NASA Astrophysics Data System (ADS)
Zhu, Zun-Lue; Fu, Hong-Zhi; Sun, Jin-Feng; Liu, Yu-Fang; Shi, De-Heng; Xu, Guo-Liang
2009-08-01
The first-principles plane-wave pseudopotential method using the generalized gradient approximation within the framework of density functional theory is applied to anaylse the equilibrium lattice parameters, six independent elastic constants, bulk moduli, thermal expansions and heat capacities of MoSi2. The quasi-harmonic Debye model, using a set of total energy versus cell volume obtained with the plane-wave pseudopotential method, is applied to the study of the elastic properties, thermodynamic properties and vibrational effects. The calculated zero pressure elastic constants are in overall good agreement with the experimental data. The calculated heat capacities and the thermal expansions agree well with the observed values under ambient conditions and those calculated by others. The results show that the temperature has hardly any effect under high pressure.
Optical, elastic and thermal properties of ZB-AlN semiconductor from first-principle calculations
NASA Astrophysics Data System (ADS)
Kumar, V.; Singh, Bhanu P.; Chandra, Satish
2017-04-01
The optical, elastic and thermal properties of zincblende aluminium nitride have been studied. The refractive index, absorption coefficient, reflectivity, dielectric constant, extinction coefficient, and energy-loss spectrum have been calculated using the pseudo-potential method under density functional theory at different pressures. The heat capacity, Debye temperature and phonon frequencies have been calculated using CASTEP code at 0 GPa. The elastic stiffness constants, bulk modulus, Young's modulus, shear modulus and pressure derivatives of elastic constants have also been calculated. The calculated results are compared with the available experimental and theoretical data. Reasonably good agreement has been found between them.
Optical, elastic and thermal properties of ZB-AlN semiconductor from first-principle calculations
NASA Astrophysics Data System (ADS)
Kumar, V.; Singh, Bhanu P.; Chandra, Satish
2016-12-01
The optical, elastic and thermal properties of zincblende aluminium nitride have been studied. The refractive index, absorption coefficient, reflectivity, dielectric constant, extinction coefficient, and energy-loss spectrum have been calculated using the pseudo-potential method under density functional theory at different pressures. The heat capacity, Debye temperature and phonon frequencies have been calculated using CASTEP code at 0 GPa. The elastic stiffness constants, bulk modulus, Young's modulus, shear modulus and pressure derivatives of elastic constants have also been calculated. The calculated results are compared with the available experimental and theoretical data. Reasonably good agreement has been found between them.
Calculated transport properties of CdO: thermal conductivity and thermoelectric power factor
Lindsay, Lucas R.; Parker, David S.
2015-10-01
We present first principles calculations of the thermal and electronic transport properties of the oxide semiconductor CdO. In particular, we find from theory that the accepted thermal conductivity κ value of 0.7 Wm-1K-1 is approximately one order of magnitude too small; our calculations of κ of CdO are in good agreement with recent measurements. We also find that alloying of MgO with CdO is an effective means to reduce the lattice contribution to κ, despite MgO having a much larger thermal conductivity. We further consider the electronic structure of CdO in relation to thermoelectric performance, finding that large thermoelectric powermore » factors may occur if the material can be heavily doped p-type. This work develops insight into the nature of thermal and electronic transport in an important oxide semiconductor.« less
Calculated transport properties of CdO: thermal conductivity and thermoelectric power factor
Lindsay, Lucas R.; Parker, David S.
2015-10-01
We present first principles calculations of the thermal and electronic transport properties of the oxide semiconductor CdO. In particular, we find from theory that the accepted thermal conductivity κ value of 0.7 Wm^{-1}K^{-1} is approximately one order of magnitude too small; our calculations of κ of CdO are in good agreement with recent measurements. We also find that alloying of MgO with CdO is an effective means to reduce the lattice contribution to κ, despite MgO having a much larger thermal conductivity. We further consider the electronic structure of CdO in relation to thermoelectric performance, finding that large thermoelectric power factors may occur if the material can be heavily doped p-type. This work develops insight into the nature of thermal and electronic transport in an important oxide semiconductor.
