 0.2wt% Ag2O with excess (Na0.5K0.5NbO3 (hereafter, Excess NKN were fabricated by the conventionalsolid state sintering method, and their phase transition properties and dielectric properties were investigated. Thecrystalline structure of No excess NKN ceramics and Excess NKN ceramics were shown characteristics of polymorphicphase transition (hereafter, PPT, especially shift from the orthorhombic to tetragonal phase by increasing sinteringtemperature range from 1,100℃ to 1,200℃. Also, the temperature coefficient of capacitance (hereafter, TCC ofNo excess NKN ceramics and Excess NKN ceramics from -40℃ to 100℃ was measured to evaluate temperaturestability for applications in cold regions. The TCC of No excess NKN and Excess NKN ceramics showed positive TCCcharacteristics at a temperature range from -40℃ to 100℃. Especially, Excess NKN showed a smaller TCC gradientthan those of Excess NKN ceramics in range from -40℃ to 100℃. Therefore, NKN piezoelectric ceramics combinedwith temperature compensated capacitor having negative temperature characteristics is desired for usage in coldregions.

  10. Effect of heat transfer coefficient on sheath and fuel centreline temperatures in SCWRS

    International Nuclear Information System (INIS)

    SuperCritical Water-cooled nuclear Reactors (SCWRs) utilize light water above the pseudocritical point as a reactor coolant. This Generation IV reactor concept is currently in its preliminary design phase. This paper discusses the variables that influence heat transfer from the fuel. The coolant Heat Transfer Coefficient (HTC). Axial Heat Flux Profile (AHFP), sheath (clad) geometry and fuel thermal conductivity all impact the sheath and fuel centreline temperatures. The presented analysis utilizes the most recent HTC correlation developed for supercritical water, the Mokry et al. correlation (2009). The proposed sheath geometry is based on smaller diameter fuel elements than that of the current design to accommodate more fuel rods. Both uniform and cosine AHFPs, at average channel power, are applied. The results presented describe a sensitivity analysis of the effect of incrementing the HTC on sheath and fuel centreline temperatures. With a uniform AHFP and increasing HTC increments from 50 - 200% HTC the average temperature difference compared to 100% HTC are decreases from 13 to -18%. With a cosine AHFP and HTC incremented from 50 - 200% HTC the average temperature difference compared to 100% HTC have the range of 20 to -10%. (author)

  11. Temperature dependence of the rate coefficient for charge exchange of metastable O/+//2D/ with N2. [in atmosphere

    Science.gov (United States)

    Torr, M. R.; Torr, D. G.

    1980-01-01

    Using a data base of aeronomical parameters measured on board the Atmosphere Explorer-C satellite, temperature dependence of the reaction rate coefficient is deduced for the charge exchange of O(+)(2D) with N2. The results indicate the Explorer values determined over the temperature range from 700 to 1900 K are not in conflict with laboratory measurements made at higher temperatures.

  12. HIGH TEMPERATURE POLYMER FUEL CELLS

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Qingfeng, Li; He, Ronghuan; Gang, Xiao; Gao, Ji-An; Bjerrum, Niels

    2003-01-01

    This paper will report recent results from our group on polymer fuel cells (PEMFC) based on the temperature resistant polymer polybenzimidazole (PBI), which allow working temperatures up to 200°C. The membrane has a water drag number near zero and need no water management at all. The high working...... temperature allows for utilization of the excess heat for fuel processing. Moreover, it provides an excellent CO tolerance of several percent, and the system needs no purification of hydrogen from a reformer. Continuous service for over 6 months at 150°C has been demonstrated....

  13. OSMOTIC COEFFICIENTS, SOLUBILITIES, AND DELIQUESCENCE RELATIONS IN MIXED AQUEOUS SALT SOLUTIONS AT ELEVATED TEMPERATURE

    International Nuclear Information System (INIS)

    While thermodynamic properties of pure aqueous electrolytes are relatively well known at ambient temperature, there are far fewer data for binary systems extending to elevated temperatures and high concentrations. There is no general theoretically sound basis for prediction of the temperature dependence of ionic activities, and consequently temperature extrapolations based on ambient temperature data and empirical equations are uncertain and require empirical verification. Thermodynamic properties of mixed brines in a wide range of concentrations would enhance the understanding and precise modeling of the effects of deliquescence of initially dry solids in humid air in geological environments and in modeling the composition of waters during heating, cooling, evaporation or condensation processes. These conditions are of interest in the analysis of waters on metal surfaces at the proposed radioactive waste repository at Yucca Mountain, Nevada. The results obtained in this project will be useful for modeling the long-term evolution of the chemical environment, and this in turn is useful for the analysis of the corrosion of waste packages. In particular, there are few reliable experimental data available on the relationship between relative humidity and composition that reveals the eutonic points of the mixtures and the mixture deliquescence RH. The deliquescence RH for multicomponent mixtures is lower than that of pure component or binary solutions, but is not easy to predict quantitatively since the solutions are highly nonideal. In this work we used the ORNL low-temperature and high-temperature isopiestic facilities, capable of precise measurements of vapor pressure between ambient temperature and 250 C for determination of not only osmotic coefficients, but also solubilities and deliquescence points of aqueous mixed solutions in a range of temperatures. In addition to standard solutions of CaCl2, LiCl, and NaCl used as references, precise direct

  14. Identity period and thermal expansion coefficient of rare earth hexaborides at temperatures of 5-320 K

    International Nuclear Information System (INIS)

    For five compounds of MB6 (M = Ce, Pr, Nd, Gd, Tb) hexaborides one studied experimentally temperature dependences of crystalline lattice period and linear thermal expansion coefficient. One determined lattice constituents of thermal expansion coefficient of hexaborides. On the basis of analysis of temperature curves one made conclusion that processes of splitting of energy levels governing the Schottky contribution into thermal capacity did not practically affect expansion of hexaborides

  15. Determination of the Thermal Expansion Coefficient of Concrete at Early Ages by Using Temperature-stress Testing Machine

    Institute of Scientific and Technical Information of China (English)

    HUO Kaicheng; SHUI Zhonghe; LI Yue

    2006-01-01

    By using the uptodate temperatuer-stress testing machine, the thermal expansion coefficient of concrete at early ages was studied and indicative conclusions were achieved: temperature rising due to hydration heat is not directly correlated with cracking, but the temperature and stress evolution process should be taken into consideration in the same time. Proper chemical admixtures and mineral compositions can improve the mechanical properties of concrete such as thermal expansion coefficient, which is very indicative in practice.

  16. Experimentally determined Henry's law coefficient of phenol, 2-methylphenol and 2-nitrophenol in the temperature range 281-302 K

    OpenAIRE

    Harrison, Mark A. J.

    2002-01-01

    The Henry's Law coefficient is a key physical parameter in the partitioning, and hence environmental fate, of a chemical species between air and water. Despite the acknowledged polluting potential of phenol, 2-methylphenol (o-cresol) and 2- nitrophenol, there is extremely poor agreement in the literature of their Henry's law coefficients and, in particular, no apparent systematic measurement of the variation with temperature. Here, a temperature-controlled column-stripping meth...

  17. Experimentally determined Henry's Law coefficients of phenol, 2-methylphenol and 2-nitrophenol in the temperature range 281-302 K

    OpenAIRE

    Harrison, Mark A. J.; Cape, J. Neil; Heal, Mathew R.

    2002-01-01

    The Henry’s Law coefficient is a key physical parameter in the partitioning, and hence environmental fate, of a chemical species between air and water. Despite the acknowledged polluting potential of phenol, 2-methylphenol (o-cresol) and 2-nitrophenol, there is extremely poor agreement in the literature of their Henry’s law coefficients and, in particular, no apparent systematic measurement of the variation with temperature. Here a temperature controlled column-stripping method was employed t...

  18. Na/Ca selectivity coefficients of Na-montmorillonite at different temperatures

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. The Finnish spent nuclear fuel disposal is based on the KBS-3 concept in crystalline bedrock. The concept aims at long-term isolation and containment of spent fuel in copper canisters surrounded by bentonite buffer which mostly consists of montmorillonite. The cation form affects many essential properties of montmorillonite. In the KBS-3 concept, the maximum temperature limit has been decided as 90 C. The thermal period when spent fuel is supplying heat may last for thousands of years. Thus, for the long-term modelling of the chemical processes in the buffer, the cation-exchange selectivity coefficients have to be known at different temperatures. However, the selectivities for montmorillonite have mostly been studied at room temperature. In this work, the cation-exchange selectivity coefficients and cation-exchange isotherms are determined in batch experiments for montmorillonite at three different temperatures (25, 50 and 75 C). Five different ratios of NaClO4/Ca(ClO4)2 are used in the experimental solutions. After equilibration the solution and montmorillonite are separated and both are analyzed to get the desired exchange parameters. The experiments are modelled with a computational model (PHREEQC), which is capable of taking into account the physicochemical processes that take place in the experiment. The purification is needed to enable accurate experimental results and to exclude any unnecessary complexes and mineral reactions in the montmorillonite. MX-80 bentonite obtained from Wyoming (USA) in powdered form is first purified to Na-montmorillonite form. The purification comprised the removal of large particles, dissolution of carbonates and iron oxides, removal of organic material, changing to the sodium form and removal of the excess salt by washing and finally by dialysis. After the purification the montmorillonite was dried in an oven at 60 C and finally placed in a vacuum freeze dryer. The Na

  19. Determination of Orbiter and Carrier Aerodynamic Coefficients from Load Cell Measurements

    Science.gov (United States)

    Glenn, G. M.

    1976-01-01

    A method of determining orbiter and carrier total aerodynamic coefficients from load cell measurements is required to support the inert and the captive active flights of the ALT program. A set of equations expressing the orbiter and carrier total aerodynamic coefficients in terms of the load cell measurements, the sensed dynamics of the Boeing 747 (carrier) aircraft, and the relative geometry of the orbiter/carrier is derived.

  20. An instrument for the high temperature measurement of the Seebeck coefficient and electrical resistivity

    International Nuclear Information System (INIS)

    A system for the simultaneous measurement of thermoelectric power and resistivity of one and/or two samples over a temperature range of 300–1000 K in a vacuum chamber is designed and implemented. A sample probe is developed to provide its easy mounting and usage. In addition, two samples can be measured at the same time. Measurement accuracy has been enhanced by beadless thermocouples and micro-heaters that are specifically designed in order to minimize the ‘cold-finger effect’ and to eliminate some possible source of contact, design and measurement errors. A broad range of physical types and shapes of samples, such as bulk, bar or disc, can be measured by a software controlled system. A differential steady-state method has been applied for Seebeck coefficient measurement. Resistivity measurement is conducted with the axial technique of the four-point probe method. Platinum wire and a niobium rod are chosen as the standard samples. The total data error for the Seebeck coefficient and resistivity measurements is estimated to be less than 2.6% and 1%, respectively. (paper)

  1. A note on the temperature dependence of Henry's Law coefficients for methanol and ethanol

    Science.gov (United States)

    Warneck, Peter

    Measurements reported in the literature of gas-liquid partition coefficients for methanol and ethanol dissolved in water are compiled and critically evaluated to establish the temperature dependence. The data are linearly correlated in the ln( KH[mol dm -3 atm -1]) versus reciprocal absolute temperature coordinate frame and, when treated by a linear regression analysis, yield: ln( KH)=-(12.46±0.25)+(5312.4±76.0)/ T in the case of methanol (0-80 °C) and ln( KH)=-(15.87±0.82)+(6274.0±241.6)/ T in the case of ethanol (0-60 °C). The measurements at 25 °C average to KH(298.15)=(2.16±0.14)×10 2 mol dm -3 atm -1 ( n=8) and KH(298.15)=(1.94±0.13)×10 2 mol dm -3 atm -1 ( n=8), respectively. Enthalpies of solution derived from the temperature dependence are 44.17±0.63 kJ mol -1 for methanol and 52.16±2.01 kJ mol -1 for ethanol.

  2. Transverse Coefficient of Thermal Expansion Measurements of Carbon Fibers Using ESEM at High Temperatures

    Science.gov (United States)

    Ochoa, O.; Jiang, J.; Putnam, D.; Lo, Z.; Ellis, A.; Effinger, Michael

    2003-01-01

    The transverse coefficient of thermal expansion (CTE) of single IM7, T1000, and P55 carbon fibers are measured at elevated temperatures. The specimens are prepared by press-fitting fiber tows into 0.7mm-diameter cavity in a graphite disk of 5mm in diameter and 3mm high. The specimens are placed on a crucible in an ESEM, and images of the fiber cross section are taken as the fibers are heated up to 800 C. Holding time, heating and cool down cycles are also introduced. The geometrical changes are measured using a graphics tablet. The change in area/perimeter is calculated to determine the strain and transverse CTE for each fiber. In a complimentary computational effort, displacements and stresses are calculated with finite element models.

  3. Experimental measurement of variation of heat transfer coefficient and temperature gradients in 16'' deep fluidised beds

    International Nuclear Information System (INIS)

    The object of the experiments was to choose suitable particulate materials for a fluidised bed cooler, to test a deep fluidised bed for uniformity of heat transfer coefficient, and to explore the temperature distribution in a centrally heated annular fluidised bed. This memorandum records the techniques used and some of the practical aspects involved, together with the performance results obtained, for the assistance of other experimenters who may wish to use fluidised beds as a laboratory technique. Mathematical correlation of the results has not been attempted since some of the properties of the bed material were not known and to determine them was beyond the scope of the work programme. Rather, we have compared our results with those of other experimenters. Graphite tubes, for use in steady state thermal stress experiments, are to be heated by a graphite radiant heater situated in the bore and cooled on the outer surface. The tubes are 2 cm. bore, 8 cm. outside diameter and 48 cm. long. The outside temperature of the tubes is to be between 500 deg. C. and 1500 deg. C. It is estimated that the heat transfer rate required for fracture at the outer surface is 30 watts/cm2. This could readily be achieved by cooling with liquid metals, water or high velocity gas. However, serious problems of either materials compatibility or mechanical complexity make these undesirable. A water-cooled fluidised bed of compatible solids fluidised with nitrogen gas can overcome most of these problems and give heat transfer coefficients close to that required, vis. about 0.1 w/cm C . A coolant bed about 20'' long would be required and an annulus of about 2'' radial width round the specimen was considered to be practicable

  4. Effects of environmental temperature and dietary energy on energy partitioning coefficients of female broiler breeders.

    Science.gov (United States)

    Pishnamazi, A; Renema, R A; Paul, D C; Wenger, I I; Zuidhof, M J

    2015-10-01

    With increasing disparity between broiler breeder target weights and broiler growth potential, maintenance energy requirements have become a larger proportion of total broiler breeder energy intake. Because energy is partitioned to growth and egg production at a lower priority than maintenance, accurate prediction of maintenance energy requirements is important for practical broiler breeder feed allocation decisions. Environmental temperature affects the maintenance energy requirement by changing rate of heat loss to the environment. In the ME system, heat production (energy lost) is part of the maintenance requirement (ME). In the current study, a nonlinear mixed model was derived to predict ME partitioning of broiler breeder hens under varied temperature conditions. At 21 wk of age, 192 Ross 708 hens were individually caged within 6 controlled environmental chambers. From 25 to 41 wk, 4 temperature treatments (15°C, 19°C, 23°C, and 27°C) were randomly assigned to the chambers for 2-week periods. Half of the birds in each chamber were fed a high-energy (HE; 2,912 kcal/kg) diet, and half were fed a low-energy (LE; 2,790 kcal/kg) diet. The nonlinear mixed regression model included a normally distributed random term representing individual hen maintenance, a quadratic response to environmental temperature, and linear ADG and egg mass (EM) coefficients. The model assumed that energy requirements for BW gain and egg production were not influenced by environmental temperature because hens were homeothermic, and the cellular processes for associated biochemical processes occurred within a controlled narrow core body temperature range. Residual feed intake (RFI) and residual ME (RME) were used to estimate efficiency. A quadratic effect of environmental temperature on broiler breeder MEm was predicted ( < 0.0001), with a minimum energy expenditure at 24.3°C. Predicted ME at 21°C was 92.5 kcal/kg; requirements for gain and EM were 2.126 and 1.789 kcal/g, respectively

  5. Preparation and study on performance of submicron nickel powder for multilayer chip positive temperature coefficient resistance

    Institute of Scientific and Technical Information of China (English)

    Chen Yong; Gong Shu-Ping; Fu Qiu-Yun; Zheng Zhi-Ping; Huang Ri-Ming; Su Peng

    2010-01-01

    Base metal nickel is often used as the inner electrode in multilayer chip positive temperature coefficient resistance (PTCR). The fine grain of ceramic powders and base metal nickel are necessary. This paper uses reducing hydrazine to gain submicron nickel powder whose diameter was 200-300 nm through adjusting the consumption of nucleating agent PVP properly. The submicron nickel powder could disperse well and was fit for co-fired of multilayer chip PTCR. It analyes the submicron nickel powder through x-ray Diffraction (XRD) and calculates the diameter of nickel by PDF cards. Using XRD analyses it obtains several conclusions:If the molar ratio of hydrazine hydrate and nickel sulfate is kept to be a constant, when enlarging the molar ratio of NaOH/Ni2+>, the diameter of nickel powder would become smaller. When the temperature in the experiment raises to 70-80 ℃, nickel powder becomes smaller too. And if the molar ratio of NaOH/Ni2+> is 4, when molar ratio of (C2>H5>O)2>/Ni2+> increases, the diameter of nickel would reduce.Results from viewing the powders by optical microscope should be the fact that the electrode made by submicron nickel powder has a better formation and compactness. Furthermore, the sheet resistance testing shows that the electrode made by submicron nickel is smaller than that made by micron nickel.

  6. The Temperature Dependence Coefficients of Amorphous Silicon and Crystalline Photovoltaic Modules Using Malaysian Field Test Investigation

    Directory of Open Access Journals (Sweden)

    Sulaiman Shaari

    2009-01-01

    Full Text Available The temperature dependence coefficients of amorphous silicon and crystalline photovoltaic (PV modules using Malaysian field data have been obtained using linear regression technique. This is achieved by studying three test stand-alone PV-battery systems using 62 Wp a-Si, 225 Wp multi-crystalline and 225 Wp mono-crystalline PV modules. These systems were designed to provide electricity for rural domestic loads at 200 W, 500 W and 530 W respectively. The systems were installed in the field with data monitored using data loggers. Upon analysis, the study found that the normalized power output per operating array temperature for the amorphous silicon modules, multi-crystalline modules and mono-crystalline modules were: +0.037 per°C, +0.0225 per °C and +0.0263 per °C respectively. In addition, at a solar irradiance value of 500 Wm-2, the current, voltage, power and efficiency dependence coefficients on operating array temperatures obtained from linear regression were: +37.0 mA per °C, -31.8 mV per °C, -0.1036 W per °C and -0.0214% per °C, for the a-Si modules, +22.5 mA per °C, -39.4 mV per °C, -0.2525 W per °C, -0.072 % per °C for the multi-crystalline modules and +26.3 mA per °C, -32.6 mV per °C, -0.1742 W per °C, -0.0523 % per °C for the mono-crystalline modules. These findings have a direct impact on all systems design and sizing in similar climate regions. It is thus recommended that the design and sizing of PV systems in the hot and humid climate regions of the globe give due address to these findings.

  7. Temperature coefficient of reactivity of a typical swimming pool type research reactor using low enriched uranium fuel

    International Nuclear Information System (INIS)

    The temperature coefficients of reactivity of a swimming pool type material test research reactor have been calculated using standard computer codes. It is observed that the core reactivity loss due to increase in water temperature and void formation is sensitive to control rod position at criticality. The reactivity decreases more rapidly when the core volume is small. (author)

  8. The effect of filler on the temperature coefficient of the relative permittivity of PTFE/ceramic composites

    Science.gov (United States)

    Rajesh, S.; Murali, K. P.; Jantunen, H.; Ratheesh, R.

    2011-11-01

    High permittivity and low-loss ceramic fillers have been prepared by means of the solid state ceramic route. Ceramic-filled composites were prepared by the Sigma Mixing, Extrusion, Calendering, which was followed by the Hot pressing (SMECH) process. The microwave dielectric properties of the composites were studied using X-band waveguide cavity perturbation technique. The temperature coefficient of the relative permittivity of the composites was investigated in the 0-100 °C temperature range using a hot and cold chamber coupled with an impedance analyzer. The temperature coefficient of the relative permittivity of the composites showed strong dependence on the temperature coefficient of the relative permittivity of the filler material. In the present study, a high-permittivity polymer/ceramic composite, having τεr ∼63 ppm/K, has been realized. This composite is suitable for outdoor wireless applications.

  9. The Seebeck coefficient and the Peltier effect in a polymer electrolyte membrane cell with two hydrogen electrodes

    International Nuclear Information System (INIS)

    Highlights: • The heat change associated with the hydrogen electrode in a polymer electrolyte cell is determined from Seebeck coefficient measurements. • When electric current is passed from left to right in the outer circuit, the anode becomes warmer, while the cathode becomes colder in a thermoelectric cell with hydrogen electrodes. • At Soret equilibrium for water in the fuel cell, most of the entropy of the fuel cell reaction is generated at the anode. -- Abstract: We report that the Seebeck coefficient of a Nafion membrane cell with hydrogen electrodes saturated with water vapour, at 1 bar hydrogen pressure and 340 K, is equal to 670 ± 50 μV/K, meaning that the entropy change of the anode reaction at reversible conditions (67 J/(K mol)) corresponds to a reversible heat release of 22 kJ/mol. The transported entropy of protons across the membrane at Soret equilibrium was estimated from this value to 1 ± 5 J/(K mol). The results were supported by the expected variation in the Seebeck coefficient with the hydrogen pressure. We report also the temperature difference of the electrodes, when passing electric current through the cell, and find that the anode is heated (a Peltier heat effect), giving qualitative support to the result for the Seebeck coefficient. The Seebeck and Peltier effects are related by non-equilibrium thermodynamics theory, and the Peltier heat of the cathode in the fuel cell is calculated for steady state conditions to 6 ± 2 kJ/mol at 340 K. The division of the reversible heat release between the anode and the cathode, can be expected to vary with the current density, as the magnitude of the current density can have a big impact on water transport and water concentration profile

  10. Neutronic study of nuclear reactors. Complete calculation of TRIGA MARKII reactor and calculations of fuel temperature coefficients. (Qualification of WIMS code)

    International Nuclear Information System (INIS)

    The present work shows a group of results, obtained by a neutronic study, concerning the TRIGA MARK II reactor and LIGHT WATER reactors. These studies aim to make cell and diffusion calculations. WIMS D-4 with extended library and DIXY programs are used and tested for those purposes. We also have proceeded to a qualification of WIMS code based on the fuel temperature coefficient calculations. 33 refs.; 23 figs.; 30 tabs. (author)

  11. Experimental high temperature coefficients of compressibility and expansivity of liquid sodium and other related properties

    International Nuclear Information System (INIS)

    The subcooled compressibility of liquid sodium was directly measured up to 200 atm between 900 K and 1867 K, utilizing a new multi-property apparatus which was previously tested with water. The experimental data were correlated by a 6-term equation with a standard deviation of 9.2 percent. The equation can be used to estimate the subcooled compressibilities and densities of liquid sodium up to 2300 K and 500 ata. The thermal expansion of liquid sodium was also measured along the isobars 1 ata, 28.9 ata and 69 ata. Densities within 1 percent of those obtained from the compressibilities were obtained. The above compressibility data were used to calculate the thermal pressure coefficient of saturated liquid sodium. Also, Bhise and Bonilla's correlations for the vapor pressure and the saturated liquid density of sodium were improved by including more data in the analysis. The critical temperature and density were thus reestimated as 2508.7 K and 0.2141 g/cc. Furthermore, a new correlation was developed to determine the heat of vaporization of sodium up to the critical point, which was then used to estimate the internal energy and the entropy of vaporization and the saturated vapor density of sodium up to the critical point

  12. Experimental high temperature coefficients of compressibility and expansivity of liquid sodium and other related properties

    Energy Technology Data Exchange (ETDEWEB)

    Das Gupta, S.

    1977-01-01

    The subcooled compressibility of liquid sodium was directly measured up to 200 atm between 900 K and 1867 K, utilizing a new multi-property apparatus which was previously tested with water. The experimental data were correlated by a 6-term equation with a standard deviation of 9.2 percent. The equation can be used to estimate the subcooled compressibilities and densities of liquid sodium up to 2300 K and 500 ata. The thermal expansion of liquid sodium was also measured along the isobars 1 ata, 28.9 ata and 69 ata. Densities within 1 percent of those obtained from the compressibilities were obtained. The above compressibility data were used to calculate the thermal pressure coefficient of saturated liquid sodium. Also, Bhise and Bonilla's correlations for the vapor pressure and the saturated liquid density of sodium were improved by including more data in the analysis. The critical temperature and density were thus reestimated as 2508.7 K and 0.2141 g/cc. Furthermore, a new correlation was developed to determine the heat of vaporization of sodium up to the critical point, which was then used to estimate the internal energy and the entropy of vaporization and the saturated vapor density of sodium up to the critical point.

  13. Derivation of Regression Coefficients for Sea Surface Temperature Retrieval over East Asia

    Institute of Scientific and Technical Information of China (English)

    Myoung-Hwan AHN; Eun-Ha SOHN; Byong-Jun HWANG; Chu-Yong CHUNG; Xiangqian WU

    2006-01-01

    Among the regression-based algorithms for deriving SST from satellite measurements, regionally optimized algorithms normally perform better than the corresponding global algorithm. In this paper,three algorithms are considered for SST retrieval over the East Asia region (15°-55°N, 105°-170°E),including the multi-channel algorithm (MCSST), the quadratic algorithm (QSST), and the Pathfinder algorithm (PFSST). All algorithms are derived and validated using collocated buoy and Geostationary Meteorological Satellite (GMS-5) observations from 1997 to 2001. An important part of the derivation and validation of the algorithms is the quality control procedure for the buoy SST data and an improved cloud screening method for the satellite brightness temperature measurements. The regionally optimized MCSST algorithm shows an overall improvement over the global algorithm, removing the bias of about -0.13℃ and reducing the root-mean-square difference (rmsd) from 1.36℃ to 1.26℃. The QSST is only slightly better than the MCSST. For both algorithms, a seasonal dependence of the remaining error statistics is still evident. The Pathfinder approach for deriving a season-specific set of coefficients, one for August to October and one for the rest of the year, provides the smallest rmsd overall that is also stable over time.

  14. Temperature dependence of invariant diffusion coefficient and activation energy for Fe-Cr-Ni-Co system

    International Nuclear Information System (INIS)

    Experimental determination of diffusion invariant coefficients in a four-component Fe-Cr-Ni-Co system is conducted for alloys with 16 mas.% of Cr, 13 mas.% of Ni, 2-14 mas.% of Co. Activation energies, corresponding to diffusion invariant coefficients are calculated by the least squares technique. The analysis of concentrational dependences of these coefficients has shown that under a low cobalt content the system can be characterized by the unique activation energy value

  15. Compact, high-Q, zero temperature coefficient, TE011 sapphire-rutile microwave distributed Bragg reflector resonators.

    Science.gov (United States)

    Tobar, M E; Cros, D; Blondy, P; Ivanov, E N

    2001-05-01

    Some novel new resonator designs based on the distributed Bragg reflector are presented. The resonators implement a TE011 resonance in a cylindrical sapphire dielectric, which is confined by the addition of rutile and sapphire dielectric reflectors at the end faces. Finite element calculations are utilized to optimize the dimensions to obtain the highest Q-factors and zero frequency-temperature coefficient for a resonator operating near 0 degree C. We show that a Q-factor of 70,000 and 65,000 can be achieved with and without the condition of zero frequency-temperature coefficients, respectively. PMID:11381707

  16. Effect of temperature and pressure on the overall heat transfer coefficient in VHTR-based SI process heat exchangers

    International Nuclear Information System (INIS)

    In this paper, a sensitivity analysis on the overall heat transfer coefficient has been carried out as a function of operation temperature and pressure. The sulfur-iodine (SI) cycle and Westinghouse sulfur hybrid cycle, combined with a very high temperature gas-cooled reactor (VHTR), are well-known as feasible technologies for hydrogen production. The SI process consists of a Bunsen reactor; H2SO4, SO3, and HIx decomposers; and a HI pre-heater. The overall heat transfer coefficient of the process heat exchanger (PHE) used in the SI process is a very important factor when sizing the PHE

  17. Experimental and Numerical Study on Effects of Airflow and Aqueous Ammonium Temperature on Ammonia Mass Transfer Coefficient

    DEFF Research Database (Denmark)

    Rong, Li; Nielsen, Peter V.; Zhang, Guoqiang

    2010-01-01

    transfer are investigated by using computational fluid dynamics (CFD) modeling and by a mechanism modeling using dissociation constant and Henry's constant models based on the parameters measured in the experiments performed in a wind tunnel. The validated CFD model by experimental data is used to...... constant and Henry's constant models. In addition, the results show that the liquid-air temperature difference has little impact on the simulated mass transfer coefficient by CFD modeling, whereas the mass transfer coefficient increases with higher liquid temperature using the other method under the...

  18. Fabrication and temperature dependence of a GaInP/GaAs/Ge tandem solar cell

    Institute of Scientific and Technical Information of China (English)

    崔敏; 陈诺夫; 杨晓丽; 张汉

    2012-01-01

    GaInP/GaAs/Ge tandem solar cells were fabricated by a MOCVD technique.The photoelectric properties of the solar cells were characterized by a current-voltage test method.The dependence of the solar cell's characteristics on temperature were investigated from 30 to 170 ℃ at intervals of 20 ℃.Test results indicated that with increasing temperature,Jsc of the cell increased slightly with a temperature coefficient of 9.8 (μA/cm2)/℃.Voc reduced sharply with a coefficient of-5.6 mV/℃.FF was reduced with a temperature coefficient of-0.00063/℃.Furthermore,the conversion efficiency decreased linearly with increasing temperature which decreased from 28% at 30 ℃ to 22.1% at 130 ℃.Also,detailed theoretical analyses for temperature characteristics of the solar cell were given.

  19. Effects of magnetic field intensity on carbon diffusion coefficient in pure iron in γ-Fe temperature region

    Science.gov (United States)

    Wu, Yan; Duan, Guosheng; Zhao, Xiang

    2015-03-01

    Effects of magnetic field intensity on carbon diffusion coefficient in pure iron in the γ-Fe temperature region were investigated using carburizing technology. The carbon penetration profiles from the iron surface to interior were measured by field emission electron probe microanalyzer. The carbon diffusion coefficient in pure iron carburized with different magnetic field intensities was calculated according to the Fick's second law. It was found that the magnetic field intensity could obviously affect the carbon diffusion coefficient in pure iron in the γ-Fe temperature region, and the carbon diffusion coefficient decreased obviously with the enhancement of magnetic field intensity, when the magnetic field intensity was higher than 1 T, the carbon diffusion coefficient in field annealed specimen was less than half of that of the nonfield annealed specimen, further enhancing the magnetic field intensity, the carbon diffusion coefficient basically remains unchanged. The stiffening of lattice due to field-induced magnetic ordering was responsible for an increase in activation barrier for jumping carbon atoms. The greater the magnetic field intensity, the stronger the inhibiting effect of magnetic field on carbon diffusion.

  20. Materials for low-temperature fuel cells

    CERN Document Server

    Ladewig, Bradley; Yan, Yushan; Lu, Max

    2014-01-01

    There are a large number of books available on fuel cells; however, the majority are on specific types of fuel cells such as solid oxide fuel cells, proton exchange membrane fuel cells, or on specific technical aspects of fuel cells, e.g., the system or stack engineering. Thus, there is a need for a book focused on materials requirements in fuel cells. Key Materials in Low-Temperature Fuel Cells is a concise source of the most important and key materials and catalysts in low-temperature fuel cells. A related book will cover key materials in high-temperature fuel cells. The two books form part

  1. Low temperature diffusion coefficients in the Fe-Ni and FeNiP systems: Application to meteorite cooling rates

    Science.gov (United States)

    Dean, D. C.; Goldstein, J. I.

    1984-01-01

    The interdiffusion coefficient of FeNi in fcc taenite (gamma) of Fe-Ni and Fe-Ni-0.2 P alloys was measured as a function of temperature between 600 and 900 C. This temperature range is directly applicable to the nucleation and growth of the Widmanstatten pattern in iron meteorites and metal regions of stony and stony-iron meteorites. Diffusion couples were made from FeNi or FeNiP alloys which ensured that the couples were in the taenite phase at the diffusion temperature. The presence or absence of grain boundary diffusion was determined by measuring the Ni profile normal to the existing grain boundaries with the AEM. Ignoring any variation of interdiffusion coefficient with composition, the measured data was plotted versus the reciprocal of the diffusion temperature. The FeNi data generally follow the extrapolated Goldstein, et al. (1965) data from high temperatures. The FeNiP data indicates that small additions of P (0.2 wt%) cause a 3 to 10 fold increase in the FeNi interdifussion coefficient increasing with decreasing temperature. This increase is about the same as that predicted by Narayan and Goldstein (1983) at the Widmanstatten growth temperature.

  2. First integrals and analytical solutions of the nonlinear fin problem with temperature-dependent thermal conductivity and heat transfer coefficient

    Indian Academy of Sciences (India)

    EMRULLAH YA¸SAR; YAKUP YILDIRIM; ILKER BURAK GIRESUNLU

    2016-08-01

    Fin materials can be observed in a variety of engineering applications. They are used to ease the dissipation of heat from a heated wall to the surrounding environment. In this work, we consider a nonlinear fin problem with temperature-dependent thermal conductivity and heat transfer coefficient. The equation(s) under study are highly nonlinear. Both the thermal conductivity and the heat transfer coefficient are given as arbitrary functions of temperature. Firstly, we consider the Lie group analysis for different cases of thermal conductivity and the heat transfer coefficients. These classifications are obtained from the Lie group analysis. Then, the first integrals of the nonlinear straight fin problem are constructed by three methods, namely, Noether’s classical method, partial Noether approach and Ibragimov’s nonlocal conservation method. Some exact analytical solutions are also constructed. The obtained result is also compared with the result obtained by other methods.

  3. Convergence of Cell Based Finite Volume Discretizations for Problems of Control in the Conduction Coefficients

    DEFF Research Database (Denmark)

    Evgrafov, Anton; Gregersen, Misha Marie; Sørensen, Mads Peter

    2011-01-01

    design, in particular shape and topology optimization, and are most often solved numerically utilizing a finite element approach. Within the FV framework for control in the coefficients problems the main difficulty we face is the need to analyze the convergence of fluxes defined on the faces of cells...

  4. A unified derivation of the various definitions of lattice cell diffusion coefficient

    International Nuclear Information System (INIS)

    The various definitions of lattice cell diffusion coefficients are discussed within the context of a one-dimensional slab lattice in one energy group. It is shown how each definition, although originally derived in its own particular way, can be derived from a single approach. This makes clear the differences between, and the advantages of, the various definitions. (author)

  5. Determination of diffusion coefficients of carbon dioxide in water between 268 and 473 K in a high-pressure capillary optical cell with in situ Raman spectroscopic measurements

    Science.gov (United States)

    Lu, Wanjun; Guo, Huirong; Chou, I.-Ming; Burruss, R.C.; Li, Lanlan

    2013-01-01

    Accurate values of diffusion coefficients for carbon dioxide in water and brine at reservoir conditions are essential to our understanding of transport behavior of carbon dioxide in subsurface pore space. However, the experimental data are limited to conditions at low temperatures and pressures. In this study, diffusive transfer of carbon dioxide in water at pressures up to 45 MPa and temperatures from 268 to 473 K was observed within an optical capillary cell via time-dependent Raman spectroscopy. Diffusion coefficients were estimated by the least-squares method for the measured variations in carbon dioxide concentration in the cell at various sample positions and time. At the constant pressure of 20 MPa, the measured diffusion coefficients of carbon dioxide in water increase with increasing temperature from 268 to 473 K. The relationship between diffusion coefficient of carbon dioxide in water [D(CO2) in m2/s] and temperature (T in K) was derived with Speedy–Angell power-law approach as: D(CO2)=D0[T/Ts-1]m where D0 = 13.942 × 10−9 m2/s, Ts = 227.0 K, and m = 1.7094. At constant temperature, diffusion coefficients of carbon dioxide in water decrease with pressure increase. However, this pressure effect is rather small (within a few percent).

  6. Determination of Scattering and Absorption Coefficients for Plasma-Sprayed Yttria-Stabilized Zirconia Thermal Barrier Coatings at Elevated Temperatures

    Science.gov (United States)

    Eldridge, Jeffrey I.; Spuckler, Charles M.; Markham, James R.

    2009-01-01

    The temperature dependence of the scattering and absorption coefficients for a set of freestanding plasma-sprayed 8 wt% yttria-stabilized zirconia (8YSZ) thermal barrier coatings (TBCs) was determined at temperatures up to 1360 C in a wavelength range from 1.2 micrometers up to the 8YSZ absorption edge. The scattering and absorption coefficients were determined by fitting the directional-hemispherical reflectance and transmittance values calculated by a four-flux Kubelka Munk method to the experimentally measured hemispherical-directional reflectance and transmittance values obtained for five 8YSZ thicknesses. The scattering coefficient exhibited a continuous decrease with increasing wavelength and showed no significant temperature dependence. The scattering is primarily attributed to the relatively temperature-insensitive refractive index mismatch between the 8YSZ and its internal voids. The absorption coefficient was very low (less than 1 per centimeter) at wavelengths between 2 micrometers and the absorption edge and showed a definite temperature dependence that consisted of a shift of the absorption edge to shorter wavelengths and an increase in the weak absorption below the absorption edge with increasing temperature. The shift in the absorption edge with temperature is attributed to strongly temperature-dependent multiphonon absorption. While TBC hemispherical transmittance beyond the absorption edge can be predicted by a simple exponential decrease with thickness, below the absorption edge, typical TBC thicknesses are well below the thickness range where a simple exponential decrease in hemispherical transmittance with TBC thickness is expected. [Correction added after online publication August 11, 2009: "edge to a shorter wavelengths" has been updated as edge to shorter wavelengths."

  7. Materials for high-temperature fuel cells

    CERN Document Server

    Jiang, San Ping; Lu, Max

    2013-01-01

    There are a large number of books available on fuel cells; however, the majority are on specific types of fuel cells such as solid oxide fuel cells, proton exchange membrane fuel cells, or on specific technical aspects of fuel cells, e.g., the system or stack engineering. Thus, there is a need for a book focused on materials requirements in fuel cells. Key Materials in High-Temperature Fuel Cells is a concise source of the most important and key materials and catalysts in high-temperature fuel cells with emphasis on the most important solid oxide fuel cells. A related book will cover key mater

  8. Temperature anomaly of the coefficient of ultrasonic absorption by electrons of hybridized states of cobalt impurities in mercury selenide

    Science.gov (United States)

    Zhevstovskikh, I. V.; Okulov, V. I.; Gudkov, V. V.; Mayakin, V. Yu.; Sarychev, M. N.; Andriichuk, M. D.; Paranchich, L. D.

    2015-05-01

    The effects of the interaction of ultrasound with donor d electrons of cobalt impurity atoms at low concentrations in mercury selenide crystals have been investigated. The temperature dependences of the electronic contribution to the absorption coefficient at a frequency of 53 MHz in crystals with cobalt concentrations from 1018 to 1020 cm-3 and in the undoped crystal have been observed experimentally. It has been found that crystals with impurities are characterized by an anomalous nonmonotonic temperature dependence of the absorption coefficient of the slow transverse wave in a narrow temperature range near 10 K. A smooth monotonic temperature dependence has been observed for longitudinal and fast transverse waves. Based on the developed theoretical interpretation, it has been established that the anomaly in the temperature dependence of the absorption coefficient of a slow transverse wave is associated with the hybridization of impurity d states in the conduction band of the crystal. A comparison of the theoretical and experimental dependences has made it possible to determine the parameters characterizing the hybridized electronic states.

  9. Influence of Chemical Composition on Phase Transformation Temperature and Thermal Expansion Coefficient of Hot Work Die Steel

    Institute of Scientific and Technical Information of China (English)

    XIE Hao-jie; WU Xiao-chun; MIN Yong-an

    2008-01-01

    On the basis of the uniform design method,six kinds of martensitie hot work die steels were designed.The phase transformation temperatures including Ac1,Ac3,and M,were measured by DIL805A quenching dilatometer.The influences of the main elements on phase transformation temperatures were analyzed by quadratic stepwise regression analysis,and three corresponding equations were obtained.These equations,in which the interactions of the elements were considered,showed more effectiveness than the traditional ones.In addition,the thermal expansion coefficients of these steels in annealed state and quenched state were also obtained during the tests.The influences of chemical composition and temperature on the thermal expansion coefficient were analyzed;the equations obtained Were verified by using several kinds of steels.The predicted values were in accordance with the results of the experiments.

  10. Temperature Coefficient of Sound Velocity of Perovskite-Enstatite and Lateral Thermal Heterogeneity in Earth's Lower Mantle

    Institute of Scientific and Technical Information of China (English)

    GONG Zi-Zheng; XIE Hong-Sen; JING Fu-Qian; LIU Yong-Gang; GUO Jie; XU Jian

    2000-01-01

    Using the differences of sound velocity and temperature on the Hugoniot and isoentropic state, the temperature coefficients of sound velocity of perovskite-enstatite under high pressure were obtained. For compressional, shear and bulk wave velocities, their temperature coefficients decrease from 0.386, 0.251, 0.255m/(s.K) at 40GPa to 0.197, 0.131, 0. 162m/(s.K) at 140GPa, respectively. Extrapolating these to zero pressure results in ( K/ T)0 =-0.0279 GPa. K-1, which is consistent very well with the value got by hydrostatic pressure experiment. On the basis of our data, we conclude that the compressional wave velocity anomaly of 0.1-0.2% in the deep lower mantle and 2% in the D" region would imply lateral thermal heterogeneity with amplitude of 53-106 K and 1066 K in these regions, respectively.

  11. Determination of barrier height temperature coefficient by Norde's method in ideal Co/n-GaAs Schottky contacts

    OpenAIRE

    TURUT, Abdulmecit

    2012-01-01

    We have formed the ideal Co/n-GaAs Schottky barrier diodes (SBDs) by magnetron DC sputtering. The experimental current-voltage data of the Co/n-GaAs SBD are almost independent of the sample temperature and quite well obey the thermionic emission model from 100 K to 320 K. We have showed that the temperature coefficient of the barrier height can be determined using Norde's method instead of the temperature-dependent capacitance-voltage measurements or the flat-band barrier height ...

  12. Temperature dependence of hydrogenated amorphous silicon solar cell performances

    Science.gov (United States)

    Riesen, Y.; Stuckelberger, M.; Haug, F.-J.; Ballif, C.; Wyrsch, N.

    2016-01-01

    Thin-film hydrogenated amorphous silicon solar (a-Si:H) cells are known to have better temperature coefficients than crystalline silicon cells. To investigate whether a-Si:H cells that are optimized for standard conditions (STC) also have the highest energy yield, we measured the temperature and irradiance dependence of the maximum power output (Pmpp), the fill factor (FF), the short-circuit current density (Jsc), and the open-circuit voltage (Voc) for four series of cells fabricated with different deposition conditions. The parameters varied during plasma-enhanced chemical vapor deposition (PE-CVD) were the power and frequency of the PE-CVD generator, the hydrogen-to-silane dilution during deposition of the intrinsic absorber layer (i-layer), and the thicknesses of the a-Si:H i-layer and p-type hydrogenated amorphous silicon carbide layer. The results show that the temperature coefficient of the Voc generally varies linearly with the Voc value. The Jsc increases linearly with temperature mainly due to temperature-induced bandgap reduction and reduced recombination. The FF temperature dependence is not linear and reaches a maximum at temperatures between 15 °C and 80 °C. Numerical simulations show that this behavior is due to a more positive space-charge induced by the photogenerated holes in the p-layer and to a recombination decrease with temperature. Due to the FF(T) behavior, the Pmpp (T) curves also have a maximum, but at a lower temperature. Moreover, for most series, the cells with the highest power output at STC also have the best energy yield. However, the Pmpp (T) curves of two cells with different i-layer thicknesses cross each other in the operating cell temperature range, indicating that the cell with the highest power output could, for instance, have a lower energy yield than the other cell. A simple energy-yield simulation for the light-soaked and annealed states shows that for Neuchâtel (Switzerland) the best cell at STC also has the best energy

  13. Dynamic Model of High Temperature PEM Fuel Cell Stack Temperature

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen

    2007-01-01

    The present work involves the development of a model for predicting the dynamic temperature of a high temperature PEM (HTPEM) fuel cell stack. The model is developed to test different thermal control strategies before implementing them in the actual system. The test system consists of a prototype...... stack at a high stoichiometric air flow. This is possible because of the PBI fuel cell membranes used, and the very low pressure drop in the stack. The model consists of a discrete thermal model dividing the stack into three parts: inlet, middle and end and predicting the temperatures in these three...... parts, where also the temperatures are measured. The heat balance of the system involves a fuel cell model to describe the heat added by the fuel cells when a current is drawn. Furthermore the model also predicts the temperatures, when heating the stack with external heating elements for start-up, heat...

  14. Investigation on low room-temperature resistivity Cr/(Ba0.85Pb0.15)TiO3 positive temperature coefficient composites

    DEFF Research Database (Denmark)

    He, Zeming; Ma, J.; Qu, Yuanfang;

    2009-01-01

    Low room-temperature resistivity positive temperature coefficient (PTC) Cr/(Ba0.85Pb0.15)TiO3 composites were produced via a reducing sintering and a subsequent oxidation treatment. The effects of metallic content and processing conditions on materials resistivity–temperature properties were...... discussed. Using these special processes, the prepared composite with 20 wt% Cr possessed low room-temperature resistivity (2.96 Ω cm at 25 °C) and exhibited PTC effect (resistivity jump of 10), which is considered as a promising candidate for over-current protector when working at low voltage. The grain...

  15. Shear piezoelectric coefficients of PZT, LiNbO3 and PMN-PT at cryogenic temperatures

    Science.gov (United States)

    Bukhari, Syed; Islam, Md; Haziot, Ariel; Beamish, John

    2014-12-01

    Piezoelectric transducers are used to detect stress and to generate nanometer scale displacements but their piezoelectric coefficients decrease with temperature, limiting their performance in cryogenic applications. We have developed a capacitive technique and directly measured the temperature dependence of the shear coefficient d15 for ceramic lead zirconium titanate (PZT), 41° X-cut lithium niobate (LiNbO3) and single crystal lead magnesium niobium-lead titanate (PMN-PT). In PZT, d15 decreases nearly linearly with temperature, dropping by factor of about 4 by 1.3 K. LiNbO3 has the smallest room temperature d15, but its value decreased by only 6% at the lowest temperatures. PMN-PT had the largest value of d15 at room temperature (2.9 × 10-9 m/V, about 45 times larger than for LiNbO3) but it decreased rapidly below 75 K; at 1.3 K, d15 was only about 8% of its room temperature value.

  16. On the Effect of Counterface Materials on Interface Temperature and Friction Coefficient of GFRE Composite Under Dry Sliding Contact

    Directory of Open Access Journals (Sweden)

    N. S.M. El-Tayeb

    2005-01-01

    Full Text Available Nowadays, there is an increase interest in polymeric composite materials for high-performance in many industrial applications. In other words, the tribo-studies on polymeric materials are growing fast to enhance the polymeric products such as bearings, seals, ring and bushes. The current work presents an attempt to study the correlation between the type of counterface material and frictional heating at the interface surfaces for different, normal loads (23N, 49N and 72N, sliding velocities (0.18, 1.3 and 5.2 m sˉ1 and interval time (0-720 sec. Sliding friction experiments are performed on a pin-on-ring (POR tribometer under dry contact condition. Interface temperature and friction force were measured simultaneously during sliding of glass fiber reinforced epoxy (GFRE composite against three different counter face materials, hardened steel (HS, cast iron (CI and Aluminum alloy (Al. Experimental results showed that the type of counterface material greatly influences both interface temperature and friction coefficient. Higher temperature and friction coefficient were evident when sliding took place against HS surface, compared to sliding against CI and Al under same condition. When sliding took place against HS, the friction coefficient of GFRE composite was about an order of magnitude higher than sliding the GFRE composite against the other counter face materials. Based on the optical microscope graphs, the friction and induced temperature results of GFRE composite are analyzed and discussed.

  17. Design and fabrication of a length-extensional mode rectangular X-cut quartz resonator with zero temperature coefficient.

