Zero field reversal probability in thermally assisted magnetization reversal

Science.gov (United States)

Prasetya, E. B.; Utari; Purnama, B.

2017-11-01

This paper discussed about zero field reversal probability in thermally assisted magnetization reversal (TAMR). Appearance of reversal probability in zero field investigated through micromagnetic simulation by solving stochastic Landau-Lifshitz-Gibert (LLG). The perpendicularly anisotropy magnetic dot of 50×50×20 nm3 is considered as single cell magnetic storage of magnetic random acces memory (MRAM). Thermally assisted magnetization reversal was performed by cooling writing process from near/almost Curie point to room temperature on 20 times runs for different randomly magnetized state. The results show that the probability reversal under zero magnetic field decreased with the increase of the energy barrier. The zero-field probability switching of 55% attained for energy barrier of 60 k B T and the reversal probability become zero noted at energy barrier of 2348 k B T. The higest zero-field switching probability of 55% attained for energy barrier of 60 k B T which corespond to magnetif field of 150 Oe for switching.

Magnetic resonance of field-frozen and zero-field-frozen magnetic fluids

International Nuclear Information System (INIS)

Pereira, A.R.; Pelegrini, F.; Neto, K. Skeff; Buske, N.; Morais, P.C.

2004-01-01

In this study magnetic resonance was used to investigate magnetic fluid samples frozen under zero and non-zero (15 kG) external fields. The magnetite-based sample containing 2x10 17 particle/cm 3 was investigated from 100 to 400 K. Analysis of the temperature dependence of the resonance field revealed bigger magnetic structures in the frozen state than in the liquid phase. Also, differences in the mesoscopic organization in the frozen state may explain the data obtained from samples frozen under zero and non-zero fields

Quantum Quench Dynamics in the Transverse Field Ising Model at Non-zero Temperatures

Science.gov (United States)

Abeling, Nils; Kehrein, Stefan

The recently discovered Dynamical Phase Transition denotes non-analytic behavior in the real time evolution of quantum systems in the thermodynamic limit and has been shown to occur in different systems at zero temperature [Heyl et al., Phys. Rev. Lett. 110, 135704 (2013)]. In this talk we present the extension of the analysis to non-zero temperature by studying a generalized form of the Loschmidt echo, the work distribution function, of a quantum quench in the transverse field Ising model. Although the quantitative behavior at non-zero temperatures still displays features derived from the zero temperature non-analyticities, it is shown that in this model dynamical phase transitions do not exist if T > 0 . This is a consequence of the system being initialized in a thermal state. Moreover, we elucidate how the Tasaki-Crooks-Jarzynski relation can be exploited as a symmetry relation for a global quench or to obtain the change of the equilibrium free energy density. This work was supported through CRC SFB 1073 (Project B03) of the Deutsche Forschungsgemeinschaft (DFG).

Repulsive Casimir force at zero and finite temperature

International Nuclear Information System (INIS)

Lim, S C; Teo, L P

2009-01-01

We study the zero and finite temperature Casimir force acting on a perfectly conducting piston with arbitrary cross section moving inside a closed cylinder with infinitely permeable walls. We show that at any temperature, the Casimir force always tends to move the piston away from the walls and toward its equilibrium position. In the case of a rectangular piston, exact expressions for the Casimir force are derived. In the high-temperature regime, we show that the leading term of the Casimir force is linear in temperature and therefore the Casimir force has a classical limit. Due to duality, all these results also hold for an infinitely permeable piston moving inside a closed cylinder with perfectly conducting walls.

Fast, Computer Supported Experimental Determination of Absolute Zero Temperature at School

Science.gov (United States)

Bogacz, Bogdan F.; Pedziwiatr, Antoni T.

2014-01-01

A simple and fast experimental method of determining absolute zero temperature is presented. Air gas thermometer coupled with pressure sensor and data acquisition system COACH is applied in a wide range of temperature. By constructing a pressure vs temperature plot for air under constant volume it is possible to obtain--by extrapolation to zero…

Deconstructing scalar QED at zero and finite temperature

International Nuclear Information System (INIS)

Kan, N.; Sakamoto, K.; Shiraishi, K.

2003-01-01

We calculate the effective potential for the WLPNGB in a world with a circular latticized extra dimension. The mass of the Wilson line pseudo-Nambu-Goldstone boson (WLPNGB) is calculated from the one-loop quantum effect of scalar fields at zero and finite temperature. We show that a series expansion by the modified Bessel functions is useful to calculate the one-loop effective potentials. (orig.)

Compressibility, zero sound, and effective mass of a fermionic dipolar gas at finite temperature

International Nuclear Information System (INIS)

Kestner, J. P.; Das Sarma, S.

2010-01-01

The compressibility, zero-sound dispersion, and effective mass of a gas of fermionic dipolar molecules is calculated at finite temperature for one-, two-, and three-dimensional uniform systems, and in a multilayer quasi-two-dimensional system. The compressibility is nonmonotonic in the reduced temperature, T/T F , exhibiting a maximum at finite temperature. This effect might be visible in a quasi-low-dimensional experiment, providing a clear signature of the onset of many-body quantum degeneracy effects. The collective mode dispersion and effective mass show similar nontrivial temperature and density dependence. In a quasi-low-dimensional system, the zero-sound mode may propagate at experimentally attainable temperatures.

Zero-temperature renormalization of the 2D transverse Ising model

International Nuclear Information System (INIS)

Kamieniarz, G.

1982-08-01

A zero-temperature real-space renormalization-group method is applied to the transverse Ising model on planar hexagonal, triangular and quadratic lattices. The critical fields and the critical exponents describing low-field large-field transition are calculated. (author)

Quantum and classical vacuum forces at zero and finite temperature; Quantentheoretische und klassische Vakuum-Kraefte bei Temperatur Null und bei endlicher Temperatur

Energy Technology Data Exchange (ETDEWEB)

Niekerken, Ole

2009-06-15

In this diploma thesis the Casimir-Polder force at zero temperature and at finite temperatures is calculated by using a well-defined quantum field theory (formulated in position space) and the method of image charges. For the calculations at finite temperature KMS-states are used. The so defined temperature describes the temperature of the electromagnetic background. A one oscillator model for inhomogeneous dispersive absorbing dielectric material is introduced and canonically quantized to calculate the Casimir-Polder force at a dielectric interface at finite temperature. The model fulfils causal commutation relations and the dielectric function of the model fulfils the Kramer-Kronig relations. We then use the same methods to calculate the van der Waals force between two neutral atoms at zero temperature and at finite temperatures. It is shown that the high temperature behaviour of the Casimir-Polder force and the van der Waals force are independent of {Dirac_h}. This means that they have to be understood classically, what is then shown in an algebraic statistical theory by using classical KMS states. (orig.)

Energy and contact of the one-dimensional Fermi polaron at zero and finite temperature.

Science.gov (United States)

Doggen, E V H; Kinnunen, J J

2013-07-12

We use the T-matrix approach for studying highly polarized homogeneous Fermi gases in one dimension with repulsive or attractive contact interactions. Using this approach, we compute ground state energies and values for the contact parameter that show excellent agreement with exact and other numerical methods at zero temperature, even in the strongly interacting regime. Furthermore, we derive an exact expression for the value of the contact parameter in one dimension at zero temperature. The model is then extended and used for studying the temperature dependence of ground state energies and the contact parameter.

Spin critical opalescence in zero-temperature Bose-Einstein condensates

Science.gov (United States)

Santamore, D. H.; Timmermans, E.

2012-02-01

Cold-atom developments suggest the prospect of measuring scaling properties and long-range fluctuations of continuous phase transitions at zero temperature. We discuss the conditions for characterizing the phase separation of Bose-Einstein condensates of boson atoms in two distinct hyperfine spin states. The mean-field description breaks down as the system approaches the transition from the miscible side. An effective spin description clarifies the ferromagnetic nature of the transition. We show that a difference in the scattering lengths for the bosons in the same spin state leads to an effective internal magnetic field. The point at which the internal magnetic field vanishes (i.e., equal values of the like-boson scattering lengths) is a special point. We show that the long-range density fluctuations are suppressed near that point, while the effective spin exhibits the long-range fluctuations that characterize critical points. The zero-temperature system exhibits critical opalescence with respect to long-wavelength waves of impurity atoms that interact with the bosons in a spin-dependent manner.

The SU(3) topological susceptibility at zero and finite temperature: A lattice Monte Carlo evaluation

International Nuclear Information System (INIS)

Teper, M.; Oxford Univ.

1988-01-01

We extend previous calculations of the zero-temperature topological susceptibility, Χ t , to larger lattices (up to 20 4 ) and smaller lattice spacings (up to β = 6.2). Using a new technique we are able to achieve a precise control of finite size corrections. We confirm, with much greater systematic and statistical precision, that the dimensionless ratio Χ t /K 2 is independent of β for β ≥ 5.7. This enables us to extract Χ t in physical units and we find Χ t = (179 ± 4 MeV) 4 - statistical error only - which is in striking agreement with the Witten-Veneziano calculation. We also investigate the previously observed fact that Χ t is suppressed as the temperature is raised through the deconfining transition. We find that Χ t is in fact discontinuous at the place transition and that its temperature dependence is otherwise weak as long as it remains in a single well-defined phase. (orig.)

Zero-Sum Flows in Designs

International Nuclear Information System (INIS)

Akbari, S.; Khosrovshahi, G.B.; Mofidi, A.

2010-07-01

Let D be a t-(v, k, λ) design and let N i (D), for 1 ≤ i ≤ t, be the higher incidence matrix of D, a (0, 1)-matrix of size (v/i) x b, where b is the number of blocks of D. A zero-sum flow of D is a nowhere-zero real vector in the null space of N 1 (D). A zero-sum k-flow of D is a zero-sum flow with values in {±,...,±(k-1)}. In this paper we show that every non-symmetric design admits an integral zero-sum flow, and consequently we conjecture that every non-symmetric design admits a zero-sum 5-flow. Similarly, the definition of zero-sum flow can be extended to N i (D), 1 ≤ i ≤ t. Let D = t-(v,k, (v-t/k-t)) be the complete design. We conjecture that N t (D) admits a zero-sum 3-flow and prove this conjecture for t = 2. (author)

Population dynamics of excited atoms in non-Markovian environments at zero and finite temperature

International Nuclear Information System (INIS)

Zou Hong-Mei; Fang Mao-Fa

2015-01-01

The population dynamics of a two-atom system, which is in two independent Lorentzian reservoirs or in two independent Ohmic reservoirs respectively, where the reservoirs are at zero temperature or finite temperature, is studied by using the time-convolutionless master-equation method. The influences of the characteristics and temperature of a non-Markovian environment on the population of the excited atoms are analyzed. We find that the population trapping of the excited atoms is related to the characteristics and the temperature of the non-Markovian environment. The results show that, at zero temperature, the two atoms can be effectively trapped in the excited state both in the Lorentzian reservoirs and in the Ohmic reservoirs. At finite temperature, the population of the excited atoms will quickly decay to a nonzero value. (paper)

Zero sound velocity in π, ρ mesons at different temperatures

International Nuclear Information System (INIS)

Dey, J.; Dey, M.; Tomio, L.; Araujo, C.F. de Jr.

1994-07-01

Sharp transitions are perhaps absent in QCD, so that one looks for physical quantities which may reflect the phase change. One such quantity is the sound velocity which was shown in lattice theory to become zero at the transition point for pure glue. We show that even in a simple bag model the sound velocity goes to zero at temperature T=T ν ≠ 0 and that the numerical value of this T ν depends on the nature of the meson. The average thermal energy of mesons go linearly with T near T ν , with much smaller slope for the pion. The T ν - s can be connected with the Boltzmann temperatures obtained from transverse momentum spectrum of these mesons in heavy ion collision at mid-rapidity. It would be interesting to check the presence of different T ν - s in present day finite T lattice theory. (author). 22 refs, 1 fig., 2 tabs

A dual-unit pressure sensor for on-chip self-compensation of zero-point temperature drift

International Nuclear Information System (INIS)

Wang, Jiachou; Li, Xinxin

2014-01-01

A novel dual-unit piezoresistive pressure sensor, consisting of a sensing unit and a dummy unit, is proposed and developed for on-chip self-compensation for zero-point temperature drift. With an MIS (microholes inter-etch and sealing) process implemented only from the front side of single (1 1 1) silicon wafers, a pressure sensitive unit and another identically structured pressure insensitive dummy unit are compactly integrated on-chip to eliminate unbalance factors induced zero-point temperature-drift by mutual compensation between the two units. Besides, both units are physically suspended from silicon substrate to further suppress packaging-stress induced temperature drift. A simultaneously processes ventilation hole-channel structure is connected with the pressure reference cavity of the dummy unit to make it insensitive to detected pressure. In spite of the additional dummy unit, the sensor chip dimensions are still as small as 1.2 mm × 1.2 mm × 0.4 mm. The proposed dual-unit sensor is fabricated and tested, with the tested sensitivity being 0.104 mV kPa −1 3.3 V −1 , nonlinearity of less than 0.08% · FSO and overall accuracy error of ± 0.18% · FSO. Without using any extra compensation method, the sensor features an ultra-low temperature coefficient of offset (TCO) of 0.002% °C −1 · FSO that is much better than the performance of conventional pressure sensors. The highly stable and small-sized sensors are promising for low cost production and applications. (paper)

Ikaite solubility in seawater-derived brines at 1 atm and sub-zero temperatures to 265 K

Science.gov (United States)

Papadimitriou, Stathys; Kennedy, Hilary; Kennedy, Paul; Thomas, David N.

2013-05-01

The concentration-based (stoichiometric) equilibrium solubility product of ikaite (CaCO3·6H2O) in seawater and cryogenic seawater-derived brines was determined at 1 atm total pressure over the temperature range from -1.1 to -7.5 °C and the salinity range from 34 to 124 in temperature-salinity pairs representative of sea ice brines. The solubility measurements were obtained in solutions that were undersaturated and supersaturated with respect to ikaite by equilibration with CO2/N2 gas mixtures of known pCO2 (20-400 μatm). The solutions were then equilibrated with synthetic ikaite (seed) for up to 3 months in a closed system. Arrival of the solid-solution system at a long-term chemical equilibrium was indicated by attainment of constant chemical solution composition with respect to total dissolved calcium, total dissolved inorganic carbon, and total alkalinity. Using these measurements, the stoichiometric equilibrium solubility product of ikaite (Ksp,ikaite∗=[Ca][CO32-], in molkgsolution-2) was determined, with the carbonate ion concentration computed from the measured total alkalinity and total dissolved inorganic carbon concentrations. The computed carbonate ion concentration and, by extension, the Ksp,ikaite∗ are both contingent on solving the system of equations that describe the parameters of the CO2 system in seawater by extrapolation to the experimental salinity and temperature conditions. The results show that the pKsp,ikaite∗=-logKsp,ikaite∗ in seawater of salinity 34 at -1.1 °C was 5.362 ± 0.004 and that the pKsp,ikaite∗ in sea ice at the freezing point of brines of salinity greater than 34 can be described as a function of temperature (T, in K) by the equation, pKsp,ikaite∗=-15489.09608+623443.70216T-1+2355.14596lnT, in the temperature range of 265.15 K 1 month) approach to chemical equilibrium when incubated without seeding ikaite crystals. Simple modeling indicated that ikaite should not precipitate from sea ice brines evolving under

Kinetics of ikaite precipitation and dissolution in seawater-derived brines at sub-zero temperatures to 265 K

Science.gov (United States)

Papadimitriou, Stathys; Kennedy, Hilary; Kennedy, Paul; Thomas, David N.

2014-09-01

The kinetics of calcium carbonate hexahydrate (ikaite) precipitation and dissolution were investigated in seawater and seawater-derived brines at sub-zero temperatures using the constant addition experimental technique. The steady state rate of these two processes was found to be a function of the deviation of the solution from equilibrium with respect to ikaite and conformed to the same empirical rate law as the anhydrous CaCO3 polymorphs, calcite and aragonite. In addition to the saturation state of the brine with respect to ikaite, the salinity of the brine and the temperature of the reaction evidently exerted some control on the ikaite precipitation kinetics, while the dissolution kinetics of the polymorph were not noticeably influenced by these two parameters. The experimental salinity and temperature conditions were equivalent to those at thermal equilibrium between brine and ice in the sea ice cover of polar seas. Simple modelling of the CO2 system by extrapolation of the oceanic equivalent to sea ice brines showed that the physical concentration of seawater ions and the changes in ikaite solubility as a function of salinity and temperature, both inherent in the sea ice system, would be insufficient to drive the emergent brines to ikaite supersaturation and precipitation in sea ice down to -8 °C. The loss of dissolved inorganic carbon to the gas phase of sea ice and to sympagic autotrophs are two independent mechanisms which, in nature, could prompt the brine CO2 system towards ikaite supersaturation and precipitation. Under these conditions, the steady state precipitation rate of ikaite was found to be fast enough for rapid formation within short time scales (days to weeks) in sea ice. The observed ikaite dissolution kinetics were also found conducive to short turn-over time scales of a few hours to a few days in corrosive solutions, such as surface seawater.

Pycnonuclear 12C+12C reaction at zero temperature

International Nuclear Information System (INIS)

Gasques, L R; Beard, M; Chamon, L C; Wiescher, M

2005-01-01

We present pycnonuclear reaction calculations for a one-component ionic crystal at zero temperature considering different theoretical approaches. The rates depend directly on the determination of the astrophysical S-factor at low energies, which has been obtained through the barrier penetration formalism. A totally parameter-free model for the real part of the nuclear interaction has been employed in the calculation of 12 C+ 12 C fusion cross sections

Ising ferromagnet: zero-temperature dynamic evolution

International Nuclear Information System (INIS)

Oliveira, P M C de; Newman, C M; Sidoravicious, V; Stein, D L

2006-01-01

The dynamic evolution at zero temperature of a uniform Ising ferromagnet on a square lattice is followed by Monte Carlo computer simulations. The system always eventually reaches a final, absorbing state, which sometimes coincides with a ground state (all spins parallel), and sometimes does not (parallel stripes of spins up and down). We initiate here the numerical study of 'chaotic time dependence' (CTD) by seeing how much information about the final state is predictable from the randomly generated quenched initial state. CTD was originally proposed to explain how nonequilibrium spin glasses could manifest an equilibrium pure state structure, but in simpler systems such as homogeneous ferromagnets it is closely related to long-term predictability and our results suggest that CTD might indeed occur in the infinite volume limit

Topological properties of function spaces $C_k(X,2)$ over zero-dimensional metric spaces $X$

OpenAIRE

Gabriyelyan, S.

2015-01-01

Let $X$ be a zero-dimensional metric space and $X'$ its derived set. We prove the following assertions: (1) the space $C_k(X,2)$ is an Ascoli space iff $C_k(X,2)$ is $k_\\mathbb{R}$-space iff either $X$ is locally compact or $X$ is not locally compact but $X'$ is compact, (2) $C_k(X,2)$ is a $k$-space iff either $X$ is a topological sum of a Polish locally compact space and a discrete space or $X$ is not locally compact but $X'$ is compact, (3) $C_k(X,2)$ is a sequential space iff $X$ is a Pol...

NdFeB magnets with zero temperature coefficient of induction

International Nuclear Information System (INIS)

Ma, B.M.; Narasimhan, K.S.V.L.; Hurt, J.C.

1986-01-01

Temperature compensation for the induction of NdFeB type magnets has been investigated. A computer assisted alloy selection method was adopted to identify composition of zero temperature coefficient of induction over -50 to 200 0 C. Selected alloys were processed into magnet by the conventional powder metallurgy method. The experimental temperature coefficient on the sintered magnet correlated with the prediction satisfactory. Holmium is an essential ingredient required for temperature compensation of NdFeB magnets. A magnet, (Nd/sub 0.23/Ho/sub 0.64/Dy/sub 0.13/)/sub 15/Fe/sub 79/B/sub 6/ with B/sub r/ of 7,700 Gauss, H/sub c/ of 7,700 Oe, H/sub ci/ of 20,600 Oe, Bh/sub max/ of 14.8 MGOe and temperature coefficient of -0.029% per 0 C over -50 to +150 was obtained

Non-zero intercept frequency : an accurate method to determine the integral temperature of li-ion batteries

NARCIS (Netherlands)

Raijmakers, L.H.J.; Danilov, D.L.; van Lammeren, J.; Lammers, T.; Bergveld, H.J.; Notten, P.H.L.

2016-01-01

A new impedance-based approach is introduced in which the integral battery temperature is related to other frequencies than the recently developed zero-intercept frequency (ZIF). The advantage of the proposed non-zero-intercept frequency (NZIF) method is that measurement interferences, resulting

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.

Novel Zero-Heat-Flux Deep Body Temperature Measurement in Lower Extremity Vascular and Cardiac Surgery.

Science.gov (United States)

Mäkinen, Marja-Tellervo; Pesonen, Anne; Jousela, Irma; Päivärinta, Janne; Poikajärvi, Satu; Albäck, Anders; Salminen, Ulla-Stina; Pesonen, Eero

2016-08-01

The aim of this study was to compare deep body temperature obtained using a novel noninvasive continuous zero-heat-flux temperature measurement system with core temperatures obtained using conventional methods. A prospective, observational study. Operating room of a university hospital. The study comprised 15 patients undergoing vascular surgery of the lower extremities and 15 patients undergoing cardiac surgery with cardiopulmonary bypass. Zero-heat-flux thermometry on the forehead and standard core temperature measurements. Body temperature was measured using a new thermometry system (SpotOn; 3M, St. Paul, MN) on the forehead and with conventional methods in the esophagus during vascular surgery (n = 15), and in the nasopharynx and pulmonary artery during cardiac surgery (n = 15). The agreement between SpotOn and the conventional methods was assessed using the Bland-Altman random-effects approach for repeated measures. The mean difference between SpotOn and the esophageal temperature during vascular surgery was+0.08°C (95% limit of agreement -0.25 to+0.40°C). During cardiac surgery, during off CPB, the mean difference between SpotOn and the pulmonary arterial temperature was -0.05°C (95% limits of agreement -0.56 to+0.47°C). Throughout cardiac surgery (on and off CPB), the mean difference between SpotOn and the nasopharyngeal temperature was -0.12°C (95% limits of agreement -0.94 to+0.71°C). Poor agreement between the SpotOn and nasopharyngeal temperatures was detected in hypothermia below approximately 32°C. According to this preliminary study, the deep body temperature measured using the zero-heat-flux system was in good agreement with standard core temperatures during lower extremity vascular and cardiac surgery. However, agreement was questionable during hypothermia below 32°C. Copyright © 2016 Elsevier Inc. All rights reserved.

Mass current in 3He - A: Some exact representations and their London limit near zero temperature

International Nuclear Information System (INIS)

Malyshev, C.

1995-09-01

New representations for normal Green's function of the superfluid A-phase of helium-3 are obtained by an exact solution of the Dyson-Gor'kov equation. These representations result in new formulae for the mass current j-vector near zero temperature. Specific limiting cases for j-vector such ast the limit of lowest order in gradients, following the limit of zero temperature, and vice versa, are investigated. It is shown that the mass current previously known as j-vector = j-vector 0 , where j-vector 0 is an expression of first order in gradients, should be treated as a ''quasiclassical'' object in view of the approximations chosen. The parameter 1/χ implying the ''quasiclassics'', is a small quantity, as the London limit condition holds. Expansion of j-vector in powers of 1/χ is considered and first corrections to j-vector 0 are obtained at zero temperature, for two gauges of the order parameter. (author). 26 refs

On the zero temperature limit of the Kubo-transformed quantum time correlation function

Science.gov (United States)

Hernández de la Peña, Lisandro

2014-04-01

The zero temperature limit of several quantum time correlation functions is analysed. It is shown that while the canonical quantum time correlation function retains the full dynamical information as temperature approaches zero, the Kubo-transformed and the thermally symmetrised quantum time correlation functions lose all dynamical information at this limit. This is shown to be a consequence of the projection onto the ground state, via the limiting process of the quantities ? and ?, either together as a product, or separately. Although these findings would seem to suggest that finite-temperature methods commonly used to estimate Kubo correlation functions would be incapable of retaining any ground state dynamics, we propose a route for recovering in principle all dynamical information at the ground state. It is first shown that the usual frequency space relation between canonical and Kubo correlation functions also holds for microcanonical time correlation functions. Since the Kubo-transformed microcanonical correlation function can be obtained from the usual finite-temperature function by including a projection onto the corresponding microcanonical ensemble, finite-temperature methods, properly modified to incorporate such a constraint, can be used to capture full quantum dynamics at any arbitrary energy state, including the ground state. This approach is illustrated with the application of centroid dynamics to the ground state dynamics of the harmonic oscillator.

Zero temperature landscape of the random sine-Gordon model

International Nuclear Information System (INIS)

Sanchez, A.; Bishop, A.R.; Cai, D.

1997-01-01

We present a preliminary summary of the zero temperature properties of the two-dimensional random sine-Gordon model of surface growth on disordered substrates. We found that the properties of this model can be accurately computed by using lattices of moderate size as the behavior of the model turns out to be independent of the size above certain length (∼ 128 x 128 lattices). Subsequently, we show that the behavior of the height difference correlation function is of (log r) 2 type up to a certain correlation length (ξ ∼ 20), which rules out predictions of log r behavior for all temperatures obtained by replica-variational techniques. Our results open the way to a better understanding of the complex landscape presented by this system, which has been the subject of very many (contradictory) analysis

Gravity and Zero Point Energy

Science.gov (United States)

Massie, U. W.

When Planck introduced the 1/2 hv term to his 1911 black body equation he showed that there is a residual energy remaining at zero degree K after all thermal energy ceased. Other investigators, including Lamb, Casimir, and Dirac added to this information. Today zero point energy (ZPE) is accepted as an established condition. The purpose of this paper is to demonstrate that the density of the ZPE is given by the gravity constant (G) and the characteristics of its particles are revealed by the cosmic microwave background (CMB). Eddies of ZPE particles created by flow around mass bodies reduce the pressure normal to the eddy flow and are responsible for the force of gravity. Helium atoms resonate with ZPE particles at low temperature to produce superfluid helium. High velocity micro vortices of ZPE particles about a basic particle or particles are responsible for electromagnetic forces. The speed of light is the speed of the wave front in the ZPE and its value is a function of the temperature and density of the ZPE.

A 20mK temperature sensor

International Nuclear Information System (INIS)

Wang, N.; Sadoulet, B.; Shutt, T.

1987-11-01

We are developing a 20mK temperature sensor made of neutron transmutation doped (NTD) germanium for use as a phonon detector in a dark matter search. We find that NTD germanium thermistors around 20mK have resistances which are a strong function of temperature, and have sufficient sensitivity to eventually reach a base line rms energy fluctuation of 6eV at 25mK. Further work is needed to understand the extreme sensitivity of the thermistors to bias power. 13 refs., 18 figs

A review of TLD's zero-count based on temperature and radiation history of them

Science.gov (United States)

Tunçel, Nina; Karakuş, İsmail; Dündar, Ertuğrul; Toykan Çiflikçi, Özlem

2017-09-01

In order to review the background value of a group of TLD-100, the zero-count values were collected from the first reading and after seven years after using them in experimental irradiations. The zero-counts for these two conditions were collected, as well as the dependence of temperature and radiation history of this group was evaluated. This study recommended that after frequently irradiation of TLDs the rearrangement for obtaining zero-count value must be performed before using TLDs in a new irradiation examination. Regarding on memory of radiation and thermal history, the sensitivity can change after receiving a large dose of radiation and undergoing readout. Additional annealing would be necessary to restore the original sensitivity. TLDs must be used under reproducible conditions to obtain consistent results.

In-situ investigation of martensite formation in AISI 52100 bearing steel at sub-zero Celsius temperature

DEFF Research Database (Denmark)

Villa, Matteo; Hansen, Mikkel Fougt; Pantleon, Karen

2013-01-01

Martensite formation in AISI 52100 bearing steel at sub-zero Celsius temperature was investigated with Vibrating Sample Magnetometry. The investigation reports the stabilization of retained austenite in quenched samples during storage at room temperature and reveals the thermally activated nature...

Quantum confinement of zero-dimensional hybrid organic-inorganic polaritons at room temperature

Science.gov (United States)

Nguyen, H. S.; Han, Z.; Abdel-Baki, K.; Lafosse, X.; Amo, A.; Lauret, J.-S.; Deleporte, E.; Bouchoule, S.; Bloch, J.

2014-02-01

We report on the quantum confinement of zero-dimensional polaritons in perovskite-based microcavity at room temperature. Photoluminescence of discrete polaritonic states is observed for polaritons localized in symmetric sphere-like defects which are spontaneously nucleated on the top dielectric Bragg mirror. The linewidth of these confined states is found much sharper (almost one order of magnitude) than that of photonic modes in the perovskite planar microcavity. Our results show the possibility to study organic-inorganic cavity polaritons in confined microstructure and suggest a fabrication method to realize integrated polaritonic devices operating at room temperature.

Quantum confinement of zero-dimensional hybrid organic-inorganic polaritons at room temperature

International Nuclear Information System (INIS)

Nguyen, H. S.; Lafosse, X.; Amo, A.; Bouchoule, S.; Bloch, J.; Han, Z.; Abdel-Baki, K.; Lauret, J.-S.; Deleporte, E.

2014-01-01

We report on the quantum confinement of zero-dimensional polaritons in perovskite-based microcavity at room temperature. Photoluminescence of discrete polaritonic states is observed for polaritons localized in symmetric sphere-like defects which are spontaneously nucleated on the top dielectric Bragg mirror. The linewidth of these confined states is found much sharper (almost one order of magnitude) than that of photonic modes in the perovskite planar microcavity. Our results show the possibility to study organic-inorganic cavity polaritons in confined microstructure and suggest a fabrication method to realize integrated polaritonic devices operating at room temperature

ZERO-FIELD NUCLEAR MAGNETIC RESONANCE FOR STUDY OF ANTIFERROMAGNETIC PROPERTIES OF FeF3 MATERIALS

Directory of Open Access Journals (Sweden)

G. R. F. Suwandi

2016-01-01

Full Text Available Nuclear Magnetic Resonance (NMR has been used as a research tool in many fields. In this study, the magnetic properties, especially anti-ferromagnetic properties of FeF3 materials were investigated. Zero-field custom-built NMR method was used to investigate the anti-ferromagnetic properties in the materials. Experiments have been carried out by varying the sample temperatures from 8 K to 220 K. Ordinary spin echo pulse sequence 90⁰RF–τ–180⁰RF were used. Using Fast Fourier Transform, the signals in NMR spectrum were analyzed and the peak showed the resonance frequency. The result showed that resonance frequencies decrease with increasing in temperature. The frequency of the spectrum was around 85.41 MHz in the zero-temperature limit, and this corresponds with Fe hyperfine field at zero-temperature limit was 2.14 T. The temperature dependence of the local magnetization does not fit T2 Bloch’s Law very well. Instead, it fits the exponential form having an energy gap in the dispersion relation of the spin wave. It is obtained from the result that FeF3 is antiferromagnetic materials with energy gap of 11.466 meV and anisotropy energy of 1.045 meV.Nuclear Magnetic Resonance (NMR telah banyak digunakan sebagai “research tool” pada berbagai bidang kajian di fisika. Pada studi ini, akan dilakukan eksperimen untuk menguji sifat magnetik, khususnya antiferromagnetik pada material FeF3. Telah dilakukan eksperimen dengan memvariasikan temperatur pada sampel dari 8 K hingga 220 K. Pulse sequence yang digunakan adalah 90⁰RF–τ–180⁰RF. Dengan memanfaatkan Fast Fourier Transform, sinyal echo ini dapat dianalisis dalam bentuk spektrum NMR dengan puncak spektrum menunjukkan frekuensi resonansinya. Diperoleh bahwa frekuensi resonansi akan menurun seiring dengan kenaikan temperatur. Posisi frekuensi pada temperatur 0 K adalah sebesar 85,41 MHz, hal ini memperlihatkan bahwa medan hyperfine dari Fe sebesar 2,14 T pada temperatur 0 K. Kurva

The 77 K operation of a multi-resonant power converter

Science.gov (United States)

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

1995-01-01

The liquid-nitrogen temperature (77 K) operation of a 55 W, 200 kHz, 48/28 V zero-voltage switching multi-resonant dc/dc converter designed with commercially available components is reported. Upon dipping the complete converter (power and control circuits) into liquid-nitrogen, the converter performance improved as compared to the room-temperature operation. The switching frequency, resonant frequency, and the characteristic impedance did not change significantly. Accordingly, the zero-voltage switching was maintained from no-load to full-load for the specified line variations. Cryoelectronics can provide high density power converters, especially for high power applications.

Zero thermal expansion in NaZn13-type La(Fe,Si)13 compounds.

Science.gov (United States)

Wang, Wei; Huang, Rongjin; Li, Wen; Tan, Jie; Zhao, Yuqiang; Li, Shaopeng; Huang, Chuanjun; Li, Laifeng

2015-01-28

A zero thermal expansion material in a pure form of NaZn13-type La(Fe,Si)13 was fabricated. Through optimizing the chemical composition, an isotropic zero thermal expansion material is achieved. The obtained materials exhibit a low expansion of |α| linear thermal expansion) over a broad temperature range (15-150 K). The present study indicates that the thermal expansion behavior of the NaZn13-type La(Fe,Si)13 compounds depends mainly on the content of Si element. This new material is desirable in many fields of industry as a reliable and low-cost zero thermal expansion material.

Spin glass: thermal properties and characterization of the ± J Sherrington-Kirkpatrick model partition function zeros

International Nuclear Information System (INIS)

Faria, A.C. de.

1990-01-01

A detailed study of the S-K model through the analysis of the zeros of the partition function in the complex temperature plane is performed. By the exact way, the notable thermodynamical properties of the system to a variety of the length (N=5→25 spins) are calculated, using only standards concepts (without the use of tricks like that of replicas). Dilute models had been also considered. The principal result of this work is the characterization of the zeros of the partition function of the S-K model. (author)

Study of instantaneous unsteady heat transfer in a rapid compression-expansion machine using zero dimensional k- ε turbulence model

International Nuclear Information System (INIS)

Bakhshan, Y.; Karim, G. A.; Mansouri, S. H.

2003-01-01

In this investigation, the instantaneous unsteady heat transfer within a pneumatically driven rapid compression-expansion machine that offers simple, well-controlled and known boundary conditions was studied. Values of the instantaneous apparent overall heat flux from the cylinder gas to the wall surfaces were calculated using a thermodynamics analysis of the experimentally measured pressure and volume temporal development. Corresponding heat flux values were also calculated through the application of a zero-dimensional k- ε turbulence model the characteristic velocity is a contribution of turbulence kinetic energy, mean kinetic energy of charged air into cylinder and piston motion for the calculation of Reynolds, Nusselt and Prandtl numbers. Comparison of the zero-dimensional k- ε turbulence model prediction with experimental data shows good agreement for all compression ratios

Photon polarization tensor in the light front field theory at zero and finite temperatures

International Nuclear Information System (INIS)

Silva, Charles da Rocha; Perez, Silvana; Strauss, Stefan

2012-01-01

Full text: In recent years, light front quantized field theories have been successfully generalized to finite temperature. The light front frame was introduced by Dirac , and the quantization of field theories on the null-plane has found applications in many branches of physics. In order to obtain the thermal contribution, we consider the hard thermal loop approximation. This technique was developed by Braaten and Pisarski for the thermal quantum field theory at equal times and is particularly useful to extract the leading thermal contributions to the amplitudes in perturbative quantum field theories. In this work, we consider the light front quantum electrodynamics in (3+1) dimensions and evaluate the photon polarization tensor at one loop for both zero and finite temperatures. In the first case, we apply the dimensional regularization method to extract the finite contribution and find the transverse structure for the amplitude in terms of the light front coordinates. The result agrees with one-loop covariant calculation. For the thermal corrections, we generalize the hard thermal loop approximation to the light front and calculate the dominant temperature contribution to the polarization tensor, consistent with the Ward identity. In both zero as well as finite temperature calculations, we use the oblique light front coordinates. (author)

Yang-Lee zeros for a Potts model of helix-coil transition with nontrivial topology

International Nuclear Information System (INIS)

Ananikian, N.; Ananikyan, L.; Artuso, R.; Sargsyan, K.

2007-07-01

The Yang-Lee partition function zeros of the Q-state Potts model on a zigzag ladder are studied by a transfer-matrix approach. This Q-state model has a non-trivial topology induced by three-site interactions on a zigzag ladder and is proposed as a description of helix-coil transition in homo-polymers. The Yang-Lee zeros are associated to complex values of the solvent-related coupling constant K (magnetic field) and they are exactly derived for arbitrary values of the system parameters: Q, J (coupling constant of hydrogen binding) and temperature. It is shown that there is only a quasi-phase transition for all temperatures. The densities of the Yang-Lee zeros are singular at the edge singularity points and the critical exponent σ = -1/2. (author)

Germanium thermometers in the temperature range .1000K to 4.20K

International Nuclear Information System (INIS)

Hsieh, S.Y.; Sanchez, D.H.

1974-01-01

The sensitivity characteristics of two germanium thermometers that proved to be convenient sensors in the temperature range from .100 0 K to 4.2 0 K, are described. Their resistances change from about 8 x 10 5 ohms at .100 0 K to about 100 ohms at 4.2 0 K. The calibration curves were fitted to natural spline functions of order 3 in the whole range of temperatures. These functions give less than half millidegree standard dispersion against 15 millidegree standard dispersion when usual polynomial interpolations are used. It is discussed what spline functions are, and compare the goodness of spline interpolation with polynomial methods [pt

Non-zero temperature two-mode squeezing for time-dependent two-level systems

International Nuclear Information System (INIS)

Aliaga, J.; Gruver, J.L.; Proto, A.N.; Cerdeira, H.A.

1994-01-01

A Maximum Entropy Principle density matrix method, valid for systems with temperature different from zero, is presented making it possible two-mode squeezed states in two-level systems with relevant operators and Hamiltonian connected with O(3,2). A method which allows one to relate the appearance of squeezing to the relevant operators, included in order to define the density matrix of the system is given. (author). 14 refs, 1 fig

Equilibrium shape of (4)He crystal under zero gravity below 200 mK.

Science.gov (United States)

Takahashi, Takuya; Ohuchi, Haruka; Nomura, Ryuji; Okuda, Yuichi

2015-10-01

Equilibrium crystal shape is the lowest energy crystal shape that is hardly realized in ordinary crystals because of their slow relaxation. (4)He quantum crystals in a superfluid have been expected as unique exceptions that grow extremely fast at very low temperatures. However, on the ground, gravity considerably deforms the crystals and conceals the equilibrium crystal shape, and thus, gravity-free environment is needed to observe the equilibrium shape of (4)He. We report the relaxation processes of macroscopic (4)He crystals in a superfluid below 200 mK under zero gravity using a parabolic flight of a jet plane. When gravity was removed from a gravity-flattened (4)He crystal, the crystal rapidly transformed into a shape with flat surfaces. Although the relaxation processes were highly dependent on the initial condition, the crystals relaxed to a nearly homothetic shape in the end, indicating that they were truly in an equilibrium shape minimizing the interfacial free energy. Thanks to the equilibrium shape, we were able to determine the Wulff's origin and the size of the c-facet together with the vicinal surface profile next to the c-facet. The c-facet size was extremely small in the quantum crystals, and the facet-like flat surfaces were found to be the vicinal surfaces. At the same time, the interfacial free energy of the a-facet and s-facet was also obtained.

Oxygen plasma effects on zero resistance behavior of Yb,Er-doped YBCO (123) based superconductors

Energy Technology Data Exchange (ETDEWEB)

Schaefer, Helmut; Rathmann, Dirk [Department of Physics, Biophysics, and Photosynthesis, Freie Universitaet Berlin (Germany); Banko, Franziska; Steinhart, Martin [Physical Chemistry, Institute of Chemistry of New Materials, University of Osnabrueck (Germany); Nordmann, Joerg; Voss, Benjamin [Inorganic Chemistry, Institute of Chemistry of New Materials, University of Osnabrueck (Germany); Walder, Lorenz [Organic Chemistry, Molecular Electrochemistry, Institute of Chemistry of New Materials, University of Osnabrueck (Germany)

2014-08-15

Rare-earth doped YBa{sub 2}Cu{sub 3}O{sub 7-δ} samples were synthesized starting from the corresponding oxides Y{sub 2}O{sub 3}, Yb{sub 2}O{sub 3}, Er{sub 2}O{sub 3}, CuO as well as Ba(OH){sub 2} by heating to 950 C under air. The doping concentrations were adjusted to 15 % Yb, 7 % Er and 20 % Yb, 15 % Er, respectively, with respect to the yttrium content. The orthogonal phased (123) YBCO ceramics were exposed to an oxygen plasma for 140 and 380 min. Zero resistance temperature (T{sub c,0}) was determined by measuring the resistivity-temperature dependence using a classical four point measurement approach. Under optimal conditions with respect to the material composition and the oxygen treatment an unusual high zero resistance temperature of 97.5 K (T{sub c,onset} ∼ 101 K) was achieved. This represents an increase of T{sub c,0} by 7.5 K. The oxygen treatment could not be monitored by IR spectroscopy, X-ray fluorescence spectroscopy, and X-ray powder diffraction. The results showed good reproducibility. (Copyright copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

A new estimate of the Khirzhnits corrections to the zero temperature Thomas-Fermi equation-of-state

International Nuclear Information System (INIS)

Szichman, H.; Krumbein, A.D.; Eliezer, S.

1984-09-01

A method is proposed for estimating the zero temperature limit of the Khirzhnits corrections to the Thomas-Fermi equation-of-state by extrapolation of the finite-temperature results. The cold curves so obtained for Ti, Fe, Cu and Ta are compared with experimental results as well as with those calculated using other variations of the Thomas-Fermi model

Vibrational zero point energy for H-doped silicon

Science.gov (United States)

Karazhanov, S. Zh.; Ganchenkova, M.; Marstein, E. S.

2014-05-01

Most of the studies addressed to computations of hydrogen parameters in semiconductor systems, such as silicon, are performed at zero temperature T = 0 K and do not account for contribution of vibrational zero point energy (ZPE). For light weight atoms such as hydrogen (H), however, magnitude of this parameter might be not negligible. This Letter is devoted to clarify the importance of accounting the zero-point vibrations when analyzing hydrogen behavior in silicon and its effect on silicon electronic properties. For this, we estimate the ZPE for different locations and charge states of H in Si. We show that the main contribution to the ZPE is coming from vibrations along the Si-H bonds whereas contributions from other Si atoms apart from the direct Si-H bonds play no role. It is demonstrated that accounting the ZPE reduces the hydrogen formation energy by ˜0.17 eV meaning that neglecting ZPE at low temperatures one can underestimate hydrogen solubility by few orders of magnitude. In contrast, the effect of the ZPE on the ionization energy of H in Si is negligible. The results can have important implications for characterization of vibrational properties of Si by inelastic neutron scattering, as well as for theoretical estimations of H concentration in Si.

Direct writing of room temperature and zero field skyrmion lattices by a scanning local magnetic field

KAUST Repository

Zhang, Senfu; Zhang, Junwei; Zhang, Qiang; Barton, Craig; Neu, Volker; Zhao, Yuelei; Hou, Zhipeng; Wen, Yan; Gong, Chen; Kazakova, Olga; Wang, Wenhong; Peng, Yong; Garanin, Dmitry A.; Chudnovsky, Eugene M.; Zhang, Xixiang

2018-01-01

Magnetic skyrmions are topologically protected nanoscale spin textures exhibiting fascinating physical behaviors. Recent observations of room temperature skyrmions in sputtered multilayer films are an important step towards their use in ultra-low power devices. Such practical applications prefer skyrmions to be stable at zero magnetic fields and room temperature. Here, we report the creation of skyrmion lattices in Pt/Co/Ta multilayers by a scanning local field using magnetic force microscopy tips. We also show that those newly created skyrmion lattices are stable at both room temperature and zero fields. Lorentz transmission electron microscopy measurements reveal that the skyrmions in our films are of Néel-type. To gain a deeper understanding of the mechanism behind the creation of a skyrmion lattice by the scanning of local fields, we perform micromagnetic simulations and find the experimental results to be in agreement with our simulation data. This study opens another avenue for the creation of skyrmion lattices in thin films.

Direct writing of room temperature and zero field skyrmion lattices by a scanning local magnetic field

KAUST Repository

Zhang, Senfu

2018-03-29

Magnetic skyrmions are topologically protected nanoscale spin textures exhibiting fascinating physical behaviors. Recent observations of room temperature skyrmions in sputtered multilayer films are an important step towards their use in ultra-low power devices. Such practical applications prefer skyrmions to be stable at zero magnetic fields and room temperature. Here, we report the creation of skyrmion lattices in Pt/Co/Ta multilayers by a scanning local field using magnetic force microscopy tips. We also show that those newly created skyrmion lattices are stable at both room temperature and zero fields. Lorentz transmission electron microscopy measurements reveal that the skyrmions in our films are of Néel-type. To gain a deeper understanding of the mechanism behind the creation of a skyrmion lattice by the scanning of local fields, we perform micromagnetic simulations and find the experimental results to be in agreement with our simulation data. This study opens another avenue for the creation of skyrmion lattices in thin films.

Direct writing of room temperature and zero field skyrmion lattices by a scanning local magnetic field

Science.gov (United States)

Zhang, Senfu; Zhang, Junwei; Zhang, Qiang; Barton, Craig; Neu, Volker; Zhao, Yuelei; Hou, Zhipeng; Wen, Yan; Gong, Chen; Kazakova, Olga; Wang, Wenhong; Peng, Yong; Garanin, Dmitry A.; Chudnovsky, Eugene M.; Zhang, Xixiang

2018-03-01

Magnetic skyrmions are topologically protected nanoscale spin textures exhibiting fascinating physical behaviors. Recent observations of room temperature skyrmions in sputtered multilayer films are an important step towards their use in ultra-low power devices. Such practical applications prefer skyrmions to be stable at zero magnetic fields and room temperature. Here, we report the creation of skyrmion lattices in Pt/Co/Ta multilayers by a scanning local field using magnetic force microscopy tips. We also show that those newly created skyrmion lattices are stable at both room temperature and zero fields. Lorentz transmission electron microscopy measurements reveal that the skyrmions in our films are of Néel-type. To gain a deeper understanding of the mechanism behind the creation of a skyrmion lattice by the scanning of local fields, we perform micromagnetic simulations and find the experimental results to be in agreement with our simulation data. This study opens another avenue for the creation of skyrmion lattices in thin films.

Transverse- and zero-field μSR [muon-spin-rotation] investigation of magnetism and superconductivity in (Y1-xPrx)Ba2Cu3O7

International Nuclear Information System (INIS)

Cooke, D.W.; Jahan, M.S.; Kwok, R.S.; Lichti, R.L.; Adams, T.R.; Boekema, C.; Dawson, W.K.; Kebede, A.; Schwegler, J.; Crow, J.E.; Mihalsin, T.

1990-01-01

Zero-field muon-spin-rotation (μSR) measurements on (Y 1-x Pr x )Ba 2 Cu 3 O 7 [x = 1.0, 0.8, 0.6, and 0.54] show evidence for antiferromagnetic ordering of the Cu moments within the Cu--O planes, with Neel temperatures 285,220, 35, 30, and 20 K respectively. For x = 1.0 the local muon magnetic field is ∼16 mT, but decreases to ∼12 mT at 17 K, due to additional magnetic ordering. The zero-field data, in conjunction with transport data, allow construction of a complete diagram for this system. Transverse-field (1 kOe) μSR data for x = 0.2 (T c = 75 K) show that the muon depolarization is determined primarily by the Cu nuclear moments for T>T c . Fitting the superconducting-state data to a BCS model yields an extrapolated zero-temperature magnetic penetration depth of 2170 angstrom. 9 refs., 3 figs

X-ray and neutron powder investigations of pure and yttrium doped CeO2 at temperatures up to 1600 K

International Nuclear Information System (INIS)

Berber, K.; Martin, U.; Mursic, Z.; Schneider, J.; Boysen, H.; Frey, F.

1991-01-01

Ceria, CeO 2 powders and sintermaterials with different amounts of yttria, Y 2 O 3 , (0-10 mole %) were investigated up to 1600 K by X-ray and neutron powder diffraction. In the sample with 3 mole % yttria the onset of a solid-state reaction or a kind of phase change at 900 K is indicated by a change of the lattice expansion coefficient and by an increase of the slope of the B iso (T) curve. Microstrains are present in the sintered material above 900 K. Anharmonic contributions to the temperature factor of the oxygens become significant at higher temperatures. We deduce from a non-zero part B T ≠0 some static disorder within the O-sublattice. Pdf-maps of the oxygens show clearly deformations of the 'normal' isotropic behaviour, but exceptional smearing out or even closed pathways are not observed. Thus, the superior anionic conductivity of this material is not reflected by the features of the averaged structure. It is most likely due to a disordered 'interface-structure' between ordered domains. A temperature dependent 'structured' background scattering supports this conclusion. (author) 6 figs., 9 refs

Neutron inelastic sattering from liquid 3He at 40 mK and at 1.2 K

International Nuclear Information System (INIS)

Skoeld, K.; Pelizzari, C.A.

1978-01-01

In a previous neutron scattering experiment on 3 He at T = 15 mK the present authors observed two peaks in the scattering function which were identified as the zero sound mode and the spin-fluctuation peak respectively. These results are different from those obtained by others at T = 0.63 K in which case no such structure was observed. In order to determine whether this discrepancy is due to the difference in the temperature of the two experiments, measurements have now been made at T = 40 mK and at T = 1.2 K. These results show that the two-peak structure persists at the higher temperature although measurable broadening is observed in the spin-fluctuation part of the spectrum. (author)

Enhanced temperature-independent magnetoresistance below the ...

Indian Academy of Sciences (India)

The film exhibits a large nearly temperature-independent magnetoresistance around 99% in the temperature regime below p. The zero field-cooled (ZFC) and field-cooled (FC) magnetization data at 50 Oe shows irreversibility between the ZFC and FC close to the ferromagnetic transition temperature c = 250 K. The ZFC ...

Temperature dependence of thermal expansion of cadmium sulfide in the temperature range 20 - 820 K

International Nuclear Information System (INIS)

Oskotskij, V.S.; Kobyakov, I.B.; Solodukhin, A.V.

1980-01-01

The linear thermal expansion of cadmium sulfide is measured perpendicularly (α 1 ) and parallelly (α 2 ) to the hexagonal axis in the temperature range from 20 to 820 K. Anisotropy is low at up to 80 K; rises at higher temperatures; at 3OO K α 1 /α 3 ratio is 1.8; at 820 K, 2.4. Heat expansion is negative at temperatures lower than 104.5 K(α 1 ) and 126.0 K(α 2 ). It achieves the minimum at 43.6 K (α 1 ) and 52.5K (α 3 ). The theory of heat expansion is plotted in the Debue, approximation and cadmium sulfide is considered as an isotope crystal with average elastic constants. Two parameters of the theory are determined by the position and value of the minimum of volumetric thermal expansion of the model isotope crystal. The theoretic curve agrees well with the experimental one at temperatures up to 160 K, i.e in the range of applicability of the Debue approximation and the isotropic model

Constraining the Natural MSSM through tunneling to color-breaking vacua at zero and non-zero temperature

Directory of Open Access Journals (Sweden)

J.E. Camargo-Molina

2014-10-01

Full Text Available We re-evaluate the constraints on the parameter space of the minimal supersymmetric standard model from tunneling to charge- and/or color-breaking minima, taking into account thermal corrections. We pay particular attention to the region known as the Natural MSSM, where the masses of the scalar partners of the top quarks are within an order of magnitude or so of the electroweak scale. These constraints arise from the interaction between these scalar tops and the Higgs fields, which allows the possibility of parameter points having deep charge- and color-breaking true vacua. In addition to requiring that our electroweak-symmetry-breaking, yet QCD- and electromagnetism-preserving vacuum has a sufficiently long lifetime at zero temperature, also demanding stability against thermal tunneling further restricts the allowed parameter space.