NASA Astrophysics Data System (ADS)
Bock, Steffen; Bich, Eckard; Vogel, Eckhard; Dickinson, Alan S.; Vesovic, Velisa
2004-05-01
The transport properties of pure carbon dioxide have been calculated from the intermolecular potential using the classical trajectory method. Results are reported in the dilute-gas limit for thermal conductivity and thermomagnetic coefficients for temperatures ranging from 200 K to 1000 K. Three recent carbon dioxide potential energy hypersurfaces have been investigated. Since thermal conductivity is influenced by vibrational degrees of freedom, not included in the rigid-rotor classical trajectory calculation, a correction for vibration has also been employed. The calculations indicate that the second-order thermal conductivity corrections due to the angular momentum polarization (<2%) and velocity polarization (<1%) are both small. Thermal conductivity values calculated using the potential energy hypersurface by Bukowski et al. (1999) are in good agreement with the available experimental data. They underestimate the best experimental data at room temperature by 1% and in the range up to 470 K by 1%-3%, depending on the data source. Outside this range the calculated values, we believe, may be more reliable than the currently available experimental data. Our results are consistent with measurements of the thermomagnetic effect at 300 K only when the vibrational degrees of freedom are considered fully. This excellent agreement for these properties indicates that particularly the potential surface of Bukowski et al. provides a realistic description of the anisotropy of the surface.
Elastic and Thermal Properties of Silicon Compounds from First-Principles Calculations
NASA Astrophysics Data System (ADS)
Hou, Haijun; Zhu, H. J.; Cheng, W. H.; Xie, L. H.
2016-07-01
The structural and elastic properties of V-Si (V3Si, VSi2, V5Si3, and V6Si5) compounds are studied by using first-principles method. The calculated equilibrium lattice parameters and formation enthalpy are in good agreement with the available experimental data and other theoretical results. The calculated results indicate that the V-Si compounds are mechanically stable. Elastic properties including bulk modulus, shear modulus, Young's modulus, and Poisson's ratio are also obtained. The elastic anisotropies of V-Si compounds are investigated via the three-dimensional (3D) figures of directional dependences of reciprocals of Young's modulus. Finally, based on the quasi-harmonic Debye model, the internal energy, Helmholtz free energy, entropy, heat capacity, thermal expansion coefficient, Grüneisen parameter, and Debye temperature of V-Si compounds have been calculated.
Lattice EFT calculation of thermal properties of low-density neutron matter
NASA Astrophysics Data System (ADS)
Abe, T.; Seki, R.
2011-09-01
Thermal properties of low-density neutron matter are investigated by lattice calculation with nuclear effective field theory without pions up to the next-to-leading order. The 1S0 pairing gap is extracted near zero temperature at low densities. We find that the pairing gap is smaller than the BCS approximation with the conventional NN potentials, but not as small as those by various many-body calculations beyond BCS approximation. Our result is consistent with the recent Green's Function Monte Carlo calculation within the statistical errors. The critical temperature of the normal-to-superfluid phase transition and the pairing temperature scale are also extracted at low densities, and the phase diagram is given. We find that the physics of low-density neutron matter is clearly identified as being BCS-BEC crossover.
NASA Astrophysics Data System (ADS)
Vila, F. D.; Rehr, J. J.
Effects of thermal vibrations are essential to obtain a more complete understanding of the properties of complex materials. For example, they are important in the analysis and simulation of x-ray absorption spectra (XAS). In previous work we introduced an ab initio approach for a variety of vibrational effects, such as crystallographic and XAS Debye-Waller factors, Debye and Einstein temperatures, and thermal expansion coefficients. This approach uses theoretical dynamical matrices from which the locally-projected vibrational densities of states are obtained using a Lanczos recursion algorithm. In this talk I present recent improvements to our implementation, which permit simulations of more complex materials with up to two orders of magnitude larger simulation cells. The method takes advantage of parallelization in calculations of the dynamical matrix with VASP. To illustrate these capabilities we discuss two problems of considerable interest: negative thermal expansion in ZrW2O8; and local inhomogeneities in the elastic properties of supported metal nanoparticles. Both cases highlight the importance of a local treatment of vibrational properties. Supported by DOE Grant DE-FG02-03ER15476, with computer support from DOE-NERSC.
NASA Technical Reports Server (NTRS)
Cleghorn, T. F.