    Science.gov (United States)

    Yokoyama, Yukio; Kawashima, Hirofumi; Kanie, Hisashi

    2006-05-01

    Rectangular X-cut quartz crystal resonators with cut angles theta > 5.0 degrees and aspect ratios Rzy (= width 2z0/length 2y0) from 0.3 to 0.5 are investigated. The resonators oscillate mode is a length-extensional mode. A semiempirical frequency equation was derived from the stress expressed in terms of the trigonometric and the hyperbolic transcendental functions with constants estimated by the regression curve fit to the stress simulated by the finite-element method (FEM). Contours on which a point satisfies a zero first order temperature coefficient condition are shown in a cut angle theta and Rzy diagram. We proved that a fabricated resonator with Rzy = 0.400 and theta = 16.0 degrees, whose design parameter is located in the area of the contour, had a zero temperature coefficient. PMID:16764439

  18. Turbulent Transfer Coefficients and Calculation of Air Temperature inside Tall Grass Canopies in Land Atmosphere Schemes for Environmental Modeling.

    Science.gov (United States)

    Mihailovic, D. T.; Alapaty, K.; Lalic, B.; Arsenic, I.; Rajkovic, B.; Malinovic, S.

    2004-10-01

    A method for estimating profiles of turbulent transfer coefficients inside a vegetation canopy and their use in calculating the air temperature inside tall grass canopies in land surface schemes for environmental modeling is presented. The proposed method, based on K theory, is assessed using data measured in a maize canopy. The air temperature inside the canopy is determined diagnostically by a method based on detailed consideration of 1) calculations of turbulent fluxes, 2) the shape of the wind and turbulent transfer coefficient profiles, and 3) calculation of the aerodynamic resistances inside tall grass canopies. An expression for calculating the turbulent transfer coefficient inside sparse tall grass canopies is also suggested, including modification of the corresponding equation for the wind profile inside the canopy. The proposed calculations of K-theory parameters are tested using the Land Air Parameterization Scheme (LAPS). Model outputs of air temperature inside the canopy for 8 17 July 2002 are compared with micrometeorological measurements inside a sunflower field at the Rimski Sancevi experimental site (Serbia). To demonstrate how changes in the specification of canopy density affect the simulation of air temperature inside tall grass canopies and, thus, alter the growth of PBL height, numerical experiments are performed with LAPS coupled with a one-dimensional PBL model over a sunflower field. To examine how the turbulent transfer coefficient inside tall grass canopies over a large domain represents the influence of the underlying surface on the air layer above, sensitivity tests are performed using a coupled system consisting of the NCEP Nonhydrostatic Mesoscale Model and LAPS.

  19. Measurement of the fuel temperature and the fuel-to-coolant heat transfer coefficient of Super Phenix 1 fuel elements

    International Nuclear Information System (INIS)

    A new measurement method for measuring the mean fuel temperature as well as the fuel-to-coolant heat transfer coefficient of fast breeder reactor subassemblies (SA) is reported. The method is based on the individual heat balance of fuel SA's after fast reactor shut-downs and uses only the plants normal SA outlet temperature and neutron power signals. The method was used successfully at the french breeder prototype Super Phenix 1. The mean SA fuel temperature as well as the heat transfer coefficient of all SPX SA's have been determined at power levels between 15 and 90% of nominal power and increasing fuel burn-up from 3 to 83 EFPD (Equivalent of Full Power-Days). The measurements also provided fuel and whole SA time constants. The estimated accuracy of measured fuel parameters is in the order of 10%. Fuel temperatures and SA outlet temperature transients were also calculated with the SPX1 systems code DYN2 for exactly the same fuel and reactor operating parameters as in the experiments. Measured fuel temperatures were higher than calculated ones in all cases. The difference between measured and calculated core mean values increases from 50 K at low power to 180 K at 90% n.p. This is about the double of the experimental error margins. Measured SA heat transfer coefficients are by nearly 20% lower than corresponding heat transfer parameters used in the calculations. Discrepancies found between measured and calculated results also indicate that either the transient heat transfer in the gap between fuel and cladding (gap conductance) might not be exactly reproduced in the computer code or that the gap in the fresh fuel was larger than assumed in the calculations. (orig.)

  20. Monte Carlo perturbation analysis on isothermal temperature reactivity coefficient of light-water moderated and reflected critical assembly

    International Nuclear Information System (INIS)

    Experiments have been carried out on the isothermal temperature reactivity coefficient (ITRC) for the light-water moderated core at the Kyoto University Critical Assembly. The temperature effect on reactivity is analyzed by the Seoul National University Monte Carlo (MC) code, McCARD, which well reproduce experimental data. The contributions of the each isotope by the density changes of the core and reflector regions and the microscopic cross section changes to the ITRCs are quantified by sensitivity analyses based on the MC adjoint-weighted perturbation methods. (author)

  1. Feasibility of a simple laboratory approach for determining temperature influence on SPMD-air partition coefficients of selected compounds

    Science.gov (United States)

    Cicenaite, A.; Huckins, J.N.; Alvarez, D.A.; Cranor, W.L.; Gale, R.W.; Kauneliene, V.; Bergqvist, P.-A.

    2007-01-01

    Semipermeable membrane devices (SPMDs) are a widely used passive sampling methodology for both waterborne and airborne hydrophobic organic contaminants. The exchange kinetics and partition coefficients of an analyte in a SPMD are mediated by its physicochemical properties and certain environmental conditions. Controlled laboratory experiments are used for determining the SPMD-air (Ksa's) partition coefficients and the exchange kinetics of organic vapors. This study focused on determining a simple approach for measuring equilibrium Ksa's for naphthalene (Naph), o-chlorophenol (o-CPh) and p-dichlorobenzene (p-DCB) over a wide range of temperatures. SPMDs were exposed to test chemical vapors in small, gas-tight chambers at four different temperatures (-16, -4, 22 and 40 ??C). The exposure times ranged from 6 h to 28 d depending on test temperature. Ksa's or non-equilibrium concentrations in SPMDs were determined for all compounds, temperatures and exposure periods with the exception of Naph, which could not be quantified in SPMDs until 4 weeks at the -16 ??C temperature. To perform this study the assumption of constant and saturated atmospheric concentrations in test chambers was made. It could influence the results, which suggest that flow through experimental system and performance reference compounds should be used for SPMD calibration. ?? 2006 Elsevier Ltd. All rights reserved.

  2. Feasibility of a simple laboratory approach for determining temperature influence on SPMD–air partition coefficients of selected compounds

    Science.gov (United States)

    Cicenaite, Aurelija; Huckins, James N.; Alvarez, David A.; Cranor, Walter L.; Gale, Robert W.; Kauneliene, Violeta; Bergqvist, Per-Anders

    2007-01-01

    Semipermeable membrane devices (SPMDs) are a widely used passive sampling methodology for both waterborne and airborne hydrophobic organic contaminants. The exchange kinetics and partition coefficients of an analyte in a SPMD are mediated by its physicochemical properties and certain environmental conditions. Controlled laboratory experiments are used for determining the SPMD–air (Ksa's) partition coefficients and the exchange kinetics of organic vapors. This study focused on determining a simple approach for measuring equilibrium Ksa's for naphthalene (Naph), o-chlorophenol (o-CPh) and p-dichlorobenzene (p-DCB) over a wide range of temperatures. SPMDs were exposed to test chemical vapors in small, gas-tight chambers at four different temperatures (−16, −4, 22 and 40 °C). The exposure times ranged from 6 h to 28 d depending on test temperature. Ksa's or non-equilibrium concentrations in SPMDs were determined for all compounds, temperatures and exposure periods with the exception of Naph, which could not be quantified in SPMDs until 4 weeks at the −16 °C temperature. To perform this study the assumption of constant and saturated atmospheric concentrations in test chambers was made. It could influence the results, which suggest that flow through experimental system and performance reference compounds should be used for SPMD calibration.

  3. Fabrication of a simple apparatus for the Seebeck coefficient measurement in the temperature range of 300-620 K

    CERN Document Server

    Singh, Saurabh

    2015-01-01

    A simple apparatus for the measurement of Seebeck coefficient ({\\alpha}) in the temperature range 300-620 K has been fabricated. Our design is appropriate for the characterization of samples with different geometries like disk and rod shaped. The sample holder assembly of the apparatus has been designed in such a way that, single heater used for sample heating purpose is enough to provide a self maintain temperature gradient (1-10 K) across the sample. The value of $\\alpha$ is obtained without explicit measurement of temperature gradient. The whole apparatus is fabricated from the materials, which are commonly available, so that any part can be replaced in case of any damage. Commercially available standard Nickel (Ni) metal sample has been used as a reference material for calibration of the instrument. The experimentally observed value of {\\alpha} by our apparatus gives the similar temperature dependent behavior as reported in the literature.

  4. A novel (ex situ) method to quantify oxygen diffusion coefficient of polymer fuel cells backing and catalyst layers

    Science.gov (United States)

    Baricci, Andrea; Casalegno, Andrea

    2016-09-01

    Limiting current density of oxygen reduction reaction in polymer electrolyte fuel cells is determined by several mass transport resistances that lower the concentration of oxygen on the catalyst active site. Among them, diffusion across porous media plays a significant role. Despite the extensive experimental activity documented in PEMFC literature, only few efforts have been dedicated to the measurement of the effective transport properties in porous layers. In the present work, a methodology for ex situ measurement of the effective diffusion coefficient and Knudsen radius of porous layers for polymer electrolyte fuel cells (gas diffusion layer, micro porous layer and catalyst layer) is described and applied to high temperature polymer fuel cells State of Art materials. Regression of the measured quantities by means of a quasi 2D physical model is performed to quantify the Knudsen effect, which is reported to account, respectively, for 30% and 50% of the mass transport resistance in micro porous layer and catalyst layer. On the other side, the model reveals that pressure gradient consequent to permeation in porous layers of high temperature polymer fuel cells has a negligible effect on oxygen concentration in relevant operating conditions.

  5. Effect of Two Temperatures on Reflection Coefficient in Micropolar Thermoelastic with and without Energy Dissipation Media

    Directory of Open Access Journals (Sweden)

    Rajneesh Kumar

    2014-01-01

    Full Text Available The reflection of plane waves at the free surface of thermally conducting micropolar elastic medium with two temperatures is studied. The theory of thermoelasticity with and without energy dissipation is used to investigate the problem. The expressions for amplitudes ratios of reflected waves at different angles of incident wave are obtained. Dissipation of energy and two-temperature effects on these amplitude ratios with angle of incidence are depicted graphically. Some special and particular cases are also deduced.

  6. Water Diffusion Coefficients of Selected Legumes Grown in Turkey As Affected by Temperature and Variety

    OpenAIRE

    SEYHAN-GÜRTAŞ, Ferda; AK, M. Mehmet; Evranuz, E. Özgül

    2001-01-01

    The kinetics of water absorption by chickpeas (Koçbaşı, Kuşbaşı), lentils (green Pul) and beans (Battal, Dermason, Horoz, Şeker) grown in Turkey were studied by a gravimetric method during soaking at 15, 25 and 40ºC to determine moisture diffusivity of these selected legumes. The water diffusion coefficients of the legumes were in the range 9.71x10-11 - 5.98x10-10 m2/s for the chickpeas, 3.53x10-10 - 1.33x10-9 m2/s for the lentils and 4.35x10-11 - 3.79x10-9 m2/s for the beans. An Arrhenius-t...

  7. Remarks on the contribution of electron-phonon scattering to low-temperature transport coefficients in metals

    International Nuclear Information System (INIS)

    For very low temperature, the technical difficulty of calculating the electron-phonon contribution to transport coefficients in metals can be substantially reduced. The collision operator reduces to the product of an integral operator on the energy dependence, with a differential (or multiplicative) operator on the angular dependence of the distribution function for electrical (or thermal) conduction. This simple asymptotic limit of the collision operator as T → O is proven, and from it a number of results are derived. These results include statements about the distribution function and the transport coefficients, but the most useful ones are the simplified formulae that occur for collision matrix elements and for α2F(ω) distributions appropriate to transport

  8. Mid-infrared response of reduced graphene oxide and its high-temperature coefficient of resistance

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Haifeng, E-mail: hfliang2004@gmail.com [Key Laboratory of Optical Measurement and Thin Film of Shaanxi Province, Xi’an Technological University, Xi’an 710032 (China)

    2014-10-15

    Much effort has been made to study the formation mechanisms of photocurrents in graphene and reduced graphene oxide films under visible and near-infrared light irradiation. A built-in field and photo-thermal electrons have been applied to explain the experiments. However, much less attention has been paid to clarifying the mid-infrared response of reduced graphene oxide films at room temperature. Thus, mid-infrared photoresponse and annealing temperature-dependent resistance experiments were carried out on reduced graphene oxide films. A maximum photocurrent of 75 μA was observed at room temperature, which was dominated by the bolometer effect, where the resistance of the films decreased as the temperature increased after they had absorbed light. The electrons localized in the defect states and the residual oxygen groups were thermally excited into the conduction band, forming a photocurrent. In addition, a temperature increase of 2 °C for the films after light irradiation for 2 minutes was observed using absorption power calculations. This work details a way to use reduced graphene oxide films that contain appropriate defects and residual oxygen groups as bolometer-sensitive materials in the mid-infrared range.

  9. Mid-infrared response of reduced graphene oxide and its high-temperature coefficient of resistance

    Directory of Open Access Journals (Sweden)

    Haifeng Liang

    2014-10-01

    Full Text Available Much effort has been made to study the formation mechanisms of photocurrents in graphene and reduced graphene oxide films under visible and near-infrared light irradiation. A built-in field and photo-thermal electrons have been applied to explain the experiments. However, much less attention has been paid to clarifying the mid-infrared response of reduced graphene oxide films at room temperature. Thus, mid-infrared photoresponse and annealing temperature-dependent resistance experiments were carried out on reduced graphene oxide films. A maximum photocurrent of 75 μA was observed at room temperature, which was dominated by the bolometer effect, where the resistance of the films decreased as the temperature increased after they had absorbed light. The electrons localized in the defect states and the residual oxygen groups were thermally excited into the conduction band, forming a photocurrent. In addition, a temperature increase of 2 °C for the films after light irradiation for 2 minutes was observed using absorption power calculations. This work details a way to use reduced graphene oxide films that contain appropriate defects and residual oxygen groups as bolometer-sensitive materials in the mid-infrared range.

  10. Temperature dependence of friction coefficient and wear rate of hard coatings

    International Nuclear Information System (INIS)

    This paper resumes results of our study of the temperature dependent parameters of TiN, CoCr, CoCrN and MoS2 coatings. All investigated coatings were sputtered by means of a system of unbalanced magnetrons with pulsed d.c. supply. The most important deposition parameters ( e.g. total and partial pressures of Ar+N2 mixture, sample bias) were registered. The coatings thickness, determined by means of Calotest method, was 2 - 3 μm. The adhesion was measured with a scratch tester, for coating structure and internal stress evaluation the XRD and for coatings hardness the Hanemann microhardness were used. The temperature dependence of tribological parameters was determined by means of a high temperature tribometer (Authors)

  11. Determination of absorption coefficients of glasses at high tempera-tures, by measuring the thermal emission

    NARCIS (Netherlands)

    Loenen, E.; Van der Tempel, L.

    1996-01-01

    An experimental setup built in 1995 measures the spectral absorptioncoefficient of glass as a function of temperature and wavelength bythe emissive method. The setup was improved, as well as the softwarefor processing the measurement data. The measurement results of quartzwere validated by compariso

  12. Temperature dependence of the electrical conductivity and Seebeck coefficient of new poly(ester-syloxane)urethane elastomers in thin films

    Energy Technology Data Exchange (ETDEWEB)

    Rusu, M.; Rusu, G.G.; Bucescu, M.; Rusu, G.I. [A.I. Cuza Univ., Iassy (Romania). Fac. of Phys.; Stanciu, A.; Bulacovschi, V. [`P. Poni` Institute of Macromolecular Chemistry, Aleea Grigore Ghica Voda, 41 A, Iassy, R-6600 (Romania)

    1998-08-04

    The temperature dependences of the electrical conductivity and the Seebeck coefficient for some new poly(ester-syloxane)urethane elastomers are studied. The measurements have been performed using thin films deposited from solution. It is found that the investigated polymers have semiconducting properties. Values of some semiconducting parameters of these films (activation energy of electrical conduction, charge carrier concentration, ratio of carrier mobilities) have been calculated. The correlations between some of these parameters and the molecular structure of the respective polymers are discussed. (orig.) 41 refs.

  13. On the Calculation of the Critical Temperature from the Second Virial Coefficient

    Czech Academy of Sciences Publication Activity Database

    Nezbeda, Ivo; Smith, W. R.

    2004-01-01

    Roč. 216, č. 1 (2004), s. 183-186. ISSN 0378-3812 R&D Projects: GA AV ČR IAA4072303 Grant ostatní: NATO PST .CLG.(XX) 978178/6343 Institutional research plan: CEZ:AV0Z4072921 Keywords : critical temperature * virial expansion * perturbation expansion Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.356, year: 2004

  14. Heat transfer analysis of a fin with temperature-dependent thermal conductivity and heat transfer coefficient

    Directory of Open Access Journals (Sweden)

    Hadi Mirgolbabaee

    2015-02-01

    Results are presented for the dimensionless temperature distribution and fin efficiency for different values of the problem parameters which for the purpose of comparison, obtained equation were calculated with mentioned methods. It was found the proposed solution is very accurate, efficient, and convenient for the discussed problem, furthermore convergence problems for solving nonlinear equations by using AGM appear small so the results demonstrate that the AGM could be applied through other methods in nonlinear problems with high nonlinearity.

  15. Fabrication of Ta–Si–N/Ag nanocomposite thin films with near-zero temperature coefficient of resistance

    International Nuclear Information System (INIS)

    Highlights: • Composite thin films with Ag nano-grains uniformly distributed in amorphous Ta–Si–N matrix are obtained. • The temperature coefficient of resistance and the resistivity can be well adjusted by changing Si component. • The balance between quantum tunneling effect and phonon scattering effect results in near-zero TCR. • The near-zero TCR can be maintained at an extremely low temperature from 105 K to 225 K. - Abstract: Ta–Si–N/Ag nanocomposite thin films were prepared by reactive magnetron co-sputtering of Ta, Si and Ag targets in the plasma of N2 and Ar. It was found that Ag nano-grains were uniformly distributed in the amorphous matrix due to the incorporation of Si. The sizes of Ag grains and the separation between them could be well controlled by changing the Si component, which can be adopted to improve the electronic properties of the composite resistive films. A near-zero temperature coefficient of resistance (TCR) of +39.7 ppm/K was obtained in the thin films with a Si component of 5.88 at.% as a result of the balance of quantum tunneling effect and phonon scattering effect. This is consolidated by the changes in the measured carrier density and Hall mobility at different temperatures. Particularly, the near-zero TCR could be maintained at an extremely low temperature from 105 K to 225 K. The results are of great significance for the exploitation of high-performance resistive thin films

  16. Temperature-dependent solubilities and mean ionic activity coefficients of alkali halides in water from molecular dynamics simulations.

    Science.gov (United States)

    Mester, Zoltan; Panagiotopoulos, Athanassios Z

    2015-07-28

    The mean ionic activity coefficients of aqueous KCl, NaF, NaI, and NaCl solutions of varying concentrations have been obtained from molecular dynamics simulations following a recently developed methodology based on gradual insertions of salt molecules [Z. Mester and A. Z. Panagiotopoulos, J. Chem. Phys. 142, 044507 (2015)]. The non-polarizable ion models of Weerasinghe and Smith [J. Chem. Phys. 119, 11342 (2003)], Gee et al. [J. Chem. Theory Comput. 7, 1369 (2011)], Reiser et al. [J. Chem. Phys. 140, 044504 (2014)], and Joung and Cheatham [J. Phys. Chem. B 112, 9020 (2008)] were used along with the extended simple point charge (SPC/E) water model [Berendsen et al., J. Phys. Chem. 91, 6269 (1987)] in the simulations. In addition to the chemical potentials in solution used to obtain the activity coefficients, we also calculated the chemical potentials of salt crystals and used them to obtain the solubility of these alkali halide models in SPC/E water. The models of Weerasinghe and Smith [J. Chem. Phys. 119, 11342 (2003)] and Gee et al. [J. Chem. Theory Comput. 7, 1369 (2011)] provide excellent predictions of the mean ionic activity coefficients at 298.15 K and 1 bar, but significantly underpredict or overpredict the solubilities. The other two models generally predicted the mean ionic activity coefficients only qualitatively. With the exception of NaF for which the solubility is significantly overpredicted, the model of Joung and Cheatham predicts salt solubilities that are approximately 40%-60% of the experimental values. The models of Reiser et al. [J. Chem. Phys. 140, 044504 (2014)] make good predictions for the NaCl and NaI solubilities, but significantly underpredict the solubilities for KCl and NaF. We also tested the transferability of the models to temperatures much higher than were used to parametrize them by performing simulations for NaCl at 373.15 K and 1 bar, and at 473.15 K and 15.5 bar. All models overpredict the drop in the values of mean ionic

  17. Temperature-related changes in respiration and Q10 coefficient of Guava

    Directory of Open Access Journals (Sweden)

    Bron Ilana Urbano

    2005-01-01

    Full Text Available Guava (Psidium guajava L. is a tropical fruit that presents fast post-harvest ripening; therefore it is a very perishable product. Inappropriate storage temperature and retail practices can accelerate fruit quality loss. The objective of this study was to evaluate the respiratory activity (RA, the ethylene production (EP and Q10 of guava fruit at different storage temperatures. 'Paluma' guava fruits were harvested at maturity stage 1 (dark-green skin and stored at either 1, 11, 21, 31 or 41ºC; RA and EP were determined after 12, 36, 84 and 156 h of storage. RA and EP rates at 1 and 11ºC were the lowest - 0.16 and 0.43 mmol CO2 kg-1 h-1 and 0.003 and 0.019 µmol C2H4 kg-1 h-1, respectively. When guavas were stored at 21ºC, a gradual increase occurred in RA and EP, reaching 2.24 mmol CO2 kg-1 h-1 and 0.20 µmol C2H4 kg-1 h-1, after 156 h of storage. The highest RA and EP were recorded for guavas stored at 31ºC. In spite of high RA, guavas stored at 41ºC presented EP similar to guavas stored at 11ºC, an indicator of heat-stress injury. Considering the 1-11ºC range, the mean Q10 value was around 3.0; the Q10 value almost duplicated at 11-21ºC range (5.9. At 21-31ºC and 31-41ºC, Q10 was 1.5 and 0.8, respectively. Knowing Q10, respiratory variation and ripening behavior in response to different temperatures, fruit storage and retail conditions can be optimized to reduce quality losses.

  18. Modeling of thermal expansion coefficient of perovskite oxide for solid oxide fuel cell cathode

    Science.gov (United States)

    Heydari, F.; Maghsoudipour, A.; Alizadeh, M.; Khakpour, Z.; Javaheri, M.

    2015-09-01

    Artificial intelligence models have the capacity to eliminate the need for expensive experimental investigation in various areas of manufacturing processes, including the material science. This study investigates the applicability of adaptive neuro-fuzzy inference system (ANFIS) approach for modeling the performance parameters of thermal expansion coefficient (TEC) of perovskite oxide for solid oxide fuel cell cathode. Oxides (Ln = La, Nd, Sm and M = Fe, Ni, Mn) have been prepared and characterized to study the influence of the different cations on TEC. Experimental results have shown TEC decreases favorably with substitution of Nd3+ and Mn3+ ions in the lattice. Structural parameters of compounds have been determined by X-ray diffraction, and field emission scanning electron microscopy has been used for the morphological study. Comparison results indicated that the ANFIS technique could be employed successfully in modeling thermal expansion coefficient of perovskite oxide for solid oxide fuel cell cathode, and considerable savings in terms of cost and time could be obtained by using ANFIS technique.

  19. High-Temperature Solar Cell Development

    Science.gov (United States)

    Landis, Geoffrey A.; Raffaelle, Ryne P.; Merritt, Danielle

    2004-01-01

    The vast majority of satellites and near-earth probes developed to date have relied upon photovoltaic power generation. If future missions to probe environments close to the sun will be able to use photovoltaic power, solar cells that can function at high temperatures, under high light intensity, and high radiation conditions must be developed. For example, the equilibrium temperature of a Mercury surface station will be about 450 C, and the temperature of solar arrays on the proposed "Solar Probe" mission will extend to temperatures as high as 2000 C (although it is likely that the craft will operate on stored power rather than solar energy during the closest approach to the sun). Advanced thermal design principles, such as replacing some of the solar array area with reflectors, off-pointing, and designing the cells to reflect rather than absorb light out of the band of peak response, can reduce these operating temperature somewhat. Nevertheless, it is desirable to develop approaches to high-temperature solar cell design that can operate under temperature extremes far greater than today's cells. Solar cells made from wide bandgap (WBG) compound semiconductors are an obvious choice for such an application. In order to aid in the experimental development of such solar cells, we have initiated a program studying the theoretical and experimental photovoltaic performance of wide bandgap materials. In particular, we have been investigating the use of GaP, SiC, and GaN materials for space solar cells. We will present theoretical results on the limitations on current cell technologies and the photovoltaic performance of these wide-bandgap solar cells in a variety of space conditions. We will also give an overview of some of NASA's cell developmental efforts in this area and discuss possible future mission applications.

  20. Effect of variable heat transfer coefficient on tissue temperature next to a large vessel during radiofrequency tumor ablation

    Directory of Open Access Journals (Sweden)

    Pinheiro Cleber

    2008-07-01

    Full Text Available Abstract Background One of the current shortcomings of radiofrequency (RF tumor ablation is its limited performance in regions close to large blood vessels, resulting in high recurrence rates at these locations. Computer models have been used to determine tissue temperatures during tumor ablation procedures. To simulate large vessels, either constant wall temperature or constant convective heat transfer coefficient (h have been assumed at the vessel surface to simulate convection. However, the actual distribution of the temperature on the vessel wall is non-uniform and time-varying, and this feature makes the convective coefficient variable. Methods This paper presents a realistic time-varying model in which h is a function of the temperature distribution at the vessel wall. The finite-element method (FEM was employed in order to model RF hepatic ablation. Two geometrical configurations were investigated. The RF electrode was placed at distances of 1 and 5 mm from a large vessel (10 mm diameter. Results When the ablation procedure takes longer than 1–2 min, the attained coagulation zone obtained with both time-varying h and constant h does not differ significantly. However, for short duration ablation (5–10 s and when the electrode is 1 mm away from the vessel, the use of constant h can lead to errors as high as 20% in the estimation of the coagulation zone. Conclusion For tumor ablation procedures typically lasting at least 5 min, this study shows that modeling the heat sink effect of large vessels by applying constant h as a boundary condition will yield precise results while reducing computational complexity. However, for other thermal therapies with shorter treatment using a time-varying h may be necessary.

  1. Measurement of solid state diffusion coefficients by a temperature-programmed method

    International Nuclear Information System (INIS)

    This paper presents a method for determining diffusivities in solids where the diffusing species desorbs or reacts at the external surfaces, and where the diffusivity does not vary appreciably with concentration. The method involves measuring the flux of the diffusive species out of the solid under the influence of a temperature program. A general model is developed, based on non-isothermal Fickian diffusion, which is applicable to solid particles with slab or spherical geometry. The solution is presented both as an analytical expression and as correlation charts of experimentally observable quantities. These charts are contour diagrams of the temperature of peak diffusion rate with ln(E/R) and ln(D0/h2) as the axes, where E and D0 are the activation energy and pre-exponential terms of the diffusivity expression D=D0exp(-E/RT), R is the gas constant, and h the size of the particles. This paper deals exclusively with the case of oxygen diffusion in the vanadium oxide system. In this case, vanadium oxide was reduced in a reactive ammonia stream at conditions in which the surface reaction was fast compared to the diffusive transport process. Using this method the diffusion parameters were found to be D0=1.9x10-5cm2s-1and E=101 kJ/mol. the method was checked by varying the crystallite size of the vanadium oxide sample in the range 2h=0.14 endash 0.29 μm. copyright 1997 Materials Research Society

  2. Transport of temperature-velocity covariance in gas-solid flow and its relation to the axial dispersion coefficient

    Science.gov (United States)

    Subramaniam, Shankar; Sun, Bo

    2015-11-01

    The presence of solid particles in a steady laminar flow generates velocity fluctuations with respect to the mean fluid velocity that are termed pseudo-turbulence. The level of these pseudo-turbulent velocity fluctuations has been characterized in statistically homogeneous fixed particle assemblies and freely evolving suspensions using particle-resolved direct numerical simulation (PR-DNS) by Mehrabadi et al. (JFM, 2015), and it is found to be a significant contribution to the total kinetic energy associated with the flow. The correlation of these velocity fluctuations with temperature (or a passive scalar) generates a flux term that appears in the transport equation for the average fluid temperature (or average scalar concentration). The magnitude of this transport of temperature-velocity covariance is quantified using PR-DNS of thermally fully developed flow past a statistically homogeneous fixed assembly of particles, and the budget of the average fluid temperature equation is presented. The relation of this transport term to the axial dispersion coefficient (Brenner, Phil. Trans. Roy. Soc. A, 1980) is established. The simulation results are then interpreted in the context of our understanding of axial dispersion in gas-solid flow. NSF CBET 1336941.

  3. High temperature coefficient of resistance of low-temperature-grown VO2 films on TiO2-buffered SiO2/Si (100) substrates

    International Nuclear Information System (INIS)

    The introduction of a TiO2 buffer layer significantly improved the temperature coefficient of resistance (TCR), a measure of the sharpness of the metal–insulator transition, for films of VO2 grown on SiO2/Si (100) substrates at growth temperatures below 670 K. X-ray diffraction and Raman scattering measurements revealed that polycrystalline VO2 films were formed on the TiO2-buffered substrates at low temperatures below 600 K, whereas amorphous films were formed at these temperatures on SiO2/Si (100) substrates without a TiO2 buffer layer. Electron microscopy studies confirmed that the TiO2 buffer layer enhanced the grain growth of VO2 films at low growth temperatures. The VO2 films grown at 600 K on TiO2-buffered substrates showed a large TCR of more than 80%/K as a result of the improved crystallinity and grain size of the VO2 films. Our results provide an effective approach toward the integration of VO2-based devices onto Si platforms at process temperatures below 670 K

  4. Intermediate Temperature Solid Oxide Fuel Cell Development

    Energy Technology Data Exchange (ETDEWEB)

    S. Elangovan; Scott Barnett; Sossina Haile

    2008-06-30

    Solid oxide fuel cells (SOFCs) are high efficiency energy conversion devices. Present materials set, using yttria stabilized zirconia (YSZ) electrolyte, limit the cell operating temperatures to 800 C or higher. It has become increasingly evident however that lowering the operating temperature would provide a more expeditious route to commercialization. The advantages of intermediate temperature (600 to 800 C) operation are related to both economic and materials issues. Lower operating temperature allows the use of low cost materials for the balance of plant and limits degradation arising from materials interactions. When the SOFC operating temperature is in the range of 600 to 700 C, it is also possible to partially reform hydrocarbon fuels within the stack providing additional system cost savings by reducing the air preheat heat-exchanger and blower size. The promise of Sr and Mg doped lanthanum gallate (LSGM) electrolyte materials, based on their high ionic conductivity and oxygen transference number at the intermediate temperature is well recognized. The focus of the present project was two-fold: (a) Identify a cell fabrication technique to achieve the benefits of lanthanum gallate material, and (b) Investigate alternative cathode materials that demonstrate low cathode polarization losses at the intermediate temperature. A porous matrix supported, thin film cell configuration was fabricated. The electrode material precursor was infiltrated into the porous matrix and the counter electrode was screen printed. Both anode and cathode infiltration produced high performance cells. Comparison of the two approaches showed that an infiltrated cathode cells may have advantages in high fuel utilization operations. Two new cathode materials were evaluated. Northwestern University investigated LSGM-ceria composite cathode while Caltech evaluated Ba-Sr-Co-Fe (BSCF) based pervoskite cathode. Both cathode materials showed lower polarization losses at temperatures as low as 600

  5. Vapor pressures, osmotic and activity coefficients for (LiBr + acetonitrile) between the temperatures (298.15 and 343.15) K

    International Nuclear Information System (INIS)

    Precise vapor pressure data for pure acetonitrile and (LiBr + acetonitrile) are given for temperatures ranging from T=(298.15 to 343.15) K. The molality range is from m=(0.0579 to 0.8298) mol · kg-1. The osmotic coefficients are calculated by taking into account the second virial coefficient of acetonitrile. The parameters of the extended Pitzer ion interaction model of Archer and the mole fraction-based thermodynamic model of Clegg-Pitzer are evaluated. These models accurately reproduce the available osmotic coefficients. The parameters of the extended Pitzer ion interaction model of Archer are used to calculate the mean molal activity coefficients

  6. Test on temperature coefficient of standard capacitors%标准电容器的温度系数试验

    Institute of Scientific and Technical Information of China (English)

    戴冬雪; 王维; 金攀; 何小兵

    2015-01-01

    Standard capacitor is a kind of material metrology instrument, the change of environmental temperature is the main factor of capacitance variation. According to JJG183-1992 Verification Regulation of Standard Capacitors, we per-formed the test on temperature coefficient of standard capacitors. The test verifies the temperature characteristic of the capacitors which are made of different dielectric materials.%作为实物计量器具的标准电容器,环境温度的变化是引起其容量变化的主要因素。依据JJG183-1992《标准电容器检定规程》,对标准电容器进行了温度系数试验,验证了不同介质材料制造的标准电容器的温度特性,为标准电容器的检定校准工作提供了试验依据。

  7. Determination of equilibrium electron temperature and times using an electron swarm model with BOLSIG+ calculated collision frequencies and rate coefficients

    International Nuclear Information System (INIS)

    Electromagnetic pulse (EMP) events produce low-energy conduction electrons from Compton electron or photoelectron ionizations with air. It is important to understand how conduction electrons interact with air in order to accurately predict EMP evolution and propagation. An electron swarm model can be used to monitor the time evolution of conduction electrons in an environment characterized by electric field and pressure. Here a swarm model is developed that is based on the coupled ordinary differential equations (ODEs) described by Higgins et al. (1973), hereinafter HLO. The ODEs characterize the swarm electric field, electron temperature, electron number density, and drift velocity. Important swarm parameters, the momentum transfer collision frequency, energy transfer collision frequency, and ionization rate, are calculated and compared to the previously reported fitted functions given in HLO. These swarm parameters are found using BOLSIG+, a two term Boltzmann solver developed by Hagelaar and Pitchford (2005), which utilizes updated cross sections from the LXcat website created by Pancheshnyi et al. (2012). We validate the swarm model by comparing to experimental effective ionization coefficient data in Dutton (1975) and drift velocity data in Ruiz-Vargas et al. (2010). In addition, we report on electron equilibrium temperatures and times for a uniform electric field of 1 StatV/cm for atmospheric heights from 0 to 40 km. We show that the equilibrium temperature and time are sensitive to the modifications in the collision frequencies and ionization rate based on the updated electron interaction cross sections

  8. Determination of equilibrium electron temperature and times using an electron swarm model with BOLSIG+ calculated collision frequencies and rate coefficients

    Science.gov (United States)

    Pusateri, Elise N.; Morris, Heidi E.; Nelson, Eric M.; Ji, Wei

    2015-08-01

    Electromagnetic pulse (EMP) events produce low-energy conduction electrons from Compton electron or photoelectron ionizations with air. It is important to understand how conduction electrons interact with air in order to accurately predict EMP evolution and propagation. An electron swarm model can be used to monitor the time evolution of conduction electrons in an environment characterized by electric field and pressure. Here a swarm model is developed that is based on the coupled ordinary differential equations (ODEs) described by Higgins et al. (1973), hereinafter HLO. The ODEs characterize the swarm electric field, electron temperature, electron number density, and drift velocity. Important swarm parameters, the momentum transfer collision frequency, energy transfer collision frequency, and ionization rate, are calculated and compared to the previously reported fitted functions given in HLO. These swarm parameters are found using BOLSIG+, a two term Boltzmann solver developed by Hagelaar and Pitchford (2005), which utilizes updated cross sections from the LXcat website created by Pancheshnyi et al. (2012). We validate the swarm model by comparing to experimental effective ionization coefficient data in Dutton (1975) and drift velocity data in Ruiz-Vargas et al. (2010). In addition, we report on electron equilibrium temperatures and times for a uniform electric field of 1 StatV/cm for atmospheric heights from 0 to 40 km. It is shown that the equilibrium temperature and time are sensitive to the modifications in the collision frequencies and ionization rate based on the updated electron interaction cross sections.

  9. Series integration of the diaphragm cell transport equation when the diffusion coefficient is a function of concentration

    Science.gov (United States)

    Cain, Judith B.; Baird, James K.

    1992-01-01

    An integral of the form, t = B0 + BL ln(Delta-c) + B1(Delta-c) + B2(Delta-c)-squared + ..., where t is the time and Delta-c is the concentration difference across the frit, is derived in the case of the diaphragm cell transport equation where the interdiffusion coefficient is a function of concentration. The coefficient, B0, is a constant of the integration, while the coefficients, BL, B1, B2,..., depend in general upon the constant, the compartment volumes, and the interdiffusion coefficient and various of its concentration derivatives evaluated at the mean concentration for the cell. Explicit formulas for BL, B1, B2,... are given.

  10. Development of a non-intrusive method for the determination of the moderator temperature coefficient of reactivity (MTC)

    Energy Technology Data Exchange (ETDEWEB)

    Demaziere, C

    2000-07-01

    The Moderator Temperature Coefficient of reactivity (MTC) plays an important role in the feedback mechanism and thus in the inherent stability of Pressurised Water Reactors (PWRs). Due to the inaccuracy of the traditional at-power MTC measurement techniques, many power utilities nowadays only measure the zero-power MTC since its determination is relatively straightforward and accurate. For the at-power MTC determination during the remaining fuel cycle, core calculations are assumed to be reliable enough. Nevertheless, these calculations were never benchmarked and most importantly, the use of high burnup fuel might induce a slightly positive MTC at Beginning Of Cycle (BOC) due to the high initial boron concentration. Even if in such a case the Doppler effect would still insure a negative reactivity feedback, monitoring the MTC throughout the cycle could become crucial. In this respect, not only the sign of the MTC is of importance, but also its magnitude. Consequently, developing a method that would permit monitoring the MTC during the fuel cycle is of great interest. One of the main disadvantages of the traditional at-power MTC measurement techniques is that the reactor has to be perturbed in order to induce a change of the moderator temperature. The modification of other parameters that can only be estimated by core calculation represents also a severe drawback of these methods, both for their precision and their reliability. A measurement performed at Ringhals-4 by using the so-called boron dilution method revealed that the uncertainty associated to the MTC estimation could even be much larger than previously expected due to the calculated reactivity corrections. These corrections are very sensitive to the input parameters chosen for the core simulation, and slight mis-estimations of these have large reactivity effects. It is known that if the reactivity noise and the moderator temperature noise could be measured, the MTC could be determined without disturbing

  11. Development of a non-intrusive method for the determination of the moderator temperature coefficient of reactivity (MTC)

    International Nuclear Information System (INIS)

    The Moderator Temperature Coefficient of reactivity (MTC) plays an important role in the feedback mechanism and thus in the inherent stability of Pressurised Water Reactors (PWRs). Due to the inaccuracy of the traditional at-power MTC measurement techniques, many power utilities nowadays only measure the zero-power MTC since its determination is relatively straightforward and accurate. For the at-power MTC determination during the remaining fuel cycle, core calculations are assumed to be reliable enough. Nevertheless, these calculations were never benchmarked and most importantly, the use of high burnup fuel might induce a slightly positive MTC at Beginning Of Cycle (BOC) due to the high initial boron concentration. Even if in such a case the Doppler effect would still insure a negative reactivity feedback, monitoring the MTC throughout the cycle could become crucial. In this respect, not only the sign of the MTC is of importance, but also its magnitude. Consequently, developing a method that would permit monitoring the MTC during the fuel cycle is of great interest. One of the main disadvantages of the traditional at-power MTC measurement techniques is that the reactor has to be perturbed in order to induce a change of the moderator temperature. The modification of other parameters that can only be estimated by core calculation represents also a severe drawback of these methods, both for their precision and their reliability. A measurement performed at Ringhals-4 by using the so-called boron dilution method revealed that the uncertainty associated to the MTC estimation could even be much larger than previously expected due to the calculated reactivity corrections. These corrections are very sensitive to the input parameters chosen for the core simulation, and slight mis-estimations of these have large reactivity effects. It is known that if the reactivity noise and the moderator temperature noise could be measured, the MTC could be determined without disturbing

  12. FLOW VELOCITY AND SURFACE TEMPERATURE EFFECTS ON CONVECTIVE HEAT TRANSFER COEFFICIENT FROM URBAN CANOPY SURFACES BY NUMERICAL SIMULATION

    Directory of Open Access Journals (Sweden)

    Sivaraja Subramania Pillai

    2013-06-01

    Full Text Available This study investigates the effect of flow velocity and building surface temperature effects on Convective Heat Transfer Coefficient (CHTC from urban building surfaces by numerical simulation. The thermal effects produced by geometrical and physical properties of urban areas generate a relatively differential heating and uncomfortable environment compared to rural regions called as Urban Heat Island (UHI phenomena. The urban thermal comfort is directly related to the CHTC from the urban canopy surfaces. This CHTC from urban canopy surfaces expected to depend upon the wind velocity flowing over the urban canopy surfaces, urban canopy configurations, building surface temperature etc. But the most influential parameter on CHTC has not been clarified yet. Urban canopy type experiments in thermally stratified wind tunnel have normally been used to study the heat transfer issues. But, it is not an easy task in wind tunnel experiments to evaluate local CHTC, which vary on individual canyon surfaces such as building roof, walls and ground. Numerical simulation validated by wind tunnel experiments can be an alternative for the prediction of CHTC from building surfaces in an urban area. In our study, wind tunnel experiments were conducted to validate the low-Reynolds-number k-ε model which was used for the evaluation of CHTC from surfaces. The calculated CFD results showed good agreement with experimental results. After this validation, the effects of flow velocity and building surface temperature effects on CHTC from urban building surfaces were investigated. It has been found that the change in velocity remarkably affects the CHTC from urban canopy surfaces and change in surface temperature has almost no effect over the CHTC from urban canopy surfaces.

  13. Silicon Heterojunction Solar Cells: Temperature Impact on Passivation and Performance

    Energy Technology Data Exchange (ETDEWEB)

    Seif, J.; Krishnamani, G.; Demaurex, B.; Martin de Nicholas, S.; Holm, N.; Ballif, C.; De Wolf, S.

    2015-03-23

    Photovoltaic devices deployed in the field can reach operation temperatures (T) as high as 90 °C [1]. Hence, their temperature coefficients (TC1) are of great practical importance as they determine their energy yield. In this study we concentrate on T-related lifetime variations of amorphous/crystalline interfaces and study their influence on the TCs of the individual solar cell parameters. We find that both the open-circuit voltage (Voc) and fill factor (FF) are influenced by these lifetime variations. However, this is only a minor effect compared to the dominant increase of the intrinsic carrier density and the related increase in dark saturation current density. Additionally, in this paper we will show that the TCVoc does not depend solely on the initial value of the Voc [2, 3], but that the structure of the device has to be considered as well.

  14. High temperature polymer electrolyte membrane fuel cell

    Institute of Scientific and Technical Information of China (English)

    K.Scott; M. Mamlouk

    2006-01-01

    One of the major issues limiting the introduction of polymer electrolyte membrane fuel cells (PEMFCs) is the low temperature of operation which makes platinum-based anode catalysts susceptible to poisoning by the trace amount of CO, inevitably present in reformed fuel. In order to alleviate the problem of CO poisoning and improve the power density of the cell, operating at temperature above 100 ℃ is preferred. Nafion(R) -type perfluorosulfonated polymers have been typically used for PEMFC. However, the conductivity of Nafion(R) -type polymers is not high enough to be used for fuel cell operations at higher temperature ( > 90 ℃) and atmospheric pressure because they dehydrate under these condition.An additional problem which faces the introduction of PEMFC technology is that of supplying or storing hydrogen for cell operation,especially for vehicular applications. Consequently the use of alternative fuels such as methanol and ethanol is of interest, especially if this can be used directly in the fuel cell, without reformation to hydrogen. A limitation of the direct use of alcohol is the lower activity of oxidation in comparison to hydrogen, which means that power densities are considerably lower. Hence to improve activity and power output higher temperatures of operation are preferable. To achieve this goal, requires a new polymer electrolyte membrane which exhibits stability and high conductivity in the absence of liquid water.Experimental data on a polybenzimidazole based PEMFC were presented. A simple steady-state isothermal model of the fuel cell is also used to aid in fuel cell performance optimisation. The governing equations involve the coupling of kinetic, ohmic and mass transport. This paper also considers the advances made in the performance of direct methanol and solid polymer electrolyte fuel cells and considers their limitations in relation to the source and type of fuels to be used.

  15. A study of the influence of temperature dependent thermal conductivity on static power coefficient of PFBR oxide core using a variational one dimensional finite element methodology

    International Nuclear Information System (INIS)

    A study has been carried out to examine the influence of temperature dependent thermal conductivity on the static power coefficient of reactivity for Prototype Fast Breeder Reactor (PFBR) oxide core. Change in core material density, core boundary movement, core 1 to core 2 fuel movement, Doppler coefficient and spacer pad expansion effects due to power rise, have been considered for calculating the power coefficient. For temperature rise calculations for the case of temperature dependent thermal conductivity of fuel, one dimensional finite element method based on variational approach has been applied. It is observed that for the case of temperature dependent thermal conductivity, average temperature of the fuel pin in the middle portion is higher but it is lower in the bottom and upper part of the pin than the case of temperature independent thermal conductivity. Because of this opposing effect, over all static power coefficient is influenced, marginally though it is higher for the case when thermal conductivity is temperature dependent. The paper provides the details of the results. (author). 2 refs., 2 tabs., 1 fig

  16. FINITE ELEMENT NUMERICAL SIMULATION OF TEMPERATURE FIELD IN METAL PATTERN CASTING SYSTEM AND "REVERSE METHOD" OF DEFINING THE THERMAL PHYSICAL COEFFICIENT

    Institute of Scientific and Technical Information of China (English)

    L. Chen; P.L. Wang; P.N. Song; J.Y. Zhang

    2007-01-01

    With the technology support of virtual reality and ANSYS software, an example on the simulation of temperature distribution of casting system during the solidification process was provided, which took the latent heat of phase change, the conditions for convection, and the interface heat transfer coefficient into consideration. The result of ANSYS was found to agree well with the test data. This research offers an unorthodox way or "reverse method" of defining the relevant thermal physical coefficient.

  17. The nature of single-ion activity coefficients calculated from potentiometric measurements on cells with liquid junctions

    International Nuclear Information System (INIS)

    Highlights: → Problem of ionic activity coefficients, determined by potentiometry, is reconsidered. → They are found to be functions of mean activity coefficients and transport numbers of ions. → The finding is verified by calculations and comparing the results with reported data. → Calculations are performed for systems with single electrolytes and binary mixtures. - Abstract: Potentiometric measurements on cells with liquid junctions are sometimes used for calculations of single-ion activity coefficients in electrolyte solutions, the incidence of this being increased recently. As surmised by Guggenheim in the 1930s, such coefficients (of ions i), γi, are actually complicated functions of mean ionic activity coefficients, γ±, and transport numbers of ions, ti. In the present paper specific functions γi(γ±, ti) are derived for a number of cell types with an arbitrary mixture of strong electrolytes in a one-component solvent in the liquid-junction system. The cell types include cells with (i) identical electrodes, (ii) dissimilar electrodes reversible to the same ions, (iii) dissimilar electrodes reversible to ions of opposite charge signs, (iv) dissimilar electrodes reversible to different ions of the same charge sign, and (v) identical reference electrodes and an ion-selective membrane permeable to ions of only one type. Pairs of functions for oppositely charged ions are found to be consistent with the mean ionic activity coefficients as would be expected for pairs of the proper γi quantities by definition of γ±. The functions are tested numerically on some of the reported γi datasets that are the more tractable. A generally good agreement is found with data reported for cells with single electrolytes HCl and KCl in solutions, and with binary mixtures in the liquid-junction systems of KCl from the reference solutions and NaCl and HCl from the test solutions. It is found that values of γi(γ±, ti) functions, in general, do depend on the

  18. The Fragment Constant Method for Predicting Octanol-Air Partition Coefficients of Persistent Organic Pollutants at Different Temperatures

    Science.gov (United States)

    Li, Xuehua; Chen, Jingwen; Zhang, Li; Qiao, Xianliang; Huang, Liping

    2006-09-01

    The octanol-air partition coefficient (KOA) is a key physicochemical parameter for describing the partition of organic pollutants between air and environmental organic phases. Experimental determination of KOA is costly and time consuming, and sometimes restricted by lack of sufficiently pure chemicals. There is a need to develop a simple but accurate method to estimate KOA. In the present study, a fragment constant model based on five fragment constants and one structural correction factor, was developed for predicting logKOA at temperatures ranging from 10 to 40°C. The model was validated as successful by statistical analysis and external experimental logKOA data. Compared to other quantitative structure-property relationship methods, the present model has the advantage that it is much easier to implement. As aromatic compounds that contain C, H, O, Cl, and Br atoms, were included in the training set used to develop the model, the current fragment model applies to a wide range of chlorinated and brominated aromatic pollutants, such as chlorobenzenes, polychlorinated naphthalenes, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and dibenzofurans, polycyclic aromatic hydrocarbons, and polybrominated diphenyl ethers, all of which are typical persistent organic pollutants. Further study is necessary to expand the utility of the method to all halogenated aliphatic and aromatic compounds.