Statistics of energy levels and zero temperature dynamics for deterministic spin models with glassy behaviour

NARCIS (Netherlands)

Degli Esposti, M.; Giardinà, C.; Graffi, S.; Isola, S.

2001-01-01

We consider the zero-temperature dynamics for the infinite-range, non translation invariant one-dimensional spin model introduced by Marinari, Parisi and Ritort to generate glassy behaviour out of a deterministic interaction. It is argued that there can be a large number of metastable (i.e.,

Thermodynamic Temperatures of the Triple Points of Mercury and Gallium and in the Interval 217 K to 303 K

OpenAIRE

Moldover, M. R.; Boyes, S. J.; Meyer, C. W.; Goodwin, A. R. H.

1999-01-01

We measured the acoustic resonance frequencies of an argon-filled spherical cavity and the microwave resonance frequencies of the same cavity when evacuated. The microwave data were used to deduce the thermal expansion of the cavity and the acoustic data were fitted to a temperature-pressure surface to deduce zero-pressure speed-of-sound ratios. The ratios determine (T?T 90), the difference between the Kelvin thermodynamic temperature T and the temperature on the International Temperature Sca...

Decay of the vortex tangle at zero temperature and quasiclassical turbulence

International Nuclear Information System (INIS)

Nemirovskii, Sergej K.

2013-01-01

We review and analyze a series of works, both experimental and numerical and theoretical, dealing with the decay of quantum turbulence at zero temperature. Free decay of the vortex tangle is a key argument in favor of the idea that a chaotic set of quantum vortices can mimic classical turbulence, or at least reproduce many of the basic features. The corresponding topic is referred as the quasiclassical turbulence. Appreciating significance of the challenging problem of classical turbulence it can be expressed that the idea to study it in terms of quantized line is indeed very important and may be regarded as a breakthrough. For this reason, the whole theory, together with the supporting experimental results and numerical simulations should be carefully scrutinized. One of the main arguments, supporting the idea of quasiclassical turbulence is the fact that vortex tangle decays at zero temperature, when the mutual friction is absent. Since all other possible mechanisms of dissipation of the vortex energy, discussed in literature, are related to the small scales, it is natural to suggest that the Kolmogorov cascade takes place with the flow of the energy in space of scales, just like as in the classical turbulence. In the present work we discuss an alternative mechanism of decay of the vortex tangle, which is not associated with dissipation at small scales. This mechanism is a diffusive-like spreading of the vortex tangle due to evaporation of small vortex loops. We discuss a number of experiments and numerical simulations, considering them from the point of view of alternative mechanism.

Temperature dependence of muonium spin exchange with O2 in the range 88 K to 478 K

International Nuclear Information System (INIS)

Senba, M.; Garner, D.M.; Arseneau, D.J.; Fleming, D.G.

1984-01-01

The authors have extended an earlier study of the spin exchange reactions of Mu with O 2 in the range 295 K to 478 K, to a low temperature region down to 88 K. From 135 K to 296 K, the spin depolarization rate constant was found to vary according to the relative velocity of the colliding species, which indicates that the spin exchange cross section of Mu-O 2 is temperature independent in this range. However, it was found that below 105 K and above 400 K, the spin depolarization rate constant tends to have stronger temperature dependences. (Auth.)

Model of discontinuous plastic flow at temperature close to absolute zero

CERN Document Server

Marcinek, Dawid Jarosław; Sgobba, Stefano

In the present study cryogenic tensile tests performed on different materials (316LN, JK2LB) were used. The discontinuous plastic flow phenomenon was analysed, in order to develop a constitutive model of serrated yielding as a support for analysis of structural materials at low temperatures. Devices and structures, cooled be means of liquid helium, operate at the temperatures equal or lower than 4.2 K, which for the examined materials is below the transition threshold between screw and edge dislocations. It is considered a threshold for the appearance of DPF consisting in cyclic drop of load followed by deformation jumps and generation of heat. Temperature oscillations resulting from the thermodynamic instability in stainless steel can be of the order of dT = 40 K, which is exceptionally dangerous for superconducting cables. Suitably calibrated numerical algorithm allows prediction of the behaviour of the material subjected to deformation at low temperatures. The issues presented in the present study are curr...

Zero thermal expansion and ferromagnetism in cubic Sc(1-x)M(x)F3 (M = Ga, Fe) over a wide temperature range.

Science.gov (United States)

Hu, Lei; Chen, Jun; Fan, Longlong; Ren, Yang; Rong, Yangchun; Pan, Zhao; Deng, Jinxia; Yu, Ranbo; Xing, Xianran

2014-10-01

The rare physical property of zero thermal expansion (ZTE) is intriguing because neither expansion nor contraction occurs with temperature fluctuations. Most ZTE, however, occurs below room temperature. It is a great challenge to achieve isotropic ZTE at high temperatures. Here we report the unconventional isotropic ZTE in the cubic (Sc1-xMx)F3 (M = Ga, Fe) over a wide temperature range (linear coefficient of thermal expansion (CTE), αl = 2.34 × 10(-7) K(-1), 300-900 K). Such a broad temperature range with a considerably negligible CTE has rarely been documented. The present ZTE property has been designed using the introduction of local distortions in the macroscopic cubic lattice by heterogeneous cation substitution for the Sc site. Even though the macroscopic crystallographic structure of (Sc0.85Ga0.05Fe0.1)F3 adheres to the cubic system (Pm3̅m) according to the results of X-ray diffraction, the local structure exhibits a slight rhombohedral distortion. This is confirmed by pair distribution function analysis of synchrotron radiation X-ray total scattering. This local distortion may weaken the contribution from the transverse thermal vibration of fluorine atoms to negative thermal expansion, and thus may presumably be responsible for the ZTE. In addition, the present ZTE compounds of (Sc1-xMx)F3 can be functionalized to exhibit high-Tc ferromagnetism and a narrow-gap semiconductor feature. The present study shows the possibility of obtaining ZTE materials with multifunctionality in future work.

Dispersion forces in micromechanics: Casimir and Casimir-Polder forces affected by geometry and non-zero temperature

Energy Technology Data Exchange (ETDEWEB)

Ellingsen, Simen Andreas Aadnoey

2011-01-15

The present thesis focuses on several topics within three separate but related branches of the overall field of dispersion forces. The three branches are: temperature corrections to the Casimir force between real materials (Part 1), explicit calculation of Casimir energy in wedge geometries (Part 2), and Casimir-Polder forces on particles out of thermal equilibrium (Part 3). Part 1 deals primarily with analysis of a previously purported thermodynamic inconsistency in the Casimir-Lifshitz free energy of the interaction of two plane mirrors - violation of the third law of thermodynamics - when the latter's dielectric response is described with dissipative models. It is shown analytically and numerically that the Casimir entropy of the interaction between two metallic mirrors described by the Drude model does tend to zero at zero temperature, provided electronic relaxation does not vanish. The leading order terms at low temperature are found. A similar calculation is carried out for the interaction of semiconductors with small but non-zero DC conductivity. In a generalisation, it is shown that a violation of the third law can only occur for permittivities whose low-frequency behaviour is temperature dependent near zero temperature. A calculation using path integral methods shows that the low temperature behaviour of the interaction of fluctuating Foucault currents in two mirrors of Drude metal is identical to that of the full Casimir-Lifshitz free energy, reasserting a previous finding by Intravaia and Henkel that such fluctuating bulk currents are the physical reason for the anomalous entropy behaviour. In a related effort, an analysis of the frequency dependence of the Casimir force by Ford is generalised to imperfectly reflecting mirrors. A paradox is pointed out, in that the effects of a perturbation of the reflecting properties of the mirrors in a finite frequency window can be calculated in two ways giving different results. It is concluded that optimistic

Ground State of Quasi-One Dimensional Competing Spin Chain Cs2Cu2Mo3O12 at zero and Finite Fields

Science.gov (United States)

Matsui, Kazuki; Goto, Takayuki; Angel, Julia; Watanabe, Isao; Sasaki, Takahiko; Hase, Masashi

The ground state of competing-spin-chain Cs2Cu2Mo3O12 with the ferromagnetic exchange interaction J1 = -93 K on nearest-neighboring spins and the antiferromagnetic one J2 = +33 K on next-nearest-neighboring spins was investigated by ZF/LF-μSR and 133Cs-NMR in the 3He temperature range. The zero-field μSR relaxation rate λ shows a significant increase below 1.85 K, suggesting the existence of magnetic order, which is consistent with the recent report on the specific heat. However, LF decoupling data at the lowest temperature 0.3 K indicate that the spins fluctuate dynamically, suggesting that the system is in a quasi-static ordered state under zero field. This idea is further supported by the fact that the broadening in NMR spectra below TN is weakened at low field below 2 T.

The refrigeration of high temperature superconductors between 25K and 65K

International Nuclear Information System (INIS)

Richardson, R.N.; Scurlock, R.G.; Tavner, A.C.R.

1996-01-01

The present state of the art indicates that acceptable j - H characteristics for power applications of the new high Tc superconductors will only be achieved using materials at temperatures below liquid nitrogen temperature. A boiling point of 27.1K and high specific cooling capacity make neon an eminently suitable choice of refrigerant at these temperatures. A cryostat has been constructed which employs a two stage Gifford-McMahon cooler to liquefy neon gas. The cryostat contains up to 5 litres of liquid neon which can be used for open-quote in-situ close-quote experiments or transfer to another cryostat. Another set of cryostats are being used with liquid nitrogen/oxygen mixtures at reduced pressure for temperatures down to 50K. All these cryostats provide a core facility for characterising and operating high T c superconductors at Southampton

Evaluation of specific heat for superfluid helium between 0 - 2.1 K based on nonlinear theory

International Nuclear Information System (INIS)

Sasaki, Shosuke

2009-01-01

The specific heat of liquid helium was calculated theoretically in the Landau theory. The results deviate from experimental data in the temperature region of 1.3 - 2.1 K. Many theorists subsequently improved the results of the Landau theory by applying temperature dependence of the elementary excitation energy. As well known, many-body system has a total energy of Galilean covariant form. Therefore, the total energy of liquid helium has a nonlinear form for the number distribution function. The function form can be determined using the excitation energy at zero temperature and the latent heat per helium atom at zero temperature. The nonlinear form produces new temperature dependence for the excitation energy from Bose condensate. We evaluate the specific heat using iteration method. The calculation results of the second iteration show good agreement with the experimental data in the temperature region of 0 - 2.1 K, where we have only used the elementary excitation energy at 1.1 K.

Zero-leakage shut-off butterflies for high-temperature applications; Dichtschliessende Absperrklappen fuer die Hochtemperaturtechnik

Energy Technology Data Exchange (ETDEWEB)

Meier, N. [Krombach Armaturen, Kreuztal (Germany)

2000-03-01

Over many years, zero-leakage butterfly valves have eminently proven their capabilities in a large range of elevated-temperature and elevated-pressure processes. This article examines the basic design differences between various butterfly valves. These differences are, among other factors, important indicators of the suitability of the various valve types for their use in industry. (orig.) [German] Dichtschliessende Absperrklappen haben sich ueber Jahre in vielen Prozessen, die unter hoeherem Druck und hoeherer Temperatur ablaufen, bestens bewaehrt. Der Beitrag zeigt die grundsaetzlichen konstruktiven Unterschiede dichtschliessender Absperrklappen. Diese Unterschiede sind unter anderem Indikatoren fuer die Prozesstauglichkeit von Absperrklappen in der Industrie. (orig.)

Pusat Tenaga Malaysia's Zero Energy Office (ZEO) Building

DEFF Research Database (Denmark)

Tang, C.K.; Reimann, Gregers Peter; Kristensen, Poul Erik

Technical Review of the Zero Energy Office building in Malaysia. The building, which has an energy index of 50 kWh/m2/year, reaches a net annual energy of zero through the use of building integrated photovoltaic panels. For reference, ordinary offices in Malaysia consume 200 - 300 kWh/m2/year...

Floating potential in electronegative plasmas for non-zero ion temperatures

Science.gov (United States)

Regodón, Guillermo Fernando; Fernández Palop, José Ignacio; Tejero-del-Caz, Antonio; Díaz-Cabrera, Juan Manuel; Carmona-Cabezas, Rafael; Ballesteros, Jerónimo

2018-02-01

The floating potential of a Langmuir probe immersed in an electronegative plasma is studied theoretically under the assumption of radial positive ion fluid movement for non-zero positive ion temperature: both cylindrical and spherical geometries are studied. The model is solvable exactly. The special characteristics of the electronegative pre-sheath are found and the influence of the stratified electronegative pre-sheath is shown to be very small in practical applications. It is suggested that the use of the floating potential in the measurement of negative ions population density is convenient, in view of the numerical results obtained. The differences between the two radial geometries, which become very important for small probe radii of the order of magnitude of the Debye length, are studied.

Zero-temperature entropy of fully frustrated generalized Sierpiński gaskets

Science.gov (United States)

Chang, C. Y.; Hui, P. M.; Yu, K. W.

1993-01-01

The Ising model with antiferromagnetic couplings on a family of generalized Sierpiński gaskets is studied using an exact technique developed recently by Stinchcombe [Phys. Rev. B 41 (1990) 2510]. A general expression of the zero-temperature entropy per spin, SAFMb(0), is given for general b, where b is a rescaling factor characterizing the fractals. Exact expressions for SAFMb (0) are derived for the cases b = 2,3,4,5,6. These expressions are evaluated numerically and results are compared to those obtained previously by numerical iterations of renormalization-group equations. The asymptotic behavior of SAFMb(0) in the limit of large b is discussed.

PLA and single component silicone rubber blends for sub-zero temperature blown film packaging applications

Science.gov (United States)

Meekum, Utai; Khiansanoi, Apichart

2018-06-01

The poly(lactic acid) (PLA) blend with single component silicone rubber in the presence of reactive amino silane coupling agent and polyester polyols plasticizer were studied. The manufacturing of film packaging for sub-zero temperature applications from the PLA blend was the main objective. The mechanical properties, especially the impact strengths, of PLA/silicone blends were significantly depended on the silicone loading. The outstanding impact strengths, tested at sub-zero temperature, of the blend having silicone content of 8.0 phr was achieved. It was chosen as the best candidate for the processability improvement. Adding the talc filler into the PLA/silicone blend to enhance the rheological properties was investigated. The ductility of the talc filled blends were decreased with increasing the filler contents. However, the shear viscosity of the blend was raised with talc loading. The blend loaded with 40 phr of talc filler was justified as the optimal formula for the blown film process testing and it was successfully performed with a few difficulties. The obtained blown film showed relative good flexibility in comparison with LDPE but it has low transparency.

Approach To Absolute Zero

Indian Academy of Sciences (India)

more and more difficult to remove heat as one approaches absolute zero. This is the ... A new and active branch of engineering ... This temperature is called the critical temperature, Te' For sulfur dioxide the critical ..... adsorbent charcoal.

Robust zero resistance in a superconducting high-entropy alloy at pressures up to 190 GPa

Science.gov (United States)

Guo, Jing; Wang, Honghong; von Rohr, Fabian; Wang, Zhe; Cai, Shu; Zhou, Yazhou; Yang, Ke; Li, Aiguo; Jiang, Sheng; Wu, Qi; Cava, Robert J.; Sun, Liling

2017-12-01

We report the observation of extraordinarily robust zero-resistance superconductivity in the pressurized (TaNb)0.67(HfZrTi)0.33 high-entropy alloy--a material with a body-centered-cubic crystal structure made from five randomly distributed transition-metal elements. The transition to superconductivity (TC) increases from an initial temperature of 7.7 K at ambient pressure to 10 K at ˜60 GPa, and then slowly decreases to 9 K by 190.6 GPa, a pressure that falls within that of the outer core of the earth. We infer that the continuous existence of the zero-resistance superconductivity from 1 atm up to such a high pressure requires a special combination of electronic and mechanical characteristics. This high-entropy alloy superconductor thus may have a bright future for applications under extreme conditions, and also poses a challenge for understanding the underlying quantum physics.

Superconducting Mercury-Based Cuprate Films with a Zero-Resistance Transition Temperature of 124 Kelvin

Science.gov (United States)

Tsuei, C. C.; Gupta, A.; Trafas, G.; Mitzi, D.

1994-03-01

The synthesis of high-quality films of the recently discovered mercury-based cuprate films with high transition temperatures has been plagued by problems such as the air sensitivity of the cuprate precursor and the volatility of Hg and HgO. These processing difficulties have been circumvented by a technique of atomic-scale mixing of the HgO and cuprate precursors, use of a protective cap layer, and annealing in an appropriate Hg and O_2 environment. With this procedure, a zero-resistance transition temperature as high as 124 kelvin in c axis-oriented epitaxial HgBa_2CaCu_2O6+δ films has been achieved.

Superconducting mercury-based cuprate films with a zero-resistance transition temperature of 124 Kelvin.

Science.gov (United States)

Tsuei, C C; Gupta, A; Trafas, G; Mitzi, D

1994-03-04

The synthesis of high-quality films of the recently discovered mercury-based cuprate films with high transition temperatures has been plagued by problems such as the air sensitivity of the cuprate precursor and the volatility of Hg and HgO. These processing difficulties have been circumvented by a technique of atomic-scale mixing of the HgO and cuprate precursors, use of a protective cap layer, and annealing in an appropriate Hg and O(2) environment. With this procedure, a zero-resistance transition temperature as high as 124 kelvin in c axis-oriented epitaxial HgBa(2)CaCu(2)O(6+delta) films has been achieved.

Coarsening in 3D nonconserved Ising model at zero temperature: Anomaly in structure and slow relaxation of order-parameter autocorrelation

Science.gov (United States)

Chakraborty, Saikat; Das, Subir K.

2017-09-01

Via Monte Carlo simulations we study pattern and aging during coarsening in a nonconserved nearest-neighbor Ising model, following quenches from infinite to zero temperature, in space dimension d = 3. The decay of the order-parameter autocorrelation function appears to obey a power-law behavior, as a function of the ratio between the observation and waiting times, in the large ratio limit. However, the exponent of the power law, estimated accurately via a state-of-the-art method, violates a well-known lower bound. This surprising fact has been discussed in connection with a quantitative picture of the structural anomaly that the 3D Ising model exhibits during coarsening at zero temperature. These results are compared with those for quenches to a temperature above that of the roughening transition.

Dynamical equations for time-ordered Green’s functions: from the Keldysh time-loop contour to equilibrium at finite and zero temperature

International Nuclear Information System (INIS)

Ness, H; Dash, L K

2012-01-01

We study the dynamical equation of the time-ordered Green’s function at finite temperature. We show that the time-ordered Green’s function obeys a conventional Dyson equation only at equilibrium and in the limit of zero temperature. In all other cases, i.e. finite temperature at equilibrium or non-equilibrium, the time-ordered Green’s function obeys instead a modified Dyson equation. The derivation of this result is obtained from the general formalism of the non-equilibrium Green’s functions on the Keldysh time-loop contour. At equilibrium, our result is fully consistent with the Matsubara temperature Green’s function formalism and also justifies rigorously the correction terms introduced in an ad hoc way with Hedin and Lundqvist. Our results show that one should use the appropriate dynamical equation for the time-ordered Green’s function when working beyond the equilibrium zero-temperature limit.

Zero-temperature Kosterlitz-Thouless transition in a two-dimensional quantum system

International Nuclear Information System (INIS)

Castelnovo, Claudio; Chamon, Claudio; Mudry, Christopher; Pujol, Pierre

2007-01-01

We construct a local interacting quantum dimer model on the square lattice, whose zero-temperature phase diagram is characterized by a line of critical points separating two ordered phases of the valence bond crystal type. On one side, the line of critical points terminates in a quantum transition inherited from a Kosterlitz-Thouless transition in an associated classical model. We also discuss the effect of a longer-range dimer interaction that can be used to suppress the line of critical points by gradually shrinking it to a single point. Finally, we propose a way to generalize the quantum Hamiltonian to a dilute dimer model in presence of monomers and we qualitatively discuss the phase diagram

Towards a comprehensive theory for He II: I. A zero-temperature hybrid approach

International Nuclear Information System (INIS)

Ghassib, H.B.; Khudeir, A.M.

1982-09-01

A simple hybrid approach based on a gauge theory as well as a Hartree formalism, is presented for He II at zero temperature. Although this is intended to be merely a first step in an all-embracing theory, it already resolves quite neatly several old inconsistencies and corrects a few errors. As an illustration of its feasibility, a crude but instructive calculation is performed for the static structure factor of the system at low momentum transfers. A number of planned extensions and generalizations are outlined. (author)

Application of hierarchical equations of motion (HEOM) to time dependent quantum transport at zero and finite temperatures

Science.gov (United States)

Tian, Heng; Chen, GuanHua

2013-10-01

Going beyond the limitations of our earlier works [X. Zheng, F. Wang, C.Y. Yam, Y. Mo, G.H. Chen, Phys. Rev. B 75, 195127 (2007); X. Zheng, G.H. Chen, Y. Mo, S.K. Koo, H. Tian, C.Y. Yam, Y.J. Yan, J. Chem. Phys. 133, 114101 (2010)], we propose, in this manuscript, a new alternative approach to simulate time-dependent quantum transport phenomenon from first-principles. This new practical approach, still retaining the formal exactness of HEOM framework, does not rely on any intractable parametrization scheme and the pole structure of Fermi distribution function, thus, can seamlessly incorporated into first-principles simulation and treat transient response of an open electronic systems to an external bias voltage at both zero and finite temperatures on the equal footing. The salient feature of this approach is surveyed, and its time complexity is analysed. As a proof-of-principle of this approach, simulation of the transient current of one dimensional tight-binding chain, driven by some direct external voltages, is demonstrated.

Interlacing of zeros of quasi-orthogonal meixner polynomials | Driver ...

African Journals Online (AJOL)

... interlacing of zeros of quasi-orthogonal Meixner polynomials Mn(x;β; c) with the zeros of their nearest orthogonal counterparts Mt(x;β + k; c), l; n ∈ ℕ, k ∈ {1; 2}; is also discussed. Mathematics Subject Classication (2010): 33C45, 42C05. Key words: Discrete orthogonal polynomials, quasi-orthogonal polynomials, Meixner

The zero-action hypothesis and high-temperature thermodynamics in the heterotic superstring theory

Science.gov (United States)

Pollock, M. D.

2005-07-01

The effective action S for the Einstein theory of gravity coupled to massless scalar fields phi, spinor fields ψ and gauge vector fields Fij describing radiation, so that FijFij = 0, vanishes identically after substitution from the classical equations of motion, thus allowing a perfect fluid for which the energy density ρ and pressure p = (γ - 1)ρ are related by values of the adiabatic index throughout the range 4/3 high-temperature limit T Gt TH, after Euclideanizing the time coordinate, where TH is the Hagedorn temperature. The response of the action to the operators T, C and P is also discussed, T-invariance requiring γ = 2 and hence S = 0, and P-invariance requiring S = 0, showing that the zero-action hypothesis can be understood in terms of these discrete symmetries.

Conceptual design of a forced-flow-cooled 20-kA current lead using Ag-alloy-sheathed Bi-2223 high-temperature superconductors

International Nuclear Information System (INIS)

Heller, R.

1994-11-01

The use of high-temperature superconductors in current leads to reduce refrigeration power has been investigated by many groups in the past. Most used YBCO and Bi-2212 bulk superconductors, although their critical current density is not very high. In this paper, BI-2223 HTSC tapes sheathed with Ag alloys are used in the design of a 20-kA current lead because of their higher critical current in medium magnetic fields. The lead current of 20 kA is related to the coil current of the planned stellarator WENDELSTEIN 7-X. Forced-now helium cooling has been used in the design, allowing position-independent and well-controlled operation. The design characteristics of the lead are presented and 4-K helium cooling of the whole lead, as well as 60-K helium cooling of the copper part of the lead, is discussed. The power consumption at zero current, and the lead's behaviour in case of loss of coolant flow, are given, The results of the design allow extrapolation to current leads of the 50-kA range

Current-voltage temperature characteristics of Au/n-Ge (1 0 0) Schottky diodes

Energy Technology Data Exchange (ETDEWEB)

Chawanda, Albert, E-mail: albert.chawanda@up.ac.za [Midlands State University, Bag 9055 Gweru (Zimbabwe); University of Pretoria, 0002 Pretoria (South Africa); Mtangi, Wilbert; Auret, Francois D; Nel, Jacqueline [University of Pretoria, 0002 Pretoria (South Africa); Nyamhere, Cloud [Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Diale, Mmantsae [University of Pretoria, 0002 Pretoria (South Africa)

2012-05-15

The variation in electrical characteristics of Au/n-Ge (1 0 0) Schottky contacts have been systematically investigated as a function of temperature using current-voltage (I-V) measurements in the temperature range 140-300 K. The I-V characteristics of the diodes indicate very strong temperature dependence. While the ideality factor n decreases, the zero-bias Schottky barrier height (SBH) ({Phi}{sub B}) increases with the increasing temperature. The I-V characteristics are analyzed using the thermionic emission (TE) model and the assumption of a Gaussian distribution of the barrier heights due to barrier inhomogeneities at the metal-semiconductor interface. The zero-bias barrier height {Phi}{sub B} vs. 1/2 kT plot has been used to show the evidence of a Gaussian distribution of barrier heights and values of {Phi}{sub B}=0.615 eV and standard deviation {sigma}{sub s0}=0.0858 eV for the mean barrier height and zero-bias standard deviation have been obtained from this plot, respectively. The Richardson constant and the mean barrier height from the modified Richardson plot were obtained as 1.37 A cm{sup -2} K{sup -2} and 0.639 eV, respectively. This Richardson constant is much smaller than the reported of 50 A cm{sup -2} K{sup -2}. This may be due to greater inhomogeneities at the interface.

The Paris Agreement zero-emissions goal is not always consistent with the 1.5 °C and 2 °C temperature targets

Science.gov (United States)

Tanaka, Katsumasa; O'Neill, Brian C.

2018-04-01

The Paris Agreement stipulates that global warming be stabilized at well below 2 °C above pre-industrial levels, with aims to further constrain this warming to 1.5 °C. However, it also calls for reducing net anthropogenic greenhouse gas (GHG) emissions to zero during the second half of this century. Here, we use a reduced-form integrated assessment model to examine the consistency between temperature- and emission-based targets. We find that net zero GHG emissions are not necessarily required to remain below 1.5 °C or 2 °C, assuming either target can be achieved without overshoot. With overshoot, however, the emissions goal is consistent with the temperature targets, and substantial negative emissions are associated with reducing warming after it peaks. Temperature targets are put at risk by late achievement of emissions goals and the use of some GHG emission metrics. Refinement of Paris Agreement emissions goals should include a focus on net zero CO2—not GHG—emissions, achieved early in the second half of the century.

Comparison of zero-sequence injection methods in cascaded H-bridge multilevel converters for large-scale photovoltaic integration

DEFF Research Database (Denmark)

Yu, Yifan; Konstantinou, Georgios; Townsend, Christopher David

2017-01-01

to maintain three-phase balanced grid currents with unbalanced power generation. This study theoretically compares power balance capabilities of various zero-sequence injection methods based on two metrics which can be easily generalised for all CHB applications to PV systems. Experimental results based......Photovoltaic (PV) power generation levels in the three phases of a multilevel cascaded H-bridge (CHB) converter can be significantly unbalanced, owing to different irradiance levels and ambient temperatures over a large-scale solar PV power plant. Injection of a zero-sequence voltage is required...... on a 430 V, 10 kW, three-phase, seven-level cascaded H-bridge converter prototype confirm superior performance of the optimal zero-sequence injection technique....

Chiral density wave versus pion condensation at finite density and zero temperature

Science.gov (United States)

Andersen, Jens O.; Kneschke, Patrick

2018-04-01

The quark-meson model is often used as a low-energy effective model for QCD to study the chiral transition at finite temperature T , baryon chemical potential μB , and isospin chemical potential μI . We determine the parameters of the model by matching the meson and quark masses, as well as the pion decay constant to their physical values using the on shell (OS) and modified minimal subtraction (MS ¯ ) schemes. In this paper, the existence of different phases at zero temperature is studied. In particular, we investigate the competition between an inhomogeneous chiral condensate and a homogeneous pion condensate. For the inhomogeneity, we use a chiral-density wave ansatz. For a sigma mass of 600 MeV, we find that an inhomogeneous chiral condensate exists only for pion masses below approximately 37 MeV. We also show that due to our parameter fixing, the onset of pion condensation takes place exactly at μIc=1/2 mπ in accordance with exact results.

Zero-valent iron nanoparticles preparation

International Nuclear Information System (INIS)

Oropeza, S.; Corea, M.; Gómez-Yáñez, C.; Cruz-Rivera, J.J.; Navarro-Clemente, M.E.

2012-01-01

Graphical abstract: Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH 3 ) 3 ) 2 ] 2 ] at room temperature and a pressure of 3 atm. The synthesized nanoparticles were spherical and had diameters less than 5 nm. Highlights: ► Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH 3 ) 3 ) 2 ] 2 ]. ► The conditions of reaction were at room temperature and a pressure of 3 atm. ► The synthesized nanoparticles were spherical and had diameters less than 5 nm. -- Abstract: Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH 3 ) 3 ) 2 ] 2 ] at room temperature and a pressure of 3 atm. To monitor the reaction, a stainless steel pressure reactor lined with PTFE and mechanically stirred was designed. This design allowed the extraction of samples at different times, minimizing the perturbation in the system. In this way, the shape and the diameter of the nanoparticles produced during the reaction were also monitored. The results showed the production of zero-valent iron nanoparticles that were approximately 5 nm in diameter arranged in agglomerates. The agglomerates grew to 900 nm when the reaction time increased up to 12 h; however, the diameter of the individual nanoparticles remained almost the same. During the reaction, some byproducts constituted by amino species acted as surfactants; therefore, no other surfactants were necessary.

Amplitude analysis of the K-K+ system produced in the reactions π-p → K-K+N and π+N → K-K+p at 6 GeV/c

International Nuclear Information System (INIS)

Cohen, D.; Ayres, D.S.; Diebold, R.; Kramer, S.L.; Pawlicki, A.J.; Wicklund, A.B.

1978-06-01

An amplitude analysis of the K - K + system produced in the reactions π - p → K - K + n and π + n → K - K + p was carried out using data from a high statistics experiment carried out with the Argonne Effective Mass Spectrometer. Combining the results from the two reactions allows the separation of the KantiK production amplitudes into their isospin-zero and one components. An enhancement is deserved in the S-wave amplitude near 1300 MeV which we call the S'. Using various physical arguments, including the t dependence of the amplitudes, six out of eight mathematically-allowed solutions can be eliminated for the magnitudes and phases of the amplitudes and shown that this new S-wave state has isospin zero. Requiring a reasonable behavior for the isospin-one P wave shows that the S' amplitude has a slow phase variation through the peak region

Semiconductor resistance thermometer for the temperature range 300-0.3 K

International Nuclear Information System (INIS)

Zinov'eva, K.N.; Zarubin, L.I.; Nemish, I.Yu.; Vorobkalo, F.M.; Boldarev, S.T.; AN Ukrainskoj SSR, Kiev. Inst. Poluprovodnikov)

1979-01-01

Thermometric characteristics of semiconductor resistor thermometers for the temperature range from 300 to 0.3 K and from 77 to 0.3 K are given. Temperature dependence of thermometer resistances in the 300-1.3 K range was measured in cryostats with pumping-out of N 2 , H 2 and 4 He. For measurements below 1.3 K use was made of a 3 H- 4 He dissolving cryostat. The accuracy of measuring temperatures in the 1.3-0.3 K range is not below +-0.003 K, the error in determining thermometer resistances does not exceed 1%. The analysis of obtained thermometric characteristics of several series of semiconductor resistance thermometers showed that observed insignificant spread of resistances of thermometers in one series and identity of characteristics allows them to be used without preliminary calibration for relatively coarse measurements in the range from 3O0 to 0.3 K. Besides, it has been found that in the 4.2-0.3 K range the thermometric characteristics represent a straight line in the lgR-Tsup(-n) coordinates, where R is the thermometer resistance, T is the temperature and n=0.5. Thus, the thermometers of the same series can be calibrated only in 2 or 3 reference point measurements

Discrete breathers in graphane: Effect of temperature

Energy Technology Data Exchange (ETDEWEB)

Baimova, J. A., E-mail: julia.a.baimova@gmail.com [Russian Academy of Sciences, Institute of Metal Physics, Ural Branch (Russian Federation); Murzaev, R. T.; Lobzenko, I. P.; Dmitriev, S. V. [Russian Academy of Sciences, Institute for Metals Superplasticity Problems (Russian Federation); Zhou, Kun [Nanyang Technological University, School of Mechanical and Aerospace Engineering (Singapore)

2016-05-15

The discrete breathers in graphane in thermodynamic equilibrium in the temperature range 50–600 K are studied by molecular dynamics simulation. A discrete breather is a hydrogen atom vibrating along the normal to a sheet of graphane at a high amplitude. As was found earlier, the lifetime of a discrete breather at zero temperature corresponds to several tens of thousands of vibrations. The effect of temperature on the decay time of discrete breathers and the probability of their detachment from a sheet of graphane are studied in this work. It is shown that closely spaced breathers can exchange energy with each other at zero temperature. The data obtained suggest that thermally activated discrete breathers can be involved in the dehydrogenation of graphane, which is important for hydrogen energetics.

Transmission of Helium Isotopes through Graphdiyne Pores: Tunneling versus Zero Point Energy Effects.

Science.gov (United States)

Hernández, Marta I; Bartolomei, Massimiliano; Campos-Martínez, José

2015-10-29

Recent progress in the production of new two-dimensional (2D) nanoporous materials is attracting considerable interest for applications to isotope separation in gases. In this paper we report a computational study of the transmission of (4)He and (3)He through the (subnanometer) pores of graphdiyne, a recently synthesized 2D carbon material. The He-graphdiyne interaction is represented by a force field parametrized upon ab initio calculations, and the (4)He/(3)He selectivity is analyzed by tunneling-corrected transition state theory. We have found that both zero point energy (of the in-pore degrees of freedom) and tunneling effects play an extraordinary role at low temperatures (≈20-30 K). However, both quantum features work in opposite directions in such a way that the selectivity ratio does not reach an acceptable value. Nevertheless, the efficiency of zero point energy is in general larger, so that (4)He tends to diffuse faster than (3)He through the graphdiyne membrane, with a maximum performance at 23 K. Moreover, it is found that the transmission rates are too small in the studied temperature range, precluding practical applications. It is concluded that the role of the in-pore degrees of freedom should be included in computations of the transmission probabilities of molecules through nanoporous materials.

A zero-power warming chamber for investigating plant responses to rising temperature

Directory of Open Access Journals (Sweden)

K. F. Lewin

2017-09-01

Full Text Available Advances in understanding and model representation of plant and ecosystem responses to rising temperature have typically required temperature manipulation of research plots, particularly when considering warming scenarios that exceed current climate envelopes. In remote or logistically challenging locations, passive warming using solar radiation is often the only viable approach for temperature manipulation. However, current passive warming approaches are only able to elevate the mean daily air temperature by  ∼  1.5 °C. Motivated by our need to understand temperature acclimation in the Arctic, where warming has been markedly greater than the global average and where future warming is projected to be  ∼  2–3 °C by the middle of the century; we have developed an alternative approach to passive warming. Our zero-power warming (ZPW chamber requires no electrical power for fully autonomous operation. It uses a novel system of internal and external heat exchangers that allow differential actuation of pistons in coupled cylinders to control chamber venting. This enables the ZPW chamber venting to respond to the difference between the external and internal air temperatures, thereby increasing the potential for warming and eliminating the risk of overheating. During the thaw season on the coastal tundra of northern Alaska our ZPW chamber was able to elevate the mean daily air temperature 2.6 °C above ambient, double the warming achieved by an adjacent passively warmed control chamber that lacked our hydraulic system. We describe the construction, evaluation and performance of our ZPW chamber and discuss the impact of potential artefacts associated with the design and its operation on the Arctic tundra. The approach we describe is highly flexible and tunable, enabling customization for use in many different environments where significantly greater temperature manipulation than that possible with existing passive warming

A zero-power warming chamber for investigating plant responses to rising temperature

Science.gov (United States)

Lewin, Keith F.; McMahon, Andrew M.; Ely, Kim S.; Serbin, Shawn P.; Rogers, Alistair

2017-09-01

Advances in understanding and model representation of plant and ecosystem responses to rising temperature have typically required temperature manipulation of research plots, particularly when considering warming scenarios that exceed current climate envelopes. In remote or logistically challenging locations, passive warming using solar radiation is often the only viable approach for temperature manipulation. However, current passive warming approaches are only able to elevate the mean daily air temperature by ˜ 1.5 °C. Motivated by our need to understand temperature acclimation in the Arctic, where warming has been markedly greater than the global average and where future warming is projected to be ˜ 2-3 °C by the middle of the century; we have developed an alternative approach to passive warming. Our zero-power warming (ZPW) chamber requires no electrical power for fully autonomous operation. It uses a novel system of internal and external heat exchangers that allow differential actuation of pistons in coupled cylinders to control chamber venting. This enables the ZPW chamber venting to respond to the difference between the external and internal air temperatures, thereby increasing the potential for warming and eliminating the risk of overheating. During the thaw season on the coastal tundra of northern Alaska our ZPW chamber was able to elevate the mean daily air temperature 2.6 °C above ambient, double the warming achieved by an adjacent passively warmed control chamber that lacked our hydraulic system. We describe the construction, evaluation and performance of our ZPW chamber and discuss the impact of potential artefacts associated with the design and its operation on the Arctic tundra. The approach we describe is highly flexible and tunable, enabling customization for use in many different environments where significantly greater temperature manipulation than that possible with existing passive warming approaches is desired.

Classification of non-simple C*-algebras of real rank zero

DEFF Research Database (Denmark)

Arklint, Sara Esther

for real rank zero graph algebras over primitive ideal spaces that admit classification. As a consequence of completeness of filtered K-theory combined with this range result, one can conclude that real rank zero extensions of stabilized Cuntz-Krieger algebras are stabilized Cuntz-Krieger algebras......This thesis deals with classification of nonsimple C-algebras of real rank zero, and whether filtered K-theory is a suitable invariant for this purpose. As a consequence of the result of E. Kirchberg for purely infinite, nuclear C-algebras with a finite primitive ideal space, it suffices to lift...... the thesis is the following: is it possible to achieve the desired classification result for arbitrary finite primitive ideal spaces by restricting to C-algebras of real rank zero that possibly satisfy further restrictions on K-theory? The thesis consists of an account of the relevant theory and the relevant...

Characterization of the magnetic properties of NdFeB thick films exposed to elevated temperatures

Science.gov (United States)

Fujiwara, Ryogen; Devillers, Thibaut; Givord, Dominique; Dempsey, Nora M.

2018-05-01

Hard magnetic films used in magnetic micro-systems may be exposed to elevated temperatures during film and system fabrication and also during use of the micro-system. In this work, we studied the influence of temperature on the magnetic properties of 10 μm thick out-of-plane textured NdFeB films fabricated by high rate triode sputtering. Out-of-plane hysteresis loops were measured in the range 300K - 650K to establish the temperature dependence of coercivity, magnetization at 7 T and remanent magnetization. Thermal demagnetization was measured and magnetization losses were recorded from 350K in films heated under zero or low (-0.1 T) external field and from 325 K for films heated under an external field of -0.5 T. The effect of thermal cycling under zero field on the remanent magnetization was also studied and it was found that cycling between room temperature and 323 K did not lead to any significant loss in remanence at room temperature, while a 4% drop is recorded when the sample is cycled between RT and 343K. Measurement of hysteresis loops at room temperature following exposure to elevated temperatures reveals that while remanent magnetisation is practically recovered in all cases, irreversible losses in coercivity occur (6.7 % following heating to 650K, and 1.3 % following heating to 343K). The relevance of these results is discussed in terms of system fabrication and use.

Zero-valent iron nanoparticles preparation

Energy Technology Data Exchange (ETDEWEB)

Oropeza, S. [Instituto Politécnico Nacional, ESIQIE, UPALM, Edificio Z-6, Primer Piso, C.P. 07738, Col. San Pedro Zacatenco, México D.F. (Mexico); Corea, M., E-mail: mcoreat@yahoo.com.mx [Instituto Politécnico Nacional, ESIQIE, UPALM, Edificio Z-6, Primer Piso, C.P. 07738, Col. San Pedro Zacatenco, México D.F. (Mexico); Gómez-Yáñez, C. [Instituto Politécnico Nacional, ESIQIE, UPALM, Edificio Z-6, Primer Piso, C.P. 07738, Col. San Pedro Zacatenco, México D.F. (Mexico); Cruz-Rivera, J.J. [Universidad Autónoma de San Luis Potosí, Instituto de Metalurgia, Sierra Leona 550, San Luis Potosí, C.P. 78210 (Mexico); Navarro-Clemente, M.E., E-mail: mnavarroc@ipn.mx [Instituto Politécnico Nacional, ESIQIE, UPALM, Edificio Z-6, Primer Piso, C.P. 07738, Col. San Pedro Zacatenco, México D.F. (Mexico)

2012-06-15

Graphical abstract: Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH{sub 3}){sub 3}){sub 2}]{sub 2}] at room temperature and a pressure of 3 atm. The synthesized nanoparticles were spherical and had diameters less than 5 nm. Highlights: ► Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH{sub 3}){sub 3}){sub 2}]{sub 2}]. ► The conditions of reaction were at room temperature and a pressure of 3 atm. ► The synthesized nanoparticles were spherical and had diameters less than 5 nm. -- Abstract: Zero-valent iron nanoparticles were synthesized by hydrogenating [Fe[N(Si(CH{sub 3}){sub 3}){sub 2}]{sub 2}] at room temperature and a pressure of 3 atm. To monitor the reaction, a stainless steel pressure reactor lined with PTFE and mechanically stirred was designed. This design allowed the extraction of samples at different times, minimizing the perturbation in the system. In this way, the shape and the diameter of the nanoparticles produced during the reaction were also monitored. The results showed the production of zero-valent iron nanoparticles that were approximately 5 nm in diameter arranged in agglomerates. The agglomerates grew to 900 nm when the reaction time increased up to 12 h; however, the diameter of the individual nanoparticles remained almost the same. During the reaction, some byproducts constituted by amino species acted as surfactants; therefore, no other surfactants were necessary.

Zero-Bias Offsets in the Low-Temperature Dark Current of Quantum-Well Infrared Photodetectors

National Research Council Canada - National Science Library

Singh, Anjali

1999-01-01

.... In this environment, the detector arrays may need to be operated at temperatures lower then 77 K. At these temperatures, tunneling mechanisms such as Fowler-Nordheim and trap-assisted tunneling could dominate the dark current...

Development of an experimental variable temperature set-up for a temperature range from 2.2 K to 325 K for cost-effective temperature sensor calibration

Science.gov (United States)

Pal, Sandip; Kar, Ranjan; Mandal, Anupam; Das, Ananda; Saha, Subrata

2017-05-01

A prototype of a variable temperature insert has been developed in-house as a cryogenic thermometer calibration facility. It was commissioned in fulfilment of the very stringent requirements of the temperature control of the cryogenic system. The calibration facility is designed for calibrating industrial cryogenic thermometers that include a temperature sensor and the wires heat-intercept in the 2.2 K-325 K temperature range. The isothermal section of the calibration block onto which the thermometers are mounted is weakly linked with the temperature control zone mounted with cooling capillary coil and cryogenic heater. The connecting wires of the thermometer are thermally anchored with the support of the temperature insert. The calibration procedure begins once the temperature of the support is stabilized. Homogeneity of the calibration block’s temperature is established both by simulation and by cross-comparison of two calibrated sensors. The absolute uncertainty present in temperature measurement is calculated and found comparable with the measured uncertainty at different temperature points. Measured data is presented in comparison to the standard thermometers at fixed points and it is possible to infer that the absolute accuracy achieved is better than  ±0.5% of the reading in comparison to the fixed point temperature. The design and development of simpler, low cost equipment, and approach to analysis of the calibration results are discussed further in this paper, so that it can be easily devised by other researchers.

Further properties of the zeros of Bessel functions

Directory of Open Access Journals (Sweden)

Carla Giordano

1987-11-01

Full Text Available New monotonicity and convexity properties for the zeros cνk  (k=1,2,... of the Bessel functions are proved. New inequalities for cνk are also given. These inequalities are useful for small values of ν.

Sum-rate analysis of spectrum sharing spatial multiplexing MIMO systems with zero-forcing and multiuser diversity

KAUST Repository

Yang, Liang

2013-06-01

This paper considers a multiuser spectrum sharing (SS) multiple-input multiple-output (MIMO) system with zero-forcing (ZF) operating in a Rayleigh fading environment. We provide an asymptotic sum-rate analysis to investigate the effects of different parameters on the multiuser diversity gain. For a ZF SS spatial multiplexing system with scheduling, the asymptotic sum-rate scales like Nt log2(Q(Nt Np√K - 1)/N t), where Np denotes the number of antennas of primary receiver, Q is the interference temperature, and K represents the number of secondary transmitters. © 2013 IEEE.

Magnetic Levitation Force Measurement System at Any Low Temperatures From 20 K To 300 K

Science.gov (United States)

Celik, Sukru; Guner, S. Baris; Coskun, Elvan

2015-03-01

Most of the magnetic levitation force measurements in previous studies were performed at liquid nitrogen temperatures. For the levitation force of MgB2 and iron based superconducting samples, magnetic levitation force measurement system is needed. In this study, magnetic levitation force measurement system was designed. In this system, beside vertical force versus vertical motion, lateral and vertical force versus lateral motion measurements, the vertical force versus temperature at the fixed distance between permanent magnet PM - superconducting sample SS and the vertical force versus time measurements were performed at any temperatures from 20 K to 300 K. Thanks to these measurements, the temperature dependence, time dependence, and the distance (magnetic field) and temperature dependences of SS can be investigated. On the other hand, the magnetic stiffness MS measurements can be performed in this system. Using the measurement of MS at different temperature in the range, MS dependence on temperature can be investigated. These measurements at any temperatures in the range help to the superconductivity properties to be characterized. This work was supported by TUBTAK-the Scientific and technological research council of Turkey under project of MFAG - 110T622. This system was applied to the Turkish patent institute with the Application Number of 2013/13638 on 22/11/2013.

Radiation measurements by pn junction InSb detector at the temperature from 4.2 K to 115 K

International Nuclear Information System (INIS)

Kanno, Ikuo; Yoshihara, Fumiki; Nouchi, Ryo; Sugiura, Osamu; Murase, Yasuhiro; Nakamura, Tatsuya; Katagiri, Masaki

2003-01-01

We fabricated the pn junction-type detectors on a p-type InSb substrate. Both sides of the InSb substrate were etched using a mixture of nitric and lactic acids. On the top side surface, Sn and Al were deposited by heat evaporation and then the Sn was diffused into the p-type InSb by lamp annealing and resulted in the n-type layer. Based on the confirmation of the performance of the InSb detector at temperatures of 0.5 K and 4.2 K, we concentrated on the measurement of alpha particles by the pm junction-type InSb detectors at higher operating temperatures of up to 115 K. The InSb detector showed a wide temperature operating range. We can conclude that all of the voltage was induced slowly by the holes at 4.2 K and mainly as a result of electrons at 77 K. (T. Tanaka)

Experimental study of the density and derived volumetric (excess, apparent, and partial molar volumes) properties of aqueous 1-propanol mixtures at temperatures from 298 K to 582 K and pressures up to 40 MPa

International Nuclear Information System (INIS)

Abdulagatov, I.M.; Azizov, N.D.

2014-01-01

Highlights: • Density of (water + 1-propanol) mixtures. • Excess molar volumes of (water + 1-propanol) mixtures. • Apparent molar volumes of (water + 1-propanol) mixtures. -- Abstract: Densities of (water + 1-propanol) mixtures have been measured over the temperature range from 298 K to 582 K and at pressures up to 40 MPa using the constant-volume piezometer immersed in a precision liquid thermostat. The measurements were made for six compositions of (0.869, 2.465, 2.531, 7.407, 14.377, and 56.348) mol · kg −1 of 1-propanol. The expanded uncertainty of the density, pressure, temperature, and concentration measurements at the 95% confidence level with a coverage factor of k = 2 is estimated to be 0.06%, 0.05%, 15 mK, and 0.015%, respectively. The derived volumetric properties such as excess (V m E ), apparent (V Φ ), and partial (V ¯ 2 ∞ ) molar volumes were calculated using the measured values of density for the mixture and for pure components (water and 1-propanol). The concentration dependences of the apparent molar volumes were extrapolated to zero concentration to yield the partial molar volumes of 1-propanol at infinite dilution (V ¯ 2 ∞ ). The temperature, pressure, and concentration dependence of density and derived properties of the mixture were studied. All experimental and derived properties (excess, apparent, and partial molar volumes) were compared with the reported data by other authors. The small and negative values of excess molar volume for the mixtures were found at all experimental temperatures, pressures, and over the entire concentration range. The excess molar volume minimum is found at concentration about 0.4 mole fraction of 1-propanol. The concentration minimum of the derived apparent molar volumes V Φ near the 2.5 mol · kg −1 (dilute mixture) was observed

Tolerance of Coffea arabica L. seeds to sub zero temperatures

Directory of Open Access Journals (Sweden)

Stefania Vilas Boas Coelho

Full Text Available ABSTRACT Preservation of the quality of coffee seeds is hindered by their intermediate behavior in storage. However, long-term storage at sub zero temperatures may be achieved by adjusting the water content of the seeds. The aim of this study was to evaluate the tolerance of coffee seeds to freezing, in relation to physiological and enzymatic modifications. Coffee seeds were dried in two manners, rapid and slow, to water contents of interest, 0.67, 0.43, 0.25, 0.18, 0.11, and 0.05 g H2O g-¹ dw (dry basis. After drying, the seeds were stored at a temperature of -20 ºC and of 86 ºC for 24 hours and for 12 months, and then compared to seeds in cold storage at 10 ºC. The seeds were evaluated through calculation of percentage of normal seedlings, percentage of seedlings with expanded cotyledonary leaves, dry matter of roots and of hypocotyls, and viability of embryos in the tetrazolium test. Expression of the enzymes superoxide dismutase, catalase, and peroxidase were evaluated by means of electrophoretic analysis. Only seeds dried more slowly to 0.18 g H2O g-1 dw present relative tolerance to storing at -20 °C for 12 months. Coffee seeds do not tolerate storage at a temperature of -86 ºC for 12 months. Water contents below 0.11g H2O g-¹ dw and above 0.43 g H2O g-¹ dw hurt the physiological quality of coffee seeds, regardless of the type of drying, temperature, and storage period. Coffee seed embryos are more tolerant to desiccation and to freezing compared to whole seeds, especially when the seeds are dried to 0.05 g H2O g-¹ dw. The catalase enzyme can be used as a biochemical marker to study tolerance to freezing in coffee seeds.

Spin trapping of radicals formed in gamma-irradiated methanol: effect of the irradiation temperature from 77K to 300K

International Nuclear Information System (INIS)

Schlick, S.; Kevan, L.

1976-01-01

The neutral radicals formed in gamma-irradiated methanol were studied by spin trapping with phenyl-t-butylnitrone (PBN) in an attempt to probe the primary neutral radicals formed. In the temperature range from approximately 157 K to 300 K both CH 2 OH and CH 3 O spin adducts are observed and their limiting ratio at high PBN concentrations is CH 2 OH/CH 3 O=1.5 over this temperature range. Below approximately 157 K this ratio increases exponentially with decreasing temperature with an apparent activation energy of 5.8 kJ/mole (1.4 kcal/mole); this is consistent with the finding that only CH 2 OH radicals are formed by gamma radiolysis at 77 K. Several possible models for the primary neutral radicals formed in gamma-irradiated methanol and their subsequent reactions as a function of irradiation temperature are discussed. It is suggested that the primary radical formation mechanisms are similar in the gas and liquid phases and become temperature dependent when molecular motion is arrested in the solid. (Auth.)