1994-01-01
MIPROPS is a set of programs which gives the thermophysical and transport properties of selected fluids. Although these programs are written in FORTRAN 77 for implementation on microcomputers, they are direct translations of interactive FORTRAN IV programs which were originally developed for large mainframes. MIPROPS calculates the properties of fluids in both the liquid and vapor states over a wide range of temperatures and pressures. The fluids included are: helium, parahydrogen, nitrogen, oxygen, argon, nitrogen trifluoride, methane, ethylene, ethane, propane, and iso- and normal butane. All of the programs except for the helium program utilize the same mathematical model of the equation of state. A separate program was necessary for helium, as the model for the helium thermodynamic surface is of a different form. The input variables are any two of pressure, density, or temperature for the single phase regions, and either pressure or temperature for the saturated liquid or vapor states. The output is pressure, density, temperature, internal energy, enthalpy, entropy, specific heat capacities, and speed of sound. In addition, viscosity, thermal conductivity, and dielectric constants are calculated for most of the fluids. The user can select either a single point or a table of output values for a specified temperature range, and can display the data either in engineering or metric units. This machine independent FORTRAN 77 program was implemented on an IBM PC XT with an MS-DOS 3.21 operating system. It has a memory requirement of approximately 100K. The program was developed in 1986.
NASA Astrophysics Data System (ADS)
Mebrouki, M.; Ouahrani, T.; Çiftci, Y. Öztekin
2016-07-01
Using a toolkit of theoretical techniques comprising ab initio density functional theory calculations and quasiharmonic approximation, we investigate temperature dependence of dynamical properties of BaVO_3 perovskite. This interest is triggered by the fact that, recently, it was possible to synthesize a BaVO_3 perovskite, in a cubic phase, at high pressure and temperature. First-principle calculations are achieved thanks to recent development in numerical facilities, especially phonon dispersion curves which are then fully obtained. Elastic constants of the compound are dependent on temperature due to the inevitable anharmonic effects in solids. We show that at low temperature, the full account of the thermal effects incorporating the phonon densities and Sommerfeld model is more appropriate to calculate the thermal properties of a metal.
Calculated elastic and thermal properties of MGO at high pressures and temperatures
NASA Astrophysics Data System (ADS)
Isaak, Donald G.; Cohen, Ronald E.; Mehl, Michael J.
1990-05-01
Using the potential-induced breathing model, we calculate the pressure and temperature dependence of the thermoelastic properties of MgO. These calculations represent the first attempt to obtain a consistent set of thermodynamic elastic moduli for an oxide from an ab initio model over a wide range of pressure and temperature. By assuming the quasi-harmonic approximation for the free energies, we find excellent agreement between the temperature dependence of calculated elastic moduli and those obtained from experiments. Comparison of the calculated athermal and isothermal elastic moduli shows approximations using athermal values to be unreliable at high temperature. The elastic moduli for MgO are presented for pressures and temperatures appropriate for the lower mantle, a regime in which elastic moduli cannot be obtained by direct measurement.
Tight binding calculations of vibrational and thermal properties of amorphous silicon
NASA Astrophysics Data System (ADS)
Mehl, Michael; Feldman, Joseph; Papaconstantopoulos, Dimitris; Bernstein, Noam
2006-03-01
By displacing atoms by different amounts and computing atomic forces within the NRL tight binding method we obtain all second order (harmonic) and some third order (anharmonic) coupling constants of a 1000 atom TB-relaxed Wooten CRN model of amorphous silicon. The harmonic force constant results allow us to study various properties including vibrational density of states, dynamic structure factors, specific heat and thermal conductivity within Kubo theory. We shall present results of these applications and compare to experiment and previous work based on the Stillinger Weber potential.
NASA Astrophysics Data System (ADS)
Tsuchiya, Yooko; Yoshii, Noriyuki; Iwatsubo, Tetsushiro
2004-08-01
Since heat storage technology contributes greatly to the effective use of energy, we are attempting to develop latent heat storage materials. If computer simulations enable the estimation of material properties prior to experiments, they will provide us with very effective tools for the development of new materials. We use molecular dynamics calculations to predict the melting points and latent heats of fusion, which are crucial thermal properties for evaluating the suitability of heat-storage materials. As the object of calculation, poly(vinyl alcohol) (PVA) was chosen, because polymer materials are effective in that they can be made to cover all temperature ranges by changing the molecular weight. The melting points were determined from the volume change, and the latent heats of fusion were determined from the internal energy. As for these calculations, it was ascertained that these thermal properties were suitable values in comparison with the results of actual calorimetry. From the comparative calculation of the polymer consistent force field (PCFF) and optimized potentials for liquid simulations (OPLS) force field, it was shown that the intermolecular potential could be simplified. Moreover, the stability of the structural isomer of PVA and the state of the hydrogen bond were evaluated, because a strong intermolecular bond leads to structural stability and a high melting temperature.