  19. Thermodynamic properties and transport coefficients of high-temperature CO2 thermal plasmas mixed with C2F4

    Science.gov (United States)

    Yang, Aijun; Liu, Yang; Sun, Bowen; Wang, Xiaohua; Cressault, Yann; Zhong, Linlin; Rong, Mingzhe; Wu, Yi; Niu, Chunping

    2015-12-01

    This paper is devoted to the calculation of fundamental properties of CO2 mixed with C2F4. The species composition and thermodynamic properties (mass density, entropy, enthalpy and specific heat at constant pressure) are based on Gibbs free energy minimization. The transport properties (electrical conductivity, viscosity and thermal conductivity) are calculated by the well-known Chapman-Enskog method. The Lennard-Jones like phenomenological potential and some recently updated transport cross sections are adopted to obtain collision integrals. The calculation is developed in the temperature range between 300 and 30 000 K, for a pressure between 1 to 16 bar and for several C2F4 proportions. Transport coefficients for CO2 are also compared with previous published values, and the reasons for discrepancies are analyzed. The results obtained for CO2-C2F4 mixtures provide reliable reference data for the simulation of switching arcs in CO2 circuit breakers with the ablation of PTFE.

  20. Zero temperature coefficient of frequency crystal cuts in monoclinic NdCa4O(BO3)3 piezoelectric crystals

    International Nuclear Information System (INIS)

    The temperature coefficient of frequency (TCF) was investigated in monoclinic NdCa4O(BO3)3 (NdCOB) piezoelectric crystals over the temperature range of -140 C to 200 C. A zero TCF characteristic was achieved for the (ZXw) 15 crystal cut, with turnover point at 20 C. The electromechanical coupling k26 and piezoelectric coefficient d26, in shear vibration mode, were determined to be 25% and 13.5 pC/N, respectively. The zero TCF crystal cut, large coupling factor and high piezoelectric coefficient, together with a high mechanical quality factor (Q > 10,000), demonstrate NdCOB crystals promising candidates for bulk acoustic wave resonators over a wide temperature range. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Simulation of temperature rise in Li-ion cells at very high currents

    Science.gov (United States)

    Mao, Jing; Tiedemann, William; Newman, John

    2014-12-01

    The Dualfoil model is used to simulate the electrochemical behavior and temperature rise for MCMB/LiCoO2 Li-ion cells under a small constant-resistance load, approaching a short-circuit condition. Radial mass transport of lithium from the center of the pore to the pore wall has been added to the model to describe better current limitations at very high discharge currents. Electrolyte and solid-surface-concentration profiles of lithium ions across the cell at various times are developed and analyzed to explain the lithium-ion transport limitations. Sensitivity tests are conducted by changing solution and solid-state diffusion coefficients, and the heat-transfer coefficient. Because diffusion coefficients increase at high temperature, calculated discharge curves can show currents dropping initially but then rising to a second peak, with most of the available capacity being consumed in the second peak. Conditions which lead to such a second peak are explored.

  2. Novel Low Temperature Solid State Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chonglin; Nash, Patrick; Liu, Jian; Collins, Gregory

    2009-12-15

    We have successfully fabricated (PrBa)Co{sub 2}O{sub 5+{delta}} and (LaBa)Co{sub 2}O{sub 5+{deleta}} epitaxial thin film on various single crystal substrates. Physical and electrochemical properties characterizations were carried out. Highly conductive oxygen-deficient double perovskite LnBaCo2O5+? thin films were grown on single crystal (001) SrTiO{sub 3} (STO), (001) MgO, (001) LaAlO{sub 3} and (110) NdGaO{sub 3} substrate by pulsed laser deposition. Microstructure studies from synchrotron X-ray diffraction and Transmission electron microscopy. High temperature transport properties was carried in different atmosphere (O{sub 2},Air, N{sub 2}) up to ~900K. Resistance response of (LaBa)Co{sub 2}O{sub 5+{delta}} epitaxial thin film was characterized in oxygen, nitrogen and 4% hydrogen over a wide range of temperature from 400�C up to 800�C. To determine the electrode performance and oxygen exchange kinetics of PrBaCo{sub 2}O{sub 5+{delta}}, multi-layered thin film based half cell was deposited on LaAlO{sub 3}(001) substrate. The temperature dependence of the resistance of this half ?cell structure was characterized by electrochemical impedance spectroscopy (EIS) within different temperature and gas environments. Anode supported fuel cells, with GCO:YSZ multilayer thin film as electrolyte and PBCO thin film as electrode, are fabricated on tape casted NiO/YSZ substrate. Full cell performance is characterized up to 800�C.

  3. The temperature dependence of the three-body reaction rate coefficient for some rare-gas atomic ion-atom reactions in the range 100-300K

    International Nuclear Information System (INIS)

    The temperature dependence of some three-body association reaction rate coefficients for some rare-gas atomic ion-rare-gas atom reactions of the type A+ + 2B → AB+ + B have been investigated in the temperature range 100-300 K using a selected ion flow tube technique. The experimental method consists of injecting the ion A+ into the flowing carrier gas B and monitoring the ratio of the concentrations of AB+ to A+ as a function of carrier gas pressure. The three-body association rate coefficients are obtained from an analysis which allows for differential diffusive losses and reaction with impurities in a limited manner. (author)

  4. An investigation of the effect of the upper beryllium reflector on the moderator temperature coefficient of reactivity of miniature neutron source reactors

    Energy Technology Data Exchange (ETDEWEB)

    Binh, Do Quang [Univ. of Technical Education, Ho Chi Minh City (Viet Nam); Hai, Nguyen Hoang [Centre for Research and Development of Radiation Technology, Ho Chi Minh City (Viet Nam)

    2014-11-15

    In this paper, an investigation on the dependence of the effective multiplication factor, k{sub eff}, on moderator temperature for various thicknesses of the upper beryllium reflector in reactor conditions with different fuel burnups for the Miniature Neutron Source Reactor is carried out. Based on the linear dependence of k{sub eff} on moderator temperature, an approach to calculate the moderator temperature coefficient of reactivity, α{sub T}, at different temperatures and its average value, anti α{sub T}, in a range of temperatures directly through the moderator temperature is developed. Calculations are performed to evaluate the effect of change in the upper reflector thickness on the moderator temperature coefficient of reactivity for the fresh core and reactor conditions with different fuel burnups. Calculated results indicate that anti α{sub T} increases with the increased beryllium thickness, but decreases with the increasing fuel burnup. Analysis of calculated results provides an additional insight into the relation of the upper reflector thickness, the neutron energy spectrum in the reactor core, and the moderator temperature coefficient of reactivity.

  5. Optimization and experimental validation of a thermal cycle that maximizes entropy coefficient fisher identifiability for lithium iron phosphate cells

    Science.gov (United States)

    Mendoza, Sergio; Rothenberger, Michael; Hake, Alison; Fathy, Hosam

    2016-03-01

    This article presents a framework for optimizing the thermal cycle to estimate a battery cell's entropy coefficient at 20% state of charge (SOC). Our goal is to maximize Fisher identifiability: a measure of the accuracy with which a parameter can be estimated. Existing protocols in the literature for estimating entropy coefficients demand excessive laboratory time. Identifiability optimization makes it possible to achieve comparable accuracy levels in a fraction of the time. This article demonstrates this result for a set of lithium iron phosphate (LFP) cells. We conduct a 24-h experiment to obtain benchmark measurements of their entropy coefficients. We optimize a thermal cycle to maximize parameter identifiability for these cells. This optimization proceeds with respect to the coefficients of a Fourier discretization of this thermal cycle. Finally, we compare the estimated parameters using (i) the benchmark test, (ii) the optimized protocol, and (iii) a 15-h test from the literature (by Forgez et al.). The results are encouraging for two reasons. First, they confirm the simulation-based prediction that the optimized experiment can produce accurate parameter estimates in 2 h, compared to 15-24. Second, the optimized experiment also estimates a thermal time constant representing the effects of thermal capacitance and convection heat transfer.

  6. Temperature Effects on the Photovoltaic Performance of Planar Structure Perovskite Solar Cells

    OpenAIRE

    Cojocaru, Ludmila; Uchida, Satoshi; Sanehira, Yoshitaka; González Pedro, Victoria; Bisquert, Juan; Nakazaki, Jotaro; Kubo, Takaya; Segawa, Hiroshi

    2015-01-01

    Temperature effects of CH3NH3PbI3 perovskite solar cells having simple planar architecture were investigated on the crystal structure and photovoltaic performance. The obvious changes in the CH3NH3PbI3 crystal structure were found by varying the temperature as a consequence to the augmentation in lattice parameters and expansion of the unit cell. The expansion of the crystal gave a serious influence on the performance of the solar cells, where the differences in the coefficients of the therma...

  7. Densities, Excess Molar Volumes, and Thermal Expansion Coefficients of Aqueous Aminoethylethanolamine Solutions at Temperatures from 283.15 to 343.15 K.

    Science.gov (United States)

    Stec, Marcin; Tatarczuk, Adam; Spiewak, Dariusz; Wilk, Andrzej

    2014-01-01

    The densities of aqueous mixtures of aminoethylethanolamine (CAS #000111-41-1) were measured over the entire compositional range at temperatures of 283.15-343.15 K. The results of these measurements were used to calculate excess molar volumes and isobaric thermal expansion coefficients, and partial molar and apparent molar volumes and excess isobaric thermal expansion coefficients were subsequently derived. The excess molar volumes were correlated as a function of the mole fraction using the Redlich-Kister equation. Temperature dependences of the Redlich-Kister coefficients are also presented. The partial molar volumes at infinite dilution of AEEA in water were determined using two different methods. In addition, the solution density was correlated using a Joubian-Acree model. Aqueous solutions of AEEA exhibit similar properties to the aqueous solutions of other alkanolamines (like monoethanolamine) used in acid gas sweetening. PMID:24899753

  8. Diffusion coefficients of fission products in the UO sub 2 kernel and pyrocarbon layer of BISO-coated fuel particles at extremely high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Kimio; Fukuda, Kousaku (Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan))

    1990-11-01

    Release of metal fission products from pyrocarbon (PyC) coated UO{sub 2} particles was studied by post-irradiation annealing at temperatures from 1600 to 2300deg C. Release of {sup 106}Ru and {sup 155}Eu was controlled by diffusion in the kernel at temperatures above 1800deg C, and their reduced diffusion coefficients in the kernel were very close to each other. The diffusion coefficient of Cs, D{sub Cs} (m{sup 2}/s), in the PyC layer was determined from the fractional release, as follows: D{sub Cs}=1.2x10{sup -3} exp(-4.12x10{sup 5} (J/mol)/RT), which was larger than that of Ce by an order of magnitude. The diffusion coefficients of fission products in the PyC layer was discussed in terms of their ionic radii and stability of their carbides. (orig.).

  9. Diffusion coefficients of fission products in the UO2 kernel and pyrocarbon layer of BISO-coated fuel particles at extremely high temperatures

    International Nuclear Information System (INIS)

    Release of metal fission products from pyrocarbon (PyC) coated UO2 particles was studied by post-irradiation annealing at temperatures from 1600 to 2300deg C. Release of 106Ru and 155Eu was controlled by diffusion in the kernel at temperatures above 1800deg C, and their reduced diffusion coefficients in the kernel were very close to each other. The diffusion coefficient of Cs, DCs (m2/s), in the PyC layer was determined from the fractional release, as follows: DCs=1.2x10-3 exp[-4.12x105 (J/mol)/RT], which was larger than that of Ce by an order of magnitude. The diffusion coefficients of fission products in the PyC layer was discussed in terms of their ionic radii and stability of their carbides. (orig.)

  10. Yeast cells proliferation on various strong static magnetic fields and temperatures

    Science.gov (United States)

    Otabe, E. S.; Kuroki, S.; Nikawa, J.; Matsumoto, Y.; Ooba, T.; Kiso, K.; Hayashi, H.

    2009-03-01

    The effect of strong magnetic fields on activities of yeast cells were investigated. Experimental yeast cells were cultured in 5 ml of YPD(Yeast extract Peptone Dextrose) for the number density of yeast cells of 5.0 ±0.2 x 106/ml with various temperatures and magnetic fields up to 10 T. Since the yeast cells were placed in the center of the superconducting magnet, the effect of magnetic force due to the diamagnetism and magnetic gradient was negligibly small. The yeast suspension was opened to air and cultured in shaking condition. The number of yeast cells in the yeast suspension was counted by a counting plate with an optical microscope, and the time dependence of the number density of yeast cells was measured. The time dependence of the number density of yeast cells, ρ, of initial part is analyzed in terms of Malthus equation as given by ρ = ρo exp(kt), where k is the growth coefficient. It is found that, the growth coefficient under the magnetic field is suppressed compared with the control. The growth coefficient decreasing as increasing magnetic field and is saturated at about 5 T. On the other hand, it is found that the suppression of growth of yeast cells by the magnetic field is diminished at high temperatures.

  11. Yeast cells proliferation on various strong static magnetic fields and temperatures

    International Nuclear Information System (INIS)

    The effect of strong magnetic fields on activities of yeast cells were investigated. Experimental yeast cells were cultured in 5 ml of YPD(Yeast extract Peptone Dextrose) for the number density of yeast cells of 5.0 ±0.2 x 106/ml with various temperatures and magnetic fields up to 10 T. Since the yeast cells were placed in the center of the superconducting magnet, the effect of magnetic force due to the diamagnetism and magnetic gradient was negligibly small. The yeast suspension was opened to air and cultured in shaking condition. The number of yeast cells in the yeast suspension was counted by a counting plate with an optical microscope, and the time dependence of the number density of yeast cells was measured. The time dependence of the number density of yeast cells, ρ, of initial part is analyzed in terms of Malthus equation as given by ρ = ρo exp(kt), where k is the growth coefficient. It is found that, the growth coefficient under the magnetic field is suppressed compared with the control. The growth coefficient decreasing as increasing magnetic field and is saturated at about 5 T. On the other hand, it is found that the suppression of growth of yeast cells by the magnetic field is diminished at high temperatures.

  12. Large exponential gain coefficient in polymer assisted asymmetric liquid crystal cells originating from surface effect

    Science.gov (United States)

    Fu, Jiayin; Zhang, Jingwen; Xue, Tingyu; Zhao, Hua

    2016-09-01

    As large as 4607 cm-1 gain coefficient in two beam coupling experiment was obtained by introducing PVK:C60 film to ZnSe assisted liquid crystal system. As short as 5.0 ms holographic recording time was reached when probing the grating formation process, showing great potential in real time applications. Systematical two beam coupling and grating probing experiments were performed in studying the mechanism behind the high photorefractive (PR) performance. Unusual energy transfer direction change and gain coefficient fluctuation were observed when the voltage polarity and incidence side were altered in the related two wave coupling experiments.

  13. Seebeck coefficients in ionic liquids--prospects for thermo-electrochemical cells.

    Science.gov (United States)

    Abraham, Theodore J; MacFarlane, Douglas R; Pringle, Jennifer M

    2011-06-14

    Measurement of Seebeck coefficients in a range of ionic liquids (ILs) suggests that these electrolytes could enable the development of thermoelectric devices to generate electrical energy from low-grade heat in the 100-150 °C range. PMID:21544302

  14. Communication: Rigorous quantum dynamics of O + O{sub 2} exchange reactions on an ab initio potential energy surface substantiate the negative temperature dependence of rate coefficients

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yaqin; Sun, Zhigang, E-mail: zsun@dicp.ac.cn, E-mail: dawesr@mst.edu, E-mail: hguo@unm.edu [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023 (China); Center for Advanced Chemical Physics, University of Science and Technology of China, 96 Jinzhai Road, Hefei 230026 (China); Jiang, Bin; Guo, Hua, E-mail: zsun@dicp.ac.cn, E-mail: dawesr@mst.edu, E-mail: hguo@unm.edu [Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Xie, Daiqian [Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Dawes, Richard, E-mail: zsun@dicp.ac.cn, E-mail: dawesr@mst.edu, E-mail: hguo@unm.edu [Department of Chemistry, Missouri University of Science and Technology, Rolla, Missouri 65409 (United States)

    2014-08-28

    The kinetics and dynamics of several O + O{sub 2} isotope exchange reactions have been investigated on a recently determined accurate global O{sub 3} potential energy surface using a time-dependent wave packet method. The agreement between calculated and measured rate coefficients is significantly improved over previous work. More importantly, the experimentally observed negative temperature dependence of the rate coefficients is for the first time rigorously reproduced theoretically. This negative temperature dependence can be attributed to the absence in the new potential energy surface of a submerged “reef” structure, which was present in all previous potential energy surfaces. In addition, contributions of rotational excited states of the diatomic reactant further accentuate the negative temperature dependence.

  15. Communication: Rigorous quantum dynamics of O + O2 exchange reactions on an ab initio potential energy surface substantiate the negative temperature dependence of rate coefficients

    International Nuclear Information System (INIS)

    The kinetics and dynamics of several O + O2 isotope exchange reactions have been investigated on a recently determined accurate global O3 potential energy surface using a time-dependent wave packet method. The agreement between calculated and measured rate coefficients is significantly improved over previous work. More importantly, the experimentally observed negative temperature dependence of the rate coefficients is for the first time rigorously reproduced theoretically. This negative temperature dependence can be attributed to the absence in the new potential energy surface of a submerged “reef” structure, which was present in all previous potential energy surfaces. In addition, contributions of rotational excited states of the diatomic reactant further accentuate the negative temperature dependence

  16. Dose conversion coefficients for monoenergetic electrons incident on a realistic human eye model with different lens cell populations

    Energy Technology Data Exchange (ETDEWEB)

    Nogueira, P; Vaz, P [Technological and Nuclear Institute, Estrada Nacional No 10, 2686-953 Sacavem (Portugal); Zankl, M; Schlattl, H, E-mail: pedro.nogueira@helmholtz-muenchen.de [Helmholtz Zentrum Muenchen-German Research Center for Environmental Health, Research Unit Medical Radiation Physics and Diagnostics, Ingolstaedter Landstrasse 1, D-85764 Neuherberg (Germany)

    2011-11-07

    The radiation-induced posterior subcapsular cataract has long been generally accepted to be a deterministic effect that does not occur at doses below a threshold of at least 2 Gy. Recent epidemiological studies indicate that the threshold for cataract induction may be much lower or that there may be no threshold at all. A thorough study of this subject requires more accurate dose estimates for the eye lens than those available in ICRP Publication 74. Eye lens absorbed dose per unit fluence conversion coefficients for electron irradiation were calculated using a geometrical model of the eye that takes into account different cell populations of the lens epithelium, together with the MCNPX Monte Carlo radiation transport code package. For the cell population most sensitive to ionizing radiation-the germinative cells-absorbed dose per unit fluence conversion coefficients were determined that are up to a factor of 4.8 higher than the mean eye lens absorbed dose conversion coefficients for electron energies below 2 MeV. Comparison of the results with previously published values for a slightly different eye model showed generally good agreement for all electron energies. Finally, the influence of individual anatomical variability was quantified by positioning the lens at various depths below the cornea. A depth difference of 2 mm between the shallowest and the deepest location of the germinative zone can lead to a difference between the resulting absorbed doses of up to nearly a factor of 5000 for electron energy of 0.7 MeV.

  17. Dose conversion coefficients for monoenergetic electrons incident on a realistic human eye model with different lens cell populations

    International Nuclear Information System (INIS)

    The radiation-induced posterior subcapsular cataract has long been generally accepted to be a deterministic effect that does not occur at doses below a threshold of at least 2 Gy. Recent epidemiological studies indicate that the threshold for cataract induction may be much lower or that there may be no threshold at all. A thorough study of this subject requires more accurate dose estimates for the eye lens than those available in ICRP Publication 74. Eye lens absorbed dose per unit fluence conversion coefficients for electron irradiation were calculated using a geometrical model of the eye that takes into account different cell populations of the lens epithelium, together with the MCNPX Monte Carlo radiation transport code package. For the cell population most sensitive to ionizing radiation-the germinative cells-absorbed dose per unit fluence conversion coefficients were determined that are up to a factor of 4.8 higher than the mean eye lens absorbed dose conversion coefficients for electron energies below 2 MeV. Comparison of the results with previously published values for a slightly different eye model showed generally good agreement for all electron energies. Finally, the influence of individual anatomical variability was quantified by positioning the lens at various depths below the cornea. A depth difference of 2 mm between the shallowest and the deepest location of the germinative zone can lead to a difference between the resulting absorbed doses of up to nearly a factor of 5000 for electron energy of 0.7 MeV.

  18. Transformation of the band spectrum of Hg-based HTSC and features of the temperature dependences of the thermoelectric power coefficient

    Science.gov (United States)

    Babych, O. Y.; Boyko, Ya. V.

    2014-03-01

    The temperature variations of the thermoelectric power coefficients of the Hg-based high-temperature superconductors HgBa2Can-1CunO2n+2+δ (n = 1, 2, 3) with oxygen doping and cation substitutions are analyzed in terms of a narrow conduction band model. The parameters of the band spectrum in the vicinity of the Fermi level are determined and the manner in which they transform is examined. A correlation is found between the effective band width and the superconducting transition temperature Tc.

  19. Disorder effect on heat capacity, self-diffusion coefficient, and choosing best potential model for melting temperature, in gold–copper bimetallic nanocluster with 55 atoms

    International Nuclear Information System (INIS)

    Molecular dynamics simulation has been implemented for doping effect on melting temperature, heat capacity, self-diffusion coefficient of gold–copper bimetallic nanostructure with 55 total gold and copper atom numbers and its bulk alloy. Trend of melting temperature for gold–copper bimetallic nanocluster is not same as melting temperature copper–gold bulk alloy. Molecular dynamics simulation of our result regarding bulk melting temperature is consistence with available experimental data. Molecular dynamics simulation shows that melting temperature of gold–copper bimetallic nanocluster increases with copper atom fraction. Semi-empirical potential model and quantum Sutton–Chen potential models do not change melting temperature trend with copper doping of gold–copper bimetallic nanocluster. Self-diffusion coefficient of copper atom is greater than gold atom in gold–copper bimetallic nanocluster. Semi-empirical potential within the tight-binding second moment approximation as new application potential model for melting temperature of gold–copper bulk structure shows better result in comparison with EAM, Sutton–Chen potential, and quantum Sutton–Chen potential models

  20. Sommerfeld coefficient of δ-Pu determined via a low-temperature specific heat Pu-Ce study

    Czech Academy of Sciences Publication Activity Database

    Havela, L.; Javorský, P.; Shick, Alexander; Kolorenč, Jindřich; Colineau, E.; Rebizant, J.; Wastin, F.; Griveau, J.C.; Jolly, L.; Texier, G.; Delaunay, F.; Baclet, N.

    2010-01-01

    Roč. 82, č. 15 (2010), 155140/1-155140/5. ISSN 1098-0121 R&D Projects: GA ČR(CZ) GAP204/10/0330 Institutional research plan: CEZ:AV0Z10100520 Keywords : Sommerfeld coefficient γ * δ-Pu Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.772, year: 2010

  1. Influence of wall emissivity and convective heat transfer coefficient on the adiabatic surface temperature as thermal/structural parameter in fire modeling

    International Nuclear Information System (INIS)

    In fire engineering analysis, one of the open problem is the transfer of thermal parameters obtained by fire CFD model to FEM models for structural analysis. In this study the new useful concept of “Adiabatic Surface Temperature” or more commonly known as AST, introduced by Wickström, is investigated. The adiabatic surface temperature offers the opportunity to transfer both thermal information of the gas and the net heat flux to the solid phase model, obtained by CFD analysis. In this study two CFD analyses are carried out in order to evaluate the effect of emissivity and of convective heat transfer coefficient to determine the AST. First one CFD analysis simulating a fire scenario, “conjugate heat transfer”, with a square steel beam exposed to hot surface is carried out to calculate AST, heat convective coefficient and temperature field in the beam. Second one, a conductive analysis is carried out on “standalone beam” imposing a third type boundary condition on its boundaries assuming the AST, evaluated in the conjugate analysis, as external temperature. Different heat convective coefficients are imposed on the beam walls. The comparison between results obtained by means of the two proposed analyses shows the use of AST as transfer thermal parameter between CFD (Computational Fluid Dynamic) and FEM (Finite Element Method) models is appropriate when the convective heat transfer coefficient is properly evaluated. -- Highlights: ► An open problem is to transfer parameters obtained by thermal to structural models. ► The useful concept of “Adiabatic Surface Temperature” (AST) is investigated. ► The AST use is right for properly evaluated convective heat transfer coefficient

  2. 低温感高能硝胺发射药的实验研究%Experiments on the Low Temperature Sensitivity Coefficient High-Energy Nitroamine Propellant

    Institute of Scientific and Technical Information of China (English)

    史先扬; 王泽山

    2001-01-01

    通过中止试验、高压密闭爆发器试验与火炮内弹道试验研究了低温感高能硝胺发射药的低温感效果。结果表明,低温感装药技术用于高能硝胺发射药能够大幅度降低火炮温度系数,提高火炮能量利用率。%Studied the low temperature sensitivity coefficient (LTSC) effect on high-energy nitroamine propellant throgh the termination experiment,closed bomb experiment and interior ballistic experiment.The results show that the LTSC charge technology can decrease temperature sensitivity coefficient and improve energy utilization ratio of gun.

  3. Infinite-dilution solute partition coefficients in a room-temperature ionic liquid-CO2 system from supercritical fluid chromatography

    Czech Academy of Sciences Publication Activity Database

    Planeta, Josef; Roth, Michal

    Beijing: Chinese Chemical Society, 2004, s. 151. [ICCT 2004. The 18th IUPAC Conference on Chemical Thermodynamics. Beijing (CN), 17.08.2004-21.08.2004] R&D Projects: GA ČR GA203/02/1093; GA AV ČR IAA4031301 Institutional research plan: CEZ:AV0Z4031919 Keywords : room-temperature ionic liquid * solute partition coefficient * supercritical carbon dioxide Subject RIV: CF - Physical ; Theoretical Chemistry

  4. Calculation of the radial and axial diffusion coefficient for a hexagonal lattice of a high-temperature reactor with block elements

    International Nuclear Information System (INIS)

    A numerical method for the calculation of the radial and axial diffusion coefficient for the hexagonal lattice of a high-temperature reactor with block elements is developed. Results for a typical lattice are given and a comparison with the formulas of Behrens and Benoist is made. A modification of Benoist's formulas for a tightly packed lattice that gives a better agreement with the numerical results is proposed. 9 refs

  5. In Vitro Assessment of Factors Affecting the Apparent Diffusion Coefficient of Ramos Cells Using Bio-phantoms

    Directory of Open Access Journals (Sweden)

    Sasaki,Takanori

    2012-06-01

    Full Text Available The roles of cell density, extracellular space, intracellular factors, and apoptosis induced by the molecularly targeted drug rituximab on the apparent diffusion coefficient (ADC values were investigated using bio-phantoms. In these bio-phantoms, Ramos cells (a human Burkittセs lymphoma cell line were encapsulated in gellan gum. The ADC values decreased linearly with the increase in cell density, and declined steeply when the extracellular space became less than 4 μm. The analysis of ADC values after destruction of the cellular membrane by sonication indicated that approximately 65% of the ADC values of normal cells originate from the cell structures made of membranes and that the remaining 35% originate from intracellular components. Microparticles, defined as particles smaller than the normal cells, increased in number after rituximab treatments, migrated to the extracellular space and significantly decreased the ADC values of bio-phantoms during apoptosis. An in vitro study using bio-phantoms was conducted to quantitatively clarify the roles of cellular factors and of extracellular space in determining the ADC values yielded by tumor cells and the mechanism by which apoptosis changes those values.

  6. Temperature coefficient of piezoelectric constants in Pb(Mg1/3 Nb2/3O3 - PbTiO3 ceramics

    Directory of Open Access Journals (Sweden)

    Manuel Henrique Lente

    2004-06-01

    Full Text Available In this work, the thermal stability of piezoelectric constants of PMN-PT ceramics in the tetragonal and rhombohedral phases were investigated in a wide range of temperatures. The results showed that the tetragonal PMN-PT presented higher thermal stability and, consequently, the temperature coefficients for the piezoelectric constants were approximately zero. This result revealed to be much better than that commonly found for PZT ceramics. Although the rhombohedral PMN-PT presented a slight lower thermal stability, the values found for the coupling factor were significantly higher than the tetragonal composition.

  7. Magneto Transport of high TCR (temperature coefficient of resistance) La2/3Ca1/3MnO3: Ag Polycrystalline Composites

    OpenAIRE

    Awana, V. P. S.; Tripathi, Rahul; Balamurugan, S.; Kishan, H.; Takayama-Muromachi, E.

    2006-01-01

    We report the synthesis, (micro)structural, magneto-transport and magnetization of polycrystalline La2/3Ca1/3MnO3:Agx composites with x = 0.0, 0.1, 0.2, 0.3 and 0.4. The temperature coefficient of resistance (TCR) near ferromagnetic (FM) transition is increased significantly with addition of Ag. The FM transition temperature (TFM) is also increased slightly with Ag addition. Magneto-transport measurements revealed that magneto-resistance MR is found to be maximum near TFM. Further the increas...

  8. The Effect of Temperature on Kinetics and Diffusion Coefficients of Metallocene Derivatives in Polyol-Based Deep Eutectic Solvents

    OpenAIRE

    Laleh Bahadori; Mohammed Harun Chakrabarti; Ninie Suhana Abdul Manan; Mohd Ali Hashim; Farouq Sabri Mjalli; Inas Muen AlNashef; Nigel Brandon

    2015-01-01

    The temperature dependence of the density, dynamic viscosity and ionic conductivity of several deep eutectic solvents (DESs) containing ammonium-based salts and hydrogen bond donvnors (polyol type) are investigated. The temperature-dependent electrolyte viscosity as a function of molar conductivity is correlated by means of Walden's rule. The oxidation of ferrocene (Fc/Fc+) and reduction of cobaltocenium (Cc+/Cc) at different temperatures are studied by cyclic voltammetry and potential-step c...

  9. Low temperature rate coefficients of the H + CH+ → C+ + H2 reaction: New potential energy surface and time-independent quantum scattering

    International Nuclear Information System (INIS)

    The observed abundances of the methylidyne cation, CH+, in diffuse molecular clouds can be two orders of magnitude higher than the prediction of the standard gas-phase models which, in turn, predict rather well the abundances of neutral CH. It is therefore necessary to investigate all the possible formation and destruction processes of CH+ in the interstellar medium with the most abundant species H, H2, and e−. In this work, we address the destruction process of CH+ by hydrogen abstraction. We report a new calculation of the low temperature rate coefficients for the abstraction reaction, using accurate time-independent quantum scattering and a new high-level ab initio global potential energy surface including a realistic model of the long-range interaction between the reactants H and CH+. The calculated thermal rate coefficient is in good agreement with the experimental data in the range 50 K–800 K. However, at lower temperatures, the experimental rate coefficient takes exceedingly small values which are not reproduced by the calculated rate coefficient. Instead, the latter rate coefficient is close to the one given by the Langevin capture model, as expected for a reaction involving an ion and a neutral species. Several recent theoretical works have reported a seemingly good agreement with the experiment below 50 K, but an analysis of these works show that they are based on potential energy surfaces with incorrect long-range behavior. The experimental results were explained by a loss of reactivity of the lowest rotational states of the reactant; however, the quantum scattering calculations show the opposite, namely, a reactivity enhancement with rotational excitation

  10. Low temperature rate coefficients of the H + CH(+) → C(+) + H2 reaction: New potential energy surface and time-independent quantum scattering.

    Science.gov (United States)

    Werfelli, Ghofran; Halvick, Philippe; Honvault, Pascal; Kerkeni, Boutheïna; Stoecklin, Thierry

    2015-09-21

    The observed abundances of the methylidyne cation, CH(+), in diffuse molecular clouds can be two orders of magnitude higher than the prediction of the standard gas-phase models which, in turn, predict rather well the abundances of neutral CH. It is therefore necessary to investigate all the possible formation and destruction processes of CH(+) in the interstellar medium with the most abundant species H, H2, and e(-). In this work, we address the destruction process of CH(+) by hydrogen abstraction. We report a new calculation of the low temperature rate coefficients for the abstraction reaction, using accurate time-independent quantum scattering and a new high-level ab initio global potential energy surface including a realistic model of the long-range interaction between the reactants H and CH(+). The calculated thermal rate coefficient is in good agreement with the experimental data in the range 50 K-800 K. However, at lower temperatures, the experimental rate coefficient takes exceedingly small values which are not reproduced by the calculated rate coefficient. Instead, the latter rate coefficient is close to the one given by the Langevin capture model, as expected for a reaction involving an ion and a neutral species. Several recent theoretical works have reported a seemingly good agreement with the experiment below 50 K, but an analysis of these works show that they are based on potential energy surfaces with incorrect long-range behavior. The experimental results were explained by a loss of reactivity of the lowest rotational states of the reactant; however, the quantum scattering calculations show the opposite, namely, a reactivity enhancement with rotational excitation. PMID:26395702

  11. MM98.04 Measurement of temperature and determination of heat transfer coefficient in backward can extrusion

    DEFF Research Database (Denmark)

    Henningsen, Poul; Hattel, Jesper Henri; Wanheim, Tarras

    1998-01-01

    Temperature is measured during backward can extrusion of steel. The process is characterised by large deformations and very high surface pressure. In the experiments, a can in low carbon steel with a lubrication layer of phosphate soap is formed. The temperature is measured by thermocouples in the...

  12. MM98.34 Experimental Measurements of Die temperatures and determination of heat transfer coefficient in backward can extrusion

    DEFF Research Database (Denmark)

    Henningsen, Poul; Hattel, Jesper Henri; Wanheim, Tarras

    1998-01-01

    The large deformations in backward can extrusion result in a rise of temperature of more than 200 degrees Centigrade. In the experiments cans in low carbon steel are formed, with a lubrication layer of phosphate soap. The temperature is measured by thermocouples in the die insert and the punch. The...

  13. The Effect of Temperature on Kinetics and Diffusion Coefficients of Metallocene Derivatives in Polyol-Based Deep Eutectic Solvents.

    Directory of Open Access Journals (Sweden)

    Laleh Bahadori

    Full Text Available The temperature dependence of the density, dynamic viscosity and ionic conductivity of several deep eutectic solvents (DESs containing ammonium-based salts and hydrogen bond donvnors (polyol type are investigated. The temperature-dependent electrolyte viscosity as a function of molar conductivity is correlated by means of Walden's rule. The oxidation of ferrocene (Fc/Fc+ and reduction of cobaltocenium (Cc+/Cc at different temperatures are studied by cyclic voltammetry and potential-step chronoamperometry in DESs. For most DESs, chronoamperometric transients are demonstrated to fit an Arrhenius-type relation to give activation energies for the diffusion of redox couples at different temperatures. The temperature dependence of the measured conductivities of DES1 and DES2 are better correlated with the Vogel-Tamman-Fulcher equation. The kinetics of the Fc/Fc+ and Cc+/Cc electrochemical systems have been investigated over a temperature range from 298 to 338 K. The heterogeneous electron transfer rate constant is then calculated at different temperatures by means of a logarithmic analysis. The glycerol-based DES (DES5 appears suitable for further testing in electrochemical energy storage devices.

  14. The Effect of Temperature on Kinetics and Diffusion Coefficients of Metallocene Derivatives in Polyol-Based Deep Eutectic Solvents.

    Science.gov (United States)

    Bahadori, Laleh; Chakrabarti, Mohammed Harun; Manan, Ninie Suhana Abdul; Hashim, Mohd Ali; Mjalli, Farouq Sabri; AlNashef, Inas Muen; Brandon, Nigel

    2015-01-01

    The temperature dependence of the density, dynamic viscosity and ionic conductivity of several deep eutectic solvents (DESs) containing ammonium-based salts and hydrogen bond donvnors (polyol type) are investigated. The temperature-dependent electrolyte viscosity as a function of molar conductivity is correlated by means of Walden's rule. The oxidation of ferrocene (Fc/Fc+) and reduction of cobaltocenium (Cc+/Cc) at different temperatures are studied by cyclic voltammetry and potential-step chronoamperometry in DESs. For most DESs, chronoamperometric transients are demonstrated to fit an Arrhenius-type relation to give activation energies for the diffusion of redox couples at different temperatures. The temperature dependence of the measured conductivities of DES1 and DES2 are better correlated with the Vogel-Tamman-Fulcher equation. The kinetics of the Fc/Fc+ and Cc+/Cc electrochemical systems have been investigated over a temperature range from 298 to 338 K. The heterogeneous electron transfer rate constant is then calculated at different temperatures by means of a logarithmic analysis. The glycerol-based DES (DES5) appears suitable for further testing in electrochemical energy storage devices. PMID:26642045

  15. Multispectrum measurements of spectral line parameters including temperature dependences of N2- and self-broadened half-width coefficients in the region of the ν9 band of 12C2H6

    International Nuclear Information System (INIS)

    Ethane is a prominent contributor to the spectrum of Titan, particularly in the ν9 region centered near 822 cm-1. To improve the spectroscopic line parameters at 12 μm, 41 high-resolution (0.0016-0.005 cm-1) absorption spectra of C2H6 were obtained at sample temperatures between 211 and 298 K with the Bruker IFS 120HR at the Pacific Northwest National Laboratory (PNNL) in Richland, Washington. Two additional spectra were later recorded at ∼150 K using a new temperature-stabilized cryogenic cell designed for the sample compartment of the Bruker IFS 125HR at the Jet Propulsion Laboratory (JPL) in Pasadena, California. A multispectrum nonlinear least-squares fitting program was applied simultaneously to all 43 spectra to measure the line positions, intensities, N2- and self-broadened half-width coefficients and their temperature dependences. Reliable pressure-induced shift coefficients could not be obtained, however, because of the high congestion of spectral lines (due to torsional-split components, hot-band transitions as well as blends). Existing theoretical modeling of this very complicated ν9 region permitted effective control of the multispectrum fitting technique; some constraints were applied using predicted intensity ratios, doublet separations, half-width coefficients and their temperature dependence exponents in order to determine reliable parameters for each of the two torsional-split components. For 12C2H6, the resulting retrievals included 17 pQ and rQ sub-bands of ν9 (as well as some pP, rR sub-bands). Positions and intensities were measured for 3771 transitions, and a puzzling difference between previously measured ν9 intensities was clarified. In addition, line positions and intensities were obtained for two 12C2H6 hot bands (ν9+ν4-ν4, ν9+2ν4-2ν4) and the ν9 band of 13C12CH6, as well as several hundred presently unidentified transitions. N2- and self-broadened half-width coefficients were determined for over 1700 transitions, along with

  16. An Experimental Cell for High-Temperature

    Science.gov (United States)

    Giordano, D.; Robert, G.; Rodway, R.; Rust, A.; Russell, J. K.

    2005-12-01

    The Volcanology-Deformation-Rig (VDR) was developed for exploring the high-T rheological properties of volcanic materials [1]. The VDR is designed to perform high-T, low-load (< 1136 kg) deformation experiments at constant load, or displacement rate, or at controlled load rates. The rig is ideal for determining the rheological response of volcanic products within a wide range of natural conditions: T up to 1000oC, applied stresses up to 150 MPa, and strain rates between 10-6 and 10-2 s-1. The resulting data provide a powerful means of developing constitutive equations governing the multiphase (liquids ± vesicles ± solids) rheology of volcanic material during flow and deformation [2]. Many seminal issues in volcanology involve the behaviour of the volatile phase during flow and deformation and its effect on magma rheology and volcanic behaviour. Thus, we have designed and built a high-T resistant, sealed fluid pressure cell. The cell gives us the capacity to run controlled high-T deformation experiments at controlled H2O pressures that simulate nature (0-150 MPa). Deformation experiments can be run on consolidated and unconsolidated samples up to 3 cm in diameter and 10 cm in length. Fluid pressure in the cell can either be a dependent or independent variable. The former corresponds to a closed-system where fluid pressure is monitored throughout the experiment, whereas the latter is an open-system experiment with a fixed fluid pressure. By means of varying temperature and strain rate our experiments can explore the viscous to brittle transition of the investigated volcanic products at controlled conditions (e.g., water-bearing and/or water pressurized systems). We plan to use high-T experiments on natural volcanic materials (e.g., cores of sintered ash, obsidian, or pumice) to elucidate the rheology of multiphase volcanic products and to study feedback mechanisms between porosity and permeability evolution. References Cited: [1] Quane S, Russell JK & Kennedy LA

  17. Improving Accuracy in Arrhenius Models of Cell Death: Adding a Temperature-Dependent Time Delay.

    Science.gov (United States)

    Pearce, John A

    2015-12-01

    The Arrhenius formulation for single-step irreversible unimolecular reactions has been used for many decades to describe the thermal damage and cell death processes. Arrhenius predictions are acceptably accurate for structural proteins, for some cell death assays, and for cell death at higher temperatures in most cell lines, above about 55 °C. However, in many cases--and particularly at hyperthermic temperatures, between about 43 and 55 °C--the particular intrinsic cell death or damage process under study exhibits a significant "shoulder" region that constant-rate Arrhenius models are unable to represent with acceptable accuracy. The primary limitation is that Arrhenius calculations always overestimate the cell death fraction, which leads to severely overoptimistic predictions of heating effectiveness in tumor treatment. Several more sophisticated mathematical model approaches have been suggested and show much-improved performance. But simpler models that have adequate accuracy would provide useful and practical alternatives to intricate biochemical analyses. Typical transient intrinsic cell death processes at hyperthermic temperatures consist of a slowly developing shoulder region followed by an essentially constant-rate region. The shoulder regions have been demonstrated to arise chiefly from complex functional protein signaling cascades that generate delays in the onset of the constant-rate region, but may involve heat shock protein activity as well. This paper shows that acceptably accurate and much-improved predictions in the simpler Arrhenius models can be obtained by adding a temperature-dependent time delay. Kinetic coefficients and the appropriate time delay are obtained from the constant-rate regions of the measured survival curves. The resulting predictions are seen to provide acceptably accurate results while not overestimating cell death. The method can be relatively easily incorporated into numerical models. Additionally, evidence is presented

  18. Diffusion Coefficient of Fluorescent Phosphatidylinositol 4,5-bisphosphate in the Plasma Membrane of Cells

    OpenAIRE

    Golebiewska, Urszula; Nyako, Marian; Woturski, William; Zaitseva, Irina; McLaughlin, Stuart

    2008-01-01

    Phosphatidylinositol 4,5-bisphosphate (PIP2) controls a surprisingly large number of processes in cells. Thus, many investigators have suggested that there might be different pools of PIP2 on the inner leaflet of the plasma membrane. If a significant fraction of PIP2 is bound electrostatically to unstructured clusters of basic residues on membrane proteins, the PIP2 diffusion constant, D, should be reduced. We microinjected micelles of Bodipy TMR-PIP2 into cells, and we measured D on the inne...

  19. Estimation of the effective intercellular diffusion coefficient in cell monolayers coupled by gap junctions

    DEFF Research Database (Denmark)

    Olesen, Niels Erik; Hofgaard, Johannes P; von Holstein-Rathlou, Niels-Henrik;

    2012-01-01

    A recently developed dye-based assay to study gap junction permeability is analysed. The assay is based on electroporation of dye into a large number of connexin 43 expressing cells, grown to confluency on electrically conductive slides. The subsequent intercellular spread of dye to non-electropo......A recently developed dye-based assay to study gap junction permeability is analysed. The assay is based on electroporation of dye into a large number of connexin 43 expressing cells, grown to confluency on electrically conductive slides. The subsequent intercellular spread of dye to non...

  20. Fluorinated and Non-Fluorinated Electro-Optic Copolymers: Determination of the Time and Temperature Stability of the Induced Electro-Optic Coefficient

    Directory of Open Access Journals (Sweden)

    Alessandro Belardini

    2012-10-01

    Full Text Available Organic fluorinated materials demonstrate their excellent electro-optic properties and versatility for technological applications. The partial substitution of hydrogen with fluorine in carbon-halides bounds allows the reduction of absorption losses at the telecommunication wavelengths. In these interesting compounds, the electro-optic coefficient was typically induced by a poling procedure. The magnitude and the time stability of the coefficient is an important issue to be investigated in order to compare copolymer species. Here, a review of different measurement techniques (such as nonlinear ellipsometry, second harmonic generation, temperature scanning and isothermal relaxation was shown and applied to a variety of fluorinated and non-fluorinated electro-optic compounds.

  1. Excellence of numerical differentiation method in calculating the coefficients of high temperature series expansion of the free energy and convergence problem of the expansion

    International Nuclear Information System (INIS)

    In this paper, it is shown that the numerical differentiation method in performing the coupling parameter series expansion [S. Zhou, J. Chem. Phys. 125, 144518 (2006); AIP Adv. 1, 040703 (2011)] excels at calculating the coefficients ai of hard sphere high temperature series expansion (HS-HTSE) of the free energy. Both canonical ensemble and isothermal-isobaric ensemble Monte Carlo simulations for fluid interacting through a hard sphere attractive Yukawa (HSAY) potential with extremely short ranges and at very low temperatures are performed, and the resulting two sets of data of thermodynamic properties are in excellent agreement with each other, and well qualified to be used for assessing convergence of the HS-HTSE for the HSAY fluid. Results of valuation are that (i) by referring to the results of a hard sphere square well fluid [S. Zhou, J. Chem. Phys. 139, 124111 (2013)], it is found that existence of partial sum limit of the high temperature series expansion series and consistency between the limit value and the true solution depend on both the potential shapes and temperatures considered. (ii) For the extremely short range HSAY potential, the HS-HTSE coefficients ai falls rapidly with the order i, and the HS-HTSE converges from fourth order; however, it does not converge exactly to the true solution at reduced temperatures lower than 0.5, wherein difference between the partial sum limit of the HS-HTSE series and the simulation result tends to become more evident. Something worth mentioning is that before the convergence order is reached, the preceding truncation is always improved by the succeeding one, and the fourth- and higher-order truncations give the most dependable and qualitatively always correct thermodynamic results for the HSAY fluid even at low reduced temperatures to 0.25

  2. 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.

  3. Effect of particle size on dc conductivity, activation energy and diffusion coefficient of lithium iron phosphate in Li-ion cells

    Directory of Open Access Journals (Sweden)

    T.V.S.L. Satyavani

    2016-03-01

    Full Text Available Cathode materials in nano size improve the performance of batteries due to the increased reaction rate and short diffusion lengths. Lithium Iron Phosphate (LiFePO4 is a promising cathode material for Li-ion batteries. However, it has its own limitations such as low conductivity and low diffusion coefficient which lead to high impedance due to which its application is restricted in batteries. In the present work, increase of conductivity with decreasing particle size of LiFePO4/C is studied. Also, the dependence of conductivity and activation energy for hopping of small polaron in LiFePO4/C on variation of particle size is investigated. The micro sized cathode material is ball milled for different durations to reduce the particle size to nano level. The material is characterized for its structure and particle size. The resistivities/dc conductivities of the pellets are measured using four probe technique at different temperatures, up to 150 °C. The activation energies corresponding to different particle sizes are calculated using Arrhenius equation. CR2032 cells are fabricated and electrochemical characteristics, namely, ac impedance and diffusion coefficients, are studied.

  4. Using Variable Temperature Powder X-Ray Diffraction to Determine the Thermal Expansion Coefficient of Solid MgO

    Science.gov (United States)

    Corsepius, Nicholas C.; DeVore, Thomas C.; Reisner, Barbara A.; Warnaar, Deborah L.

    2007-01-01

    A laboratory exercise was developed by using variable temperature powder X-ray diffraction (XRD) to determine [alpha] for MgO (periclase)and was tested in the Applied Physical Chemistry and Materials Characterization Laboratories at James Madison University. The experiment which was originally designed to provide undergraduate students with a…

  5. Tetrazole substituted polymers for high temperature polymer electrolyte fuel cells

    DEFF Research Database (Denmark)

    Henkensmeier, Dirk; My Hanh Duong, Ngoc; Brela, Mateusz;

    2015-01-01

    interesting for use in a high temperature fuel cell (HT PEMFC). Based on these findings, two polymers incorporating the proposed TZ groups were synthesised, formed into membranes, doped with PA and tested for fuel cell relevant properties. At room temperature, TZ-PEEN and commercial meta-PBI showed an...