Zero boil-off methods for large-scale liquid hydrogen tanks using integrated refrigeration and storage

Science.gov (United States)

Notardonato, W. U.; Swanger, A. M.; E Fesmire, J.; Jumper, K. M.; Johnson, W. L.; Tomsik, T. M.

2017-12-01

NASA has completed a series of tests at the Kennedy Space Center to demonstrate the capability of using integrated refrigeration and storage (IRAS) to remove energy from a liquid hydrogen (LH2) tank and control the state of the propellant. A primary test objective was the keeping and storing of the liquid in a zero boil-off state, so that the total heat leak entering the tank is removed by a cryogenic refrigerator with an internal heat exchanger. The LH2 is therefore stored and kept with zero losses for an indefinite period of time. The LH2 tank is a horizontal cylindrical geometry with a vacuum-jacketed, multilayer insulation system and a capacity of 125,000 liters. The closed-loop helium refrigeration system was a Linde LR1620 capable of 390W cooling at 20K (without any liquid nitrogen pre-cooling). Three different control methods were used to obtain zero boil-off: temperature control of the helium refrigerant, refrigerator control using the tank pressure sensor, and duty cycling (on/off) of the refrigerator as needed. Summarized are the IRAS design approach, zero boil-off control methods, and results of the series of zero boil-off tests.

An automated thermal relaxation calorimeter for operation at low temperature (0.5KK)

International Nuclear Information System (INIS)

Banerjee, S.; Prins, M.W.J.; Rajeev, K.P.; Raychaudhuri, A.K.

1992-01-01

An automated calorimeter for measurement of specific heat in the temperature range 10K>T>0.5K. It uses sample of moderate size (100-1000 mg), has a moderate precision and accuracy (2%-5%) is easy to operate and the measurements can be done quickly with 3 He economy is described. The accuracy of this calorimeter was checked by measurement of specific heat of copper and that of aluminium near its superconducting transition temperature. (author). 12 refs., 11 figs

Electrical conductivity of molten SnCl2 at temperature as high as 1314 K

International Nuclear Information System (INIS)

Salyulev, Alexander B.; Potapov, Alexei M.

2015-01-01

The electrical conductivity of molten SnCl 2 was measured in a wide temperature range (ΔT=763 K), from 551 K to temperature as high as 1314 K, that is, 391 above the boiling point of the salt. The specific electrical conductance was found to reach its maximum at 1143 K, after that it decreases with the temperature rising.

The anomalous low temperature resistivity of thermally evaporated α-Mn thin film

International Nuclear Information System (INIS)

Ampong, F.K.; Boakye, F.; Nkum, R.K.

2010-01-01

Electrical resistivity measurements have been carried out on thermally evaporated α-Mn thin film between 300 and 1.4 K using the van der Pauw four probe technique. The film was grown on a glass substrate held at a temperature of 373 K, in an ambient pressure of 5x10 -6 Torr. The results show a resistance minimum, a notable characteristic of α-Mn but at a (rather high) temperature of 194±1 K. Below the resistivity maximum which corresponds to 70 K, the resistivity drops by only 0.02 μΩm indicating a rather short range magnetic ordering. The low temperature results show a tendency towards saturation of the resistivity as the temperature approaches zero suggesting a Kondo scattering.

The anomalous low temperature resistivity of thermally evaporated alpha-Mn thin film

Energy Technology Data Exchange (ETDEWEB)

Ampong, F.K., E-mail: kampxx@yahoo.co [Department of Physics, Kwame Nkrumah University of Science and Technology, Kumasi (Ghana); Boakye, F.; Nkum, R.K. [Department of Physics, Kwame Nkrumah University of Science and Technology, Kumasi (Ghana)

2010-08-15

Electrical resistivity measurements have been carried out on thermally evaporated alpha-Mn thin film between 300 and 1.4 K using the van der Pauw four probe technique. The film was grown on a glass substrate held at a temperature of 373 K, in an ambient pressure of 5x10{sup -6} Torr. The results show a resistance minimum, a notable characteristic of alpha-Mn but at a (rather high) temperature of 194+-1 K. Below the resistivity maximum which corresponds to 70 K, the resistivity drops by only 0.02 muOMEGAm indicating a rather short range magnetic ordering. The low temperature results show a tendency towards saturation of the resistivity as the temperature approaches zero suggesting a Kondo scattering.

Low-temperature specific heat of the quasi-two-dimensional charge-density wave compound KMo6O17

Science.gov (United States)

Wang, Junfeng; Xiong, Rui; Yin, Di; Li, Changzhen; Tang, Zheng; Wang, Ququan; Shi, Jing; Wang, Yue; Wen, Haihu

2006-05-01

Low temperature specific heat (Cp) of quasi-two-dimensional charge-density wave (CDW) compound KMo6O17 has been studied by a relaxation method from 2to48K under zero and 12T magnetic fields. The results show that no specific heat anomaly is found at 16K under both zero and 12T magnetic fields, although an anomaly is clearly observed in the resistivity and magnetoresistance measurements. From the data between 2 and 4K , the density of states at Fermi level is estimated as 0.2eV-1permolecule and the Debye temperature is extracted to be 418K . A bump appearing in Cp/T3 is found between 4 and 48K centered around 12.5-15K , indicating that the phason excitations contribute to the total specific heat similarly as in quasi-one-dimensional CDW conductors. Using a modified Debye model, a pinning frequency of 0.73THz for KMo6O17 is estimated from the phason contribution.

The effective temperatures and colours of G and K stars

International Nuclear Information System (INIS)

Bell, R.A.; Gustafsson, B.

1989-01-01

Temperature scales are found for G and K dwarf and giant stars, using new tables of synthetic infrared colours as well as the infrared flux ratio method. The temperatures of 95 individual stars are given. The colours are presented for grids of flux constant, line blanketed models. One grid has been published previously, as have some colours for the visible region of the spectrum. The models of this grid are in the range 4000 K eff < 6000 K, 0.75 < log g < 3.00, - 3.0 < [A/H] < 0.0. A grid of dwarf models, with the same temperature and abundance range but with 3.75 < log g < 4.5 is also used. The colours are computed from two series of overlapping synthetic spectra, which have been calculated with a resolution of 0.1 A between 3000 and 12 000 A and 1.0 A between 0.9 and 6.0 μm. (author)

STELLAR DIAMETERS AND TEMPERATURES. II. MAIN-SEQUENCE K- AND M-STARS

Energy Technology Data Exchange (ETDEWEB)

Boyajian, Tabetha S.; McAlister, Harold A.; Jones, Jeremy; White, Russel; Henry, Todd; Gies, Douglas; Jao, Wei-Chun; Parks, J. Robert [Center for High Angular Resolution Astronomy and Department of Physics and Astronomy, Georgia State University, P.O. Box 4106, Atlanta, GA 30302-4106 (United States); Von Braun, Kaspar; Kane, Stephen R.; Ciardi, David [NASA Exoplanet Science Institute, California Institute of Technology, MC 100-22, Pasadena, CA 91125 (United States); Van Belle, Gerard [Lowell Observatory, Flagstaff, AZ 86001 (United States); Ten Brummelaar, Theo A.; Schaefer, Gail; Sturmann, Laszlo; Sturmann, Judit [The CHARA Array, Mount Wilson Observatory, Mount Wilson, CA 91023 (United States); Muirhead, Philip S. [Department of Astronomy, California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, CA 91125 (United States); Lopez-Morales, Mercedes [Institut de Ciencies de L' Espai (CSIC-IEEC), E-08193 Bellaterra (Spain); Ridgway, Stephen [National Optical Astronomy Observatory, P.O. Box 26732, Tucson, AZ 85726-6732 (United States); Rojas-Ayala, Barbara [Department of Astrophysics, Division of Physical Sciences, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States); and others

2012-10-01

We present interferometric angular diameter measurements of 21 low-mass, K- and M-dwarfs made with the CHARA Array. This sample is enhanced by adding a collection of radius measurements published in the literature to form a total data set of 33 K-M-dwarfs with diameters measured to better than 5%. We use these data in combination with the Hipparcos parallax and new measurements of the star's bolometric flux to compute absolute luminosities, linear radii, and effective temperatures for the stars. We develop empirical relations for {approx}K0 to M4 main-sequence stars that link the stellar temperature, radius, and luminosity to the observed (B - V), (V - R), (V - I), (V - J), (V - H), and (V - K) broadband color index and stellar metallicity [Fe/H]. These relations are valid for metallicities ranging from [Fe/H] = -0.5 to +0.1 dex and are accurate to {approx}2%, {approx}5%, and {approx}4% for temperature, radius, and luminosity, respectively. Our results show that it is necessary to use metallicity-dependent transformations in order to properly convert colors into stellar temperatures, radii, and luminosities. Alternatively, we find no sensitivity to metallicity on relations we construct to the global properties of a star omitting color information, e.g., temperature-radius and temperature-luminosity. Thus, we are able to empirically quantify to what order the star's observed color index is impacted by the stellar iron abundance. In addition to the empirical relations, we also provide a representative look-up table via stellar spectral classifications using this collection of data. Robust examinations of single star temperatures and radii compared to evolutionary model predictions on the luminosity-temperature and luminosity-radius planes reveal that models overestimate the temperatures of stars with surface temperatures <5000 K by {approx}3%, and underestimate the radii of stars with radii <0.7 R{sub Sun} by {approx}5%. These conclusions additionally

A zero-dimensional EXTRAP computer code

International Nuclear Information System (INIS)

Karlsson, P.

1982-10-01

A zero-dimensional computer code has been designed for the EXTRAP experiment to predict the density and the temperature and their dependence upon paramenters such as the plasma current and the filling pressure of neutral gas. EXTRAP is a Z-pinch immersed in a vacuum octupole field and could be either linear or toroidal. In this code the density and temperature are assumed to be constant from the axis up to a breaking point from where they decrease linearly in the radial direction out to the plasma radius. All quantities, however, are averaged over the plasma volume thus giving the zero-dimensional character of the code. The particle, momentum and energy one-fluid equations are solved including the effects of the surrounding neutral gas and oxygen impurities. The code shows that the temperature and density are very sensitive to the shape of the plasma, flatter profiles giving higher temperatures and densities. The temperature, however, is not strongly affected for oxygen concentration less than 2% and is well above the radiation barrier even for higher concentrations. (Author)

Improved production of Br atoms near zero speed by photodissociating laser aligned Br2 molecules.

Science.gov (United States)

Deng, L Z; Yin, J P

2014-10-28

We theoretically investigated the improvement on the production rate of the decelerated bromine (Br) atoms near zero speed by photodissociating laser aligned Br2 precursors. Adiabatic alignment of Br2 precursors exposed to long laser pulses with duration on the order of nanoseconds was investigated by solving the time-dependent Schrödinger equation. The dynamical fragmentation of adiabatically aligned Br2 precursors was simulated and velocity distribution of the Br atoms produced was analyzed. Our study shows that the larger the degree of the precursor alignment, ⟨cos(2) θ⟩, the higher the production rate of the decelerated Br atoms near zero speed. For Br2 molecules with an initial rotational temperature of ~1 K, a ⟨cos(2) θ⟩ value of ~0.88 can result in an improvement factor of over ~20 on the production rate of the decelerated Br atoms near zero speed, requiring a laser intensity of only ~1 × 10(12) W/cm(2) for alignment.

Zeros of Wronskians of Hermite polynomials and Young diagrams

Science.gov (United States)

Felder, G.; Hemery, A. D.; Veselov, A. P.

2012-12-01

For a certain class of partitions, a simple qualitative relation is observed between the shape of the Young diagram and the pattern of zeros of the Wronskian of the corresponding Hermite polynomials. In the case of the two-term Wronskian W(Hn,Hn+k), we give an explicit formula for the asymptotic shape of the zero set as n→∞. Some empirical asymptotic formulas are given for the zero sets of three-term and four-term Wronskians.

Two-stage high frequency pulse tube refrigerator with base temperature below 10 K

Science.gov (United States)

Chen, Liubiao; Wu, Xianlin; Liu, Sixue; Zhu, Xiaoshuang; Pan, Changzhao; Guo, Jia; Zhou, Yuan; Wang, Junjie

2017-12-01

This paper introduces our recent experimental results of pulse tube refrigerator driven by linear compressor. The working frequency is 23-30 Hz, which is much higher than the G-M type cooler (the developed cryocooler will be called high frequency pulse tube refrigerator in this paper). To achieve a temperature below 10 K, two types of two-stage configuration, gas coupled and thermal coupled, have been designed, built and tested. At present, both types can achieve a no-load temperature below 10 K by using only one compressor. As to gas-coupled HPTR, the second stage can achieve a cooling power of 16 mW/10K when the first stage applied a 400 mW heat load at 60 K with a total input power of 400 W. As to thermal-coupled HPTR, the designed cooling power of the first stage is 10W/80K, and then the temperature of the second stage can get a temperature below 10 K with a total input power of 300 W. In the current preliminary experiment, liquid nitrogen is used to replace the first coaxial configuration as the precooling stage, and a no-load temperature 9.6 K can be achieved with a stainless steel mesh regenerator. Using Er3Ni sphere with a diameter about 50-60 micron, the simulation results show it is possible to achieve a temperature below 8 K. The configuration, the phase shifters and the regenerative materials of the developed two types of two-stage high frequency pulse tube refrigerator will be discussed, and some typical experimental results and considerations for achieving a better performance will also be presented in this paper.

A 13 kA current lead, measuring 1.5 m in length. The lower part consists of a high-temperature superconductor (Bi-2223), operating at between 50 K and 4.5 K, while the heat-exchanger upper part allows the current to be brought from room temperature to 50 K.

CERN Multimedia

2004-01-01

A 13 kA current lead, measuring 1.5 m in length. The lower part consists of a high-temperature superconductor (Bi-2223), operating at between 50 K and 4.5 K, while the heat-exchanger upper part allows the current to be brought from room temperature to 50 K.

Zero emission targets as long-term global goals for climate protection

International Nuclear Information System (INIS)

Rogelj, Joeri; Riahi, Keywan; Schaeffer, Michiel; Hare, William; Meinshausen, Malte; Knutti, Reto; Alcamo, Joseph

2015-01-01

Recently, assessments have robustly linked stabilization of global-mean temperature rise to the necessity of limiting the total amount of emitted carbon-dioxide (CO 2 ). Halting global warming thus requires virtually zero annual CO 2 emissions at some point. Policymakers have now incorporated this concept in the negotiating text for a new global climate agreement, but confusion remains about concepts like carbon neutrality, climate neutrality, full decarbonization, and net zero carbon or net zero greenhouse gas (GHG) emissions. Here we clarify these concepts, discuss their appropriateness to serve as a long-term global benchmark for achieving temperature targets, and provide a detailed quantification. We find that with current pledges and for a likely (>66%) chance of staying below 2 °C, the scenario literature suggests net zero CO 2 emissions between 2060 and 2070, with net negative CO 2 emissions thereafter. Because of residual non-CO 2 emissions, net zero is always reached later for total GHG emissions than for CO 2 . Net zero emissions targets are a useful focal point for policy, linking a global temperature target and socio-economic pathways to a necessary long-term limit on cumulative CO 2 emissions. (letter)

Temperature-dependent striped antiferromagnetism of LaFeAsO in a Green's function approach

International Nuclear Information System (INIS)

Liu Guibin; Liu Banggui

2009-01-01

We use a Green's function method to study the temperature-dependent average moment and magnetic phase-transition temperature of the striped antiferromagnetism of LaFeAsO, and other similar compounds, as the parents of FeAs-based superconductors. We consider the nearest and the next-nearest couplings in the FeAs layer, and the nearest coupling for inter-layer spin interaction. The dependence of the transition temperature T N and the zero-temperature average spin on the interaction constants is investigated. We obtain an analytical expression for T N and determine our temperature-dependent average spin from zero temperature to T N in terms of unified self-consistent equations. For LaFeAsO, we obtain a reasonable estimation of the coupling interactions with the experimental transition temperature T N = 138 K. Our results also show that a non-zero antiferromagnetic (AFM) inter-layer coupling is essential for the existence of a non-zero T N , and the many-body AFM fluctuations reduce substantially the low-temperature magnetic moment per Fe towards the experimental value. Our Green's function approach can be used for other FeAs-based parent compounds and these results should be useful to understand the physical properties of FeAs-based superconductors.

Electrical conductivity of molten SnCl{sub 2} at temperature as high as 1314 K

Energy Technology Data Exchange (ETDEWEB)

Salyulev, Alexander B.; Potapov, Alexei M. [Ural Branch of RAS, Ekaterinburg (Russian Federation). Inst. of High-Temperature Electrochemistry

2015-07-01

The electrical conductivity of molten SnCl{sub 2} was measured in a wide temperature range (ΔT=763 K), from 551 K to temperature as high as 1314 K, that is, 391 above the boiling point of the salt. The specific electrical conductance was found to reach its maximum at 1143 K, after that it decreases with the temperature rising.

Plastic behaviour of Zircaloy-4 in the temperature range 77-1000 K

International Nuclear Information System (INIS)

Derep, J.L.; Ibrahim, S.; Rouby, D.; Fantozzi, G.; Gobin, P.

1979-01-01

Tensile tests were carried out on Zircaloy-4 over a temperature range 77-1000 K. So, we have determined the flow stress variations as a function of temperature and strain rate. Two thermally activated zones were observed between about 77 and 600 K, a plateau stress between 600 and 700 K and an other thermally activated zone above 700 K. The various mechanisms which can be responsible for the thermally activated and athermal zones are discussed in the light of experimental results. The mechanical behaviour of Zircaloy-4 appears similar to the zirconium-oxygen alloys one. (orig.) [de

Enthalpy increment measurements of NaCrO2 using a high temperature Calvet calorimeter

International Nuclear Information System (INIS)

Iyer, V.S.; Jayanthi, K.; Ramarao, G.A.; Venugopal, V.; Sood, D.D.

1991-01-01

Enthalpy increment measurements on NaCrO 2 (s) were carried out in the temperature range 323 to 839 K using a high temperature Calvet micro calorimeter. The enthalpy increment values were least-squares fitted with temperature with the constraint that (Hdeg T - Hdeg 298 ) at 298.18 K equals zero, and can be given by: (Hdeg T - Hdeg 298 ) J/mol) ± 336 = -23515 + 75.364T(K) + 0.01256T 2 (K) (323 to 839 K). The first differential of the above equation with temperature gives the constant pressure molar heat capacity of NaCrO 2 (s), which is given by: Cdeg p (NaCrO 2 , s, T) (J/K mol) = 75.364 + 0.02512T(K). The thermal properties of NaCrO 2 (s) were calculated using the molar heat capacities from the present study and Sdeg(298 K) from the literature. (orig.)

Effect of the Solvent Temperatures on Dynamics of Serine Protease Proteinase K

Directory of Open Access Journals (Sweden)

Peng Sang

2016-02-01

Full Text Available To obtain detailed information about the effect of the solvent temperatures on protein dynamics, multiple long molecular dynamics (MD simulations of serine protease proteinase K with the solute and solvent coupled to different temperatures (either 300 or 180 K have been performed. Comparative analyses demonstrate that the internal flexibility and mobility of proteinase K are strongly dependent on the solvent temperatures but weakly on the protein temperatures. The constructed free energy landscapes (FELs at the high solvent temperatures exhibit a more rugged surface, broader spanning range, and higher minimum free energy level than do those at the low solvent temperatures. Comparison between the dynamic hydrogen bond (HB numbers reveals that the high solvent temperatures intensify the competitive HB interactions between water molecules and protein surface atoms, and this in turn exacerbates the competitive HB interactions between protein internal atoms, thus enhancing the conformational flexibility and facilitating the collective motions of the protein. A refined FEL model was proposed to explain the role of the solvent mobility in facilitating the cascade amplification of microscopic motions of atoms and atomic groups into the global collective motions of the protein.

Thermometry using 1/8 W carbon resistors in a temperature region around 10 mK

International Nuclear Information System (INIS)

Kobayasi, S.; Shinohara, M.; Ono, K.

1976-01-01

The resistance-temperature characteristics of 1/8 W carbon resistors of grade ERC-18SG, manufactured by Matsushita, with the nominal values of 48, 82, 100, 220 and 330 Ω have been measured in the region 4.2 K to 25 mK and their application as thermometers in this region is confirmed. For the 82 Ω resistor, measurements were taken at temperatures below 10mK. The temperature dependence of the resistance was found to be linear on the log-log plot over a wide range below 50 mK. The sensitivity remains finite even at 6 mK, but below 10 mK rapid measurements were prevented by a considerable increase in the thermal relaxation time. Measurement of the characteristics of several 100 Ω resistors from two different sets showed that resistors from the same set separate into two groups with different characteristics. This become appreciable at temperatures below 4.2 K, so it is difficult to predict the behaviour of Matsushite resistors below 4.2 K from the characteristics at higher temperatures. (author)

In-situ temperature calibration below 1 K using the μ+ Knight shift in CMN

International Nuclear Information System (INIS)

Heffner, R.H.; Le, L.P.; Amato, A.; Baines, C.

1996-01-01

The authors present μ + paramagnetic shift measurements between 12 K and about 65 mK in cerium magnesium nitrate (CMN) to investigate its utility as an in-situ temperature calibration source for low temperature μSR experiments. CMN is a salt which exhibits Curie-law susceptibility to temperatures as low as 5 mK. The μ + Knight shift is measured to be (1.46 ± 0.03) x 10 -3 /T + (0.004 ± 0.02) x 10 -3 , corresponding to a transferred hyperfine field of -28.5 kOe/μ B

Zero-temperature renormalization method for quantum systems. I. Ising model in a transverse field in one dimension

International Nuclear Information System (INIS)

Jullien, R.; Pfeuty, P.; Fields, J.N.; Doniach, S.

1978-01-01

A zero-temperature real-space renormalization-group method is presented and applied to the quantum Ising model with a transverse field in one dimension. The transition between the low-field and high-field regimes is studied. Magnetization components, spin correlation functions, and critical exponents are derived and checked against the exact results. It is shown that increasing the size of the blocks in the iterative procedure yields more accurate results, especially for the critical ''magnetic'' exponents near the transition

Critical behavior of 3D Z(N) lattice gauge theories at zero temperature

International Nuclear Information System (INIS)

Borisenko, O.; Chelnokov, V.; Cortese, G.; Gravina, M.; Papa, A.; Surzhikov, I.

2014-01-01

Three-dimensional Z(N) lattice gauge theories at zero temperature are studied for various values of N. Using a modified phenomenological renormalization group, we explore the critical behavior of the generalized Z(N) model for N=2,3,4,5,6,8. Numerical computations are used to simulate vector models for N=2,3,4,5,6,8,13,20 for lattices with linear extension up to L=96. We locate the critical points of phase transitions and establish their scaling with N. The values of the critical indices indicate that the models with N>4 belong to the universality class of the three-dimensional XY model. However, the exponent α derived from the heat capacity is consistent with the Ising universality class. We discuss a possible resolution of this puzzle

Critical behavior of 3D Z(N) lattice gauge theories at zero temperature

Energy Technology Data Exchange (ETDEWEB)

Borisenko, O., E-mail: oleg@bitp.kiev.ua [Bogolyubov Institute for Theoretical Physics, National Academy of Sciences of Ukraine, 03680 Kiev (Ukraine); Chelnokov, V., E-mail: chelnokov@bitp.kiev.ua [Bogolyubov Institute for Theoretical Physics, National Academy of Sciences of Ukraine, 03680 Kiev (Ukraine); Cortese, G., E-mail: cortese@unizar.es [Instituto de Física Teórica UAM/CSIC, Cantoblanco, E-28049 Madrid (Spain); Departamento de Física Teórica, Universidad de Zaragoza, E-50009 Zaragoza (Spain); Gravina, M., E-mail: gravina@cs.infn.it [Dipartimento di Fisica, Università della Calabria, and Istituto Nazionale di Fisica Nucleare, Gruppo Collegato di Cosenza, I-87036 Arcavacata di Rende, Cosenza (Italy); Papa, A., E-mail: papa@cs.infn.it [Dipartimento di Fisica, Università della Calabria, and Istituto Nazionale di Fisica Nucleare, Gruppo Collegato di Cosenza, I-87036 Arcavacata di Rende, Cosenza (Italy); Surzhikov, I., E-mail: i_van_go@inbox.ru [Bogolyubov Institute for Theoretical Physics, National Academy of Sciences of Ukraine, 03680 Kiev (Ukraine)

2014-02-15

Three-dimensional Z(N) lattice gauge theories at zero temperature are studied for various values of N. Using a modified phenomenological renormalization group, we explore the critical behavior of the generalized Z(N) model for N=2,3,4,5,6,8. Numerical computations are used to simulate vector models for N=2,3,4,5,6,8,13,20 for lattices with linear extension up to L=96. We locate the critical points of phase transitions and establish their scaling with N. The values of the critical indices indicate that the models with N>4 belong to the universality class of the three-dimensional XY model. However, the exponent α derived from the heat capacity is consistent with the Ising universality class. We discuss a possible resolution of this puzzle.

Proposed Use of Zero Bias Diode Arrays as Thermal Electric Noise Rectifiers and Non-Thermal Energy Harvesters

Science.gov (United States)

Valone, Thomas F.

2009-03-01

The well known built-in voltage potential for some select semiconductor p-n junctions and various rectifying devices is proposed to be favorable for generating DC electricity at "zero bias" (with no DC bias voltage applied) in the presence of Johnson noise or 1/f noise which originates from the quantum vacuum (Koch et al., 1982). The 1982 Koch discovery that certain solid state devices exhibit measurable quantum noise has also recently been labeled a finding of dark energy in the lab (Beck and Mackey, 2004). Tunnel diodes are a class of rectifiers that are qualified and some have been credited with conducting only because of quantum fluctuations. Microwave diodes are also good choices since many are designed for zero bias operation. A completely passive, unamplified zero bias diode converter/detector for millimeter (GHz) waves was developed by HRL Labs in 2006 under a DARPA contract, utilizing a Sb-based "backward tunnel diode" (BTD). It is reported to be a "true zero-bias diode." It was developed for a "field radiometer" to "collect thermally radiated power" (in other words, 'night vision'). The diode array mounting allows a feed from horn antenna, which functions as a passive concentrating amplifier. An important clue is the "noise equivalent power" of 1.1 pW per root hertz and the "noise equivalent temperature difference" of 10° K, which indicate sensitivity to Johnson noise (Lynch, et al., 2006). There also have been other inventions such as "single electron transistors" that also have "the highest signal to noise ratio" near zero bias. Furthermore, "ultrasensitive" devices that convert radio frequencies have been invented that operate at outer space temperatures (3 degrees above zero point: 3° K). These devices are tiny nanotech devices which are suitable for assembly in parallel circuits (such as a 2-D array) to possibly produce zero point energy direct current electricity with significant power density (Brenning et al., 2006). Photovoltaic p-n junction

Electrical conductivity of molten CdCl2 at temperatures as high as 1474 K

International Nuclear Information System (INIS)

Salyulev, Alexander B.; Potapov, Alexei M.

2016-01-01

The electrical conductivity of molten CdCl 2 was measured across a wide temperature range (ΔT=628 K), from 846 K to as high as 1474 K, i.e. 241 above the normal boiling point of the salt. In previous studies, a maximum temperature of 1201 K was reached, this being 273 lower than in the present work. The activation energy of electrical conductivity was calculated.

Zero-field magnetic response functions in Landau levels

Science.gov (United States)

Gao, Yang; Niu, Qian

2017-07-01

We present a fresh perspective on the Landau level quantization rule; that is, by successively including zero-field magnetic response functions at zero temperature, such as zero-field magnetization and susceptibility, the Onsager’s rule can be corrected order by order. Such a perspective is further reinterpreted as a quantization of the semiclassical electron density in solids. Our theory not only reproduces Onsager’s rule at zeroth order and the Berry phase and magnetic moment correction at first order but also explains the nature of higher-order corrections in a universal way. In applications, those higher-order corrections are expected to curve the linear relation between the level index and the inverse of the magnetic field, as already observed in experiments. Our theory then provides a way to extract the correct value of Berry phase as well as the magnetic susceptibility at zero temperature from Landau level fan diagrams in experiments. Moreover, it can be used theoretically to calculate Landau levels up to second-order accuracy for realistic models.

Dipolon theory of energy gap parameters at finite temperature and transition temperatures Tc and T* in high-temperature superconductors

International Nuclear Information System (INIS)

Sharma, R.R.

2006-01-01

First temperature dependent regular and pseudo-energy gap parameters and regular and pseudo-transition temperatures arising from the same physical origin have been calculated in the strong coupling formalism. Temperature dependent many-body field-theoretic techniques have been developed, as an extension of our previous zero-temperature formalism, to derive temperature dependent general expressions for the renormalized energy gap parameter Δ(k->,ω), the gap renormalization parameter Z(k->,ω) and energy band renormalization parameter χ(k->,ω) for momentum k-> and frequency ω making use of dipolon propagator and electron Green's function taking into account explicitly the dressed dipolons as mediators of superconductivity, the screened Coulomb repulsion and nonrigid electron energy bands considering retardation and damping effects and electron-hole asymmetry. The theory takes into account all necessary and important correlations. Our self-consistent calculations utilize the previously symmetry predicted two energy gap parameters for superconducting cuprates, one being antisymmetric (''as'') with respect to the exchange of the k x and k y components of vector k-> and the other being symmetric (''s'') with respect to the exchange of k x and k y . Our present temperature dependent self-consistent solutions of the real and imaginary parts of the Δ(k->,ω), Z(k->,ω) and χ(k->,ω) confirm the existence of these two (different) solutions and conclude that the antisymmetric solution of the gap parameter corresponds to the observed regular (''reg'') superconducting energy gap whereas the symmetric solution corresponds to the observed pseudo-(''pse-'') energy gap. Explicit temperature dependent self-consistent calculations have been performed here for Bi 2 Sr 2 CaCu 2 O 8+δ as well as Bi 2 Sr 2 CaCu 2 O 8 giving temperature dependent energy gap parameters and corresponding transition temperatures. The calculated results are consistent with the available experimental

High-capacity NO2 denuder systems operated at various temperatures (298-473 K).

Science.gov (United States)

Wolf, Jan-Christoph; Niessner, Reinhard

2012-12-01

In this study, we investigated several coatings for high-temperature, high-capacity, and high-efficiency denuder-based NO(2) removal, with the scope to face the harsh conditions and requirements of automotive exhaust gas sampling. As first coating, we propose a potassium iodide (KI)/polyethylene glycol coating with a high removal efficiency (ε > 98%) for about 2 h and 50 ppm NO(2) at room temperature (298 K). At elevated temperatures (423 K), the initial capacity (100 ppmh) is decreased to 15 ppmh. Furthermore, this is the first proposal of the ionic liquid methyl-butyl-imidazolium iodide ([BMIm(+)][I(-)]) as denuder coating material. At room temperature, this ionic liquid exhibits far greater capacity (300 ppmh) and NO(2) removal efficiency (ε > 99.9%) than KI. Nevertheless, KI exhibits a slightly (~10%) higher capacity at elevated temperatures than [BMIm(+)][I(-)]. Both coatings presented are suitable for applications requiring selective denuding of NO(2) at temperatures up to 423 K.

Zero temperature renormalisation group study of the random systems: The Ising model in a transverse field in two dimensions

International Nuclear Information System (INIS)

Kamieniarz, G.

1984-12-01

A zero temperature real space renormalization group block method is applied to the random quantum Ising model with a transverse field on the planar honeycomb and square lattices. For the bond diluted system the magnetisation and the separation of the ground state energy level (in the paramagnetic phase) are presented for several bond concentrations p. The critical exponents extracted both from the fixed-points and from direct numerical computations preserve some scaling relations, and the critical curve displays a characteristic discontinuity at the percolation concentration. For the McCoy and Wu distribution the random fields and bonds are found to introduce a strong relevant disorder. The order parameter still falls off continuously to zero for well-defined values of the parameters, but a new fixed point yields a slight change in the critical exponents. (author)

Thermoelectric Properties of High-Doped Silicon from Room Temperature to 900 K

Science.gov (United States)

Stranz, A.; Kähler, J.; Waag, A.; Peiner, E.

2013-07-01

Silicon is investigated as a low-cost, Earth-abundant thermoelectric material for high-temperature applications up to 900 K. For the calculation of module design the Seebeck coefficient and the electrical as well as thermal properties of silicon in the high-temperature range are of great importance. In this study, we evaluate the thermoelectric properties of low-, medium-, and high-doped silicon from room temperature to 900 K. In so doing, the Seebeck coefficient, the electrical and thermal conductivities, as well as the resulting figure of merit ZT of silicon are determined.

Getting to zero - Experiences of designing and monitoring a zero-energy-building: The Science House in Minnesota

Energy Technology Data Exchange (ETDEWEB)

Steinbock, Jason; McDougall, Tom; Eijadi, David; Weier, Jeff [The Weidt Group, Minnetonka, MN (United States)

2005-07-01

The challenge of the Science House at the Science Museum of Minnesota was to create habitable, cold climate architecture that would result in a zero net energy building. The team used science to exert an authoritative influence to resolve design conflicts-at the intersections of functionality, aesthetics and performance. The team needed to significantly reduce annual energy consumption beginning with expectations of use and architectural form. Ultimately, renewable generation would be needed. The defining question became 'how much building and power generation can we build with the given budget?' The resulting building utilizes passive solar design, daylighting, ground source heat pumps and photovoltaic (PV) panels as the major design strategies. This poster documents the predicted energy use and actual monitored performance. It shows the extent of load reduction achieved with passive solar design. A challenge for getting to 'real zero' is the difference between expected performance and actual building performance. This poster illustrates how measured data is used to trace the causes to unexpected equipment performance, heat pump behaviour and off-line PV panels. Assumptions regarding occupancy and building use during the design phase often differ from their actual use; this makes operating a building for zero energy an additional challenge above and beyond designing one. Overall, the actual building is exceeding the design team's goals, using on average 59 kWh/m{sup 2} annually and generating 80 kWh/m{sup 2} to exceed even the zero net energy goals.

Electrical conductivity of molten ZnCl2 at temperature as high as 1421 K

International Nuclear Information System (INIS)

Salyulev, Alexander B.; Potapov, Alexei M.

2015-01-01

The electrical conductivity of molten ZnCl 2 was measured in a wide temperature range (ΔT=863 K) to a temperature as high as 1421 K that is 417 degrees above the boiling point of the salt. At the temperature maximum of the own vapor pressure of the salt reached several megapascals.

Low-temperature current-voltage characteristics of MIS Cu/n-GaAs and inhomogeneous Cu/n-GaAs Schottky diodes

Energy Technology Data Exchange (ETDEWEB)

Biber, M

2003-01-01

The current-voltage (I-V) characteristics of metal-insulating layer-semiconductor Cu/n-GaAs and inhomogeneous Cu/n-GaAs Schottky barrier diodes were determined in the temperature range 80-300 K. The evaluation of the experimental I-V data reveals a nonlinear increase of the zero-bias barrier height (qPHI{sub 0}) for the inhomogeneous Cu/n-GaAs Schottky barrier diodes and a linear increase of the zero-bias barrier height (qPHI{sub 0}) for Cu/n-GaAs Schottky barrier diodes with an interfacial layer. The ideality factor n decreases with increasing temperature for all diodes. Furthermore, the changes in PHI{sub 0} and n become quite significant below 150 K and the plot of ln(I{sub 0}/T{sup 2}) versus 1/T exhibits a non-linearity below 180 K for the inhomogeneous barrier diodes. Such behavior is attributed to barrier inhomogeneities by assuming a Gaussian distribution of barrier heights at the interface. The value of the Richardson constant was found to be 5.033 A/cm{sup 2} K{sup 2}, which is close to the theoretical value of 8.16 A/cm{sup 2} K{sup 2} used for the determination of the zero-bias barrier height.

Development of the active magnetic regenerative refrigerator operating between 77 K and 20 K with the conduction cooled high temperature superconducting magnet

Science.gov (United States)

Park, Inmyong; Jeong, Sangkwon

2017-12-01

The experimental investigation of an active magnetic regenerative refrigerator (AMRR) operating between 77 K and 20 K is discussed in this paper, with detailed energy transfer analysis. A multi-layered active magnetic regenerator (AMR) is used, which consists of four different rare earth intermetallic compounds in the form of irregular powder. Numerical simulation confirms that the AMR can attain its target operating temperature range. Magnetic field alternation throughout the AMR is generated by a high temperature superconducting (HTS) magnet. The HTS magnet is cooled by a two stage Gifford-McMahon (GM) cryocooler. Helium gas was employed as a working fluid and its oscillating flow in the AMR is controlled in accordance with the magnetic field variation. The AMR is divided into two stages and each stage has a different mass flow rate as needed to achieve the desired cooling performance. The temperature variation of the AMR during the experiment is monitored by temperature sensors installed inside the AMR. The experimental results show that the AMRR is capable of achieving no-load temperature of 25.4 K while the warm end temperature is 77 K. The performance of the AMRR is analyzed by observing internal temperature variations at cyclic steady state. Furthermore, numerical estimation of the cooling capacity and the temperature variation of the AMR are examined and compared with the experimental results.

Thermophysical properties of multi-wall carbon nanotube bundles at elevated temperatures up to 830 K

International Nuclear Information System (INIS)

Wang, Xinwei; Wang, Jianmei; Huang, Xiaopeng; Eres, Gyula

2011-01-01

In this paper we discuss the results of thermal transport measurements in multi-wall carbon nanotube (MWCNT) bundles at elevated temperatures. A novel generalized electrothermal technique (GET) was developed for measuring the thermal diffusivity ( ) and conductivity (k) of MWCNT bundles. The results show that the feeding current has a negligible effect on the thermal properties. The measured k is larger than the reported values for unaligned bundles, and is comparable to that of typical aligned arrays. Compared with experimental and theoretical data for individual CNTs, k of the MWCNT bundles is two to three orders of magnitude lower, suggesting that the thermal transport in CNT bundles is dominated by the thermal contact resistance of tube-to-tube junctions. The effective density for the two MWCNT bundles, which is difficult to measure using other techniques, was determined to be 116 kg/m3 and 234 kg/m3, respectively. The temperature dependences of and k at temperatures up to 830 K was obtained. slightly decreases with temperature while k exhibits a small increase with temperature up to 500 K and then decreases. For the first time, the behavior of specific heat cp(T) for CNTs above room temperature was determined. The specific heat is close to graphite at 300-400 K but is lower than that for graphite above 400 K, indicating that the behavior of phonons in MWCNT bundles is dominated by boundary scattering rather than by the three-phonon Umklapp process. The length of the mean curvature between two adjacent tube contact points in these bundles is estimated to be on the order of micrometer to millimeter. The analysis of the radiation heat loss suggests that it needs to be considered when measuring the thermophysical properties of micro/nano wires of high aspect ratios at elevated temperatures, especially for individual CNTs due to their extremely small diameter.

Driving Curie temperature towards room temperature in the half-metallic ferromagnet K2Cr8O16 by soft redox chemistry.

Science.gov (United States)

Pirrotta, I; Fernández-Sanjulián, J; Moran, E; Alario-Franco, M A; Gonzalo, E; Kuhn, A; García-Alvarado, F

2012-02-14

The half-metallic ferromagnet K(2)Cr(8)O(16) with the hollandite structure has been chemically modified using soft chemistry methods to increase the average oxidation state of chromium. The synthesis of the parent material has been performed under high pressure/high temperature conditions. Following this, different redox reactions have been carried out on K(2)Cr(8)O(16). Oxidation to obtain potassium-de-inserted derivatives, K(2-x)Cr(8)O(16) (0 ≤x≤ 1), has been investigated with electrochemical methods, while the synthesis of sizeable amounts was achieved chemically by using nitrosonium tetrafluoroborate as a highly oxidizing agent. The maximum amount of extracted K ions corresponds to x = 0.8. Upon oxidation the hollandite structure is maintained and the products keep high crystallinity. The de-insertion of potassium changes the Cr(3+)/Cr(4+) ratio, and therefore the magnetic properties. Interestingly, the Curie temperature increases from ca. 175 K to 250 K, getting therefore closer to room temperature.

The bimolecular reaction of radiolysis product of hydrated electron at temperature up to 473K; Reaksi bimolekular antar produk radiolisis elektron terhidrasi pada temperatur hingga 473K

Energy Technology Data Exchange (ETDEWEB)

Sunaryo, G R [Reactor Safety Technology Research Centre, National Atomic Energy Agency, Serpong (Indonesia)

1996-06-01

Rate constant from the bimolecular reaction of hydrated electron was determined by using radiolysis method. The methanol solution with concentration of 5 x 10{sup -2} dm{sup 3} mol{sup -1} was used as a scavenger of H and OH radicals. The pH was kept by adding the buffer solution of 1.0 x 10{sup -3} dm{sup 3} mol{sup -1} Na{sub 2}HPO{sub 4} + 1.0 x 10{sup 4} dm{sup 3} mol{sup -1} NaH{sub 2}PO{sub 4}. The irradiation was done by using the electron beam which come from linear accelerator 28 MeV with pulse width 10ns and dose of 80 Gy per pulse. The absorbance of hydrated electron was observed at wavelength of 824 nm. By using the kinetic equation the rate reaction constants were obtained. The bimolecular reaction of hydrated electron increase with temperature up to 423K. The activation energy was 19.3 kJ mol{sup -1} and the 2 k (298K) was 1.1 x 10{sup 10} dm{sup 3} mol{sup -1}. Then this bimolecular reaction decrease at temperature higher than 423K and the rate reaction constant at 473K almost similar with that at 298K. (author)

(p, ρ, T) Properties for n-butane in the temperature range from 280 K to 380 K at pressures up to 200 MPa

International Nuclear Information System (INIS)

Miyamoto, H.; Uematsu, M.

2007-01-01

The (p, ρ, T) properties for n-butane in the compressed liquid phase were measured by means of a metal-bellows variable volumometer in the temperature range from 280 K to 380 K at pressures up to 200 MPa. The mole fraction purity of the n-butane used in the measurements was 0.9997. The expanded uncertainties (k = 2) in temperature, pressure, and density measurements have been estimated to be less than ±3 mK; 1.4 kPa (p ≤ 7 MPa), 0.06% (7 MPa 150 MPa); and 0.09%, respectively. In the region above100 MPa at T = 280 K and T = 440 K, the uncertainty in density measurements increases from 0.09% to 0.13% and 0.22%, respectively. Eight (p, ρ, T) measurements at the same temperatures and pressures as the literature values have been conducted for comparisons. In addition, comparisons of the available equations of state with the present measurements are reported

Temperature control for liquid-helium cryostats below 4.2 K

International Nuclear Information System (INIS)

Escorne, M.; Mauger, A.

1983-01-01

We report the operational characteristics of a membrane type of manostat and of a throttle valve system which we have constructed to regulate the pressure P above the liquid-helium bath. The choice of the manostat rather than the other device depends on the nature of the experiments to be performed: in the membrane type of manostat, the temperature is determined with an accuracy limited by the fluctuations ΔT around the mean value T. With throttle valves, the accuracy is limited by the drift of T in time. The performance of both devices prove to be sufficiently good as they stand, since the departure from T in the course of the experiments is lower than 10 -2 K in the whole range 1.4< T<4.2 K, being well inside this limit below 2 K. The need for expensive and complex electronic regulations to improve the temperature control is thus exceptional

Zeros of smallest modulus of functions resembling exp(z

Directory of Open Access Journals (Sweden)

Kenneth B. Stolarsky

1982-01-01

Full Text Available To determine (in various senses the zeros of the Laplace transform of a signed mass distribution is of great importance for many problems in classical analysis and number theory. For example, if the mass consists of finitely many atoms, the transform is an exponential polynomial. This survey studies what is known when the distribution is a probability density function of small variance, and examines in what sense the zeros must have large moduli. In particular, classical results on Bessel function zeros, of Szegö on zeros of partial sums of the exponential, of I. J. Schoenberg on k-times positive functions, and a result stemming from Graeffe's method, are all presented from a unified probabilistic point of view.

A rapid method for measuring maximum density temperatures in water and aqueous solutions for the study of quantum zero point energy effects in these liquids

International Nuclear Information System (INIS)

Deeney, F A; O'Leary, J P

2008-01-01

The connection between quantum zero point fluctuations and a density maximum in water and in liquid He 4 has recently been established. Here we present a description of a simple and rapid method of determining the temperatures at which maximum densities in water and aqueous solutions occur. The technique is such as to allow experiments to be carried out in one session of an undergraduate laboratory thereby introducing students to the concept of quantum zero point energy

Modelling of phase change materials in the Toronto SUI net zero energy house using TRNSYS

Energy Technology Data Exchange (ETDEWEB)

Siddiqui, O.; Fung, A.; Zhang, D. [Ryerson Polytechnic Univ., Toronto, ON (Canada). Dept. of Mechanical and Industrial Engineering

2008-08-15

In the context of building applications, phase change materials (PCM), can be defined as any heat storage material that can absorb a large amount of thermal energy while undergoing a change in phase, such as from a solid to a liquid phase. The incorporation of PCM into the building envelope can enhance occupant comfort through the reduction of indoor temperature fluctuations. It has also been shown to cause a decrease in the overall energy consumption associated with the heating and cooling of buildings. This paper extended the analysis of the impact of using PCM, which has traditionally focused on homes of ordinary construction, to incorporate low to zero energy homes using a model of the Toronto net zero energy house developed in TRNSYS. The paper provided a description of the TRNSYS model/methodology, with reference to the wall layer used in the net zero energy house, and model of the layout of the net zero energy house in TRYNSYS. The TRYNSYS/type 204 PCM component was also presented along with the simulation results in terms of the temperature profile of the third floor of the net zero energy house on a typical winter day with varying PCM concentrations; the temperature profile of the third floor of the net zero energy house on a typical summer day with varying PCM concentrations; yearly heating/cooling load requirements of the net zero energy house for a variety of thermal mass used; temperature profile of the third floor of the net zero energy house on a typical summer day when PCM and concrete slab was used; yearly temperature profile of the third floor of the net zero energy house, illustrating the impact of using PCM; and the yearly heating/cooling load of the net zero energy house as the concentration of PCM was varied. It was concluded that the use of building integrated PCM can reduce temperature fluctuations considerably in the summer but only slightly in the winter. 16 refs., 1 tab., 8 figs.

Integrals over products of distributions and coordinate independence of zero-temperature path integrals

International Nuclear Information System (INIS)

Kleinert, H.; Chervyakov, A.

2003-01-01

In perturbative calculations of quantum-statistical zero-temperature path integrals in curvilinear coordinates one encounters Feynman diagrams involving multiple temporal integrals over products of distributions, which are mathematically undefined. In addition, there are terms proportional to powers of Dirac δ-functions at the origin coming from the measure of path integration. We give simple rules for integrating products of distributions in such a way that the results ensure coordinate independence of the path integrals. The rules are derived by using equations of motion and partial integration, while keeping track of certain minimal features originating in the unique definition of all singular integrals in 1-ε dimensions. Our rules yield the same results as the much more cumbersome calculations in 1-ε dimensions where the limit ε→0 is taken at the end. They also agree with the rules found in an independent treatment on a finite time interval

K-band spectroscopic metallicities and temperatures of M-dwarf stars

Directory of Open Access Journals (Sweden)

Rojas-Ayala Bárbara

2013-04-01

Full Text Available I present the metallicity and effective temperature techniques developed for M dwarf stars by Rojas-Ayala et al. (2010, 2012. These techniques are based on absorption features present in the modest resolution K-band spectra (R∼2700 of M dwarfs and have been calibrated using FGK+M dwarf pairs and synthetic atmosphere models. The H2O-K2 index seems to overestimate the effective temperatures of M dwarfs when compared to interferometric measurements. The metallicity distribution of the M dwarf host candidates by the Kepler Mission hints that jovian-size planets form preferentially around solar and super-solar metallicity environments, while small rocky planet host exhibit a wide range of metallicities, just like in their solar-type counterparts.

Electrical conductivity of molten CdCl{sub 2} at temperatures as high as 1474 K

Energy Technology Data Exchange (ETDEWEB)

Salyulev, Alexander B.; Potapov, Alexei M. [Russian Academy of Sciences, Ekaterinburg (Russian Federation). Inst. of High-Temperature Electrochemistry

2016-11-01

The electrical conductivity of molten CdCl{sub 2} was measured across a wide temperature range (ΔT=628 K), from 846 K to as high as 1474 K, i.e. 241 above the normal boiling point of the salt. In previous studies, a maximum temperature of 1201 K was reached, this being 273 lower than in the present work. The activation energy of electrical conductivity was calculated.

Integration of auto analysis program of gamma spectrum and software and determination of element content in sample by k-zero method

International Nuclear Information System (INIS)

Trinh Quang Vinh; Truong Thi Hong Loan; Mai Van Nhon; Huynh Truc Phuong

2014-01-01

Integrating the gamma spectrum auto-analysis program with elemental analysis software by k-zero method is the objective for many researchers. This work is the first stepin building an auto analysis program of gamma spectrum, which includes modules of reading spectrum, displaying spectrum, calibrating energy of peak, smoothing spectrum, calculating peak area and determining content of elements in sample. Then, the results from the measurements of standard samples by a low level spectrometer using HPGe detector are compared to those of other gamma spectrum auto-analysis programs. (author)

Measurements of (p, ρ, T) properties for isobutane in the temperature range from 280 K to 440 K at pressures up to 200 MPa

International Nuclear Information System (INIS)

Miyamoto, H.; Uematsu, M.

2006-01-01

Measurements of (p, ρ, T) properties for isobutane in the compressed liquid phase have been obtained by means of a metal-bellows variable volumometer in the temperature range from 280 K to 440 K at pressures up to 200 MPa. The volume-fraction purity of isobutane used was 0.9999. The expanded uncertainties (k = 2) of temperature, pressure, and density measurements have been estimated to be less than 3 mK, 1.5 kPa (p ≤ 7 MPa), 0.06% (7 MPa 150 MPa), and 0.11%, respectively. In region more than 100 MPa at 280 K and 440 K, the uncertainty in density measurements rise up to 0.15% and 0.23%, respectively. The differences of the present density values at the same temperature between two series of measurements, in which the sample fillings are different, are within the maximum deviation of 0.09% in density, which is enough lower than the expanded uncertainty in density. Eight (p, ρ, T) measurements at the same temperatures and pressures as the literature values have been conducted for comparison. In addition, vapour pressures were measured at T = (280, 300) K. Moreover, the comparisons of the available equations of state with the present measurements are reported

Acoustic resonator providing fixed points of temperature between 0.1 and 2 K

International Nuclear Information System (INIS)

Salmela, Anssi; Tuoriniemi, Juha; Pentti, Elias; Sebedash, Alexander; Rysti, Juho

2009-01-01

Below 2 K the speed of second sound in mixtures of liquid 3 He and 4 He first increases to a maximum of 30-40 m/s at about 1 K and then decreases again at lower temperatures to values below 15 m/s. The exact values depend on the concentration and pressure of the mixture. This can be exploited to provide fixed points in temperature by utilizing a resonator with appropriate dimensions and frequency to excite standing waves in the resonator cavity filled with helium mixture. We demonstrate that commercially mass produced quartz tuning forks can be used for this purpose. They are meant for frequency standards operating at 32 kHz. Their dimensions are typically of order 1 mm matching the wavelength of the second sound in helium mixtures at certain values of temperature. Due to the complicated geometry, we observe some 20 sharp acoustic resonances in the range 0.1l 2 K having temperature resolution of order 1 μK. The quartz resonators are cheap, compact, simple to implement, easy to measure with great accuracy, and, above all, they are not sensitive to magnetic field, which is a great advantage compared to fixed point devices based on superconductivity transitions. The reproducibility of the resonance pattern upon thermal cycling remains to be verified.

Finite temperature system of strongly interacting baryons

International Nuclear Information System (INIS)

Bowers, R.L.; Gleeson, A.M.; Pedigo, R.D.; Wheeler, J.W.