NASA Astrophysics Data System (ADS)
Kurban, Mustafa; Erkoç, Şakir
2017-04-01
Surface and core formation, thermal and electronic properties of ternary cubic CdZnTe clusters are investigated by using classical molecular dynamics (MD) simulations and density functional theory (DFT) calculations. In this work, MD simulations of the CdZnTe clusters are performed by means of LAMMPS by using bond order potential (BOP). MD simulations are carried out at different temperatures to study the segregation phenomena of Cd, Zn and Te atoms, and deviation of clusters and heat capacity. After that, using optimized geometries obtained, excess charge on atoms, dipole moments, highest occupied molecular orbitals, lowest unoccupied molecular orbitals, HOMO-LUMO gaps (Eg) , total energies, spin density and the density of states (DOS) have been calculated with DFT. Simulation results such as heat capacity and segregation formation are compared with experimental bulk and theoretical results.
First-principle calculation on mechanical and thermal properties of B2-NiSc with point defects
NASA Astrophysics Data System (ADS)
Yuan, Zhipeng; Cui, Hongbao; Guo, Xuefeng
2017-01-01
Using the first-principles plane-wave pseudo-potential method based on density functional theory, the effect of vacancy and anti-position defect on the mechanical and thermal properties of B2-NiSc intermetallics were discussed in detail. Several parameters, such as the shear modulus, bulk modulus, modulus of elasticity, C 11–C 11, the Debye temperature and Poisson's ratio, have been calculated to evaluate the effect of vacancy and anti-position defect on the hardness, ductility and thermal properties of B2-NiSc intermetallics. The results show that VNi, ScNi, VSc and NiSc the four point defects all make the crystal hardness decrease and improve plasticity of B2-NiSc intermetallics. The entropy, enthalpy and free energy of VNi, ScNi, VSc and NiSc are monotonously changed as temperature changes. From the perspective of free energy, NiSc is the most stable, while ScNi is the most unstable. Debye temperature of NiSc intermetallics with four different point defects shows VNi, ScNi, VSc and NiSc the four point defects all reduce the stability of B2-NiSc intermetallics. Project supported by the National Natural Science Foundation of China (Nos. 51301063, 51571086) and the Talent Introduction Foundation of Henan Polytechnic University (No. Y-2009).
PHYSICOCHEMICAL PROPERTY CALCULATIONS
Computer models have been developed to estimate a wide range of physical-chemical properties from molecular structure. The SPARC modeling system approaches calculations as site specific reactions (pKa, hydrolysis, hydration) and `whole molecule' properties (vapor pressure, boilin...
Abe, T.; Seki, R.
2009-05-15
Thermal properties of low-density neutron matter are investigated by determinantal quantum Monte Carlo lattice calculations on 3+1 dimensional cubic lattices. Nuclear effective field theory (EFT) is applied using the pionless single- and two-parameter neutron-neutron interactions, determined from the {sup 1}S{sub 0} scattering length and effective range. The determination of the interactions and the calculations of neutron matter are carried out consistently by applying EFT power counting rules. The thermodynamic limit is taken by the method of finite-size scaling, and the continuum limit is examined in the vanishing lattice filling limit. The {sup 1}S{sub 0} pairing gap at T{approx_equal}0 is computed directly from the off-diagonal long-range order of the spin pair-pair correlation function and is found to be approximately 30% smaller than BCS calculations with the conventional nucleon-nucleon potentials. The critical temperature T{sub c} of the normal-to-superfluid phase transition and the pairing temperature scale T* are determined, and the temperature-density phase diagram is constructed. The physics of low-density neutron matter is clearly identified as being a BCS-Bose-Einstein condensation crossover.
NASA Technical Reports Server (NTRS)
Wanser, K. H.