  6. Controlled Delivery of Human Cells by Temperature Responsive Microcapsules

    Directory of Open Access Journals (Sweden)

    W.C. Mak

    2015-06-01

    Full Text Available Cell therapy is one of the most promising areas within regenerative medicine. However, its full potential is limited by the rapid loss of introduced therapeutic cells before their full effects can be exploited, due in part to anoikis, and in part to the adverse environments often found within the pathologic tissues that the cells have been grafted into. Encapsulation of individual cells has been proposed as a means of increasing cell viability. In this study, we developed a facile, high throughput method for creating temperature responsive microcapsules comprising agarose, gelatin and fibrinogen for delivery and subsequent controlled release of cells. We verified the hypothesis that composite capsules combining agarose and gelatin, which possess different phase transition temperatures from solid to liquid, facilitated the destabilization of the capsules for cell release. Cell encapsulation and controlled release was demonstrated using human fibroblasts as model cells, as well as a therapeutically relevant cell line—human umbilical vein endothelial cells (HUVECs. While such temperature responsive cell microcapsules promise effective, controlled release of potential therapeutic cells at physiological temperatures, further work will be needed to augment the composition of the microcapsules and optimize the numbers of cells per capsule prior to clinical evaluation.

  7. Burst annealing of high temperature GaAs solar cells

    Science.gov (United States)

    Brothers, P. R.; Horne, W. E.

    1991-01-01

    One of the major limitations of solar cells in space power systems is their vulnerability to radiation damage. One solution to this problem is to periodically heat the cells to anneal the radiation damage. Annealing was demonstrated with silicon cells. The obstacle to annealing of GaAs cells was their susceptibility to thermal damage at the temperatures required to completely anneal the radiation damage. GaAs cells with high temperature contacts and encapsulation were developed. The cells tested are designed for concentrator use at 30 suns AMO. The circular active area is 2.5 mm in diameter for an area of 0.05 sq cm. Typical one sun AMO efficiency of these cells is over 18 percent. The cells were demonstrated to be resistant to damage after thermal excursions in excess of 600 C. This high temperature tolerance should allow these cells to survive the annealing of radiation damage. A limited set of experiments were devised to investigate the feasibility of annealing these high temperature cells. The effect of repeated cycles of electron and proton irradiation was tested. The damage mechanisms were analyzed. Limitations in annealing recovery suggested improvements in cell design for more complete recovery. These preliminary experiments also indicate the need for further study to isolate damage mechanisms. The primary objective of the experiments was to demonstrate and quantify the annealing behavior of high temperature GaAs cells. Secondary objectives were to measure the radiation degradation and to determine the effect of repeated irradiation and anneal cycles.

  8. Low resistivity W{sub x}V{sub 1−x}O{sub 2}-based multilayer structure with high temperature coefficient of resistance for microbolometer applications

    Energy Technology Data Exchange (ETDEWEB)

    Émond, Nicolas; Hendaoui, Ali; Chaker, Mohamed, E-mail: chaker@emt.inrs.ca [INRS-Énergie, Matériaux et Télécommunications, 1650 Boulevard Lionel Boulet, Varennes, Québec J3X 1S2 (Canada)

    2015-10-05

    Materials that exhibit semiconductor-to-metal phase transition (SMT) are commonly used as sensing layers for the fabrication of uncooled microbolometers. The development of highly responsive microbolometers would benefit from using a sensing material that possesses a large thermal coefficient of resistance (TCR) close to room temperature and a resistivity low enough to compromise between noise reduction and high TCR, while it should also satisfies the requirements of current CMOS technology. Moreover, a TCR that remains constant when the IR camera surrounding temperature varies would contribute to achieve reliable temperature measurements without additional corrections steps for TCR temperature dependence. In this paper, the characteristics of the SMT occurring in undoped and tungsten-doped vanadium dioxide thin films deposited on LaAlO{sub 3} (100) substrates are investigated. They are further exploited to fabricate a W{sub x}V{sub 1−x}O{sub 2} (0 ≤ x ≤ 2.5) multilayer structure exhibiting a bottom-up gradient of tungsten content. This MLS displays a combination of properties that is promising for application to uncooled microbolometer, such as a large TCR of −10.4%/ °C and low resistivity values ranging from 0.012 to 0.10 Ω-cm over the temperature range 22 °C–42 °C.

  9. Near-zero temperature coefficient of resistivity associated with magnetic ordering in antiperovskite Mn{sub 3+x}Ni{sub 1−x}N

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Sihao; Sun, Ying; Wang, Lei; Shi, Kewen; Hu, Pengwei; Wang, Cong, E-mail: congwang@buaa.edu.cn [Center for Condensed Matter and Materials Physics, Department of Physics, Beihang University, Beijing 100191 (China); Wu, Hui; Huang, Qingzhen [NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6102 (United States)

    2016-01-25

    The near-zero temperature coefficient of resistivity (NZ-TCR) behavior is reported in the antiperovskite compounds Mn{sub 3+x}Ni{sub 1−x}N (0 ≤ x ≤ 0.333). Our results indicate that the broad temperature range (above 275 K extending to above 220 K) of NZ-TCR is obtained by Mn doping at the Ni site. The short-range magnetic ordering is revealed by both neutron powder diffraction and inverse magnetic susceptibility. Further, we find a strong correlation between the anomalous resistivity change of Mn{sub 3+x}Ni{sub 1−x}N from the metal-like to the NZ-TCR behavior and the lack of the long-range magnetic ordering. The possible mechanism of NZ-TCR behavior is discussed using the spin-disorder scattering model.

  10. Near-zero temperature coefficient of resistivity associated with magnetic ordering in antiperovskite Mn3+xNi1−xN

    International Nuclear Information System (INIS)

    The near-zero temperature coefficient of resistivity (NZ-TCR) behavior is reported in the antiperovskite compounds Mn3+xNi1−xN (0 ≤ x ≤ 0.333). Our results indicate that the broad temperature range (above 275 K extending to above 220 K) of NZ-TCR is obtained by Mn doping at the Ni site. The short-range magnetic ordering is revealed by both neutron powder diffraction and inverse magnetic susceptibility. Further, we find a strong correlation between the anomalous resistivity change of Mn3+xNi1−xN from the metal-like to the NZ-TCR behavior and the lack of the long-range magnetic ordering. The possible mechanism of NZ-TCR behavior is discussed using the spin-disorder scattering model

  11. A study on the estimation method of internal stresses caused by the difference of thermal expansion coefficients between concrete and reinforcement at elevated temperatures

    International Nuclear Information System (INIS)

    When a reinforced concrete member is exposed to high temperature conditions over 100degC, tensile strain occurs in the concrete and compressive strain occurs in reinforcements due to a difference of thermal expansion coefficients between concrete and reinforcement. Its mechanism is the same as that of restrained stress caused by drying shrinkage of concrete; tensile stress occurs in the concrete because drying shrinkage strain is restrained by reinforcements, but there is a different point that the phenomenon at a high temperature condition includes the change of mechanical properties of concrete and reinforcement. In the study, the phenomenon is measured in the experiments and is clarified quantitatively. Moreover, the estimation method, which is derived from expanding the equation of average strain of reinforcement in the CEB Design Manual, is suggested and is verified by the comparison with the experimental results. (author)

  12. Innovative High Temperature Fuel Cell systems

    NARCIS (Netherlands)

    Au, Siu Fai

    2003-01-01

    The world's energy consumption is growing extremely rapidly. Fuel cell systems are of interest by researchers and industry as the more efficient alternative to conventional thermal systems for power generation. The principle of fuel cell conversion does not involve thermal combustion and hence in th

  13. Reduced Temperature Coefficient of Capacitance (TCC) of Embedded Capacitor Films (ECFs) for Organic Substrates using SrTiO3 and Multifunctional Epoxy

    Science.gov (United States)

    Lee, Sangyong; Paik, Kyung-Wook

    2010-08-01

    Epoxy/ceramic composites have attracted great interest as embedded capacitor materials, mainly due to the process compatibility of epoxy with printed circuit boards (PCBs). However, one of the potential problems of epoxy/ceramic composites is the temperature dependence of their dielectric properties. This study focuses mainly on reducing the temperature coefficient of capacitance (TCC) of epoxy/ceramic composites using multifunctional epoxy and SrTiO3 powder. The TCC of an epoxy/ceramic composite mainly depends on the properties of its epoxy and ceramic powder. Using multifunctional epoxy, the epoxy resin showed two glass-transition temperatures, resulting in a lower dimensional change after the first glass-transition temperature. Additionally, the TCC of epoxy/SrTiO3 ECFs can be decreased by increasing the SrTiO3 powder content. As a result, reduced TCC of epoxy/ceramic composite capacitors using a multifunctional epoxy and SrTiO3 powder was successfully demonstrated for embedded capacitors in organic substrates.

  14. A new evaluation of the Creole experiment. Qualification of the PWR reactivity temperature coefficient using JEFF3.1.1 nuclear data library

    International Nuclear Information System (INIS)

    The CREOLE experimental program was conceived to supply accurate differential information on the Reactivity Temperature Coefficient (RTC) of standard UOX (clean and Boron poisoned) and MOX fuel type lattices in the whole temperature range of interest in a large PWR (from room temperature up to 300 deg C). This experiment has been recently reassessed using the most recent kinetic parameters of the library JEFF3.1.1. We have analyzed this newly assessed experimental data using the deterministic transport APOLLO2 code and the Monte Carlo transport code TRIPOLI4 with JEFF3.1.1 nuclear data library. The results show a remarkable agreement between the deterministic and Monte Carlo methods. The discrepancies between calculations and experiment on the RTC for clean and Boron poisoned UO2 PWR lattices is slightly negative, less than 1 pcm/ deg C which corresponds to the current target accuracy in LWR design calculations. Concerning the MOX lattices, the discrepancy between calculation and experiment on the average RTC for the temperature range from 20 deg C to 300 deg C is clearly positive, about +2 pcm/ deg C. (authors)

  15. Transport Coefficients of Fluids

    CERN Document Server

    Eu, Byung Chan

    2006-01-01

    Until recently the formal statistical mechanical approach offered no practicable method for computing the transport coefficients of liquids, and so most practitioners had to resort to empirical fitting formulas. This has now changed, as demonstrated in this innovative monograph. The author presents and applies new methods based on statistical mechanics for calculating the transport coefficients of simple and complex liquids over wide ranges of density and temperature. These molecular theories enable the transport coefficients to be calculated in terms of equilibrium thermodynamic properties, and the results are shown to account satisfactorily for experimental observations, including even the non-Newtonian behavior of fluids far from equilibrium.

  16. Analysis of Fuel Temperature Reactivity Coefficients According to Burn-up and Pu-239 Production in CANDU Reactor

    International Nuclear Information System (INIS)

    The resonances for some kinds of nuclides such as U-238 and Pu-239 are not easy to be accurately processed. In addition, the Pu-239 productions from burnup are also significant in CANDU, where the natural uranium is used as a fuel. In this study, the FTCs were analyzed from the viewpoints of the resonance self-shielding methodology and Pu-239 build-up. The lattice burnup calculations were performed using the TRITON module in the SCALE6 code system, and the BONAMI module was executed to obtain self-shielded cross sections using the Bondarenko approach. Two libraries, ENDF/B-VI.8 and ENDF/B-VII.0, were used to compare the Pu-239 effect on FTC, since the ENDF/B-VII has updated the Pu-239 cross section data. The FTCs of the CANDU reactor were newly analyzed using the TRITON module in the SCALE6 code system, and the BONAMI module was executed to apply the Bondarenko approach for self-shielded cross sections. When compared with some reactor physics codes resulting in slightly positive FTC in the specific region, the FTCs evaluated in this study showed a clear negativity over the entire fuel temperature range on fresh/equilibrium fuel. In addition, the FTCs at 960.15 K were slightly negative during the entire burnup. The effects on FTCs from the library difference between ENDF/B-VI.8 and ENDF/B-VII.0 are recognized to not be large; however, they appear more positive when more Pu-239 productions with burnup are considered. This feasibility study needs an additional benchmark evaluation for FTC calculations, but it can be used as a reference for a new FTC analysis in CANDU reactors

  17. High temperature polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    and motivated extensive research activity in the field. The last 11 chapters summarize the state-of-the-art of technological development of high temperature-PEMFCs based on acid doped PBI membranes including catalysts, electrodes, MEAs, bipolar plates, modelling, stacking, diagnostics and applications....

  18. Weibull strength variations between room temperature and high temperature Ni-3YSZ half-cells

    DEFF Research Database (Denmark)

    Curran, Declan; Frandsen, Henrik Lund; Hendriksen, Peter Vang

    2013-01-01

    800°C in a reducing atmosphere. The strength of an as sintered half-cell was also measured at room temperature for comparison. Weibull analysis was performed on large sample sets of 30 for statistical viability. The Weibull strength and elastic modulus of the room temperature tested reduced samples...... show a decrease of approximately 33% and 51% respectively, when compared to the oxidized samples tested at room temperature. When tested at elevated temperatures both Weibull strength and elastic modulus decrease further when compared to the room temperature reduced samples. However these further...... efficiency, increased degradation and/or the complete termination of a functioning stack. This paper investigates the effects of temperature on the mechanical strength of 3% yttria-stabilised zirconia half-cells. Strength was measured using a four-point bend method at room temperature and at 600°C, 700°C and...

  19. Real-time Monitoring of Internal Temperature and Voltage of High-temperature Fuel Cell Stack

    International Nuclear Information System (INIS)

    The nonuniform local temperature and voltage in the chemical reaction process of high-temperature proton exchange membrane fuel cell (HT-PEMFC) stack can affect the reaction of membrane electrode assembly (MEA) and the performance and life of fuel cell stack. The effectiveness and internal information of fuel cell stack can be discussed by using external measurement, invasive, theoretical modeling, and single temperature, or voltage measurement. But there are some problems, such as mm scale sensor, inaccurate measurement, influencing the fuel cell stack performance, and failing to know internal actual reactive state instantly. This study uses micro-electro-mechanical systems (MEMS) technology to develop a new generation flexible micro temperature and voltage sensors applicable to high-temperature electrochemical environment. Micro sensors have embedded in the cathode channel plate of HT-PEMFC stack. At the operating temperature of 170 °C and constant current (2, 10, 20 A), the curvilinear trends of local temperature and voltage inside the fuel cell stack measured by flexible micro sensors are consistent, proving the reliability of micro sensors. The test result also shows that the heat distribution in the fuel cell stack is nonuniform

  20. Design of high temperature irradiation materials inspection cells. (Spent fuel inspection cells) in the High Temperature Engineering Test Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Ino, Hiroichi; Ueta, Shouhei; Suzuki, Hiroshi; Sawa, Kazuhiro [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment; Tobita, Tsutomu [Nuclear Engineering Company, Ltd., Tokai, Ibaraki (Japan)

    2002-01-01

    This report summarizes design requirements and design results for shields, ventilation system and fuel handling devices for the high temperature irradiation materials inspection cells (spent fuel inspection cells). These cells are small cells to carry out few post-irradiation examinations of spent fuels, specimen, etc., which are irradiated in the High Temperature Engineering Test Reactor, since the cells should be built in limited space in the HTTR reactor building, the cells are designed considering relationship between the cells and the reactor building to utilize the limited space effectively. The cells consist of three partitioned hot cells with wall for neutron and gamma-ray shields, ventilation system including filtering units and fuel handling devices. The post-irradiation examinations of the fuels and materials are planed by using the cells and the Hot Laboratory of the Japan Materials Testing Reactor to establish the technology basis on high temperature gas-cooled reactors (HTGRs). In future, irradiation tests and post-irradiation examinations will be carried out with the cells to upgrade present HTGR technologies and to make the innovative basic research on high-temperature engineering. (author)

  1. Design of high temperature irradiation materials inspection cells. (Spent fuel inspection cells) in the High Temperature Engineering Test Reactor

    International Nuclear Information System (INIS)

    This report summarizes design requirements and design results for shields, ventilation system and fuel handling devices for the high temperature irradiation materials inspection cells (spent fuel inspection cells). These cells are small cells to carry out few post-irradiation examinations of spent fuels, specimen, etc., which are irradiated in the High Temperature Engineering Test Reactor, since the cells should be built in limited space in the HTTR reactor building, the cells are designed considering relationship between the cells and the reactor building to utilize the limited space effectively. The cells consist of three partitioned hot cells with wall for neutron and gamma-ray shields, ventilation system including filtering units and fuel handling devices. The post-irradiation examinations of the fuels and materials are planed by using the cells and the Hot Laboratory of the Japan Materials Testing Reactor to establish the technology basis on high temperature gas-cooled reactors (HTGRs). In future, irradiation tests and post-irradiation examinations will be carried out with the cells to upgrade present HTGR technologies and to make the innovative basic research on high-temperature engineering. (author)

  2. Materials for Intermediate-Temperature Solid-Oxide Fuel Cells

    Science.gov (United States)

    Kilner, John A.; Burriel, Mónica

    2014-07-01

    Solid-oxide fuel cells are devices for the efficient conversion of chemical energy to electrical energy and heat. Research efforts are currently addressed toward the optimization of cells operating at temperatures in the region of 600°C, known as intermediate-temperature solid-oxide fuel cells, for which materials requirements are very stringent. In addition to the requirements of mechanical and chemical compatibility, the materials must show a high degree of oxide ion mobility and electrochemical activity at this low temperature. Here we mainly examine the criteria for the development of two key components of intermediate-temperature solid-oxide fuel cells: the electrolyte and the cathode. We limit the discussion to novel approaches to materials optimization and focus on the fluorite oxide for electrolytes, principally those based on ceria and zirconia, and on perovskites and perovskite-related families in the case of cathodes.

  3. InGaN High Temperature Photovoltaic Cells Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this Phase I project is to demonstrate InGaN materials are appropriate for high operating temperature single junction solar cells. Single junction...

  4. InGaN High Temperature Photovoltaic Cells Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objectives of this Phase II project are to develop InGaN photovoltaic cells for high temperature and/or high radiation environments to TRL 4 and to define the...

  5. Novel High Temperature Membrane for PEM Fuel Cells Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation proposed in this STTR program is a high temperature membrane to increase the efficiency and power density of PEM fuel cells. The NASA application is...

  6. Temperature dependence of thermal expansion coefficient of (CuInTe{sub 2}){sub 1-x}(2ZnTe){sub x} solid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Bodnar, I.V.; Chibusova, L.V. [Belarus State Univ. of Information Science and Radio Electronics, Minsk (Belarus); Korzun, B.V. [Inst. of Physics of Solids and Semiconductors, Minsk (Belarus)

    2000-06-16

    Investigations have been made for the first time of the thermal expansion of the (CuInTe{sub 2}){sub 1-x}(2ZnTe){sub x} solid solutions. It has been demonstrated that the thermal expansion coefficient {alpha}{sub L} grows considerably in the temperature range from 77 to 300 K whereas the temperature dependence above 300 K is rather weak. For the solid solutions with 0=} 0.4). The Debye temperatures {theta}{sub D} and the average quadratic dynamic displacements u{sup 2} were calculated. (orig.)

  7. Experimental measurements of low temperature rate coefficients for neutral-neutral reactions of interest for atmospheric chemistry of Titan, Pluto and Triton: reactions of the CN radical.

    Science.gov (United States)

    Morales, Sébastien B; Le Picard, Sébastien D; Canosa, André; Sims, Ian R

    2010-01-01

    The kinetics of the reactions of cyano radical, CN (X2sigma+) with three hydrocarbons, propane (CH3CH2CH3), propene (CH3CH=CH2) and 1-butyne (CH[triple band]CCH2CH3) have been studied over the temperature range of 23-298 K using a CRESU (Cinétique de Réaction en Ecoulement Supersonique Uniforme or Reaction Kinetics in Uniform Supersonic Flow) apparatus combined with the pulsed laser photolysis-laser induced fluorescence technique. These reactions are of interest for the cold atmospheres of Titan, Pluto and Triton, as they might participate in the formation of nitrogen and carbon bearing molecules, including nitriles, that are thought to play an important role in the formation of hazes and biological molecules. All three reactions are rapid with rate coefficients in excess of 10(-10) cm3 molecule(-1) s(-1) at the lowest temperatures of this study and show behaviour characteristic of barrierless reactions. Temperature dependences, different for each reaction, are compared to those used in the most recent photochemical models of Titan's atmosphere. PMID:21302546

  8. Effects of heat treatment temperature on crystallization and thermal expansion coefficient of Li2 O-Al2 O3-SiO2

    Institute of Scientific and Technical Information of China (English)

    卢安贤; 贾明; 刘树江

    2004-01-01

    The basic glass of Li2 O-Al2 O3-SiO2 system using P2O5 as nucleator was prepared by means of conventional melt quenching technology, and the heat-treatment process was determined by using differential thermal analysis. The crystalline phases and the microstructure of the glass-ceramics were investigated by using X-ray diffraction and scanning electron microscopy. The results show that the glass based on Li2 O-Al2 O3-SiO2 oxides using P2 O5 as nucleator can be prepared at lower melt temperature of 1 450 ℃ and the glass-ceramics with lower thermal expansion coefficient of 21.6 × 10-7 ℃ 1 can also be obtained at 750 ℃. The glass-ceramics contain a few crystal phases in which the main crystal phase is β-quartz solid solution and the second crystal phase is β-spodumene solid solution. When the heat treatment temperature is not higher than 650 ℃, the transparent glass-ceramics containing β-quartzsolid solution can be prepared. β-quartz solid solution changes into β-spodumene solid solution at about 750 ℃. And the appearance of the glass-ceramics changes from translucent, part opaque to complete opaque with increasing temperature.

  9. Quantum fluctuations of mesoscopic biological cell at finite temperature

    Institute of Scientific and Technical Information of China (English)

    LI Hong-qi; XU Xing-lei

    2005-01-01

    On the basis of the quantization of mesoscopic biological cell equivalent circuit,we studied the quantum fluctuations of voltage and current of mesoscopic biological cell equivalent circuit as finite temperature by Bogoliuov transformation.The result shows that the quantum fluctuations of voltage and current not only relate with the parameters of equivalent circuit,temperature,but also decay with time.This result may have significant value on the design and application of the bio-electronic apparatus.

  10. A novel interferometric dilatometer in the 4–300 K temperature range: thermal expansion coefficient of SRM-731 borosilicate glass and stainless steel-304

    International Nuclear Information System (INIS)

    We present a newly designed heterodyne interferometric dilatometer for the measurement of the coefficient of thermal expansion of solids in the 4–300 K temperature range. The instrument can measure non-monotonic thermal expansion curves and has an accuracy better than 200 nm across the whole 4–300 K measurement range. The compensation for the misalignment of the interferometer design and the configuration of the sample holder make the instrument suitable to carry out measurements on any kind of sample that can be produced in a bar or rod shape. The measurement of a standard SRM-731 borosilicate glass and an SS-304 sample are presented and compared with literature data. (paper)

  11. A comparative study of 1/f noise and temperature coefficient of resistance in multiwall and single-wall carbon nanotube bolometers.

    Science.gov (United States)

    Lu, Rongtao; Kamal, Rayyan; Wu, Judy Z

    2011-07-01

    The 1/f noise and temperature coefficient of resistance (TCR) are investigated in multiwall carbon nanotube (MWCNT) film bolometers since both affect the bolometer detectivity directly. A comparison is made between the MWCNT film bolometers and their single-wall carbon nanotube (SWCNT) counterparts. The intrinsic noise level in the former has been found at least two orders of magnitude lower than that in the latter, which outweighs the moderately lower TCR absolute values in the former and results in higher bolometer detectivity in MWCNT bolometers. Interestingly, reduced noise and enhanced TCR can be obtained by improving the inter-tube coupling using thermal annealing in both SWCNT and MWCNT films, suggesting much higher detectivity may be achieved via engineering the inter-tube coupling. PMID:21576772

  12. Electrode Kinetics in High Temperature Fuel Cells

    DEFF Research Database (Denmark)

    Bay, Lasse

    1998-01-01

    ^3s and 10^5s for a cathodic current. For the deactivation is the time constant about 10^4s. The origin for the hysteresis is not clear, but expansion of the three phase boundary (TPB) or change of the catalytic properties due to surface segregation are suggested.The hysteresis phenomenon is also......-electrolyte interface show dynamics of the YSZ surface and formation of a bank of YSZ along the TPB. These changes are induced by passage of current. The origin of the dynamics behaviour may be a localised temperature increase or it might be driven by segregation. The dynamics of the YSZ surface seems to be...

  13. Development of a noise-based method for the determination of the moderator temperature coefficient of reactivity (MTC) in pressurized water reactors (PWRs)

    International Nuclear Information System (INIS)

    The Moderator Temperature Coefficient of reactivity (MTC) is an important safety parameter of Pressurized Water Reactors (PWRs). In most countries, the so-called at-power MTC has to be measured a few months before the reactor outage, in order to determine if the MTC will not become too negative. Usually, the at-power MTC is determined by inducing a change in the moderator temperature, which has to be compensated for by other means, such as a change in the boron concentration. An MTC measurement using the boron dilution method is analysed in this thesis. It is demonstrated that the uncertainty of such a measurement technique is so large, that the measured MTC could become more negative than what the Technical Specifications allow. Furthermore, this technique incurs a disturbance of the plant operation. For this reason, another technique relying on noise analysis was proposed a few years ago. In this technique, the MTC is inferred from the neutron noise measured inside the core and the moderator temperature noise measured at the core-exit, in the same or in a neighbouring fuel assembly. This technique does not require any perturbation of the reactor operation, but was nevertheless proven to underestimate the MTC by a factor of 2 to 5. In this thesis, it is shown, both theoretically and experimentally, that the reason of the MTC underestimation by noise analysis is the radially loosely coupled character of the moderator temperature noise throughout the core. A new MTC noise estimator, accounting for this radially non-homogeneous moderator temperature noise is proposed and demonstrated to give the correct MTC value. This new MTC noise estimator relies on the neutron noise measured in a single point of the reactor and the radially averaged moderator temperature noise measured inside the core. In the case of the Ringhals-2 PWR in Sweden, Gamma-Thermometers (GTs) offer such a possibility since in dynamic mode they measure the moderator temperature noise, whereas in static

  14. Temperature-dependent imaging of living cells by AFM

    International Nuclear Information System (INIS)

    Characterization of lateral organization of plasma membranes is a prerequisite to the understanding of membrane structure-function relationships in living cells. Lipid-lipid and lipid-protein interactions are responsible for the existence of various membrane microdomains involved in cell signalization and in numerous pathologies. Developing approaches for characterizing microdomains associate identification tools like recognition imaging with high-resolution topographical imaging. Membrane properties are markedly dependent on temperature. However, mesoscopic scale topographical information of cell surface in a temperature range covering most of cell biology experimentation is still lacking. In this work we have examined the possibility of imaging the temperature-dependent behavior of eukaryotic cells by atomic force microscopy (AFM). Our results establish that the surface of living CV1 kidney cells can be imaged by AFM, between 5 and 37 deg. C, both in contact and tapping modes. These first temperature-dependent data show that large cell structures appeared essentially stable at a microscopic scale. On the other hand, as shown by contact mode AFM, the surface was highly dynamic at a mesoscopic scale, with marked changes in apparent topography, friction, and deflection signals. When keeping the scanning conditions constant, a progressive loss in the image contrast was however observed, using tapping mode, on decreasing the temperature

  15. Solar cell junction temperature measurement of PV module

    KAUST Repository

    Huang, B.J.

    2011-02-01

    The present study develops a simple non-destructive method to measure the solar cell junction temperature of PV module. The PV module was put in the environmental chamber with precise temperature control to keep the solar PV module as well as the cell junction in thermal equilibrium with the chamber. The open-circuit voltage of PV module Voc is then measured using a short pulse of solar irradiation provided by a solar simulator. Repeating the measurements at different environment temperature (40-80°C) and solar irradiation S (200-1000W/m2), the correlation between the open-circuit voltage Voc, the junction temperature Tj, and solar irradiation S is derived.The fundamental correlation of the PV module is utilized for on-site monitoring of solar cell junction temperature using the measured Voc and S at a short time instant with open circuit. The junction temperature Tj is then determined using the measured S and Voc through the fundamental correlation. The outdoor test results show that the junction temperature measured using the present method, Tjo, is more accurate. The maximum error using the average surface temperature Tave as the junction temperature is 4.8 °C underestimation; while the maximum error using the present method is 1.3 °C underestimation. © 2010 Elsevier Ltd.

  16. Cone Penetrometer Load Cell Temperature and Radiation Testing Results

    Energy Technology Data Exchange (ETDEWEB)

    Follett, Jordan R.

    2013-08-28

    This report summarizes testing activities performed at the Pacific Northwest National Laboratory to verify the cone penetrometer load cell can withstand the tank conditions present in 241-AN-101 and 241-AN-106. The tests demonstrated the load cell device will operate under the elevated temperature and radiation levels expected to be encountered during tank farm deployment of the device.

  17. Microstructure and temperature coefficient of resistance of thin cermet resistor films deposited from CrSi2-Cr-SiC targets by S-gun magnetron

    International Nuclear Information System (INIS)

    Technological solutions for producing nanoscale cermet resistor films with sheet resistances above 1000 Ω/□ and low temperature coefficients of resistance (TCR) have been investigated. 2-40 nm thick cermet films were sputter deposited from CrSi2-Cr-SiC targets by a dual cathode dc S-gun magnetron. In addition to studying film resistance versus temperature, the nanofilm structural features and composition were analyzed using scanning electron microscopy, atomic force microscopy, high-resolution transmission electron microscopy, energy-dispersive x-ray spectroscopy, and electron energy loss spectroscopy. This study has revealed that all cermet resistor films deposited at ambient and elevated temperatures were amorphous. The atomic ratio of Si to Cr in these films was about 2 to 1. The film TCR displayed a significant increase when the deposited film thickness was reduced below 2.5 nm. An optimized sputter process consisting of wafer degassing, cermet film deposition at elevated temperature with rf substrate bias, and a double annealing in vacuum, consisting of in situ annealing following the film sputtering and an additional annealing following the exposure of the wafers to air, has been found to be very effective for the film thermal stabilization and for fine tuning the film TCR. Cermet films with thicknesses in the range of 2.5-4 nm deposited using this technique had sheet resistances ranging from 1800 to 1200 Ω/□ and TCR values from -50 ppm/ deg. C to near zero, respectively. A possible mechanism responsible for the high efficiency of annealing the cermet films in vacuum (after preliminary exposure to air), resulting in resistance stabilization and TCR reduction, is also discussed.

  18. Correlation between apparent diffusion coefficient value and pathological grading in pT1b clear cell renal cell carcinoma

    International Nuclear Information System (INIS)

    Objective: To evaluate the correlation of ADC values on 3.0 T MR with the pathological grades in pT1b clear cell renal cell carcinoma (CCRCC). Methods: Conventional MR images, ADC values and Fuhrman pathological grading of pT1b CCRCC were performed in 30 patients. Grade Ⅰ and Ⅱ were defined as low-grade group; grade Ⅲ and Ⅳ were defined as high-grade group. The differences of ADC values among four different pathologic grades were compared with a one-way analysis of variance. The comparison of ADC values of two different grade groups was performed with t test, and the ROC curve was performed to evaluate the diagnostic efficacy of ADC value. Correlation between pathological grading and ADC values was assessed with Spearman rank correlation analysis. Results: (1) The mean ADC value of grading Ⅰ (10 patients), Ⅱ (8 patients), Ⅲ (7 patients), Ⅳ (5 patients) was (0.94 ± 0.11) ×10-3 mm2/s, (0.82 ±0.13) × 10-3 mm2/s,(0.68 ±0.09) × 10-3 mm2/s, (0.59 ±0.03) × 10-3 mm2/s, respectively. Significant differences of ADC values among the four grades were present (F=16.422, P=0.000). (2) The mean ADC value of the low-grade group was significantly higher than that of the high-grade group (t=5.738, P=0.000). Sensitivity and specificity of diagnosing the low-grade group was 88.9% and 83.3% respectively. There was a negative correlation between pathological grading and ADC value (r=-0.807, P<0.05). Conclusions: The ADC values of pT1b CCRCC have close correlation with pathological grading. They can be used to predict the degree of tumor malignancy preoperatively and guide surgical planning. (authors)

  19. 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

    In this article an analytical method to calculate the dew point temperatures of the anode and cathode exit gas streams of a proton exchange membrane fuel cell is developed. The results of these calculations are used to create diagrams that show the dew point temperatures as function 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...

  20. Preliminary Low Temperature Electron Irradiation of Triple Junction Solar Cells

    Science.gov (United States)

    Stella, Paul M.; Mueller, Robert L.; Scrivner, Roy L.; Helizon, Roger S.

    2007-01-01

    For many years extending solar power missions far from the sun has been a challenge not only due to the rapid falloff in solar intensity (intensity varies as inverse square of solar distance) but also because some of the solar cells in an array may exhibit a LILT (low intensity low temperature) degradation that reduces array performance. Recent LILT tests performed on commercial triple junction solar cells have shown that high performance can be obtained at solar distances as great as approx. 5 AU1. As a result, their use for missions going far from the sun has become very attractive. One additional question that remains is whether the radiation damage experienced by solar cells under low temperature conditions will be more severe than when measured during room temperature radiation tests where thermal annealing may take place. This is especially pertinent to missions such as the New Frontiers mission Juno, which will experience cell irradiation from the trapped electron environment at Jupiter. Recent testing2 has shown that low temperature proton irradiation (10 MeV) produces cell degradation results similar to room temperature irradiations and that thermal annealing does not play a factor. Although it is suggestive to propose the same would be observed for low temperature electron irradiations, this has not been verified. JPL has routinely performed radiation testing on commercial solar cells and has also performed LILT testing to characterize cell performance under far sun operating conditions. This research activity was intended to combine the features of both capabilities to investigate the possibility of any room temperature annealing that might influence the measured radiation damage. Although it was not possible to maintain the test cells at a constant low temperature between irradiation and electrical measurements, it was possible to obtain measurements with the cell temperature kept well below room temperature. A fluence of 1E15 1MeV electrons was

  1. Intersubband optical absorption coefficients and refractive index changes in a graded quantum well under intense laser field: Effects of hydrostatic pressure, temperature and electric field

    Energy Technology Data Exchange (ETDEWEB)

    Ungan, F., E-mail: fungan@cumhuriyet.edu.tr [Department of Physics, Cumhuriyet University, 58140 Sivas (Turkey); Grupo de Materia Condensade-UdeA, Instituto de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Restrepo, R.L. [Grupo de Materia Condensade-UdeA, Instituto de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Escuela de Ingeniería de Antioquia AA 7516, Medellín (Colombia); Mora-Ramos, M.E. [Grupo de Materia Condensade-UdeA, Instituto de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Ave. Universidad 1001, CP 62209, Cuernavaca, Morelos (Mexico); Morales, A.L.; Duque, C.A. [Grupo de Materia Condensade-UdeA, Instituto de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia)

    2014-02-01

    The effects of hydrostatic pressure, temperature, and electric field on the optical absorption coefficients and refractive index changes associated with intersubband transition in a typical GaAs/Ga{sub 0.7}Al{sub 0.3}As graded quantum well under intense laser field have been investigated theoretically. The electron energy eigenvalues and the corresponding eigenfunctions of the graded quantum well are calculated within the effective mass approximation and envelope wave function approach. The analytical expressions of the optical properties are obtained using the compact density-matrix approach and the iterative method. The numerical results show that the linear and nonlinear optical properties depend strongly on the intense laser field and electric field but weakly on the hydrostatic pressure and temperature. Additionally, it has been found that the electronic and optical properties in a GaAs/Ga{sub 0.7}Al{sub 0.3}As graded quantum well under the intense laser field can be tuned by changing these external inputs. Thus, these results give a new degree of freedom in the devices applications.

  2. Intersubband optical absorption coefficients and refractive index changes in a graded quantum well under intense laser field: Effects of hydrostatic pressure, temperature and electric field

    International Nuclear Information System (INIS)

    The effects of hydrostatic pressure, temperature, and electric field on the optical absorption coefficients and refractive index changes associated with intersubband transition in a typical GaAs/Ga0.7Al0.3As graded quantum well under intense laser field have been investigated theoretically. The electron energy eigenvalues and the corresponding eigenfunctions of the graded quantum well are calculated within the effective mass approximation and envelope wave function approach. The analytical expressions of the optical properties are obtained using the compact density-matrix approach and the iterative method. The numerical results show that the linear and nonlinear optical properties depend strongly on the intense laser field and electric field but weakly on the hydrostatic pressure and temperature. Additionally, it has been found that the electronic and optical properties in a GaAs/Ga0.7Al0.3As graded quantum well under the intense laser field can be tuned by changing these external inputs. Thus, these results give a new degree of freedom in the devices applications

  3. Operating Cell Temperature Determination in Flat-Plate Photovoltaic Modules

    International Nuclear Information System (INIS)

    Two procedures (simplified and complete) to determine me 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 me dependence of this temperature on several environmental (sky, ground and ambient temperatures, solar irradiance, wind speed, etc.) and structural (module geometry and size, encapsulating materials, anti reflexive 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) 27 refs

  4. Comparison of Fuel Temperature Coefficients of PWR UO{sub 2} Fuel from Monte Carlo Codes (MCNP6.1 and KENO6)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyung-O; Roh, Gyuhong; Lee, Byungchul [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    As a result, there was a difference within about 300-400 pcm between keff values at each enrichment due to the difference of codes and nuclear data used in the evaluations. The FTC was changed to be less negative with the increase of uranium enrichment, and it followed the form of asymptotic curve. However, it is necessary to perform additional study for investigating what factor causes the differences more than two standard deviation (2σ) among the FTCs at partial enrichment region. The interaction probability of incident neutron with nuclear fuel is depended on the relative velocity between the neutron and the target nuclei. The Fuel Temperature Coefficient (FTC) is defined as the change of Doppler effect with respect to the change in fuel temperature without any other change such as moderator temperature, moderator density, etc. In this study, the FTCs for UO{sub 2} fuel were evaluated by using MCNP6.1 and KENO6 codes based on a Monte Carlo method. In addition, the latest neutron cross-sections (ENDF/B-VI and VII) were applied to analyze the effect of these data on the evaluation of FTC, and nuclear data used in MCNP calculations were generated from the makxsf code. An evaluation of the Doppler effect and FTC for UO{sub 2} fuel widely used in PWR was conducted using MCNP6.1 and KENO6 codes. The ENDF/B-VI and VII were also applied to analyze what effect these data has on those evaluations. All cross-sections needed for MCNP calculation were produced using makxsf code. The calculation models used in the evaluations were based on the typical PWR UO{sub 2} lattice.

  5. Temperature dependent electroreflectance study of CdTe solar cells

    International Nuclear Information System (INIS)

    Cadmium telluride is a promising material for large scale photovoltaic applications. In this paper we study CdS/CdTe heterojunction solar cells with electroreflectance spectroscopy. Both CdS and CdTe layers in solar cells were grown sequentially without intermediate processing by the close-space sublimation method. Electroreflectance measurements were performed in the temperature range of T = 100–300 K. Two solar cells were investigated with conversion efficiencies of 4.1% and 9.6%. The main focus in this work was to study the temperature dependent behavior of the broadening parameter and the bandgap energy of CdTe thin film in solar cells. Room temperature bandgap values of CdTe were Eg = 1.499 eV and Eg = 1.481 eV for higher and lower efficiency solar cells, respectively. Measured bandgap energies are lower than for single crystal CdTe. The formation of CdTe1−xSx solid solution layer on the surface of CdTe is proposed as a possible cause of lower bandgap energies. - Highlights: ► Temperature dependent electroreflectance measurements of CdS/CdTe solar cells ► Investigation of junction properties between CdS and CdTe ► Formation of CdTe1− xSx solid solution layer in the junction area

  6. Temperature-Responsive Polymer Modified Surface for Cell Sheet Engineering

    Directory of Open Access Journals (Sweden)

    Teruo Okano

    2012-08-01

    Full Text Available In the past two decades, as a novel approach for tissue engineering, cell sheet engineering has been proposed by our laboratory. Poly(N-isopropylacrylamide (PIPAAm, which is a well-known temperature-responsive polymer, has been grafted on tissue culture polystyrene (TCPS surfaces through an electron beam irradiated polymerization. At 37 °C, where the PIPAAm modified surface is hydrophobic, cells can adhere, spread on the surface and grow to confluence. By decreasing temperature to 20 °C, since the surface turns to hydrophilic, cells can detach themselves from the surface spontaneously and form an intact cell sheet with extracellular matrix. For obtaining a temperature-induced cell attachment and detachment, it is necessary to immobilize an ultra thin PIPAAm layer on the TCPS surfaces. This review focuses on the characteristics of PIAPAm modified surfaces exhibiting these intelligent properties. In addition, PIPAAm modified surfaces giving a rapid cell-sheet recovery has been further developed on the basis of the characteristic of the PIPAAm surface. The designs of temperature-responsive polymer layer have provided an enormous potential to fabricate clinically applicable regenerative medicine.

  7. Changes in the chemical properties and swelling coefficient of alfalfa root cell walls in the presence of toluene as a toxic agent.

    Science.gov (United States)

    Sharifi, M; Khoshgoftarmanesh, A H; Hadadzadeh, H

    2016-04-01

    The influence of toluene pollution on the chemical properties and swelling coefficient of root cell walls in alfalfa (Medicago sativa L.) was investigated. Two sets of alfalfa seedlings were selected and one set was treated with 450 mg L(-1) toluene in the nutrient solution under hydroponic culture. Thirty days after treatment with toluene, alfalfa plants were harvested and the root cell walls were isolated. Fourier-transform infrared (FTIR) spectroscopy was carried out for the characterization of the root cell walls composition. The cation exchange capacity (CEC) and the swelling coefficient of the root cell walls (Kcw) were estimated at various pH values. The toluene contamination significantly reduced the mass of the cell wall material in the alfalfa roots. According to the FTIR spectra, the toluene pollution can change the alfalfa root cell wall properties by reducing the cell wall functional groups. These functional groups are probably related to the proteins and polysaccharides in the cell wall. Also, toluene pollution strongly reduced CEC and Kcw of the root cell walls. The results show that the decrease in the active sites of adsorption on the root cell walls as a response to toluene pollution can affect the water flow rate and the mineral nutrients uptake by roots. PMID:26728292

  8. Initial Experience of 3-Tesla Apparent Diffusion Coefficient Values in Characterizing Squamous Cell Carcinomas of the Head and Neck

    International Nuclear Information System (INIS)

    Background: With the increased clinical use of 3-Tesla (3T) magnets, it becomes important to identify the potential applications of advanced magnetic resonance (MR) imaging techniques such as diffusion-weighted imaging in head and neck pathologies. Purpose: To establish the 3T apparent diffusion coefficient (ADC) values for normal neck structures, and to examine the utility of ADC values in distinguishing head and neck squamous cell carcinomas (HNSCC) from normal neck anatomy. Material and Methods: 3T diffusion-weighted imaging was performed on 10 normal volunteers and 10 patients with known HNSCC. In the volunteers, mean ADC was calculated in the parotid gland, submandibular gland, base of the tongue, pterygoid muscle, masseter muscle, paraspinal muscles, true vocal cord, thyroid gland, thyroid cartilage, cricoid cartilage, and lymph nodes. The mean tumor ADC value was calculated from the 10 patients with HNSCC and compared with the normal ADC values from various neck structures. Results: The mean ADC value measured in the HNSCC was 1.101 (±0.214)x10-3mm2/s. This was significantly lower than ADC values of paraspinal muscles, pterygoid muscle, masseter muscle, thyroid gland, and base of the tongue (P=0.0006, 0.0002, 0.0001, 0.001, and 0.002, respectively). The tumor ADC values were not significantly different from ADC values of parotid and submandibular glands (P=0.057 and 0.14, respectively). Conclusion: 3T ADC values show potential for distinguishing HNSCC from normal extracranial head and neck structures

  9. CREOLE experiment study on the reactivity temperature coefficient with sensitivity and uncertainty analysis using the MCNP5 code and different neutron cross section evaluations

    Energy Technology Data Exchange (ETDEWEB)

    Boulaich, Y., E-mail: boulaich@cnesten.org.ma [Radiations and Nuclear Systems Laboratory, University Abdelmalek Essaadi, Faculty of Sciences of Tetouan (Morocco); CEN-Maamora, CNESTEN, Rabat (Morocco); El Bardouni, T. [Radiations and Nuclear Systems Laboratory, University Abdelmalek Essaadi, Faculty of Sciences of Tetouan (Morocco); Erradi, L. [University Mohammed V of Rabat (Morocco); Chakir, E. [LRM/EPTN, Department of Physics, Faculty of Sciences, Kenitra (Morocco); Boukhal, H. [Radiations and Nuclear Systems Laboratory, University Abdelmalek Essaadi, Faculty of Sciences of Tetouan (Morocco); Nacir, B. [CEN-Maamora, CNESTEN, Rabat (Morocco); El Younoussi, C.; El Bakkari, B. [Radiations and Nuclear Systems Laboratory, University Abdelmalek Essaadi, Faculty of Sciences of Tetouan (Morocco); CEN-Maamora, CNESTEN, Rabat (Morocco); Merroun, O.; Zoubair, M. [Radiations and Nuclear Systems Laboratory, University Abdelmalek Essaadi, Faculty of Sciences of Tetouan (Morocco)

    2011-08-15

    Highlights: > In the present work, we have analyzed the CREOLE experiment on the reactivity temperature coefficient (RTC) by using the three-dimensional continuous energy code (MCNP5) and the last updated nuclear data evaluations. > Calculation-experiment discrepancies of the RTC were analyzed and the results have shown that the JENDL3.3 and JEFF3.1 evaluations give the most consistent values. > In order to specify the source of the relatively large discrepancy in the case of ENDF-BVII nuclear data evaluation, the k{sub eff} discrepancy between ENDF-BVII and JENDL3.3 was decomposed by using sensitivity and uncertainty analysis technique. - Abstract: In the present work, we analyze the CREOLE experiment on the reactivity temperature coefficient (RTC) by using the three-dimensional continuous energy code (MCNP5) and the last updated nuclear data evaluations. This experiment performed in the EOLE critical facility located at CEA/Cadarache, was mainly dedicated to the RTC studies for both UO{sub 2} and UO{sub 2}-PuO{sub 2} PWR type lattices covering the whole temperature range from 20 deg. C to 300 deg. C. We have developed an accurate 3D model of the EOLE reactor by using the MCNP5 Monte Carlo code which guarantees a high level of fidelity in the description of different configurations at various temperatures taking into account their consequence on neutron cross section data and all thermal expansion effects. In this case, the remaining error between calculation and experiment will be awarded mainly to uncertainties on nuclear data. Our own cross section library was constructed by using NJOY99.259 code with point-wise nuclear data based on ENDF-BVII, JEFF3.1 and JENDL3.3 evaluation files. The MCNP model was validated through the axial and radial fission rate measurements at room and hot temperatures. Calculation-experiment discrepancies of the RTC were analyzed and the results have shown that the JENDL3.3 and JEFF3.1 evaluations give the most consistent values; the

  10. Electrical transport and temperature coefficient of resistance in polycrystalline La0.7−xAgxCa0.3MnO3 pellets: Analysis in terms of a phase coexistence transport model and phase separation model

    International Nuclear Information System (INIS)

    The temperature dependent resistivity and temperature coefficient of resistance of Ag doped La0.7−xAgxCa0.3MnO3 polycrystalline pellets (x=0, 0.05, 0.10, 0.15, and 0.20) are investigated. Ag substitution enhances the conductivity of this system. The Curie temperature also increases from 260 to 283 K with increasing Ag content. Using phase-coexistence transport model and phase separation model, we calculated the resistivity as a function of temperature and the temperature coefficient of resistivity (TCR) behavior. Comparing the calculated maximum TCR, we found that it is related to activation energy, transition temperature, and disorder in doped manganites. The relationship between the proposed TCR behavior and the transport parameters can suggest conditions improving TCRmax of doped manganites for the use of the bolometric infrared detectors

  11. Evaluation of MHD materials for use in high-temperature fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Guidotti, R.