1976-07-01

A fully relativistic finite temperature many body theory is constructed and used to examine the bulk properties of a system of strongly interacting baryons. The strong interactions are described by a two parameter phenomenological model fit to a simple description of nuclear matter at T = 0. The zero temperature equation of state for such a system which has already been discussed in the literature was developed to give a realistic description of nuclear matter. The model presented here is the exact finite temperature extension of that model. The effect of the inclusion of baryon pairs for T greater than or equal to 2mc 2 /k is discussed in detail. The phase transition identified with nuclear matter vanishes for system temperatures in excess of T/sub C/ = 1.034 x 10 11 0 K. All values of epsilon (P,T) correspond to systems that are causal in the sense that the locally determined speed of sound never exceeds the speed of light

Finite temperature system of strongly interacting baryons

Energy Technology Data Exchange (ETDEWEB)

Bowers, R.L.; Gleeson, A.M.; Pedigo, R.D.; Wheeler, J.W.

1976-07-01

A fully relativistic finite temperature many body theory is constructed and used to examine the bulk properties of a system of strongly interacting baryons. The strong interactions are described by a two parameter phenomenological model fit to a simple description of nuclear matter at T = 0. The zero temperature equation of state for such a system which has already been discussed in the literature was developed to give a realistic description of nuclear matter. The model presented here is the exact finite temperature extension of that model. The effect of the inclusion of baryon pairs for T greater than or equal to 2mc/sup 2//k is discussed in detail. The phase transition identified with nuclear matter vanishes for system temperatures in excess of T/sub C/ = 1.034 x 10/sup 11/ /sup 0/K. All values of epsilon (P,T) correspond to systems that are causal in the sense that the locally determined speed of sound never exceeds the speed of light.

The effect of temperature on pulsed positive streamer discharges in air over the range 292 K–1438 K

Science.gov (United States)

Ono, Ryo; Ishikawa, Yuta

2018-05-01

The effect of temperature on pulsed positive streamer discharges in air is measured by comparing atmospheric-pressure, high-temperature discharges with low-pressure, room-temperature discharges at the same air densities n and discharge voltages. Both discharges have the same reduced electric field E/n, so the differences between the two discharges only depend on the temperature, which is varied from 292 K to 1438 K. Temperature affects the discharge pulse energy most significantly; at 1438 K, the energy of an atmospheric-pressure discharge pulse is approximately 30 times larger than that of the corresponding 20.5 kPa, room-temperature discharge. Temperature also affects the shapes of the streamers when K, but no significant effect is observed for K. There is also no significant temperature effect on the spatially integrated intensity of N2(C–B) emission. However, temperature strongly affects the ratio of the integrated emission intensity to the discharge energy. No effect of the temperature is observed on the propagation velocity of the primary streamer or on the length of the secondary streamer.

Electrical conductivity of molten ZnCl{sub 2} at temperature as high as 1421 K

Energy Technology Data Exchange (ETDEWEB)

Salyulev, Alexander B.; Potapov, Alexei M. [RAS Ural Branch, Ekaterinburg. (Russian Federation) Institute of High-Temperature Electrochemistry

2015-07-01

The electrical conductivity of molten ZnCl{sub 2} was measured in a wide temperature range (ΔT=863 K) to a temperature as high as 1421 K that is 417 degrees above the boiling point of the salt. At the temperature maximum of the own vapor pressure of the salt reached several megapascals.

Thermodynamic properties of molybdenum borides at temperatures above 300 K

International Nuclear Information System (INIS)

Bolgar, A.S.; Blinder, A.V.; Serbova, M.I.

1990-01-01

Enthalpy of Mo 2 B, MoB, Mo 2 B 5 borides within the range of temperatures above 300 K has been experimentally studied. Parameters of temperature dependences of enthalpy, heat capacity, entropy and the reduced Gibbs energy of the studied substances are calculated within a wide range. It is stated that high-temperature heat capacity of the studied borides can be presented as a sum of the electron component, a harmonic part of the lattice component and a contribution caused by anharmonic oscillations of lattice atoms. Values of coefficients of isothermal compressibility of Mo 2 , MoB, Mo 2 B 5 within the high temperature range are estimated

A thermodynamically consistent quasi-particle model without temperature-dependent infinity of the vacuum zero point energy

International Nuclear Information System (INIS)

Cao Jing; Jiang Yu; Sun Weimin; Zong Hongshi

2012-01-01

In this Letter, an improved quasi-particle model is presented. Unlike the previous approach of establishing quasi-particle model, we introduce a classical background field (it is allowed to depend on the temperature) to deal with the infinity of thermal vacuum energy which exists in previous quasi-particle models. After taking into account the effect of this classical background field, the partition function of quasi-particle system can be made well-defined. Based on this and following the standard ensemble theory, we construct a thermodynamically consistent quasi-particle model without the need of any reformulation of statistical mechanics or thermodynamical consistency relation. As an application of our model, we employ it to the case of (2+1) flavor QGP at zero chemical potential and finite temperature and obtain a good fit to the recent lattice simulation results of Borsányi et al. A comparison of the result of our model with early calculations using other models is also presented. It is shown that our method is general and can be generalized to the case where the effective mass depends not only on the temperature but also on the chemical potential.

Thermodynamic constants of N-[tris(hydroxymethyl)methyl-3-amino]propanesulfonic acid (Taps) from the temperatures 278.15 K to 328.15 K

International Nuclear Information System (INIS)

Roy, Rabindra N.; Roy, Lakshmi N.; LeNoue, Sean R.; Denton, Cole E.; Simon, Ashley N.; Richards, Sarah J.; Moore, Andrew C.; Roy, Chandra N.; Redmond, R. Ryan; Bryant, Paul A.

2006-01-01

Values of the second thermodynamic dissociation constant pK 2 of N-[tris(hydroxymethyl)methyl-3-amino]propanesulfonic acid (Taps) have been determined at twelve temperatures from 278.15 K to 328.15 K including 310.15 K by measurements of the electromotive-force for cells without liquid junction of the type: Pt|H 2 (g, p - bar =101.325 kPa)|Taps (m 1 ), NaTapsate (m 2 ), NaCl (m 3 )|AgCl|Ag, where m denotes molality. The pK 2 values for the dissociation of Taps are represented by the equation: pK 2 =2969.61.(K/T) - 17.05052+2.73697.ln(T/K). The values of pK 2 for Taps were found to be (8.502+/-0.0007) at T=298.15 K and (8.225+/-0.0009) at T=310.15 K, respectively, indicating thereby to be useful as buffer solutions for pH control in the region 7.4 to 8.5. The thermodynamic quantities, ΔG - bar , ΔH - bar , ΔS - bar , and ΔC p - bar dissociation process of Taps have been derived from the temperature coefficients of the pK 2

A low-temperature (4-300K) constant volume gas thermometer

International Nuclear Information System (INIS)

Combarieu, A. de

1976-01-01

A constant volume gas thermometer was built to calibrate the various secondary thermometers used at low temperature. This gas thermometer is placed in a cryostat where any stable temperature between 4 and 300K may be obtained. The principle is outlined, then the gas thermometer and its auxiliary equipment are briefly described; the corrections to be applied to the results are given and a table shows the values obtained [fr

Superhigh Temperatures and Acoustic Cavitation

CERN Document Server

Belyaev, V B; Miller, M B; Sermyagin, A V; Topolnikov, A S

2003-01-01

The experimental results on thermonuclear synthesis under acoustic cavitation have been analyzed with the account of the latest data and their discussion. The analysis testifies that this avenue of research is a very promising one. The numerical calculations of the D(d, n)^{3}He reaction rate in the deuterated acetone (C_{3}D_{6}O) under the influence of ultrasound depending on T environment temperature within the range T=249-295 K have been carried out within the framework of hydrodynamic model. The results show that it is possible to improve substantially the effect/background relationship in experiments by decreasing the fluid temperature twenty-thirty degrees below zero.

The influence of temperature on selenate adsorption by goethite

Energy Technology Data Exchange (ETDEWEB)

Kersten, M.; Vlasova, N. [Mainz Univ. (Germany). Geosciences Inst.

2013-08-01

Acid-base batch titration data up to 75 C were used to constrain a temperature-dependent 1-pK basic Stern model of the surface protonation reactions of goethite. Experimental data for the temperature dependence of pH{sub PZC} (as determined using the two-term Van't Hoff extrapolation) yielded a negative value of -44.9 kJ/mol for the surface protonation enthalpy, and therefore a shift of the zero point of charge towards lower pH values with increasing temperature. Batch titrations at selenate concentrations of between 10 and 100 {mu}M showed an increased degree of adsorption in the acidic pH range, which appeared to be sensitive to the ionic strength of the solution. The selenate adsorption edges shifted towards more acidic pH values with increasing temperature. A 1-pK charge distribution multi-site surface complexation (CD-MUSIC) model was applied, assuming the formation of an outer-spheric surface complex together with an inner-spheric one, in agreement with published spectroscopic information. The temperature behaviour of the intrinsic equilibrium constants were well represented by a linear Van't Hoff log K vs. 1/T plot, from which negative enthalpy values could be derived for both adsorption reactions. The adsorption of the selenate was therefore exothermic and became weaker with increasing temperature. The bidentate inner-spheric complex was more sensitive to rises in temperature (-70 kJ/mol), compared to the outer-spheric complex (-36 kJ/mol). The latter ultimately became the dominating adsorption process at the highest temperature studied. (orig.)

The influence of temperature on selenate adsorption by goethite

International Nuclear Information System (INIS)

Kersten, M.; Vlasova, N.

2013-01-01

Acid-base batch titration data up to 75 C were used to constrain a temperature-dependent 1-pK basic Stern model of the surface protonation reactions of goethite. Experimental data for the temperature dependence of pH PZC (as determined using the two-term Van't Hoff extrapolation) yielded a negative value of -44.9 kJ/mol for the surface protonation enthalpy, and therefore a shift of the zero point of charge towards lower pH values with increasing temperature. Batch titrations at selenate concentrations of between 10 and 100 μM showed an increased degree of adsorption in the acidic pH range, which appeared to be sensitive to the ionic strength of the solution. The selenate adsorption edges shifted towards more acidic pH values with increasing temperature. A 1-pK charge distribution multi-site surface complexation (CD-MUSIC) model was applied, assuming the formation of an outer-spheric surface complex together with an inner-spheric one, in agreement with published spectroscopic information. The temperature behaviour of the intrinsic equilibrium constants were well represented by a linear Van't Hoff log K vs. 1/T plot, from which negative enthalpy values could be derived for both adsorption reactions. The adsorption of the selenate was therefore exothermic and became weaker with increasing temperature. The bidentate inner-spheric complex was more sensitive to rises in temperature (-70 kJ/mol), compared to the outer-spheric complex (-36 kJ/mol). The latter ultimately became the dominating adsorption process at the highest temperature studied. (orig.)

Absence of zero-temperature transmission rate of a double-chain tight-binding model for DNA with random sequence of nucleotides in thermodynamic limit

International Nuclear Information System (INIS)

Xiong Gang; Wang, X.R.

2005-01-01

The zero-temperature transmission rate spectrum of a double-chain tight-binding model for real DNA is calculated. It is shown that a band of extended-like states exists only for finite chain length with strong inter-chain coupling. While the whole spectrum tends to zero in thermodynamic limit, regardless of the strength of inter-chain coupling. It is also shown that a more faithful model for real DNA with periodic sugar-phosphate chains in backbone structures can be mapped into the above simple double-chain tight-binding model. Combined with above results, the transmission rate of real DNA with long random sequence of nucleotides is expected to be poor

Zero Gravity Research Facility (Zero-G)

Data.gov (United States)

Federal Laboratory Consortium — The Zero Gravity Research Facility (Zero-G) provides a near weightless or microgravity environment for a duration of 5.18 seconds. This is accomplished by allowing...

High operating temperature interband cascade focal plane arrays

Energy Technology Data Exchange (ETDEWEB)

Tian, Z.-B.; Godoy, S. E.; Kim, H. S.; Schuler-Sandy, T.; Montoya, J. A.; Krishna, S. [Center for High Technology Materials, Department of Electrical and Computer Engineering, University of New Mexico, Albuquerque, New Mexico 87106 (United States)

2014-08-04

In this paper, we report the initial demonstration of mid-infrared interband cascade (IC) photodetector focal plane arrays with multiple-stage/junction design. The merits of IC photodetectors include low noise and efficient photocarrier extraction, even for zero-bias operation. By adopting enhanced electron barrier design and a total absorber thickness of 0.7 μm, the 5-stage IC detectors show very low dark current (1.10 × 10{sup −7} A/cm{sup 2} at −5 mV and 150 K). Even with un-optimized fabrication and standard commercial (mis-matched) read-out circuit technology, infrared images are obtained by the 320 × 256 IC focal plane array up to 180 K with f/2.3 optics. The minimum noise equivalent temperature difference of 28 mK is obtained at 120 K. These initial results indicate great potential of IC photodetectors, particularly for high operating temperature applications.

High operating temperature interband cascade focal plane arrays

International Nuclear Information System (INIS)

Tian, Z.-B.; Godoy, S. E.; Kim, H. S.; Schuler-Sandy, T.; Montoya, J. A.; Krishna, S.

2014-01-01

In this paper, we report the initial demonstration of mid-infrared interband cascade (IC) photodetector focal plane arrays with multiple-stage/junction design. The merits of IC photodetectors include low noise and efficient photocarrier extraction, even for zero-bias operation. By adopting enhanced electron barrier design and a total absorber thickness of 0.7 μm, the 5-stage IC detectors show very low dark current (1.10 × 10 −7 A/cm 2 at −5 mV and 150 K). Even with un-optimized fabrication and standard commercial (mis-matched) read-out circuit technology, infrared images are obtained by the 320 × 256 IC focal plane array up to 180 K with f/2.3 optics. The minimum noise equivalent temperature difference of 28 mK is obtained at 120 K. These initial results indicate great potential of IC photodetectors, particularly for high operating temperature applications

Creating paradigms for nearly zero energy hotels in South Europe

Directory of Open Access Journals (Sweden)

Theocharis Tsoutsos

2017-12-01

Full Text Available According to the European Directive on the Energy Performance of Buildings recast, hotels and other buildings of a certain size, frequently visited by the public, should set an example in environmental and energy performance. Moreover, being energy intensive buildings, they are at high priority for becoming nearly Zero Energy Buildings. Even though they represent a specific category, along with restaurants, till today there is a lack of credible data for this type of buildings, especially taking into account the wide range of different typologies (coastal, mountain, urban, rural or business, resort, spa/wellness, bed & breakfast. This paper presents the results of the actual energy performance of six south European countries (Greece, Croatia, France, Romania, Italy and Spain plus one north (Sweden for comparison, analyzed in the framework of the nearly Zero Energy Hotels (neZEH project. The project focused on providing technical assistance to existing pilot hotels for refurbishing into nearly Zero Energy Buildings, demonstrating the sustainability of investments towards zero energy and undertaking training and capacity building activities at regional, national and European level. The results showed that the primary energy use for the hosting functions across all sixteen pilot hotels can decrease dramatically—from an average of 277 kWh/m2/y to an average of 102 kWh/m2/y; an average reduction of 63%. At the same time, Renewable Energy Sources share for the hosting functions can be increased from an average of 18% to an average of 46%. The analysis also showed that hotel non-hosting functions, i.e., other facilities that require special indoor environmental conditions, such as spa, kitchen etc. are more critical than the hosting functions; their primary energy use can decrease from an average of 727 kWh/m2/y to an average of 374 kWh/m2/y.

Thermal expansion of NZP-family alkali-metal (Na, K) zirconium phosphates

International Nuclear Information System (INIS)

Orlova, A.I.; Kemenov, D.V.; Pet'kov, V.I.; Samojlov, S.G.; Kazantsev, G.N.

2000-01-01

By means of high-temperature X-ray diffraction one investigated into thermal expansion of alkali-zirconium phosphates crystallizing in NaZr 2 (PO 4 ) 3 structure type within 20-700 deg C temperature range. One synthesized phosphates of A x Zr 2.25-0.25x (PO 4 ) 3 type two series where A-Na (x = 0.5; 1.0; 2.0; 3.0; 4.0; 5.0) and K (x = 1.0; 3.0; 5.0). One calculated for them a and c parameters of the elementary cells and α a and α c linear expansion temperature coefficients. Anisotropy of thermal expansion the maximum one for AZr 2 (PO 4 ) 3 and Na 5 Zr(PO 4 ) 3 phosphates was determined. K 5 Zr(PO 4 ) 3 compound was characterized by the minimum thermal expansion at the near-zero anisotropy of Na 5 Zr(PO 4 ) 3 [ru

Wide temperature range (T = 295 K and 770-1305 K) study of the kinetics of the reactions HCO + NO and HCO + NO2 using frequency modulation spectroscopy.

Science.gov (United States)

Dammeier, J; Colberg, M; Friedrichs, G

2007-08-21

The rate constants for , HCO + NO --> HNO + CO, and , HCO + NO(2)--> products, have been measured at temperatures between 770 K modulation (FM) absorption spectroscopy. Kinetic simulations based on a comprehensive reaction mechanism showed that the rate constants for the title reactions could be sensitively extracted from the measured HCO profiles. The determined high temperature rate constants are k(1)(769-1307 K) = (7.1 +/- 2.7) x 10(12) cm(3) mol(-1) s(-1) and k(2)(804-1186 K) = (3.3 +/- 1.8) x 10(13) cm(3) mol(-1) s(-1). The room temperature values were found to be in very good agreement with existing literature data and show that both reactions are essentially temperature independent. The weak temperature dependence of can be explained by the interplay of a dominating direct abstraction pathway and a complex-forming mechanism. Both pathways yield the products HNO + CO. In contrast to , no evidence for a significant contribution of a direct high temperature abstraction channel was found for . Here, the observed temperature independent overall rate constant can be described by a complex-forming mechanism with several product channels. Detailed information on the strongly temperature dependent channel branching ratios is provided. Moreover, the high temperature rate constant of , OH + (CHO)(2), has been determined to be k(7) approximately 1.1 x 10(13) cm(3) mol(-1) s(-1).

The Single Transmembrane Segment of Minimal Sensor DesK Senses Temperature via a Membrane-Thickness Caliper.

Science.gov (United States)

Inda, Maria E; Oliveira, Rafael G; de Mendoza, Diego; Cybulski, Larisa E

2016-11-01

Thermosensors detect temperature changes and trigger cellular responses crucial for survival at different temperatures. The thermosensor DesK is a transmembrane (TM) histidine kinase which detects a decrease in temperature through its TM segments (TMS). Here, we address a key issue: how a physical stimulus such as temperature can be converted into a cellular response. We show that the thickness of Bacillus lipid membranes varies with temperature and that such variations can be detected by DesK with great precision. On the basis of genetic studies and measurements of in vitro activity of a DesK construct with a single TMS (minimal sensor DesK [MS-DesK]), reconstituted in liposomes, we propose an interplay mechanism directed by a conserved dyad, phenylalanine 8-lysine 10. This dyad is critical to anchor the only transmembrane segment of the MS-DesK construct to the extracellular water-lipid interphase and is required for the transmembrane segment of MS-DesK to function as a caliper for precise measurement of membrane thickness. The data suggest that positively charged lysine 10, which is located in the hydrophobic core of the membrane but is close to the water-lipid interface, pulls the transmembrane region toward the water phase to localize its charge at the interface. Nevertheless, the hydrophobic residue phenylalanine 8, located at the N-terminal extreme of the TMS, has a strong tendency to remain in the lipid phase, impairing access of lysine 10 to the water phase. The outcome of this interplay is a fine-tuned sensitivity to membrane thickness that elicits conformational changes that favor different signaling states of the protein. The ability to sense and respond to extracellular signals is essential for cell survival. One example is the cellular response to temperature variation. How do cells "sense" temperature changes? It has been proposed that the bacterial thermosensor DesK acts as a molecular caliper measuring membrane thickness variations that would occur

Structural phase transformation in K2SeO4

International Nuclear Information System (INIS)

Iizumi, M.; Axe, J.D.; Shirane, G.; Shimaoka, K.

1977-01-01

Successive phase transformations in K 2 SeO 4 at T 1 = 130 K and T/sub c/ = 93 K were studied by the neutron-scattering technique. The superlattice reflections in the intermediate phase were found to be incommensurate with the lattice periodicity. The wave vector characterizing the reflections is q/sub delta/ = (1-delta) a*/3 with delta = 0.07 at 122.5 K. The deviation delta decreases with decreasing temperature with an apparently discontinuous jump to zero at T/sub c/. Below this temperature, the crystal remains commensurate and is known to be ferroelectric. The incommensurate-commensurate transition and the simultaneous occurrence of the commensurate phase and the spontaneous polarization are discussed using a Landau-type expansion of the free energy in which a term proportional to Q 3 (q/sub delta/) P/sub z/ (q 3 /sub delta/) plays an essential role in driving the incommensurate-commensurate phase transformation and in inducing the spontaneous polarization. Here, Q (q/sub delta/) is the amplitude of the primary atomic displacements with wave vector q/sub delta/ and P/sub z/(q 3 /sub delta/) is the polarization wave with wave vector q 3 /sub delta/ = 3delta (a*/3) and becomes the macroscopic polarization below T/sub c/. Above T/sub i/, a Σ 2 optic-phonon branch along (xi,0,0) shows a striking softening and ω/sub j/(q) for q approx. (1/3,0,0) tends to zero at T/sub i/. The softening results from a temperature-dependent decrease of the interlayer forces with ranges a/2 and a (a is one unit-cell length along the a axis) in the presence of strong and persisting forces with a range 3a/2. The intensities of the soft phonon were measured about different reciprocal-lattice points and were used to determine the nature of the soft-phonon mode and suggest a coupled translation of potassium ions with rotational motion of SeO 4 groups to be the origin of the lattice instability

Sample environment for neutron scattering measurements of internal stresses in engineering materials in the temperature range of 6 K to 300 K.

Science.gov (United States)

Kirichek, O; Timms, J D; Kelleher, J F; Down, R B E; Offer, C D; Kabra, S; Zhang, S Y

2017-02-01

Internal stresses in materials have a considerable effect on material properties including strength, fracture toughness, and fatigue resistance. The ENGIN-X beamline is an engineering science facility at ISIS optimized for the measurement of strain and stress using the atomic lattice planes as a strain gauge. Nowadays, the rapidly rising interest in the mechanical properties of engineering materials at low temperatures has been stimulated by the dynamic development of the cryogenic industry and the advanced applications of the superconductor technology. Here we present the design and discuss the test results of a new cryogenic sample environment system for neutron scattering measurements of internal stresses in engineering materials under a load of up to 100 kN and in the temperature range of 6 K to 300 K. Complete cooling of the system starting from the room temperature down to the base temperature takes around 90 min. Understanding of internal stresses in engineering materials at cryogenic temperatures is vital for the modelling and designing of cutting-edge superconducting magnets and other superconductor based applications.

Understanding zero-point energy in the context of classical electromagnetism

International Nuclear Information System (INIS)

Boyer, Timothy H

2016-01-01

Today’s textbooks of electromagnetism give the particular solution to Maxwell’s equations involving the integral over the charge and current sources at retarded times. However, the texts fail to emphasise that the choice of the incoming-wave boundary conditions corresponding to solutions of the homogeneous Maxwell equations must be made based upon experiment. Here we discuss the role of these incoming-wave boundary conditions for an experimenter with a hypothetical charged harmonic oscillator as his equipment. We describe the observations of the experimenter when located near a radio station or immersed in thermal radiation at temperature T . The classical physicists at the end of the 19th century chose the incoming-wave boundary conditions for the homogeneous Maxwell equations based upon the experimental observations of Lummer and Pringsheim which measured only the thermal radiation which exceeded the random radiation surrounding their measuring equipment; the physicists concluded that they could take the homogeneous solutions to vanish at zero temperature. Today at the beginning of the 21st century, classical physicists must choose the incoming-wave boundary conditions for the homogeneous Maxell equations to correspond to the full radiation spectrum revealed by the recent Casimir force measurements which detect all the radiation surrounding conducting parallel plates, including the radiation absorbed and emitted by the plates themselves. The random classical radiation spectrum revealed by the Casimir force measurements includes electromagnetic zero-point radiation, which is missing from the spectrum measured by Lummer and Pringsheim, and which cannot be eliminated by going to zero temperature. This zero-point radiation will lead to zero-point energy for all systems which have electromagnetic interactions. Thus the choice of the incoming-wave boundary conditions on the homogeneous Maxwell equations is intimately related to the ideas of zero-point energy and

Continental-Scale Temperature Reconstructions from the PAGES 2k Network

Science.gov (United States)

Kaufman, D. S.

2012-12-01

We present a major new synthesis of seven regional temperature reconstructions to elucidate the global pattern of variations and their association with climate-forcing mechanisms over the past two millennia. To coordinate the integration of new and existing data of all proxy types, the Past Global Changes (PAGES) project developed the 2k Network. It comprises nine working groups representing eight continental-scale regions and the oceans. The PAGES 2k Consortium, authoring this paper, presently includes 79 representatives from 25 countries. For this synthesis, each of the PAGES 2k working groups identified the proxy climate records for reconstructing past temperature and associated uncertainty using the data and methodologies that they deemed most appropriate for their region. The datasets are from 973 sites where tree rings, pollen, corals, lake and marine sediment, glacier ice, speleothems, and historical documents record changes in biologically and physically mediated processes that are sensitive to temperature change, among other climatic factors. The proxy records used for this synthesis are available through the NOAA World Data Center for Paleoclimatology. On long time scales, the temperature reconstructions display similarities among regions, and a large part of this common behavior can be explained by known climate forcings. Reconstructed temperatures in all regions show an overall long-term cooling trend until around 1900 C.E., followed by strong warming during the 20th century. On the multi-decadal time scale, we assessed the variability among the temperature reconstructions using principal component (PC) analysis of the standardized decadal mean temperatures over the period of overlap among the reconstructions (1200 to 1980 C.E.). PC1 explains 35% of the total variability and is strongly correlated with temperature reconstructions from the four Northern Hemisphere regions, and with the sum of external forcings including solar, volcanic, and greenhouse

Thermodynamic constants of N-[tris(hydroxymethyl)methyl-3-amino]propanesulfonic acid (Taps) from the temperatures 278.15 K to 328.15 K

Energy Technology Data Exchange (ETDEWEB)

Roy, Rabindra N. [Walter H. Hoffman Department of Chemistry, Drury University, 900 N. Benton Avenue, Springfield, MO 65802 (United States)]. E-mail: rroy@drury.edu; Roy, Lakshmi N. [Walter H. Hoffman Department of Chemistry, Drury University, 900 N. Benton Avenue, Springfield, MO 65802 (United States); LeNoue, Sean R. [Walter H. Hoffman Department of Chemistry, Drury University, 900 N. Benton Avenue, Springfield, MO 65802 (United States); Denton, Cole E. [Walter H. Hoffman Department of Chemistry, Drury University, 900 N. Benton Avenue, Springfield, MO 65802 (United States); Simon, Ashley N. [Walter H. Hoffman Department of Chemistry, Drury University, 900 N. Benton Avenue, Springfield, MO 65802 (United States); Richards, Sarah J. [Walter H. Hoffman Department of Chemistry, Drury University, 900 N. Benton Avenue, Springfield, MO 65802 (United States); Moore, Andrew C. [Walter H. Hoffman Department of Chemistry, Drury University, 900 N. Benton Avenue, Springfield, MO 65802 (United States); Roy, Chandra N. [Walter H. Hoffman Department of Chemistry, Drury University, 900 N. Benton Avenue, Springfield, MO 65802 (United States); Redmond, R. Ryan [Walter H. Hoffman Department of Chemistry, Drury University, 900 N. Benton Avenue, Springfield, MO 65802 (United States); Bryant, Paul A. [Walter H. Hoffman Department of Chemistry, Drury University, 900 N. Benton Avenue, Springfield, MO 65802 (United States)

2006-04-15

Values of the second thermodynamic dissociation constant pK{sub 2} of N-[tris(hydroxymethyl)methyl-3-amino]propanesulfonic acid (Taps) have been determined at twelve temperatures from 278.15 K to 328.15 K including 310.15 K by measurements of the electromotive-force for cells without liquid junction of the type: Pt|H{sub 2} (g, p{sup -}bar =101.325 kPa)|Taps (m{sub 1}), NaTapsate (m{sub 2}), NaCl (m{sub 3})|AgCl|Ag, where m denotes molality. The pK{sub 2} values for the dissociation of Taps are represented by the equation: pK{sub 2}=2969.61.(K/T) - 17.05052+2.73697.ln(T/K). The values of pK{sub 2} for Taps were found to be (8.502+/-0.0007) at T=298.15 K and (8.225+/-0.0009) at T=310.15 K, respectively, indicating thereby to be useful as buffer solutions for pH control in the region 7.4 to 8.5. The thermodynamic quantities, {delta}G{sup -}bar , {delta}H{sup -}bar , {delta}S{sup -}bar , and {delta}C{sub p}{sup -}bar dissociation process of Taps have been derived from the temperature coefficients of the pK{sub 2}.

Magnetic phase diagram of MnSi near critical temperature studied by neutron small angle scattering

International Nuclear Information System (INIS)

Ishikawa, Yoshikazu; Arai, Masatoshi

1984-01-01

The magnetic phase diagram of MnSi near the critical temperature T sub(N)=29.5K has been studied by neutron small angle scattering at KENS. It has been found that the anomalous new phase predicted by various methods to exist around at 28 K and 2 kOe is the paramagnetic phase where the magnetic correlations exhibit the same characteristics as those found at 29.5 K and zero magnetic field. This phenomenon, together with the sharp decrease of the magnetic phase boundary at T sub(N) and the substantial increase of the satellite Q vector at this temperature, has been found not to be interpreted by the current theories. (author)

Experimental (155 K) and predicted (151 K) Curie temperature (Tc) of K2ZnBr4: structural confirmation of ferroelectric state below Tc

International Nuclear Information System (INIS)

Abrahams, S.C.

1994-01-01

The temperature T c at which K 2 ZnBr 4 is predicted to transform from the paraelectric to the ferroelectric phase is 151 (19) K, based on the crystal structure determinations at 291 and 144 K by Fabry, Breczewski, Zuniga and Arnaiz and the Abrahams-Kurtz-Jamieson relationship. A dielectric and heat-capacity anomaly in this material at 155 K has been reported elsewhere. The locations reported for the ZnBr 2- 4 and K + ions fulfill the requirements of mirror plane symmetry above T c ; ionic displacements along the polar direction that approach but do not exceed 0.1 A and that violate the mirror symmetry on cooling through T c form the basis of the prediction and satisfy the structural criteria for ferroelectricity in the phase below the transition. (orig.)

An additive approach to low temperature zero pressure sintering of bismuth antimony telluride thermoelectric materials

Science.gov (United States)

Catlin, Glenn C.; Tripathi, Rajesh; Nunes, Geoffrey; Lynch, Philip B.; Jones, Howard D.; Schmitt, Devin C.

2017-03-01

This paper presents an additive-based approach to the formulation of thermoelectric materials suitable for screen printing. Such printing processes are a likely route to such thermoelectric applications as micro-generators for wireless sensor networks and medical devices, but require the development of materials that can be sintered at ambient pressure and low temperatures. Using a rapid screening process, we identify the eutectic combination of antimony and tellurium as an additive for bismuth-antimony-telluride that enables good thermoelectric performance without a high pressure step. An optimized composite of 15 weight percent Sb7.5Te92.5 in Bi0.5Sb1.5Te3 is scaled up and formulated into a screen-printable paste. Samples fabricated from this paste achieve a thermoelectric figure of merit (ZT) of 0.74 using a maximum processing temperature of 748 K and a total thermal processing budget of 12 K-hours.

Temperature dependent electrical characteristics of Zn/ZnSe/n-GaAs/In structure

Science.gov (United States)

Sağlam, M.; Güzeldir, B.

2016-04-01

We have reported a study of the I-V characteristics of Zn/ZnSe/n-GaAs/In sandwich structure in a wide temperature range of 80-300 K by a step of 20 K, which are prepared by Successive Ionic Layer Adsorption and Reaction (SILAR) method. The main electrical parameters, such as ideality factor and zero-bias barrier height determined from the forward bias I-V characteristics were found strongly depend on temperature and when the increased, the n decreased with increasing temperature. The ideality factor and barrier height values as a function of the sample temperature have been attributed to the presence of the lateral inhomogeneities of the barrier height. Furthermore, the series resistance have been calculated from the I-V measurements as a function of temperature dependent.

Coupling of Rayleigh-like waves with zero-sound modes in normal 3He

International Nuclear Information System (INIS)

Bogacz, S.A.; Ketterson, J.B.

1985-01-01

The Landau kinetic equation is solved in the collisionless regime for a sample of normal 3 He excited by a surface perturbation of arbitrary ω and k. The boundary condition for the nonequilibrium particle distribution is determined for the case of specular reflection of the elementary excitations at the interface. Using the above solution, the energy flux through the boundary is obtained as a function of the surface wave velocity ω/k. The absorption spectrum and its frequency derivative are calculated numerically for typical values of temperature and pressure. The spectrum displays a sharp, resonant-like maximum concentrated at the longitudinal sound velocity and a sharp maximum of the derivative concentrated at the transverse sound velocity. The energy transfer is cut off discontinuously below the Fermi velocity. An experimental measurement of the energy transfer spectrum would permit a determination of both zero-sound velocities and the Fermi velocity with spectroscopic precision

Mechanical behaviour of substitutional body centered cubic Fe-Ti solid solutions at temperatures between 77 and 900 K; Plasticite des solutions solides cubiques centrees substitutionnelles fer-titane aux temperatures comprises entre 77 et 900 K

Energy Technology Data Exchange (ETDEWEB)

Dubots, Patrick

1976-05-11

Plastic behavior of body-centered cubic, interstitial free, Fe-Ti substitutional solid solutions has been characterised. We obtained the following results: at temperatures below 500 K, the thermal component τ* of the critical resolved shear stress τ greatly increases. Solute additions (c >0.12 wt pc) results in: softening at temperatures below 200 K, hardening at temperatures between 200 and 500 K. Results are discussed on Peierls mechanism. At temperatures below 200 K, screw dislocation motion is controlled.by the nucleation of dislocation pairs over the Peierls'hill. Substitutional solute favoring this process gives account of the softening. At temperatures above 200 K, edge dislocation motion controls the strain. The observed hardening is explained by the interaction occurring between edge-dislocations and foreign atoms. At temperatures between 500 and 800 K, a Portevin-Le Chatelier effect is observed. This effect is characterised by two types of serrations. The activation energy of the PLC effect has been determined (E = 1,4 eV). The origin of this phenomenon is the diffusion of solute towards dislocation by a vacancy-mechanism. Two maxima have been observed on the (σ{sub ε} - T) curves. These are due to superposition of overstraining (hardening) and creation of dislocations (softening). The athermal component τ{sub μ} is increased by titanium additions. This hardening has been explained by modulus and size effects. (author) [French] La caracterisation des mecanismes controlant la deformation plastique des solutions solides cubiques centrees substitutionnelles fer-titane, libres d'interstitiels pour les teneurs en solute superieures a 0,12pc pds, a donne les resultats suivants: aux temperatures inferieures a 500 K, la composante thermique τ* de la contrainte critique de cisaillement resolue τ augmente fortement. L'introduction du solute se traduit (pour c>0,12 pc pds): par un adoucissement pour θ < 200 K; par un durcissement pour 200 K< θ < 500 K. Le

Empirical temperature-dependent intermolecular potentials determined by data mining from crystal data

Science.gov (United States)

Hofmann, D. W. M.; Kuleshova, L. N.

2018-05-01

Modern force fields are accurate enough to describe thermal effects in molecular crystals. Here, we have extended our earlier approach to discrete force fields for various temperatures to a force field with a continuous function. For the parametrisation of the force field, we used data mining on experimental structures with the temperature as an additional descriptor. The obtained force field can be used to minimise energy at a finite temperature and for molecular dynamics with zero-K potentials. The applicability of the method has been demonstrated for the prediction of crystal density, temperature density gradients and transition temperature.

Magnetic-field and temperature dependence of the energy gap in InN nanobelt

Directory of Open Access Journals (Sweden)

K. Aravind

2012-03-01

Full Text Available We present tunneling measurements on an InN nanobelt which shows signatures of superconductivity. Superconducting transition takes place at temperature of 1.3K and the critical magnetic field is measured to be about 5.5kGs. The energy gap extrapolated to absolute temperature is about 110μeV. As the magnetic field is decreased to cross the critical magnetic field, the device shows a huge zero-bias magnetoresistance ratio of about 400%. This is attributed to the suppression of quasiparticle subgap tunneling in the presence of superconductivity. The measured magnetic-field and temperature dependence of the superconducting gap agree well with the reported dependences for conventional metallic superconductors.

Equation of state calculations for two-dimensional dust coulomb crystal at near zero temperature by molecular dynamics simulations

Energy Technology Data Exchange (ETDEWEB)

Djouder, M., E-mail: djouder-madjid@ummto.dz; Kermoun, F.; Mitiche, M. D.; Lamrous, O. [Laboratoire de Physique et Chimie Quantique, Université Mouloud Mammeri Tizi-Ouzou, BP 17 RP, 15000 Tizi-Ouzou (Algeria)

2016-01-15

Dust particles observed in universe as well as in laboratory and technological plasma devices are still under investigation. At low temperature, these particles are strongly negatively charged and are able to form a 2D or 3D coulomb crystal. In this work, our aim was to check the ideal gas law validity for a 2D single-layer dust crystal recently reported in the literature. For this purpose, we have simulated, using the molecular dynamics method, its thermodynamic properties for different values of dust particles number and confinement parameters. The obtained results have allowed us to invalidate the ideal gas behaviour and to propose an effective equation of state which assumes a near zero dust temperature. Furthermore, the value of the calculated sound velocity was found to be in a good agreement with experimental data published elsewhere.

Equation of state calculations for two-dimensional dust coulomb crystal at near zero temperature by molecular dynamics simulations

International Nuclear Information System (INIS)

Djouder, M.; Kermoun, F.; Mitiche, M. D.; Lamrous, O.

2016-01-01

Dust particles observed in universe as well as in laboratory and technological plasma devices are still under investigation. At low temperature, these particles are strongly negatively charged and are able to form a 2D or 3D coulomb crystal. In this work, our aim was to check the ideal gas law validity for a 2D single-layer dust crystal recently reported in the literature. For this purpose, we have simulated, using the molecular dynamics method, its thermodynamic properties for different values of dust particles number and confinement parameters. The obtained results have allowed us to invalidate the ideal gas behaviour and to propose an effective equation of state which assumes a near zero dust temperature. Furthermore, the value of the calculated sound velocity was found to be in a good agreement with experimental data published elsewhere

Bilateral Comparison Between NIM and NMC Over the Temperature Range from 83.8058 K to 692.677 K

Science.gov (United States)

Sun, Jianping; Ye, Shaochun; Kho, Haoyuan; Zhang, Jintao; Wang, Li

2015-08-01

A bilateral comparison of local realization of the International Temperature Scale of 1990 between the National Institute of Metrology (NIM) and National Metrology Centre (NMC) was carried out over the temperature range from 83.8058 K to 692.677 K. It involved six fixed points including the argon triple point, the mercury triple point, the triple point of water, the melting point of gallium, the freezing point of tin, and the freezing point of zinc. In 2009, NMC asked NIM to participate in a bilateral comparison to link the NMC results to the Consultative Committee for Thermometry Key Comparison 3 (CCT-K3) and facilitate the NMC's calibration and measurement capabilities submission. This comparison was agreed by NIM and Asia Pacific Metrology Programme in 2009, and registered in the Key Comparison Database in 2010 as CCT-K3.2. NMC supplied two fused silica sheath standard platinum resistance thermometers (SPRTs) as traveling standards. One of them was used at the Ga, Sn, and Zn fixed points, while the other one was used at the Ar and Hg fixed points. NMC measured them before and after NIM measured them. During the comparison, a criterion for the SPRT was set as the stability at the triple point of water to be less than 0.3 mK. The results for both laboratories are summarized. A proposal for linking the NMC's comparison results to CCT-K3 is presented. The difference between NMC and NIM and the difference between NMC and the CCT-K3 average reference value using NIM as a link are reported with expanded uncertainties at each measured fixed point.

Zero-One Law for Regular Languages and Semigroups with Zero

OpenAIRE

Sin'ya, Ryoma

2015-01-01

A regular language has the zero-one law if its asymptotic density converges to either zero or one. We prove that the class of all zero-one languages is closed under Boolean operations and quotients. Moreover, we prove that a regular language has the zero-one law if and only if its syntactic monoid has a zero element. Our proof gives both algebraic and automata characterisation of the zero-one law for regular languages, and it leads the following two corollaries: (i) There is an O(n log n) alg...

Densities and apparent molar volumes of aqueous LiI solutions at temperatures from (296 to 600) K and at pressures up to 30 MPa

International Nuclear Information System (INIS)

Abdulagatov, I.M.; Azizov, N.D.

2004-01-01

Densities of five aqueous LiI solutions (0.0906, 0.2832, 0.6621, 1.6046, and 3.0886) mol . kg -1 H 2 O were measured in the liquid phase with a constant-volume piezometer immersed in a precision liquid thermostat. Measurements were made along various isotherms between (296.95 and 600.25) K. The range of pressure was (0.1 to 30) MPa. The total uncertainty of density, pressure, temperature, and concentration measurements was estimated to be less than 0.06%, 0.05%, 15 mK, and 0.014%, respectively. To check and confirm the accuracy of the measurements, (p,V m ,T,x) data were taken for pure water at selected temperatures and pressures. Experimental and calculated (IAPWS formulation) densities for pure water show excellent agreement within their experimental uncertainties (average absolute deviation is 0.02%). Values of saturated densities were determined by extrapolating experimental p - ρ data to the vapour pressure at fixed temperature and composition using a linear interpolating equation. Apparent molar volumes were derived using measured values of density for solutions and pure water. The apparent molar volumes were extrapolated to zero concentration (m → 0) to yield partial molar volumes of electrolyte (LiI) at infinite dilution. The temperature, pressure, and concentration dependence of apparent and partial molar volumes was studied. The measured values of density, apparent and partial molar volume were compared with data reported in the literature by other authors. A polynomial type of equation of state for specific volume was obtained as a function of temperature, pressure, and composition by a least-squares method using the experimental data. The average absolute deviation (AAD) between measured and calculated values from this polynomial equation for density was 0.065%

Effective temperatures of late-type stars: The field giants from K0 to M6

International Nuclear Information System (INIS)

Ridgway, S.T.; Joyce, R.R.; White, N.M.; Wing, R.F.

1980-01-01

Angular diameters from lunar occultation are combined with infrared photometry to determine effective temperatures, T/sub eff/, for K0--M6 giants. The relation between T/sub eff/ and color temperature, MK spectral type, V--K color, and I (104) --L color are derived. The principal result is a general increase in T/sub eff/ for the cooler spectral types compared to previous calibrations. Throughout the temperature range studied, we obtain excellent agreement with recent model atmosphere computations

Thermal properties of Permian Basin evaporites to 493 K temperature and 30 MPa confining pressure

International Nuclear Information System (INIS)

Durham, W.B.; Heard, H.C.; Boro, C.O.; Keller, K.T.; Ralph, W.E.; Trimmer, D.A.

1987-03-01

Laboratory measurements of the thermal conductivity and diffusivity of four rock salts, two anhydrites, and two dolomites bordering Cycle 4 and Cycle 5 bedded salt formations in the Permian Basin in Deaf Smith County, Texas, were made in conditions ranging from 303 to 473 K in temperature and 0.1 to 31.0 MPa in hydrostatic confining pressure. Within the +-5% measurement resolution neither conductivity nor diffusivity showed a dependence upon pressure in any of the rocks. Conductivity and diffusivity in all rocks had a negative temperature dependence. For the Cycle 4 salt samples, conductivity fell from 5.5 to 3.75 W/m . K, and diffusivity fell from about 2.7 to 1.7 x 10 -6 m 2 /s. One Cycle 5 salt was a single crystal with anomalous results, but the other had a low conductivity with very weak temperature dependence and a high diffusivity. In the nonsalts, conductivity and diffusivity decreased 10 to 20% over the temperature range explored. In measurements of the coefficient of thermal linear expansion for Cycle 5 salt and nonsalts, the coefficient typically varied from about 12 x 10 -6 K -1 at P = 3.0 MPa to 4 x 10 -6 K -1 at P = 30 MPa for both nonsalt rocks. In anhydrite, it decreased with increasing temperature. In dolomite, the coefficient increased at roughly the same rate. Expansion of the salt ranged from 33 to 38 x 10 -6 K -1 and was independent of pressure and temperature

Reply to "On Vaporization of liquid Pb-Li eutectic alloy from 1000 K to 1200 K- A high temperature mass spectrometric study"

Science.gov (United States)

Jain, Uttam; Mukherjee, Abhishek

2018-03-01

This communication is in response to a letter to editor commenting on the authors' earlier paper "Vaporization of liquid Pb-Li eutectic alloy from 1000 K to 1200 K - A high temperature mass spectrometric study".

Processing yttrium-barium-copper oxide superconductor zero gravity using a double float zone surface

International Nuclear Information System (INIS)

Pettit, D.R.; Peterson, D.E.; Kubat-Martin, K.A.; Petrovic, J.J.; Sheinberg, H.; Coulter, Y.; Day, D.E.

1997-04-01

The effects of processing YBa 2 Cu 3 O x (Y123) superconductor in the near-zero gravity (0g) environment provided by the NASA KC-135 airplane flying on parabolic trajectories were studied. A new sheet float zone furnace, designed for this study, enabled fast temperature ramps. Up to an 18-gram sample was processed with each parabola. Samples of Y123 were processed as bulk sheets, composites containing Ag and Pd, and films deposited on single crystal Si and MgO substrates. The 0g-processed samples were multi-phase yet retained a localized Y123 stoichiometry where a single ground-based (1g) oxygen anneal at temperatures of 800 C recovered nearly 100-volume percent superconducting Y123. The 1g processed control samples remained multi-phase after the same ground-based anneal with less than 45 volume percent as superconducting Y123. The superconducting transition temperature was 91 K for both 0g and 1g processed samples. A 29 wt.% Ag/Y123 composite had a transition temperature of 93 K. Melt texturing of bulk Y123 in 0g produced aligned grains about a factor of three larger than in analogous 1g samples. Transport critical current densities were at or below 18 A/cm 2 , due to the formation of cracks caused by the rapid heating rates required by the short time at 0g. Y123 deposited on single crystal Si and MgO in 0g was 30 vol.% y123 without an anneal. A weak superconducting transition at 80 K on MgO showed that substrate interactions occurred

Bimetallic strip for low temperature use. [4-300/sup 0/K

Science.gov (United States)

Bussiee, J.F.; Welch, D.O.; Suenaga, M.

A class of mechanically pre-stressed structures is provided suitably bi-layer strips, consisting of a layer of group 5 transition metals in intimate contact with a layer of an intermetallic compound of transition metals with certain group 3A, 4A or 5A metals or metalloids such as Ga, In, Si, Ge, Sn, As or Sb. The changes of Young's modulus of these bi-layered combinations at temperatures in the region of somewhat above absolute zero provides a useful means of sensing temperature changes. Such bi-metallic strips may be used as control strips in thermostats, or in direct dial reading instruments. The structures are made by preparing a sandwich of a group 5B transition metal strip between the substantially thicker strips of an alloy between copper and a predetermined group 3A, 4A or 5A metal or metalloid, holding the three layers are heated, cooled the copper alloys and is removed. Removing one of the two formed interlayer alloys between the transition metal and the metal previously alloyed with copper remain.

The development of a cryogenic integrated system with the working temperature of 100K

Science.gov (United States)

Liu, En'guang; Wu, Yi'nong; Wang, Yueming; Wen, Jiajia; Lv, Gang; Li, Chunlai; Hou, Jia; Yuan, Liyin

2016-05-01

In the infrared system, cooling down the optic components' temperature is a better choice to decrease the background radiation and maximize the sensitivity. This paper presented a 100K cryogenic optical system, for which an integrated designation of mechanical cooler, flexible thermal link and optical bench was developed. The whole infrared optic components which were assembled in a vacuum box were cooled down to 100K by two mechanical coolers. Low thermal conductivity supports and low emissivity multi-layers were used to reduce the cryogenic optical system's heat loss. The experiment results showed that in about eight hours, the temperature of the optical components reached 100K from room temperature, and the vibration from the mechanical coolers nearly have no affection to the imaging process by using of thermal links. Some experimental results of this cryogenic system will be discussed in this paper.

Performance evaluation of a lossy transmission lines based diode detector at cryogenic temperature.

Science.gov (United States)

Villa, E; Aja, B; de la Fuente, L; Artal, E

2016-01-01

This work is focused on the design, fabrication, and performance analysis of a square-law Schottky diode detector based on lossy transmission lines working under cryogenic temperature (15 K). The design analysis of a microwave detector, based on a planar gallium-arsenide low effective Schottky barrier height diode, is reported, which is aimed for achieving large input return loss as well as flat sensitivity versus frequency. The designed circuit demonstrates good sensitivity, as well as a good return loss in a wide bandwidth at Ka-band, at both room (300 K) and cryogenic (15 K) temperatures. A good sensitivity of 1000 mV/mW and input return loss better than 12 dB have been achieved when it works as a zero-bias Schottky diode detector at room temperature, increasing the sensitivity up to a minimum of 2200 mV/mW, with the need of a DC bias current, at cryogenic temperature.

Approximating maximum weight cycle covers in directed graphs with weights zero and one

NARCIS (Netherlands)

Bläser, Markus; Manthey, Bodo

2005-01-01

A cycle cover of a graph is a spanning subgraph each node of which is part of exactly one simple cycle. A $k$-cycle cover is a cycle cover where each cycle has length at least $k$. Given a complete directed graph with edge weights zero and one, Max-$k$-DCC(0, 1) is the problem of finding a k-cycle

The Magnetisation of MnB and its Variation with Temperature

Energy Technology Data Exchange (ETDEWEB)

Lundquist, N; Myers, H P

1960-12-15

It has been shown that MnB is the only ferromagnetic phase occurring in the Mn-B system. The magnetisation per unit mass at 0 K and in infinite field strength has been found to be 163 corresponding to a Bohr magneton value 1.92 per Mn atom. The Curie temperature in zero field is 300 C. The significance of this magnetic data is discussed.

Zero Distribution of System with Unknown Random Variables Case Study: Avoiding Collision Path

Directory of Open Access Journals (Sweden)

Parman Setyamartana

2014-07-01

Full Text Available This paper presents the stochastic analysis of finding the feasible trajectories of robotics arm motion at obstacle surrounding. Unknown variables are coefficients of polynomials joint angle so that the collision-free motion is achieved. ãk is matrix consisting of these unknown feasible polynomial coefficients. The pattern of feasible polynomial in the obstacle environment shows as random. This paper proposes to model the pattern of this randomness values using random polynomial with unknown variables as coefficients. The behavior of the system will be obtained from zero distribution as the characteristic of such random polynomial. Results show that the pattern of random polynomial of avoiding collision can be constructed from zero distribution. Zero distribution is like building block of the system with obstacles as uncertainty factor. By scale factor k, which has range, the random coefficient pattern can be predicted.

Temperature dependence of the Schottky-barrier heights of n-type semiconductors in the temperature range of 7 to 300 K

International Nuclear Information System (INIS)

Chen, T.P.; Lee, T.C.; Fung, S.; Beling, C.D.

1994-01-01

In this note we present the results of the temperature dependence of the SBH in Au/n-Si, Ag/n-GaAs, and Au/n-GaAs in the temperature range of 7 to 300 K from our internal photoemission measurements. (orig.)

Density of Liquid Steel over Temperature Range of 1 803-1 873 K

Institute of Scientific and Technical Information of China (English)

XIAO Feng; FANG Liang

2004-01-01

The density of three kinds of liquid steel was measured by a modified sessile drop method over the temperature range of 1 803-1 873 K. It is found that the density of liquid steels decreases with increasing temperature and carbon content in steel. Both of the density and its absolute temperature coefficient of studied steels are smaller than the literature values of pure iron. The molar volume of the steels increases with increasing temperature.