1981-01-01
Silicon has interesting harmonic and anharmonic properties such as the low lying transverse acoustic modes at the X and L points of the Brillouin zone, negative Gruneisen parameters, negative thermal expansion and anomalous acoustic attenuation. In an attempt to understand these properties, a lattice dynamical model employing long range, nonlocal, dipole-dipole interactions was developed. Analytic expression for the Gruneisen parameters of several modes are presented. These expressions explain how the negative Gruneisen parameters arise. This model is applied to the calculation of the thermal expansion of silicon from 5K to 1700K. The thermoelastic contribution to the acoustic attenuation of silicon is computed from 1 to 300 K. Strong attenuation anomalies associated with negative thermal expansion are found in the vicinity of 17K and 125K.
NASA Astrophysics Data System (ADS)
Boumaza, A.; Ghemid, S.; Chouahda, Z.; Meradji, H.; El Haj Hassan, F.
2012-09-01
The structural, electronic, elastic, thermal and thermodynamic properties of Zn1-xBexTe semiconductor alloys have been investigated using the full-potential linearized augmented plane wave method within density functional theory. We use both the Wu-Cohen and the Engel-Vosko generalized gradient approximations of the exchange-correlation energy that are based on the optimization of the total energy and the corresponding potential, respectively. The ground state properties such as lattice constants, bulk modulus and elastic constants are in good agreement with numerous experimental and theoretical data. The calculated band structures show that the band gap undergoes a direct to indirect transition at a given concentration. A regular-solution model is used to investigate the thermodynamic stability of the alloy that mainly indicates a phase miscibility gap. In addition, the quasi-harmonic Debye model is applied to determine the thermal properties of the alloy.
NASA Astrophysics Data System (ADS)
Ben hassen, C.; Boujelbene, M.; Bahri, M.; Zouari, N.; Mhiri, T.
2014-09-01
The present paper undertakes the study of a new hybrid compound [2-CH3C6H4NH3]2SeO4 characterized by the X-ray diffraction, IR, DFT calculation, TG-DTA, DSC and electrical conductivity. This new organic-inorganic hybrid compound crystallizes in the monoclinic system with P21/c space group and the following parameters a = 14.821 (5) Å; b = 16.245 (5) Å; c = 6.713 (5) Å; ß = 102.844 (5)°, Z = 4 and V = 1575.8 (14) Å3. The atomic arrangement can be described as isolated tetrahedral SeO42- connected with the organic groups by means of Nsbnd H⋯O hydrogen bonds to form infinite sinusoidal chains in the c-direction. BHHLYP/6-311g** method was used to determine the harmonic frequencies for two optimized cluster structures. The calculated modes were animated using the Molden graphical package to give tentative assignments of the observed IR spectra. Thermal analysis of the title compound does not indicate the occurrence of a phase transition in the temperature range of 300-650 K. Dielectric study of this compound has been measured, in order to determine the conductivity. The conductivity relaxation parameters associated with some H+ conduction have been determined from an analysis of the M″/M″max spectrum measured in a wide temperature range.
NASA Astrophysics Data System (ADS)
Łuszczak, Katarzyna; Persano, Cristina; Braun, Jean; Stuart, Finlay
2016-04-01
Low temperature thermochronometers are mainly used to decipher crustal denudation histories. However, these methods provide cooling paths that can be confidently translated into denudation rates only if the geothermal gradient at the time of cooling is known. As past geothermal gradients cannot be directly measured, they can be sometimes estimated from the thermochronometric data, when borehole data or vertical profiles are available. In all the other cases, our knowledge of the spatial and temporal variation of the geothermal gradient is limited. It is common practice in many thermochronometric studies to calculate the amounts and rates of denudation through time assuming a constant, average present-day value for the geothermal gradient. In this study, using 1D and 3D (Pecube) models, we have investigated the impact of crustal heat production and thermal conductivity (κ) on the estimated values of denudation, taking central west Britain as our case study. In this region, the apatite fission track (AFT) ages describe a characteristic U-shape pattern with early Cenozoic ages in the English Lake District and older, up to 200 Ma ages northwards in S Scotland, and southwards in N Wales. This pattern, which could be referred to a difficult to justify localized, differential denudation, can actually be best explained as an effect of the spatially variable heat production. The insulating effect of low thermal conductivity Upper Mesozoic sedimentary rocks, composed largely by chalk, increases the palaeogeothermal gradient and reduces the amounts of denudation, especially in the Lake District, where a heat productive granite batholith increases the local heat flow. The observed AFT age pattern may be, therefore, explained without any significant variation of early Cenozoic denudation across central west Britain. If the thermal proprieties of the crust are not taken into account, denudation in the Lake District will be overestimated by a factor of 1.5-2.0 and the mechanisms
NASA Astrophysics Data System (ADS)
Habershon, Scott
2013-09-01
We introduce a new approach for calculating quantum time-correlation functions and time-dependent expectation values in many-body thermal systems; both electronically adiabatic and non-adiabatic cases can be treated. Our approach uses a path integral simulation to sample an initial thermal density matrix; subsequent evolution of this density matrix is equivalent to solution of the time-dependent Schrödinger equation, which we perform using a linear expansion of Gaussian wavepacket basis functions which evolve according to simple classical-like trajectories. Overall, this methodology represents a formally exact approach for calculating time-dependent quantum properties; by introducing approximations into both the imaginary-time and real-time propagations, this approach can be adapted for complex many-particle systems interacting through arbitrary potentials. We demonstrate this method for the spin Boson model, where we find good agreement with numerically exact calculations. We also discuss future directions of improvement for our approach with a view to improving accuracy and efficiency.