    1978-06-15

    The MHD and high-temperature fuel cell literature was surveyed for data pertaining to materials properties in order to identify materials used in MHD power generation which also might be suitable for component use in high-temperature fuel cells. Classes of MHD-electrode materials evaluated include carbides, nitrides, silicides, borides, composites, and oxides. Y/sub 2/O/sub 3/-stabilized ZrO/sub 2/ used as a reference point to evaluate materials for use in the solid-oxide fuel cell. Physical and chemical properties such as electrical resistivity, coefficient of thermal expansion, and thermodynamic stability toward oxidation were used to screen candidate materials. A number of the non-oxide ceramic MHD-electrode materials appear promising for use in the solid-electrolyte and molten-carbonate fuel cell as anodes or anode constituents. The MHD-insulator materials appear suitable candidates for electrolyte-support tiles in the molten-carbonate fuel cells. The merits and possible problem areas for these applications are discussed and additional needed areas of research are delineated.

  12. Direct dimethyl ether high temperature polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    Vassiliev, Anton; Jensen, Jens Oluf; Li, Qingfeng;

    A high temperature polybenzimidazole (PBI) polymer fuel cell was fed with dimethyl ether (DME) and water vapour mixture on the anode at ambient pressure with air as oxidant. A peak power density of 79 mW/cm2 was achieved at 200°C. A conventional polymer based direct DME fuel cell is liquid fed and...... suffers from low DME solubility in water. When the DME - water mixture is fed as vapour miscibility is no longer a problem. The increased temperature is more beneficial for the kinetics of the direct oxidation of DME than of methanol. The Open Circuit Voltage (OCV) with DME operation was 50 to 100 m...

  13. Low temperature electrolytes for lithium/silver vanadium oxide cells

    Science.gov (United States)

    Tuhovak, Denise R.; Takeuchi, Esther S.

    1991-01-01

    Combinations of methyl formate (MF) and propylene carbonate (PC) using salt concentrations of 0.6 to 2.4 M, with lithium hexafluoroarsenate and lithium tetrafluoroborate in a five to one molar ratio, were investigated as electrolytes in lithium/silver vanadium oxide batteries. The composition of the electrolyte affected cell performance at low temperature, self-discharge and abuse resistance as characterized by short circuit and crush testing. The electrolyte that provided the best combination of good low temperature performance, low cell self-discharge and abuse resistance was 0.6 M salt in 10:90 PC/MF.

  14. Status and prospects of intermediate temperature solid oxide fuel cells

    Institute of Scientific and Technical Information of China (English)

    Bangwu Liu; Yue Zhang

    2008-01-01

    Compared with conventional electric power generation systems, the solid oxide fuel cell (SOFC) has many advantages because of its unique features. High temperature SOFC has been successfully developed to its commercial applications, but it still faces many problems which hamper large-scale commercial applications of SOFC. To reduce the cost of SOFC, intermediate tem-perature solid oxide fuel cell (IT-SOFC) is presently under rapid development. The status of IT-SOFC was reviewed with emphasis on discussion of their component materials.

  15. 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.

  16. Condensation heat transfer coefficients of HCFC22, R410A, R407C and HFC134a at various temperatures on a plain horizontal tube

    International Nuclear Information System (INIS)

    In this study, external condensation heat transfer coefficients (HTCs) of HCFC22, R410A, R407C, and HFC134a were measured on a smooth horizontal tube at 30, 39, and 50 .deg. C with the wall subcooling of 3∼8 .deg. C. The results showed that condensation HTCs decreased for all fluids tested with an increase in temperature. This is due mainly to such properties as the saturated liquid density and liquid thermal conductivity. These properties decrease as the temperature increase and accordingly HTCs decrease. The condensation HTCs of R410A are 9.2∼19.7% higher than those of HCFC22 while those of R134a are 2.5∼10.2% lower than those of HCFC22. Condensation HTCs of R407C, non-azeotropic mixture, are 29.4?34.3% lower than those of HCFC22. Overall, the HTCs of R407C are much lower than those of HCFC22, HFC134a and R410A due to the mass transfer resistance in a diffusion vapor film. Condensation HTCs of HCFC22 and HFC134a are higher than those calculated by Nusselt's equation by 7.7∼11.8% and 4.0∼11.1% respectively. On the other hand, HTCs of R407C measured on plain tube, however, are not well predicted by these well-known prediction correlations due to the introduction of mass transfer resistance associated with non-azeotropic mixtures

  17. Chromium–niobium co-doped vanadium dioxide films: Large temperature coefficient of resistance and practically no thermal hysteresis of the metal–insulator transition

    Directory of Open Access Journals (Sweden)

    Kenichi Miyazaki

    2016-05-01

    Full Text Available We investigated the effects of chromium (Cr and niobium (Nb co-doping on the temperature coefficient of resistance (TCR and the thermal hysteresis of the metal–insulator transition of vanadium dioxide (VO2 films. We determined the TCR and thermal-hysteresis-width diagram of the V1−x−yCrxNbyO2 films by electrical-transport measurements and we found that the doping conditions x ≳ y and x + y ≥ 0.1 are appropriate for simultaneously realizing a large TCR value and an absence of thermal hysteresis in the films. By using these findings, we developed a V0.90Cr0.06Nb0.04O2 film grown on a TiO2-buffered SiO2/Si substrate that showed practically no thermal hysteresis while retaining a large TCR of 11.9%/K. This study has potential applications in the development of VO2-based uncooled bolometers.

  18. Chromium-niobium co-doped vanadium dioxide films: Large temperature coefficient of resistance and practically no thermal hysteresis of the metal-insulator transition

    Science.gov (United States)

    Miyazaki, Kenichi; Shibuya, Keisuke; Suzuki, Megumi; Sakai, Kenichi; Fujita, Jun-ichi; Sawa, Akihito

    2016-05-01

    We investigated the effects of chromium (Cr) and niobium (Nb) co-doping on the temperature coefficient of resistance (TCR) and the thermal hysteresis of the metal-insulator transition of vanadium dioxide (VO2) films. We determined the TCR and thermal-hysteresis-width diagram of the V1-x-yCrxNbyO2 films by electrical-transport measurements and we found that the doping conditions x ≳ y and x + y ≥ 0.1 are appropriate for simultaneously realizing a large TCR value and an absence of thermal hysteresis in the films. By using these findings, we developed a V0.90Cr0.06Nb0.04O2 film grown on a TiO2-buffered SiO2/Si substrate that showed practically no thermal hysteresis while retaining a large TCR of 11.9%/K. This study has potential applications in the development of VO2-based uncooled bolometers.

  19. A full-dimensional model of ozone forming reaction: the absolute value of the recombination rate coefficient, its pressure and temperature dependencies.

    Science.gov (United States)

    Teplukhin, Alexander; Babikov, Dmitri

    2016-07-28

    Rigorous calculations of scattering resonances in ozone are carried out for a broad range of rotational excitations. The accurate potential energy surface of Dawes is adopted, and a new efficient method for calculations of ro-vibrational energies, wave functions and resonance lifetimes is employed (which uses hyper-spherical coordinates, the sequential diagonalization/truncation approach, grid optimization and complex absorbing potential). A detailed analysis is carried out to characterize distributions of resonance energies and lifetimes, their rotational/vibrational content and their positions with respect to the centrifugal barrier. Emphasis is on the contribution of these resonances to the recombination process that forms ozone. It is found that major contributions come from localized resonances at energies near the top of the barrier. Delocalized resonances at higher energies should also be taken into account, while very narrow resonances at low energies (trapped far behind the centrifugal barrier) should be treated as bound states. The absolute value of the recombination rate coefficient, its pressure and temperature dependencies are obtained using the energy-transfer model developed in the earlier work. Good agreement with experimental data is obtained if one follows the suggestion of Troe, who argued that the energy transfer mechanism of recombination is responsible only for 55% of the recombination rate (with the remaining 45% coming from the competing chaperon mechanism). PMID:27364351

  20. A computer model for a high temperature fuel cell

    OpenAIRE

    E. Hernández-Pacheco; Mann, M D

    2006-01-01

    A computer model is developed for determining the performance characteristics (e.g., current-voltage curves) of a solid oxide fuel cell. The model determines the fuel/oxidant concentration, the temperature profiles and the current density along the fuel and oxidant channels, respectively. Then, the average of the local current density distribution is used to determine the current-voltage curves (IV curves) over the entire range of cell potential, i.e., from open circuit voltage to short circu...

  1. New polymer electrolytes for low temperature fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Sundholm, F.; Elomaa, M.; Ennari, J.; Hietala, S.; Paronen, M. [Univ. of Helsinki (Finland). Lab. of Polymer Chemistry

    1998-12-31

    Proton conducting polymer membranes for demanding applications, such as low temperature fuel cells, have been synthesised and characterised. Pre-irradiation methods are used to introduce sulfonic acid groups, directly or using polystyrene grafting, in stable, preformed polymer films. The membranes produced in this work show promise for the development of cost-effective, highly conducting membranes. (orig.)

  2. Lowering the temperature of solid oxide fuel cells.

    Science.gov (United States)

    Wachsman, Eric D; Lee, Kang Taek

    2011-11-18

    Fuel cells are uniquely capable of overcoming combustion efficiency limitations (e.g., the Carnot cycle). However, the linking of fuel cells (an energy conversion device) and hydrogen (an energy carrier) has emphasized investment in proton-exchange membrane fuel cells as part of a larger hydrogen economy and thus relegated fuel cells to a future technology. In contrast, solid oxide fuel cells are capable of operating on conventional fuels (as well as hydrogen) today. The main issue for solid oxide fuel cells is high operating temperature (about 800°C) and the resulting materials and cost limitations and operating complexities (e.g., thermal cycling). Recent solid oxide fuel cells results have demonstrated extremely high power densities of about 2 watts per square centimeter at 650°C along with flexible fueling, thus enabling higher efficiency within the current fuel infrastructure. Newly developed, high-conductivity electrolytes and nanostructured electrode designs provide a path for further performance improvement at much lower temperatures, down to ~350°C, thus providing opportunity to transform the way we convert and store energy. PMID:22096189

  3. Note: A variable temperature cell for spectroscopy of thin films

    Science.gov (United States)

    Brock-Nannestad, T.; Nielsen, C. B.; Bak, H. Ø.; Pittelkow, M.

    2013-04-01

    We report the design and construction of a cell that enables precisely controlled measurement of UV/Vis spectra of thin films on transparent substrates at temperatures up to 800 K. The dimensions of the setup are accommodated by a standard Varian Cary 5E spectrophotometer allowing for widespread use in standard laboratory settings. The cell also fits in a Bio-Rad IR-spectrometer. The cell is constructed with an outer water cooled heat shield of aluminum and an inner sample holder with heating element, thermo-resistor and windows, made from nickel coated copper. The cell can operate both in air, and with an inert gas filling. We illustrate the utility of the cell by characterization of three commercially available near infrared absorbers that are commonly used for laser welding of plastics and are known to possess high thermal stability.

  4. Advanced anodes for high-temperature fuel cells

    DEFF Research Database (Denmark)

    Atkinson, A.; Barnett, S.; Gorte, R.J.;

    2004-01-01

    Fuel cells will undoubtedly find widespread use in this new millennium in the conversion of chemical to electrical energy, as they offer very high efficiencies and have unique scalability in electricity-generation applications. The solid-oxide fuel cell (SOFC) is one of the most exciting of these...... energy technologies; it is an all-ceramic device that operates at temperatures in the range 500-1,000degreesC. The SOFC offers certain advantages over lower temperature fuel cells, notably its ability to use carbon monoxide as a fuel rather than being poisoned by it, and the availability of high......-grade exhaust heat for combined heat and power, or combined cycle gas-turbine applications. Although cost is clearly the most important barrier to widespread SOFC implementation, perhaps the most important technical barriers currently being addressed relate to the electrodes, particularly the fuel electrode or...

  5. Optimization of Storage Temperature for Cultured ARPE-19 Cells

    Directory of Open Access Journals (Sweden)

    Lara Pasovic

    2013-01-01

    Full Text Available Purpose. The establishment of future retinal pigment epithelium (RPE replacement therapy is partly dependent on the availability of tissue-engineered RPE cells, which may be enhanced by the development of suitable storage methods for RPE. This study investigates the effect of different storage temperatures on the viability, morphology, and phenotype of cultured RPE. Methods. ARPE-19 cells were cultured under standard conditions and stored in HEPES-buffered MEM at nine temperatures (4°C, 8°C, 12°C, 16°C, 20°C, 24°C, 28°C, 32°C, and 37°C for seven days. Viability and phenotype were assessed by a microplate fluorometer and epifluorescence microscopy, while morphology was analyzed by scanning electron microscopy. Results. The percentage of viable cells preserved after storage was highest in the 16°C group (48.7%±9.8%; P<0.01 compared to 4°C, 8°C, and 24°C–37°C; P<0.05 compared to 12°C. Ultrastructure was best preserved at 12°C, 16°C, and 20°C. Expression of actin, ZO-1, PCNA, caspase-3, and RPE65 was maintained after storage at 16°C compared to control cells that were not stored. Conclusion. Out of nine temperatures tested between 4°C and 37°C, storage at 12°C, 16°C, and 20°C was optimal for maintenance of RPE cell viability, morphology, and phenotype. The preservation of RPE cells is critically dependent on storage temperature.

  6. Comparison of inter-diffusion coefficients for Ni/Cu thin films determined from classical heating analysis and linear temperature ramping analysis by means of profile reconstruction and a numerical solution of Fick's law

    International Nuclear Information System (INIS)

    Classical inter-diffusion studies assume a constant time of annealing when samples are annealed in a furnace. It is assumed that the sample temperature reaches the annealing temperature immediately after insertion, while the sample temperature immediately drops to room temperature after removal, the annealing time being taken as the time between insertion and removal. Using the above assumption, the diffusion coefficient can be calculated in a number of ways. In reality, the sample temperature does not immediately reach the annealing temperature; instead it rises at a rate governed by several heat transfer mechanisms, depending on the annealing procedure. For short annealing times, the sample temperature may not attain the annealing temperature, while for extended annealing times the sample temperature may reach the annealing temperature only for a fraction of the annealing time. To eliminate the effect of heat transfer mechanisms, a linear temperature ramping regime is proposed. Used in conjunction with a suitable profile reconstructing technique and a numerical solution of Fick's second law, the inter-diffusion parameters obtained from a linear ramping of Ni/Cu thin film samples can be compared to those obtained from calculations performed with the so-called Mixing-Roughness-Information model or any other suitable method used to determine classical diffusion coefficients.

  7. Comparison of inter-diffusion coefficients for Ni/Cu thin films determined from classical heating analysis and linear temperature ramping analysis by means of profile reconstruction and a numerical solution of Fick's law

    Energy Technology Data Exchange (ETDEWEB)

    Joubert, H.D. [Department of Physics, University of the Free State, P.O. Box 339, ZA-9300 Bloemfontein (South Africa); Terblans, J.J. [Department of Physics, University of the Free State, P.O. Box 339, ZA-9300 Bloemfontein (South Africa)], E-mail: TerblansJJ.sci@ufs.ac.za; Swart, H.C. [Department of Physics, University of the Free State, P.O. Box 339, ZA-9300 Bloemfontein (South Africa)

    2009-08-15

    Classical inter-diffusion studies assume a constant time of annealing when samples are annealed in a furnace. It is assumed that the sample temperature reaches the annealing temperature immediately after insertion, while the sample temperature immediately drops to room temperature after removal, the annealing time being taken as the time between insertion and removal. Using the above assumption, the diffusion coefficient can be calculated in a number of ways. In reality, the sample temperature does not immediately reach the annealing temperature; instead it rises at a rate governed by several heat transfer mechanisms, depending on the annealing procedure. For short annealing times, the sample temperature may not attain the annealing temperature, while for extended annealing times the sample temperature may reach the annealing temperature only for a fraction of the annealing time. To eliminate the effect of heat transfer mechanisms, a linear temperature ramping regime is proposed. Used in conjunction with a suitable profile reconstructing technique and a numerical solution of Fick's second law, the inter-diffusion parameters obtained from a linear ramping of Ni/Cu thin film samples can be compared to those obtained from calculations performed with the so-called Mixing-Roughness-Information model or any other suitable method used to determine classical diffusion coefficients.

  8. Low Temperature Plasma Kills SCaBER Cancer Cells

    Science.gov (United States)

    Barekzi, Nazir; van Way, Lucas; Laroussi, Mounir

    2013-09-01

    Squamous cell carcinoma of the bladder is a rare type of bladder cancer that forms as a result of chronic irritation of the epithelial lining of the bladder. The cell line used in this study is SCaBER (ATCC® HTB-3™) derived from squamous cell carcinoma of the human urinary bladder. Current treatments of bladder cancer include surgery, radiation and chemotherapy. However, the cost of these treatments, the potential toxicity of the chemotherapeutic agents and the systemic side-effects warrant an alternative to current cancer treatment. This paper represents preliminary studies to determine the effects of biologically tolerant plasma (BTP) on a cell line of human bladder cancer cells. Previous work by our group using the plasma pencil revealed the efficacy of BTP on leukemia cells suspended in solution. Based on these earlier findings we hypothesized that the plasma exposure would elicit a similar programmed cell death in the SCaBER cells. Trypan blue exclusion and MTT assays revealed the cell killing after exposure to BTP. Our study indicates that low temperature plasma generated by ionizing helium gas and the reactive species may be a suitable and safe alternative for cancer therapy.

  9. Computational Seebeck Coefficient Measurement Simulations

    OpenAIRE

    Martin, Joshua

    2012-01-01

    We have employed finite element analysis to develop computational Seebeck coefficient metrology simulations. This approach enables a unique exploration of multiple probe arrangements and measurement techniques within the same temporal domain. To demonstrate the usefulness of this approach, we have performed these Seebeck coefficient measurement simulations to quantitatively explore perturbations to voltage and temperature correspondence, by comparing simultaneous and staggered data acquisitio...

  10. Permeability and Diffusion Coefficients of Single Methyl Lactate Enantiomers in Nafion® and Cellophane Membranes Measured in Diffusion Cell.

    Czech Academy of Sciences Publication Activity Database

    Hovorka, Š.; Randová, A.; Borbášová, T.; Sysel, P.; Vychodilová, Hana; Červenková Šťastná, Lucie; Brožová, Libuše; Žitka, Jan; Storch, Jan; Kačírková, Marie; Drašar, P.; Izák, Pavel

    2016-01-01

    Roč. 158, JAN 28 (2016), s. 322-332. ISSN 1383-5866 R&D Projects: GA ČR(CZ) GAP106/12/0569 Institutional support: RVO:67985858 ; RVO:61389013 Keywords : diffusion coefficient measurement * permeability * nafion * cellophane * chirality of polymer membrane Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.091, year: 2014

  11. File list: His.Adl.20.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Adl.20.AllAg.Temperature_sensitive_cells dm3 Histone Adult Temperature sensitiv...barchive.biosciencedbc.jp/kyushu-u/dm3/assembled/His.Adl.20.AllAg.Temperature_sensitive_cells.bed ...

  12. File list: His.Adl.05.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Adl.05.AllAg.Temperature_sensitive_cells dm3 Histone Adult Temperature sensitiv...barchive.biosciencedbc.jp/kyushu-u/dm3/assembled/His.Adl.05.AllAg.Temperature_sensitive_cells.bed ...

  13. File list: His.Adl.50.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Adl.50.AllAg.Temperature_sensitive_cells dm3 Histone Adult Temperature sensitiv...barchive.biosciencedbc.jp/kyushu-u/dm3/assembled/His.Adl.50.AllAg.Temperature_sensitive_cells.bed ...

  14. File list: His.Adl.10.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available His.Adl.10.AllAg.Temperature_sensitive_cells dm3 Histone Adult Temperature sensitiv...barchive.biosciencedbc.jp/kyushu-u/dm3/assembled/His.Adl.10.AllAg.Temperature_sensitive_cells.bed ...

  15. Effect of elevated temperatures on cell cycle kinetics of rat gliosarcoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Ross-Riveros, P.

    1978-07-01

    9L rat gliosarcoma cells were examined in vitro for survival response to hyperthermic temperatures ranging from 39.0/sup 0/ to 45.0/sup 0/C for graded exposure times. At 43.0/sup 0/C, the split exposure response was also studied. Changes in cell cycle kinetics resulting from hyperthermia were compared for isosurvival levels achieved by appropriate exposure time to either 42.5/sup 0/C or 43.0/sup 0/C. After heat treatment, cells were held at 37.0/sup 0/C for varying recovery periods. Cells were then either prepared for flow microfluorometry (FMF), or exposed to tritiated thymidine (/sup 3/HTdR) for autoradiography. The survival studies indicated that the rate of change in cell killing for each increasing degree centigrade was greater for temperatures below 43.0/sup 0/C than for temperatures above 43.0/sup 0/C. The shoulder width of the survival curves was maximal at 42.5/sup 0/C. The shoulder width represents an important parameter since it describes a threshold time after which significant cell killing occurs. Thus both 43.0/sup 0/C, the temperature at which mortality kinetics changed, and 42.5/sup 0/C, the temperature at which the shoulder width was maximum, represent critical temperatures for the 9L cells. When 9L cells were given an initial conditioning exposure to 43.0/sup 0/C, then returned to 37/sup 0/C for 3 hrs, followed by graded exposure intervals at 43.0/sup 0/, the resulting survival curve indicated that cells required longer times for equal cell killing than for the single exposure condition, suggesting that the cells possess a capability to adapt to the higher temperature.

  16. 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.

  17. High-Temperature Oxidation-Resistant and Low Coefficient of Thermal Expansion NiAl-Base Bond Coat Developed for a Turbine Blade Application

    Science.gov (United States)

    2003-01-01

    Many critical gas turbine engine components are currently made from Ni-base superalloys that are coated with a thermal barrier coating (TBC). The TBC consists of a ZrO2-based top coat and a bond coat that is used to enhance the bonding between the superalloy substrate and the top coat. MCrAlY alloys (CoCrAlY and NiCrAlY) are currently used as bond coats and are chosen for their very good oxidation resistance. TBC life is frequently limited by the oxidation resistance of the bond coat, along with a thermal expansion mismatch between the metallic bond coat and the ceramic top coat. The aim of this investigation at the NASA Glenn Research Center was to develop a new longer life, higher temperature bond coat by improving both the oxidation resistance and the thermal expansion characteristics of the bond coat. Nickel aluminide (NiAl) has excellent high-temperature oxidation resistance and can sustain a protective Al2O3 scale to longer times and higher temperatures in comparison to MCrAlY alloys. Cryomilling of NiAl results in aluminum nitride (AlN) formation that reduces the coefficient of thermal expansion (CTE) of the alloy and enhances creep strength. Thus, additions of cryomilled NiAl-AlN to CoCrAlY were examined as a potential bond coat. In this work, the composite alloy was investigated as a stand-alone substrate to demonstrate its feasibility prior to actual use as a coating. About 85 percent of prealloyed NiAl and 15 percent of standard commercial CoCrAlY alloys were mixed and cryomilled in an attritor with stainless steel balls used as grinding media. The milling was carried out in the presence of liquid nitrogen. The milled powder was consolidated by hot extrusion or by hot isostatic pressing. From the consolidated material, oxidation coupons, four-point bend, CTE, and tensile specimens were machined. The CTE measurements were made between room temperature and 1000 C in an argon atmosphere. It is shown that the CTE of the NiAl-AlN-CoCrAlY composite bond coat

  18. Cell asymmetry correction for temperature modulated differential scanning calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Ishikiriyama, K.; Wunderlich, B. [Tennessee Univ., Knoxville, TN (United States). Dept. of Chemistry]|[Oak Ridge National Lab., TN (United States)

    1996-12-31

    The quality of measurement of heat capacity by differential scanning calorimetry (DSC) is based on strict symmetry of the twin calorimeter, which is important for temperature-modulated DSC. Heat capacities for sapphire-filled and empty aluminium calorimeters (pans) under designed cell imbalance caused by different pan-masses were measured. In addition, positive and negative signs of asymmetry were explored by analyzing the phase-shift between temperature and heat flow for sapphire and empty runs. The phase shifts change by more than 18{degree} depending on asymmetry sign. Once the asymmetry sign is determined, the asymmetry correction for modulated DSC can be made.

  19. Quantification of in situ temperature measurements on a PBI-based high temperature PEMFC unit cell

    DEFF Research Database (Denmark)

    Lebæk, Jesper; Ali, Syed Talat; Møller, Per;

    2010-01-01

    sensors showed minimal influence on cell performance, this difference seen in performance is believed to be caused by different bipolar plate materials. The measurement method is suitable for obtaining detailed data for validation of computational models, moreover the results indicate that the method can...... anode and cathode flow plates. The purpose of this study is to investigate the feasibility of the proposed temperature characterization method and to identify the temperature distribution on an operating HT-PEM in various modes of operation, including a 700 h sensors durability test. The embedded...

  20. Evaluation of the three-phase equilibrium method for measuring temperature dependence of internally consistent partition coefficients (K OW, K OA, and K AW) for volatile methylsiloxanes and trimethylsilanol

    OpenAIRE

    Xu, Shihe; Kropscott, Bruce

    2014-01-01

    Partitioning equilibria and their temperature dependence of chemicals between different environmental media are important in determining the fate, transport, and distribution of contaminants. Unfortunately, internally consistent air/water (K AW), 1-octanol/air (K OA), and 1-octanol/water (K OW) partition coefficients, as well as information on their temperature dependence, are scarce for organosilicon compounds because of the reactivity of these compounds in water and octanol and their extrem...

  1. Polybenzimidazoles based on high temperature polymer electrolyte fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Linares Leon, Jose Joaquin; Camargo, Ana Paula M.; Ashino, Natalia M.; Morgado, Daniella L.; Frollini, Elisabeth; Paganin, Valdecir A.; Gonzalez, Ernesto Rafael [Universidade de Sao Paulo (IQSC/USP), Sao Carlos, SP (Brazil); Bajo, Justo Lobato [University of Castilla-La Mancha, Ciudad Real (Spain). Dept. of Chemical Engineering

    2010-07-01

    This work presents an interesting approach in order to enhance the performance of Polymer Electrolyte Membrane Fuel Cells (PEMFC) by means of an increase in the operational temperature. For this, two polymeric materials, Poly(2,5-bibenzimidazole) (ABPBI) and Poly[2,2'-(m-phenyl en)-5,5' bib enzimidazol] (PBI), impregnated with phosphoric acid have been utilized. These have shown excellent properties, such as thermal stability above 500 deg C, reasonably high conductivity when impregnated with H{sub 3}PO{sub 4} and a low permeability to alcohols compared to Nafion. Preliminary fuel cells measurements on hydrogen based Polymer Electrolyte Membrane Fuel Cell (PEMFC) displayed an interestingly reasonable good fuel cell performance, a quite reduced loss when the hydrogen stream was polluted with carbon monoxide, and finally, when the system was tested with an ethanol/water (E/W) fuel, it displayed quite promising results that allows placing this system as an attractive option in order to increase the cell performance and deal with the typical limitations of low temperature Nafion-based PEMFC. (author)

  2. High Temperature Polymers for use in Fuel Cells

    Science.gov (United States)

    Peplowski, Katherine M.

    2004-01-01

    NASA Glenn Research Center (GRC) is currently working on polymers for fuel cell and lithium battery applications. The desire for more efficient, higher power density, and a lower environmental impact power sources has led to interest in proton exchanges membrane fuels cells (PEMFC) and lithium batteries. A PEMFC has many advantages as a power source. The fuel cell uses oxygen and hydrogen as reactants. The resulting products are electricity, heat, and water. The PEMFC consists of electrodes with a catalyst, and an electrolyte. The electrolyte is an ion-conducting polymer that transports protons from the anode to the cathode. Typically, a PEMFC is operated at a temperature of about 80 C. There is intense interest in developing a fuel cell membrane that can operate at higher temperatures in the range of 80 C- 120 C. Operating the he1 cell at higher temperatures increases the kinetics of the fuel cell reaction as well as decreasing the susceptibility of the catalyst to be poisoned by impurities. Currently, Nafion made by Dupont is the most widely used polymer membrane in PEMFC. Nafion does not function well above 80 C due to a significant decrease in the conductivity of the membrane from a loss of hydration. In addition to the loss of conductivity at high temperatures, the long term stability and relatively high cost of Nafion have stimulated many researches to find a substitute for Nafion. Lithium ion batteries are popular for use in portable electronic devices, such as laptop computers and mobile phones. The high power density of lithium batteries makes them ideal for the high power demand of today s advanced electronics. NASA is developing a solid polymer electrolyte that can be used for lithium batteries. Solid polymer electrolytes have many advantages over the current gel or liquid based systems that are used currently. Among these advantages are the potential for increased power density and design flexibility. Automobiles, computers, and cell phones require

  3. High Temperature PEM Fuel Cells and Organic Fuels

    DEFF Research Database (Denmark)

    Vassiliev, Anton

    harvested from the cells. This is completely avoided at the elevated temperatures with the additional benefit of increased kinetics. In the presented work an experimental setup for testing direct dimethyl ether high temperature fuel cells is described, proposing a novel design of an evaporator for a burst...... the experiments have been conducted at atmospheric pressure. Experiments with varying amounts of PBI in the cathode catalyst layer has shown that there is a minimum content limit for the preparation of a well dispersed catalyst ink of 15 carbon to PBI weight ratio in the currently used ink formulation......Modern way of life demands enormous amounts of energy, which so far has been mainly produced by combustion of various types of fossil fuel. Increased amounts of atmospheric CO2 and global warming leading to severe climate changes are the consequence. There is a need to make the energy production...

  4. High Temperature PEM Fuel Cell Systems, Control and Diagnostics

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen; Justesen, Kristian Kjær; Sahlin, Simon Lennart

    fuels utilizes one of the main advantages of the high temperature PEM fuel cell: robustness to fuel quality and impurities. In order for such systems to provide efficient, robust, and reliable energy, proper control strategies are needed. The complexity and nonlinearity of many of the components in such......Various system topologies are available when it comes to designing high temperature PEM fuel cell systems. Very simple system designs are possible using pure hydrogen, and more complex system designs present themselves when alternative fuels are desired, using reformer systems. The use of reformed...... systems allow the development of both simple linear and also advanced fuzzy logic and neural network controllers able to adapt system performance to the ever changing conditions which the systems operate in over their entire lifetime....

  5. High temperature PEM fuel cell. Final report. Public part

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, Jens Oluf (DTU (DK)); Yde Andersen, S.; Rycke, T. de (IRD Fuel Cells A/S (DK)); Nilsson, M. (Danish Power Systems ApS (DK)); Christensen, Torkild, (DONG Energy (DK))

    2006-07-01

    The main outcome of the project is the development of stacking technology for high temperature PEMFC stacks based on phosphoric acid doped polybenzimidazole membranes (PBI-membranes) and a study of the potential of a possible accommodation of HT-PEMFC in the national energy system. Stacks of different lengths (up to 40 cells) have been built using two different approaches in terms of plate materials and sealing. The stacks still need maturing and further testing to prove satisfactory reliability, and a steady reduction of production cost is also desired (as in general for fuel cells). However, during the project the process has come a long way. The survey of HT-PEM fuel cells and their regulatory power in the utility system concludes that fuel cells will most likely not be the dominating technique for regulation, but as no other technique has that potential alone, fuel cells are well suited to play a role in the system provided that the establishment of a communication system is not too complicated. In order to maintain an efficient power system with high reliability in a distributed generation scenario, it is important that communication between TSO (Transmission System Operator) and fuel cells is included in the fuel cell system design at an early stage. (au)

  6. Feedback reactivity coefficients and their coupling

    International Nuclear Information System (INIS)

    Coupled reactivity feedback coefficients which accounts for variation in fuel temperature and moderator void simultaneously, have been determined for swimming pool type research reactor namely Pakistan Research Reactor PARR-1. The state of art is core criticality calculations, employing lattice cell code WIMS-D/4 and application of Taylor series expansion for core reactivity up to third order, involving two variables, i.e. fuel temperature and coolant void. The spectral effects in one region due to change of parameter in other region have also been studied. When spectral changes in moderator region due to 20 K change in fuel temperature have been incorporated in the calculation of fuel temperature coefficient, the results seems to be improved by 4.12%. Further, the results of void coefficient of reactivity show the improvement of 0.1% when the spectral effect in fuel region due to 5% change in void in moderator region is taken into account. These differences seem to be an improvement in the results, as physically any change in one region is accompanied by change in the other region

  7. Feedback reactivity coefficients and their coupling

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Rustam [Pakistan Institute of Engineering and Applied Sciences, P.O. Nilore, Islamabad (Pakistan)]. E-mail: rustamzia@yahoo.com; Hamid, Tehsin [Directorate of Safety, P.O. Box 1114, Islamabad (Pakistan); Bakhtyar, Sabiha [Pakistan Institute of Nuclear Science and Technology, P.O. Nilore, Islamabad (Pakistan)

    2007-05-15

    Coupled reactivity feedback coefficients which accounts for variation in fuel temperature and moderator void simultaneously, have been determined for swimming pool type research reactor namely Pakistan Research Reactor PARR-1. The state of art is core criticality calculations, employing lattice cell code WIMS-D/4 and application of Taylor series expansion for core reactivity up to third order, involving two variables, i.e. fuel temperature and coolant void. The spectral effects in one region due to change of parameter in other region have also been studied. When spectral changes in moderator region due to 20 K change in fuel temperature have been incorporated in the calculation of fuel temperature coefficient, the results seems to be improved by 4.12%. Further, the results of void coefficient of reactivity show the improvement of 0.1% when the spectral effect in fuel region due to 5% change in void in moderator region is taken into account. These differences seem to be an improvement in the results, as physically any change in one region is accompanied by change in the other region.

  8. Photo-Activated Low Temperature, Micro Fuel Cell Power Source

    Energy Technology Data Exchange (ETDEWEB)

    Harry L. Tuller

    2007-03-30

    A Key objective of this program is to identify electrodes that will make it possible to significantly reduce the operating temperature of micro-SOFC and thin film-based SOFCs. Towards this end, efforts are directed towards: (a) identifying the key rate limiting steps which limit presently utilized electrodes from performing at reduced temperatures, as well as, (b) investigating the use of optical, as opposed to thermal energy, as a means for photocatalyzing electrode reactions and enabling reduced operating temperatures. During Phase I, the following objectives were achieved: (a) assembly and testing of our unique Microprobe Thin Film Characterization System; (b) fabrication of the model cathode materials system in thin film form by both PLD and ink jet printing; and (c) the successful configuration and testing of the model materials as cathodes in electrochemical cells. A further key objective (d) to test the potential of illumination in enhancing electrode performance was also achieved.

  9. 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...

  10. Investigation the cause of plasma treatment for low temperature annealed dye-sensitized solar cells

    Science.gov (United States)

    Zen, Shungo; Komatsu, Yuta; Ono, Ryo

    2015-09-01

    Dye-sensitized solar cells (DSSCs) require annealing of TiO2photoelectrodes at 450 C to 550 C. However, such high-temperature annealing is unfavorable because it limits the use of materials that cannot withstand high temperatures, such as plastic substrates. In our previous paper, a low temperature annealing technique of TiO2 photoelectrodes using ultraviolet light and dielectric barrier discharge treatments was proposed to reduce the annealing temperature from 450 C to 150 C for a TiO2 paste containing an organic binder. Here, we investigated the cause of plasma treatment via the Nyquist diagram (Cole-Cole plot) of DSSCs. The Nyquist diagram was masured with a frequency response analyzer (NF Corporation, FRA5022) under 100 mW/cm2 illumination of a calibrated xenon lamp (Hamamatsu L2274, 150W). The lifetime of the electrons, the effective electron diffusion coefficient, and the electron diffusion length of TiO2 photoelectrodes were determined by analyzing the Nyquist diagrams. As a result of analyzing the Nyquist diagrams, it was shown that plasma treatment can reduce the electron transport resistance and promote the necking of Hot UV annealed TiO2 nanoparticles. This work was supported by Grant-in-Aid for JSPS Fellows.

  11. Development of thin film amorphous silicon oxide/microcrystalline silicon double-junction solar cells and their temperature dependence

    Energy Technology Data Exchange (ETDEWEB)

    Sriprapha, K.; Piromjit, C.; Limmanee, A.; Sritharathikhun, J. [Institute of Solar Energy Technology Development (SOLARTEC), National Science and Technology Development Agency (NSTDA), 111 Thailand Science Park, Phahonyothin Road, Klong 1, Klong Luang, Pathumthani 12120 (Thailand)

    2011-01-15

    We have developed thin film silicon double-junction solar cells by using micromorph structure. Wide bandgap hydrogenated amorphous silicon oxide (a-SiO:H) film was used as an absorber layer of top cell in order to obtain solar cells with high open circuit voltage (V{sub oc}), which are attractive for the use in high temperature environment. All p, i and n layers were deposited on transparent conductive oxide (TCO) coated glass substrate by a 60 MHz-very-high-frequency plasma enhanced chemical vapor deposition (VHF-PECVD) technique. The p-i-n-p-i-n double-junction solar cells were fabricated by varying the CO{sub 2} and H{sub 2} flow rate of i top layer in order to obtain the wide bandgap with good quality material, which deposited near the phase boundary between a-SiO:H and hydrogenated microcrystalline silicon oxide ({mu}c-SiO:H), where the high V{sub oc} can be expected. The typical a-SiO:H/{mu}c-Si:H solar cell showed the highest initial cell efficiency of 10.5%. The temperature coefficient (TC) of solar cells indicated that the values of TC for conversion efficiency ({eta}) of the double-junction solar cells were inversely proportional to the initial V{sub oc}, which corresponds to the bandgap of the top cells. The TC for {eta} of typical a-SiO:H/{mu}c-Si:H was -0.32%/ C, lower than the value of conventional a-Si:H/{mu}c-Si:H solar cell. Both the a-SiO:H/{mu}c-Si:H solar cell and the conventional solar cell showed the same light induced degradation ratio of about 20%. We concluded that the solar cells using wide bandgap a-SiO:H film in the top cells are promising for the use in high temperature regions. (author)

  12. Determination of infinite dilution activity coefficients using HS-SPME/GC/FID for hydrocarbons in furfural at temperatures of (298.15, 308.15, and 318.15) K

    International Nuclear Information System (INIS)

    Highlights: ► Two approaches were proposed using SPME on determination of infinite dilution activity coefficients. ► Infinite dilution activity coefficients of nine solutes in solvent furfural at T = (298.15, 308.15, and 318.15) K. ► Fiber–gas partition coefficients of nine solutes on PDMS at T = (298.15, 308.15, and 318.15) K. ► Optical microscopy analysis and statistical tests to measure possible damages on fiber coating. ► Advantages and limitations of methodology proposed were discussed. - Abstract: A new methodology using the headspace solid phase microextraction (HS-SPME) technique has been used to evaluate the infinite dilution activity coefficient (γ12∞) of nine hydrocarbons (alkanes, cycloalkanes, and aromatics) in furfural solvent. The main objective of this study was to validate a faster and lower cost methodology expanding the use of HS-SPME to determine infinite dilution activity of solutes in organic solvents. Two approaches were proposed for the determination of γ12∞ in order to use this technique (HS-SPME). In addition, the fiber–gas partition coefficients (Kfg) for each analyte at each of the studied temperatures were determined. The activity and partition coefficients have been reported at temperatures of (298.15, 308.15, and 318.15) K. The data were compared with the literature infinite dilution data determined by other methods such as liquid–gas chromatography (GLC) and gas stripping. Partial molar excess enthalpies of mixing at infinite dilution for each solute have been determined. The fibers were tested before and after each experiment, using statistical methods to ensure that their properties do not change during the experiments. The fibers were also analyzed by optical microscopy to evaluate possible surface damage by comparing them with new fibers. The activity coefficient values correlated well with the data in the literature and showed average deviations less than 10%.

  13. Investigation on the temperature-dependence of absorption properties of solar cells with micro-structured surfaces

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The temperature of a solar cell will increase when it is exposed to the sunlight,which results in variations of optical parameters and thermal expansion coefficient of the cell,thus affecting its spectral absorption feature.This paper is aimed to investigate the effects of temperature on the absorption property of solar cells with micro-structured surfaces.By taking hemispherical, cylindrical and spherical surfaces as models,numerical computation is conducted to obtain spectral distribution of absorptance of such surfaces with different structural parameters by means of the finite difference time domain(FDTD)method.Furthermore,the effects of material properties and structural period on the absorption property are also investigated.

  14. High pressure Moissanite-anvil cells for the low temperature Hall effect measurements of oxide superconductors

    Science.gov (United States)

    Yomo, Shusuke; Tozer, Stanley

    2013-03-01

    The Hall effect was successfully measured for a single crystal of high temperature superconductor in a Moissanite-anvil clamp cell up to 5 GPa, with proper arrangement of lead wires and a sample. Zylon gasket, good in electrical insulation, worked well up to 5 GPa. The 30-40 % increase of the clamped pressure was observed during cooling to below 60 K. The appreciable pressure effect of the a-b plane Hall coefficient was observed and negative for La2 - x Srx CuO4 with x = 0.090. The result is discussed with those for sintered samples and those studied with a different pressurizing method. Thanks are due to Visiting Scientist Program, NHMFL, and NNSA grant DE-FG52-03NA00066.

  15. Theoretical examination of effective oxygen diffusion coefficient and electrical conductivity of polymer electrolyte fuel cell porous components

    Science.gov (United States)

    Inoue, Gen; Yokoyama, Kouji; Ooyama, Junpei; Terao, Takeshi; Tokunaga, Tomomi; Kubo, Norio; Kawase, Motoaki

    2016-09-01

    The reduction of oxygen transfer resistance through porous components consisting of a gas diffusion layer (GDL), microporous layer (MPL), and catalyst layer (CL) is very important to reduce the cost and improve the performance of a PEFC system. This study involves a systematic examination of the relationship between the oxygen transfer resistance of the actual porous components and their three-dimensional structure by direct measurement with FIB-SEM and X-ray CT. Numerical simulations were carried out to model the properties of oxygen transport. Moreover, based on the model structure and theoretical equations, an approach to the design of new structures is proposed. In the case of the GDL, the binder was found to obstruct gas diffusion with a negative effect on performance. The relative diffusion coefficient of the MPL is almost equal to that of the model structure of particle packing. However, that of CL is an order of magnitude less than those of the other two components. Furthermore, an equation expressing the relative diffusion coefficient of each component can be obtained with the function of porosity. The electrical conductivity of MPL, which is lower than that of the carbon black packing, is considered to depend on the contact resistance.

  16. High temperature PEM fuel cells - Degradation and durability

    Energy Technology Data Exchange (ETDEWEB)

    Araya, S.S.

    2012-12-15

    This work analyses the degradation issues of a High Temperature Proton Exchange Membrane Fuel Cell (HT-PEMFC). It is based on the assumption that given the current challenges for storage and distribution of hydrogen, it is more practical to use liquid alcohols as energy carriers for fuel cells. Among these, methanol is very attractive, as it can be obtained from a variety of renewable sources and has a relatively low reforming temperature for the production of hydrogen rich gaseous mixture. The effects on HT-PEMFC of the different constituents of this gaseous mixture, known as a reformate gas, are investigated in the current work. For this, an experimental set up, in which all these constituents can be fed to the anode side of a fuel cell for testing, is put in place. It includes mass flow controllers for the gaseous species, and a vapor delivery system for the vapor mixture of the unconverted reforming reactants. Electrochemical Impedance Spectroscopy (EIS) is used to characterize the effects of these impurities. The effects of CO were tested up to 2% by volume along with other impurities. All the reformate impurities, including ethanol-water vapor mixture, cause loss in the performance of the fuel cell. In general, CO{sub 2} dilutes the reactants, if tested alone at high operating temperatures (180 C), but tends to exacerbate the effects of CO if they are tested together. On the other hand, CO and methanol-water vapor mixture degrade the fuel cell proportionally to the amounts in which they are tested. In this dissertation some of the mechanisms with which the impurities affect the fuel cell are discussed and interdependence among the effects is also studied. This showed that the combined effect of reformate impurities is more than the arithmetic sum of the individual effects of reformate constituents. The results of the thesis help to understand better the issues of degradation and durability in fuel cells, which can help to make them more durable and

  17. [Prediction of Encapsulation Temperatures of Copolymer Films in Photovoltaic Cells Using Hyperspectral Imaging Techniques and Chemometrics].

    Science.gov (United States)

    Lin, Ping; Chen, Yong-ming; Yao, Zhi-lei

    2015-11-01

    A novel method of combination of the chemometrics and the hyperspectral imaging techniques was presented to detect the temperatures of Ethylene-Vinyl Acetate copolymer (EVA) films in photovoltaic cells during the thermal encapsulation process. Four varieties of the EVA films which had been heated at the temperatures of 128, 132, 142 and 148 °C during the photovoltaic cells production process were used for investigation in this paper. These copolymer encapsulation films were firstly scanned by the hyperspectral imaging equipment (Spectral Imaging Ltd. Oulu, Finland). The scanning band range of hyperspectral equipemnt was set between 904.58 and 1700.01 nm. The hyperspectral dataset of copolymer films was randomly divided into two parts for the training and test purpose. Each type of the training set and test set contained 90 and 10 instances, respectively. The obtained hyperspectral images of EVA films were dealt with by using the ENVI (Exelis Visual Information Solutions, USA) software. The size of region of interest (ROI) of each obtained hyperspectral image of EVA film was set as 150 x 150 pixels. The average of reflectance hyper spectra of all the pixels in the ROI was used as the characteristic curve to represent the instance. There kinds of chemometrics methods including partial least squares regression (PLSR), multi-class support vector machine (SVM) and large margin nearest neighbor (LMNN) were used to correlate the characteristic hyper spectra with the encapsulation temperatures of of copolymer films. The plot of weighted regression coefficients illustrated that both bands of short- and long-wave near infrared hyperspectral data contributed to enhancing the prediction accuracy of the forecast model. Because the attained reflectance hyperspectral data of EVA materials displayed the strong nonlinearity, the prediction performance of linear modeling method of PLSR declined and the prediction precision only reached to 95%. The kernel-based forecast models were

  18. Electrolytes For Intermediate Temperature Solid Oxide Fuel Cells

    Directory of Open Access Journals (Sweden)

    Rękas M.

    2015-06-01

    Full Text Available Solid electrolytes for construction of the intermediate-temperature solid oxide fuel cells, IT-SOFC, have been reviewed. Yttrium stabilized tetragonal zirconia polycrystals, YTZP, as a potential electrolyte of IT-SOFC have been highlighted. The experimental results involving structural, microstructural, electrical properties based on our own studies were presented. In order to study aluminum diffusion in YTZP, aluminum oxide was deposited on the surface of 3 mol.% yttria stabilized tetragonal zirconia polycrystals (3Y-TZP. The samples were annealed at temperatures from 1523 to 1773 K. Diffusion profiles of Al in the form of mean concentration vs. depth in B-type kinetic region were investigated by secondary ion mass spectroscopy (SIMS. Both the lattice (DB and grain boundary (DGB diffusion were determined.

  19. Determination of octanol-air partition coefficients and supercooled liquid vapor pressures of PAHs as a function of temperature: Application to gas-particle partitioning in an urban atmosphere

    Science.gov (United States)

    Odabasi, Mustafa; Cetin, Eylem; Sofuoglu, Aysun

    Octanol-air partition coefficients ( KOA) for 14 polycyclic aromatic hydrocarbons (PAHs) were determined as a function of temperature using the gas chromatographic retention time method. log KOA values at 25° ranged over six orders of magnitude, between 6.34 (acenaphthylene) and 12.59 (dibenz[ a,h]anthracene). The determined KOA values were within factor of 0.7 (dibenz[ a,h]anthracene) to 15.1 (benz[ a]anthracene) of values calculated as the ratio of octanol-water partition coefficient to dimensionless Henry's law constant. Supercooled liquid vapor pressures ( PL) of 13 PAHs were also determined using the gas chromatographic retention time technique. Activity coefficients in octanol calculated using KOA and PL ranged between 3.2 and 6.2 indicating near-ideal solution behavior. Atmospheric concentrations measured in this study in Izmir, Turkey were used to investigate the partitioning of PAHs between particle and gas-phases. Experimental gas-particle partition coefficients ( Kp) were compared to the predictions of KOA absorption and KSA (soot-air partition coefficient) models. Octanol-based absorptive partitioning model predicted lower partition coefficients especially for relatively volatile PAHs. Ratios of measured/modeled partition coefficients ranged between 1.1 and 15.5 (4.5±6.0, average±SD) for KOA model. KSA model predictions were relatively better and measured to modeled ratios ranged between 0.6 and 5.6 (2.3±2.7, average±SD).