A Two-Temperature Open-Source CFD Model for Hypersonic Reacting Flows, Part One: Zero-Dimensional Analysis

Directory of Open Access Journals (Sweden)

Vincent Casseau

2016-10-01

Full Text Available A two-temperature CFD (computational fluid dynamics solver is a prerequisite to any spacecraft re-entry numerical study that aims at producing results with a satisfactory level of accuracy within realistic timescales. In this respect, a new two-temperature CFD solver, hy2Foam, has been developed within the framework of the open-source CFD platform OpenFOAM for the prediction of hypersonic reacting flows. This solver makes the distinct juncture between the trans-rotational and multiple vibrational-electronic temperatures. hy2Foam has the capability to model vibrational-translational and vibrational-vibrational energy exchanges in an eleven-species air mixture. It makes use of either the Park TTv model or the coupled vibration-dissociation-vibration (CVDV model to handle chemistry-vibration coupling and it can simulate flows with or without electronic energy. Verification of the code for various zero-dimensional adiabatic heat baths of progressive complexity has been carried out. hy2Foam has been shown to produce results in good agreement with those given by the CFD code LeMANS (The Michigan Aerothermodynamic Navier-Stokes solver and previously published data. A comparison is also performed with the open-source DSMC (direct simulation Monte Carlo code dsmcFoam. It has been demonstrated that the use of the CVDV model and rates derived from Quantum-Kinetic theory promote a satisfactory consistency between the CFD and DSMC chemistry modules.

Accelerated test techniques for micro-circuits: Evaluation of high temperature (473 k - 573 K) accelerated life test techniques as effective microcircuit screening methods

Science.gov (United States)

Johnson, G. M.

1976-01-01

The application of high temperature accelerated test techniques was shown to be an effective method of microcircuit defect screening. Comprehensive microcircuit evaluations and a series of high temperature (473 K to 573 K) life tests demonstrated that a freak or early failure population of surface contaminated devices could be completely screened in thirty two hours of test at an ambient temperature of 523 K. Equivalent screening at 398 K, as prescribed by current Military and NASA specifications, would have required in excess of 1,500 hours of test. All testing was accomplished with a Texas Instruments' 54L10, low power triple-3 input NAND gate manufactured with a titanium- tungsten (Ti-W), Gold (Au) metallization system. A number of design and/or manufacturing anomalies were also noted with the Ti-W, Au metallization system. Further study of the exact nature and cause(s) of these anomalies is recommended prior to the use of microcircuits with Ti-W, Au metallization in long life/high reliability applications. Photomicrographs of tested circuits are included.

Lanthanum gallate substrates for epitaxial high-temperature superconducting thin films

Science.gov (United States)

Sandstrom, R. L.; Giess, E. A.; Gallagher, W. J.; Segmuller, A.; Cooper, E. I.

1988-11-01

It is demonstrated that lanthanum gallate (LaGaO3) has considerable potential as an electronic substrate material for high-temperature superconducting films. It provides a good lattice and thermal expansion match to YBa2Cu3O(7-x), can be grown in large crystal sizes, is compatible with high-temperature film processing, and has a reasonably low dielectric constant and low dielectric losses. Epitaxial YBa2Cu3O(7-x) films grown on LaGaO3 single-crystal substrates by three techniques have zero resistance between 87 and 91 K.

Temperature dependence of levitation force and its relaxation in a HTS levitation system

Energy Technology Data Exchange (ETDEWEB)

Zhou Jun; Zhang Xingyi [Key Laboratory of Mechanics on Western Disaster and Environment, Department of Mechanics and Engineering Science, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000 (China); Zhou Youhe, E-mail: zhouyh@lzu.edu.c [Key Laboratory of Mechanics on Western Disaster and Environment, Department of Mechanics and Engineering Science, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, Gansu 730000 (China)

2010-03-01

Using a modified Gifford-McMahon refrigerator to cool the cylindrical bulk YBaCuO superconductor within the region of 100-10 K, and using an updated high-temperature superconductor (HTS) maglev measurement system, the levitation force and its time relaxation at different temperatures between a YBaCuO bulk superconductor and a permanent magnet (PM) have been measured under zero-field cooling. It is found that decrease the cooling temperature of HTS can decrease the hysteresis of magnetization and increase the maximum levitation force of each hysteresis loop. For the relaxation of levitation force, if the temperature is continually lowered to 10 K after the relaxation measurement at given cooling temperature is performed for 600 s, the levitation force will continue to decrease sharply with the lowering of temperature even though it will get stable if the temperature is not lowered. Our results shown in this work are a benefit to the understanding of levitation systems.

W-Band InP Wideband MMIC LNA with 30K Noise Temperature

Science.gov (United States)

Weinreb, S.; Lai, R.; Erickson, N.; Gaier, T.; Wielgus, J.

2000-01-01

This paper describe a millimeter wave low noise amplifier with extraordinary low noise, low consumption, and wide frequency range. These results are achieved utilizing state-of-the-art InP HEMT transistors coupled with CPW circuit design. The paper describes the transistor models, modeled and measured on-wafer and in-module results at both 300K am 24K operating temperatures for many samples of the device.

Reaction rate constants of HO2 + O3 in the temperature range 233-400 K

Science.gov (United States)

Wang, Xiuyan; Suto, Masako; Lee, L. C.

1988-01-01

The reaction rate constants of HO2 + O3 were measured in the temperature range 233-400 K using a discharge flow system with photofragment emission detection. In the range 233-253 K, the constants are approximately a constant value, and then increase with increasing temperature. This result suggests that the reaction may have two different channels. An expression representing the reaction rate constants is presented.

Solvent Effects in the Electroreduction of Ferrocene at Pt in the Temperature Range 200-300 K

Science.gov (United States)

1991-03-20

been obtained at iow temperatures downto 92 K ata P ulramcroeectode(dimete, 2 pm inthree alcohol solvents, namely, methanol, ethanol , and n-propanol. In...In this aree.-doutee-eace&4 Kinetic parameters for the electrooxidation of ferrocene have been obtained at low temperatures down to 193 ’K at a Pt...with solvent nature. tnsvetsiky of~aitm Davis, CA 95616 Kinetic data obtained in mteehanol, ethanol . and I1- propanol as a function of temperature

High temperature superconducting films by rf magnetron sputtering

International Nuclear Information System (INIS)

Kadin, A.M.; Ballentine, P.H.

1989-01-01

The authors have produced sputtered films of Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O by rf magnetron sputtering from an oxide target consisting of loose reacted powder. The use of a large 8-inch stoichiometric target in the magnetron mode permits films located above the central region to be free of negative-ion resputtering effects, and hence yields reproducible, uniform stoichiometric compositions for a wide range of substrate temperatures. Superconducting YBCO films have been obtained either by sputtering at low temperatures followed by an 850 0 C oxygen anneal, or alternatively by depositing onto substrates heated to ∼600 - 650 0 C and cooling in oxygen. Films prepared by the former method on cubic zirconia substrate consist of randomly oriented crystallites with zero resistance above 83 K. Those deposited on zirconia at medium temperatures without the high-temperature anneal contain smooth partially oriented crystallites, with a slightly depressed T/sub c/ ∼75K. Finally, superconducting films have been deposited on MgO using a BiSrCaCu/sub 2/O/sub x/ powder target

Progress report on the k{sub infinity} measurements of HTGR type lattices with the oscillation technique at zero reactivity; Rapport d'advancement sur les mesures de K {sub infinite} des reseaux du type HTGR avec la technique de l'oscillateur a'reactivite' nulle

Energy Technology Data Exchange (ETDEWEB)

NONE

1971-01-15

The principles of measuring k {sub infinity} for a HTGR lattice using the oscillation technique with zero reactivity were already presented at the ''9th reactor physics meeting of countries participating in the Dragon project''. A brief summary of the essential characteristics of the experiment is followed by a status report on present work.

Soft-mode transition in the ferroelastic crystal K2Hg(CN)4

International Nuclear Information System (INIS)

Powell, B.M.; Gerlach, P.N.

1989-01-01

Inelastic neutron scattering techniques have been used to investigate the structural transition from the paraelastic to the ferroelastic phase in K 2 Hg(CN) 4 . Several low-frequency phonon branches were measured along the high-symmetry directions and found to be almost independent of temperature. However, a particular low-lying branch along [111] was found to show a strong temperature dependence. The structure factor for this mode shows it to be a longitudinal, librational mode whose eigenvector specifies antiphase rotation of adjacent rigid cyanotetrahedra. This is in agreement with the change in the crystal structure observed at the transition by diffraction measurements. The frequency of this branch at the zone- boundary L point tended to zero at ∼101 K, thus showing the paraelastic to ferroelastic transition in this cyanospinel is a soft-mode transition. (author)

Cold-hearted bats: uncoupling of heart rate and metabolism during torpor at sub-zero temperatures.

Science.gov (United States)

Currie, Shannon E; Stawski, Clare; Geiser, Fritz

2018-01-04

Many hibernating animals thermoregulate during torpor and defend their body temperature ( T b ) near 0°C by an increase in metabolic rate. Above a critical temperature ( T crit ), animals usually thermoconform. We investigated the physiological responses above and below T crit for a small tree-dwelling bat ( Chalinolobus gouldii , ∼14 g) that is often exposed to sub-zero temperatures during winter. Through simultaneous measurement of heart rate ( f H ) and oxygen consumption ( V̇ O 2 ), we show that the relationship between oxygen transport and cardiac function is substantially altered in thermoregulating torpid bats between 1 and -2°C, compared with thermoconforming torpid bats at mild ambient temperatures ( T a 5-20°C). T crit for this species was at a T a of 0.7±0.4°C, with a corresponding T b of 1.8±1.2°C. Below T crit , animals began to thermoregulate, as indicated by a considerable but disproportionate increase in both f H and V̇ O 2 The maximum increase in f H was only 4-fold greater than the average thermoconforming minimum, compared with a 46-fold increase in V̇ O 2 The differential response of f H and V̇ O 2  to low T a was reflected in a 15-fold increase in oxygen delivery per heart beat (cardiac oxygen pulse). During torpor at low T a , thermoregulating bats maintained a relatively slow f H and compensated for increased metabolic demands by significantly increasing stroke volume and tissue oxygen extraction. Our study provides new information on the relationship between metabolism and f H in an unstudied physiological state that may occur frequently in the wild and can be extremely costly for heterothermic animals. © 2018. Published by The Company of Biologists Ltd.

Thermal properties of Na2MoO4(s) and Na2Mo2O7(s) by high-temperature Calvet calorimetry in the temperature range 335 K to 760 K

International Nuclear Information System (INIS)

Iyer, V.S.; Agarwal, Renu; Roy, K.N.; Venkateswaran, R.S.; Venugopal, V.; Sood, D.D.

1990-01-01

Enthalpy increment measurements were made on Na 2 MoO 4 and Na 2 Mo 2 O 7 in the temperature range 335 K to 760 K by the drop method using a high-temperature Calvet calorimeter. The calorimeter was calibrated using an electrical method and synthetic sapphire SRM-720(Al 2 O 3 ). An on-line computer was used for acquiring and processing results from the calorimeter. The enthalpy increments for Na 2 MoO 4 and Na 2 Mo 2 O 7 were least-squares fitted to a polynomial with temperature and are given. The thermal properties of Na 2 MoO 4 and Na 2 Mo 2 O 7 were obtained using the above experimental values. These are the first experimental results on the thermal properties of these compounds. (author)

Experimental investigation of zero phase shift effects for Coriolis flowmeters due to pipe imperfections

DEFF Research Database (Denmark)

Enz, Stephanie; Thomsen, Jon Juel; Neumeyer, Stefan

2011-01-01

mass as well as temperature changes could be causes contributing to a time-varying measured zero shift, as observed with some commercial CFMs. The conducted experimental tests of the theoretically based hypotheses have shown that simple mathematical models and approximate analysis allow general......, the flexural vibrations of two bent, parallel, non-fluid-conveying pipes are studied experimentally, employing an industrial CFM. Special attention has been paid on the phase shift in the case of zero mass flow, i.e. the zero shift, caused by various imperfections to the ‘‘perfect’’ CFM, i.e. non-uniform pipe...... damping and mass, and on ambient temperature changes. Experimental observations confirm the hypothesis that asymmetry in the axial distribution of damping will induce zero shifts similar to the phase shifts due to fluid flow. Axially symmetrically distributed damping was observed to influence phase shift...

Simultaneous temperature measurement of ionospheric plasma and neutral atmosphere with K-10-11 rocket

International Nuclear Information System (INIS)

Murasato, Yukio; Kaneko, Osamu; Sasaki, Susumu; Kawashima, Nobuki; Kibune, Tadashi.

1976-01-01

Ion temperature and neutral atmospheric temperature in lower ionospheric layer were measured by the ''Shadow Method'', which has been developed and improved by the authors. The principle of the method, which utilizes the fact that the shadow due to the reduction of density of medium behind on obstacle depends upon the flow velocity and the temperature of the medium, is briefly explained together with the apparatus used for the measurement. A pair of the Langmuir probes with the interval of 44 mm was used for the measurement of ion temperature. For the measurement of the neutral atmospheric temperature, its density was measured with the ionization gauge. The measuring system was mounted on the K-10-11 rocket, and launched from KSC at 2 p.m., September 24, 1975. Although the rocket itself reached its highest altitude of 196 km, the temperature measurement was performed between the altitude of 80 km and 140 km. The measured temperatures of ions, neutral atmosphere, and electrons are presented as the functions of altitude. It is confirmed that the temperatures of ions and neutral atmosphere are lower than that of electrons in that range of altitude. (Aoki, K.)

Microwave absorption properties of flake-shaped Co particles composites at elevated temperature (293-673 K) in X band

Science.gov (United States)

Wang, Guowu; Li, Xiling; Wang, Peng; Zhang, Junming; Wang, Dian; Qiao, Liang; Wang, Tao; Li, Fashen

2018-06-01

The complex permeability and permittivity of the easy-plane anisotropic Co/polyimide composite at high temperature (293-673 K) in X band were measured. The results show that both the complex permeability and permittivity increase with the increase of temperature in the measured temperature range. The calculated absorption properties display that the intensity of the reflection loss (RL) peak first increases and then decreases with the increase of temperature, and reaches the maximum (-52 dB) at 523 K. At each temperature, the composite can achieve the RL exceeding -10 dB in the whole X band. The composite can even work stably for more than 20 min with the excellent absorption performance under 673 K. In addition, the RL performance of the composite at high temperature is better than that at room temperature.

In situ synthesis of zero-valent silver nanoparticles in polymethylmethacrylate under high temperature

International Nuclear Information System (INIS)

Xiong Yuanlu; Luo Guoqiang; Chen Cheng; Yuan Huan; Shen Qiang; Li Meijuan

2012-01-01

In this work, the silver nanoparticles were synthesized in polymethylmethacrylate (PMMA) matrix under high temperature with polyvinylpyrrolidone (PVP) as additional stabilizer and N,N-dimethylformamide (DMF) as reaction medium. The UV-vis spectroscopy and transmission electron microscopy (TEM) were adopted to investigate the growth and shape conversion of Ag nanoparticles with the lacking of additional Ag source. The results showed that the stable zero-valent Ag in PMMA was obtained successfully. Two types of Ag nanoparticles, single-crystal and twinned ones, could form in the initial period. While the twinned ones will gradually disappear along with the reaction processed, the single-crystal ones could survive and slowly grow by consuming the Ag atoms which were etched form twinned ones. The single-crystal ones will take shape conversion from sphere to nanocube with nearly the same particle size after the total disappearance of twinned ones. The size and shape of Ag nanoparticles can be well controlled by reaction time. The high viscosity PMMA matrix plays the important role of controlling the growth of the Ag nanoparticles, and the PVP takes the responsibility of the shape conversion.

Origin of the Drude peak and of zero sound in probe brane holography

Directory of Open Access Journals (Sweden)

Chi-Fang Chen

2017-11-01

Full Text Available At zero temperature, the charge current operator appears to be conserved, within linear response, in certain holographic probe brane models of strange metals. At small but finite temperature, we analytically show that the weak non-conservation of this current leads to both a collective “zero sound” mode and a Drude peak in the electrical conductivity. This simultaneously resolves two outstanding puzzles about probe brane theories. The nonlinear dynamics of the current operator itself appears qualitatively different.

Collecting the Missing Piece of the Puzzle: The Wind Temperatures of Arcturus (K2 III) and Aldeberan (K5 III)

Science.gov (United States)

Harper, Graham

2017-08-01

Unravelling the poorly understood processes that drive mass loss from red giant stars requires that we empirically constrain the intimately coupled momentum and energy balance. Hubble high spectral resolution observations of wind scattered line profiles, from neutral and singly ionized species, have provided measures of wind acceleration, turbulence, terminal speeds, and mass-loss rates. These wind properties inform us about the force-momentum balance, however, the spectra have not yielded measures of the much needed wind temperatures, which constrain the energy balance.We proposed to remedy this omission with STIS E140H observations of the Si III 1206 Ang. resonance emission line for two of the best studied red giants: Arcturus (alpha Boo: K2 III) and Aldebaran (alpha Tau: K5 III), both of which have detailed semi-empirical wind velocity models. The relative optical depths of wind scattered absorption in Si III 1206 Ang., O I 1303 Ang. triplet., C II 1335 Ang., and existing Mg II h & k and Fe II profiles give the wind temperatures through the thermally controlled ionization balance. The new temperature constraints will be used to test existing semi-empirical models by comparision with multi-frequency JVLA radio fluxes, and also to constrain the flux-tube geometry and wave energy spectrum of magnetic wave-driven winds.

Partition function zeros of the one-dimensional Potts model: the recursive method

International Nuclear Information System (INIS)

Ghulghazaryan, R G; Ananikian, N S

2003-01-01

The Yang-Lee, Fisher and Potts zeros of the one-dimensional Q-state Potts model are studied using the theory of dynamical systems. An exact recurrence relation for the partition function is derived. It is shown that zeros of the partition function may be associated with neutral fixed points of the recurrence relation. Further, a general equation for zeros of the partition function is found and a classification of the Yang-Lee, Fisher and Potts zeros is given. It is shown that the Fisher zeros in a nonzero magnetic field are located on several lines in the complex temperature plane and that the number of these lines depends on the value of the magnetic field. Analytical expressions for the densities of the Yang-Lee, Fisher and Potts zeros are derived. It is shown that densities of all types of zeros of the partition function are singular at the edge singularity points with the same critical exponent

Non-zero total correlation means non-zero quantum correlation

International Nuclear Information System (INIS)

Li, Bo; Chen, Lin; Fan, Heng

2014-01-01

We investigated the super quantum discord based on weak measurements. The super quantum discord is an extension of the standard quantum discord defined by projective measurements and also describes the quantumness of correlations. We provide some equivalent conditions for zero super quantum discord by using quantum discord, classical correlation and mutual information. In particular, we find that the super quantum discord is zero only for product states, which have zero mutual information. This result suggests that non-zero correlations can always be detected using the quantum correlation with weak measurements. As an example, we present the assisted state-discrimination method.

A simple model for correcting the zero point energy problem in classical trajectory simulations of polyatomic molecules

International Nuclear Information System (INIS)

Miller, W.H.; Hase, W.L.; Darling, C.L.

1989-01-01

A simple model is proposed for correcting problems with zero point energy in classical trajectory simulations of dynamical processes in polyatomic molecules. The ''problems'' referred to are that classical mechanics allows the vibrational energy in a mode to decrease below its quantum zero point value, and since the total energy is conserved classically this can allow too much energy to pool in other modes. The proposed model introduces hard sphere-like terms in action--angle variables that prevent the vibrational energy in any mode from falling below its zero point value. The algorithm which results is quite simple in terms of the cartesian normal modes of the system: if the energy in a mode k, say, decreases below its zero point value at time t, then at this time the momentum P k for that mode has its sign changed, and the trajectory continues. This is essentially a time reversal for mode k (only exclamation point), and it conserves the total energy of the system. One can think of the model as supplying impulsive ''quantum kicks'' to a mode whose energy attempts to fall below its zero point value, a kind of ''Planck demon'' analogous to a Brownian-like random force. The model is illustrated by application to a model of CH overtone relaxation

Determining Ms temperature on a AISI D2 cold work tool steel using magnetic Barkhausen noise

Energy Technology Data Exchange (ETDEWEB)

Huallpa, Edgar Apaza, E-mail: gared1@gmail.com [Escola Politécnica da Universidade de São Paulo, Av. Prof. Mello Moraes 2463, 05508-030 SP (Brazil); Sánchez, J. Capó, E-mail: jcapo@usp.br [Departamento de Física, Facultad de Ciencias Naturales, Universidad de Oriente, Av. Patricio Lumumba s/n 90500, Santiago de Cuba (Cuba); Padovese, L.R., E-mail: lrpadove@usp.br [Escola Politécnica da Universidade de São Paulo, Av. Prof. Mello Moraes 2463, 05508-030 SP (Brazil); Goldenstein, Hélio, E-mail: hgoldens@usp.br [Escola Politécnica da Universidade de São Paulo, Av. Prof. Mello Moraes 2463, 05508-030 SP (Brazil)

2013-11-15

Highlights: ► MBN was used to follow the martensite transformation in a tool steel. ► The results were compared with resistivity experiments. ► The Ms was estimated with Andrews equation coupled to ThermoCalc calculations. The experimental results showed good agreement. -- Abstract: The use of Magnetic Barkhausen Noise (MBN) as a experimental method for measuring the martensite start (Ms) temperature was explored, using as model system a cold-work tool steel (AISI D2) austenitized at a very high temperature (1473 K), so as to transform in sub-zero temperatures. The progress of the transformation was also followed with electrical resistance measurements, optical microscopy and scanning electron microscopy. Both MBN and resistivity measurements showed a change near 230 K during cooling, corresponding to the Ms temperature, as compared with 245 K, estimated with Andrews empirical equation applied to the austenite composition calculated using ThermoCalc.

Behaviour of polar crystals at low temperatures

International Nuclear Information System (INIS)

Drozhdin, S.N.; Novik, V.K.; Gavrilova, N.D.; Koptsik, V.A.; Popova, T.V.

1975-01-01

Temperature dependencies of pyrocoefficient for a wide class of various pyroactive crystals in the temperature range from 4,2 to 300 deg K were investigated. The problems to be solved were: to confirm a conclusion on the pyrocoefficient γsup(sigma) tending to zero at T → 0; to compare experimental data with conclusions of existing theories; to reveal specific features in the behaviour of both linear pyroelectrics and segnetoelectrics at low temperatures. The behaviour of the total pyrocoefficient for all crystals obeys the regularity γsup(sigma) → 0 at T → O. In the range of low temperatures the pyrocoefficient varies by the power law: γsup(sigma) approximately Tsup(α). For the majority of crystals studied α is close to 3. CdS, BeO, ZiNbO 3 and other crystals were studied

Lee-Yang zeroes and logarithmic corrections in the Φ44 theory

International Nuclear Information System (INIS)

Kenna, R.; Lang, C.B.

1993-01-01

The leading mean-field critical behaviour of φ 4 4 -theory is modified by multiplicative logarithmic corrections. We analyse these corrections both analytically and numerically. In particular we present a finite-size scaling theory for the Lee-Yang zeroes and temperature zeroes, both of which exhibit logarithmic corrections. On lattices from size 8 4 to 24 4 , Monte-Carlo cluster methods and multi-histogram techniques are used to determine the partition function zeroes closest to the critical point. Finite-size scaling behaviour is verified and the logarithmic corrections are found to be in good agreement with our analytical predictions. (orig.)

Experimental study of the density and viscosity of polyethylene glycols and their mixtures at temperatures from 293 K to 473 K and at atmospheric pressure

International Nuclear Information System (INIS)

Sagdeev, D.I.; Fomina, M.G.; Mukhamedzyanov, G.Kh.; Abdulagatov, I.M.

2011-01-01

Highlights: → Viscosity and density of polyethylene glycols. → Combined experimental apparatus for density and viscosity measurements. → Vogel-Tamman-Fulcher model for viscosity. - Abstract: A new apparatus to measure simultaneously the density and viscosity of liquids has been designed and constructed based on the hydrostatic weighing and falling-body principles. The density and viscosity of monoethylene glycol (MEG), diethylene glycol (DEG), and triethylene glycol (TEG) and their binary, (50%MEG + 50%DEG), (50%MEG + 50%TEG), (50%DEG + 50%TEG), and ternary (33.33%MEG + 33.33%DEG + 33.34%TEG) mixtures have been measured over the temperature range from 293 K to 473 K and at atmospheric pressure. The expanded uncertainty of the density, pressure, temperature, and viscosity measurements at the 95% confidence level with a coverage factor of k = 2 is estimated to be 0.15% to 0.30%, 0.05%, 0.06 K, and 1.5% to 2.0% (depending on temperature and pressure ranges), respectively. The theoretically based Arrhenius-Andrade and Vogel-Tamman-Fulcher type equations were used to describe the temperature dependence of measured viscosities for pure polyethylene glycols and their mixtures.

Test results of full-scale high temperature superconductors cable models destined for a 36 kV, 2 kA(rms) utility demonstration

DEFF Research Database (Denmark)

Daumling, M.; Rasmussen, C.N.; Hansen, F.

2001-01-01

Power cable systems using high temperature superconductors (HTS) are nearing technical feasibility. This presentation summarises the advancements and status of a project aimed at demonstrating a 36 kV, 2 kA(rms) AC cable system by installing a 30 m long full-scale functional model in a power...

Strong Temperature Dependence in the Reactivity of H ₂ on RuO ₂ (110)

Energy Technology Data Exchange (ETDEWEB)

Henderson, Michael A.; Dahal, Arjun; Dohnálek, Zdenek; Lyubinetsky, Igor

2016-08-04

The ability of hydrogen to facilitate many types of heterogeneous catalysis starts with its adsorption. As such, understanding the temperature-dependence sticking of H2 is critical toward controlling and optimizing catalytic conditions in those cases where adsorption is rate-limiting. In this work, we examine the temperature-dependent sticking of H2/D2 to the clean RuO2(110) surface using the King & Wells molecular beam approach, temperature programmed desorption (TPD) and scanning tunneling microscopy (STM). We show that the sticking probability (molecular or dissociative) of H2/D2 on this surface is highly temperature-dependent, decreasing from ~0.4-0.5 below 25 K to effectively zero above 200 K. Both STM and TPD reveal that OH/OD formation is severely limited for adsorption temperatures above ~150 K. Previous literature reports of extensive surface hydroxylation from H2/D2 exposures at room temperature were most likely the result of inadvertent contamination brought about from dosing by chamber backfilling.

Temperature Dependence and Magnetic Field Dependence of Quantum Point Contacts in Si-Inversion Layers

NARCIS (Netherlands)

Wang, S.L.; Son, P.C. van; Wees, B.J. van; Klapwijk, T.M.

1992-01-01

The conductance of ballistic point contacts in high-mobility Si-inversion layers has been studied at several temperatures between 75 and 600 mK both without and in a magnetic field (up to 12T). When the width of constriction is varied in zero magnetic field, step-like features at multiples of 4e2/h

A comparison of zero-order, first-order, and Monod biotransformation models

International Nuclear Information System (INIS)

Bekins, B.A.; Warren, E.; Godsy, E.M.

1998-01-01

Under some conditions, a first-order kinetic model is a poor representation of biodegradation in contaminated aquifers. Although it is well known that the assumption of first-order kinetics is valid only when substrate concentration, S, is much less than the half-saturation constant, K S , this assumption is often made without verification of this condition. The authors present a formal error analysis showing that the relative error in the first-order approximation is S/K S and in the zero-order approximation the error is K S /S. They then examine the problems that arise when the first-order approximation is used outside the range for which it is valid. A series of numerical simulations comparing results of first- and zero-order rate approximations to Monod kinetics for a real data set illustrates that if concentrations observed in the field are higher than K S , it may be better to model degradation using a zero-order rate expression. Compared with Monod kinetics, extrapolation of a first-order rate to lower concentrations under-predicts the biotransformation potential, while extrapolation to higher concentrations may grossly over-predict the transformation rate. A summary of solubilities and Monod parameters for aerobic benzene, toluene, and xylene (BTX) degradation shows that the a priori assumption of first-order degradation kinetics at sites contaminated with these compounds is not valid. In particular, out of six published values of K S for toluene, only one is greater than 2 mg/L, indicating that when toluene is present in concentrations greater than about a part per million, the assumption of first-order kinetics may be invalid. Finally, the authors apply an existing analytical solution for steady-state one-dimensional advective transport with Monod degradation kinetics to a field data set

A temperature dependent tunneling study of the spin density wave gap in EuFe2As2 single crystals.

Science.gov (United States)

Dutta, Anirban; Anupam; Hossain, Z; Gupta, Anjan K

2013-09-18

We report temperature dependent scanning tunneling microscopy and spectroscopy measurements on single crystals of EuFe2As2 in the 15-292 K temperature range. The in situ cleaved crystals show atomic terraces with homogeneous tunnel spectra that correlate well with the spin density wave (SDW) transition at a temperature, TSDW ≈ 186 K. Above TSDW the local tunnel spectra show a small depression in the density of states (DOS) near the Fermi energy (EF). The gap becomes more pronounced upon entering the SDW state with a gap value ∼90 meV at 15 K. However, the zero bias conductance remains finite down to 15 K indicating a finite DOS at the EF in the SDW phase. Furthermore, no noticeable change is observed in the DOS at the antiferromagnetic ordering transition of Eu(2+) moments at 19 K.

Phase diagram of Ti-B-C system in the temperature range of 300-3500 K

International Nuclear Information System (INIS)

Gusev, A.I.

1996-01-01

Calculation of phase equilibrium in the ternary system Ti-B-C in the areas of the TiC y -TiB 2 and B 4 C y -TiB 2 cross sections as well as partial construction of three-dimensional (spatial)diagram of the Ti-B-C system within the temperature range of 300-3500 K is carried out. The form of the isothermal cross section of the ternary system remains almost unchanged up to 1900 K. The most essential change is related to disordering of the low-temperature ordered phases Ti 2 C, Ti 3 C and Ti 6 C 5 of the titanium carbide at T > 950 K [ru

On the assumption of vanishing temperature fluctuations at the wall for heat transfer modeling

Science.gov (United States)

Sommer, T. P.; So, R. M. C.; Zhang, H. S.

1993-01-01

Boundary conditions for fluctuating wall temperature are required for near-wall heat transfer modeling. However, their correct specifications for arbitrary thermal boundary conditions are not clear. The conventional approach is to assume zero fluctuating wall temperature or zero gradient for the temperature variance at the wall. These are idealized specifications and the latter condition could lead to an ill posed problem for fully-developed pipe and channel flows. In this paper, the validity and extent of the zero fluctuating wall temperature condition for heat transfer calculations is examined. The approach taken is to assume a Taylor expansion in the wall normal coordinate for the fluctuating temperature that is general enough to account for both zero and non-zero value at the wall. Turbulent conductivity is calculated from the temperature variance and its dissipation rate. Heat transfer calculations assuming both zero and non-zero fluctuating wall temperature reveal that the zero fluctuating wall temperature assumption is in general valid. The effects of non-zero fluctuating wall temperature are limited only to a very small region near the wall.

Modern high-temperature superconductivity

International Nuclear Information System (INIS)

Ching Wu Chu

1988-01-01

Ever since the discovery of superconductivity in 1911, its unusual scientific challenge and great technological potential have been recognized. For the past three-quarters of a century, superconductivity has done well on the science front. This is because sueprconductivity is interesting not only just in its own right but also in its ability to act as a probe to many exciting nonsuperconducting phenomena. For instance, it has continued to provide bases for vigorous activities in condensed matter science. Among the more recent examples are heavy-fermion systems and organic superconductors. During this same period of time, superconductivity has also performed admirably in the applied area. Many ideas have been conceived and tested, making use of the unique characteristics of superconductivity - zero resistivity, quantum interference phenomena, and the Meissner effect. In fact, it was not until late January 1987 that it became possible to achieve superconductivity with the mere use of liquid nitrogen - which is plentiful, cheap, efficient, and easy to handle - following the discovery of supercondictivity above 90 K in Y-Ba-Cu-O, the first genuine quaternary superconductor. Superconductivity above 90 K poses scientific and technological challenges not previously encountered: no existing theories can adequately describe superconductivity above 40 K and no known techniques can economically process the materials for full-scale applications. In this paper, therefore, the author recalls a few events leading to the discovery of the new class of quaternary compounds with a superconducting transition temperature T c in the 90 K range, describes the current experimental status of high-temperature superconductivity and, finally, discusses the prospect of very-high-temperature superconductivity, i.e., with a T c substantially higher than 100 K. 97 refs., 7 figs

Zero-phonon line and fine structure of the yellow luminescence band in GaN

Science.gov (United States)

Reshchikov, M. A.; McNamara, J. D.; Zhang, F.; Monavarian, M.; Usikov, A.; Helava, H.; Makarov, Yu.; Morkoç, H.

2016-07-01

The yellow luminescence band was studied in undoped and Si-doped GaN samples by steady-state and time-resolved photoluminescence. At low temperature (18 K), the zero-phonon line (ZPL) for the yellow band is observed at 2.57 eV and attributed to electron transitions from a shallow donor to a deep-level defect. At higher temperatures, the ZPL at 2.59 eV emerges, which is attributed to electron transitions from the conduction band to the same defect. In addition to the ZPL, a set of phonon replicas is observed, which is caused by the emission of phonons with energies of 39.5 meV and 91.5 meV. The defect is called the YL1 center. The possible identity of the YL1 center is discussed. The results indicate that the same defect is responsible for the strong YL1 band in undoped and Si-doped GaN samples.

Blast-cooling of beef-in-sauce catering meals: numerical results based on a dynamic zero-order model

Directory of Open Access Journals (Sweden)

Jose A. Rabi

2014-10-01

Full Text Available Beef-in-sauce catering meals under blast-cooling have been investigated in a research project which aims at quantitative HACCP (hazard analysis critical control point. In view of its prospective coupling to a predictive microbiology model proposed in the project, zero-order spatial dependence has proved to suitably predict meal temperatures in response to temperature variations in the cooling air. This approach has modelled heat transfer rates via the a priori unknown convective coefficient hc which is allowed to vary due to uncertainty and variability in the actual modus operandi of the chosen case study hospital kitchen. Implemented in MS Excel®, the numerical procedure has successfully combined the 4th order Runge-Kutta method, to solve the governing equation, with non-linear optimization, via the built-in Solver, to determine the coefficient hc. In this work, the coefficient hc was assessed for 119 distinct recently-cooked meal samples whose temperature-time profiles were recorded in situ after 17 technical visits to the hospital kitchen over a year. The average value and standard deviation results were hc = 12.0 ± 4.1 W m-2 K-1, whilst the lowest values (associated with the worst cooling scenarios were about hc » 6.0 W m-2 K-1.

PdMn and PdFe: New Materials for Temperature Measurement Near 2K

International Nuclear Information System (INIS)

Adriaans, M.J.; Aselage, T.L.; Day, P.K.; Duncan, R.V.; Klemme, B.J.; Sergatskov, D.A.

1999-01-01

Interest in the critical dynamics of superfluid 4 He in microgravity conditions has motivated the development of new high resolution thermometry technol- ogy for use in space experiments near 2K. The current material commonly used as the temperature sensing element for high resolution thermometers (HRTs) is copper ammonium bromide [Cu(NH 4 ) 2 Br 4 2H 2 0) or ''CAB'', which undergoes a ferromagnetic phase transition at 1.8K1. HRTs made from CAB have demonstrated low drift ( -13 K/s

Phase transitions in the hard-core Bose-Fermi-Hubbard model at non-zero temperatures in the heavy-fermion limit

Energy Technology Data Exchange (ETDEWEB)

Stasyuk, I.V.; Krasnov, V.O., E-mail: krasnoff@icmp.lviv.ua

2017-04-15

Phase transitions at non-zero temperatures in ultracold Bose- and Fermi-particles mixture in optical lattices using the Bose-Fermi-Hubbard model in the mean field and hard-core boson approximations are investigated. The case of infinitely small fermion transfer and the repulsive on-site boson-fermion interaction is considered. The possibility of change of order (from the 2nd to the 1st one) of the phase transition to the superfluid phase in the regime of fixed values of the chemical potentials of Bose- and Fermi-particles is established. The relevant phase diagrams determining the conditions at which such a change takes place, are built.

Lanthanum gallate substrates for epitaxial high-temperature superconducting thin films

International Nuclear Information System (INIS)

Sandstrom, R.L.; Giess, E.A.; Gallagher, W.J.; Segmueller, A.; Cooper, E.I.; Chisholm, M.F.; Gupta, A.; Shinde, S.; Laibowitz, R.B.

1988-01-01

We demonstrate that lanthanum gallate (LaGaO 3 ) has considerable potential as an electronic substrate material for high-temperature superconducting films. It provides a good lattice and thermal expansion match to YBa 2 Cu 3 O/sub 7-//sub x/, can be grown in large crystal sizes, is compatible with high-temperature film processing, and has a reasonably low dielectric constant (ε≅25) and low dielectric losses. Epitaxial YBa 2 Cu 3 O/sub 7-//sub x/ films grown on LaGaO 3 single-crystal substrates by three techniques have zero resistance between 87 and 91 K

Describing gluons at zero and finite temperature

International Nuclear Information System (INIS)

Maas, A.

2010-01-01

Any description of gluons requires a well-defined gauge. This is complicated non-perturbatively by Gribov copies. A possible method-independent gauge definition to resolve this problem is presented and afterwards used to study the properties of gluons at any temperature. It is found that only chromo-electric properties reflect the phase transition. From these the gauge-invariant phase transition temperature is determined for SU(2) and SU(3) Yang-Mills theory independently. (author)

Dislocation mechanisms for plastic flow of nickel in the temperature range 4.2-1200K

International Nuclear Information System (INIS)

Sastry, D.H.; Tangri, K.

1975-01-01

The temperature ranges of thermal and athermal deformation behaviour of nickel are identified by employing the temperature-dependence of flow-stress and strain-rate cycling data. The results are used to present a unified view of dislocation mechanisms of glide encompassing the two thermally activated and the intermediate athermal regimes of plastic flow. In the low-temperature thermally activated region (<250K) the strain rate is found to be controlled by the repulsive intersection of glide and forest dislocations, in accordance with current ideas. The athermal stress in this region can be attributed mainly to the presence of strong attractive junctions which are overcome by means of Orowan bowing, a small contribution also coming from the elastic interactions between dislocations. The values of activation area and activation energy obtained in the high-temperature region (<750K) negate the operation of a diffusion-controlled mechanism. Instead, the data support a thermal activation model involving unzipping of the attractive junctions. The internal (long-range) stress contribution here results solely from the elastic interactions between dislocations. This view concerning the high-temperature plastic flow is further supported by the observation that the Cottrell-Stokes law is obeyed over large strains in the range 750-1200K. (author)

Revisiting the definition of the electronic chemical potential, chemical hardness, and softness at finite temperatures

International Nuclear Information System (INIS)

Franco-Pérez, Marco; Gázquez, José L.; Ayers, Paul W.; Vela, Alberto

2015-01-01

We extend the definition of the electronic chemical potential (μ e ) and chemical hardness (η e ) to finite temperatures by considering a reactive chemical species as a true open system to the exchange of electrons, working exclusively within the framework of the grand canonical ensemble. As in the zero temperature derivation of these descriptors, the response of a chemical reagent to electron-transfer is determined by the response of the (average) electronic energy of the system, and not by intrinsic thermodynamic properties like the chemical potential of the electron-reservoir which is, in general, different from the electronic chemical potential, μ e . Although the dependence of the electronic energy on electron number qualitatively resembles the piecewise-continuous straight-line profile for low electronic temperatures (up to ca. 5000 K), the introduction of the temperature as a free variable smoothens this profile, so that derivatives (of all orders) of the average electronic energy with respect to the average electron number exist and can be evaluated analytically. Assuming a three-state ensemble, well-known results for the electronic chemical potential at negative (−I), positive (−A), and zero values of the fractional charge (−(I + A)/2) are recovered. Similarly, in the zero temperature limit, the chemical hardness is formally expressed as a Dirac delta function in the particle number and satisfies the well-known reciprocity relation with the global softness

Evaluation of water cooled supersonic temperature and pressure probes for application to 1366 K flows

Science.gov (United States)

Lagen, Nicholas; Seiner, John M.

1990-01-01

Water cooled supersonic probes are developed to investigate total pressure, static pressure, and total temperature in high-temperature jet plumes and thereby determine the mean flow properties. Two probe concepts, designed for operation at up to 1366 K in a Mach 2 flow, are tested on a water cooled nozzle. The two probe designs - the unsymmetric four-tube cooling configuration and the symmetric annular cooling design - take measurements at 755, 1089, and 1366 K of the three parameters. The cooled total and static pressure readings are found to agree with previous test results with uncooled configurations. The total-temperature probe, however, is affected by the introduction of water coolant, and effect which is explained by the increased heat transfer across the thermocouple-bead surface. Further investigation of the effect of coolant on the temperature probe is proposed to mitigate the effect and calculate more accurate temperatures in jet plumes.

Low-temperature, low-loss zero level packaging techniques for RF applications by using a photopatternable dry film

International Nuclear Information System (INIS)

Kim, J; Seok, S; Rolland, N; Rolland, P-A

2012-01-01

This paper presents a low-temperature zero-level packaging technique using a dry film type of PerMX polymer for RF devices. Silicon cap packaging with PerMX sealing ring and PerMX cap packaging through multilayer lamination have been implemented. All of the fabrication process has been performed at temperature less than 150 °C. The influence of each packaging cap on the packaged coplanar waveguide was first investigated using the HFSS electromagnetic simulation. The RF measurement results showed that both packaging caps did not have significant influence on the performance of transmission lines. The insertion loss changes before and after packaging were almost negligible up to 30 GHz, and the return losses were better than 20 dB. Also, the deformation of PerMX structures concerning the packaging processes has been studied. For silicon capping, the volumetric compression of PerMX sealing ring by the bonding process has been observed. For PerMX cap packaging, the deflection of the polymer cap has been investigated as a function of sealing ring width for the different cap size. Measured results had good agreement with the ANSYS simulated ones. (paper)

Thermodynamic properties of deep eutectic solvent and ionic liquid mixtures at temperatures from 293.15 K to 343.15 K

Science.gov (United States)

Achsah, R. S.; Shyam, S.; Mayuri, N.; Anantharaj, R.

2018-04-01

Deep eutectic solvents (DES) and ionic liquids (ILs) have their applications in various fields of research and in industries due to their attractive physiochemical properties. In this study, the combined thermodynamic properties of DES (choline chloride-glycerol) + IL1 (1-butyl-3-methylimiazolium acetate) and DES(choline chloride-glycerol) + IL2 (1-ethyl-3-methylimadzolium ethyl sulphate) have been studied. The thermodynamic properties such as excess molar volume, partial molar volume, excess partial molar volume and apparent molar volume were calculated for different mole fractions ranging from 0 to 1 and varying temperatures from 293.15 K to 343.15 K. In order to know the solvent properties of DESs and ILs mixtures at different temperatures and their molecular interactions to enhance the solvent performance and process efficiency at fixed composition and temperature the thermodynamic properties were analyzed.

Title: Elucidation of Environmental Fate of Artificial Sweeteners (Aspartame, Acesulfame K and Saccharin) by Determining Bimolecular Rate Constants with Hydroxyl Radical at Various pH and Temperature Conditions and Possible Reaction By-Products

Science.gov (United States)

Teraji, T.; Arakaki, T.; Suzuka, T.

2012-12-01

Use of artificial sweeteners in beverages and food has been rapidly increasing because of their non-calorie nature. In Japan, aspartame, acesulfame K and sucralose are among the most widely used artificial sweeteners. Because the artificial sweeteners are not metabolized in human bodies, they are directly excreted into the environment without chemical transformations. We initiated a study to better understand the fate of artificial sweeteners in the marine environment. The hydroxyl radical (OH), the most potent reactive oxygen species, reacts with various compounds and determines the environmental oxidation capacity and the life-time of many compounds. The steady-state OH concentration and the reaction rate constants between the compound and OH are used to estimate the life-time of the compound. In this study, we determine the bimolecular rate constants between aspartame, acefulfame K and saccharin and OH at various pH and temperature conditions using a competition kinetics technique. We use hydrogen peroxide as a photochemical source of OH. Bimolecular rate constant we obtained so far for aspartame was (2.6±1.2)×109 M-1 s-1 at pH = 3.0 and (4.9±2.3)×109 M-1 s-1 at pH = 5.5. Little effect was seen by changing the temperatures between 15 and 40 oC. Activation energy (Ea) was calculated to be -1.0 kJ mol-1 at pH = 3.0, +8.5 kJ mol-1 at pH = 5.5, which could be regarded as zero. We will report bimolecular rate constants at different pHs and temperatures for acesulfame K and saccharin, as well. Possible reaction by-products for aspartame will be also reported. We will further discuss the fate of aspartame in the coastal environment.

Laser parameters of a Fe : ZnSe crystal in the 85-255-K temperature range

NARCIS (Netherlands)

Voronov, AA; Kozlovskii, [No Value; Korostelin, YV; Podmar'kov, YP; Frolov, MP

The temperature dependence of the efficiency of a laser based on a Fe:ZnSe crystal grown from the vapour phase by the free-growth method is studied in the 85-255-K temperature range. As the temperature was increased, the slope efficiency of the laser with respect to absorbed energy decreased from

Low-temperature synthesis of CuFeO{sub 2} (delafossite) at 70 °C: A new process solely by precipitation and ageing

Energy Technology Data Exchange (ETDEWEB)

John, Melanie, E-mail: melanie.john@min.uni-muenchen.de [Section Mineralogy, Petrology & Geochemistry, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 Munich (Germany); Heuss-Aßbichler, Soraya [Section Mineralogy, Petrology & Geochemistry, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 Munich (Germany); Park, So-Hyun [Section Crystallography, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 Munich (Germany); Ullrich, Aladin [Experimental Physics II, University of Augsburg, Universitätsstr. 1, 86159 Augsburg (Germany); Benka, Georg [Physics Department, Technical University Munich, James-Franck-Straße 1, 85748 Garching (Germany); Petersen, Nikolai [Section Geophysics, Department of Earth and Environmental Sciences, Ludwig-Maximilians-Universität München, Theresienstr. 41, 80333 Munich (Germany); Rettenwander, Daniel [Department of Materials Research & Physics, University of Salzburg, Hellbrunnerstrasse 34, 5020 Salzburg (Austria); Horn, Siegfried R. [Experimental Physics II, University of Augsburg, Universitätsstr. 1, 86159 Augsburg (Germany)

2016-01-15

This study presents a new low temperature synthesis method to obtain pure delafossite (Cu{sup 1+}Fe{sup 3+}O{sub 2}) at a temperature of 70 °C within 24 h. For the first time delafossite is synthesized solely by precipitation and subsequent ageing process and without usage of any additives controlling the oxidation state of copper. The synthesized material, called LT-delafossite, consists of pure Cu{sup 1+}Fe{sup 3+}O{sub 2} exclusive of any side products. Rietveld analysis confirms the presence of both 3R (space group (SG): R-3m) and 2H (SG: P6{sub 3}/mmc) polytypes in LT-delafossite. Electron microscopy images show nanometer-sized hexagonal plates with a diameter <500 nm and a thickness of <30 nm. Measurements of the magnetic susceptibility from 2 K to 350 K in zero-field show one peak ∼18.5 K, which is attributed to an AFM phase transition. Zero-field-cooled magnetization data between −14 T and +14 T at 2 K revealed an s-shape form around the origin having no remanent magnetization. - Highlights: • New process: low temperature synthesis of pure CuFeO{sub 2} nanoparticles. • Synthesis at 70 °C within 24 h solely by precipitation and ageing. • Nanoparticle characterization by XRD, FTIR, SEM, ICP–OES, TEM and Mößbauer. • Special magnetic properties of nano-sized CuFeO{sub 2} synthesized at low temperatures.

Magnetic susceptibility of scandium-hydrogen and lutetium-hydrogen solid-solution alloys from 2 to 3000K

International Nuclear Information System (INIS)

Stierman, R.J.

1982-12-01

Results for pure Sc show that the maximum and minimum in the susceptibility discovered earlier are enhanced as the impurity level of iron in scandium decreases. The Stoner enhancement factor, calculated from low-temperature heat capacity data, susceptibility data, and band-structure calculations show Sc to be a strongly enhanced paramagnet. Below 2 0 K, the magnetic anisotropy between the hard and easy directions of scandium decreases linearly with decreasing temperature, tending toward zero at 0 K. The large increase in the susceptibility of Sc at lower temperatures indicates magnetic ordering. Pure Lu and Lu-H alloys showed an anisotropy in susceptibility vs orientation; thus the samples were not random polycrystalline samples. Pure Lu shows the shallow maximum and minimum, but the increase in susceptibility at low temperatures is larger than previously observed. The susceptibility-composition dependence of the Lu-H alloys also did not match other data. The susceptibility-composition dependence does not match the composition dependence of the electronic specific heat constant below 150 K, showing the electronic specific heat is being affected by terms other than phonon-electron and pure electron-electron interactions

Demonstration of the improved PID method for the accurate temperature control of ADRs

International Nuclear Information System (INIS)

Shinozaki, K.; Hoshino, A.; Ishisaki, Y.; Mihara, T.

2006-01-01

Microcalorimeters require extreme stability (-bar 10μK) of thermal bath at low temperature (∼100mK). We have developed a portable adiabatic demagnetization refrigerator (ADR) system for ground experiments with TES microcalorimeters, in which we observed residual temperature between aimed and measured values when magnet current was controlled with the standard Proportional, Integral, and Derivative control (PID) method. The difference increases in time as the magnet current decreases. This phenomenon can be explained by the theory of the magnetic cooling, and we have introduced a new functional parameter to improve the PID method. With this improvement, long-term stability of the ADR temperature about 10μK rms is obtained up to the period of ∼15ks down to almost zero magnet current. We briefly describe our ADR system and principle of the improved PID method, showing the temperature control result. It is demonstrated that the controlled time of the aimed temperature can be extended by about 30% longer than the standard PID method in our system. The improved PID method is considered to be of great advantage especially in the range of small magnet current

Temperature effect on the magnetic property and ferroelectricity in hexaferrite SrFe{sub 12}O{sub 19}

Energy Technology Data Exchange (ETDEWEB)

Qiang, Gang; Lu, Xiaowen; Cui, Xiaopeng; Deng, Dongmei; Kang, Baojuan; Cao, Shixun; Zhang, Jincang [Shanghai University, Materials Genome Institute and Department of Physics, Shanghai (China); Jin, Yuan [Shanghai University, Materials Genome Institute and Department of Physics, Shanghai (China); Hengdain Group DMEGC Magnetics Co.LTD., Hengdian (China); Yang, Wuguo [Hengdain Group DMEGC Magnetics Co.LTD., Hengdian (China)

2016-07-15

We studied the temperature effect on magnetic and electrical properties in bulk SrFe{sub 12}O{sub 19} prepared by conventional ceramic technique. The jumping behavior of magnetization has been observed under the zero-field-cooling mode, but disappeared under the field-cooled cooling mode. The spin moment of iron ions reorients below 50 K leading to the magnetic structure changes. Magnetic parameters, saturation magnetization (Ms) and coercivity field (Hc), show opposite tendency with temperature throughout the measuring range, which is mainly ascribed to the Fe{sup 3+} ions situated at 4f{sub 2} and 2b sites. The curves of electrical polarization P vs temperature T under different external magnetic field indicate the existence of ferroelectricity and magnetoelectric coupling effect at low temperature, and the transition temperature T{sub P} is about 120 K. (orig.)

Measurement of the elastic modulus of Kapton perpendicular to the plane of the film at room and cryogenic temperatures

International Nuclear Information System (INIS)

Davidson, M.; Bastian, S.; Markley, F.