  20. On the influence of temperature on PEM fuel cell operation

    Science.gov (United States)

    Coppo, M.; Siegel, N. P.; Spakovsky, M. R. von

    The 3D implementation of a previously developed 2D PEMFC model [N.P. Siegel, M.W. Ellis, D.J. Nelson, M.R. von Spakovsky, A two-dimensional computational model of a PEMFC with liquid water transport, J. Power Sources 128 (2) (2004) 173-184; N.P. Siegel, M.W. Ellis, D.J. Nelson, M.R. von Spakovsky, Single domain PEMFC model based on agglomerate catalyst geometry, J. Power Sources 115 (2003) 81-89] has been used to analyze the various pathways by which temperature affects the operation of a proton exchange membrane fuel cell [M. Coppo, CFD analysis and experimental investigation of proton exchange membrane fuel cells, Ph.D. Dissertation, Politecnico di Torino, Turin, Italy, 2005]. The original model, implemented in a specially modified version of CFDesign ® [CFDesign ® V5.1, Blue Ridge Numerics, 2003] , accounts for all of the major transport processes including: (i) a three-phase model for water transport in the liquid, vapor and dissolved phases, (ii) proton transport, (iii) gaseous species transport and reaction, (iv) an agglomerate model for the catalyst layers and (v) gas phase momentum transport. Since the details of it have been published earlier [N.P. Siegel, M.W. Ellis, D.J. Nelson, M.R. von Spakovsky, A two-dimensional computational model of a PEMFC with liquid water transport, J. Power Sources 128 (2) (2004) 173-184; N.P. Siegel, M.W. Ellis, D.J. Nelson, M.R. von Spakovsky, Single domain PEMFC model based on agglomerate catalyst geometry, J. Power Sources 115 (2003) 81-89; N.P. Siegel, Development and validation of a computational model for a proton exchange membrane fuel cell, Ph.D. Dissertation, Virginia Polytechnic Institute and State University, Blacksburg, VA, 2003], only new features are briefly discussed in the present work. In particular, the model has been extended in order to account for the temperature dependence of all of the physical properties involved in the model formulation. Moreover, a novel model has been developed to describe liquid

  1. Identification of a novel temperature sensitive promoter in cho cells

    Directory of Open Access Journals (Sweden)

    Hesse Friedemann

    2011-05-01

    Full Text Available Abstract Background The Chinese hamster ovary (CHO expression system is the leading production platform for manufacturing biopharmaceuticals for the treatment of numerous human diseases. Efforts to optimize the production process also include the genetic construct encoding the therapeutic gene. Here we report about the successful identification of an endogenous highly active gene promoter obtained from CHO cells which shows conditionally inducible gene expression at reduced temperature. Results Based on CHO microarray expression data abundantly transcribed genes were selected as potential promoter candidates. The S100a6 (calcyclin and its flanking regions were identified from a genomic CHO-K1 lambda-phage library. Computational analyses showed a predicted TSS, a TATA-box and several TFBSs within the 1.5 kb region upstream the ATG start signal. Various constructs were investigated for promoter activity at 37°C and 33°C in transient luciferase reporter gene assays. Most constructs showed expression levels even higher than the SV40 control and on average a more than two-fold increase at lower temperature. We identified the core promoter sequence (222 bp comprising two SP1 sites and could show a further increase in activity by duplication of this minimal sequence. Conclusions This novel CHO promoter permits conditionally high-level gene expression. Upon a shift to 33°C, a two to three-fold increase of basal productivity (already higher than SV40 promoter is achieved. This property is of particular advantage for a process with reduced expression during initial cell growth followed by the production phase at low temperature with a boost in expression. Additionally, production of toxic proteins becomes feasible, since cell metabolism and gene expression do not directly interfere. The CHO S100a6 promoter can be characterized as cold-shock responsive with the potential for improving process performance of mammalian expression systems.

  2. Direct Utilization of Coal Syngas in High Temperature Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Celik, Ismail B. [West Virginia University, Morgantown, WV (United States)

    2014-10-30

    This EPSCoR project had two primary goals: (i) to build infrastructure and work force at WVU to support long-term research in the area of fuel cells and related sciences; (ii) study effects of various impurities found in coal-syngas on performance of Solid Oxide Fuel Cells (SOFC). As detailed in this report the WVU research team has made significant accomplishments in both of these areas. What follows is a brief summary of these accomplishments: State-of-the-art test facilities and diagnostic tools have been built and put into use. These include cell manufacturing, half-cell and full-cell test benches, XPS, XRD, TEM, Raman, EDAX, SEM, EIS, and ESEM equipment, unique in-situ measurement techniques and test benches (Environmental EM, Transient Mass-Spectrometer-MS, and IR Optical Temperature measurements). In addition, computational capabilities have been developed culminating in a multi-scale multi-physics fuel cell simulation code, DREAM-SOFC, as well as a Beowulf cluster with 64 CPU units. We have trained 16 graduate students, 10 postdoctoral fellows, and recruited 4 new young faculty members who have actively participated in the EPSCoR project. All four of these faculty members have already been promoted to the tenured associate professor level. With the help of these faculty and students, we were able to secure 14 research awards/contracts amounting to a total of circa $5.0 Million external funding in closely related areas of research. Using the facilities mentioned above, the effects of PH3, HCl, Cl2, and H2S on cell performance have been studied in detail, mechanisms have been identified, and also remedies have been proposed and demonstrated in the laboratory. For example, it has been determined that PH3 reacts rapidly with Ni to from secondary compounds which may become softer or even melt at high temperature and then induce Ni migration to the surface of the cell changing the material and micro-structural properties of the cell drastically. It is found that

  3. Surface tension, grain boundary energy, and diffusion coefficient of In as determined by creep experiments at temperatures close to the melting point

    International Nuclear Information System (INIS)

    The surface tension γ, grain boundary energy γsub(R) and diffusion coefficient D at 1470C were determined from the creep behaviour of thin In wires having a bamboo structure. The following values were found. γ = 674 +- 74 dyn/cm; γsub(R) = 258 +- 36 dyn/cm; D = 3.1 +- 0.4 x 1010 cm2/s. Creep is governed by the Nabarro-Herring mechanism. (orig.)

  4. Low temperature characteristic of ITO/SiO x /c-Si heterojunction solar cell

    Science.gov (United States)

    Du, H. W.; Yang, J.; Li, Y.; Gao, M.; Chen, S. M.; Yu, Z. S.; Xu, F.; Ma, Z. Q.

    2015-09-01

    Based on the temperature-dependent measurements and the numerical calculation, the temperature response of the photovoltaic parameters for a ITO/SiO x /c-Si heterojunction solar cell have been investigated in the ascending sorting of 10-300 K. Under unique energy concentrated photon irradiation with the wavelength of 405 nm and power density of 667 mW cm-2, it was found that the short-circuit current (I SC) was nonlinearly increased and the open-circuit voltage (V OC) decreased with temperature. The good passivation of the ITO/c-Si interface by a concomitant SiO x buffer layer leads to the rare recombination of carriers in the intermediate region. The inversion layer model indicated that the band gap of c-silicon was narrowed and the Fermi level of n-type silicon (E\\text{F}n ) tended to that of the intrinsic Fermi level (E\\text{F}i ) (in the middle of band gap) with the increase of the temperature, which lessened the built-in voltage (V D) and thus the V OC. However, the reduction by 90% of V OC is attributed to the shift of E\\text{F}n in c-silicon rather than the energy band narrowing. Through the analysis of the current-voltage relationship and the data fitting, we infer that the series resistance (R s) is not responsible for the increase of I SC, but the absorption coefficient and the depletion-width of c-silicon are the causes of the enhancing I SC. Mostly, the interaction of the photon-generated excess ‘cold hole’ and the acoustic phonon in n-Si would influence the variation of I ph or I SC with temperature.

  5. Effect of porous structure of catalyst layer on effective oxygen diffusion coefficient in polymer electrolyte fuel cell

    Science.gov (United States)

    Inoue, Gen; Kawase, Motoaki

    2016-09-01

    It is important to reduce the oxygen diffusion resistance through PEFC porous electrode, because it is the key to reduce the PEFC cost. However, the gas diffusion coefficient of CL is lower than MPL in spite of framework consisted of same carbon blacks. In this study, in order to understand the reasons of the lower gas diffusion performance of CL, the relationship between a carbon black agglomerate structure and ionomer adhesion condition is evaluated by a numerical analysis with an actual reconstructed structure and a simulated structure. As a result, the gas diffusion property of CL strongly depends on the ionomer adhesion shape. In the case of adhesion shape with the same curvature of ionomer interface, each pore can not be connected enough. So the pore tortuosity increases. Moreover, in the case of existence of inefficient large pores formed by carbon black agglomerate and ununiformly coated ionomer, the gas diffusion performance decrease rapidly. As the measurement values in actual CL are almost equal to that with model structure with inefficient large pores. These characteristics can be confirmed by actual cross-section image obtained by FIB-SEM.

  6. File list: DNS.Adl.05.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available DNS.Adl.05.AllAg.Temperature_sensitive_cells dm3 DNase-seq Adult Temperature sensit...ive cells http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/DNS.Adl.05.AllAg.Temperature_sensitive_cells.bed ...

  7. File list: Pol.Adl.20.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Adl.20.AllAg.Temperature_sensitive_cells dm3 RNA polymerase Adult Temperature s...ensitive cells http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Pol.Adl.20.AllAg.Temperature_sensitive_cells.bed ...

  8. File list: Pol.Adl.10.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Adl.10.AllAg.Temperature_sensitive_cells dm3 RNA polymerase Adult Temperature s...ensitive cells http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Pol.Adl.10.AllAg.Temperature_sensitive_cells.bed ...

  9. File list: Unc.Adl.20.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Unc.Adl.20.AllAg.Temperature_sensitive_cells dm3 Unclassified Adult Temperature sen...sitive cells http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Unc.Adl.20.AllAg.Temperature_sensitive_cells.bed ...

  10. File list: Pol.Adl.50.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Adl.50.AllAg.Temperature_sensitive_cells dm3 RNA polymerase Adult Temperature s...ensitive cells http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Pol.Adl.50.AllAg.Temperature_sensitive_cells.bed ...

  11. File list: Oth.Adl.50.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Adl.50.AllAg.Temperature_sensitive_cells dm3 TFs and others Adult Temperature s...ensitive cells SRX699115 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.Adl.50.AllAg.Temperature_sensitive_cells.bed ...

  12. File list: Oth.Adl.10.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Adl.10.AllAg.Temperature_sensitive_cells dm3 TFs and others Adult Temperature s...ensitive cells SRX699115 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.Adl.10.AllAg.Temperature_sensitive_cells.bed ...

  13. File list: Oth.Adl.20.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Adl.20.AllAg.Temperature_sensitive_cells dm3 TFs and others Adult Temperature s...ensitive cells SRX699115 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.Adl.20.AllAg.Temperature_sensitive_cells.bed ...

  14. File list: Unc.Adl.10.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Unc.Adl.10.AllAg.Temperature_sensitive_cells dm3 Unclassified Adult Temperature sen...sitive cells http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Unc.Adl.10.AllAg.Temperature_sensitive_cells.bed ...

  15. File list: Unc.Adl.05.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Unc.Adl.05.AllAg.Temperature_sensitive_cells dm3 Unclassified Adult Temperature sen...sitive cells http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Unc.Adl.05.AllAg.Temperature_sensitive_cells.bed ...

  16. File list: Unc.Adl.50.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Unc.Adl.50.AllAg.Temperature_sensitive_cells dm3 Unclassified Adult Temperature sen...sitive cells http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Unc.Adl.50.AllAg.Temperature_sensitive_cells.bed ...

  17. File list: Oth.Adl.05.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Oth.Adl.05.AllAg.Temperature_sensitive_cells dm3 TFs and others Adult Temperature s...ensitive cells SRX699115 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Oth.Adl.05.AllAg.Temperature_sensitive_cells.bed ...

  18. File list: DNS.Adl.10.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available DNS.Adl.10.AllAg.Temperature_sensitive_cells dm3 DNase-seq Adult Temperature sensit...ive cells http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/DNS.Adl.10.AllAg.Temperature_sensitive_cells.bed ...

  19. File list: DNS.Adl.20.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available DNS.Adl.20.AllAg.Temperature_sensitive_cells dm3 DNase-seq Adult Temperature sensit...ive cells http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/DNS.Adl.20.AllAg.Temperature_sensitive_cells.bed ...

  20. File list: Pol.Adl.05.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available Pol.Adl.05.AllAg.Temperature_sensitive_cells dm3 RNA polymerase Adult Temperature s...ensitive cells http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/Pol.Adl.05.AllAg.Temperature_sensitive_cells.bed ...

  1. Optimization of temperature, sugar concentration, and inoculum size to maximize ethanol production without significant decrease in yeast cell viability

    Energy Technology Data Exchange (ETDEWEB)

    Laluce, Cecilia; Morais, Meline Rezende [Inst. de Quimica de Araraquara-UNESP, SP (Brazil). Dept. of Biochemistry and Biotechnological Chemistry; Tognolli, Joao Olimpio [Inst. de Quimica de Araraquara-UNESP, SP (Brazil). Dept. of Analytical Chemistry; Oliveira, Karen Fernanda de; Souza, Crisla Serra [Cidade Universitaria, Sao Paulo, SP (Brazil). Programa de Pos-Graduacao Interunidades em Biotecnologia

    2009-06-15

    Aiming to obtain rapid fermentations with high ethanol yields and a retention of high final viabilities (responses), a 2{sup 3} full-factorial central composite design combined with response surface methodology was employed using inoculum size, sucrose concentration, and temperature as independent variables. From this statistical treatment, two well-fitted regression equations having coefficients significant at the 5% level were obtained to predict the viability and ethanol production responses. Three-dimensional response surfaces showed that increasing temperatures had greater negative effects on viability than on ethanol production. Increasing sucrose concentrations improved both ethanol production and viability. The interactions between the inoculum size and the sucrose concentrations had no significant effect on viability. Thus, the lowering of the process temperature is recommended in order to minimize cell mortality and maintain high levels of ethanol production when the temperature is on the increase in the industrial reactor. Optimized conditions (200 g/l initial sucrose, 40 g/l of dry cell mass, 30 C) were experimentally confirmed and the optimal responses are 80.8{+-}2.0 g/l of maximal ethanol plus a viability retention of 99.0{+-}3.0% for a 4-h fermentation period. During consecutive fermentations with cell reuse, the yeast cell viability has to be kept at a high level in order to prevent the collapse of the process. (orig.)

  2. Low temperature tolerance of human embryonic stem cells

    Directory of Open Access Journals (Sweden)

    Boon Chin Heng, Kumar Jayaseelan Vinoth, Hua Liu, Manoor Prakash Hande, Tong Cao

    2006-01-01

    Full Text Available This study investigated the effects of exposing human embryonic stem cells (hESC to 4oC and 25oC for extended durations of 24h and 48h respectively. Cell survivability after low temperature exposure was assessed through the MTT assay. The results showed that hESC survivability after exposure to 25oC and 4oC for 24h was 77.3 ± 4.8 % and 64.4 ± 4.4 % respectively (significantly different, P < 0.05. The corresponding survival rates after 48h exposure to 25oC and 4oC was 71.0 ± 0.5 % and 69.0 ± 2.3 % respectively (not significantly different, P > 0.05. Spontaneous differentiation of hESC after low temperature exposure was assessed by morphological observations under bright-field and phase-contrast microscopy, and by immunocytochemical staining for the pluripotency markers SSEA-3 and TRA-1-81. hESC colonies were assigned into 3 grades according to their degree of spontaneous differentiation: (1 Grade A which was completely or mostly undifferentiated, (2 Grade B which was partially differentiated, and (3 Grade C which was mostly differentiated. In all low temperature exposed groups, about 95% of colonies remain undifferentiated (Grade A, which was not significantly different (P > 0.05 from the unexposed control group maintained at 37oC. Additionally, normal karyotype was maintained in all low temperature-exposed groups, as assessed by fluorescence in situ hybridization (FISH of metaphase spreads with telomere and centromere-specific PNA probes. Further analysis with m-FISH showed that chromosomal translocations were absent in all experimental groups. Hence, hESC possess relatively high-tolerance to extended durations of low temperature exposure, which could have useful implications for the salvage of hESC culture during infrequent occurrences of incubator break-down and power failure.

  3. Magnetic resonance imaging in children with sickle cell disease - detecting alterations in the apparent diffusion coefficient in hips with avascular necrosis

    Energy Technology Data Exchange (ETDEWEB)

    MacKenzie, John D. [Children' s Hospital of Philadelphia, Department of Pediatric Radiology, Philadelphia, PA (United States); UCSF Benioff Children' s Hospital, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States); Hernandez, Andrea; Pena, Andres; Khrichenko, Dmitry; Gonzalez, Leonardo; Jaramillo, Diego [Children' s Hospital of Philadelphia, Department of Pediatric Radiology, Philadelphia, PA (United States); Ruppert, Kai [Children' s Hospital of Philadelphia, Department of Pediatric Radiology, Philadelphia, PA (United States); University of Virginia, Department of Radiology, Charlottesville, VA (United States); Jawad, Abbas F. [Children' s Hospital of Philadelphia, Department of Pediatrics, Philadelphia, PA (United States); Wells, Lawrence [Children' s Hospital of Philadelphia, Department of Orthopedics, Philadelphia, PA (United States); Smith-Whitley, Kim [Children' s Hospital of Philadelphia, Department of Hematology, Philadelphia, PA (United States)

    2012-06-15

    Avascular necrosis (AVN) is a common morbidity in children with sickle cell disease (SCD) that leads to pain and joint immobility. However, the diagnosis is often uncertain or delayed. To examine the ability of apparent diffusion coefficient (ADC) measurements on diffusion-weighted imaging to detect AVN in children with SCD. ADC values were calculated at the hips of normal children (n = 19) and children with SCD who were either asymptomatic with no known previous hip disease (n = 13) or presented for the first time with clinical symptoms of hip pathology (n = 12). ADC values were compared for differences among groups with and without AVN using non-parametric statistical methods. The ADC values were elevated in the hips of children with AVN (median ADC = 1.57 x 10{sup -3} mm{sup 2}/s [95% confidence interval = 0.86-2.10]) and differed significantly in pairwise comparisons (all P < 0.05) from normal children (0.74 [0.46-0.98]), asymptomatic children with SCD (0.55 [0.25-0.85]), and SCD children who had symptoms referable to their hips but did not show findings of hip AVN on conventional MRI or radiographs (0.46 [0.18-0.72]). Children with sickle cell disease have elevated apparent diffusion coefficient values in their affected hips on initial diagnosis of avascular necrosis. (orig.)

  4. Magnetic resonance imaging in children with sickle cell disease - detecting alterations in the apparent diffusion coefficient in hips with avascular necrosis

    International Nuclear Information System (INIS)

    Avascular necrosis (AVN) is a common morbidity in children with sickle cell disease (SCD) that leads to pain and joint immobility. However, the diagnosis is often uncertain or delayed. To examine the ability of apparent diffusion coefficient (ADC) measurements on diffusion-weighted imaging to detect AVN in children with SCD. ADC values were calculated at the hips of normal children (n = 19) and children with SCD who were either asymptomatic with no known previous hip disease (n = 13) or presented for the first time with clinical symptoms of hip pathology (n = 12). ADC values were compared for differences among groups with and without AVN using non-parametric statistical methods. The ADC values were elevated in the hips of children with AVN (median ADC = 1.57 x 10-3 mm2/s [95% confidence interval = 0.86-2.10]) and differed significantly in pairwise comparisons (all P < 0.05) from normal children (0.74 [0.46-0.98]), asymptomatic children with SCD (0.55 [0.25-0.85]), and SCD children who had symptoms referable to their hips but did not show findings of hip AVN on conventional MRI or radiographs (0.46 [0.18-0.72]). Children with sickle cell disease have elevated apparent diffusion coefficient values in their affected hips on initial diagnosis of avascular necrosis. (orig.)

  5. Low temperature rate coefficients of the H + CH{sup +} → C{sup +} + H{sub 2} reaction: New potential energy surface and time-independent quantum scattering

    Energy Technology Data Exchange (ETDEWEB)

    Werfelli, Ghofran [Université de Bordeaux, Institut des Sciences Moléculaires, CNRS UMR 5255, 33405 Talence Cedex (France); Faculté des Sciences de Tunis, Université de Tunis El-Manar, Laboratoire de Physique de la Matière Condensée, 2092 Tunis (Tunisia); Halvick, Philippe; Stoecklin, Thierry [Université de Bordeaux, Institut des Sciences Moléculaires, CNRS UMR 5255, 33405 Talence Cedex (France); Honvault, Pascal [Université de Bourgogne Franche-Comté, Laboratoire Interdisciplinaire Carnot de Bourgogne, CNRS UMR 6303, 21078 Dijon Cedex (France); Université de Franche-Comté, UFR ST, 25030 Besançon Cedex (France); Kerkeni, Boutheïna [Faculté des Sciences de Tunis, Université de Tunis El-Manar, Laboratoire de Physique de la Matière Condensée, 2092 Tunis (Tunisia); Institut Supérieur des Arts Multimédia de la Manouba, Université de la Manouba, 2010 la Manouba (Tunisia)

    2015-09-21

    The observed abundances of the methylidyne cation, CH{sup +}, in diffuse molecular clouds can be two orders of magnitude higher than the prediction of the standard gas-phase models which, in turn, predict rather well the abundances of neutral CH. It is therefore necessary to investigate all the possible formation and destruction processes of CH{sup +} in the interstellar medium with the most abundant species H, H{sub 2}, and e{sup −}. In this work, we address the destruction process of CH{sup +} by hydrogen abstraction. We report a new calculation of the low temperature rate coefficients for the abstraction reaction, using accurate time-independent quantum scattering and a new high-level ab initio global potential energy surface including a realistic model of the long-range interaction between the reactants H and CH{sup +}. The calculated thermal rate coefficient is in good agreement with the experimental data in the range 50 K–800 K. However, at lower temperatures, the experimental rate coefficient takes exceedingly small values which are not reproduced by the calculated rate coefficient. Instead, the latter rate coefficient is close to the one given by the Langevin capture model, as expected for a reaction involving an ion and a neutral species. Several recent theoretical works have reported a seemingly good agreement with the experiment below 50 K, but an analysis of these works show that they are based on potential energy surfaces with incorrect long-range behavior. The experimental results were explained by a loss of reactivity of the lowest rotational states of the reactant; however, the quantum scattering calculations show the opposite, namely, a reactivity enhancement with rotational excitation.

  6. Thin-film copper indium gallium selenide solar cell based on low-temperature all-printing process.

    Science.gov (United States)

    Singh, Manjeet; Jiu, Jinting; Sugahara, Tohru; Suganuma, Katsuaki

    2014-09-24

    In the solar cell field, development of simple, low-cost, and low-temperature fabrication processes has become an important trend for energy-saving and environmental issues. Copper indium gallium selenide (CIGS) solar cells have attracted much attention due to the high absorption coefficient, tunable band gap energy, and high efficiency. However, vacuum and high-temperature processing in fabrication of solar cells have limited the applications. There is a strong need to develop simple and scalable methods. In this work, a CIGS solar cell based on all printing steps and low-temperature annealing is developed. CIGS absorber thin film is deposited by using dodecylamine-stabilized CIGS nanoparticle ink followed by printing buffer layer. Silver nanowire (AgNW) ink and sol-gel-derived ZnO precursor solution are used to prepare a highly conductive window layer ZnO/[AgNW/ZnO] electrode with a printing method that achieves 16 Ω/sq sheet resistance and 94% transparency. A CIGS solar cell based on all printing processes exhibits efficiency of 1.6% with open circuit voltage of 0.48 V, short circuit current density of 9.7 mA/cm(2), and fill factor of 0.34 for 200 nm thick CIGS film, fabricated under ambient conditions and annealed at 250 °C. PMID:25180569

  7. DEGRADATION ISSUES IN SOLID OXIDE CELLS DURING HIGH TEMPERATURE ELECTROLYSIS

    Energy Technology Data Exchange (ETDEWEB)

    J. E. O' Brien; C. M. Stoots; V. I. Sharma; B. Yildiz; A. V. Virkar

    2010-06-01

    Idaho National Laboratory (INL) is performing high-temperature electrolysis research to generate hydrogen using solid oxide electrolysis cells (SOECs). The project goals are to address the technical and degradation issues associated with the SOECs. This paper provides a summary of various ongoing INL and INL sponsored activities aimed at addressing SOEC degradation. These activities include stack testing, post-test examination, degradation modeling, and a list of issues that need to be addressed in future. Major degradation issues relating to solid oxide fuel cells (SOFC) are relatively better understood than those for SOECs. Some of the degradation mechanisms in SOFCs include contact problems between adjacent cell components, microstructural deterioration (coarsening) of the porous electrodes, and blocking of the reaction sites within the electrodes. Contact problems include delamination of an electrode from the electrolyte, growth of a poorly (electronically) conducting oxide layer between the metallic interconnect plates and the electrodes, and lack of contact between the interconnect and the electrode. INL’s test results on high temperature electrolysis (HTE) using solid oxide cells do not provide a clear evidence whether different events lead to similar or drastically different electrochemical degradation mechanisms. Post-test examination of the solid oxide electrolysis cells showed that the hydrogen electrode and interconnect get partially oxidized and become non-conductive. This is most likely caused by the hydrogen stream composition and flow rate during cool down. The oxygen electrode side of the stacks seemed to be responsible for the observed degradation due to large areas of electrode delamination. Based on the oxygen electrode appearance, the degradation of these stacks was largely controlled by the oxygen electrode delamination rate. University of Utah (Virkar) has developed a SOEC model based on concepts in local thermodynamic equilibrium in

  8. Viscosity coefficient with pairing interaction

    International Nuclear Information System (INIS)

    In the study of dynamic process (for example, deep-inelastic scattering of heavy ion, nuclear fission), viscosity, which describes the coupling between the intrinsic degrees of freedom and the collective one, is a basic quantity. In this paper, under BCS approximation, we derive a microscopic expression of viscosity coefficient with pairing interaction by means of a linear response theory. Taking the fission process of 236U as an example, we discuss the effect of pairing interaction on the viscosity coefficient. The results show that pairing interaction must be taken into account at lower temperature and can be neglected at a high-temperature region

  9. Permanent cell lines established from ts-COS cells that regulate by temperature the amplification and expression of cloned genes.

    OpenAIRE

    de la Luna, S; A. Portela; Martínez, C; Ortín, J

    1987-01-01

    Temperature-sensitive COS cells have been transformed at restrictive temperature with SV40 replicons containing the neo or pac markers. Puromycin-resistant cell clones maintained at the restrictive temperature contain the pac gene integrated into the cell DNA. However, when the cells are shifted to the permissive temperature the pac gene is amplified in episomal forms up to 2-4 X 10(4) copies per cell. Concomitant with this, an induction of 35-300 fold in the levels of puromycin acetyl transf...

  10. Doubling the annual coefficient of performance of air-conditioning units by taking advantage of small temperature lifts; Verdoppelung der Jahresarbeitszahl von Klimakaelteanlagen durch Ausnuetzung eines kleinen Temperaturhubes

    Energy Technology Data Exchange (ETDEWEB)

    Wellig, B.; Kegel, B.; Meier, M.

    2006-07-01

    The seasonal performance factor (SPF) of chilled water systems (CWS) is closely related to the temperature lift, i.e. the difference between the temperature of the heat source and the heat sink. In many applications in building services engineering, a temperature lift of 10-20 K is in principle sufficient. However, the potential for highly efficient refrigerating systems is not fully exploited as standard chillers are designed for lifts of 30-60 K. The exergy analysis of typical CWS shows that the external exergy losses are greater than the exergy losses of the chiller. The second-law (or exergetic) efficiency is usually far below 10%. It is therefore important to avoid unnecessarily high temperature lifts. Measurements on refrigeration systems in two office buildings have shown that even in state-of-the-art CWS, considerable energy savings (up to 50%) can be achieved by persistent use of small temperature lifts. However, SPF-values around 5-6 can hardly be exceeded in systems with electric driven chillers. SPFs higher than 10 or even above 20 can only be reached with optimized free cooling processes. Basic decisions, which ultimately lead to CWS with unnecessarily high temperature lifts, are taken in the early project stages. Therefore, this study presents guidelines for the design and operation of CWS with small temperature lifts. The implementation of these simple measures will lead to a considerable reduction of energy consumption and operating costs. (author)

  11. Modelling the impact of blood flow on the temperature distribution in the human eye and the orbit: fixed heat transfer coefficients versus the Pennes bioheat model versus discrete blood vessels

    International Nuclear Information System (INIS)

    Prediction of the temperature distribution in the eye depends on how the impact of the blood flow is taken into account. Three methods will be compared: a simplified eye anatomy that applies a single heat transfer coefficient to describe all heat transport mechanisms between the sclera and the body core, a detailed eye anatomy in which the blood flow is accounted for either by the bioheat approach, or by including the discrete vasculature in the eye and the orbit. The comparison is done both for rabbit and human anatomies, normo-thermally and when exposed to homogeneous power densities. The first simplified model predicts much higher temperatures than the latter two. It was shown that the eye is very hard to heat when taking physiological perfusion correctly into account. It was concluded that the heat transfer coefficient describing the heat transport from the sclera to the body core reported in the literature for the first simplified model is too low. The bioheat approach is appropriate for a first-order approximation of the temperature distribution in the eye when exposed to a homogeneous power density, but the discrete vasculature down to 0.2 mm in diameter needs to be taken into account when the heterogeneity of the temperature distribution at a mm scale is of interest

  12. Graphite friction coefficient for various conditions

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The friction coefficient the graphite used in the Tsinghua University 10MW High Tem-perature Gas-Cooled Reactor was analyzed for various conditions. The variation of the graphitefriction coefficient was measured for various sliding velocities, sliding distances, normal loads, en-vironments and temperatures. A scanning elector microscope (SEM) was used to analyze the fric-tion surfaces.

  13. Enhanced room temperature coefficient of resistance and magnetoresistance of Ag-added La{sub 0.7}Ca{sub 0.3-x}Ba{sub x}MnO{sub 3} composites

    Energy Technology Data Exchange (ETDEWEB)

    Tripathi, Rahul; Awana, V P S; Agarwal, S K; Kishan, H [National Physical Laboratory, Dr K S Krishnan Marg, New Delhi-110012 (India); Panwar, Neeraj [Department of Physics, Indian Institute of Technology, New Delhi-110016 (India); Bhalla, G L [Department of Physics and Astrophysics, University of Delhi, Delhi-1100007 (India); Habermier, H U, E-mail: awana@mail.nplindia.ernet.i [Max Planck Institut fur Festkoerperforschung, Heisenbergstrasse-70569, Stuttgart (Germany)

    2009-09-07

    In this paper we report an enhanced temperature coefficient of resistance (TCR) close to room temperature in La{sub 0.7}Ca{sub 0.3-x}Ba{sub x}MnO{sub 3} + Ag{sub y} (x = 0.10, 0.15 and 0 {<=} y {<=} 1.0) (LCBMO + Ag) composite manganites. The observed enhancement of TCR is attributed to the grain growth and opening of new conducting channels in the composites. Ag addition has also been found to enhance intragranular magnetoresistance. Intergranular MR, however, is seen to decrease with Ag addition. The enhanced TCR and MR at/near room temperature open up the possibility of the use of such materials as infrared bolometric and magnetic field sensors, respectively.

  14. Interconnects for intermediate temperature solid oxide fuel cells

    Science.gov (United States)

    Huang, Wenhua

    Presently, one of the principal goals of solid oxide fuel cells (SOFCs) research is to reduce the stack operating temperature to between 600 and 800°C. However, one of the principal technological barriers is the non-availability of a suitable material satisfying all of the stability requirements for the interconnect. In this work two approaches for intermediate temperature SOFC interconnects have been explored. The first approach comprises an interconnect consisting of a bi-layer structure, a p-type oxide (La0.96Sr0.08MnO 2.001/LSM) layer exposed to a cathodic environment, and an n-type oxide (Y0.08Sr0.88Ti0.95Al0.05O 3-delta/YSTA) layer exposed to anodic conditions. Theoretical analysis based on the bi-layer structure has established design criteria to implement this approach. The analysis shows that the interfacial oxygen partial pressure, which determines the interconnect stability, is independent of the electronic conductivities of both layers but dependent on the oxygen ion layer interconnects, the oxygen ion conductivities of LSM and YSTA were measured as a function of temperature and oxygen partial pressure. Based on the measured data, it has been determined that if the thickness of YSTA layer is around 0.1cm, the thickness of LSM layer should be around 0.6 mum in order to maintain the stability of LSM. In a second approach, a less expensive stainless steel interconnect has been studied. However, one of the major concerns associated with the use of metallic interconnects is the development of a semi-conducting or insulating oxide scale and chromium volatility during extended exposure to the SOFC operating environment. Dense and well adhered Mn-Cu spinet oxide coatings were successfully deposited on stainless steel by an electrophoretic deposition (EPD) technique. It was found that the Mn-Cu-O coating significantly reduced the oxidation rate of the stainless steel and the volatility of chromium. The area specific resistance (ASR) of coated Crofer 22 APU is

  15. Experimental investigations for determination of heat-transfer coefficients and temperature fields in simulated fuel assemblies of BREST reactor with fuel elements spaced by transverse grids

    International Nuclear Information System (INIS)

    The consideration is given to heat transfer and temperature fields in fuel pin bundles with transverse spacer grids (s/d =1.33) equally spaced along energy deposition length. Experimental data are obtained on two simulated 37-rod core assemblies: one assembly is with uniform geometry along the cross-section and in the other there is nonheated rod simulating supporting pipe in fuel assembly of reactor with heavy coolant. Eutectic Na-K alloy is used as coolant. Nusselt numbers and temperature nonuniformity along the perimeter of measurement fuel element simulator obtained in these assemblies are compared as well as available data for finned (wire to wire) fuel rods

  16. Temperature Characteristics Analysis of Triple-Junction Solar Cell under Concentrated Conditions using Spice Diode Model

    Science.gov (United States)

    Sakurada, Yuya; Ota, Yasuyuki; Nishioka, Kensuke

    2011-12-01

    Using spice diode model, the temperature characteristics of an InGaP/InGaAs/Ge triple-junction solar cell under concentrated light conditions were analyzed in detail. The current-voltage (I-V) characteristics of the single-junction solar cells (InGaP, InGaAs, and Ge solar cells) were measured at various temperatures. From dark I-V characteristics of each single-junction solar cell, the diode parameters and temperature exponents were extracted. The extracted diode parameters and temperature exponents were applied to the equivalent circuit model for the triple-junction solar cell, and the solar cell performance was calculated with considering the temperature characteristics of series resistance. There was good agreement between the measured and calculated I-V characteristics of the triple-junction solar cell at various temperatures under concentrated light conditions.

  17. Solar cell contact pull strength as a function of pull-test temperature

    Science.gov (United States)

    Yasui, R. K.; Berman, P. A.

    1972-01-01

    Four types of solar cell contacts were given pull-strength tests at temperatures between -173 and +165 C. Contacts tested were: (1) solder-coated titanium-silver contacts on n-p cells, (2) palladium-containing titanium-silver contacts on n-p cells, (3) titanium-silver contacts on 0.2-mm-thick n-p cells, and (4) solder-coated electroless-nickel-plated contacts on p-n cells. Maximum pull strength was demonstrated at temperatures significantly below the air mass zero cell equilibrium temperature of +60 C. At the lowest temperatures, the chief failure mechanism was silicon fracture along crystallographic planes; at the highest temperatures, it was loss of solder strength. In the intermediate temperatures, many failure mechanisms operated. Pull-strength tests give a good indication of the suitability of solar cell contact systems for space use. Procedures used to maximize the validity of the results are described.

  18. Thermal modeling and temperature control of a PEM fuel cell system for forklift applications

    DEFF Research Database (Denmark)

    Liso, Vincenzo; Nielsen, Mads Pagh; Kær, Søren Knudsen;

    2014-01-01

    Temperature changes in PEM fuel cell stacks are considerably higher during load variations and have a negative impact as they generate thermal stresses and stack degradation. Cell hydration is also of vital importance in fuel cells and it is strongly dependent on operating temperature. A combinat......Temperature changes in PEM fuel cell stacks are considerably higher during load variations and have a negative impact as they generate thermal stresses and stack degradation. Cell hydration is also of vital importance in fuel cells and it is strongly dependent on operating temperature. A...... combination of high temperature and reduced humidity increases the degradation rate. Stack thermal management and control are, thus, crucial issues in PEM fuel cell systems especially in automotive applications such as forklifts. In this paper we present a control–oriented dynamic model of a liquid–cooled PEM...... designers in choosing the required coolant mass flow rate and radiator size to minimize the stack temperature gradients....

  19. File list: ALL.Adl.50.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Adl.50.AllAg.Temperature_sensitive_cells dm3 All antigens Adult Temperature sen...811237 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/ALL.Adl.50.AllAg.Temperature_sensitive_cells.bed ...

  20. File list: ALL.Adl.10.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Adl.10.AllAg.Temperature_sensitive_cells dm3 All antigens Adult Temperature sen...811238 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/ALL.Adl.10.AllAg.Temperature_sensitive_cells.bed ...

  1. File list: ALL.Adl.05.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Adl.05.AllAg.Temperature_sensitive_cells dm3 All antigens Adult Temperature sen...699108 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/ALL.Adl.05.AllAg.Temperature_sensitive_cells.bed ...

  2. File list: ALL.Adl.20.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available ALL.Adl.20.AllAg.Temperature_sensitive_cells dm3 All antigens Adult Temperature sen...699108 http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/ALL.Adl.20.AllAg.Temperature_sensitive_cells.bed ...

  3. Modelling and Evaluation of Heating Strategies for High Temperature Polymer Electrolyte Membrane Fuel Cell Stacks

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen

    2008-01-01

    Experiments were conducted on two different cathode air cooled high temperature PEM (HTPEM) fuel cell stacks; a 30 cell 400W prototype stack using two bipolar plates per cell, and a 65 cell 1 kW commercial stack using one bipolar plate per cell. The work seeks to examine the use of different...

  4. Attractions in sterically stabilized silica dispersions : III. Second virial coefficient as a function of temperature, as measured by means of turbidity

    NARCIS (Netherlands)

    Jansen, J.W.; Kruif, C.G. de; Vrij, A.

    1986-01-01

    Silica particles coated with octadecyl chains and dispersed in toluene exhibit attractions on lowering the temperature. The attraction is supposed to be the result of interactions between the chain segments and solvent. Since light is strongly scattered in the dispersions turbidity measurements are

  5. Temperature gradient stimulation for cell division in C. Elegans Embryos on chip

    OpenAIRE

    Baranek, Sophie; Bezler, Alexandra; Adamczyk, Christian; Gönczy, Pierre; Renaud, Philippe

    2010-01-01

    This paper reports on a new microfluidic device for temperature stimulation of cell in in-vitro culture. Micro-electrodes in a meander shape are embedded into the microfluidic channels to generate either a temperature gradient through the culture chamber or a local heat spot under specific cells. One promising application is the control of cell di- vision rate. Here we present first results of the synchronization of cell division in a two-cell stage embryos of C. Elegans.

  6. Modelling of a High Temperature PEM Fuel Cell Stack using Electrochemical Impedance Spectroscopy

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Jespersen, Jesper Lebæk; Kær, Søren Knudsen

    2008-01-01

    This work presents the development of an equivalent circuit model of a 65 cell high temperature PEM (HTPEM) fuel cell stack using Electrochemical Impedance Spectroscopy (EIS). The HTPEM fuel cell membranes used are PBI-based and uses phosphoric acid as proton conductor. The operating temperature of...

  7. An Aurivillius Oxide Based Cathode with Excellent CO2 Tolerance for Intermediate-Temperature Solid Oxide Fuel Cells.

    Science.gov (United States)

    Zhu, Yinlong; Zhou, Wei; Chen, Yubo; Shao, Zongping

    2016-07-25

    The Aurivillius oxide Bi2 Sr2 Nb2 MnO12-δ (BSNM) was used as a cobalt-free cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). To the best of our knowledge, the BSNM oxide is the only alkaline-earth-containing cathode material with complete CO2 tolerance that has been reported thus far. BSNM not only shows favorable activity in the oxygen reduction reaction (ORR) at intermediate temperatures but also exhibits a low thermal expansion coefficient, excellent structural stability, and good chemical compatibility with the electrolyte. These features highlight the potential of the new BSNM material as a highly promising cathode material for IT-SOFCs. PMID:27294808

  8. Development of a 400 W High Temperature PEM Fuel Cell Power Pack:Fuel Cell Stack Test

    OpenAIRE

    Andreasen, Søren Juhl; Bang, Mads; Korsgaard, Anders; Nielsen, Mads Pagh; Kær, Søren Knudsen

    2006-01-01

    When using pressurized hydrogen to fuel a fuel cell, much space is needed for fuel storage. This is undesirable especially with mobile or portable fuel cell systems, where refuelling also often is inconvenient. Using a reformed liquid carbonhydrate can reduce this fuel volume considerably. Nafion based low temperature PEM (LTPEM) fuel cells are very intolerant to reformate gas because of the presence of CO. PBI based high temperature PEM (HTPEM) fuel cells can operate stable at much higher CO...

  9. High temperature coefficient of resistance achieved by ion beam assisted sputtering with no heat treatment in VyM1−yOx (M = Nb, Hf)

    International Nuclear Information System (INIS)

    Thermal imaging based on room temperature bolometer sensors is a growing market, constantly searching for improved sensitivity. One important factor is the temperature coefficient of resistance (TCR), i.e., the sensitivity of the active material. Herein, the authors report the improved TCR properties attainable by the “ion beam assisted deposition” method for room temperature deposition. VyM1−yOx (M = Nb, Hf) thin-film alloys were fabricated on 1 μm thermal SiO2 atop Si (100) substrates by reactive magnetron cosputtering at room temperature using a low energy ion source, aimed at the film, to insert dissociated oxygen species and increase film density. The authors studied the influence of deposition parameters such as oxygen partial pressure, V to M ratio, and power of the plasma source, on resistance and TCR. The authors show high TCR (up to −3.7% K−1) at 300 K, and excellent uniformity, but also an increase in resistance. The authors emphasize that samples were prepared at room temperature with no heat treatment, much simpler than common processes that require annealing at high temperatures. So, this is a promising fabrication route for uncooled microbolometers

  10. High temperature coefficient of resistance achieved by ion beam assisted sputtering with no heat treatment in V{sub y}M{sub 1−y}O{sub x} (M = Nb, Hf)

    Energy Technology Data Exchange (ETDEWEB)

    Vardi, Naor; Sharoni, Amos, E-mail: amos.sharoni@biu.ac.il [Department of Physics and Institute of Nanoscience and Advanced Materials, Bar-Ilan University, Ramat-Gan 5290002 (Israel)

    2015-11-15

    Thermal imaging based on room temperature bolometer sensors is a growing market, constantly searching for improved sensitivity. One important factor is the temperature coefficient of resistance (TCR), i.e., the sensitivity of the active material. Herein, the authors report the improved TCR properties attainable by the “ion beam assisted deposition” method for room temperature deposition. V{sub y}M{sub 1−y}O{sub x} (M = Nb, Hf) thin-film alloys were fabricated on 1 μm thermal SiO{sub 2} atop Si (100) substrates by reactive magnetron cosputtering at room temperature using a low energy ion source, aimed at the film, to insert dissociated oxygen species and increase film density. The authors studied the influence of deposition parameters such as oxygen partial pressure, V to M ratio, and power of the plasma source, on resistance and TCR. The authors show high TCR (up to −3.7% K{sup −1}) at 300 K, and excellent uniformity, but also an increase in resistance. The authors emphasize that samples were prepared at room temperature with no heat treatment, much simpler than common processes that require annealing at high temperatures. So, this is a promising fabrication route for uncooled microbolometers.

  11. Low temperature surface passivation for silicon solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Leguijt, C.; Loelgen, P.; Eikelboom, J.A.; Weeber, A.W.; Schuurmans, F.M.; Sinke, W.C. [Netherlands Energy Research Foundation ECN, Petten (Netherlands); Alkemade, P.F.A.; Sarro, P.M. [Delft Institute for MicroElectronics and Submicron Technology DIMES, Delft (Netherlands); Maree, C.H.M. [Department of Atomic and Interface Physics, Debye Institute, University of Utrecht, Utrecht (Netherlands); Verhoef, L.A. [R and S Renewable Energy Systems B.V., Helmond (Netherlands)

    1996-07-18

    Surface passivation at low processing temperatures becomes an important topic for cheap solar cell processing. In this study, we first give a broad overview of the state of the art in this field. Subsequently, the results of a series of mutually related experiments are given about surface passivation with direct Plasma Enhanced Chemical Vapour Deposition (PECVD) of silicon oxide (Si-oxide) and silicon nitride (Si-nitride). Results of harmonically modulated microwave reflection experiments are combined with Capacitance-Voltage measurements on Metal-Insulator-Silicon structures (CV-MIS), accelerated degradation tests and with Secondary Ion Mass Spectrometry (SIMS) and Elastic Recoil Detection (ERD) measurements of hydrogen and deuterium concentrations in the passivating layers. A large positive fixed charge density at the interface is very important for the achieved low surface recombination velocities S. The density of interface states D{sub i}t is strongly reduced by post deposition anneals. The lowest values of S are obtained with PECVD of Si-nitride. The surface passivation obtained with Si-nitride is stable under typical operating conditions for solar cells. By using deuterium as a tracer it is shown that hydrogen in the ambient of the post deposition anneal does not play a role in the passivation by Si-nitride. Finally, the results of CV-MIS measurements on deposited Si-nitride layers are used to calculate effective recombination velocities as a function of the injection level at the surface, using a model that is able to predict the surface recombination velocity S at thermally oxidized silicon surfaces. These results are not in agreement with the measured increase of S at low injection levels

  12. The temperature influence in the toluene diffusion coefficient in type y zeolites; Influencia da temperatura no coeficiente de difusao do tolueno em zeolitas do tipo Y

    Energy Technology Data Exchange (ETDEWEB)

    Schwanke, R.O.; Chagas, C.U.; Souza, S.M.A. Guelli U.; Souza, A.A. Ulson de [Santa Catarina Univ., Florianopolis, SC (Brazil). Dept. de Engenharia Quimica e Engenharia de Alimentos]. E-mail: augusto@enq.ufsc.br; Oliveira, J.S. [Parana Univ., Curitiba, PR (Brazil). Dept. de Engenharia Quimica]. E-mail: juarzoli@engquim.ufpr.br; Maliska, C.R. [Santa Catarina Univ., Florianopolis, SC (Brazil). Dept. de Engenharia Mecanica]. E-mail: maliska@sinmec.ufsc.br

    2003-07-01

    This study presents the results of the toluene intra crystalline diffusivity in pellets of Y-type zeolite, packed in a fixed bed column. For the evaluation of the adsorption dynamics, High Performance Liquid Chromatography (HPLC) technique was utilized, which promotes the adsorption of liquids in extremely small and uniforms particles to generate a high sensibility. The equilibrium and kinetics adsorption parameters were obtained through the pulse chromatography technique and evaluated by the method of moments, based on the analysis of the first and second statistical moments of the chromatographic response peaks. The experiment was performed with changes in the diffusional properties of the eluent/sorbate/adsorbent system, such as feeding flow and temperature. The equilibrium constant, the adsorption energy and the temperature influence over toluene diffusivity were determined. (author)

  13. Investigation of light intensity and temperature dependency of solar cells electric parameters

    OpenAIRE

    Tobnaghi, Davoud Mostafa; Madatov, Rahim; Farhadi, Payam

    2013-01-01

    In this paper, the performance and overview use of solar cells is expressed. The role of temperature, sunlight intensity on the solar cells electric parameters has been studied. Experimental results the amount of solar cell output parameters variations such as maximum output power, open circuit voltage, short circuit current, and fill factor in terms of temperature and light intensity shows. the most significant is the temperature dependence of the voltage which decreases with increasing t...

  14. Coefficients for Interrater Agreement.

    Science.gov (United States)

    Zegers, Frits E.