1992-04-01

Understanding the short term elastic properties, (i.e. the instantaneous modulus) of Kapton is essential in determining the loss of prestress during storage and operation of SSC dipole magnets. The magnet prestress contributes directly to the coil response to the Lorentz forces during ramping. The instantaneous modulus is important in extrapolating short term stress relaxation data to longer times. Most theoretical fits assume a time independent component and a time dependent component. The former may be represented by the Kapton modulus near zero K where all relaxation processes have been ''frozen'' out. Modulus measurements at 77K and 4.2K may point to a correct value for the near zero K modulus. Three companion papers presented at this conference will be: ''Stress Relaxation in SSC 50 mm Dipole Coils'' ''Temperature Dependence of the Viscoelastic Properties of SSC Coil Insulation (Kapton)'' ''Theoretical Methods for Creep and Stress Relaxation Studies of SSC Coil.''

Interconnection between zero resistance and magnetic irreversibility temperatures in the hole doped Y0.9Ca0.1Ba2Cu3O7-δ single crystal

International Nuclear Information System (INIS)

Macedo, D G; Vieira, V N; Dias, F T; Silva, D L da; Jaeckel, S; Pureur, P; Schaf, J

2014-01-01

We report on ac magnetoresistance, R(T,H) and ZFC [M ZFC (T)] and FCC [M FCC (T)] dc magnetizations measurements of the a hole doped Y 0.9 Ca 0.1 Ba 2 Cu 3 O 7-δ single crystal with the propose of to disclose the correlation between the zero resistance, T R0 (H) and the magnetic irreversibility, T irr (H) temperatures. The R(T,H) measurements were performed with a PPMS with the measurement current density applied parallel to the sample ab plane. The M ZFC (T) and M FCC (T) measurements were performed with a commercial SQUID magnetometer. For the both measurements H ≤ 50kOe were applied parallel to the c axis of the sample. The contrasting of the T irr (H) and T R0 (H) data profile at H-T diagram shows that for H ≤ 5kOe the T R0 (H) data falls systematically underneath of the T irr (H) data and for H > 5kOe the T R0 (H) data matches to the T irr (H) data. We attributed to the establishment of a superconducting granular scenario provided for Ca doping as responsible for the observation of these features. At this scenario, T irr (H) and T R0 (H) do not depend of the same parts of the sample. While the T irr (H) depends on well coupled grain clusters the T R0 (H) depends on grain arrays traversing the whole sample. The granular aspect of this result is discussed at the light of the superconducting glass theories

A PV temperature prediction model for BIPV configurations, comparison with other models and experimental results

OpenAIRE

Kaplanis, Socrates; Kaplani, Eleni

2018-01-01

The temperatures of c-Si and pc-Si BIPV configurations of different manufacturers were studied when operating under various environmental conditions. The BIPV configurations formed part of the roof in a Zero Energy Building, (ZEB), hanged over windows with varying inclination on a seasonal basis and finally two identical 0.5kWp PV generators were mounted on a terrace in two modes: fixed inclination and sun-tracking. The PV and ambient temperatures, Tpv and Ta, respectively, the intensity of t...

Evaluation of a novel noninvasive continuous core temperature measurement system with a zero heat flux sensor using a manikin of the human body.

Science.gov (United States)

Brandes, Ivo F; Perl, Thorsten; Bauer, Martin; Bräuer, Anselm

2015-02-01

Reliable continuous perioperative core temperature measurement is of major importance. The pulmonary artery catheter is currently the gold standard for measuring core temperature but is invasive and expensive. Using a manikin, we evaluated the new, noninvasive SpotOn™ temperature monitoring system (SOT). With a sensor placed on the lateral forehead, SOT uses zero heat flux technology to noninvasively measure core temperature; and because the forehead is devoid of thermoregulatory arteriovenous shunts, a piece of bone cement served as a model of the frontal bone in this study. Bias, limits of agreements, long-term measurement stability, and the lowest measurable temperature of the device were investigated. Bias and limits of agreement of the temperature data of two SOTs and of the thermistor placed on the manikin's surface were calculated. Measurements obtained from SOTs were similar to thermistor values. The bias and limits of agreement lay within a predefined clinically acceptable range. Repeat measurements differed only slightly, and stayed stable for hours. Because of its temperature range, the SOT cannot be used to monitor temperatures below 28°C. In conclusion, the new SOT could provide a reliable, less invasive and cheaper alternative for measuring perioperative core temperature in routine clinical practice. Further clinical trials are needed to evaluate these results.

PEEK: An excellent precursor for activated carbon production for high temperature application

International Nuclear Information System (INIS)

Cansado, I.P.P.; Goncalves, F.A.M.M.; Nabais, J.M.V.; Ribeiro Carrott, M.M.L.; Carrott, P.J.M.

2009-01-01

A series of activated carbons (AC) with high apparent surface area and very high micropore volumes were prepared from granulated PEEK (poly[oxy-1,4-phenylene-oxy-1,4-phenylene-carbonyl-1,4-phenylene]) by physical activation with CO 2 at different temperatures and different activation times. The carbonisation yields at 873, 1073 and 1173 K were 57, 52 and 51%. As the activation temperature increased, between 873 and 1173 K, the burn-off, the micropore volume and mean pore size increased too. Those prepared at 1173 K, with 74% burn-off, present an extremely high apparent surface area (2874 m 2 g - 1 ) and a very high micropore volume (1.27 cm 3 g - 1 ). The presence of pyrone groups, identified by FTIR, on the AC surface corroborates the prevalence of a basic point of zero charge, always higher than 9.2. The thermal stability was checked by thermogravimetric analysis and as the carbonisation temperature increased the thermal stability of the char increased too. All AC obtained from PEEK by physical activation at 1173 K are thermally resistant, as at 1073 K the loss of the initial mass was less than 15%. The collective results confirm that PEEK is an excellent precursor for preparing AC with a high carbonisation yield, a high micropore volume and apparent surface area and a very high resistance at elevated temperature. (author)

Characterization of the inhomogeneous barrier distribution in a Pt/(100)β-Ga2O3 Schottky diode via its temperature-dependent electrical properties

Science.gov (United States)

Jian, Guangzhong; He, Qiming; Mu, Wenxiang; Fu, Bo; Dong, Hang; Qin, Yuan; Zhang, Ying; Xue, Huiwen; Long, Shibing; Jia, Zhitai; Lv, Hangbing; Liu, Qi; Tao, Xutang; Liu, Ming

2018-01-01

β-Ga2O3 is an ultra-wide bandgap semiconductor with applications in power electronic devices. Revealing the transport characteristics of β-Ga2O3 devices at various temperatures is important for improving device performance and reliability. In this study, we fabricated a Pt/β-Ga2O3 Schottky barrier diode with good performance characteristics, such as a low ON-resistance, high forward current, and a large rectification ratio. Its temperature-dependent current-voltage and capacitance-voltage characteristics were measured at various temperatures. The characteristic diode parameters were derived using thermionic emission theory. The ideality factor n was found to decrease from 2.57 to 1.16 while the zero-bias barrier height Φb0 increased from 0.47 V to 1.00 V when the temperature was increased from 125 K to 350 K. This was explained by the Gaussian distribution of barrier height inhomogeneity. The mean barrier height Φ ¯ b0 = 1.27 V and zero-bias standard deviation σ0 = 0.13 V were obtained. A modified Richardson plot gave a Richardson constant A* of 36.02 A.cm-2.K-2, which is close to the theoretical value of 41.11 A.cm-2.K-2. The differences between the barrier heights determined using the capacitance-voltage and current-voltage curves were also in line with the Gaussian distribution of barrier height inhomogeneity.

Does zero-water discharged technology enhance culture performance of pacific white shrimp (Litopenaeus vannamei Boone.)?

Science.gov (United States)

Suantika, Gede; Anggraeni, Jayanty; Hasby, Fahri Azhari; Yanuwiarti, Ni Putu Indah

2014-03-01

Litopenaeus vannamei or white leg shrimp is an introduced shrimp which has successfully cultured in Indonesia. In Indonesia, L. vannamei is commonly cultured on outdoor/earthen pond that requires renewal of water, less control in term of water quality and disease and attributed to unpredictable yield production. Based on the existing culture condition, a system that enable to minimize water consumption, improve the hygiene of the culture and at the same time maintain a more stable yield production is urgent to be developed by using a zero water discharge system. The system consists of: (a) culture tank - to retain and culture the shrimp; (b) CaCO3 grained - buffering agent and substrate of nitrifying bacteria; (c) aeration line - to provide O2 and homogenize the culture; (d) ancho (feeding) - to control an appropriate feed; (e) nitrifying bacteria adding - to consume ammonium and nitrite then convert it to nitrate, and also control pathogen Vibrio sp.; (f) diatom microalgae (Chaetoceros gracilis) - to uptake nitrate, bacteriostatic agent, feed source, provide O2 and shading. In this study, there were 2 treatments: the static culture (batch) system was set as control (K) (in 70 PL/m2), and culture system with zero-water discharge system which was inoculated by 0.02% v/v 106 CFU/ml of mixed culture nitrifying bacteria and diatom microalgae in 70 PL/m2 (P1). The white leg shrimp used in this experiment was at post larvae (PL) 10 and cultured in a batch system (1 × 1 × 0.5 m3 pond) during 2 months. Several parameters including survival rate, mean body weight, and water quality (salinity, temperature, pH, DO, ammonium, nitrite, and nitrate) were measured. Based on the results, biomass of P1 (237.12 ± 31.11) gram is significantly higher than control (K) (180.80 ± 12.26) gram (Pshrimp post larvae, except ammonium concentration in control (K) (2.612 ± 0.56) mg/L which is significantly different from P1 (1.287 ± 0.49) mg/L. Based on this research, zero-water discharge

The quenched limit of lattice QCD at non-zero baryon number

International Nuclear Information System (INIS)

Engels, J.; Kaczmarek, O.; Karsch, F.; Laermann, E.

1999-01-01

We discuss the thermodynamics of gluons in the background of static quark sources. In order to do so we formulate the quenched limit of QCD at non-zero baryon number. A first numerical analysis of this system shows that it undergoes a smooth deconfining transition. We find evidence for a region of coexisting phases that becomes broader with increasing baryon number density. Although the action is in our formulation explicitly Z(3) symmetric the Polyakov loop expectation value becomes non-zero already in the low temperature phase. It indicates that the heavy quark potential stays finite at large distances, i.e. the string between static quarks breaks at non-zero baryon number density already in the hadronic phase

Spin waves in terbium. III. Magnetic anisotropy at zero wave vector

DEFF Research Database (Denmark)

Houmann, Jens Christian Gylden; Jensen, J.; Touborg, P.

1975-01-01

The energy gap at zero wave vector in the spin-wave dispersion relation of ferromagnetic. Tb has been studied by inelastic neutron scattering. The energy was measured as a function of temperature and applied magnetic field, and the dynamic anisotropy parameters were deduced from the results...... the effects of zero-point deviations from the fully aligned ground state, and we tentatively propose polarization-dependent two-ion couplings as their origin........ The axial anisotropy is found to depend sensitively on the orientation of the magnetic moments in the basal plane. This behavior is shown to be a convincing indication of considerable two-ion contributions to the magnetic anisotropy at zero wave vector. With the exception of the sixfold basal...

Isobaric specific heat capacity of water and aqueous cesium chloride solutions for temperatures between 298 K and 370 K at p = 0.1 MPa

International Nuclear Information System (INIS)

Lourenco, M.J.V.; Santos, F.J.V.; Ramires, M.L.V.; Nieto de Castro, C.A.

2006-01-01

There has been some controversy regarding the uncertainty of measurements of thermal properties using differential scanning calorimeters, namely heat capacity of liquids. A differential scanning calorimeter calibrated in enthalpy and temperature was used to measure the isobaric specific heat capacity of water and aqueous solutions of cesium chloride, in the temperature range 298 K to 370 K, for molalities up 3.2 mol . kg -1 , at p = 0.1 MPa, with an estimated uncertainty (ISO definition) better than 1.1%, at a 95% confidence level. The measurements are completely traceable to SI units of energy and temperature. The results obtained were correlated as a function of temperature and molality and compared with other authors, obtained by different methods and permit to conclude that a DSC calibrated by Joule effect is capable of very accurate measurements of the isobaric heat capacity of liquids, traceable to SI units of measurement

Electric resistance of nickel and niobium in the temperature range of 300-1300 K

International Nuclear Information System (INIS)

Novikov, I.I.; Roshchupkin, V.V.; Mozgovoj, A.G.; Semashko, N.A.

1982-01-01

The results of experimental investigation of nickel and niobium electric resistance on the wire samples by the potentiometric method in the temperature range of 300-1300 K are presented. Experimental data processing by the least square method is carried out; approximating equations of temperature dependence of the nickel and niobium electric resistance are prepared

Mass loss from the K dwarf in V471 Tauri

International Nuclear Information System (INIS)

Mullan, D.J.; Bruhweiler, F.; Sion, E.M.

1988-01-01

Spectra of MgII h and k have been obtained for V471 Tau at phases zero (K dwarf in front) and 0.5 (white dwarf in front). At phase zero, strong blueshifted absorption is present, suggestive of a wind from the K dwarf with terminal velocity 600-700 km/sec and mass loss rate at least three orders of magnitude greater than solar. Discrete blue-shifted absorption features occur at velocities of about 200 and 500 km/sec. At phase 0.5, the blueshifted absorption is much weaker, although still detectable

Generalized partition function zeros of 1D spin models and their critical behavior at edge singularities

International Nuclear Information System (INIS)

Dalmazi, D; Sa, F L

2010-01-01

Here we study the partition function zeros of the one-dimensional Blume-Emery-Griffiths model close to their edge singularities. The model contains four couplings (H, J, Δ, K) including the magnetic field H and the Ising coupling J. We assume that only one of the three couplings (J, Δ, K) is complex and the magnetic field is real. The generalized zeros z i tend to form continuous curves on the complex z-plane in the thermodynamic limit. The linear density at the edges z E diverges usually with ρ(z) ∼ |z - z E | σ and σ = -1/2. However, as in the case of complex magnetic fields (Yang-Lee edge singularity), if we have a triple degeneracy of the transfer matrix eigenvalues a new critical behavior with σ = -2/3 can appear as we prove here explicitly for the cases where either Δ or K is complex. Our proof applies for a general three-state spin model with short-range interactions. The Fisher zeros (complex J) are more involved; in practice, we have not been able to find an explicit example with σ = -2/3 as far as the other couplings (H, Δ, K) are kept as real numbers. Our results are supported by numerical computations of zeros. We show that it is absolutely necessary to have a non-vanishing magnetic field for a new critical behavior. The appearance of σ = -2/3 at the edge closest to the positive real axis indicates its possible relevance for tricritical phenomena in higher-dimensional spin models.

The Trouble with Zero

Science.gov (United States)

Lewis, Robert

2015-01-01

The history of the number zero is an interesting one. In early times, zero was not used as a number at all, but instead was used as a place holder to indicate the position of hundreds and tens. This article briefly discusses the history of zero and challenges the thinking where divisions using zero are used.

Evaporation of Cu, Sn, and S from Fe-C-Cu-Sn-S Liquid Alloys in the Temperature Range from 1513 K to 1873 K (1240 °C to 1600 °C)

Science.gov (United States)

Tafwidli, Fahmi; Choi, Moo-Eob; Yi, Sang-Ho; Kang, Youn-Bae

2018-06-01

Evaporation of Cu or Sn from liquid iron alloys containing C and S was experimentally investigated. The initial C concentration, [pct C]0, in the liquid alloy was varied from zero to C saturation, and the evaporation temperature was varied from 1513 K to 1773 K (1240 °C to 1500 °C). Along with the report by one of the present authors, the evaporation mechanism of Cu and Sn from liquid Fe-C-S alloy is proposed, after a modification from the previous mechanism. It was proposed that Cu and Sn evaporate as Cu(g) and Sn(g) and also evaporate as CuS(g) and SnS(g), which are more volatile species. Therefore, availability of S in the alloy affects the overall evaporation rate of Cu and Sn. At the same time, C in the alloy also forms volatile carbosulfides CS(g) and CS2(g), thereby competing with Cu and Sn. Moreover, C increases the activity coefficients of Cu, Sn, and S. This increases the thermodynamic driving force for the formation of CuS(g) and SnS(g). Therefore, increasing [pct C] partly accelerates the evaporation rate of Cu and Sn by increasing the activity coefficient but partly decelerates the evaporation rate by lowering the available S content. S partly accelerates the evaporation rate by increasing the available S for the sulfide gas species but partly decelerates the evaporation rate due to the surface poisoning effect. Increasing the reaction temperature increases the overall evaporation rate. All these facts were taken into account in order to develop an evaporation rate model. This model was extended from the present authors' previous one by taking into account (1) CS(g), S(g), and CS2(g) (therefore, the following species were considered as dominant evaporating species: Cu(g), CuS(g), Sn(g), SnS(g), S(g), CS(g), and CS2(g)); (2) the effect of C and temperature on the activity coefficients of Cu, Sn, and S; (3) the effect of C and temperature on the density of the liquid alloy; and (4) the effect of temperature on the S adsorption coefficient. This revised

Evaporation of Cu, Sn, and S from Fe-C-Cu-Sn-S Liquid Alloys in the Temperature Range from 1513 K to 1873 K (1240 °C to 1600 °C)

Science.gov (United States)

Tafwidli, Fahmi; Choi, Moo-Eob; Yi, Sang-Ho; Kang, Youn-Bae

2018-02-01

Evaporation of Cu or Sn from liquid iron alloys containing C and S was experimentally investigated. The initial C concentration, [pct C]0, in the liquid alloy was varied from zero to C saturation, and the evaporation temperature was varied from 1513 K to 1773 K (1240 °C to 1500 °C). Along with the report by one of the present authors, the evaporation mechanism of Cu and Sn from liquid Fe-C-S alloy is proposed, after a modification from the previous mechanism. It was proposed that Cu and Sn evaporate as Cu(g) and Sn(g) and also evaporate as CuS(g) and SnS(g), which are more volatile species. Therefore, availability of S in the alloy affects the overall evaporation rate of Cu and Sn. At the same time, C in the alloy also forms volatile carbosulfides CS(g) and CS2(g), thereby competing with Cu and Sn. Moreover, C increases the activity coefficients of Cu, Sn, and S. This increases the thermodynamic driving force for the formation of CuS(g) and SnS(g). Therefore, increasing [pct C] partly accelerates the evaporation rate of Cu and Sn by increasing the activity coefficient but partly decelerates the evaporation rate by lowering the available S content. S partly accelerates the evaporation rate by increasing the available S for the sulfide gas species but partly decelerates the evaporation rate due to the surface poisoning effect. Increasing the reaction temperature increases the overall evaporation rate. All these facts were taken into account in order to develop an evaporation rate model. This model was extended from the present authors' previous one by taking into account (1) CS(g), S(g), and CS2(g) (therefore, the following species were considered as dominant evaporating species: Cu(g), CuS(g), Sn(g), SnS(g), S(g), CS(g), and CS2(g)); (2) the effect of C and temperature on the activity coefficients of Cu, Sn, and S; (3) the effect of C and temperature on the density of the liquid alloy; and (4) the effect of temperature on the S adsorption coefficient. This revised

Comparison of thermal properties of fish collagen and bovine collagen in the temperature range 298-670K.

Science.gov (United States)

Gauza-Włodarczyk, Marlena; Kubisz, Leszek; Mielcarek, Sławomir; Włodarczyk, Dariusz

2017-11-01

The increased interest in fish collagen is a consequence of the risk of exposure to Creutzfeld-Jacob disease (CJD) and the bovine spongiform encephalopathy (BSE), whose occurrence is associated with prions carried by bovine collagen. Collagen is the main biopolymer in living organisms and the main component of the skin and bones. Until the discovery of the BSE, bovine collagen had been widely used. The BSE epidemic increased the interest in new sources of collagen such as fish skin collagen (FSC) and its properties. Although the thermal properties of collagen originating from mammals have been well described, less attention has been paid to the thermal properties of FSC. Denaturation temperature is a particularly important parameter, depending on the collagen origin and hydration level. In the reported experiment, the free water and bound water release processes along with thermal denaturation process were studied by means of the differential scanning calorimetry (DSC). Measurements were carried out using a DSC 7 instrument (Elmer-Perkin), in the temperature range 298-670K. The study material was FSC derived by acidic hydration method. The bovine Achilles tendon (BAT) collagen type I was used as the control material. The thermograms recorded revealed both, exothermic and endothermic peaks. For both materials, the peaks in the temperature range of 330-360K were assigned to the release of free water and bound water. The denaturation temperatures of FSC and BAT collagen were determined as 420K and 493K, respectively. Thermal decomposition process was observed at about 500K for FSC and at about 510K for BAT collagen. These results show that FSC is less resistant to high temperature than BAT collagen. Copyright © 2017 Elsevier B.V. All rights reserved.

Plasmon resonance enhanced temperature-dependent photoluminescence of Si-V centers in diamond

Energy Technology Data Exchange (ETDEWEB)

Cheng, Shaoheng [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China); Song, Jie; Wang, Qiliang; Liu, Junsong; Li, Hongdong, E-mail: hdli@jlu.edu.cn [State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012 (China); Zhang, Baolin [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China)

2015-11-23

Temperature dependent optical property of diamond has been considered as a very important factor for realizing high performance diamond-based optoelectronic devices. The photoluminescence feature of the zero phonon line of silicon-vacancy (Si-V) centers in Si-doped chemical vapor deposited single crystal diamond (SCD) with localized surface plasmon resonance (LSPR) induced by gold nanoparticles has been studied at temperatures ranging from liquid nitrogen temperature to 473 K, as compared with that of the SCD counterpart in absence of the LSPR. It is found that with LSPR the emission intensities of Si-V centers are significantly enhanced by factors of tens and the magnitudes of the redshift (width) of the emissions become smaller (narrower), in comparison with those of normal emissions without plasmon resonance. More interestingly, these strong Si-V emissions appear remarkably at temperatures up to 473 K, while the spectral feature was not reported in previous studies on the intrinsic Si-doped diamonds when temperatures are higher than room temperature. These findings would lead to reaching high performance diamond-based devices, such as single photon emitter, quantum cryptography, biomarker, and so forth, working under high temperature conditions.

Magic angle spinning NMR below 6 K with a computational fluid dynamics analysis of fluid flow and temperature gradients

Science.gov (United States)

Sesti, Erika L.; Alaniva, Nicholas; Rand, Peter W.; Choi, Eric J.; Albert, Brice J.; Saliba, Edward P.; Scott, Faith J.; Barnes, Alexander B.

2018-01-01

We report magic angle spinning (MAS) up to 8.5 kHz with a sample temperature below 6 K using liquid helium as a variable temperature fluid. Cross polarization 13C NMR spectra exhibit exquisite sensitivity with a single transient. Remarkably, 1H saturation recovery experiments show a 1H T1 of 21 s with MAS below 6 K in the presence of trityl radicals in a glassy matrix. Leveraging the thermal spin polarization available at 4.2 K versus 298 K should result in 71 times higher signal intensity. Taking the 1H longitudinal relaxation into account, signal averaging times are therefore predicted to be expedited by a factor of >500. Computer assisted design (CAD) and finite element analysis were employed in both the design and diagnostic stages of this cryogenic MAS technology development. Computational fluid dynamics (CFD) models describing temperature gradients and fluid flow are presented. The CFD models bearing and drive gas maintained at 100 K, while a colder helium variable temperature fluid stream cools the center of a zirconia rotor. Results from the CFD were used to optimize the helium exhaust path and determine the sample temperature. This novel cryogenic experimental platform will be integrated with pulsed dynamic nuclear polarization and electron decoupling to interrogate biomolecular structure within intact human cells.

Mechanical properties of polymer matrix composites at 77 K and at room temperature after irradiation with 60Co γ-rays

International Nuclear Information System (INIS)

Egusa, S.; Hagiwara, M.

1986-01-01

Ten different polymer matrix composites were irradiated with 60 Co γ-rays at room temperature, and were examined with regard to the mechanical properties at 77 K and at room temperature. The radiation resistance of these composites depends primarily on the radiation resistance of matrix resins, which increases in the order diglycidyl ether of bisphenol A < tetraglycidyl diaminodiphenyl methane < Kerimid 601. Comparison of the mechanical properties tested at 77 K and at room temperature demonstrates that the extent of radiation-induced decrease in the composite strength is appreciably greater in the 77 K test than in the room temperature test. (author)

Pyroelectric Properties of Potassium and Rubidium Titanyl-Arsenate Single Crystals in the Temperature Range of 4.2-300 K

International Nuclear Information System (INIS)

Shaldin, Yu. V.; Matyjasik, S.; Novikova, N. E.; Tseitlin, M.; Mozhaev, E.; Roth, M.

2010-01-01

The temperature dependences of the pyroelectric coefficients of KTiOAsO 4 and RbTiOAsO 4 single crystals grown by flux crystallization have been investigated in the temperature range of 4.2-300 K. With an increase in temperature, superionic conductivity first arises in KTiOAsO4 (at T > 200 K) and then (at T > 270 K) in RbTiOAsO 4 . This conductivity is much higher in the samples polarized at T = 4.2 K. An exponential change in the crystal resistivity along the polar direction is simultaneously observed. The results of measurements in the range of 4.2-200 K indicate larger values of pyroelectric coefficients when compared with potassium and rubidium titanyl-phosphate crystals. A correlation between the pyroelectric coefficients and a change in the lattice constants at isomorphic substitutions of K atoms for Rb and P atoms for As has been revealed within the symmetry approach.

Pyroelectric Properties of Potassium and Rubidium Titanyl-Arsenate Single Crystals in the Temperature Range of 4.2-300 K

Energy Technology Data Exchange (ETDEWEB)

Shaldin, Yu. V., E-mail: yuri1999@rambler.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Matyjasik, S. [International Laboratory of Strong Magnetic Fields and Low Temperatures (Poland); Novikova, N. E. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Tseitlin, M.; Mozhaev, E. [Ariel University Center of Samaria (Israel); Roth, M. [Hebrew University, School of Applied Sciences (Israel)

2010-11-15

The temperature dependences of the pyroelectric coefficients of KTiOAsO{sub 4} and RbTiOAsO{sub 4} single crystals grown by flux crystallization have been investigated in the temperature range of 4.2-300 K. With an increase in temperature, superionic conductivity first arises in KTiOAsO4 (at T > 200 K) and then (at T > 270 K) in RbTiOAsO{sub 4}. This conductivity is much higher in the samples polarized at T = 4.2 K. An exponential change in the crystal resistivity along the polar direction is simultaneously observed. The results of measurements in the range of 4.2-200 K indicate larger values of pyroelectric coefficients when compared with potassium and rubidium titanyl-phosphate crystals. A correlation between the pyroelectric coefficients and a change in the lattice constants at isomorphic substitutions of K atoms for Rb and P atoms for As has been revealed within the symmetry approach.

Field-induced interplanar magnetic correlations in the high-temperature superconductor La1.88Sr0.12CuO4

DEFF Research Database (Denmark)

Rømer, A. T.; Jensen, P.; Jacobsen, H.

2015-01-01

We present neutron-scattering studies of the interplanar magnetic correlations in the high-temperature superconductor La1.88Sr0.12CuO4 (Tc=27 K). The correlations are studied both in a magnetic field applied perpendicular to the CuO2 planes, and in zero field under different cooling conditions. We...

Adrenaline-induced colonic K+ secretion is mediated by KCa1.1 (BK) channels

DEFF Research Database (Denmark)

Sørensen, Mads Vaarby; Sausbier, Matthias; Ruth, Peter

2010-01-01

. However, the secretory K(+) channel responsible for cAMP-induced K(+) secretion remains to be defined. In this study we used the Ussing chamber to identify adrenaline-induced electrogenic K(+) secretion. We found that the adrenaline-induced electrogenic ion secretion is a compound effect dominated...... variants in colonic enterocytes (STREX and ZERO). Importantly, the ZERO variant known to be activated by cAMP is differentially up-regulated in enterocytes from animals on a high K(+) diet. In summary, these results strongly suggest that the adrenaline-induced distal colonic K(+) secretion is mediated...

Revisiting the definition of the electronic chemical potential, chemical hardness, and softness at finite temperatures

Energy Technology Data Exchange (ETDEWEB)

Franco-Pérez, Marco, E-mail: qimfranco@hotmail.com, E-mail: jlgm@xanum.uam.mx [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, México D. F. 09340 (Mexico); Department of Chemistry, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Gázquez, José L., E-mail: qimfranco@hotmail.com, E-mail: jlgm@xanum.uam.mx [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, México D. F. 09340 (Mexico); Ayers, Paul W. [Department of Chemistry, McMaster University, Hamilton, Ontario L8S 4M1 (Canada); Vela, Alberto [Departamento de Química, Centro de Investigación y de Estudios Avanzados (Cinvestav), Av. Instituto Politécnico Nacional 2508, México D. F. 07360 (Mexico)

2015-10-21

We extend the definition of the electronic chemical potential (μ{sub e}) and chemical hardness (η{sub e}) to finite temperatures by considering a reactive chemical species as a true open system to the exchange of electrons, working exclusively within the framework of the grand canonical ensemble. As in the zero temperature derivation of these descriptors, the response of a chemical reagent to electron-transfer is determined by the response of the (average) electronic energy of the system, and not by intrinsic thermodynamic properties like the chemical potential of the electron-reservoir which is, in general, different from the electronic chemical potential, μ{sub e}. Although the dependence of the electronic energy on electron number qualitatively resembles the piecewise-continuous straight-line profile for low electronic temperatures (up to ca. 5000 K), the introduction of the temperature as a free variable smoothens this profile, so that derivatives (of all orders) of the average electronic energy with respect to the average electron number exist and can be evaluated analytically. Assuming a three-state ensemble, well-known results for the electronic chemical potential at negative (−I), positive (−A), and zero values of the fractional charge (−(I + A)/2) are recovered. Similarly, in the zero temperature limit, the chemical hardness is formally expressed as a Dirac delta function in the particle number and satisfies the well-known reciprocity relation with the global softness.

Effect of Low Temperature on a 4 W/60 K Pulse-Tube Cryocooler for Cooling HgCdTe Detector

Science.gov (United States)

Zhang, Ankuo; Liu, Shaoshuai; Wu, Yinong

2018-04-01

Temperature is an extremely important parameter for the material of the space-borne infrared detector. To cool an HgCdTe-infrared detector, a Stirling-type pulse-tube cryocooler (PTC) has been developed based on a great deal of numerical simulations, which are performed to investigate the thermodynamic behaviors of the PTC. The effects of different low temperatures are presented to analyze different energy flows, losses, phase shifts, and impedance matching of the PTC at a temperature range of 40-120 K, where woven wire screens are used. Finally, a high-efficiency coaxial PTC has been designed, built, and tested, operating around 60 K after a number of theoretical and experimental studies. The PTC can offer a no-load refrigeration temperature of 40 K with an input electric power of 150 W, and a cooling power of 4 W at 60 K is obtained with Carnot efficiency of 12%. In addition, a comparative study of simulation and experiment has been carried out, and some studies on reject temperatures have been presented for a thorough understanding of the PTC system.

K0/K+ ratio in relativistic heavy-ion collisions

International Nuclear Information System (INIS)

Ivanov, Yu.B.; Russkikh, V.N.

1996-11-01

It is shown that ratio of production yields of K 0 and K + mesons in collisions of isotopically asymmetric nuclei at incident energies ∼ 1 GeV/nucleon is related directly enough to temperature of nuclear matter at the initial stage of the collision. Sensitivity of the K 0 /K + ratio to the temperature variation is analyzed. Ambiguities, associated with interpretation of this quantity as a probe of nuclear temperature, are discussed. It is argued that the K 0 /K + ratio is a fairly model-independent quantity, provided channels with Δ isobars dominate the kaon production. (orig.)

Neutron diffraction study of high temperature phase of K2SeO4

International Nuclear Information System (INIS)

Iwata, Yutaka; Koyano, Nobumitsu; Shibuya, Iwao; Hidaka, Masanori; Okazaki, Atsushi.

1984-01-01

The crystal structure of high-temperature phase of K 2 SeO 4 has been determined by means of single crystal neutron diffraction. The space group is P6 3 /mmc of hexagonal system with two formula units per unit cell. The structure is characterized by an averaged dispositions of SeO 4 tetrahedra with one of its Se-O bonds pointing parallel and antiparallel to the hexagonal c-axis in addition to the split distribution of potassium atoms. Heavily distorted distribution of oxygen atoms in SeO 4 is observed in Fourier maps corrersponding to split positions and reorientational motion of tetrahedra. This disordered arrangement is found to have close relation with the room temperature orthorhombic structure. The hexagonal-orthorhombic phase transition of K 2 SeO 4 at 472 0 C is grouped to an order-disorder type. (author)

Polypyrrole/silver coaxial nanowire aero-sponges for temperature-independent stress sensing and stress-triggered Joule heating.

Science.gov (United States)

He, Weina; Li, Guangyong; Zhang, Shangquan; Wei, Yong; Wang, Jin; Li, Qingwen; Zhang, Xuetong

2015-04-28

To obtain ideal sensing materials with nearly zero temperature coefficient resistance (TCR) for self-temperature-compensated pressure sensors, we proposed an Incipient Network Conformal Growth (INCG) technology to prepare hybrid and elastic porous materials: the nanoparticles (NPs) are first dispersed in solvent to form an incipient network, another component is then introduced to coat the incipient network conformally via wet chemical route. The conformal coatings not only endow NPs with high stability but also offer them additional structural elasticity, meeting requirements for future generations of portable, compressive and flexible devices. The resultant polypyrrole/silver coaxial nanowire hybrid aero-sponges prepared via INCG technology have been processed into a piezoresistive sensor with highly sensing stability (low TCR 0.86 × 10(-3)/°C), sensitivity (0.33 kPa(-1)), short response time (1 ms), minimum detectable pressure (4.93 Pa) after suffering repeated stimuli, temperature change and electric heating. Moreover, a stress-triggered Joule heater can be also fabricated mainly by the PPy-Ag NW hybrid aero-sponges with nearly zero temperature coefficient.

The structure factor and the pair potential of liquid rubidium at temperatures between 450 K and 1,400 K

International Nuclear Information System (INIS)

Block de Priego, R.A.

1977-11-01

The structure factor S(Q) of liquid rubidium has been measured for temperatures between 450 K and 1400 K and pressures up to 200 atm. The corresponding densities varied between 1.42 and 0.98 g cm -3 . The incident energy of the neutrons was 3.4 MeV, the momentum transfer Q being 0.2 - 2.5 A -1 . A significant change in the order of the liquid has been registrated. Compressibility and electrical conductivity were derived from the structure factors and compared with the direct measured quantities, showing a good agreement. Further interpretation of the data was done by means of a hard core and a square well potential. Using these models it was already possible to get some information about the interactions between the rubidium atoms. A more exact calculation with a modified STLS model and a pseudopotential leads to a good description of the measured S(Q). In order to describe at high temperatures S(Q) for smaller values a new term had to be added to the pseudopotential. (orig.) [de

Signed zeros of Gaussian vector fields - density, correlation functions and curvature

CERN Document Server

Foltin, G

2003-01-01

We calculate correlation functions of the (signed) density of zeros of Gaussian distributed vector fields. We are able to express correlation functions of arbitrary order through the curvature tensor of a certain abstract Riemann Cartan or Riemannian manifold. As an application, we discuss one- and two-point functions. The zeros of a two-dimensional Gaussian vector field model the distribution of topological defects in the high-temperature phase of two-dimensional systems with orientational degrees of freedom, such as superfluid films, thin superconductors and liquid crystals.

Vertical Magnetic Levitation Force Measurement on Single Crystal YBaCuO Bulk at Different Temperatures

Science.gov (United States)

Celik, Sukru; Guner, Sait Baris; Ozturk, Kemal; Ozturk, Ozgur

Magnetic levitation force measurements of HTS samples are performed with the use of liquid nitrogen. It is both convenient and cheap. However, the temperature of the sample cannot be changed (77 K) and there is problem of frost. So, it is necessary to build another type of system to measure the levitation force high Tc superconductor at different temperatures. In this study, we fabricated YBaCuO superconducting by top-seeding-melting-growth (TSMG) technique and measured vertical forces of them at FC (Field Cooling) and ZFC (Zero Field Cooling) regimes by using our new designed magnetic levitation force measurement system. It was used to investigate the three-dimensional levitation force and lateral force in the levitation system consisting of a cylindrical magnet and a permanent cylindrical superconductor at different temperatures (37, 47, 57, 67 and 77 K).

Apollo-Soyuz pamphlet no. 8: Zero-g technology. [experimental designispace processing and aerospace engineering

Science.gov (United States)

Page, L. W.; From, T. P.

1977-01-01

The behavior of liquids in zero gravity environments is discussed with emphasis on foams, wetting, and wicks. A multipurpose electric furnace (MA-010) for the high temperature processing of metals and salts in zero-g is described. Experiments discussed include: monolectic and synthetic alloys (MA-041); multiple material melting point (MA-150); zero-g processing of metals (MA-070); surface tension induced convection (MA-041); halide eutectic growth; interface markings in crystals (MA-060); crystal growth from the vapor phase (MA-085); and photography of crystal growth (MA-028).

An in situ Raman spectroscopy system for long-term corrosion experiments in high temperature water up to 673 K

International Nuclear Information System (INIS)

Domae, Masafumi; Tani, Jun-ichi; Fujiwara, Kazutoshi; Katsumura, Yosuke

2006-01-01

A Raman spectroscopy system has been developed, in order to identify oxides formed on the surfaces of metals and steels in high temperature water up to 673 K. A supercritical water loop system including a Raman cell was installed. The design of the loop system is up to 673 K and 40 MPa. The Raman cell has a diamond window without window-to-metal packing. Raman spectrum of alumina plate was measured at room temperature, at 523 and at 673 K under pressure of 25 MPa. A long-term measurement was also performed at 523 K and 25 MPa for 117.5 h. In all cases intense Raman peaks attributed to alumina were observed. Raman spectrum of anatase particles in suspension was measured at 673 K and 25 MPa. The results show that the Raman spectroscopy system developed in the present study works well not only for plate sample but also for suspension. Raman spectra observed for titanium plate in high temperature water of 673 K and 25 MPa show growth of several Raman peaks with time up to 257 h. The peaks disappeared after cooled down to room temperature. The experimental results have demonstrated importance of in situ Raman spectroscopy. (author)

Design and construction of an adiabatic calorimeter for samples of less than 1 cm3 in the temperature range T = 15 K to T = 350 K

International Nuclear Information System (INIS)

Lang, Brian E.; Boerio-Goates, Juliana; Woodfield, Brian F.

2006-01-01

A small-scale adiabatic calorimeter has been constructed as part of a larger project to study the thermodynamics of nanomaterials and to facilitate heat capacity measurements on samples of insufficient quantity to run on our current large-scale adiabatic apparatus. This calorimeter is designed to measure the heat capacity of samples whose volume is less than 0.8 cm 3 over a temperature range of T = 13 K to T = 350 K. Heat capacity results on copper, sapphire, and benzoic acid show the accuracy of the measurements to be better than ±0.4% for temperatures higher than T = 50 K. The reproducibility of these measurements is generally better than ±0.25%

Low temperature magnetic characterization of EuO1-x

Science.gov (United States)

Rimal, Gaurab; Tang, Jinke

EuO is a widely studied magnetic semiconductor. It is an ideal case of a Heisenberg ferromagnet as well as a model magnetic polaron system. The interesting aspect of this material is the existance of magnetic polarons in the low temperature region. We study the properties of oxygen deficient EuO prepared by pulsed laser deposition. Besides normal ferromagnetic transitions near 70K and 140K, we observe a different transition at 16K. We also observe a shift in the coercivity for field cooling versus zero field cooling. Possible mechanisms driving these behaviors will be discussed. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering (DEFG02-10ER46728) and by the School of Energy Resources of the University of Wyoming.

Kaolinite-supported nanoscale zero-valent iron for removal of Pb2+ from aqueous solution: reactivity, characterization and mechanism.

Science.gov (United States)

Zhang, Xin; Lin, Shen; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravendra

2011-05-01

The use of nanoscale zero-valent iron (nZVI) to remediate contaminated groundwater is limited due to its lack of durability and mechanical strength. To address this issue, 20% (w/w) nZVI was loaded onto kaolinite as a support material (K-nZVI). More than 96% of Pb(2+) was removed from aqueous solution using K-nZVI at an initial condition of 500 mg/L Pb(2+) within 30 min under the conditions of 10 g/L of K-nZVI, pH 5.10 and a temperature of 30 °C. To understand the mechanism of removal of Pb(2+), various techniques were implemented to characterize K-nZVI. Scanning electron microscopy (SEM) indicated that K-nZVI had a suitable dispersive state with a lower aggregation, where the mean specific surface area and average particle size as determined by the BET-N(2) method and X-ray diffraction (XRD), were 26.11 m(2)/g and 44.3 nm, respectively. The results obtained from XRD, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) indicated that a small number of iron oxides formed on the surface of K-nZVI, suggesting that free Pb(2+) was adsorbed onto K-nZVI and subsequently reduced to Pb(0). Copyright © 2011 Elsevier Ltd. All rights reserved.

Thermal conductivity and electrical resistivity of cadmium arsenide (Cd3As2) in the temperature range 4.2-40K1

International Nuclear Information System (INIS)

Bartkowski, K.; Ratalowicz, J.; Zdanowicz, W.

1986-01-01

Results on electrical resistivity and thermal conductivity measured in the temperature range 4.2-40 K are presented for single-crystal and polycrystalline samples of Cd 3 As 2 . Hall effect has been studied at temperatures of 4.2, 77, and 300K. The calculated value of the conduction electron concentration was in the range 1.87-1.95 10 24 m -3 . Electrical resistivity of all investigated samples was independent of temperature up to about 10K and increased slowsly at higher temperatures. The thermal conductivity shows a maximum in the region in which the lattice component of thermal conductivity dominates. The strong anistropy of the lattice component determines the anisotropy of the total thermal conductivity. The electronic component of thermal conductivity does not exhibit any anisotropy and shows a maximum at a temperature of about 300 K

Observation of the Zero Hall Plateau in a Quantum Anomalous Hall Insulator

Energy Technology Data Exchange (ETDEWEB)

Feng, Yang; Feng, Xiao; Ou, Yunbo; Wang, Jing; Liu, Chang; Zhang, Liguo; Zhao, Dongyang; Jiang, Gaoyuan; Zhang, Shou-Cheng; He, Ke; Ma, Xucun; Xue, Qi-Kun; Wang, Yayu

2015-09-16

We report experimental investigations on the quantum phase transition between the two opposite Hall plateaus of a quantum anomalous Hall insulator. We observe a well-defined plateau with zero Hall conductivity over a range of magnetic field around coercivity when the magnetization reverses. The features of the zero Hall plateau are shown to be closely related to that of the quantum anomalous Hall effect, but its temperature evolution exhibits a significant difference from the network model for a conventional quantum Hall plateau transition. We propose that the chiral edge states residing at the magnetic domain boundaries, which are unique to a quantum anomalous Hall insulator, are responsible for the novel features of the zero Hall plateau.

Systematic and controllable negative, zero, and positive thermal expansion in cubic Zr(1-x)Sn(x)Mo2O8.

Science.gov (United States)

Tallentire, Sarah E; Child, Felicity; Fall, Ian; Vella-Zarb, Liana; Evans, Ivana Radosavljević; Tucker, Matthew G; Keen, David A; Wilson, Claire; Evans, John S O

2013-08-28

We describe the synthesis and characterization of a family of materials, Zr1-xSnxMo2O8 (0 thermal expansion coefficient can be systematically varied from negative to zero to positive values. These materials allow tunable expansion in a single phase as opposed to using a composite system. Linear thermal expansion coefficients, αl, ranging from -7.9(2) × 10(-6) to +5.9(2) × 10(-6) K(-1) (12-500 K) can be achieved across the series; contraction and expansion limits are of the same order of magnitude as the expansion of typical ceramics. We also report the various structures and thermal expansion of "cubic" SnMo2O8, and we use time- and temperature-dependent diffraction studies to describe a series of phase transitions between different ordered and disordered states of this material.

The zeros of az2J″ν(z+bzJ′ν(z+cJν(z as functions of order

Directory of Open Access Journals (Sweden)

A. McD. Mercer

1992-01-01

Full Text Available If j″νk denotes the kth positive zero of the Bessel function J″ν(x, it has been shown recently by Lorch and Szego [2] that j″ν1 increases with ν in ν>0 and that (with k fixed in 2,3,… j″νk increases in 00. The present paper, by using a different kind of analysis, re-obtains these conclusions as a special case of a more general result concerning the positive zeros of the function az2J″ν(z+bzJ′ν(z+cJν(z. Here, the constants a, b and c are subject to certain mild restrictions.

Melting temperature, vapor density, and vapor pressure of molybdenum pentafluoride

Energy Technology Data Exchange (ETDEWEB)

Krause, Jr, R F; Douglas, T B [National Bureau of Standards, Washington, D.C. (USA). Inst. for Materials Research

1977-12-01

A sample of MoF/sub 5/ was prepared by reaction of MoF/sub 6/(g) and Mo(c). Melting curves of temperature against time established the melting temperature at zero impurity to be 318.85 K, the enthalpy of fusion to be 6.1 kJ mol/sup -1/ (+ - 5 per cent), and the cryoscopic impurity of the sample to be 0.15 mole per cent. In the presence of MoF/sub 6/(g) which was added to suppress disproportionation, the vapor density of MoF/sub 5/ over the liquid was measured by the transpiration method at 343, 363, and 383 K, the total MoF/sub 5/ that evaporated being determined by permanganate titration. The total vapor pressure of MoF/sub 5/ oligomers over the liquid was measured by a simple static method at 373 and 392 K, while melting temperatures were taken alternately to monitor possible contamination of the sample. Although the vapor pressures were adjusted for disproportionation, solution of MoF/sub 6/ in MoF/sub 5/ (1), and wall adsorption of MoF/sub 6/ their percentage uncertainty is probably several times that of the vapor densities. A combination of the two properties indicates the average extent of association of the saturated vapor to be near 2, which is the value for the dimer species (MoF/sub 5/)/sub 2/.

Phase Transformations and Phase Equilibria in the Fe-N System at Temperatures below 573 K

DEFF Research Database (Denmark)

Malinov, S.; Böttger, A.J.; Mittemeijer, E.J.

2001-01-01

The phase transformations of homogeneous Fe-N alloys of nitrogen contents from 10 to 26 at. pct were investigated by means of X-ray diffraction analysis upon aging in the temperature range from 373 to 473 K. It was found that precipitation of alpha double prime-Fe16N2 below 443 K does not only oc...

Phonon Anharmonicity of Germanium in the Temperature Range 80-880 K

Energy Technology Data Exchange (ETDEWEB)

Nelin, G; Nilsson, G

1974-06-15

Phonon frequency shifts and line widths in germanium have been studied in the temperature range 80 - 880 K by means of thermal neutron spectrometry. The results cannot be described in terms of the quasiharmonic approximation in which phonon frequencies are solely volume dependent. Theoretical calculations are found to be more satisfactory for the Raman frequency than for most other modes. A good account of the observed shifts is given by a proposal due to Barron according to which the relative frequency renormalization of a crystal is proportional to the total harmonic vibrational energy. An analysis of the gradients of measured dispersion relations in the principal symmetry directions at 80 K is presented. It is shown that accidental degeneracies may influence the dispersion

Zero and finite field μSR spin glass Ag:Mn

International Nuclear Information System (INIS)

Brown, J.A.; Heffner, R.H.; Leon, M.; Olsen, C.E.; Schillaci, M.E.; Dodds, S.A.; Estle, T.L.; MacLaughlin, D.E.

1981-01-01

In this paper we present μSR data taken in both zero and finite fields for a Ag:Mn (1.6 at%) spin glass sample. The data allow us to determine, in the context of a particular model, the fluctuation rate of the Mn ions as a function of temperature. This rate decreases smoothly but very rapidly near the glass temperature, Tsub(g). The corresponding behavior in Cu:Mn is more gradual. (orig.)

Temperature-specific inhibition of human red cell Na+/K+ ATPase by 2450-MHz microwave radiation

Energy Technology Data Exchange (ETDEWEB)

Allis, J.W.; Sinha-Robinson, B.L.

1987-01-01

The ATPase activity in human red blood cell membranes was investigated in vitro as a function of temperature and exposure to 2450-MHz continuous wave microwave radiation to confirm and extend a report of Na+ transport inhibition under certain conditions of temperature and exposure. Assays were conducted spectrophotometrically during microwave exposure with a custom-made spectrophotometer-waveguide apparatus. Temperature profiles of total ATPase and Ca+2 ATPase (ouabain-inhibited) activity between 17 and 31 degrees C were graphed as an Arrhenius plot. Each data set was fitted to two straight lines which intersect between 23 and 24 degrees C. The difference between the total and Ca+2 ATPase activities, which represented the Na+/K+ ATPase activity, was also plotted and treated similarly to yield an intersection near 25 degrees C. Exposure of membrane suspensions to electromagnetic radiation, at a dose rate of 6 W/kg and at five temperatures between 23 and 27 degrees C, resulted in an activity change only for the Na+/K+ ATPase at 25 degrees C. The activity decreased by approximately 35% compared to sham-irradiated samples. A possible explanation for the unusual temperature/microwave interaction is proposed.

Global IP6K1 deletion enhances temperature modulated energy expenditure which reduces carbohydrate and fat induced weight gain

Directory of Open Access Journals (Sweden)

Qingzhang Zhu

2017-01-01

Full Text Available Objective: IP6 kinases (IP6Ks regulate cell metabolism and survival. Mice with global (IP6K1-KO or adipocyte-specific (AdKO deletion of IP6K1 are protected from diet induced obesity (DIO at ambient (23 °C temperature. AdKO mice are lean primarily due to increased AMPK mediated thermogenic energy expenditure (EE. Thus, at thermoneutral (30 °C temperature, high fat diet (HFD-fed AdKO mice expend energy and gain body weight, similar to control mice. IP6K1 is ubiquitously expressed; thus, it is critical to determine to what extent the lean phenotype of global IP6K1-KO mice depends on environmental temperature. Furthermore, it is not known whether IP6K1 regulates AMPK mediated EE in cells, which do not express UCP1. Methods: Q-NMR, GTT, food intake, EE, QRT-PCR, histology, mitochondrial oxygen consumption rate (OCR, fatty acid metabolism assays, and immunoblot studies were conducted in IP6K1-KO and WT mice or cells. Results: Global IP6K1 deletion mediated enhancement in EE is impaired albeit not abolished at 30 °C. As a result, IP6K1-KO mice are protected from DIO, insulin resistance, and fatty liver even at 30 °C. Like AdKO, IP6K1-KO mice display enhanced adipose tissue browning. However, unlike AdKO mice, thermoneutrality only partly abolishes browning in IP6K1-KO mice. Cold (5 °C exposure enhances carbohydrate expenditure, whereas 23 °C and 30 °C promote fat oxidation in HFD-KO mice. Furthermore, IP6K1 deletion diminishes cellular fat accumulation via activation of the AMPK signaling pathway. Conclusions: Global deletion of IP6K1 ameliorates obesity and insulin resistance irrespective of the environmental temperature conditions, which strengthens its validity as an anti-obesity target. Keywords: IP6K, Obesity, Diabetes, Energy expenditure, β-oxidation

Temperature dependence of the domain wall magneto-Seebeck effect: avoiding artifacts of lead contributions

Science.gov (United States)

Fernández Scarioni, Alexander; Krzysteczko, Patryk; Sievers, Sibylle; Hu, Xiukun; Schumacher, Hans W.

2018-06-01

We study the resistive and thermopower signatures of a single domain wall in a magnetic nanowire in the temperature range from 4 K to 204 K. The results are compared to the anisotropic magnetoresistance (AMR) and anisotropic magneto-Seebeck (AMS) data of the whole permalloy nanowire. The AMS ratio of the nanowire reveals a sign change at a temperature of 98 K, while the AMR ratio is positive over the complete temperature range. This behavior is also observed for the domain wall, allowing an attribution of the measured signatures to the domain wall magneto-Seebeck and domain wall magnetoresistive contributions. However, the observed zero crossing of the AMS ratio, in both types of measurements is not expected for permalloy, since the Mott formula predicts a temperature dependency of the AMS identical to the AMR. We discuss the origin of this behavior and can attribute it to the contributions of the lead and the protective platinum layer used in our devices. A correction scheme is presented and applied. Such contributions could also play a role in the analysis of magneto-Seebeck effects in other nanoscale devices, such as the tunnel magneto-Seebeck effect of magnetic tunnel junctions.

Dusty plasma in a glow discharge in helium in temperature range of 5–300 K

Energy Technology Data Exchange (ETDEWEB)

Samoilov, I. S.; Baev, V. P.; Timofeev, A. V., E-mail: timofeevalvl@gmail.com; Amirov, R. Kh.; Kirillin, A. V.; Nikolaev, V. S.; Bedran, Z. V. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

2017-03-15

Dusty plasma structures in glow discharge in helium in the temperature range of 5–300 K are investigated experimentally. We have described the experimental setup that makes it possible to continuously vary the temperature regime. The method for experimental data processing has been described. We have measured interparticle distances in the temperature range of 9–295 K and compared them with the Debye radius. We indicate the ranges of variations in experimental parameters in which plasma–dust structures are formed and various types of their behavior are manifested (rotation, vibrations of structures, formation of vertical linear chains, etc.). The applicability of the Yukawa potential to the description of the structural properties of a dusty plasma in the experimental conditions is discussed.

Magnet design with 100-kA HTS STARS conductors for the helical fusion reactor

Science.gov (United States)

Yanagi, N.; Terazaki, Y.; Ito, S.; Tamura, H.; Hamaguchi, S.; Mito, T.; Hashizume, H.; Sagara, A.

2016-12-01

The high-temperature superconducting (HTS) option is employed for the conceptual design of the LHD-type helical fusion reactor FFHR-d1. The 100-kA-class STARS (Stacked Tapes Assembled in Rigid Structure) conductor is used for the magnet system including the continuously wound helical coils. Protection of the magnet system in case of a quench is a crucial issue and the hot-spot temperature during an emergency discharge is estimated based on the zero-dimensional and one-dimensional analyses. The number of division of the coil winding package is examined to limit the voltage generation. For cooling the HTS magnet, helium gas flow is considered and its feasibility is examined by simple analysis as a first step.

Enhancing Near Zero Volt Storage Tolerance of Lithium-ion Batteries

Science.gov (United States)

Crompton, Kyle R.

There are inherent safety risks associated with inactive lithium ion batteries leading to greater restrictions and regulations on shipping and storage. Maintaining all cells of a lithium ion battery at near zero voltage with an applied fixed resistive load is one promising approach which can lessen (and potentially eliminate) the risk of a lithium ion battery entering thermal runaway when in an inactive state. However, in a conventional lithium ion cell, a near zero cell voltage can be damaging if the anode electrochemical potential increases to greater than the potential where dissolution of the standard copper current collector occurs (i.e. 3.1 V vs. Li/Li+ at room temperature). Past approaches to yield lithium ion cells that are resilient to a near zero volt state of charge involve use of secondary active materials or alternative current collectors which have anticipated tradeoffs in terms of cell performance and cost. In the the present dissertation work the approach of managing the amount of reversible lithium in a cell during construction to prevent the anode potential from increasing to greater than 3.1 V vs. Li/Li+ during near zero volt storage is introduced. Anode pre-lithiation was used in LiCoO 2/MCMB pouch cells to appropriately manage the amount of reversible lithium so that there is excess reversible lithium compared to the cathodes intercalation capacity (reversible lithium excess cell or RLE cell). RLE LiCoO 2/MCMB cells maintained 99% of their original capacity after three, 3-day and three, 7-day storage periods at near zero volts under fixed load. A LiCoO2/MCMB pouch cell fabricated with a pre-lithiated anode also maintained its original discharge performance after three, 3-day storage periods under fixed load at 45°C. The strong recharge performance after near zero volt storage is attributed to the anode potential remaining below the copper dissolution potential during near zero volt storage as informed by reference electrode measurements. Pulse

Apparatus to measure emissivities of metallic films between 90K and room temperature

International Nuclear Information System (INIS)

Bekeris, V.I.; Ramos, E.D.; Sanchez, D.H.

1975-01-01

The development of multilayer insulations is aerospace and cryogenic required to know the emissivity of the metallic films used as reflective layers. This work describes an emissometer that measures the total hemispherical emissivity of metallic films evaporated on polyester substrates. The apparatus works at liquid oxigen temperatures and permits to get emissivities from 90K to room temperatures within a 15% precision. The emissometer construction and operation are described in detail. Results of measurements done on Single Aluminized Mylar are presented [pt

Apparatus to measure emissivities of metallic films between 90K and room temperature

Energy Technology Data Exchange (ETDEWEB)

Bekeris, V I [Nunez Univ. Nacional (Argentina). Faculdad de Ciencias Exactas Y Naturales; Ramos, E D [Santa Rosa Univ. Nacional (Argentina). Facultad de Ciencias Exactas Y Naturales; Sanchez, D H [Comision Nacional de Energia Atomica, San Carlos de Bariloche (Argentina). Centro Atomico Bariloche

1975-09-01

The development of multilayer insulations is aerospace and cryogenic required to know the emissivity of the metallic films used as reflective layers. This work describes an emissometer that measures the total hemispherical emissivity of metallic films evaporated on polyester substrates. The apparatus works at liquid oxigen temperatures and permits to get emissivities from 90K to room temperatures within a 15% precision. The emissometer construction and operation are described in detail. Results of measurements done on Single Aluminized Mylar are presented.

Unprecedented Integral-Free Debye Temperature Formulas: Sample Applications to Heat Capacities of ZnSe and ZnTe

Directory of Open Access Journals (Sweden)

R. Pässler

2017-01-01

Full Text Available Detailed analytical and numerical analyses are performed for combinations of several complementary sets of measured heat capacities, for ZnSe and ZnTe, from the liquid-helium region up to 600 K. The isochoric (harmonic parts of heat capacities, CVh(T, are described within the frame of a properly devised four-oscillator hybrid model. Additional anharmonicity-related terms are included for comprehensive numerical fittings of the isobaric heat capacities, Cp(T. The contributions of Debye and non-Debye type due to the low-energy acoustical phonon sections are represented here for the first time by unprecedented, integral-free formulas. Indications for weak electronic contributions to the cryogenic heat capacities are found for both materials. A novel analytical framework has been constructed for high-accuracy evaluations of Debye function integrals via a couple of integral-free formulas, consisting of Debye’s conventional low-temperature series expansion in combination with an unprecedented high-temperature series representation for reciprocal values of the Debye function. The zero-temperature limits of Debye temperatures have been detected from published low-temperature Cp(T data sets to be significantly lower than previously estimated, namely, 270 (±3 K for ZnSe and 220 (±2 K for ZnTe. The high-temperature limits of the “true” (harmonic lattice Debye temperatures are found to be 317 K for ZnSe and 262 K for ZnTe.

Design of a self-aligned, wide temperature range (300 mK-300 K) atomic force microscope/magnetic force microscope with 10 nm magnetic force microscope resolution

Energy Technology Data Exchange (ETDEWEB)

Karcı, Özgür [NanoMagnetics Instruments Ltd., Hacettepe - İvedik OSB Teknokent, 1368. Cad., No: 61/33, 06370, Yenimahalle, Ankara (Turkey); Department of Nanotechnology and Nanomedicine, Hacettepe University, Beytepe, 06800 Ankara (Turkey); Dede, Münir [NanoMagnetics Instruments Ltd., Hacettepe - İvedik OSB Teknokent, 1368. Cad., No: 61/33, 06370, Yenimahalle, Ankara (Turkey); Oral, Ahmet, E-mail: orahmet@metu.edu.tr [Department of Physics, Middle East Technical University, 06800 Ankara (Turkey)

2014-10-01

We describe the design of a wide temperature range (300 mK-300 K) atomic force microscope/magnetic force microscope with a self-aligned fibre-cantilever mechanism. An alignment chip with alignment groves and a special mechanical design are used to eliminate tedious and time consuming fibre-cantilever alignment procedure for the entire temperature range. A low noise, Michelson fibre interferometer was integrated into the system for measuring deflection of the cantilever. The spectral noise density of the system was measured to be ~12 fm/√Hz at 4.2 K at 3 mW incident optical power. Abrikosov vortices in BSCCO(2212) single crystal sample and a high density hard disk sample were imaged at 10 nm resolution to demonstrate the performance of the system.

Design of a self-aligned, wide temperature range (300 mK-300 K) atomic force microscope/magnetic force microscope with 10 nm magnetic force microscope resolution

International Nuclear Information System (INIS)

Karcı, Özgür; Dede, Münir; Oral, Ahmet

2014-01-01

We describe the design of a wide temperature range (300 mK-300 K) atomic force microscope/magnetic force microscope with a self-aligned fibre-cantilever mechanism. An alignment chip with alignment groves and a special mechanical design are used to eliminate tedious and time consuming fibre-cantilever alignment procedure for the entire temperature range. A low noise, Michelson fibre interferometer was integrated into the system for measuring deflection of the cantilever. The spectral noise density of the system was measured to be ∼12 fm/√Hz at 4.2 K at 3 mW incident optical power. Abrikosov vortices in BSCCO(2212) single crystal sample and a high density hard disk sample were imaged at 10 nm resolution to demonstrate the performance of the system

The first-to-zero-sound transition in non-superfluid liquid 4He

International Nuclear Information System (INIS)

Woods, A.D.B.; Svensson, E.C.; Martel, P.

1976-01-01

Neutron inelastic scattering from 4 He at T=2.3 K shows that for Q -1 'sound-wave' excitations propagate with the characteristics of ordinary or first sound while for Q > approximately 3nm -1 they propagate with the characteristics of zero sound. (Auth.)

Experimental investigation on tritium release from lithium titanate pebble under high temperature of 1073 K

Energy Technology Data Exchange (ETDEWEB)

Ochiai, Kentaro, E-mail: howartre@onid.oregonstate.edu [Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki (Japan); Edao, Yuki; Kawamura, Yoshinori [Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki (Japan); Hoshino, Tsuyoshi [Japan Atomic Energy Agency, Rokkasho-mura, Kamikita-gun, Aomori (Japan); Ohta, Masayuki; Sato, Satoshi; Konno, Chikara [Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki (Japan)

2015-10-15

Highlights: • We have performed the tritium recovery experiment with the DT neutron source at 1073 K. • The tritium recovery corresponded with the calculated tritium production. • The chemical form of recovered tritium is affected by the temperature and kind of sweep gas. • The recovered HT increases at higher temperature and dry hydrogen circumstance. - Abstract: The temperature of Li{sub 2}TiO{sub 3} pebble breeder in a fusion DEMO blanket is assumed to be more than 1000 K. For the investigation of tritium release from a Li{sub 2}TiO{sub 3} pebble breeder blanket at such a high temperature, we have carried out a tritium release experiment with the DT neutron source at the JAEA-FNS. The Li{sub 2}TiO{sub 3} pebble (1.0–1.2 mm in diameter) of 70 g was put into a stainless steel container and installed into an assembly stratified with beryllium and Li{sub 2}TiO{sub 3} layers. During the DT neutron irradiation, the temperature was kept at 1073 K with wire heaters in the blanket container. Helium gas including 1% hydrogen gas (H{sub 2}/He) mainly flowed inside the container as the purge gas. Two chemical forms, HT and HTO, of extracted tritium were separately collected during the DT neutron irradiation by using water bubblers and CuO bed. The tritium activity in the water bubbler was measured by a liquid scintillation counter. To investigate the effect of moisture in the purge gas, we also performed the same experiments with H{sub 2}O/He gas (H{sub 2}O content: 1%) or pure helium gas. From our experiment at 1073 K, in the case of the purge gas includes H{sub 2}, it is indicated that the increasing tendency of HT release is similar to that of the dry H{sub 2}/He.

Studies on the zeros of Bessel functions and methods for their computation: 2. Monotonicity, convexity, concavity, and other properties

Science.gov (United States)

Kerimov, M. K.

2016-07-01

This work continues the study of real zeros of first- and second-kind Bessel functions and Bessel general functions with real variables and orders begun in the first part of this paper (see M.K. Kerimov, Comput. Math. Math. Phys. 54 (9), 1337-1388 (2014)). Some new results concerning such zeros are described and analyzed. Special attention is given to the monotonicity, convexity, and concavity of zeros with respect to their ranks and other parameters.

Vapour pressure of D2O - Ice at temperatures below 237 K

International Nuclear Information System (INIS)

Heras, J.M.; Asensio, M.C.; Estiu, G.; Viscido, L.

1984-01-01

Accurate measurements of heavy water ice vapour pressures between 193 and 253 K have been carried out and an equation based on thermodynamic data has been derived in order to calculate the D 2 O-ice vapour pressures between 173 and 273 K. The agreement between our calculated vapour pressures and the available experimental data including those in this paper, is very good. The comparison between the theoretical calculations of H 2 O-ice and D 2 O-ice vapour pressures confirms the experimental evidence that H 2 O-ice is more volatile than D 2 O-ice at all temperatures in agreement with the vapour isotopic effect theory (VPIE).(author)

Magneto-transport in the zero-energy Landau level of single-layer and bilayer graphene

International Nuclear Information System (INIS)

Zeitler, U; Giesbers, A J M; Elferen, H J van; Kurganova, E V; McCollam, A; Maan, J C

2011-01-01

We present recent low-temperature magnetotransport experiments on single-layer and bilayer graphene in high magnetic field up to 33 T. In single layer graphene the fourfold degeneracy of the zero-energy Landau level is lifted by a gap opening at filling factor ν = 0. In bilayer graphene, we observe a partial lifting of the degeneracy of the eightfold degenerate zero-energy Landau level.

Low-temperature thermal transport and thermopower of monolayer transition metal dichalcogenide semiconductors

Science.gov (United States)

Sengupta, Parijat; Tan, Yaohua; Klimeck, Gerhard; Shi, Junxia

2017-10-01

We study the low temperature thermal conductivity of single-layer transition metal dichalcogenides (TMDCs). In the low temperature regime where heat is carried primarily through transport of electrons, thermal conductivity is linked to electrical conductivity through the Wiedemann-Franz law (WFL). Using a k.p Hamiltonian that describes the K and K{\\prime} valley edges, we compute the zero-frequency electric (Drude) conductivity using the Kubo formula to obtain a numerical estimate for the thermal conductivity. The impurity scattering determined transit time of electrons which enters the Drude expression is evaluated within the self-consistent Born approximation. The analytic expressions derived show that low temperature thermal conductivity (1) is determined by the band gap at the valley edges in monolayer TMDCs and (2) in presence of disorder which can give rise to the variable range hopping regime, there is a distinct reduction. Additionally, we compute the Mott thermopower and demonstrate that under a high frequency light beam, a valley-resolved thermopower can be obtained. A closing summary reviews the implications of results followed by a brief discussion on applicability of the WFL and its breakdown in context of the presented calculations.

Temperature behavior of electrical properties of high-k lead-magnesium-niobium titanate thin-films

Energy Technology Data Exchange (ETDEWEB)

Chen Wenbin, E-mail: cwb0201@163.com [Electromechanical Engineering College, Guilin University of Electronic Technology (China); McCarthy, Kevin G. [Department of Electrical and Electronic Engineering, University College Cork (Ireland); Copuroglu, Mehmet; O' Brien, Shane; Winfield, Richard; Mathewson, Alan [Tyndall National Institute, University College Cork (Ireland)

2012-05-01

This paper reports on the temperature dependence of the electrical properties of high-k lead-magnesium-niobium titanate thin films processed with different compositions (with and without nanoparticles) and with different annealing temperatures (450 Degree-Sign C and 750 Degree-Sign C). These characterization results support the ongoing investigation of the material's electrical properties which are necessary before the dielectric can be used in silicon-based IC applications.

Coupling between Solid 3He on Aerogel and Superfluid 3He in the Low Temperature Limit

International Nuclear Information System (INIS)

Bradley, D. I.; Fisher, S. N.; Guenault, A. M.; Haley, R. P.; Pickett, G. R.; Tsepelin, V.; Whitehead, R. C. V.; Skyba, P.

2006-01-01

We have cooled liquid 3He contained in a 98% open aerogel sample surrounded by bulk superfluid 3He-B at zero pressure to below 120 μK. The aerogel sample is placed in a quasiparticle blackbody radiator cooled by a Lancaster-style nuclear cooling stage to ∼200 μK. We monitor the temperature of the 3He inside the blackbody radiator using a vibrating wire resonator. We find that reducing the magnetic field on the aerogel sample causes substantial cooling of all the superfluid inside the blackbody radiator. We believe this is due to the demagnetization of the solid 3He layers on the aerogel strands. This system has potential for achieving extremely low temperatures in the confined fluid

Measurement of the ( p, , T) Properties for Pure Hydrocarbons at Temperatures up to 600 K and Pressures up to 200 MPa

Science.gov (United States)

Ito, T.; Nagata, Y.; Miyamoto, H.

2014-10-01

The data available for the thermodynamic properties of propane, -butane, and isobutane at temperatures above 440 K are outdated and show significant discrepancies with each other. The ambiguity associated with these data could be limiting to the development of any understanding related to the effects of mixing of these substances with other materials such as , ammonia, and non-flammable or lower-flammable HFC refrigerants. In this study, the ( p, , T) properties of propane, -butane, and isobutane were measured at temperatures ranging from (360 to 600) K and pressures ranging from (50 to 200) MPa. Precise measurements were carried out using a metal-bellows variable volumometer with a thermostatted air bath. The expanded uncertainties in the temperature, pressure, and density measurements were estimated to be 5 mK, 0.02 MPa, and 0.88 kg m ( K, MPa), 0.76 kg ( K, MPa), 0.76 kg ( K, MPa), and 2.94 kg ( K, MPa), respectively. The data obtained throughout this study were systematically compared with the calculated values derived from the available equations of state. These models agree well with the measured data at higher temperatures up to 600 K, demonstrating their suitability for an effective and precise examination of the mixing effects of potential alternative mixtures.

Preliminary thermodynamic study of regenerative Otto based cycles with zero NOx emissions operating with adiabatic and polytropic expansion

International Nuclear Information System (INIS)

Garcia, Ramon Ferreiro; Carril, Jose Carbia; Romero Gomez, Javier; Romero Gomez, Manuel

2016-01-01

Highlights: • Efficient polytropic expansion based Otto cycle. • Thermal efficiency is due to the inherent regeneration. • Low temperature combustion with zero NOx emissions. - Abstract: The aim of the paper is to demonstrate that a regenerative Otto cycle with adiabatic or polytropic expansion can achieve improved performance over traditional Otto engines, even exceeding the Carnot factor. Thus, the work deals with a novel regenerative Otto based internal combustion engine which differs from the conventional Otto thermal cycles in that the process of heat conversion into mechanical work is performed obeying a polytropic path function instead of the conventional adiabatic expansion without regeneration. Design characteristics concern the fact that combustion at constant volume is carried out undergoing large air excess so that the top combustion temperature is significantly lower than in conventional Otto cycles and consequently NOx emissions are neglected. Furthermore, during the polytropic expansion based path function, heat is absorbed by being submitted to a controlled heat flow rate, to achieve the desired polytropic expansion. The analysis of the regenerative Otto based on polytropic expansion is presented and results are compared with a regenerative Otto based on the adiabatic expansion and CF. The results show that a relevant advantage of the proposed regenerative Otto with polytropic expansion over the regenerative Otto cycle with adiabatic expansion involves performance enhancement within a wide range of combustion pressures, temperatures and regeneration capacities. Thus, thermal efficiency and specific work as function of the top combustion pressure ranges are of 71.95–58.43% and 143.5–173.6 kJ/kg respectively, when combustion pressures vary between 105 kPa and 200 kPa and CF is 60.8% (lower than the thermal efficiency). The successful results involving a compact engine structure, technically and economically viable, promises a new generation

Structure of spinel at high temperature using in-situ XANES study at the Al and Mg K-edge

Energy Technology Data Exchange (ETDEWEB)

Ligny, D de [Universite Claude Bernard Lyon 1, LPCML, 69622 Villeurbanne (France); Neuville, D R [Physique des Mineraux et Magmas, Geochimie-Cosmochimie, CNRS-IPGP, 4 place Jussieu, 75005 Paris (France); Flank, A-M; Lagarde, P, E-mail: deligny@pcml.univ-lyon1.f [Synchrotron SOLEIL, L' Orme des Merisiers, Saint Aubin, 91192 France (France)

2009-11-15

We present structural information obtained on spinel at high temperature (298-2400 K) using in situ XANES at the Mg and Al K-edge. Spinel, {sup [4]}(Al{sub x},Mg{sub 1-x}){sup [6]}(Al{sub 2-x},Mg{sub x})O{sub 4}, with increasing temperature, show a substitution of Mg by Al and Al by Mg in their respective sites. This substitution corresponds to an inversion of the Mg and Al sites. Furthermore, both experiments at the Al and Mg K-edges are in good agreement with XANES calculation made using FDMNES code.

Measuring the microwave response of superconducting Nb:STO and Ti at mK temperatures using superconducting resonators

Energy Technology Data Exchange (ETDEWEB)

Thiemann, Markus; Beutel, Manfred; Dressel, Martin; Scheffler, Marc [1. Physikalisches Institut, Universitaet Stuttgart (Germany); Fillis-Tsirakis, Evangelos; Boschker, Hans; Mannhart, Jochen [Max Planck Institute for Solid State Research, Stuttgart (Germany)

2016-07-01

Niobium doped SrTiO{sub 3} is a superconductor, with the lowest charge carrier density among all superconductors. It shows a dome in the transition temperature as a function of doping concentration with a maximum T{sub c} ∼ 0.3 K. The superconducting dome may originate from the different bands being occupied depending on the doping level. The low energy scales of the system, as indicated by the low T{sub c} are within the GHz-regime. Therefore microwave measurements are a powerful technique to reveal the electronic properties of these superconductors. We preformed microwave measurements on Nb:STO of different doping levels in a dilution refrigerator, using superconducting stripline resonators. Measurements were done in a temperature and frequency range from 40-400 mK and 1-20 GHz, covering the normal and superconducting states. For comparison we also measured the temperature dependence of the surface impedance of superconducting titanium (T{sub c} ∼ 0.5 K), which can be well described by the Mattis-Bardeen equations with a ratio (2Δ)/(k{sub B}T{sub c}) = 3.56. Therefore titanium is an ideal reference sample representing a conventional BCS-superconductor.

Flux free growth of large FeSe1/2Te1/2 superconducting single crystals by an easy high temperature melt and slow cooling method

Directory of Open Access Journals (Sweden)

P. K. Maheshwari

2015-09-01

Full Text Available We report successful growth of flux free large single crystals of superconducting FeSe1/2Te1/2 with typical dimensions of up to few cm. The AC and DC magnetic measurements revealed the superconducting transition temperature (Tc value of around 11.5K and the isothermal MH showed typical type-II superconducting behavior. The lower critical field (Hc1 being estimated by measuring the low field isothermal magnetization in superconducting regime is found to be above 200Oe at 0K. The temperature dependent electrical resistivity ρ(T  showed the Tc (onset to be 14K and the Tc(ρ = 0 at 11.5K. The electrical resistivity under various magnetic fields i.e., ρ(TH for H//ab and H//c demonstrated the difference in the width of Tc with applied field of 14Tesla to be nearly 2K, confirming the anisotropic nature of superconductivity. The upper critical and irreversibility fields at absolute zero temperature i.e., Hc2(0 and Hirr(0 being determined by the conventional one-band Werthamer–Helfand–Hohenberg (WHH equation for the criteria of normal state resistivity (ρn falling to 90% (onset, and 10% (offset is 76.9Tesla, and 37.45Tesla respectively, for H//c and 135.4Tesla, and 71.41Tesla respectively, for H//ab. The coherence length at the zero temperature is estimated to be above 20Å ´ by using the Ginsburg-Landau theory. The activation energy for the FeSe1/2Te1/2 in both directions H//c and H//ab is determined by using Thermally Activation Flux Flow (TAFF model.

Fisher zeros in the Kallen-Lehmann approach to 3D Ising model

International Nuclear Information System (INIS)

Astorino, Marco; Canfora, Fabrizio; Giribet, Gaston

2009-01-01

The distribution of the Fisher zeros in the Kallen-Lehmann approach to three-dimensional Ising model is studied. It is argued that the presence of a non-trivial angle (a cusp) in the distribution of zeros in the complex temperatures plane near the physical singularity is realized through a strong breaking of the 2D Ising self-duality. Remarkably, the realization of the cusp in the Fisher distribution ultimately leads to an improvement of the results of the Kallen-Lehmann ansatz. In fact, excellent agreement with Monte Carlo predictions both at high and at low temperatures is observed. Besides, agreement between both approaches is found for the predictions of the critical exponent α and of the universal amplitude ratio Δ=A + /A - , within the 3.5% and 7% of the Monte Carlo predictions, respectively

Phase transition in the (Li 0.5-( x/2) K 0.5-( x/2) Cs x) 2SO 4 system

Science.gov (United States)

Hamed, A. E.; El-Aziz, Y. M. Abd.; Madi, N. K.; Kassem, M. E.

1995-12-01

Phase transition in the (Li 0.5-( x/2) K 0.5-( x/2) Cs x) 2SO 4 system was studied by measuring the specific heat at constant pressure, C p, as a function of temperature in the temperature range 300-800 K. For non-zero values of X ( X = 0.2%, 0.5%, 1% and 2%) the critical behaviour of the phase transition was found to change considerably compared with that of X = 0 or pure LiKSO 4. The observed change in the phase transition with increase of Cs 2SO 4 content ( X) was accompanied by a decrease in the thermodynamic parameters: the value of the specific heat at the transition point (Δ C P) max, the transition temperature, T1, and the value of the energy of ordering. The results were interpreted within the Landau thermodynamic theory of the phase transition.

High-temperature fusion of a multielectron leviton

Science.gov (United States)

Moskalets, Michael

2018-04-01

The state of electrons injected onto the surface of the Fermi sea depends on temperature. The state is pure at zero temperature and is mixed at finite temperature. In the case of a single-electron injection, such a transformation can be detected as a decrease in shot noise with increasing temperature. In the case of a multielectron injection, the situation is subtler. The mixedness helps the development of quantum-mechanical exchange correlations between injected electrons, even if such correlations are absent at zero temperature. These correlations enhance the shot noise, which in part counteracts the reduction of noise with temperature. Moreover, at sufficiently high temperatures, the correlation contribution to noise predominates over the contribution of individual particles. As a result, in the system of N electrons, the apparent charge (which is revealed via the shot noise) is changed from e at zero temperature to N e at high temperatures. It looks like the exchange correlations glue electrons into one particle of total charge and energy. This point of view is supported by both charge noise and heat noise. Interestingly, in the macroscopic limit, N →∞ , the correlation contribution completely suppresses the effect of temperature on noise.

Estimating the Partition Function Zeros by Using the Wang-Landau Monte Carlo Algorithm

Energy Technology Data Exchange (ETDEWEB)

Kim, Seung-Yeon [Korea National University of Transportation, Chungju (Korea, Republic of)

2017-03-15

The concept of the partition function zeros is one of the most efficient methods for investigating the phase transitions and the critical phenomena in various physical systems. Estimating the partition function zeros requires information on the density of states Ω(E) as a function of the energy E. Currently, the Wang-Landau Monte Carlo algorithm is one of the best methods for calculating Ω(E). The partition function zeros in the complex temperature plane of the Ising model on an L × L square lattice (L = 10 ∼ 80) with a periodic boundary condition have been estimated by using the Wang-Landau Monte Carlo algorithm. The efficiency of the Wang-Landau Monte Carlo algorithm and the accuracies of the partition function zeros have been evaluated for three different, 5%, 10%, and 20%, flatness criteria for the histogram H(E).

Cooling of high temperature superconductors below 60 K by means of a two-stage cryogenic mixed refrigerant cascade; Kuehlung von Hochtemperatursupraleitern unterhalb von 60 K mittels einer zweistufigen Gemischkaeltekaskade

Energy Technology Data Exchange (ETDEWEB)

Kochenburger, T.M. [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Inst. fuer Technische Thermodynamik und Kaeltetechnik (ITTK); Grohmann, S. [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany). Inst. fuer Technische Thermodynamik und Kaeltetechnik (ITTK); Karlsruher Institut fuer Technologie (KIT), Eggenstein-Leopoldshafen (Germany). Inst. fuer Technische Physik (ITEP)

2015-07-01

High temperature superconductors enable the efficient transmission of electrical energy in urban and industrial networks. It is the availability of simple, reliable and at the same time efficient cooling methods prerequisite for the application of this technology. At operating temperatures 65-80 K is the cooling currently mostly implemented by liquid nitrogen, large-scale turbo-Brayton plants or batteries of regenerative cryocooler; however, all these options for applications in the range of a few kW of required cooling capacity have thermodynamic, economic and practical limitations. In addition, a further lowering the cooling temperature below 60 K is desirable to increase the current density in the superconductors. Two-stage cryogenic mixed refrigerant cascade offer the potential for a reliable and easily scalable alternative for refrigeration in this temperature range. The first stage of the considered process consists of a classic mixture refrigeration cycle to pre-cool to 120 K. The second stage operates in the low temperature range up to 55 K with a mixture of nitrogen, oxygen and neon at high pressures. This paper compares on the basis of experimental data, the performance of combustible and non-combustible mixtures in the precooling level. The applicability of various equations of state for modeling of phase behavior of mixtures is discussed. [German] Hochtemperatursupraleiter ermoeglichen den effizienten Transport elektrischer Energie in urbanen und industriellen Netzen. Dabei ist die Verfuegbarkeit von einfachen, zuverlaessigen und gleichzeitig effizienten Kuehlmethoden Voraussetzung fuer die Anwendung dieser Technologie. Bei Betriebstemperaturen von 65 - 80 K wird die Kuehlung derzeit meist durch Fluessigstickstoff, grossskalige Turbo-Brayton-Anlagen oder Batterien regenerativer Kleinkuehler realisiert; jedoch haben alle diese Optionen fuer Anwendungen im Bereich von einigen kW an erforderlicher Kaelteleistung thermodynamische, oekonomische und

Analysis of Schottky Barrier Parameters and Current Transport Properties of V/p-Type GaN Schottky Junction at Low Temperatures

Science.gov (United States)

Asha, B.; Harsha, Cirandur Sri; Padma, R.; Rajagopal Reddy, V.

2018-05-01

The electrical characteristics of a V/p-GaN Schottky junction have been investigated by current-voltage (I-V) and capacitance-voltage (C-V) characteristics under the assumption of the thermionic emission (TE) theory in the temperature range of 120-280 K with steps of 40 K. The zero-bias barrier height (ΦB0), ideality factor (n), flat-band barrier height (ΦBF) and series resistance (R S) values were evaluated and were found to be strongly temperature dependent. The results revealed that the ΦB0 values increase, whereas n, ΦFB and R S values decrease, with increasing temperature. Using the conventional Richardson plot, the mean barrier height (0.39 eV) and Richardson constant (8.10 × 10-10 Acm-2 K-2) were attained. The barrier height inhomogeneities were demonstrated by assuming a Gaussian distribution function. The interface state density (N SS) values were found to decrease with increasing temperature. The reverse leakage current mechanism of the V/p-GaN Schottky junction was found to be governed by Poole-Frenkel emission at all temperatures.

Two-color QCD with non-zero chiral chemical potential

Energy Technology Data Exchange (ETDEWEB)

Braguta, V.V. [Institute for High Energy Physics NRC “Kurchatov Institute' ,142281 Protvino (Russian Federation); Far Eastern Federal University, School of Biomedicine,690950 Vladivostok (Russian Federation); Goy, V.A. [Far Eastern Federal University, School of Natural Sciences,690950 Vladivostok (Russian Federation); Ilgenfritz, E.M. [Joint Institute for Nuclear Research,BLTP, 141980 Dubna (Russian Federation); Kotov, A.Yu. [Institute of Theoretical and Experimental Physics,117259 Moscow (Russian Federation); Molochkov, A.V. [Far Eastern Federal University, School of Biomedicine,690950 Vladivostok (Russian Federation); Müller-Preussker, M.; Petersson, B. [Humboldt-Universität zu Berlin, Institut für Physik,12489 Berlin (Germany)

2015-06-16

The phase diagram of two-color QCD with non-zero chiral chemical potential is studied by means of lattice simulation. We focus on the influence of a chiral chemical potential on the confinement/deconfinement phase transition and the breaking/restoration of chiral symmetry. The simulation is carried out with dynamical staggered fermions without rooting. The dependences of the Polyakov loop, the chiral condensate and the corresponding susceptibilities on the chiral chemical potential and the temperature are presented. The critical temperature is observed to increase with increasing chiral chemical potential.

Thermodynamic investigation of methyl salicylate/1-pentanol binary system in the temperature range from 278.15K to 303.15K

International Nuclear Information System (INIS)

Tsierkezos, Nikos G.; Molinou, Ioanna E.

2007-01-01

Densities (ρ), speeds of sound (u), isentropic compressibilities (k s ), refractive indices (n D ), and surface tensions (σ) of binary mixtures of methyl salicylate (MSL) with 1-pentanol (PEN) have been measured over the entire composition range at the temperatures of 278.15K, 288.15K, and 303.15K. The excess molar volumes (V E ), excess surface tensions (σ E ), deviations in speed of sound (Δu), deviations in isentropic compressibility (Δk s ), and deviations in molar refraction (ΔR) have been calculated. The excess thermodynamic properties V E , σ E , Δu, Δk s , and ΔR were fitted to the Redlich-Kister polynomial equation and the A k coefficients as well as the standard deviations (d) between the calculated and experimental values have been derived. The surface tension (σ) values have been further used for the calculation of the surface entropy (S S ) and the surface enthalpy (H S ) per unit surface area. The lyophobicity (β) and the surface mole fraction (x 2 S ) of the surfactant component PEN have been also derived using the extended Langmuir model. The results provide information on the molecular interactions between the unlike molecules that take place at the surface and the bulk

Reaction OH + OH studied over the 298-834 K temperature and 1-100 bar pressure ranges.

Science.gov (United States)

Sangwan, Manuvesh; Chesnokov, Evgeni N; Krasnoperov, Lev N

2012-06-21

Self-reaction of hydroxyl radicals, OH + OH → H(2)O + O (1a) and OH + OH → H(2)O(2) (1b), was studied using pulsed laser photolysis coupled to transient UV-vis absorption spectroscopy over the 298-834 K temperature and 1-100 bar pressure ranges (bath gas He). A heatable high-pressure flow reactor was employed. Hydroxyl radicals were prepared using reaction of electronically excited oxygen atoms, O((1)D), produced in photolysis of N(2)O at 193 nm, with H(2)O. The temporal behavior of OH radicals was monitored via transient absorption of light from a dc discharge in H(2)O/Ar low-pressure resonance lamp at ca. 308 nm. The absolute intensity of the photolysis light was determined by accurate in situ actinometry based on the ozone formation in the presence of molecular oxygen. The results of this study combined with the literature data indicate that the rate constant of reaction 1a, associated with the pressure independent component, decreases with temperature within the temperature range 298-414 K and increases above 555 K. The pressure dependent rate constant for (1b) was parametrized using the Troe expression as k(1b,inf) = (2.4 ± 0.6) × 10(-11)(T/300)(-0.5) cm(3) molecule(-1) s(-1), k(1b,0) = [He] (9.0 ± 2.2) × 10(-31)(T/300)(-3.5±0.5) cm(3) molecule(-1) s(-1), F(c) = 0.37.

CFD modeling of two-stage ignition in a rapid compression machine: Assessment of zero-dimensional approach

Energy Technology Data Exchange (ETDEWEB)

Mittal, Gaurav [Department of Mechanical Engineering, The University of Akron, Akron, OH 44325 (United States); Raju, Mandhapati P. [General Motor R and D Tech Center, Warren, MI 48090 (United States); Sung, Chih-Jen [Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269 (United States)

2010-07-15

In modeling rapid compression machine (RCM) experiments, zero-dimensional approach is commonly used along with an associated heat loss model. The adequacy of such approach has not been validated for hydrocarbon fuels. The existence of multi-dimensional effects inside an RCM due to the boundary layer, roll-up vortex, non-uniform heat release, and piston crevice could result in deviation from the zero-dimensional assumption, particularly for hydrocarbons exhibiting two-stage ignition and strong thermokinetic interactions. The objective of this investigation is to assess the adequacy of zero-dimensional approach in modeling RCM experiments under conditions of two-stage ignition and negative temperature coefficient (NTC) response. Computational fluid dynamics simulations are conducted for n-heptane ignition in an RCM and the validity of zero-dimensional approach is assessed through comparisons over the entire NTC region. Results show that the zero-dimensional model based on the approach of 'adiabatic volume expansion' performs very well in adequately predicting the first-stage ignition delays, although quantitative discrepancy for the prediction of the total ignition delays and pressure rise in the first-stage ignition is noted even when the roll-up vortex is suppressed and a well-defined homogeneous core is retained within an RCM. Furthermore, the discrepancy is pressure dependent and decreases as compressed pressure is increased. Also, as ignition response becomes single-stage at higher compressed temperatures, discrepancy from the zero-dimensional simulations reduces. Despite of some quantitative discrepancy, the zero-dimensional modeling approach is deemed satisfactory from the viewpoint of the ignition delay simulation. (author)

Quantal and thermal zero point motion formulae of barrier transmission probability

International Nuclear Information System (INIS)

Takigawa, N.; Alhassid, Y.; Balantekin, A.B.

1992-01-01

A Green's function method is developed to derive quantal zero point motion formulae for the barrier transmission probability in heavy ion fusion reactions corresponding to various nuclear intrinsic degrees of freedom. In order to apply to the decay of a hot nucleus, the formulae are then generalized to the case where the intrinsic degrees of freedom are in thermal equilibrium with a heat bath. A thermal zero point motion formula for vibrational coupling previously obtained through the use of influence functional methods naturally follows, and the effects of rotational coupling are found to be independent of temperature if the deformation is rigid

Studies on the zeros of Bessel functions and methods for their computation: 3. Some new works on monotonicity, convexity, and other properties

Science.gov (United States)

Kerimov, M. K.

2016-12-01

This paper continues the study of real zeros of Bessel functions begun in the previous parts of this work (see M. K. Kerimov, Comput. Math. Math. Phys. 54 (9), 1337-1388 (2014); 56 (7), 1175-1208 (2016)). Some new results regarding the monotonicity, convexity, concavity, and other properties of zeros are described. Additionally, the zeros of q-Bessel functions are investigated.

Chiral anomalies in QED and QCD at finite temperature

International Nuclear Information System (INIS)

Alvarez-Estrada, R.F.

1991-01-01

Chiral anomalies (a) for QED and QCD at finite temperature are analyzed in imaginary- and real-time formalisms. Both triangle diagrams and functional methods are used. It is found that the expressions for a in terms of finite-temperature fields are formally similar to that for the zero-temperature anomaly as a function of zero-temperature fields, thereby generalizing previous work by other authors. (author). 20 refs.; 1 fig

Net zero water

CSIR Research Space (South Africa)

Lindeque, M

2013-01-01

Full Text Available the national grid. The unfortunate situation with water is that there is no replacement technology for water. Water can be supplied from many different sources. A net zero energy development will move closer to a net zero water development by reducing...

QCD at Zero Baryon Density and the Polyakov Loop Paradox

CERN Document Server

Kratochvila, S; Forcrand, Ph. de

2006-01-01

We compare the grand canonical partition function at fixed chemical potential mu with the canonical partition function at fixed baryon number B, formally and by numerical simulations at mu=0 and B=0 with four flavours of staggered quarks. We verify that the free energy densities are equal in the thermodynamic limit, and show that they can be well described by the hadron resonance gas at T T_c. Small differences between the two ensembles, for thermodynamic observables characterising the deconfinement phase transition, vanish with increasing lattice size. These differences are solely caused by contributions of non-zero baryon density sectors, which are exponentially suppressed with increasing volume. The Polyakov loop shows a different behaviour: for all temperatures and volumes, its expectation value is exactly zero in the canonical formulation, whereas it is always non-zero in the commonly used grand-canonical formulation. We clarify this paradoxical difference, and show that the non-vanishing Polyakov loop e...

Gas phase kinetics of the OH + CH3CH2OH reaction at temperatures of the interstellar medium (T = 21-107 K).

Science.gov (United States)

Ocaña, A J; Blázquez, S; Ballesteros, B; Canosa, A; Antiñolo, M; Albaladejo, J; Jiménez, E

2018-02-21

Ethanol, CH 3 CH 2 OH, has been unveiled in the interstellar medium (ISM) by radioastronomy and it is thought to be released into the gas phase after the warm-up phase of the grain surface, where it is formed. Once in the gas phase, it can be destroyed by different reactions with atomic and radical species, such as hydroxyl (OH) radicals. The knowledge of the rate coefficients of all these processes at temperatures of the ISM is essential in the accurate interpretation of the observed abundances. In this work, we have determined the rate coefficient for the reaction of OH with CH 3 CH 2 OH (k(T)) between 21 and 107 K by employing the pulsed and continuous CRESU (Cinétique de Réaction en Ecoulement Supersonique Uniforme, which means Reaction Kinetics in a Uniform Supersonic Flow) technique. The pulsed laser photolysis technique was used for generating OH radicals, whose time evolution was monitored by laser induced fluorescence. An increase of approximately 4 times was observed for k(21 K) with respect to k(107 K). With respect to k(300 K), the OH-reactivity at 21 K is enhanced by two orders of magnitude. The obtained T-expression in the investigated temperature range is k(T) = (2.1 ± 0.5) × 10 -11 (T/300 K) -(0.71±0.10) cm 3 molecule -1 s -1 . In addition, the pressure dependence of k(T) has been investigated at several temperatures between 21 K and 90 K. No pressure dependence of k(T) was observed in the investigated ranges. This may imply that this reaction is purely bimolecular or that the high-pressure limit is reached at the lowest total pressure experimentally accessible in our system. From our results, k(T) at usual IS temperatures (∼10-100 K) is confirmed to be very fast. Typical rate coefficients can be considered to range within about 4 × 10 -11 cm 3 molecule -1 s -1 at 100 K and around 1 × 10 -10 cm 3 molecule -1 s -1 at 20 K. The extrapolation of k at the lowest temperatures of the dense molecular clouds of ISM is also discussed in this paper.

Partial molar volumes of organic solutes in water. XXIV. Selected alkane-α,ω-diols at temperatures T = 298 K to 573 K and pressures up to 30 MPa

International Nuclear Information System (INIS)

Cibulka, Ivan; Hnědkovský, Lubomír

2013-01-01

Highlights: • Standard molar volumes of three alkane-α,ω-diols (C 5 , C 8 , C 9 ) in water are presented. • Data were obtained in the range T from (298 to 573) K and p up to 30 MPa. • Dependences on carbon atom number, temperature, and pressure are analysed. -- Abstract: Density data for dilute aqueous solutions of three alkane-α,ω-diols (pentane-1,5-diol, octane-1,8-diol, nonane-1,9-diol) are presented together with standard molar volumes (partial molar volumes at infinite dilution) calculated from the experimental data. The measurements were performed at temperatures from T = 298 K up to T = 573 K. Experimental pressures were slightly above the saturation vapour pressure of water, and (15 and 30) MPa. The data were obtained using a high-temperature high-pressure flow vibrating-tube densimeter. Measured standard molar volumes were combined with data previously published for other members of the homologous series and discussed. Experimental standard molar volumes were correlated as a function of temperature and pressure using an empirical polynomial function. Dependences of standard molar volumes on temperature and pressure were analysed. Contributions of the methylene group to the standard molar volume were also evaluated and discussed

Theoretical modeling of critical temperature increase in metamaterial superconductors

Science.gov (United States)

Smolyaninov, Igor; Smolyaninova, Vera

Recent experiments have demonstrated that the metamaterial approach is capable of drastic increase of the critical temperature Tc of epsilon near zero (ENZ) metamaterial superconductors. For example, tripling of the critical temperature has been observed in Al-Al2O3 ENZ core-shell metamaterials. Here, we perform theoretical modelling of Tc increase in metamaterial superconductors based on the Maxwell-Garnett approximation of their dielectric response function. Good agreement is demonstrated between theoretical modelling and experimental results in both aluminum and tin-based metamaterials. Taking advantage of the demonstrated success of this model, the critical temperature of hypothetic niobium, MgB2 and H2S-based metamaterial superconductors is evaluated. The MgB2-based metamaterial superconductors are projected to reach the liquid nitrogen temperature range. In the case of an H2S-based metamaterial Tc appears to reach 250 K. This work was supported in part by NSF Grant DMR-1104676 and the School of Emerging Technologies at Towson University.

Description of the ππ → ππ, ππ → K anti K and K anti K → K anti K process in the framework of the N/D method

International Nuclear Information System (INIS)

Khenner, V.K.

1978-01-01

On the basis of the dispersion model the ππ → ππ, ππ → K anti K and K anti K → K anti K processes in the state with I=J=.0 are studied. The processes are considered using the N/D matrix method, permitting to solve precisely the related system of dispersion ratios for the partial amplitudes. It is shown that the discovery of the inelastic channel can be effectively taken into account by the introduction of the CDD (Castillejo-Dality-Dyson) term into the elastic scattering amplitude. It is established, that at a given ππ → ππ amplitude the transition from the complete multichannel problem, considered by the matrix method, to the linear problem leads to the solution, where all arbitrary constants are fixed in the case when zeros of the ππ → K anti K and ππ → ππ amplitudes coincide. In this case the ππ → K anti K amplitude coincides with that obtained by the Omnes-Muskhelishvili method. Other processes, where the interaction in the initial or final state is insignificant, can be also studied by such a method not resulting in the appearance of additional arbitrary parameters. The consideration of the problem of a resonance position in various channels has shown, that the matrix method does not obligatorily result in the appearance of the resonance with the permitted quantum numbers in all the interconnected channels

Electronic properties of Al/DNA/p-Si MIS diode: Application as temperature sensor

International Nuclear Information System (INIS)

Guellue, O.; Tueruet, A.

2011-01-01

Research highlights: → This work proposes that DNA molecules should be considered, among other candidates, as a potential organic thin film for metal-interface layer-semiconductor devices. → We successfully fabricated Al/DNA/p-Si device with interlayer by a simple cast method. → The temperature is found to significantly effect the electrical properties of the Al/DNA/p-Si device. → The facts: (i) that the technology of the fabrication of a Al/DNA/p-Si Schottky diode much simpler and economical than that for the Si p-n junction and (ii) the sensibility of the Al/DNA/p-Si Schottky diode as temperature sensor is 42% higher than that of a Si p-n junction, indicate that the Al/DNA/p-Si Schottky diode is a good alternative as temperature sensor. - Abstract: The current-voltage (I-V) measurements were performed in the temperature range (200-300 K) on Al/DNA/p-Si Schottky barrier type diodes. The Schottky diode shows non-ideal I-V behaviour with ideality factors n equal to 1.34 ± 0.02 and 1.70 ± 0.02 at 300 K and 200 K, respectively, and is thought to have a metal-interface layer-semiconductor (MIS) configuration. The zero-bias barrier height Φ b determined from the I-V measurements was 0.75 ± 0.01 eV at 300 K and decreases to 0.61 ± 0.01 eV at 200 K. The forward voltage-temperature (V F -T) characteristics were obtained from the I-V measurements in the temperature range 200-300 K at different activation currents (I F ) in the range 20 nA-6 μA. The V F -T characteristics were linear for three activation currents in the diode. From the V F -T characteristics at 20 nA, 100 nA and 6 μA, the values of the temperature coefficients of the forward bias voltage (dV F /dT) for the diode were determined as -2.30 mV K -1 , -2.60 mV K -1 and -3.26 mV K -1 with a standard error of 0.05 mV K -1 , respectively.

Electronic properties of Al/DNA/p-Si MIS diode: Application as temperature sensor

Energy Technology Data Exchange (ETDEWEB)

Guellue, O., E-mail: omergullu@gmail.com [Batman University, Science and Art Faculty, Department of Physics, 72060 Batman (Turkey); Osmaniye Korkut Ata University, Science and Art Faculty, Department of Physics, 80000 Osmaniye (Turkey); Tueruet, A. [Atatuerk University, Science Faculty, Department of Physics, 25240 Erzurum (Turkey)

2011-01-21

Research highlights: > This work proposes that DNA molecules should be considered, among other candidates, as a potential organic thin film for metal-interface layer-semiconductor devices. > We successfully fabricated Al/DNA/p-Si device with interlayer by a simple cast method. > The temperature is found to significantly effect the electrical properties of the Al/DNA/p-Si device. > The facts: (i) that the technology of the fabrication of a Al/DNA/p-Si Schottky diode much simpler and economical than that for the Si p-n junction and (ii) the sensibility of the Al/DNA/p-Si Schottky diode as temperature sensor is 42% higher than that of a Si p-n junction, indicate that the Al/DNA/p-Si Schottky diode is a good alternative as temperature sensor. - Abstract: The current-voltage (I-V) measurements were performed in the temperature range (200-300 K) on Al/DNA/p-Si Schottky barrier type diodes. The Schottky diode shows non-ideal I-V behaviour with ideality factors n equal to 1.34 {+-} 0.02 and 1.70 {+-} 0.02 at 300 K and 200 K, respectively, and is thought to have a metal-interface layer-semiconductor (MIS) configuration. The zero-bias barrier height {Phi}{sub b} determined from the I-V measurements was 0.75 {+-} 0.01 eV at 300 K and decreases to 0.61 {+-} 0.01 eV at 200 K. The forward voltage-temperature (V{sub F}-T) characteristics were obtained from the I-V measurements in the temperature range 200-300 K at different activation currents (I{sub F}) in the range 20 nA-6 {mu}A. The V{sub F}-T characteristics were linear for three activation currents in the diode. From the V{sub F}-T characteristics at 20 nA, 100 nA and 6 {mu}A, the values of the temperature coefficients of the forward bias voltage (dV{sub F}/dT) for the diode were determined as -2.30 mV K{sup -1}, -2.60 mV K{sup -1} and -3.26 mV K{sup -1} with a standard error of 0.05 mV K{sup -1}, respectively.

Zero emission targets as long-term global goals for climate protection

NARCIS (Netherlands)

Rogelj, Joeri; Schaeffer, M.; Meinshausen, M.; Knutti, R.

2015-01-01

Recently, assessments have robustly linked stabilization of global-mean temperature rise to the necessity of limiting the total amount of emitted carbon-dioxide (CO2). Halting global warming thus requires virtually zero annual CO2 emissions at some point. Policymakers have now incorporated this

Measurement of radiation and temperature of cathod spots in excimer laser discharge; Ekishima reza reiki hodennai ni fukumareru inkyoku kiten no kogakuteki kansoku to ondo no sokutei

Energy Technology Data Exchange (ETDEWEB)

Minamitani, Y.; Nakatani, H. [Mitsubishi Electric Corp., Tokyo (Japan)

1996-08-20

Excimer laser is used in various fields such as luminous source for steppers, annealing treatment, ablation process, nuclear fusion and so on. In this paper, the radiation timing and gas temperature of cathode spots, streamer discharges and glow discharges in KrF excimer are measured by observing the radiating spectra thereof. The following conclusions are obtained from the results of the present study. Cathode spots begin to radiate at about 20ns after the discharge initiation, then the first and second radiation peaks are observed respectively when the discharge current reversing after passing zero point and the reserved discharged current approaching zero point. Streamer discharge makes flashover between electrodes at the second radiation peak of cathode spots, while the glow discharges almost disappear when streamer discharges occurring. The temperatures of cathode spots and glow discharge as 5500K and 2600K respectively are almost constant and independent upon the discharging voltage of laser. 14 refs., 12 figs.

Zero-Based Budgeting.