    1991-01-01

    The degree of agreement between two raters rating several objects for a single characteristic can be expressed through an association coefficient, such as the Pearson product-moment correlation. How to select an appropriate association coefficient, and the desirable properties and uses of a class of such coefficients--the Euclidean…

  15. Communication: Equilibrium rate coefficients from atomistic simulations: The O(3P) + NO(2Π) → O2(X3Σg−) + N(4S) reaction at temperatures relevant to the hypersonic flight regime

    International Nuclear Information System (INIS)

    The O(3P) + NO(2Π) → O2(X3Σg−) + N(4S) reaction is among the N- and O- involving reactions that dominate the energetics of the reactive air flow around spacecraft during hypersonic atmospheric re-entry. In this regime, the temperature in the bow shock typically ranges from 1000 to 20 000 K. The forward and reverse rate coefficients for this reaction derived directly from trajectory calculations over this range of temperature are reported in this letter. Results compare well with the established equilibrium constants for the same reaction from thermodynamic quantities derived from spectroscopy in the gas phase which paves the way for large-scale in silico investigations of equilibrium rates under extreme conditions

  16. Cell integrated multi-junction thermocouple array for solid oxide fuel cell temperature sensing: N+1 architecture

    Science.gov (United States)

    Ranaweera, Manoj; Kim, Jung-Sik

    2016-05-01

    Understanding the cell temperature distribution of solid oxide fuel cell (SOFC) stacks during normal operation has multifaceted advantages in performance and degradation studies. Present efforts on measuring temperature from operating SOFCs measure only the gas channel temperature and do not reveal the cell level temperature distribution, which is more important for understanding a cell's performance and its temperature-related degradation. The authors propose a cell-integrated, multi-junction thermocouple array for in-situ cell surface temperature monitoring of an operational SOFC. The proposed thermocouple array requires far fewer numbers of thermoelements than that required by sets of thermocouples for the same number of temperature sensing points. Hence, the proposed array causes lower disturbance to cell performance than thermocouples. The thermoelement array was sputter deposited on the cathode of a commercial SOFC using alumel (Ni:Al:Mn:Si - 95:2:2:1 by wt.) and chromel (Ni:Cr - 90:10 by wt.). The thermocouple array was tested in a furnace over the entire operating temperature range of a typical SOFC. The individual sensing points of the array were shown to measure temperature independently from each other with equivalent accuracy to a thermocouple. Thus, the concept of multi-junction thermocouples is experimentally validated and its stability on a porous SOFC cathode is confirmed.

  17. Low temperature rate coefficients for the reactions of 1CH2 with reactive and non-reactive species, and the implications for Titan's atmosphere

    Science.gov (United States)

    Douglas, Kevin; Slater, Eloise; Blitz, Mark; Plane, John; Heard, Dwayne; Seakins, Paul

    2016-04-01

    The Cassini-Huygens mission to Titan revealed unexpectedly large amounts of benzene in the troposphere, and confirmed the absence of a global ethane ocean as predicted by photochemical models of methane conversion over the lifetime of the solar system. An important chemical intermediate in both the production and loss of benzene and ethane is the first electronically excited state of methylene, 1CH2. For example, at room temperature an important reaction of 1CH2 is with acetylene (R1a), leading to the formation of propargyl (C3H3)[1]. The subsequent recombination of propargyl radicals is the major suggested route to benzene in Titan's atmosphere (R2)[2]. In addition to reaction of 1CH2 leading to products, there is also competition between inelastic electronic relaxation to form the ground triplet state 3CH2 (R1b). This ground state 3CH2 has a markedly different reactivity to the singlet, reacting primarily with methyl radicals (CH3) to form ethene (R3). As methyl radical recombination is the primary route to ethane (R4)[3], reactions of 1CH2 will also heavily influence the ethane budget on Titan. 1CH2 + C2H2 → C3H3 + H (R1a) 1CH2 + C2H2 → 3CH2 + C2H2 (R1b) C3H3 + C3H3 → C6H6 (R2) 3CH2 + CH3 → C2H4 + H (R3) CH3 + CH3 (+ M) → C2H6 (R4) Thus this competition between chemical reaction and electronic relaxation in the reactions of 1CH2 with H2, CH4, C2H4, and C2H6 will play an important role in determining the benzene and ethane budgets on Titan. Despite this there are no measurements of any rate constants for 1CH2 at temperatures relevant to Titan's atmosphere (60 - 170 K). Using a pulsed Laval nozzle apparatus coupled with pulsed laser photolysis laser-induced fluorescence, the low temperature reaction kinetics for the removal of 1CH2 with nitrogen, hydrogen, methane, ethane, ethene, acetylene, and oxygen, have been studied. The results revealed an increase in the removal rate of 1CH2 at temperatures below 200 K, with a sharp increase of around a factor of

  18. Apparatus for determination of vapor pressures at ambient temperatures employing a Knudsen effusion cell and quartz crystal microbalance

    International Nuclear Information System (INIS)

    We describe an apparatus for the measurement of vapor pressures of solids or liquids at ambient temperatures (260 K −2–10−6 Torr (1–10−4 Pa), but capable of being extended to lower pressures by at least an order of magnitude. It employs a Knudsen cell to produce an effusive molecular beam, only a small fraction of which is deposited on a cooled (225 K) quartz crystal microbalance (QCM). Vapor pressure values are derived from the mass gain rate determined by the QCM, Knudsen cell temperature, and fixed geometric factors. The accuracy and precision of the measurements are improved by locating the apparatus within an ultrahigh vacuum chamber (base pressure −9 Torr) with high pumping speed (2000 l s−1). A beam flag is used to interrupt the beam and allow for the subtraction of signal caused by the deposition of background molecules. The temperatures of both the microbalance and Knudsen cell are controlled to ±0.2 K using thermoelectric heaters/coolers. Measurements of the vapor pressure of benzoic acid, used as a primary reference material, agreed with literature reports over the entire temperature range to within the expected experimental uncertainty. In addition, the vapor pressure curves as a function of temperature (∼270–340 K) were determined for four isomers of dinitrotoluene (DNT). These curves can be readily expressed using the Clausius–Clapeyron relationship: log 10 P(Torr) = a - b/T(K), where a and b coefficients are listed below. Also listed is the heat of sublimation derived from these data. (Uncertainties are quoted as 2σ.)

  19. 蓝宝石光纤温度传感器K值标定系统%Calibration System of Sapphire-fiber Temperature Sensor's Coefficient K

    Institute of Scientific and Technical Information of China (English)

    王晓明; 郝晓剑; 周汉昌

    2012-01-01

    标定了一种镀制氧化锆陶瓷薄膜的蓝宝石光纤黑体腔温度传感器.标定系统用氢氧焰枪作为热源,以Modline3红外测温仪作为标准传感器,采用数据采集卡(PCI20612)对被校准传感器和Modline3的输出信号同步采集,通过比较法得到K值.实验验证了该方案的可行性,测得K值为98.578×106(V·m2/W),并得到该传感器温度-电压曲线,系统简单,方便,具有一定实用价值.%A kind of sapphire fiber blackbody cavity temperature sensor which was sprayed by ZrO2 film was calibrated. In this measruement system, hydrogen-oxygen gas flame welding machine was used as heat, Modline 3 infrared themometer was the standard sensor,data acquisition card(PCI20612) collected both of output of the calibrated sensor and Modline3. K was obstained by comparison. Experiments demonstrate the feasibility of this program,the results show K is 98. 578 x 10 ( V · m /W) ,and the T-V curve is presented. The calibration system is convenience and practical.

  20. Transport coefficients of heavy baryons

    Science.gov (United States)

    Tolos, Laura; Torres-Rincon, Juan M.; Das, Santosh K.

    2016-08-01

    We compute the transport coefficients (drag and momentum diffusion) of the low-lying heavy baryons Λc and Λb in a medium of light mesons formed at the later stages of high-energy heavy-ion collisions. We employ the Fokker-Planck approach to obtain the transport coefficients from unitarized baryon-meson interactions based on effective field theories that respect chiral and heavy-quark symmetries. We provide the transport coefficients as a function of temperature and heavy-baryon momentum, and analyze the applicability of certain nonrelativistic estimates. Moreover we compare our outcome for the spatial diffusion coefficient to the one coming from the solution of the Boltzmann-Uehling-Uhlenbeck transport equation, and we find a very good agreement between both calculations. The transport coefficients for Λc and Λb in a thermal bath will be used in a subsequent publication as input in a Langevin evolution code for the generation and propagation of heavy particles in heavy-ion collisions at LHC and RHIC energies.

  1. Dynamic Model of the High Temperature Proton Exchange Membrane Fuel Cell Stack Temperature

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen

    2009-01-01

    consists of a prototype cathode air cooled 30 cell HTPEM fuel cell stack developed at the Institute of Energy Technology at Aalborg University. This fuel cell stack uses PEMEAS Celtec P-1000 membranes and runs on pure hydrogen in a dead-end anode configuration with a purge valve. The cooling of the stack...

  2. Temperature induced transformation of teleost (Pimelodus maculatus) epidermal cells.

    Science.gov (United States)

    Ferri, S

    1982-01-01

    Superficial epidermal cells of the teleost Pimelodus maculatus show modifications after heat exposure (36 degrees C) for 3 days. Heat treatment affects the arrangement of cytoplasmic filaments resulting in the disappearance of the microridges. The fish maintained at 36 degrees C during 3 days show modifications in the cytoplasmic organization of their superficial epidermal cells. The most conspicuous alterations are: apparition of lysosomes (including autolysosomes), hypertrophy of the GOLGI complexes, disappearance of the RER, and modifications in the nuclear envelope. Epidermal cells maintained at 36 degrees C for 10 days are transformed into horny-like cells. The differences and resemblances with keratinized cells of terrestrial vertebrates are described and discussed. PMID:6891352

  3. The apparent diffusion coefficient of a primary lesion correlates with local failure of head and neck squamous cell carcinoma treated with radiotherapy. President award proceedings

    International Nuclear Information System (INIS)

    We prospectively investigated whether the value of the apparent diffusion coefficient (ADC) of a primary lesion prior to treatment correlated with local failure of head and neck squamous cell carcinoma (HNSCC) following radiotherapy. In 17 patients who underwent radiotherapy for primary HNSCC, we compared variables considered to affect local failure, including parameters related to magnetic resonance (MR) imaging, such as ADC and its alteration ratio, between cases of local failure and controls and analyzed survival among those patients in whom the variables differed or demonstrated association with local failure. We also retrospectively analyzed variables in a validation study of 40 patients. In the prospective study, pretreatment values of ADChigh (calculated with b-values of 300, 500, 750, and 1000 s/mm2) alone showed significant association with local failure (P=0.0186). In the validation study, pretreatment values of tumor volume (P=0.0217) and ADChigh (P=0.0001) were significantly associated with local failure. Pretreatment ADChigh was superior to pretreatment tumor volume regarding association with local failure. These results suggest that pretreatment values of both ADC obtained using high b-values and tumor volume correlate with local failure of HNSCC treated with radiotherapy. (author)

  4. High Temperature Electrolysis using Electrode-Supported Cells

    International Nuclear Information System (INIS)

    An experimental study is under way to assess the performance of electrode-supported solid-oxide cells operating in the steam electrolysis mode for hydrogen production. The cells currently under study were developed primarily for the fuel cell mode of operation. Results presented in this paper were obtained from single cells, with an active area of 16 cm2 per cell. The electrolysis cells are electrode-supported, with yttria-stabilized zirconia (YSZ) electrolytes (∼10 (micro)m thick), nickel-YSZ steam/hydrogen electrodes (∼1400 (micro)m thick), and manganite (LSM) air-side electrodes (∼90 (micro)m thick). The purpose of the present study was to document and compare the performance and degradation rates of these cells in the fuel cell mode and in the electrolysis mode under various operating conditions. Initial performance was documented through a series of DC potential sweeps and AC impedance spectroscopy measurements. Degradation was determined through long-duration testing, first in the fuel cell mode, then in the electrolysis mode over more than 500 hours of operation. Results indicate accelerated degradation rates in the electrolysis mode compared to the fuel cell mode, possibly due to electrode delamination. The paper also includes details of the single-cell test apparatus developed specifically for these experiments.

  5. High Temperature Electrolysis using Electrode-Supported Cells

    Energy Technology Data Exchange (ETDEWEB)

    J. E. O' Brien; C. M. Stoots

    2010-07-01

    An experimental study is under way to assess the performance of electrode-supported solid-oxide cells operating in the steam electrolysis mode for hydrogen production. The cells currently under study were developed primarily for the fuel cell mode of operation. Results presented in this paper were obtained from single cells, with an active area of 16 cm2 per cell. The electrolysis cells are electrode-supported, with yttria-stabilized zirconia (YSZ) electrolytes (~10 µm thick), nickel-YSZ steam/hydrogen electrodes (~1400 µm thick), and manganite (LSM) air-side electrodes (~90 µm thick). The purpose of the present study was to document and compare the performance and degradation rates of these cells in the fuel cell mode and in the electrolysis mode under various operating conditions. Initial performance was documented through a series of DC potential sweeps and AC impedance spectroscopy measurements. Degradation was determined through long-duration testing, first in the fuel cell mode, then in the electrolysis mode over more than 500 hours of operation. Results indicate accelerated degradation rates in the electrolysis mode compared to the fuel cell mode, possibly due to electrode delamination. The paper also includes details of the single-cell test apparatus developed specifically for these experiments.

  6. Mutual diffusion coefficients in systems containing the nickel ion

    Science.gov (United States)

    Ribeiro, Ana C. F.; Veríssimo, Luis V. M. M.; Gomes, Joselaine C. S.; Santos, Cecilia I. A. V.; Barros, Marisa C. F.; Lobo, Victor M. M.; Sobral, Abílio J. F. N.; Esteso, Miguel A.; Leaist, Derek G.

    2013-04-01

    Mutual diffusion coefficients of nickel chloride in water have been measured at 293.15 K and 303.15 K and at concentrations between 0.020 mol dm-3 and 0.100 mol dm-3, using a conductimetric cell. The experimental mutual diffusion coefficients are discussed on the basis of the Onsager-Fuoss model. The equivalent conductances at infinitesimal concentration of the nickel ion in these solutions at those temperatures have been estimated using these results. In addition, from these data, we have estimated some transport and structural parameters, such as limiting diffusion coefficient, ionic conductance at infinitesimal concentration, hydrodynamic radii and activation energy, contributing this way to a better understanding of the structure of these systems and of their thermodynamic behavior in aqueous solution at different concentrations.

  7. Determining intracellular temperature at single-cell levelby a novel thermocouple method

    Institute of Scientific and Technical Information of China (English)

    Changling Wang; Ruizhi Xu; Wenj uan Tian; Xiaoli Jiang; Zhengyu Cui; Meng Wang; Huaming Sun; Kun Fang; Ning Gu

    2011-01-01

    Dear Editor,Living cells can change their intramembranous temperature during cell activities such as division,gene expression,enzyme reaction,and metabolism [1,2].Moreover,under external stimuli,such as drugs or other signals,cells may quickly change their metabolic activities,leading to acute variation of intracellular temperatures from the normal state [3,4].However,such temperature change inside cells is usually at a small scale and is of transient nature due to the thermo-influence by the extracellular environment,rendering it rather difficult to measure using the conventional temperature detection methods.Thus,a more precise and faster-response thermometer is needed to measure single-cell temperature changes in real time,which may constitute a new layer of cellular information for studies of cellular signaling,and even clinical diagnosis and therapy.

  8. Enhancing photovoltaic efficiency through radiative cooling of solar cells below ambient temperature

    Science.gov (United States)

    Safi, Taqiyyah; Munday, Jeremy

    Sunlight heats up solar cells and the resulting elevated solar cell temperature adversely effects the photovoltaic efficiency and the reliability of the cell. Currently, a variety of active and passive cooling strategies are used to lower the operating temperature of the solar cell. Passive radiative cooling requires no energy input, and is ideal for solar cells; however, previously demonstrated devices still operate above the ambient, leading to a lower efficiency as compared to the ideal Shockley-Queisser limit, which is defined for a cell in contact with an ideal heat sink at ambient temperature (300 K). In this talk, we will describe the use of radiative cooling techniques to lower the cell temperature below the ambient temperature. We show that by combining specifically designed radiative cooling structures with solar cells, efficiencies higher than the limiting efficiency achievable at 300 K can be obtained for solar cells in both terrestrial and extraterrestrial environments. We show that these structures yield an efficiency 0.87% higher than a typical PV module at operating temperatures in a terrestrial application. We also demonstrate an efficiency advantage of 0.4-2.6% for cells in an extraterrestrial environment in near-earth orbit.

  9. Damage in Escherichia coli cells treated with a combination of high hydrostatic pressure and subzero temperature.

    Science.gov (United States)

    Moussa, Marwen; Perrier-Cornet, Jean-Marie; Gervais, Patrick

    2007-10-01

    The relationship between membrane permeability, changes in ultrastructure, and inactivation in Escherichia coli strain K-12TG1 cells subjected to high hydrostatic pressure treatment at room and subzero temperatures was studied. Propidium iodide staining performed before and after pressure treatment made it possible to distinguish between reversible and irreversible pressure-mediated cell membrane permeabilization. Changes in cell ultrastructure were studied using transmission electron microscopy (TEM), which showed noticeable condensation of nucleoids and aggregation of cytosolic proteins in cells fixed after decompression. A novel technique used to mix fixation reagents with the cell suspension in situ under high hydrostatic pressure (HHP) and subzero-temperature conditions made it possible to show the partial reversibility of pressure-induced nucleoid condensation. However, based on visual examination of TEM micrographs, protein aggregation did not seem to be reversible. Reversible cell membrane permeabilization was noticeable, particularly for HHP treatments at subzero temperature. A correlation between membrane permeabilization and cell inactivation was established, suggesting different mechanisms at room and subzero temperatures. We propose that the inactivation of E. coli cells under combined HHP and subzero temperature occurs mainly during their transiently permeabilized state, whereas HHP inactivation at room temperature is related to a balance of transient and permanent permeabilization. The correlation between TEM results and cell inactivation was not absolute. Further work is required to elucidate the effects of pressure-induced damage on nucleoids and proteins during cell inactivation. PMID:17766454

  10. Photorespiration and temperature dependence of oxygen evolution in tomato plants monitored by open photoacoustic cell technique

    Science.gov (United States)

    Vargas-Luna, M.; Madueño, L.; Gutiérrez-Juárez, G.; Bernal-Alvarado, J.; Sosa, M.; González-Solís, J. L.; Sánchez-Rocha, S.; Olalde-Portugal, V.; Alvarado-Gil, J. J.; Campos, P.

    2003-01-01

    The open photoacoustic cell was used to monitor the evolution rate of oxygen from tomato leaves. Estimates of the relative amount of released oxygen in vivo and in situ conditions as influenced by ambient temperature are being presented. Photorespiration phenomenon is shown to dominate above a critical temperature. The evolution of this critical point is analyzed as a function of the environmental temperature.

  11. Moissanite-anvil cells for the electrical transport measurements at low temperatures

    Science.gov (United States)

    Yomo, Shusuke; Tozer, Stanley W.

    2010-03-01

    We have successfully measured the Hall effect of a single crystal of a high temperature superconductor La2-xSrxCuO4 in moissanite-anvil high pressure cells. A pressure cell with new Zylon-gasket and wiring arrangement survived under pressure up to at least 5 GPa. Pressure which was clamped at room temperature increased with lowering the temperature down to below 60 K by a factor of 1.3-1.4.

  12. Moissanite-anvil cells for the electrical transport measurements at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Yomo, Shusuke [School of Biological Science and Engineering, Tokai University, Minami-ku, Sapporo 005-8601 (Japan); Tozer, Stanley W, E-mail: yomo@tokai-u.j [National High Magnetic Field Laboratory, Tallahassee, FL 32310-3706 (United States)

    2010-03-01

    We have successfully measured the Hall effect of a single crystal of a high temperature superconductor La{sub 2-x}Sr{sub x}CuO{sub 4} in moissanite-anvil high pressure cells. A pressure cell with new Zylon-gasket and wiring arrangement survived under pressure up to at least 5 GPa. Pressure which was clamped at room temperature increased with lowering the temperature down to below 60 K by a factor of 1.3-1.4.

  13. Moissanite-anvil cells for the electrical transport measurements at low temperatures

    International Nuclear Information System (INIS)

    We have successfully measured the Hall effect of a single crystal of a high temperature superconductor La2-xSrxCuO4 in moissanite-anvil high pressure cells. A pressure cell with new Zylon-gasket and wiring arrangement survived under pressure up to at least 5 GPa. Pressure which was clamped at room temperature increased with lowering the temperature down to below 60 K by a factor of 1.3-1.4.

  14. High Temperature Water Electrolysis Using Metal Supported Solid Oxide Electrolyzer Cells (SOEC)

    OpenAIRE

    Schiller, Günter; Ansar, Asif Syed; Patz, Olaf

    2010-01-01

    Metal supported cells as developed at DLR for use as solid oxide fuel cells by applying plasma deposition technologies were investigated in operation of high temperature steam electrolysis. The cells consisted of a porous ferritic steel support, a diffusion barrier layer, a Ni/YSZ fuel electrode, a YSZ electrolyte and a LSCF oxygen electrode. During fuel cell and electrolysis operation the cells were electrochemically characterized by means of i-V characteristics and electrochemical impedance...

  15. Convective cells of internal gravity waves in the earth's atmosphere with finite temperature gradient

    Directory of Open Access Journals (Sweden)

    O. Onishchenko

    2013-03-01

    Full Text Available In this paper, we have investigated vortex structures (e.g. convective cells of internal gravity waves (IGWs in the earth's atmosphere with a finite vertical temperature gradient. A closed system of nonlinear equations for these waves and the condition for existence of solitary convective cells are obtained. In the atmosphere layers where the temperature decreases with height, the presence of IGW convective cells is shown. The typical parameters of such structures in the earth's atmosphere are discussed.

  16. H2, He, and CO2 line-broadening coefficients, pressure shifts and temperature-dependence exponents for the HITRAN database. Part 1: SO2, NH3, HF, HCl, OCS and C2H2

    Science.gov (United States)

    Wilzewski, Jonas S.; Gordon, Iouli E.; Kochanov, Roman V.; Hill, Christian; Rothman, Laurence S.

    2016-01-01

    To increase the potential for use of the HITRAN database in astronomy, experimental and theoretical line-broadening coefficients, line shifts and temperature-dependence exponents of molecules of planetary interest broadened by H2, He, and CO2 have been assembled from available peer-reviewed sources. The collected data were used to create semi-empirical models so that every HITRAN line of the studied molecules has corresponding parameters. Since H2 and He are major constituents in the atmospheres of gas giants, and CO2 predominates in atmospheres of some rocky planets with volcanic activity, these spectroscopic data are important for remote sensing studies of planetary atmospheres. In this paper we make the first step in assembling complete sets of these parameters, thereby creating datasets for SO2, NH3, HF, HCl, OCS and C2H2.

  17. Design and Control of High Temperature PEM Fuel Cell System

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl

    often during a normal driving cycle. The combination of batteries and super capacitors together with fuel cells can improve the system performance, lifetime and cost. Simple systems can be designed where the fuel cells and batteries are directly connected, but the introduction of power electronics can...

  18. Degradation in Solid Oxide Cells During High Temperature Electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Manohar Sohal

    2009-05-01

    Idaho National Laboratory has an ongoing project to generate hydrogen from steam using solid oxide electrolysis cells. One goal of that project is to address the technical and degradation issues associated with solid oxide electrolysis cells. This report covers a variety of these degradation issues, which were discussed during a workshop on “Degradation in Solid Oxide Electrolysis Cells and Strategies for its Mitigation,” held in Phoenix, AZ on October 27, 2008. Three major degradation issues related to solid oxide electrolysis cells discussed at the workshop are: • Delamination of O2-electrode and bond layer on steam/O2-electrode side • Contaminants (Ni, Cr, Si, etc.) on reaction sites (triple-phase boundary) • Loss of electrical/ionic conductivity of electrolyte. This list is not all inclusive, but the workshop summary can be useful in providing a direction for future research related to the degradation of solid oxide electrolysis cells.

  19. Biomedical Applications of Low Temperature Atmospheric Pressure Plasmas to Cancerous Cell Treatment and Tooth Bleaching

    Science.gov (United States)

    Lee, Jae Koo; Kim, Myoung Soo; Byun, June Ho; Kim, Kyong Tai; Kim, Gyoo Cheon; Park, Gan Young

    2011-08-01

    Low temperature atmospheric pressure plasmas have attracted great interests and they have been widely applied to biomedical applications to interact with living tissues, cells, and bacteria due to their non-thermal property. This paper reviews the biomedical applications of low temperature atmospheric pressure plasmas to cancerous cell treatment and tooth bleaching. Gold nanoparticles conjugated with cancer-specific antibodies have been introduced to cancerous cells to enhance selective killing of cells, and the mechanism of cell apoptosis induced by plasma has been investigated. Tooth exposed to helium plasma jet with hydrogen peroxide has become brighter and the productions of hydroxyl radicals from hydrogen peroxide have been enhanced by plasma exposure.

  20. Diffusion Coefficients of Fluorinated Surfactants in Water:

    OpenAIRE

    Pereira, Luís A.M.; Martins, Luís F. G.; Ascenso, José R.; Morgado, Pedro; Ramalho, João P. P.; Filipe, Eduardo J. M.

    2014-01-01

    Intradiffusion coefficients of 2,2,2-trifluoroethanol in water have been measured by the pulsed field gradient (PFG)-NMR spin−echo technique as a function of temperature and composition on the dilute alcohol region. The measurements extend the range of compositions already studied in the literature and, for the first time, include the study of the temperature dependence. At the same time, intradiffusion coefficients of 2,2,2-trifluoroethanol, 2,2,3,3,3-pentafluoropropan-1-ol, ...

  1. High Temperature Solid Oxide Fuel Cell Generator Development

    Energy Technology Data Exchange (ETDEWEB)

    Joseph F. Pierre

    2006-08-21

    Work performed during the period February 21, 2006 through August 21, 2006 is summarized herein. During this period, efforts were focused on 5 kWe bundle testing, development of on-cell reformation, the conceptual design of an advanced module, and the development of a manufacturing roadmap for cells and bundles. A 5 kWe SOFC system was built and delivered to the Pennsylvania State University; fabrication of a second 5 kWe SOFC for delivery to Montana State University was initiated. Cell testing and microstructural analysis in support of these efforts was also conducted.

  2. Real Time Monitoring of Temperature of a Micro Proton Exchange Membrane Fuel Cell

    Directory of Open Access Journals (Sweden)

    Chih-Wei Chuang

    2009-03-01

    Full Text Available Silicon micro-hole arrays (Si-MHA were fabricated as a gas diffusion layer (GDL in a micro fuel cell using the micro-electro-mechanical-systems (MEMS fabrication technique. The resistance temperature detector (RTD sensor was integrated with the GDL on a bipolar plate to measure the temperature inside the fuel cell. Experimental results demonstrate that temperature was generally linearly related to resistance and that accuracy and sensitivity were within 0.5 °C and 1.68×10-3/°C, respectively. The best experimental performance was 9.37 mW/cm2 at an H2/O2 dry gas flow rate of 30/30 SCCM. Fuel cell temperature during operation was 27 °C, as measured using thermocouples in contact with the backside of the electrode. Fuel cell operating temperature measured in situ was 30.5 °C.

  3. Real time monitoring of temperature of a micro proton exchange membrane fuel cell.

    Science.gov (United States)

    Lee, Chi-Yuan; Lee, Shuo-Jen; Hu, Yuh-Chung; Shih, Wen-Pin; Fan, Wei-Yuan; Chuang, Chih-Wei

    2009-01-01

    Silicon micro-hole arrays (Si-MHA) were fabricated as a gas diffusion layer (GDL) in a micro fuel cell using the micro-electro-mechanical-systems (MEMS) fabrication technique. The resistance temperature detector (RTD) sensor was integrated with the GDL on a bipolar plate to measure the temperature inside the fuel cell. Experimental results demonstrate that temperature was generally linearly related to resistance and that accuracy and sensitivity were within 0.5 °C and 1.68×10(-3)/°C, respectively. The best experimental performance was 9.37 mW/cm(2) at an H(2)/O(2) dry gas flow rate of 30/30 SCCM. Fuel cell temperature during operation was 27 °C, as measured using thermocouples in contact with the backside of the electrode. Fuel cell operating temperature measured in situ was 30.5 °C. PMID:22573963

  4. FEM simulations and experimental studies of the temperature field in a large diamond crystal growth cell

    Institute of Scientific and Technical Information of China (English)

    Li Zhan-Chang; Jia Xiao-Peng; Huang Guo-Feng; Hu Mei-Hua; Li Yong; Yan Bing-Min; Ma Hong-An

    2013-01-01

    We investigate the temperature field variation in the growth region of a diamond crystal in a sealed cell during the whole process of crystal growth by using the temperature gradient method (TGM) at high pressure and high temperature (HPHT).We employ both the finite element method (FEM) and in situ experiments.Simulation results show that the temperature in the center area of the growth cell continues to decrease during the process of large diamond crystal growth.These results are in good agreement with our experimental data,which demonstrates that the finite element model can successfully predict the temperature field variations in the growth cell.The FEM simulation will be useful to grow larger high-quality diamond crystal by using the TGM.Furthermore,this method will be helpful in designing better cells and improving the growth process of gem-quality diamond crystal.

  5. FEM simulations and experimental studies of the temperature field in a large diamond crystal growth cell

    International Nuclear Information System (INIS)

    We investigate the temperature field variation in the growth region of a diamond crystal in a sealed cell during the whole process of crystal growth by using the temperature gradient method (TGM) at high pressure and high temperature (HPHT). We employ both the finite element method (FEM) and in situ experiments. Simulation results show that the temperature in the center area of the growth cell continues to decrease during the process of large diamond crystal growth. These results are in good agreement with our experimental data, which demonstrates that the finite element model can successfully predict the temperature field variations in the growth cell. The FEM simulation will be useful to grow larger high-quality diamond crystal by using the TGM. Furthermore, this method will be helpful in designing better cells and improving the growth process of gem-quality diamond crystal. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  6. Temperature propagation in prismatic lithium-ion-cells after short term thermal stress

    Science.gov (United States)

    Bohn, Pamina; Liebig, Gerd; Komsiyska, Lidiya; Wittstock, Gunther

    2016-05-01

    In this paper a 3D model based on the thermal material characteristics of an automotive prismatic Li-NiMnCoO2 (NMC) cell was created in COMSOL Multiphysics® in order to simulate the temperature propagation in the cell during short term thermal stress. The thermal characteristics of the battery components were experimentally determined via laser flash analysis (LFA) and differential scanning calorimetry (DSC) and used as an input parameter for the models. In order to validate the modelling approach, an experimental setup was built to measure the temperature propagation during thermal stresses within a dummy cell, equipped with temperature sensors. After validating, the model is used to describe the temperature propagation after a short-term temperature stress on automotive prismatic lithium-ion cells, simulating welding of the contact leads.

  7. High Temperature PEM Fuel Cells - Degradation and Durability

    DEFF Research Database (Denmark)

    Araya, Samuel Simon

    A harmonious mix of renewable and alternative energy sources, including fuel cells is necessary to mitigate problems associated with the current fossil fuel based energy system, like air pollution, Greenhouse Gas (GHG) emissions, and economic dependence on oil, and therefore on unstable areas of...... the globe. Fuel cells can harness the excess energy from other renewable sources, such as the big players in the renewable energy market, Photovoltaic (PV) panels and wind turbines, which inherently suffer from intermittency problems. The excess energy can be used to produce hydrogen from water or can...... be stored in liquid alcohols such as methanol, which can be sources of hydrogen for fuel cell applications. In addition, fuel cells unlike other technologies can use a variety of other fuels that can provide a source of hydrogen, such as biogas, methane, butane, etc. More fuel flexibility combined...

  8. High Temperature Solid Oxide Fuel Cell Generator Development

    Energy Technology Data Exchange (ETDEWEB)

    Joseph Pierre

    2007-09-30

    This report describes the results of the tubular SOFC development program from August 22, 1997 to September 30, 2007 under the Siemens/U.S. Department of Energy Cooperative Agreement. The technical areas discussed include cell manufacturing development, cell power enhancement, SOFC module and system cost reduction and technology advancement, and our field unit test program. Whereas significant progress has been made toward commercialization, significant effort remains to achieve our cost, performance and reliability targets for successful commercialization.

  9. High Temperature PEM Fuel Cells - Degradation and Durability

    OpenAIRE

    Araya, Samuel Simon

    2012-01-01

    A harmonious mix of renewable and alternative energy sources, including fuel cells is necessary to mitigate problems associated with the current fossil fuel based energy system, like air pollution, Greenhouse Gas (GHG) emissions, and economic dependence on oil, and therefore on unstable areas of the globe. Fuel cells can harness the excess energy from other renewable sources, such as the big players in the renewable energy market, Photovoltaic (PV) panels and wind turbines, which inherently s...

  10. Analysis of the CREOLE experiment on the reactivity temperature coefficient using the MCNP5 code with ENDF/B-VII and JEFF3.1 neutron cross section evaluations

    International Nuclear Information System (INIS)

    In the present work, we have analyzed the CREOLE experiment on the reactivity temperature coefficient (RTC) by using the MCNP code with the recently updated nuclear data evaluations. In this experiment performed in the EOLE critical facility located at CEA/Cadarache, the RTC has been measured in both UO2 and UO2-PuO2 PWR type lattices covering the whole temperature range from 20 deg. C to 300 deg. C. An accurate model of the EOLE reactor was developed by using the three-dimensional continuous energy code MCNP5. This Monte Carlo code guarantees a high level of fidelity in the description of the reactor core components at all temperatures taking into account their consequence on neutron cross sections data and all thermal expansion effects. In this case, the remaining discrepancy between calculation and experiment will be awarded mainly to uncertainties on nuclear data. The cross section libraries were generated by using NJOY-99.259 code with point-wise cross sections based on ENDF-BVII and JEFF3.1 evaluation files. The calculation-experiment discrepancies of the RTC were analyzed and the results have shown that the JEFF3.1 evaluation gives more consistent values than those obtained by ENDF-BVII. By using the JEFF3.1 evaluation, it may be pointed out that for UO2 clean lattices; the discrepancy is generally less than 0.17 pcm/ deg. C whereas for the UO2-PuO2 lattices it is less than 0,23 pcm/deg. C. These results confirm those previously published and show that the error on RTC in the MOX lattices case is greater than that obtained in the case of UOX clean lattices, particularly at room temperature range. (author)

  11. Conductivities and Seebeck coefficients of boron carbides: Softening bipolaron hopping

    Science.gov (United States)

    Aselage, T. L.; Emin, D.; McCready, S. S.

    2001-08-01

    The electrical conductivities and Seebeck coefficients of boron carbides B12+xC3-x with 0.06function of the composition x. This strong sensitivity to composition indicates that percolation effects, arising from boron carbides having carbon atoms in inequivalent locations, influence the conductivity at low temperature. With x holes per unit cell, boron carbides have very large Seebeck coefficients that depend only weakly on x. The magnitudes and temperature dependences of the Seebeck coefficients are consistent with large contributions from carrier-induced softening of local vibrations. Softening effects can be exceptionally large when singlet bipolarons are stabilized among degenerate electronic energy levels by their softening of symmetry-breaking vibrations: ``softening bipolarons.'' The boron carbide transport properties are generally consistent with those expected of softening bipolarons. Finally, two high-temperature effects are observed in the boron carbide conductivities. The conductivities of samples having high carrier densities, x~1, are suppressed above 700 K. This suppression can arise when the rapid hopping of nearby carriers disrupts the energy coincidence required for a carrier's hop. At even higher temperatures, a sharp increase in the boron carbide conductivities (σ~T4) suggests a radiation-induced excitation of mobile charge carriers.

  12. Temperature Gradients on the Cell Wall in the Critical Viscosity Experiment

    Science.gov (United States)

    Berg, Robert F.; Moldover, Michael R.

    1993-01-01

    Because of the diverging susceptibility delta rho/delta Tau near the liquid-vapor critical point, temperature gradients must be kept small to maintain adequate sample homogeneity. In our Science Requirements Document we paid particular attention to radial density gradients caused by equilibration of the xenon sample. Axial density gradients were addressed through the requirement that the cell's copper wall have a gradient less than 22 microK/m. This report re-examines the cell wall's temperature distribution in more detail by estimating all known significant contributions to temperature differences on the cell's wall.

  13. Temperature dependent estimator for load cells using an adaptive neuro-fuzzy inference system

    Energy Technology Data Exchange (ETDEWEB)

    Lee, K-C [Department of Automation Engineering, National Formosa University, Huwei, Yunlin 63208, Taiwan (China)

    2005-01-01

    Accurate weighting of pieces in various temperature environments for load cells is a key feature in many industrial applications. This paper proposes a method to achieve high-precision {+-}0.56/3000 grams for a load-cell-based weighting system by using ANFIS. ANFIS is used to model the relationship between the reading of load cells and the actual weight of samples considering temperature-varying effect and nonlinearity of the load cells. The model of the load-cell-based weighting system can accurately estimate the weight of test samples from the load cell reading. The proposed ANFIS-based method is convenient for use and can improve the precision of digital load cell measurement systems. Experiments demonstrate the validity and effectiveness of fuzzy neural networks for modeling of load cells and the results show that the proposed ANFIS-based method outperforms some existing methods in terms of modeling and prediction accuracy.

  14. A Direct DME High Temperature PEM Fuel Cell

    DEFF Research Database (Denmark)

    Vassiliev, Anton; Jensen, Jens Oluf; Li, Qingfeng;

    2012-01-01

    Dimethyl ether (DME) has been identified as an alternative to methanol for use in direct fuel cells. It combines the advantages of hydrogen in terms of pumpless fuel delivery and high energy density like methanol, but without the toxicity of the latter. The performance of a direct dimethyl ether...... fuel cell suffers greatly from the very low DME-water miscibility. To cope with the problem polybenzimidazole (PBI) based membrane electrode assemblies (MEAs) have been made and tested in a vapor fed system. PtRu on carbon has been used as anode catalyst and air at ambient pressure was used as oxidant...

  15. Estimation of optimal b-value sets for obtaining apparent diffusion coefficient free from perfusion in non-small cell lung cancer

    Science.gov (United States)

    Karki, Kishor; Hugo, Geoffrey D.; Ford, John C.; Olsen, Kathryn M.; Saraiya, Siddharth; Groves, Robert; Weiss, Elisabeth

    2015-10-01

    The purpose of this study was to determine optimal sets of b-values in diffusion-weighted MRI (DW-MRI) for obtaining monoexponential apparent diffusion coefficient (ADC) close to perfusion-insensitive intravoxel incoherent motion (IVIM) model ADC (ADCIVIM) in non-small cell lung cancer. Ten subjects had 40 DW-MRI scans before and during radiotherapy in a 1.5 T MRI scanner. Respiratory triggering was applied to the echo-planar DW-MRI with \\text{TR}≈ 4500 ms, TE  =  74 ms, eight b-values of 0-1000 μs μm-2, pixel size  =  1.98× 1.98 mm2, slice thickness  =  6 mm, interslice gap  =  1.2 mm, 7 axial slices and total acquisition time ≈6 min. One or more DW-MRI scans together covered the whole tumour volume. Monoexponential model ADC values using various b-value sets were compared to reference-standard ADCIVIM values using all eight b-values. Intra-scan coefficient of variation (CV) of active tumour volumes was computed to compare the relative noise in ADC maps. ADC values for one pre-treatment DW-MRI scan of each of the 10 subjects were computed using b-value pairs from DW-MRI images synthesized for b-values of 0-2000 μs μm-2 from the estimated IVIM parametric maps and corrupted by various Rician noise levels. The square root of mean of squared error percentage (RMSE) of the ADC value relative to the corresponding ADCIVIM for the tumour volume of the scan was computed. Monoexponential ADC values for the b-value sets of 250 and 1000; 250, 500 and 1000; 250, 650 and 1000; 250, 800 and 1000; and 250-1000 μs μm-2 were not significantly different from ADCIVIM values (p>0.05 , paired t-test). Mean error in ADC values for these sets relative to ADCIVIM were within 3.5%. Intra-scan CVs for these sets were comparable to that for ADCIVIM. The monoexponential ADC values for other sets—0-1000 50-1000 100-1000 500-1000 and 250 and 800 μs μm-2 were significantly different from the ADCIVIM values. From Rician noise simulation

  16. Temperature dependence of an abiotic glucose/air alkaline fuel cell

    Science.gov (United States)

    Orton, Dane; Scott, Daniel

    2015-11-01

    The temperature dependence of a previously developed glucose fuel cell is explored. This cell uses a small molecule dye mediator to transport oxidizable electrons from glucose to a carbon felt anode. This reaction is driven by an air breathing MnO2 cathode. This research investigates how the temperature of the system affects the power production of the fuel cell. Cell performance is observed using either methyl viologen, indigo carmine, trypan blue, or hydroquinone as a mediator at temperatures of 15, 19, 27, 32, 37, 42, and 49 °C. Cyclic voltammetry of the cell anode at the given temperatures with the individual dyes is also presented. The highest power production amongst all of the cells occurs at 32 °C. This occurs with the mediator indigo carmine or with the mediator methyl viologen. These sustained powers are 2.31 mW cm-2 and 2.39 mW cm-2, respectively. This is approximately a 350% increase for these cells compared to their power produced at room temperature. This dramatic increase is likely due to increased solubility of the mediator dye at higher temperatures.

  17. Temperature-responsive intelligent interfaces for biomolecular separation and cell sheet engineering.

    Science.gov (United States)

    Nagase, Kenichi; Kobayashi, Jun; Okano, Teruo

    2009-06-01

    Temperature-responsive intelligent surfaces, prepared by the modification of an interface with poly(N-isopropylacrylamide) and its derivatives, have been used for biomedical applications. Such surfaces exhibit temperature-responsive hydrophilic/hydrophobic alterations with external temperature changes, which, in turn, result in thermally modulated interactions with biomolecules and cells. In this review, we focus on the application of these intelligent surfaces to chromatographic separation and cell cultures. Chromatographic separations using several types of intelligent surfaces are mentioned briefly, and various effects related to the separation of bioactive compounds are discussed, including wettability, copolymer composition and graft polymer architecture. Similarly, we also summarize temperature-responsive cell culture substrates that allow the recovery of confluent cell monolayers as contiguous living cell sheets for tissue-engineering applications. The key factors in temperature-dependent cell adhesion/detachment control are discussed from the viewpoint of grafting temperature-responsive polymers, and new methodologies for effective cell sheet culturing and the construction of thick tissues are summarized. PMID:19324682

  18. The Randomized Dependence Coefficient

    OpenAIRE

    Lopez-Paz, David; Hennig, Philipp; Schölkopf, Bernhard

    2013-01-01

    We introduce the Randomized Dependence Coefficient (RDC), a measure of non-linear dependence between random variables of arbitrary dimension based on the Hirschfeld-Gebelein-R\\'enyi Maximum Correlation Coefficient. RDC is defined in terms of correlation of random non-linear copula projections; it is invariant with respect to marginal distribution transformations, has low computational cost and is easy to implement: just five lines of R code, included at the end of the paper.

  19. Durable Catalysts for High Temperature Proton Exchange Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Durability of proton exchange membrane fuel cells (PEMFCs) is recognized as one of the most important issues to be addressed before the commercialization. The failure mechanisms are not well understood, however, degradation of carbon supported noble metal catalysts is identified as a major failure...

  20. Low Temperature and Polyploidy Result in Larger Cell and Body Size in an Ectothermic Vertebrate.

    Science.gov (United States)

    Hermaniuk, Adam; Rybacki, Mariusz; Taylor, Jan R E

    2016-01-01

    Previous studies reported that low temperatures result in increases in both cell size and body size in ectotherms that may explain patterns of geographic variation of their body size across latitudinal ranges. Also, polyploidy showed the same effect on body size in invertebrates. In vertebrates, despite their having larger cells, no clear effect of polyploidy on body size has been found. This article presents the relationship between temperature, cell size, growth rate, and body size in diploid and polyploid hybridogenetic frog Pelophylax esculentus reared as tadpoles at 19° and 24°C. The size of cells was larger in both diploid and triploid tadpoles at 19°C, and triploids had larger cells at both temperatures. In diploid and triploid froglets, the temperature in which they developed as tadpoles did not affect the size of their cells, but triploids still had larger cells. Triploid tadpoles grew faster than diploids at 19°C and had larger body mass; there was no clear difference between ploidies in growth rate at 24°C. This indicates better adaptation of triploid tadpoles to cold environment. This is the first report on the increase of body mass of a polyploid vertebrate caused by low temperature, and we showed relationship between increase in cell size and increased body mass. The large body mass of triploids may provide a selective advantage, especially in colder environments, and this may explain the prevalence of triploids in the northern parts of the geographic range of P. esculentus. PMID:27082722

  1. The experimental investigation of linear expansion coefficient measurement of car fuel supplying cell parts%轿车供油单元零件线膨胀系数测定试验研究

    Institute of Scientific and Technical Information of China (English)

    麻文焱; 杨延俊; 潘发明

    2009-01-01

    详细研究了电阻应变计法测量材料线膨胀系数的原理,结合轿车供油单元零件线膨胀系数测定试验,具体阐述了试验步骤及方法.结果表明应用电阻应变计法测试材料线膨胀系数是一种既简单实用又经济的测试技术.%This article studies the principle of measuring coefficient of linear expansion by using resistance strain gauge and discusses the experimental steps and methods combining with the determination test of linear expansion coefficient of car fuel supply cell parts. The result shows it is a practical and economical testing technique to measure linear expansion coefficients of materials by resistance strain gauge.

  2. Fabrication and Characterizations of Materials and Components for Intermediate Temperature Fuel Cells and Water Electrolysers

    DEFF Research Database (Denmark)

    Jensen, Annemette Hindhede; Prag, Carsten Brorson; Li, Qingfeng;

    The worldwide development of fuel cells and electrolysers has so far almost exclusively addressed either the low temperature window (20-200 °C) or the high temperature window (600-1000 °C). This work concerns the development of key materials and components of a new generation of fuel cells and...... electrolysers for operation in the intermediate temperature range from 200 to 400 °C. The intermediate temperature interval is of importance for the use of renewable fuels. Furthermore electrode kinetics is significantly enhanced compared to when operating at low temperature. Thus non-noble metal catalysts...... might be used. One of the key materials in the fuel cell and electrolyser systems is the electrolyte. Proton conducting materials such as cesium hydrogen phosphates, zirconium hydrogen phosphates and tin pyrophosphates have been investigated by others and have shown interesting potential....

  3. Durability Issues of High Temperature Proton Exchange Membrane Fuel Cells Based on Acid Doped Polybenzimidazole Membranes

    DEFF Research Database (Denmark)

    To achieve high temperature operation of proton exchange membrane fuel cells (PEMFC), preferably under ambient pressure, phosphoric acid doped polybenzimidazole (PBI) membrane represents an effective approach, which in recent years has motivated extensive research activities with great progress. As...

  4. Experimental Investigation of the Integral 2π Emissivity. Electrical Conductivity and Thermal Conductivity Coefficient for a Number of High-Melting Metals in the Temperature Range 1300-3000°K

    International Nuclear Information System (INIS)

    The high-melting metals molybdenum, tantalum, niobium and others serve as a basis for modern vapour-tight structural materials in new technical fields, and in particular for MHD generators. They are becoming increasingly widely used both in the pure form and in the form of alloys and chemical compounds. The investigation of their thermophysical properties, in particular the thermal conductivity coefficient, the specific electric resistance and the integral emissivity, is a very pressing problem, important both from the strictly applied and from the theoretical point of view. In the present paper, the experimental methods of studying these characteristics are based on electron heating. This has made it possible to experiment with samples of simple geometry (short cylinders, 10-12 mm diam.), and in practice to remove restrictions on the temperature levels attainable. All the properties concerned are studied together on two experimental rigs of original design, and measurements may be made on one and the same sample. The error of the measurements does not exceed ± 1 to 1.5 % for electrical conductivity, ± 6 to 8% for the integral 2π emissivity, and ± 10 to 12% for the thermal conductivity coefficent. The paper investigates molybdenum (poly- and monocrystalline), tantalum, niobium and hafnium iodide. The data obtained have made it possible to gain a more precise idea of the accuracy of the Wiedemann-Franz- Lorentz relationship for this group of metals in the high temperature region. Data have been obtained for the first time for a number of temperature ranges for niobium, tantalum and hafnium. (author)

  5. Large low field magneto-resistance and temperature coefficient of resistance in La{sub 0.8}Ca{sub 0.2}MnO{sub 3} epitaxial thin film

    Energy Technology Data Exchange (ETDEWEB)

    Debnath, J.C., E-mail: jcd341@uowmail.edu.au; Strydom, A.M.

    2015-02-05

    Highlights: • A giant value of MR 73% and 57% for both the directions are obtained at 1.5 T applied field. • The values of TCR about 14.2% K{sup −1} and 11.5% K{sup −1} for both directions are obtained in a wide temperature range. • This film is potential in non-cooling and highly sensitive bolometric applications. • This epitaxial thin film is efficient for the application of novel electronic devices. - Abstract: An epitaxial La{sub 0.8}Ca{sub 0.2}MnO{sub 3}/LaAlO{sub 3} (LCMO/LAO) thin film was fabricated using the pulsed laser deposition (PLD) technique to evaluate the magnetoresistance (MR) and temperature coefficient of resistance (TCR). The LCMO film was about 200 nm in thickness and appeared to have a strong out-of-plane texture. A giant value of MR 73% and 57% for both the ab-plane and in the c-directions respectively are obtained at 1.5 T applied field. The values of TCR are about 14.2% K{sup −1} and 11.5% K{sup −1} for both the ab-plane and in the c-directions respectively in a wide temperature range. These results proved that La{sub 0.8}Ca{sub 0.2}MnO{sub 3}/LaAlO{sub 3} (LCMO/LAO) thin film is a promising candidate of perovskites for novel electronic applications.

  6. Influence of elevated body temperature on circulating immunoglobulin-secreting cells

    DEFF Research Database (Denmark)

    Kappel, M; Barington, T; Gyhrs, A; Pedersen, Bente Klarlund

    1995-01-01

    This work was designed to investigate the effect of in vivo hyperthermia in man on circulating immunoglobulin-secreting cells. Eight healthy male volunteers were immersed into a hot waterbath (WI) (water temperature 39.5 degrees C) for 2 h, whereby their body temperature rose to 39.5 degrees C. On...... another occasion they served as their own controls, being immersed into thermoneutral water (water temperature 34.5 degrees C) for 2 h. Blood samples were drawn before immersion, at body temperatures of 38, 39 and 39.5 degrees C, as well as 2 h after WI when their body temperatures were normalized. In the...

  7. Platinum redispersion on metal oxides in low temperature fuel cells

    DEFF Research Database (Denmark)

    Tripkovic, Vladimir; Cerri, Isotta; Nagami, Tetsuo; Bligaard, Thomas; Rossmeisl, Jan

    2013-01-01

    We have analyzed the aptitude of several metal oxide supports (TiO2, SnO2, NbO2, ZrO2, SiO2, Ta2O5 and Nb2O5) to redisperse platinum under electrochemical conditions pertinent to the Proton Exchange Membrane Fuel Cell (PEMFC) cathode. The redispersion on oxide supports in air has been studied in...

  8. Integration of Biomass Gasification with High Temperature Fuel Cells

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Karel; Hartman, Miloslav; Baxter, D.; Hunter, Ch.

    České Budějovice: Energy Consulting, 2003, s. 145-155. ISBN 80-239-1142-2. [International Conference of Central European Energy , Efficiency and Renewable Energy Sources CEEERES'03 /2./. Prague (CZ), 10.11.2003-11.11.2003] Institutional research plan: CEZ:AV0Z4072921 Keywords : biomass * gasification * fuel cells Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  9. Spatial and Temporal Measurements of Temperature and Cell Viability in Response to Nanoparticle Mediated Photothermal Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Whitney, Jon R [ORNL; Rodgers, Amanda [Virginia Polytechnic Institute and State University; Harvie, Erica [Virginia Polytechnic Institute and State University; Carswell, William [Virginia Polytechnic Institute and State University; Torti, Suzy [Wake Forest University, Winston-Salem; Puretzky, Alexander A [ORNL; Rouleau, Christopher M [ORNL; Geohegan, David B [ORNL; Rylander, Christopher [Virginia Polytechnic Institute and State University; Rylander, Nichole M [Virginia Polytechnic Institute and State University

    2012-01-01

    Aim: Nanoparticle enhanced photothermal therapy is a promising alternative to tumor resection. However, quantitative measurements of cellular response to these treatments are limited. This paper introduces a Bimodal Enhanced Analysis of Spatiotemporal Temperature (BEAST) algorithm to rapidly determine the viability of cancer cells in vitro following photothermal therapy alone or in combination with nanoparticles. Materials & Methods: To illustrate the capability of the BEAST viability algorithm, single wall carbon nanohorns were added to renal cancer (RENCA) cells in vitro and time-dependent spatial temperature maps measured with an infrared camera during laser therapy were correlated with post-treatment cell viability distribution maps obtained by cell-staining fluorescent microscopy. Conclusion: The BEAST viability algorithm accurately and rapidly determined the cell viability as function of time, space, and temperature.

  10. The use of Electrolyte Additives to Improve the High Temperature Resilience of Li-Ion Cells

    Science.gov (United States)

    Smart, Marshall C.; Lucht, B. L.; Ratnakumar, Bugga V.

    2007-01-01

    This viewgraph presentation reviews the use of electrolyte additves to improve the resillience of Lithium ion cells. The objective of this work is to identify lithium-ion electrolytes, which will lead to Li-ion cells with a wide operational temperature range (+60 to -60 C), and to develop Li-ion electrolytes which result in cells that display improved high temperature resilience. Significant improvement in the high temperature resilience of Li-ion cells containing these additives was observed, with the most dramatic benefit being displayed by addition of DMAc. When the electrochemical properties of the individual electrodes were analyzed, the degradation of the anode kinetics was slowed most dramatically by the incorporation of DMAc into the electrolytes. Whereas, the greatest retention in the cathode kinetics was observed in the cell containing the electrolyte with VC added.

  11. Climatology Applied To Architecture: An Experimental Investigation about Internal Temperatures Distribution at Two Test Cells

    Directory of Open Access Journals (Sweden)

    Grace Tibério Cardoso

    2016-04-01

    Full Text Available Data were analyzed en relative spatial distribution of the internal surface temperature (IST and internal air temperature or dry bulb (TBS, in two different test cells, for a typical experimental day under the influence of tropical mass. The main goal of this research is to provide guidelines to collect temperature data experimentally since there is not an appropriate standard to guide this methodological procedure in buildings. The data series of dry bulb temperature and internal surface temperatures were measured in a test cell with a green roof and the other with conventional ceramic roof by thermocouples installed at predetermined locations. The data of solar radiation and the main climatic variables were recorded by the automatic weather station at the Center of Science Engineering Applied to the Environment (CCEAMA, School of Engineering of São Carlos (EESC-USP. The results led to the conclusion that the distribution of the internal surface temperature is almost uniform in the two test cells, but in relation to the dry bulb temperature there is a small vertical temperature gradient in the conventional cell. This work will contribute significantly to future studies in the area of human comfort and environmental suitability of buildings

  12. BEHAVIOR OF CHO CELLS ON MODIFIED POLYPROPYLENE BY LOW TEMPERATURE AMMONIA PLASMA

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hong; YU Yaoting; PAN Jilun; XU Yuanping; ZHU Hesun

    2001-01-01

    The surface of polypropylene (PP) membrane was modified by low temperature plasma with ammonia. The effect of exposure time was investigated by means of contact angle measurement. The results show that low temperature ammonia plcsma treatment can enhance its hydrophilicity. Chinese hamster ovary (CHO) cells attachment on the modified membrane was enhanced and the growth rate on the membrane was faster than unmodified one.

  13. File list: NoD.Adl.20.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available NoD.Adl.20.AllAg.Temperature_sensitive_cells dm3 No description Adult Temperature s...ensitive cells http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/NoD.Adl.20.AllAg.Temperature_sensitive_cells.bed ...

  14. File list: NoD.Adl.10.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available NoD.Adl.10.AllAg.Temperature_sensitive_cells dm3 No description Adult Temperature s...ensitive cells http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/NoD.Adl.10.AllAg.Temperature_sensitive_cells.bed ...

  15. File list: InP.Adl.20.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Adl.20.AllAg.Temperature_sensitive_cells dm3 Input control Adult Temperature se...nsitive cells http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Adl.20.AllAg.Temperature_sensitive_cells.bed ...

  16. File list: InP.Adl.50.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Adl.50.AllAg.Temperature_sensitive_cells dm3 Input control Adult Temperature se...nsitive cells http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Adl.50.AllAg.Temperature_sensitive_cells.bed ...

  17. File list: NoD.Adl.50.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available NoD.Adl.50.AllAg.Temperature_sensitive_cells dm3 No description Adult Temperature s...ensitive cells http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/NoD.Adl.50.AllAg.Temperature_sensitive_cells.bed ...

  18. File list: InP.Adl.05.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Adl.05.AllAg.Temperature_sensitive_cells dm3 Input control Adult Temperature se...nsitive cells http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Adl.05.AllAg.Temperature_sensitive_cells.bed ...

  19. File list: InP.Adl.10.AllAg.Temperature_sensitive_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available InP.Adl.10.AllAg.Temperature_sensitive_cells dm3 Input control Adult Temperature se...nsitive cells http://dbarchive.biosciencedbc.jp/kyushu-u/dm3/assembled/InP.Adl.10.AllAg.Temperature_sensitive_cells.bed ...

  20. Sudden collapse of vacuoles in Saintpaulia sp. palisade cells induced by a rapid temperature decrease.

    Science.gov (United States)

    Kadohama, Noriaki; Goh, Tatsuaki; Ohnishi, Miwa; Fukaki, Hidehiro; Mimura, Tetsuro; Suzuki, Yoshihiro

    2013-01-01

    It is well known that saintpaulia leaf is damaged by the rapid temperature decrease when cold water is irrigated onto the leaf surface. We investigated this temperature sensitivity and the mechanisms of leaf damage in saintpaulia (Saintpaulia sp. cv. 'Iceberg') and other Gesneriaceae plants. Saintpaulia leaves were damaged and discolored when subjected to a rapid decrease in temperature, but not when the temperature was decreased gradually. Sensitivity to rapid temperature decrease increased within 10 to 20 min during pre-incubation at higher temperature. Injury was restricted to the palisade mesophyll cells, where there was an obvious change in the color of the chloroplasts. During a rapid temperature decrease, chlorophyll fluorescence monitored by a pulse amplitude modulated fluorometer diminished and did not recover even after rewarming to the initial temperature. Isolated chloroplasts were not directly affected by the rapid temperature decrease. Intracellular pH was monitored with a pH-dependent fluorescent dye. In palisade mesophyll cells damaged by rapid temperature decrease, the cytosolic pH decreased and the vacuolar membrane collapsed soon after a temperature decrease. In isolated chloroplasts, chlorophyll fluorescence declined when the pH of the medium was lowered. These results suggest that a rapid temperature decrease directly or indirectly affects the vacuolar membrane, resulting in a pH change in the cytosol that subsequently affects the chloroplasts in palisade mesophyll cells. We further confirmed that the same physiological damage occurs in other Gesneriaceae plants. These results strongly suggested that the vacuoles of palisade mesophyll cells collapsed during the initial phase of leaf injury. PMID:23451194

  1. Sudden collapse of vacuoles in Saintpaulia sp. palisade cells induced by a rapid temperature decrease.

    Directory of Open Access Journals (Sweden)

    Noriaki Kadohama

    Full Text Available It is well known that saintpaulia leaf is damaged by the rapid temperature decrease when cold water is irrigated onto the leaf surface. We investigated this temperature sensitivity and the mechanisms of leaf damage in saintpaulia (Saintpaulia sp. cv. 'Iceberg' and other Gesneriaceae plants. Saintpaulia leaves were damaged and discolored when subjected to a rapid decrease in temperature, but not when the temperature was decreased gradually. Sensitivity to rapid temperature decrease increased within 10 to 20 min during pre-incubation at higher temperature. Injury was restricted to the palisade mesophyll cells, where there was an obvious change in the color of the chloroplasts. During a rapid temperature decrease, chlorophyll fluorescence monitored by a pulse amplitude modulated fluorometer diminished and did not recover even after rewarming to the initial temperature. Isolated chloroplasts were not directly affected by the rapid temperature decrease. Intracellular pH was monitored with a pH-dependent fluorescent dye. In palisade mesophyll cells damaged by rapid temperature decrease, the cytosolic pH decreased and the vacuolar membrane collapsed soon after a temperature decrease. In isolated chloroplasts, chlorophyll fluorescence declined when the pH of the medium was lowered. These results suggest that a rapid temperature decrease directly or indirectly affects the vacuolar membrane, resulting in a pH change in the cytosol that subsequently affects the chloroplasts in palisade mesophyll cells. We further confirmed that the same physiological damage occurs in other Gesneriaceae plants. These results strongly suggested that the vacuoles of palisade mesophyll cells collapsed during the initial phase of leaf injury.

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

    DEFF Research Database (Denmark)

    Samson, Alfred Junio

    . High performance cathodes were obtained from strontium-doped lanthanum cobaltite (LSC) infiltrated - Ce0.9Gd0.1O1.95 (CGO) ionic conducting backbone. Systematic tuning of the CGO and LSC firing temperatures and LSC loading resulted in a cathode with low polarization resistance, Rp = 0.044 cm2 at 600......+delta/CGO 50 vol % composite cathode at 600degreeC. A 1-dimensional model has been developed in order to understand and predict the the performance of cathodes prepared by LSC infiltration. With the model, it was possible to extract an expression for the area specific resistance associated with oxygen...... surface exchange for the infiltrated LSC. The extracted values are significantly lower than literature values suggesting that the performance of LSC-infiltrated cathodes could not be explained by downscaled microstructure alone. A series of microstructural parameter variations are presented and discussed...

  3. Electrochemical characterization of a polybenzimidazole-based high temperature proton exchange membrane unit cell

    DEFF Research Database (Denmark)

    Jespersen, Jesper Lebæk; Schaltz, Erik; Kær, Søren Knudsen

    2009-01-01

    This work constitutes detailed EIS (Electrochemical Impedance Spectroscopy) measurements on a PBIbased HT-PEM unit cell. By means of EIS the fuel cell is characterized in several modes of operation by varying the current density, temperature and the stoichiometry of the reactant gases. Using...

  4. Simple electrolyzer model development for high-temperature electrolysis system analysis using solid oxide electrolysis cell

    International Nuclear Information System (INIS)

    An electrolyzer model for the analysis of a hydrogen production system using a solid oxide electrolysis cell has been developed, and the effects of principal parameters have been estimated via sensitivity studies based on the developed model. The main parameters considered were current density, area-specific resistance, temperature, pressure, molar fraction, and flow rates in the inlet and outlet. A simple model is also estimated for a high-temperature hydrogen production system that integrates the solid oxide electrolysis cell with a very high temperature reactor. (author)

  5. Simple Electrolyzer Model Development for High-Temperature Electrolysis System Analysis Using Solid Oxide Electrolysis Cell

    International Nuclear Information System (INIS)

    An electrolyzer model for the analysis of a hydrogen-production system using a solid oxide electrolysis cell (SOEC) has been developed, and the effects for principal parameters have been estimated by sensitivity studies based on the developed model. The main parameters considered are current density, area specific resistance, temperature, pressure, and molar fraction and flow rates in the inlet and outlet. Finally, a simple model for a high-temperature hydrogen-production system using the solid oxide electrolysis cell integrated with very high temperature reactors is estimated.

  6. Enhancing Protein Expression in HEK-293 Cells by Lowering Culture Temperature

    OpenAIRE

    Lin, Chi-Yen; Huang, Zhen; Wen, Wei; Wu, Andrew; Wang, Congzhou; Niu, Li

    2015-01-01

    Animal cells and cell lines, such as HEK-293 cells, are commonly cultured at 37°C. These cells are often used to express recombinant proteins. Having a higher expression level or a higher protein yield is generally desirable. As we demonstrate in this study, dropping culture temperature to 33°C, but not lower, 24 hours after transient transfection in HEK-293S cells will give rise to ~1.5-fold higher expression of green fluorescent protein (GFP) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropio...

  7. Design of a trigeneration system using a high temperature fuel cell

    OpenAIRE

    Malico, Isabel; Carvalhinho, Ana Paula; Tenreiro, Joaquim

    2009-01-01

    Fuel cells are one of the technologies available for CHCP, combined heat, cooling and power production, systems. They offer several advantages over more conventional systems, but they still need to overcome a number of barriers until they are readily available for commercialization. At this stage, it is important to fund demonstration projects that experiment with fuel cell technology in pre-commercial situations. In this context, a CHCP system, using a high temperature fuel cell (SOFC) and a...

  8. Electrode Design for Low Temperature Direct-Hydrocarbon Solid Oxide Fuel Cells

    Science.gov (United States)

    Chen, Fanglin (Inventor); Zhao, Fei (Inventor); Liu, Qiang (Inventor)

    2015-01-01

    In certain embodiments of the present disclosure, a solid oxide fuel cell is described. The solid oxide fuel cell includes a hierarchically porous cathode support having an impregnated cobaltite cathode deposited thereon, an electrolyte, and an anode support. The anode support includes hydrocarbon oxidation catalyst deposited thereon, wherein the cathode support, electrolyte, and anode support are joined together and wherein the solid oxide fuel cell operates a temperature of 600.degree. C. or less.

  9. INVESTIGATION ON SILICON SOLAR CELL CAPACITANCE AND ITS DEPENDENCE ON BOTH TEMPERATURE AND INCIDENCE ANGLE

    OpenAIRE

    Moustapha Sané

    2014-01-01

    The aim of this work is to investigate a theoretical study of a vertical junction silicon solar cell capacitance under monochromatic illumination. By solving the continuity equation and using a one dimensional model in frequency modulation, we derive the analytical expressions of both excess minority carrier density and photovoltage. Based on these expressions, the solar cell capacitance was calculated; we then exhibited the effects of both temperature and incidence angle on the solar cell ca...

  10. Polygeneration system based on low temperature solid oxide fuel cell/micro gas turbine hybrid system

    OpenAIRE

    Samavati, Mahrokh

    2012-01-01

    Polygeneration systems attract attention recently because of their high efficiency and low emission compare to the conventional power generation technology. Three different polygeneration systems based on low temperature solid oxide fuel cell, atmospheric solid oxide fuel cell/ micro gas turbine, and pressurized solid oxide fuel cell/ micro gas turbine are mathematically modeled in this study using MATLAB (version 7.12.0.635). These systems are designed to provide space heating, cooling and h...

  11. High Temperature Water Electrolysis Using Metal Supported Solid Oxide Electrolyser Cells (SOEC)

    OpenAIRE

    Schiller, Günter; Ansar, Asif; Lang, Michael; Patz, Olaf

    2009-01-01

    Metal supported cells as developed according to the DLR SOFC concept by applying plasma deposition technologies were investigated for use as solid oxide electrolyser cells (SOEC) for high temperature steam electrolysis. Cells consisting of a porous ferritic steel support, a diffusion barrier layer, a Ni/YSZ hydrogen electrode, a YSZ electrolyte and a LSCF oxygen electrode were electrochemically characterised by means of i-V characteristics and electrochemical impedance spectroscopy measuremen...

  12. Electrode design for low temperature direct-hydrocarbon solid oxide fuel cells

    Science.gov (United States)

    Chen, Fanglin; Zhao, Fei; Liu, Qiang

    2015-10-06

    In certain embodiments of the present disclosure, a solid oxide fuel cell is described. The solid oxide fuel cell includes a hierarchically porous cathode support having an impregnated cobaltite cathode deposited thereon, an electrolyte, and an anode support. The anode support includes hydrocarbon oxidation catalyst deposited thereon, wherein the cathode support, electrolyte, and anode support are joined together and wherein the solid oxide fuel cell operates a temperature of 600.degree. C. or less.

  13. Cell-intrinsic mechanisms of temperature compensation in a grasshopper sensory receptor neuron.

    Science.gov (United States)

    Roemschied, Frederic A; Eberhard, Monika Jb; Schleimer, Jan-Hendrik; Ronacher, Bernhard; Schreiber, Susanne

    2014-01-01

    Changes in temperature affect biochemical reaction rates and, consequently, neural processing. The nervous systems of poikilothermic animals must have evolved mechanisms enabling them to retain their functionality under varying temperatures. Auditory receptor neurons of grasshoppers respond to sound in a surprisingly temperature-compensated manner: firing rates depend moderately on temperature, with average Q10 values around 1.5. Analysis of conductance-based neuron models reveals that temperature compensation of spike generation can be achieved solely relying on cell-intrinsic processes and despite a strong dependence of ion conductances on temperature. Remarkably, this type of temperature compensation need not come at an additional metabolic cost of spike generation. Firing rate-based information transfer is likely to increase with temperature and we derive predictions for an optimal temperature dependence of the tympanal transduction process fostering temperature compensation. The example of auditory receptor neurons demonstrates how neurons may exploit single-cell mechanisms to cope with multiple constraints in parallel.DOI: http://dx.doi.org/10.7554/eLife.02078.001. PMID:24843016

  14. Development of low temperature solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Bakker, W.T.; Goldstein, R. [Electric Power Research Institute, Palo Alto, CA (United States)

    1996-12-31

    The historical focus of the electric utility industry has been central station power plants. These plants are usually sited outside urban areas and electricity was delivered via high voltage transmission lines. Several things are beginning to change this historical precedent One is the popular concern with EMF as a health hazard. This has rendered the construction of new lines as well as upgrading old ones very difficult. Installation of power generating equipment near the customer enables the utility to better utilize existing transmission and distribution networks and defer investments. Power quality and lark of disturbances and interruptions is also becoming increasingly more important to many customers. Grid connected, but dedicated small power plants can greatly improve power quality. Finally the development of high efficiency, low emission, modular fuel cells promises near pollution free localized power generation with an efficiency equal to or exceeding that of even the most efficient central power stations.

  15. Asymptotic diffusion limit of cell temperature discretisation schemes for thermal radiation transport

    International Nuclear Information System (INIS)

    This paper attempts to unify the asymptotic diffusion limit analysis of thermal radiation transport schemes, for a linear-discontinuous representation of the material temperature reconstructed from cell centred temperature unknowns, in a process known as ‘source tilting’. The asymptotic limits of both Monte Carlo (continuous in space) and deterministic approaches (based on linear-discontinuous finite elements) for solving the transport equation are investigated in slab geometry. The resulting discrete diffusion equations are found to have nonphysical terms that are proportional to any cell-edge discontinuity in the temperature representation. Based on this analysis it is possible to design accurate schemes for representing the material temperature, for coupling thermal radiation transport codes to a cell centred representation of internal energy favoured by ALE (arbitrary Lagrange–Eulerian) hydrodynamics schemes

  16. Binary co-generative plants with height temperature SOFC fuel cells

    International Nuclear Information System (INIS)

    In this paper, a field of binary co-generative plants with height temperature SOFC fuel cells is presented. Special attention of application of height temperature SOFC fuel cells and binary co-generative units has been given. These units made triple electricity and heat. Principle of combination of fuel cells with binary cycles has been presented. A model and computer programme for calculation of BKPFC, has been created. By using the program, all the important characteristic-results are calculated: power, efficiency, emission, dimension and economic analysis. On base of results, conclusions and recommendations has been given. (Author)

  17. Simulations on Asymmetric Three-barrier Transmission Coefficients under Different Bias and Temperatures%不同偏压温度下非对称三势垒透射系数的模拟计算

    Institute of Scientific and Technical Information of China (English)

    赵瑞娟; 安盼龙; 许丽萍; 杨艳

    2012-01-01

    非对称多势垒可获得比双势垒更大的共振隧穿电流及更良好的峰谷比。通过分析单电子对任意势垒透射的理论模型,建立了任意非对称三势垒模型,研究了不同偏压和温度对透射系数的影响,并得出结论,为进一步设计非对称量子器件提供理论指导。%Asymmetric multi-barrier can obtain larger resonant tunneling current and better peak-valley ratio than double barrier. By analyzing the theoretical models of single-electron transmission on any harrier, an arbitrary asymmetric three-barrier model was established. Effects of different bias and temperatures on the transmission coefficient were studied. It provides a theoretical guidance for the further design of asymmetric quantum devices.

  18. An induction heating diamond anvil cell for high pressure and temperature micro-Raman spectroscopic measurements.

    Science.gov (United States)

    Shinoda, Keiji; Noguchi, Naoki

    2008-01-01

    A new external heating configuration is presented for high-temperature diamond anvil cell instruments. The supporting rockers are thermally excited by induction from an externally mounted copper coil passing a 30 kHz alternating current. The inductive heating configuration therefore avoids the use of breakable wires, yet is capable of cell temperatures of 1100 K or higher. The diamond anvil cell has no resistive heaters, but uses a single-turn induction coil for elevating the temperature. The induction coil is placed near the diamonds and directly heats the tungsten carbide rockers that support the diamond. The temperature in the cell is determined from a temperature-power curve calibrated by the ratio between the intensities of the Stokes and anti-Stokes Raman lines of silicon. The high-pressure transformation of quartz to coesite is successfully observed by micro-Raman spectroscopy using this apparatus. The induction heating diamond anvil cell is thus a useful alternative to resistively heated diamond anvil cells. PMID:18248060

  19. Dynamic modeling and experimental investigation of a high temperature PEM fuel cell stack

    DEFF Research Database (Denmark)

    Sahlin, Simon Lennart

    2016-01-01

    High temperature polymer fuel cells operating at 100 to 200◦C require simple fuel processing and produce high quality heat that can integrate well with domestic heating systems. Because the transportation of hydrogen is challenging, an alternative option is to reform natural gas on site. This...... article presents the development of a dynamic model and the comparison with experimental data from a high temperature proton exchange membrane fuel cell stack operating on hydrogen with carbon monoxide concentrations up to 0.8%, and temperatures from 155 to 175◦C. The dynamic response of the fuel cell is...... investigated with simulated reformate gas. The dynamic response of the fuel cell stack was compared with a step change in current from 0.09 to 0.18 and back to 0.09 A/cm2 . This article shows that the dynamic model calculates the voltage at steady state well. The dynamic response for a change in current shows...

  20. Temperature dependent current transport properties in Cu2ZnSnS4 solar cells

    International Nuclear Information System (INIS)

    Quaternary semiconductor compound Cu2ZnSnS4 (CZTS) is a promising non-toxic absorber material for solar cells made from earth abundant elements. In this study temperature dependencies (T = 10-300 K) of current-voltage (J-V) characteristics and external quantum efficiency (EQE) spectra of CZTS monograin layer solar cells were measured in order to clarify current transport in CZTS that is still not fully understood. Three different temperature ranges can be distinguished from the temperature dependence of the series resistance (Rs) obtained from J-V measurements and the effective bandgap energy (Eg⁎) determined from the EQE spectra. Thermally activated conductivity, Mott's variable-range hopping conductivity, and very low temperature (< 40 K) blocking of the interface recombination were observed. - Highlights: • Cu2ZnSnS4 monograin layer solar cell temperature dependent parameters were studied. • Thermally activated conductivity at temperatures T > 90 K • Mott's variable-range hopping conductivity at temperatures T = 90-40 K • Very low temperature (< 40 K) blocking of interface recombination was observed

  1. Temperature field analysis for PZT pyroelectric cells for thermal energy harvesting.

    Science.gov (United States)

    Hsiao, Chun-Ching; Ciou, Jing-Chih; Siao, An-Shen; Lee, Chi-Yuan

    2011-01-01

    This paper proposes the idea of etching PZT to improve the temperature variation rate of a thicker PZT sheet in order to enhance the energy conversion efficiency when used as pyroelectric cells. A partially covered electrode was proven to display a higher output response than a fully covered electrode did. A mesh top electrode monitored the temperature variation rate and the electrode area. The mesh electrode width affected the distribution of the temperature variation rate in a thinner pyroelectric material. However, a pyroelectric cell with a thicker pyroelectric material was beneficial in generating electricity pyroelectrically. The PZT sheet was further etched to produce deeper cavities and a smaller electrode width to induce lateral temperature gradients on the sidewalls of cavities under homogeneous heat irradiation, enhancing the temperature variation rate. PMID:22346652

  2. Temperature Field Analysis for PZT Pyroelectric Cells for Thermal Energy Harvesting

    Directory of Open Access Journals (Sweden)

    Chi-Yuan Lee

    2011-11-01

    Full Text Available This paper proposes the idea of etching PZT to improve the temperature variation rate of a thicker PZT sheet in order to enhance the energy conversion efficiency when used as pyroelectric cells. A partially covered electrode was proven to display a higher output response than a fully covered electrode did. A mesh top electrode monitored the temperature variation rate and the electrode area. The mesh electrode width affected the distribution of the temperature variation rate in a thinner pyroelectric material. However, a pyroelectric cell with a thicker pyroelectric material was beneficial in generating electricity pyroelectrically. The PZT sheet was further etched to produce deeper cavities and a smaller electrode width to induce lateral temperature gradients on the sidewalls of cavities under homogeneous heat irradiation, enhancing the temperature variation rate.

  3. Further Improvement and System Integration of High Temperature Polymer Electrolyte Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Li, Qingfeng

    Polymer electrolyte membrane fuel cell (PEMFC) technology based on Nafion membranes can operate at temperatures around 80°C. The new development in the field is high temperature PEMFC for operation above 100°C, which has been successfully demonstrated through the previous EC Joule III and the 5th...... system integration of the high temperature PEMFC. The strategic developments of the FURIM are in three steps: (1) further improvement of the high temperature polymer membranes and related materials; (2) development of technological units including fuel cell stack, hydrocarbon reformer, afterburner and......, conductivity, mechanical and other properties. For this purpose, basic polymers will be first synthesized and optimized. Different routes to functionalize the polymers will be explored to increate proton conductivity. By the development of advanced materials, demonstration of the high temperature PEMFC stack...

  4. Temperature distributions in the laser-heated diamond anvil cell from 3-D numerical modeling

    International Nuclear Information System (INIS)

    We present TempDAC, a 3-D numerical model for calculating the steady-state temperature distribution for continuous wave laser-heated experiments in the diamond anvil cell. TempDAC solves the steady heat conduction equation in three dimensions over the sample chamber, gasket, and diamond anvils and includes material-, temperature-, and direction-dependent thermal conductivity, while allowing for flexible sample geometries, laser beam intensity profile, and laser absorption properties. The model has been validated against an axisymmetric analytic solution for the temperature distribution within a laser-heated sample. Example calculations illustrate the importance of considering heat flow in three dimensions for the laser-heated diamond anvil cell. In particular, we show that a “flat top” input laser beam profile does not lead to a more uniform temperature distribution or flatter temperature gradients than a wide Gaussian laser beam

  5. Low-EC-Content Electrolytes for Low-Temperature Li-Ion Cells

    Science.gov (United States)

    Smart, Marshall; Bugga, Ratnakumar; Surampudi, Subbarao

    2003-01-01

    Electrolytes comprising LiPF6 dissolved at a concentration of 1.0 M in three different mixtures of alkyl carbonates have been found well suited for use in rechargeable lithium-ion electrochemical cells at low temperatures. These and other electrolytes have been investigated in continuing research directed toward extending the lower limit of practical operating temperatures of Li-ion cells down to -60 C. This research at earlier stages was reported in numerous previous NASA Tech Briefs articles, the three most recent being "Ethyl Methyl Carbonate as a Cosolvent for Lithium-Ion Cells" (NPO-20605), Vol. 25, Low-EC-Content Electrolytes for Low-Temperature Li-Ion Cells No. 6 (June 2001), page 53; "Alkyl Pyrocarbonate Electrolyte Additives for Li-Ion Cells" (NPO-20775), Vol. 26, No. 5 (May 2002), page 37; and "Fluorinated Alkyl Carbonates as Cosolvents in Li-Ion Cells (NPO-21076), Vol. 26, No. 5 (May 2002), page 38. The present solvent mixtures, in terms of volume proportions of their ingredients, are 1 ethylene carbonate (EC) + 1 diethyl carbonate (DEC) + 1 dimethyl carbonate (DMC) + 3 ethyl methyl carbonate (EMC); 3EC + 3DMC + 14EMC; and 1EC + 1DEC + 1DMC + 4EMC. Relative to similar mixtures reported previously, the present mixtures, which contain smaller proportions of EC, have been found to afford better performance in experimental Li-ion cells at temperatures < -20 C.

  6. Cobalt based layered perovskites as cathode material for intermediate temperature Solid Oxide Fuel Cells: A brief review

    Science.gov (United States)

    Pelosato, Renato; Cordaro, Giulio; Stucchi, Davide; Cristiani, Cinzia; Dotelli, Giovanni

    2015-12-01

    Nowadays, the cathode is the most studied component in Intermediate Temperature-Solid Oxide Fuel Cells (IT-SOFCs). Decreasing SOFCs operating temperature implies slow oxygen reduction kinetics and large polarization losses. Double perovskites with general formula REBaCo2O5+δ are promising mixed ionic-electronic conductors, offering a remarkable enhancement of the oxygen diffusivity and surface exchange respect to disordered perovskites. In this review, more than 250 compositions investigated in the literature were analyzed. The evaluation was performed in terms of electrical conductivity, Area Specific Resistance (ASR), chemical compatibility with electrolytes and Thermal Expansion Coefficient (TEC). The most promising materials have been identified as those bearing the mid-sized rare earths (Pr, Nd, Sm, Gd). Doping strategies have been analyzed: Sr doping on A site promotes higher electrical conductivity, but worsen ASR and TECs; B-site doping (Fe, Ni, Mn) helps lowering TECs, but is detrimental for the electrochemical properties. A promising boost of the electrochemical activity is obtained by simply introducing a slight Ba under-stoichiometry. Still, the high sensitivity of the electrochemical properties against slight changes in the stoichiometry hamper a conclusive comparison of all the investigated compounds. Opportunities for an improvement of double perovskite cathodes performance is tentatively foreseen in combining together the diverse effective doping strategies.

  7. Diffusion coefficients for absorbing materials

    International Nuclear Information System (INIS)

    A method to improve the diffusion results for systems containing strong absorbers is described. Each absorbing material is transformed into an equivalent rectangle. Transport and diffusion calculations in slab geometry are performed for both directions of the rectangle, and group-dependent diffusion coefficients are determined by matching the outgoing currents. Test problems comprise a critical slab, a compact PWR fuel element storage pool and two BWR fuel elements with a control rod and a poison cell. The multiplication factors of these systems are calculated with an accuracy of 1 to 2%. (Auth.)

  8. Do Fresnel coefficients exist?

    OpenAIRE

    Felbacq, D; Guizal, B.; F Zolla

    2001-01-01

    The starting point of the article is the puzzling fact that one cannot recover the Fresnel coefficients by letting tend the width of a slab to infinity. Without using the so-called limiting absorption principle, we show by a convenient limit analysis that it is possible to define rigorously the field diffracted by a semi-infinite periodic medium.

  9. Inverse determination of local heat transfer coefficient

    International Nuclear Information System (INIS)

    The naphtalene sublimation and transient methods are widely used techniques which are particularly useful in complex flows and solid shapes. Both techniques have been widely used with considerable success but they are not appropriate for high temperatures. An alternative method to obtain the local convective heat transfer coefficient, that does not have any disadvantages noted above, is the inverse procedure. Determination of the space-variable heat transfer coefficient on a complex shape surface requires the solution of the nonlinear inverse heat conduction problem. The distribution of the heat transfer coefficient is calculated from temperature measurements at interior points of the solid and measured fluid temperature. The unknown parameters associated with the solution are selected to achieve the closest agreement in a least squares sense between the computed and measured temperatures using the Levenberg - Marquardt method. The nonlinear least - squares problem is parameterized by assuming the staircase changes of heat transfer coefficient on the boundary or expressing the space variations of the heat transfer coefficient in the functional form. The uncertainties in the estimated components of the heat transfer coefficient or in the estimated parameters are determined for the temperature measurements with known and unknown standard deviations. The determination of the circumferential heat transfer coefficient distribution on the heated tube with two longitudinal fins in cross flow demonstrates the accuracy of the developed method. The actual experimental data were used. Experiments were performed with an array of vertical tubes arranged in staggered pattern. The experimental results reported herein are among the first that show the variation of the local heat transfer coefficients over the circumference of the finned tube. Most data reported previously were acquired for smooth tubes at low temperatures. The main advantage of the method is that it does not

  10. High-Energy-Density, Low-Temperature Li/CFx Primary Cells

    Science.gov (United States)

    Whitacre, Jay; Bugga, Ratnakumar; Smart, Marshall; Prakash, G.; Yazami, Rachid

    2007-01-01

    High-energy-density primary (nonrechargeable) electrochemical cells capable of relatively high discharge currents at temperatures as low as -40 C have been developed through modification of the chemistry of commercial Li/CFx cells and batteries. The commercial Li/CFx units are not suitable for high-current and low-temperature applications because they are current limited and their maximum discharge rates decrease with decreasing temperature. The term "Li/CFx" refers to an anode made of lithium and a cathode made of a fluorinated carbonaceous material (typically graphite). In commercial cells, x typically ranges from 1.05 to 1.1. This cell composition makes it possible to attain specific energies up to 800 Wh/kg, but in order to prevent cell polarization and the consequent large loss of cell capacity, it is typically necessary to keep discharge currents below C/50 (where C is numerically equal to the current that, flowing during a charge or discharge time of one hour, would integrate to the nominal charge or discharge capacity of a cell). This limitation has been attributed to the low electronic conductivity of CFx for x approx. 1. To some extent, the limitation might be overcome by making cathodes thinner, and some battery manufacturers have obtained promising results using thin cathode structures in spiral configurations. The present approach includes not only making cathodes relatively thin [.2 mils (.0.051 mm)] but also using sub-fluorinated CFx cathode materials (x 1. It was known from recent prior research that cells containing sub-fluorinated CFx cathodes (x between 0.33 and 0.66) are capable of retaining substantial portions of their nominal low-current specific energies when discharged at rates as high as 5C at room temperature. However, until experimental cells were fabricated following the present approach and tested, it was not known whether or to what extent low-temperature performance would be improved.

  11. The Effect of SiO2-TiO2-Al2O3 Mixture Addition on the CuFe2O4 Ceramic for Negative Temperature Coefficient Thermistor

    International Nuclear Information System (INIS)

    The effect of SiO2-TiO2-Al2O3 mixture addition on the characteristics of CuFe2O4 ceramics for Negative Temperature Coefficient (NTC) thermistors has been studied. The ceramics were produced by pressing a homogenous mixture of composition 1: CuO, Fe3O4 and SiO2-TiO2-Al2O3 (0,5; 0,5 dan 0,5 w/o), composition 2: CuO, Fe3O4 dan SiO2-TiO2-Al2O3 (0,5; 0,5 and 1,0 w/o) and composition 3 : CuO, Fe3O4 and SiO2-TiO2-Al2O3 (0,5; 0,5 and 2,0 w/o) in appropriate proportions to produce CuFe2O4 based ceramics. The pressed powders were then sintered at 1100 oC for 2 hours in air. Electrical characterization was done by measuring electrical resistivity of the ceramics at various temperatures (25 oC - I00 oC). Microstructure and structure analysis were also carried out by using optical microscope and x-ray diffractometer (XRD), respectively. The XRD analyses showed that the CuFe2O4 and SiO2-TiO2-Al2O3 mixture added - CuFe2O4 ceramics have crystal structure of tetragonal spinel and the presence of second phase could not be identified. According to the electrical data, it was known that addition of the SiO2-TiO2-Al2O3 mixture changed the thermistor constant (B) and the temperature electrical resistivity (ρRT). The value of B of 2807-3293 oK and (ρRT) of 3,4-5,3 κΩcm of the produced CuFe2O4 based ceramics fitted market requirement. (author)

  12. The "Micromorph" cell: a New Way to High-Efficiency-Low-Temperature Crystalline Silicon Thin-Film Cell Manufacturing ?

    OpenAIRE

    Keppner, H.; Kroll, U.; Torres, P.; J. Meier; Platz, R.; Fischer, D.; Beck, N; Dubail, S.; Anna Selvan, J. A.; Pellaton Vaucher, N.; Goerlitzer, M.; Ziegler, Y.; Tscharner, R.; Hof, Ch.; Goetz, M

    1997-01-01

    Hydrogenated microcrystalline Silicon (µc-Si:H) produced by the VHF-GD (Very High Frequency Glow Discharge) process can be considered to be a new base material for thin-film crystalline silicon solar cells. The most striking feature of such cells, in contrast to conventional amorphous silicon technology, is their stability under light-soaking. With respect to crystalline silicon technology, their most striking advantage is their low process temperature (220 °C). The so called “micromorph” cel...

  13. In Situ Irradiation and Measurement of Triple Junction Solar Cells at Low Intensity, Low Temperature (LILT) Conditions

    Science.gov (United States)

    Harris, R.D.; Imaizumi, M.; Walters, R.J.; Lorentzen, J.R.; Messenger, S.R.; Tischler, J.G.; Ohshima, T.; Sato, S.; Sharps, P.R.; Fatemi, N.S.

    2008-01-01

    The performance of triple junction InGaP/(In)GaAs/Ge space solar cells was studied following high energy electron irradiation at low temperature. Cell characterization was carried out in situ at the irradiation temperature while using low intensity illumination, and, as such, these conditions reflect those found for deep space, solar powered missions that are far from the sun. Cell characterization consisted of I-V measurements and quantum efficiency measurements. The low temperature irradiations caused substantial degradation that differs in some ways from that seen after room temperature irradiations. The short circuit current degrades more at low temperature while the open circuit voltage degrades more at room temperature. A room temperature anneal after the low temperature irradiation produced a substantial recovery in the degradation. Following irradiation at both temperatures and an extended room temperature anneal, quantum efficiency measurement suggests that the bulk of the remaining damage is in the (In)GaAs sub-cell

  14. Low temperature-induced cell surface membrane vesicle shedding is associated with DNA fragmentation

    International Nuclear Information System (INIS)

    Temperature shift conditions of 0 degree to 22 degrees C or 0 degree to 37 degrees C induce the formation and shedding of membrane vesicles (MV) from P815 tumor cell surfaces. When the MV shedding process takes place at 22 degrees C it occurs without changes in cell surface membrane permeability, whereas at 37 degrees C, changes in permeability to 51Cr and trypan blue do occur, thus mimicking the lymphocyte-mediated lytic process of tumor cells. The present studies demonstrate that nuclear DNA fragmentation also occurs in both 0 degree to 22 degrees C and 0 degree to 37 degrees C temperature shifts. However, cell surface membrane permeability to DNA fragments occurs only in the latter condition, i.e., 0 degree to 37 degrees C. The microtubule-stabilizing agent deuterium oxide (D2O) inhibited the MV shedding process, the changes in membrane permeability, and DNA fragmentation. When P815 cells which had been induced to shed MV by the 0 degree to 22 degrees C temperature shift were labeled with 51Cr and used as targets for alloimmune lymphocytes, they were found to be as susceptible to T-cell lysis as control P815 cells. This result indicates that the lytic effect of alloimmune T lymphocytes can be exerted at the target cell surface membrane level independently of nuclear DNA fragmentation

  15. Temperature increase in nanostructured cells of a magnetic tunnel junction during current-induced magnetization switching

    International Nuclear Information System (INIS)

    Three-dimensional numerical calculations based on the finite element method are performed to calculate the increase in the temperature in nanostructured cells of a magnetic tunnel junction under conditions that are relevant to current-induced magnetization switching for a high-density magnetic random access memory. Three key parameters, the lateral size, the resistance-area product and the applied current density, were varied widely so that their effects on the temperature increase could be examined. The computed results for the temperature increase, as a function of the resistance-area product and the current density, show the same trends that are expected from an equation for the dissipated heat. While the increase in the temperature is expected to be independent of the lateral size, the computations reveal a rather complicated relationship between the two variables, which is contingent on the various conditions that are considered. In a cell array that is relevant to high-density contexts, the temperature increase in the nearest cells is as high as 50% of the cell at which the current is directly applied; this could cause a thermal-stability problem in high-density magnetic random access memories. The temperature increase was also calculated under a more realistic physical picture of the relaxation of tunnelled electrons. These results are in agreement with those that are computed from Joule heating.

  16. Preparation and catalytic performance of temperature-responsive cell-like particles.

    Science.gov (United States)

    Yang, Qiufeng; Dai, Zhao; Guo, Wenjuan; Chu, Yuanyuan; Chen, Guangping

    2014-09-01

    A novel kind of cell-like particles as temperature-responsive catalysts was presented in this paper. First, uniform α-Fe₂O₃shuttle-like nanoparticles were prepared by homogeneous hydrolysis. Then, these α-Fe₂O₃particles were coated by Au nanoparticles (AuNPs), SiO₂and poly (N-isopropylacrylamide) (PNIPAM), respectively. After the removal of SiO₂layer by etching with HF solution, the cell-like particles were prepared when the α-Fe₂O₃, AuNPs, and PNIPAM were as cell nucleus, catalysts, and cell membranes, respectively. These cell-like particles showed a novel temperature-responsively catalytic performance because the PNIPAM shell could change its hydrophilicity and swelling capacity under different temperature. When the temperature was 25°C, the yield of 4-aminophenol (4-AP) from 4-nitrophenol (4-NP) by reduction of NaBH₄was about 100% in 15 min, while the yield of 4-AP was about 90.5% in 40 min. when the temperature was 40°C. PMID:25262506

  17. Novel Method for Measuring Temperature Distribution within Fuel Cell using Microsensors

    Science.gov (United States)

    Lee, Chi-Yuan; Hsieh, Chi-Lieh; Wu, Guan-Wei

    2007-05-01

    A fuel cell has the potential to become an important source of electric power. However, measuring the temperature inside the fuel cell is difficult. Hence, in this investigation, an array of microsensors is set up inside the fuel cell to measure the temperature distribution. The substrate of a bipolar plate in the fuel cell is stainless steel (SS-316) and an electroforming technique is implemented to fabricate channels in the stainless steel substrate. Then micro-electro-mechanical system (MEMS) technologies are employed to fabricate a platinum temperature sensor on the rib of a channel in the stainless steel substrate. In this experiment, the temperature of microsensor is measured to range from 31 to 80 °C and its resistance ranges from 0.593 to 0.649 Ω. Experimental results demonstrate that temperature is almost linearly related to resistance and that accuracy and sensitivity are 0.5 °C and 1.93× 10-3/°C, respectively. The performance curves of a single fuel cell operating at 34 °C and H2/O2 gas flow rates of 50/50 ml/min are determined. The maximum power density is 170 mW/cm2 and the current density is 513 mA/cm2.

  18. Low-temperature-processed a-SiOx:H/a-Si:H tandem cells for full spectrum solar cells

    Science.gov (United States)

    Kang, Dong-Won; Sichanugrist, Porponth; Miyajima, Shinsuke; Konagai, Makoto

    2015-08-01

    We developed wide-bandgap amorphous silicon (a-Si:H) and amorphous silicon oxide (a-SiOx:H) absorbers by extremely decreasing deposition temperature to as low as 100 °C. By adjusting hydrogen and carbon dioxide gas flow rates, device-quality absorbers and thus suitable single junction cells were obtained. An a-SiOx:H single-junction cell (i = 100 nm) fabricated employing the absorber we developed showed an open circuit voltage (Voc) of 1.007 V and a fill factor of 0.741, which are better than those of a-Si:H cells. This a-SiOx:H cell was introduced in a-SiOx:H/a-Si:H tandem cells as the top cell, which contributed to the achievement of a markedly high Voc of 1.910 V. This tandem cell with an efficiency of 9.25% showed better Voc and current matching property than the a-Si:H/a-Si:H (8.74%) tandem structure. The low-temperature-gradient a-SiOx:H/a-Si:H tandem cells can be a promising configuration for spectrum splitting applications.

  19. High-Temperature Experiments using a Resistively-Heated High-Pressure Membrane Diamond Anvil Cell

    Energy Technology Data Exchange (ETDEWEB)

    Jenei, Z; Visbeck, K; Cynn, H; Yoo, C; Evans, W

    2009-04-22

    A reliable high-performance heating method using resistive heaters and a membrane driven diamond anvil cell (mDAC) is presented. Two micro-heaters are mounted in a mDAC and use electrical power of less than 150 W to achieve sample temperatures up to 1200 K. For temperature measurement we use two K-type thermocouples mounted near the sample. The approach can be used for in-situ Raman spectroscopy and x-ray diffraction at high pressures and temperatures. A W-Re alloy gasket material permits stable operation of mDAC at high temperature. Using this method, we made an isothermal compression at 900 K to pressures in excess of 100 GPa and isobaric heating at 95 GPa to temperatures in excess of 1000 K. As an example, we present high temperature Raman spectroscopy measurements of nitrogen at high pressures.

  20. Enhancement of Power Efficiency and Stability of P3HT-Based Organic Solar Cells under Elevated Operating-Temperatures by Using a Nanocomposite Photoactive Layer

    Directory of Open Access Journals (Sweden)

    Tran Thi Thao

    2015-01-01

    Full Text Available With the aim to find out an enhanced operating-temperature range for photovoltaic device parameters, two types of the photoactive layer were prepared: poly(3-hexylthiophene (P3HT and P3HT+nc-TiO2 (PTC thin films. The enhancement obtained for the photoelectrical conversion efficiency of the composite based OSCs is attributed to the presence of nanoheterojunctions of TiO2/P3HT. For the temperature range of 30–70°C, the decrease of the open-circuit potential was compensated by an increase of the fill factor; and the increase in the short-circuit current resulted in an overall increase of the energy conversion efficiency. At elevated temperatures of 60–80°C the efficiency of the P3HT- and PTC-based cells reached a maximum value of 1.6% and 2.1%, respectively. Over this temperature range the efficiency of P3HT-based OSC decreased strongly to zero, whereas for the PTC cells it maintained a value as large as 1.2% at the temperature range of 110–140°C. The improved thermal stability of the composite-based device was attributed to the lowered thermal expansion coefficient of the nanocomposite photoactive layer.