Science.gov (United States)

Wichowski, Chester

1979-01-01

The zero-based budgeting approach is designed to achieve the greatest benefit with the fewest undesirable consequences. Seven basic steps make up the zero-based decision-making process: (1) identifying program goals, (2) classifying goals, (3) identifying resources, (4) reviewing consequences, (5) developing decision packages, (6) implementing a…

A real time zero-dimensional diagnostic model for the calculation of in-cylinder temperatures, HRR and nitrogen oxides in diesel engines

International Nuclear Information System (INIS)

Finesso, Roberto; Spessa, Ezio

2014-01-01

Highlights: • Real-time zero-dimensional three-zone diagnostic combustion model. • Capable of evaluating in-cylinder temperatures, HRR and NOx in DI diesel engines. • Able to be integrated in the engine ECU for control applications. • Able to be integrated in the test bed acquisition software for calibration tasks. • Tested under both steady state and fast transient conditions. - Abstract: A real-time zero-dimensional diagnostic combustion model has been developed and assessed to evaluate in-cylinder temperatures, HRR (heat release rate) and NOx (nitrogen oxides) in DI (Direct Injection) diesel engines under steady state and transient conditions. The approach requires very little computational time, that is, of the order of a few milliseconds, and is therefore suitable for real-time applications. It could, for example, be implemented in an ECU (Engine Control Unit) for the on-board diagnostics of combustion and emission formation processes, or it could be integrated in acquisition software installed on an engine test bench for indicated analysis. The model could also be used for post-processing analysis of previously acquired experimental data. The methodology is based on a three-zone thermodynamic model: the combustion chamber is divided into a fuel zone, an unburned gas zone and a stoichiometric burned gas zone, to which the energy and mass conservation equations are applied. The main novelty of the proposed method is that the equations can be solved in closed form, thus making the approach suitable for real-time applications. The evaluation of the temperature of burned gases allows the in-cylinder NOx concentration to be calculated, on the basis of prompt and Zeldovich thermal mechanisms. The procedure also takes into account the NOx level in the intake charge, and is therefore suitable for engines equipped with traditional short-route EGR (Exhaust Gas Recirculation) systems, and engines equipped with SCR (Selective Catalytic Reduction) and long

Critical Temperature of Randomly Diluted Two-Dimensional Heisenberg Ferromagnet, K2CuxZn(1-x)F4

Science.gov (United States)

Okuda, Yuichi; Tohi, Yasuto; Yamada, Isao; Haseda, Taiichiro

1980-09-01

The susceptibility of randomly diluted two-dimensional Heisenberg-like ferromagnet K2CuxZn(1-x)F4 was measured down to 50 mK, using the 3He-4He dilution refrigerator and a SQUID magnetometer. The ferromagnetic critical temperature Tc(x) was obtained for x{=}0.98, 0.94, 0.85, 0.82, 0.68, 0.60, 0.54, 0.50 and 0.42. The value of [1/Tc(1)][(d/dx)Tc(x)]x=1 was approximately 3.0. The critical temperature versus x curve exhibits a noticeable tail near the critical concentration, which may stem from the second nearest-neighbor interaction. The critical concentration xc, below which concentration there is no long range order down to T{=}0 K, was estimated to be 0.45˜0.50. The susceptibility of sample with x{=}0.42 behaves as if it obeys the Curie law down to 50 mK.

Studies of Mn0.5Cr0.5Fe2O4 ferrite by neutron diffraction at different temperatures in the range 768K ≥ T ≥ 13K

International Nuclear Information System (INIS)

Zakaria, A.K.M.; Ahmed, F.U.; Azad, A.K.; Yunus, S.M.; Asgar, M.A.; Paranjpe, S.K.; Das, A.

2002-01-01

Neutron diffraction studies of a polycrystalline manganese-chromium- ferrite with composition Mn 0.5 Cr 0.5 Fe 2 O 4 have been performed at a number of temperatures in the range 768K ≥ T ≥ 13K. The cation distributions, oxygen position parameter (u) and lattice constant (a o ) have been determined from the analysis of the higher angle neutron diffraction data. The temperature response of the lattice constant has also been investigated and a slight anomalous expansion has been found around the magnetic transition temperature. Sublattice as well as net ferrimagnetic moments of the specimen have been found out from the analysis of the neutron diffraction data at different temperatures. A randomly canted ordering of spins has been observed in the B sublattice, while the A sublattice moments appear to exhibit collinear Neel type ordering at all temperatures. (author)

Vitrification of Simulated Fernald K-65 Silo Waste at Low Temperature

International Nuclear Information System (INIS)

Jantzen, C.M.; Pickett, J.B.

1998-01-01

Vitrification is the technology that has been chosen to solidify approximately 15,500 tons of geologic mill tailings at the Fernald Environmental Management Project (FEMP) in Fernald, Ohio. The geologic mill tailings are residues from the processing of pitchlende ore during 1949-1958. These waste residues are contained in silos in Operable Unit 4 (OU4) at the FEMP facility. Operable Unit 4 is one of five operable units at the FEMP. Operating Unit 4 consists of four concrete storage silos and their contents. Silos 1 and 2 contain K-65 mill tailing residues and a bentonite cap, Silo 3 contains non-radioactive metal oxides, and Silo 4 is empty. The K-65 residues contain radium, uranium, uranium daughter products, and heavy metals such as lead and barium.The K-65 waste leaches lead at greater than 100 times the allowable Environmental Protection Agency (EPA) Resource, Conservation, and Recovery Act (RCRA) concentration limits when tested by the Toxic Characteristic Leaching Procedure (TCLP). Vitrification was chosen by FEMP as the preferred technology for the Silos 1, 2, 3 wastes because the final waste form met the following criteria: controls radon emanation, eliminates the potential for hazardous or radioactive constituents to migrate to the aquifer below FEMP, controls the spread of radioactive particulates, reduces leachability of metals and radiological constituents, reduces volume of final wasteform for disposal, silo waste composition is favorable to vitrification, will meet current and proposed RCRA TCLP leaching criteria Glasses that melt at 1350 degrees C were developed by Pacific Northwest National Laboratory (PNNL) and glasses that melt between 1150-1350 degrees C were developed by the Vitreous State Laboratory (VSL) for the K-65 silo wastes. Both crucible studies and pilot scale vitrification studies were conducted by PNNL and VSL. Subsequently, a Vitrification Pilot Plant (VPP) was constructed at FEMP capable of operating at temperatures up to 1450

Thermodynamic investigation of methyl salicylate/1-pentanol binary system in the temperature range from 278.15K to 303.15K

Energy Technology Data Exchange (ETDEWEB)

Tsierkezos, Nikos G. [Institut fuer Chemie, Humboldt-Universitaet zu Berlin, Brook-Taylor-Strasse 2, D-12489 Berlin (Germany)]. E-mail: tsierkezos@chemie.hu-berlin.de; Molinou, Ioanna E. [Physical Chemistry Laboratory, Department of Chemistry, University of Athens, Panepistimiopolis, Athens 15771 (Greece)]. E-mail: imolinou@chem.uoa.gr

2007-08-15

Densities ({rho}), speeds of sound (u), isentropic compressibilities (k{sub s}), refractive indices (n{sub D}), and surface tensions ({sigma}) of binary mixtures of methyl salicylate (MSL) with 1-pentanol (PEN) have been measured over the entire composition range at the temperatures of 278.15K, 288.15K, and 303.15K. The excess molar volumes (V{sup E}), excess surface tensions ({sigma}{sup E}), deviations in speed of sound ({delta}u), deviations in isentropic compressibility ({delta}k{sub s}), and deviations in molar refraction ({delta}R) have been calculated. The excess thermodynamic properties V{sup E}, {sigma}{sup E}, {delta}u, {delta}k{sub s}, and {delta}R were fitted to the Redlich-Kister polynomial equation and the A{sub k} coefficients as well as the standard deviations (d) between the calculated and experimental values have been derived. The surface tension ({sigma}) values have been further used for the calculation of the surface entropy (S{sup S}) and the surface enthalpy (H{sup S}) per unit surface area. The lyophobicity ({beta}) and the surface mole fraction (x{sub 2}{sup S}) of the surfactant component PEN have been also derived using the extended Langmuir model. The results provide information on the molecular interactions between the unlike molecules that take place at the surface and the bulk.

Zero-truncated negative binomial - Erlang distribution

Science.gov (United States)

Bodhisuwan, Winai; Pudprommarat, Chookait; Bodhisuwan, Rujira; Saothayanun, Luckhana

2017-11-01

The zero-truncated negative binomial-Erlang distribution is introduced. It is developed from negative binomial-Erlang distribution. In this work, the probability mass function is derived and some properties are included. The parameters of the zero-truncated negative binomial-Erlang distribution are estimated by using the maximum likelihood estimation. Finally, the proposed distribution is applied to real data, the number of methamphetamine in the Bangkok, Thailand. Based on the results, it shows that the zero-truncated negative binomial-Erlang distribution provided a better fit than the zero-truncated Poisson, zero-truncated negative binomial, zero-truncated generalized negative-binomial and zero-truncated Poisson-Lindley distributions for this data.

Johnson Noise Thermometry in the range 505 K to 933 K

Science.gov (United States)

Tew, Weston; Labenski, John; Nam, Sae Woo; Benz, Samuel; Dresselhaus, Paul; Martinis, John

2006-03-01

The International Temperature Scale of 1990 (ITS-90) is an artifact-based temperature scale, T90, designed to approximate thermodynamic temperature T. The thermodynamic errors of the ITS-90, characterized as the value of T-T90, only recently have been quantified by primary thermodynamic methods. Johnson Noise Thermometry (JNT) is a primary method which can be applied over wide temperature ranges, and NIST is currently using JNT to determine T-T90 in the range 505 K to 933 K, overlapping both acoustic gas-based and radiation-based thermometry. Advances in digital electronics have now made the computationally intensive processing required for JNT viable using noise voltage correlation in the frequency domain. We have also optimized the design of the 5-wire JNT temperature probes to minimize electromagnetic interference and transmission line effects. Statistical uncertainties under 50 μK/K are achievable using relatively modest bandwidths of ˜100 kHz. The NIST JNT system will provide critical data for T-T90 linking together the highly accurate acoustic gas-based data at lower temperatures with the higher-temperature radiation-based data, forming the basis for a new International Temperature Scale with greatly improved thermodynamic accuracy.

Micromechanical properties of C70 single crystals in the temperature range 77-350 K

International Nuclear Information System (INIS)

Lubenets, S.V.; Natsik, V.D.; Fomenko, L.S.; Rusakova, A.V.; Natsik, V.D.; Osip'yan, Yu.A.; Orlov, V.I.; Sidorov, N.S.; Izotov, A.N.

2012-01-01

Hexagonal single crystals of C 70 up to a size down to 1-2 mm were grown which allowed for the first time to investigate their low-temperature mechanical properties. Morphology, microplasticity anisotropy and the temperature dependence of Vickers microhardness HV (T) of the C 70 crystals in the temperature range 77-350 K involving all known phase transitions have been studied with the aid of optical microscopy and microindentation. The association of the features of HV (T) dependence with orientation phase transformations has been analyzed. It is suggested that anisotropy of microplasticity in the C 70 crystals correlates with the active slip systems.

Advanced Energy Design Guide K-12: Next Generation of School Design and Operation

Energy Technology Data Exchange (ETDEWEB)

Torcellini, Paul A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Pless, Shanti [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2018-01-01

Driven by energy efficiency advances and renewable energy cost reductions, zero energy buildings are popping up all around the country. Although zero energy represents a bold paradigm shift - from buildings that consume energy to buildings that produce enough energy to meet their energy needs on an annual basis - it isn't a sudden shift. Zero energy buildings are the result of steady, incremental progress by researchers and building professionals working together to improve building energy performance. ASHRAE is taking the lead by publishing - in partnership with the American Institute of Architects (AIA), the Illuminating Engineering Society (IES), the U.S. Green Building Council (USGBC), and the U.S. Department of Energy (DOE) - a new series of advanced energy design guides (AEDGs) focused on zero energy buildings. The recently completed Advanced Energy Design Guide for K-12 School Buildings: Achieving Zero Energy (K-12 ZE AEDG) is the first in this series.

Densities and volumetric properties of a (xylene + dimethyl sulfoxide) at temperature from (293.15 to 353.15) K

International Nuclear Information System (INIS)

Wang Haijun; Liu Wei; Huang Jihou

2004-01-01

The densities of (o-xylene, or m-xylene, or p-xylene + dimethyl sulfoxide) were measured at temperatures (293.15, 303.15, 313.15, 323.15, 333.15, 343.15, 353.15) K and atmospheric pressure by means of a vibrating-tube densimeter. The excess molar volume V m E calculated from the density data provide the temperature dependence of V m E in the temperature range of (293.15 to 353.15) K. The V m E results were correlated using the fourth-order Redlich-Kister equation, with the maximum likelihood principle being applied for the determination of the adjustable parameters. Also we have calculated partial molar volume and excess partial molar volumes of two components. It was found that the V m E in the systems studied increase with rising temperature

Deposition of superconducting (Cu, C)-Ba-O films by pulsed laser deposition at moderate temperature

International Nuclear Information System (INIS)

Yamamoto, Tetsuro; Kikunaga, Kazuya; Obara, Kozo; Terada, Norio; Kikuchi, Naoto; Tanaka, Yasumoto; Tokiwa, Kazuyasu; Watanabe, Tsuneo; Sundaresan, Athinarayanan; Shipra

2007-01-01

Superconducting (Cu, C)-Ba-O thin films have been epitaxially grown on (100) SrTiO 3 at a low growth temperature of 500-600 deg. C by pulsed laser deposition. The dependences of their crystallinity and transport properties on preparation conditions have been investigated in order to clarify the dominant parameters for carbon incorporation and the emergence of superconductivity. It has been revealed that the CO 3 content in the films increases with increasing both the parameters of partial pressure of CO 2 during film growth and those of growth rate and enhancement of superconducting properties. The present study has also revealed that the structural and superconducting properties of the (Cu, C)-Ba-O films are seriously deteriorated by the irradiation of energetic particles during deposition. Suppression of the radiation damage is another key for a high and uniform superconducting transition. By these optimizations, a superconducting onset temperature above 50 K and a zero-resistance temperature above 40 K have been realized

Corrosion of silicon nitride in high temperature alkaline solutions

Energy Technology Data Exchange (ETDEWEB)

Qiu, Liyan, E-mail: liyan.qiu@cnl.ca; Guzonas, Dave A.; Qian, Jing

2016-08-01

The corrosion of silicon nitride (Si{sub 3}N{sub 4}) in alkaline solutions was studied at temperatures from 60 to 300 °C. Si{sub 3}N{sub 4} experienced significant corrosion above 100 °C. The release rates of silicon and nitrogen follow zero order reaction kinetics and increase with increasing temperature. The molar ratio of dissolved silicon and nitrogen species in the high temperature solutions is the same as that in the solid phase (congruent dissolution). The activation energy for silicon and nitrogen release rates is 75 kJ/mol which agrees well with that of silica dissolution. At 300 °C, the release of aluminum is observed and follows first order reaction kinetics while other minor constituents including Ti and Y are highly enriched on the corrosion films due to the low solubility of their oxides.

Solid strong base K-Pt/NaY zeolite nano-catalytic system for completed elimination of formaldehyde at room temperature

Science.gov (United States)

Song, Shaoqing; Wu, Xi; Lu, Changhai; Wen, Meicheng; Le, Zhanggao; Jiang, Shujuan

2018-06-01

Solid strong base nano-catalytic system of K-modification NaY zeolite supported 0.08% Pt (K-Pt/NaY) were constructed for eliminating HCHO at room temperature. In the catalytic process, activation energy over K-Pt/NaY nano-catalytic system was greatly decreased along with the enhanced reaction rate. Characterization and catalytic tests revealed the surface electron structure of K-Pt/NaY was improved, as reflected by the enhanced HCHO adsorption capability, high sbnd OH concentration, and low-temperature reducibility. Therefore, the optimal K-Pt/NaY showed high catalytic efficiency and strong H2O tolerance for HCHO elimination by directly promoting the reaction between active sbnd OH and formate species. These results may suggest a new way for probing the advanced solid strong base nano-catalytic system for the catalytic elimination of indoor HCHO.

Structural investigation on K3Gd5(PO4)6 in between 20 K to 1073 K

International Nuclear Information System (INIS)

Bevara, Samatha; Achary, S.N.; Tyagi, A.K.; Mishra, K.K.; Ravindran, T.R.; Sinha, A.K.; Sastry, P.U.

2016-01-01

Evolution of crystal structure of K 3 Gd 5 (PO 4 ) 6 in the temperature range from 20 K to 1073 K, as observed from combined variable temperature X-ray diffraction (using both synchrotron source and Cu K α lab source) and Raman spectroscopic studies is communicated in the manuscript. The title compound has an open tunnel containing three dimensional structure built by periodic arrangements of (Gd 5 (PO 4 ) 6 ) 3- ions which in turn are formed by PO 4 tetrahedra and GdO n (n = 8 and 9) polyhedra and these tunnels are occupied by K + ions. The XRD patterns in the entire temperature range of study indicated no change in the crystal structural, which is also supported by differential thermal analyses and Raman spectroscopy. Average axial thermal expansion coefficients between 20K and 1073 K are : α a =10.6 x 10 -6 K -1 , α b = 5.5 x 10 -6 K -1 and α c = 16.4 X 10.6 -6 K -1 . (author)

Spin valve-like magnetic tunnel diode exhibiting giant positive junction magnetoresistance at low temperature in Co2MnSi/SiO2/p-Si heterostructure

Science.gov (United States)

Maji, Nilay; Kar, Uddipta; Nath, T. K.

2018-02-01

The rectifying magnetic tunnel diode has been fabricated by growing Co2MnSi (CMS) Heusler alloy film carefully on a properly cleaned p-Si (100) substrate with the help of electron beam physical vapor deposition technique and its structural, electrical and magnetic properties have been experimentally investigated in details. The electronic- and magneto-transport properties at various isothermal conditions have been studied in the temperature regime of 78-300 K. The current-voltage ( I- V) characteristics of the junction show an excellent rectifying magnetic tunnel diode-like behavior throughout that temperature regime. The current ( I) across the junction has been found to decrease with the application of a magnetic field parallel to the plane of the CMS film clearly indicating positive junction magnetoresistance (JMR) of the heterostructure. When forward dc bias is applied to the heterostructure, the I- V characteristics are highly influenced on turning on the field B = 0.5 T at 78 K, and the forward current reduces abruptly (99.2% current reduction at 3 V) which is nearly equal to the order of the magnitude of the current observed in the reverse bias. Hence, our Co2MnSi/SiO2/p-Si heterostructure can perform in off ( I off)/on ( I on) states with the application of non-zero/zero magnetic field like a spin valve at low temperature (78 K).

Temperature stability of static and dynamic properties of 1.55 µm quantum dot lasers.

Science.gov (United States)

Abdollahinia, A; Banyoudeh, S; Rippien, A; Schnabel, F; Eyal, O; Cestier, I; Kalifa, I; Mentovich, E; Eisenstein, G; Reithmaier, J P

2018-03-05

Static and dynamic properties of InP-based 1.55 µm quantum dot (QD) lasers were investigated. Due to the reduced size inhomogeneity and a high dot density of the newest generation of 1.55 µm QD gain materials, ridge waveguide lasers (RWG) exhibit improved temperature stability and record-high modulation characteristics. Detailed results are shown for the temperature dependence of static properties including threshold current, voltage-current characteristics, external differential efficiency and emission wavelength. Similarly, small and large signal modulations were found to have only minor dependences on temperature. Moreover, we show the impact of the active region design and the cavity length on the temperature stability. Measurements were performed in pulsed and continuous wave operation. High characteristic temperatures for the threshold current were obtained with T 0 values of 144 K (15 - 60 °C), 101 K (60 - 110 °C) and 70 K up to 180 °C for a 900-µm-long RWG laser comprising 8 QD layers. The slope efficiency in these lasers is nearly independent of temperature showing a T 1 value of more than 900 K up to 110 °C. Due to the high modal gain, lasers with a cavity length of 340 µm reached new record modulation bandwidths of 17.5 GHz at 20 °C and 9 GHz at 80 °C, respectively. These lasers were modulated at 26 GBit/s in the non-return to zero format at 80 °C and at 25 GBaud using a four-level pulse amplitude format at 21 °C.

Low-temperature synthesis and structural properties of ferroelectric K 3WO 3F 3 elpasolite

Science.gov (United States)

Atuchin, V. V.; Gavrilova, T. A.; Kesler, V. G.; Molokeev, M. S.; Aleksandrov, K. S.

2010-06-01

Low-temperature ferroelectric G2 polymorph of K 3WO 3F 3 has been prepared by chemical synthesis. Structural and chemical properties of the final product have been evaluated with X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Structure parameters of G2-K 3WO 3F 3 are refined by the Rietveld method from XRD data measured at room temperature (space group Cm, Z = 2, a = 8.7350(3) Å, b = 8.6808(5) Å, c = 6.1581(3) Å, β = 135.124(3) Å, V = 329.46(3) Å 3; RB = 2.47%). Partial ordering of oxygen and fluorine atoms has been found over anion positions. Mechanism of ferroelectric phase transition in A 2BMO 3F 3 oxyfluorides is discussed.

Cosmiclike domain walls in superfluid 3He-B: Instantons and diabolical points in (k,r) space

International Nuclear Information System (INIS)

Salomaa, M.M.; Volovik, G.E.

1988-01-01

The possible planar superfluid B-B boundaries between inequivalent B-phase vacua are considered; such B-B interfaces provide an analogy with the cosmic domain walls that are believed to have precipitated in the phase transitions of the early Universe. Several of them display nontrivial structure in (k,r) space (i.e., the union of the momentum and real spaces). Such a wall represents an instanton connecting two B-phase vacua with different k-space topology. The transition between the vacua occurs through the formation of a pointlike defect either in the (k,r) space, or in the (k,t) space. These defects are so-called diabolical points of codimension 4, at which the fermionic energy tends to zero, thus providing the fermionic zero modes. Such points are new examples (within condensed-matter physics) of the peculiar diabolical points, which are characterized by the occurrence of a contact between the different branches of the quasiparticle spectra; in the present case, the branches of particles and holes, respectively. These points are here discussed for the case of the superfluid phases of liquid 3 He in close analogy with the quantum field theory of fermions interacting with classical bosonic fields. The cosmiclike domain walls in superfluid 3 He-B are observable in principle; in particular, the motion of the superfluid A-B interface is governed at low temperatures by the periodical emission of these topological excitation planes

Fine structures on zero-field steps in low-loss Josephson tunnel junctions

DEFF Research Database (Denmark)

Monaco, Roberto; Barbara, Paola; Mygind, Jesper

1993-01-01

The first zero-field step in the current-voltage characteristic of intermediate-length, high-quality, low-loss Nb/Al-AlOx/Nb Josephson tunnel junctions has been carefully investigated as a function of temperature. When decreasing the temperature, a number of structures develop in the form...... of regular and slightly hysteretic steps whose voltage position depends on the junction temperature and length. This phenomenon is interesting for the study of nonlinear dynamics and for application of long Josephson tunnel junctions as microwave and millimeter-wavelength oscillators....

Conventional superconductivity at 203 K at high pressures

Energy Technology Data Exchange (ETDEWEB)

Drozdov, Alexander; Eremets, Mikhail; Troyan, Ivan [Max-Planck-Institut fuer Chemie, Hahn-Meitner-Weg 1, 55128 Mainz (Germany); Ksenofontov, Vadim; Shylin, Sergii [Institut fuer Anorganische Chemie und Analytische Chemie, Johannes Gutenberg-Universitet Mainz, Staudingerweg 9, 55099 Mainz (Germany)

2016-07-01

A search for high, room temperature conventional superconductivity is promising as the Bardeen-Cooper-Schrieffer (BCS) theory in the Eliashberg formulation puts no apparent limits on T{sub c}. Materials with light elements are especially favorable as they provide high frequencies in the phonon spectrum. However only a moderately high T{sub c} = 39 K has been found in this search in MgB{sub 2}. We systematically studied metallic hydrogen and covalent hydrogen dominant compounds and found the record T{sub c} of 203 K at pressure 140 GPa in sulfur hydride. We proved occurrence of superconductivity by the sharp drop of the resistivity to zero; the decrease of T{sub c} with magnetic field; the pronounce isotope shift of T{sub c} in D{sub 2}S which evidences of a major role of phonons in the superconductivity; and the magnetic susceptibility measurements. The X-ray diffraction data confirmed that the superconductive phase has the predicted bcc structure. This phase can be considered as an atomic hydrogen superconductor stabilized by sulfur.

Temperature stability of c-axis oriented LiNbO3/SiO2/Si thin film layered structures

International Nuclear Information System (INIS)

Tomar, Monika; Gupta, Vinay; Mansingh, Abhai; Sreenivas, K.

2001-01-01

Theoretical calculations have been performed for the temperature stability of the c-axis oriented LiNbO 3 thin film layered structures on passivated silicon (SiO 2 /Si) substrate with and without a non-piezoelectric SiO 2 overlayer. The phase velocity, electromechanical coupling coefficient and temperature coefficient of delay (TCD) have been calculated. The thicknesses of various layers have been determined for optimum SAW performance with zero TCD. The presence of a non-piezoelectric SiO 2 overlayer on LiNbO 3 film is found to significantly enhance the coupling coefficient. The optimized results reveal that a high coupling coefficient of K 2 =3.45% and a zero TCD can be obtained in the SiO 2 /LiNbO 3 /SiO 2 /Si structure with a 0.235λ thick LiNbO 3 layer sandwiched between 0.1λ thick SiO 2 layers. (author)

The density of molten indium at temperatures up to 600 K

International Nuclear Information System (INIS)

Alchagirov, B.B.; Khatsukov, A.M.; Mozgovoj, A.G.

2004-01-01

The liquid indium density measurement is carried out through the pycnometric method within the temperature range of 434-600 K both by heating and cooling. The totality of the obtained results was processed through the approximating equation. The root-mean-square deviation of the experimental data from the approximating equation does not exceed ±0.01%. The high accuracy of the obtained results is noted. The deviation of the existing data on the liquid indium density from the approximating equation is shown graphically [ru

Maglev system concept using 20-K high-temperature superconductors and hyperconductors

Science.gov (United States)

Hull, J. R.; He, Jianliang

A magnetically levitated high-speed ground transportation concept is proposed that uses high-temperature superconductors or hyperconductors, cooled by liquid hydrogen at 20 K, to provide levitation. An on-board hydrogen-powered turbine/generator provides electricity for propulsion by linear induction motors. The liquid hydrogen is used to cool the superconductors and the windings of the generator and motors before combusting in the turbine. The principal advantage of this system is the potential to greatly reduce the cost of the guideway, which is completely passive.

Borehole temperatures reveal a changed energy budget at Mill Island, East Antarctica, over recent decades

Directory of Open Access Journals (Sweden)

J. L. Roberts

2013-02-01

Full Text Available A borehole temperature record from the Mill Island (East Antarctica icecap reveals a large surface warming signal manifested as a 0.75 K temperature difference over the approximate 100 m depth in the zone of zero annual amplitude below the seasonally varying zone. The temperature profile shows a break in gradient around 49 m depth, which we model with inverse numerical simulations, indicating that surface warming started around the austral summer of 1980/81 AD ±5 yr. This warming of approximately 0.37 K per decade is consistent with trends seen in both instrumental and other reconstructions for Antarctica and, therefore, suggests that regional- rather than local-scale processes are largely responsible. Alteration of the surface energy budget arising from changes in radiation balances due to local cloud, the amount of liquid deposition and local air temperatures associated with altered air/sea exchanges also potentially plays a role at this location due to the proximity of the Shackleton Ice Shelf and sea-ice zone.

Energy Analysis at a Near Zero Energy Building. A Case-Study in Spain

Directory of Open Access Journals (Sweden)

Javier M. Rey-Hernández

2018-04-01

Full Text Available This paper develops an energy analysis for an existing near Zero Energy (nZEB and Zero Carbon Emissions building called LUCIA, located at the university campus in Valladolid (Spain. It is designed to supply electricity, cooling and heating needs through solar energy (Photovoltaic Systems, PV, biomass and an Earth–Air Heat Exchanger (EAHE, besides a Combined Heat Power (CHP. It is currently among the top three buildings with the highest LEED certification in the World. The building model is simulated with DesignBuilder version 5. The results of the energy analysis illustrate the heating, cooling and lighting consumptions expected, besides other demands and energy uses. From this data, we carried out an energy balance of the nZEB, which will help to plan preventive actions when compared to the actual energy consumptions, improving the management and control of both the building and its systems. The primary energy indicator obtained is 67 kWh/m2 a year, and 121 kWh/m2 a year for renewable energy generation, with respect to 55 kWh/m2 and 45 kWh/m2 set as reference in Europe. The Renewable Energy Ratio (RER is 0.66. These indicators become a useful tool for the energy analysis of the nZEB according to the requirements in the European regulations and for its comparison with further nZEB.

Gas phase kinetics of the OH + CH3CH2OH reaction at temperatures of the interstellar medium (T = 21-10^7 K)

Science.gov (United States)

Ocaña, A. J.; Blázquez, S.; Ballesteros, B.; Canosa, A.; Antiñolo, M.; Albaladejoab, J.; Jiménez, E.

2018-02-01

Ethanol, CH3CH2OH, has been unveiled in the interstellar medium (ISM) by radioastronomy and it is thought to be released into the gas phase after the warm-up phase of the grain surface, where it is formed. Once in the gas phase, it can be destroyed by different reactions with atomic and radical species, such as hydroxyl (OH) radicals. The knowledge of the rate coefficients of all these processes at temperatures of the ISM is essential in the accurate interpretation of the observed abundances. In this work, we have determined the rate coefficient for the reaction of OH with CH3CH2OH (k(T)) between 21 and 10^7 K by employing the pulsed and continuous CRESU (Cinétique de Réaction en Ecoulement Supersonique Uniforme, which means Reaction Kinetics in a Uniform Supersonic Flow) technique. The pulsed laser photolysis technique was used for generating OH radicals, whose time evolution was monitored by laser induced fluorescence. An increase of approximately 4 times was observed for k(21 K) with respect to k(10^7 K). With respect to k(300 K), the OH-reactivity at 21 K is enhanced by two orders of magnitude. The obtained T-expression in the investigated temperature range is k(T) = (2.1 ± 0.5) × 10^-11 (T/300 K)-(0.71±0.10) cm^3 molecule^-1 s^-1. In addition, the pressure dependence of k(T) has been investigated at several temperatures between 21 K and 90 K. No pressure dependence of k(T) was observed in the investigated ranges. This may imply that this reaction is purely bimolecular or that the high-pressure limit is reached at the lowest total pressure experimentally accessible in our system. From our results, k(T) at usual IS temperatures (˜10-100 K) is confirmed to be very fast. Typical rate coefficients can be considered to range within about 4 × 10^-11 cm^3 molecule^-1 s^-1 at 100 K and around 1 × 10^-10 cm^3 molecule^-1 s^-1 at 20 K. The extrapolation of k at the lowest temperatures of the dense molecular clouds of ISM is also discussed in this paper.

dK/da effects on the SCC growth rates of nickel base alloys in high-temperature water

Science.gov (United States)

Chen, Kai; Wang, Jiamei; Du, Donghai; Andresen, Peter L.; Zhang, Lefu

2018-05-01

The effect of dK/da on crack growth behavior of nickel base alloys has been studied by conducting stress corrosion cracking tests under positive and negative dK/da loading conditions on Alloys 690, 600 and X-750 in high temperature water. Results indicate that positive dK/da accelerates the SCC growth rates, and the accelerating effect increases with dK/da and the initial CGR. The FRI model was found to underestimate the dK/da effect by ∼100X, especially for strain hardening materials, and this underscores the need for improved insight and models for crack tip strain rate. The effect of crack tip strain rate and dK/dt in particular can explain the dK/da accelerating effect.

Statistical physics when the minimum temperature is not absolute zero

Science.gov (United States)

Chung, Won Sang; Hassanabadi, Hassan

2018-04-01

In this paper, the nonzero minimum temperature is considered based on the third law of thermodynamics and existence of the minimal momentum. From the assumption of nonzero positive minimum temperature in nature, we deform the definitions of some thermodynamical quantities and investigate nonzero minimum temperature correction to the well-known thermodynamical problems.

Melting-pressure and density equations of 3He at temperatures from 0.001 to 30 K

International Nuclear Information System (INIS)

Huang Yonghua; Chen Guobang

2005-01-01

Nonsegmented equations for melting pressure and density at temperatures from 0.001 K to 30 K have been developed to fit the reference data. The maximum and average deviations between the melting pressure equation and the totaling 298 reference data are 2.17% and 0.218%, respectively. For the density equations, the average deviations are 0.236% for the liquid side and 0.218% for the solid side. Both the melting pressure curve and melting density curves predicted by the submitted equations approach their minimums at about 0.315 K

A study of phase separation in peptide-loaded HPMC films using T(zero)-modulated temperature DSC, atomic force microscopy, and scanning electron microscopy.

Science.gov (United States)

Hussain, Samana; Grandy, David B; Reading, Mike; Craig, Duncan Q M

2004-07-01

Despite the widespread use of drug-loaded polymeric systems, there is still considerable uncertainty with regard to the nature of the distribution of the drug within the polymer matrix. The aim of this investigation was to develop thermal and microscopic techniques whereby the miscibility and spatial distribution of a model peptide, cyclosporin A (CyA), in hydroxypropyl methylcellulose (HPMC) films may be studied. The new technique of T(zero)-modulated temperature differential scanning calorimetry (T(zero) MTDSC), scanning electron microscopy (SEM), and pulse force mode atomic force microscopy (PFM-AFM) were used in conjunction to study films prepared using a solvent evaporation process, with a solvent extraction study performed to elucidate the nature of the observed phases. T(zero) MTDSC studies showed glass transitions for both the HPMC and CycA, with the T(g) for the HPMC and CycA seen for the mixed systems. SEM showed two spherical phases of differing electron density. PFM-AFM also showed spheres of differing adhesion that increased in size on addition of drug. Pixel intensity analysis indicated that the smaller spheres corresponded to CycA. Exposure of the films to dichloromethane, in which CycA is soluble but HPMC is not, resulted in the presence of voids that corresponded well to the spheres suggested to correspond to the drug. It was concluded that the system had undergone extensive or complete phase separation, and that the thermal and microscopic techniques outlined above are an effective means by which this issue may be studied. Copyright 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 93:1672-1681, 2004

X-ray diffraction studies on K3Gd5 (PO4) 6 between 20K to 1073 K

International Nuclear Information System (INIS)

Bevara, Samatha; Achary, S.N.; Tyagi, A.K.; Sinha, A.K.; Sastry, P.U.

2016-01-01

Complex inorganic phosphates have been of interest due to their diversified crystal chemistry depending on composition, preparation condition as well as external parameters like temperature and pressure. In addition varieties of complex phosphates have been considered as potential host matrices for immobilization of radioactive elements as well as for selective separation of ions from high level nuclear waste or heavy metal ion pollutants from environment. Temperature and/or pressure induced structural variations are often noticed in such type complex phosphates. In K 2 O-Gd 2 O 3 -P 2 O 5 , a novel complex phosphate with K 3 Gd 5 (PO 4 ) 6 has been reported recently. In order to study the effect of temperature on crystal structure of K 3 Gd 5 (PO 4 ) 6 variable temperature XRD studies between 20 K to 1073 K were carried out and the results are presented herein

Heavy-traffic analysis of k-limited polling systems

NARCIS (Netherlands)

Boon, M.A.A.; Winands, E.M.M.

2013-01-01

In this paper we study a two-queue polling model with zero switch-over times and k-limited service (serve at most k_i customers during one visit period to queue i, i = 1,2) in each queue. The arrival processes at the two queues are Poisson, and the service times are exponentially distributed. By

Heavy-traffic analysis of k-limited polling systems

NARCIS (Netherlands)

Boon, M.A.A.; Winands, E.M.M.

2014-01-01

In this paper, we study a two-queue polling model with zero switchover times and k-limited service (serve at most k_i customers during one visit period to queue i, i=1, 2) in each queue. The arrival processes at the two queues are Poisson, and the service times are exponentially distributed. By

Thermoeconomic analysis of a novel zero-CO2-emission high-efficiency power cycle using LNG coldness

International Nuclear Information System (INIS)

Liu, Meng; Lior, Noam; Zhang, Na; Han, Wei

2009-01-01

This paper presents a thermoeconomic analysis aimed at the optimization of a novel zero-CO 2 and other emissions and high-efficiency power and refrigeration cogeneration system, COOLCEP-S (Patent pending), which uses the liquefied natural gas (LNG) coldness during its revaporization. It was predicted that at the turbine inlet temperature (TIT) of 900 C, the energy efficiency of the COOLCEP-S system reaches 59%. The thermoeconomic analysis determines the specific cost, the cost of electricity, the system payback period and the total net revenue. The optimization started by performing a thermodynamic sensitivity analysis, which has shown that for a fixed TIT and pressure ratio, the pinch point temperature difference in the recuperator, (delta)T p1 , and that in the condenser, (delta)T p2 are the most significant unconstrained variables to have a significant effect on the thermal performance of novel cycle. The payback period of this novel cycle (with fixed net power output of 20 MW and plant life of 40 years) was ∝5.9 years at most, and would be reduced to ∝3.1 years at most when there is a market for the refrigeration byproduct. The capital investment cost of the economically optimized plant is estimated to be about 1000 /kWe, and the cost of electricity is estimated to be 0.34-0.37 CNY/kWh (∝0.04 USD/kWh). These values are much lower than those of conventional coal power plants being installed at this time in China, which, in contrast to COOLCEP-S, do produce CO 2 emissions at that. (author)

Corium Oxidation at Temperatures Above 2000 K

International Nuclear Information System (INIS)

Hagrman, Donald L.; Rempe, Joy L.

2001-01-01

A mechanistic model, based on a quasi-equilibrium analysis of oxidation reactions, is proposed for predicting high-temperature corium oxidation. The analysis suggests that oxide forming on the surface of corium containing uranium, zirconium, and iron is similar to the oxides formed on zirconium and uranium as long as there is a small percentage of unoxidized zirconium or uranium in the metallic phase. This is because of the higher affinity of zirconium and uranium for oxygen. Hence, oxidation rates and heat production rates are similar to (U,Zr) compounds until nearly all the uranium and zirconium in the corium oxidizes. Oxidation rates after this point are predicted to be similar to those implied by the oxide thickness present when the forming oxide ceases to be protective, and heat generation rates should be similar to those implied by iron oxidation, i.e., ∼4% of the zirconium oxidation heating rate.The maximum atomic ratio of unoxidized iron to unoxidized liquid zirconium plus uranium for the formation of a solid protective oxide below 2800 K is estimated for a temperature, T (in Kelvin), as follows:(unoxidized iron)/(unoxidized zirconium + turanium) = (1/28){5.7/exp[-(147 061 + 12.08T log(T) - 61.03T - 0.000555T 2 /1.986T)]} 1/2 .As long as this limit is not exceeded, either zirconium or uranium metal oxidation rates and heating describe the corium oxidation rate. If this limit is exceeded, diffusion of steam to the corium surface will limit the oxidation rate, and linear time-dependent growth of a nonprotective, mostly FeO, layer will occur below the protective (Zr,U) O 2 scale. When this happens, the oxidation should be at the constant rate given by the thickness of the protective layer. Heat generation should be similar to that of iron oxidation

Corium Oxidation at Temperatures Above 2000 K

Energy Technology Data Exchange (ETDEWEB)

Hagrman, Donald Lee; Rempe, Joy Lynn

2001-02-01

A mechanistic model, based on a quasi-equilibrium analysis of oxidation reactions, is proposed for predicting high-temperature corium oxidation. The analysis suggests that oxide forming on the surface of corium containing uranium, zirconium, and iron is similar to the oxides formed on zirconium and uranium as long as there is a small percentage of unoxidized zirconium or uranium in the metallic phase. This is because of the higher affinity of zirconium and uranium for oxygen. Hence, oxidation rates and heat production rates are similar to (U,Zr) compounds until nearly all the uranium and zirconium in the corium oxidizes. Oxidation rates after this point are predicted to be similar to those implied by the oxide thickness present when the forming oxide ceases to be protective, and heat generation rates should be similar to those implied by iron oxidation, i.e., ~4% of the zirconium oxidation heating rate. The maximum atomic ratio of unoxidized iron to unoxidized liquid zirconium plus uranium for the formation of a solid protective oxide below 2800 K is estimated for a temperature, T (in Kelvin), as follows: (unoxidized iron)/(unoxidized zirconium + turanium) = (1/28){5.7/exp[-(147 061 + 12.08T log(T) - 61.03T - 0.000555T2/1.986T)]}1/2. As long as this limit is not exceeded, either zirconium or uranium metal oxidation rates and heating describe the corium oxidation rate. If this limit is exceeded, diffusion of steam to the corium surface will limit the oxidation rate, and linear time-dependent growth of a nonprotective, mostly FeO, layer will occur below the protective (Zr,U) O2 scale. When this happens, the oxidation should be at the constant rate given by the thickness of the protective layer. Heat generation should be similar to that of iron oxidation.

Fatigue-induced dislocation structure of titanium alloy VT5-1ct at temperatures of 293-11 K

Energy Technology Data Exchange (ETDEWEB)

Grinberg, N.M. (Inst. for Low Temperature Physics and Engineering, Ukrainian Academy of Sciences, Kharkov (Ukraine)); Aleksenko, E.N. (Inst. for Low Temperature Physics and Engineering, Ukrainian Academy of Sciences, Kharkov (Ukraine)); Moskalenko, V.A. (Inst. for Low Temperature Physics and Engineering, Ukrainian Academy of Sciences, Kharkov (Ukraine)); Smirnov, A.R.N. (Inst. for Low Temperature Physics and Engineering, Ukrainian Academy of Sciences, Kharkov (Ukraine)); Yakovenko, L.F. (Inst. for Low Temperature Physics and Engineering, Ukrainian Academy of Sciences, Kharkov (Ukraine)); Mozhaev, A.V. (Inst. for Low Temperature Physics and Engineering, Ukrainian Academy of Sciences, Kharkov (Ukraine)); Arinushkin, I.A. (Inst. for Low Temperature Physics and Engineering, Ukrainian Academy of Sciences, Kharkov (Ukraine))

1993-07-05

The dislocation structure formed during the final stage of fatigue at high- and low-amplitude stresses at T=293 K in air and T=293, 93 and 11 K in high vacuum is studied on the Ti alloy VT5-1ct which has been prepared by two processing methods. The [sigma]-N curves are plotted for corresponding experimental conditions. It is shown that slip alone is responsible for the plastic deformation. The characteristic features of the dislocation structure formed are reported. The morphology of the a phase does not influence the character of the dislocation structure. At lower temperatures, the substructure remains practically unaltered, although the likelihood of uniformly distributed dislocations is lower. The lifetime is essentially dependent on the environment, temperature and the alloy microstructure, the latter being especially important at low temperatures in the high-amplitude region. (orig.)

Isothermal martensite formation at sub-zero temperatures

DEFF Research Database (Denmark)

Stojko, Allan; Hansen, Mikkel Fougt; Slycke, Jan

2010-01-01

austenitized and quenched in oil and thereafter investigated with vibrating sample agnetometry, which allows a quantitative assessment of the fraction of retained austenite as a function of the subzero temperature and time. Isothermal martensite formation was observed on interrupting the continuous cooling (5...... with a continuation of the martensitic transformation. On prolonged isothermal holding a volume reduction was observed for AISI 52100, but not for AISI 1070. A mechanism is proposed that explains the occurrence of isothermal martensite formation....

Beyond Zero Based Budgeting.

Science.gov (United States)

Ogden, Daniel M., Jr.

1978-01-01

Suggests that the most practical budgeting system for most managers is a formalized combination of incremental and zero-based analysis because little can be learned about most programs from an annual zero-based budget. (Author/IRT)

Zero modes and entanglement entropy

Energy Technology Data Exchange (ETDEWEB)

Yazdi, Yasaman K. [Perimeter Institute for Theoretical Physics,31 Caroline St. N., Waterloo, ON, N2L 2Y5 (Canada); Department of Physics and Astronomy, University of Waterloo,200 University Avenue West, Waterloo, ON, N2L 3G1 (Canada)

2017-04-26

Ultraviolet divergences are widely discussed in studies of entanglement entropy. Also present, but much less understood, are infrared divergences due to zero modes in the field theory. In this note, we discuss the importance of carefully handling zero modes in entanglement entropy. We give an explicit example for a chain of harmonic oscillators in 1D, where a mass regulator is necessary to avoid an infrared divergence due to a zero mode. We also comment on a surprising contribution of the zero mode to the UV-scaling of the entanglement entropy.

Exceptional curves on smooth rational surfaces with -K not nef and of self-intersection zero

International Nuclear Information System (INIS)

Lahyane, Mustapha

2001-08-01

We prove that a smooth rational surface X defined over the field of complex numbers having an anti-canonical divisor not nef and of self-intersection zero has a finite number of (-1)-curves. A (-1)-curve is a smooth rational curve of self-interaction -1. By giving an example, we also show that X may have no (-2)-curves, a (-2)-curve is a smooth rational curve of self-intersection -2. (author)

NRC Microwave Refractive Index Gas Thermometry Implementation Between 24.5 K and 84 K

Science.gov (United States)

Rourke, P. M. C.

2017-07-01

The implementation of microwave refractive index gas thermometry at the National Research Council between 24.5 K and 84 K is reported. A new gas-handling system for accurate control and measurement of experimental gas pressure has been constructed, and primary thermometry measurements have been taken using a quasi-spherical copper resonator and helium gas at temperatures corresponding to three defining fixed points of the International Temperature Scale of 1990 (ITS-90). These measurements indicate differences between the thermodynamic temperature T and ITS-90 temperature T_{90} of ( T - T_{90} ) = -0.60 ± 0.56 mK at T_{90} = 24.5561 K, ( T - T_{90} ) = -2.0 ± 1.3 mK at T_{90} = 54.3584 K, and ( T - T_{90} ) = -4.0 ± 2.9 mK at T_{90} = 83.8058 K. The present results at T_{90} = 24.5561 K and T_{90} = 83.8058 K agree with previously reported measurements from other primary thermometry techniques of acoustic gas thermometry and dielectric constant gas thermometry, and the result at T_{90} = 54.3584 K provides new information in a temperature region where there is a gap in other recent data sets.

Temperature Measurements Using Type K Thermocouples and the Fluke Helios Plus 2287A Datalogger

DEFF Research Database (Denmark)

Artmann, Nikolai; Vonbank, R.; Jensen, Rasmus Lund

the circuit creates a circuit in which the two legs generate different voltages, leaving a small difference in voltage available for measurement (Figure 1). That difference increases with temperature, and can typically be between one and seventy micro-volts per Kelvin (μV/K) for the modern range of available...

Zero-gravity movement studies

Science.gov (United States)

Badler, N. I.; Fishwick, P.; Taft, N.; Agrawala, M.

1985-01-01

The use of computer graphics to simulate the movement of articulated animals and mechanisms has a number of uses ranging over many fields. Human motion simulation systems can be useful in education, medicine, anatomy, physiology, and dance. In biomechanics, computer displays help to understand and analyze performance. Simulations can be used to help understand the effect of external or internal forces. Similarly, zero-gravity simulation systems should provide a means of designing and exploring the capabilities of hypothetical zero-gravity situations before actually carrying out such actions. The advantage of using a simulation of the motion is that one can experiment with variations of a maneuver before attempting to teach it to an individual. The zero-gravity motion simulation problem can be divided into two broad areas: human movement and behavior in zero-gravity, and simulation of articulated mechanisms.

Supersymmetry at finite temperature

International Nuclear Information System (INIS)

Clark, T.E.; Love, S.T.

1983-01-01

Finite-temperature supersymmetry (SUSY) is characterized by unbroken Ward identities for SUSY variations of ensemble averages of Klein-operator inserted imaginary time-ordered products of fields. Path-integral representations of these products are defined and the Feynman rules in superspace are given. The finite-temperature no-renormalization theorem is derived. Spontaneously broken SUSY at zero temperature is shown not to be restored at high temperature. (orig.)

Temperature and voltage dependence of barrier height and ideality factor in Au/0.07 graphene-doped PVA/n-Si structures

Science.gov (United States)

Altındal Yerişkin, S.; Balbaşı, M.; Demirezen, S.

2017-04-01

In this study, Au/0.07 graphene-doped PVA/n-Si structures were fabricated and current conduction mechanism in these structures were investigated in the temperature range of 80-380 K through forward bias current-voltage ( I- V) measurements. Main electrical parameters were extracted from I-V data. Zero-bias barrier height (\\overline{Φ}_{B0}) and ideality factor (n) were found strong functions of temperature and their values ranged from 0.234 eV and 4.98 (at 80 K) to 0.882 eV and 1.15 (at 380 K), respectively. Φ ap versus q/2k T plot was drawn to obtain an evidence of a Gaussian distribution of the barrier heights (BHs) and it revealed two distinct linear regions with different slopes and intercepts. The mean values of BH ( Φ Bo) and zero-bias standard deviation (σ s ) were obtained from the intercept and slope of the linear regions of this plot as 1.30 eV and 0.16 V for the first region (280-380 K) and 0.74 eV and 0.085 V for the second region (80-240 K), respectively. Thus, the values of \\overline{Φ}_{B0} and effective Richardson constant ( A*) were also found from the intercept and slope of the modified Richardson plot [ln( I s /T 2) - q 2 σ o 2 /2k 2 T 2 vs q/ kT] as 1.31 eV and 130 A/cm2 K2 for the first region and 0.76 eV and 922 A/cm2 K2 for the second region, respectively. The value of A* for the first region was very close to the theoretical value for n-Si (112 A/cm2 K2). The energy density distribution profile of surface states (Nss) was also extracted from the forward bias I-V data by taking into account voltage dependent effective BH (Φe) and n.

NASA Net Zero Energy Buildings Roadmap

Energy Technology Data Exchange (ETDEWEB)

Pless, S.; Scheib, J.; Torcellini, P.; Hendron, B.; Slovensky, M.

2014-10-01

In preparation for the time-phased net zero energy requirement for new federal buildings starting in 2020, set forth in Executive Order 13514, NASA requested that the National Renewable Energy Laboratory (NREL) to develop a roadmap for NASA's compliance. NASA detailed a Statement of Work that requested information on strategic, organizational, and tactical aspects of net zero energy buildings. In response, this document presents a high-level approach to net zero energy planning, design, construction, and operations, based on NREL's first-hand experience procuring net zero energy construction, and based on NREL and other industry research on net zero energy feasibility. The strategic approach to net zero energy starts with an interpretation of the executive order language relating to net zero energy. Specifically, this roadmap defines a net zero energy acquisition process as one that sets an aggressive energy use intensity goal for the building in project planning, meets the reduced demand goal through energy efficiency strategies and technologies, then adds renewable energy in a prioritized manner, using building-associated, emission- free sources first, to offset the annual energy use required at the building; the net zero energy process extends through the life of the building, requiring a balance of energy use and production in each calendar year.

Getting to Net Zero

Energy Technology Data Exchange (ETDEWEB)

2016-09-01

The technology necessary to build net zero energy buildings (NZEBs) is ready and available today, however, building to net zero energy performance levels can be challenging. Energy efficiency measures, onsite energy generation resources, load matching and grid interaction, climatic factors, and local policies vary from location to location and require unique methods of constructing NZEBs. It is recommended that Components start looking into how to construct and operate NZEBs now as there is a learning curve to net zero construction and FY 2020 is just around the corner.

Home-made temperature monitoring system from four-channel K-type thermocouples via internet of thing technology platform

Science.gov (United States)

Detmod, Thitaporn; Özmen, Yiǧiter; Songkaitiwong, Kittiphot; Saenyot, Khanuengchat; Locharoenrat, Kitsakorn; Lekchaum, Sarai

2018-06-01

This paper is aimed to design and construct the home-made temperature monitoring system from four-channel K-type thermocouples in order to improve the temperature measurement based on standard evaluation measurements guidance. The temperature monitoring system was capable to record the temperature on SD card and to display the realtime temperature on Internet of Thing Technology platform. The temperature monitoring system was tested in terms of the temperature measurement accuracy and delay response time. It was found that a standard deviation was acceptable as compared to the Instrument Society of America. The response time of the microcontroller to SD card was 2 sec faster than that of the microcontroller to Thingspeak.