Thermal radiative properties: Coatings.
NASA Technical Reports Server (NTRS)
Touloukian, Y. S.; Dewitt, D. P.; Hernicz, R. S.
1972-01-01
This volume consists, for the most part, of a presentation of numerical data compiled over the years in a most comprehensive manner on coatings for all applications, in particular, thermal control. After a moderately detailed discussion of the theoretical nature of the thermal radiative properties of coatings, together with an overview of predictive procedures and recognized experimental techniques, extensive numerical data on the thermal radiative properties of pigmented, contact, and conversion coatings are presented. These data cover metallic and nonmetallic pigmented coatings, enamels, metallic and nonmetallic contact coatings, antireflection coatings, resin coatings, metallic black coatings, and anodized and oxidized conversion coatings.
Thermal Properties Measurement Report
Carmack, Jon; Braase, Lori; Papesch, Cynthia; Hurley, David; Tonks, Michael; Zhang, Yongfeng; Gofryk, Krzysztof; Harp, Jason; Fielding, Randy; Knight, Collin; Meyer, Mitch
2015-08-01
The Thermal Properties Measurement Report summarizes the research, development, installation, and initial use of significant experimental thermal property characterization capabilities at the INL in FY 2015. These new capabilities were used to characterize a U_{3}Si_{2} (candidate Accident Tolerant) fuel sample fabricated at the INL. The ability to perform measurements at various length scales is important and provides additional data that is not currently in the literature. However, the real value of the data will be in accomplishing a phenomenological understanding of the thermal conductivity in fuels and the ties to predictive modeling. Thus, the MARMOT advanced modeling and simulation capability was utilized to illustrate how the microstructural data can be modeled and compared with bulk characterization data. A scientific method was established for thermal property measurement capability on irradiated nuclear fuel samples, which will be installed in the Irradiated Material Characterization Laboratory (IMCL).
NASA Astrophysics Data System (ADS)
Guezlane, M.; Baaziz, H.; El Haj Hassan, F.; Charifi, Z.; Djaballah, Y.
2016-09-01
Density functional theory (DFT) based on the full-potential linearized augmented plane wave (FP-LAPW) method is used to investigate the structural, electronic, magnetic and thermal properties of Co2CrxFe1-xX (X=Al, Si) full Heusler alloys, with L21 structure. The structural properties and spin magnetic moments are investigated by the generalized gradient approximations (GGA) minimizing the total energy. For band structure calculations, GGA, the Engel-Vosko generalized gradient approximation (EVGGA) and modified Becke-Johnson (mBJ) schemes are used. Results of density of states (DOS) and band structures show that these alloys are half-metallic ferromagnets (HMFS). A regular-solution model has been used to investigate the thermodynamic stability of the compounds Co2CrxFe1-xX that indicates a phase miscibility gap. The thermal effects using the quasi-harmonic Debye model are investigated within the lattice vibrations. The temperature and pressure effects on the heat capacities, Debye temperatures and entropy are determined from the non-equilibrium Gibbs functions.
Thermal properties of nanofluids.
Philip, John; Shima, P D
2012-11-15
Colloidal suspensions of fine nanomaterials in the size range of 1-100 nm in carrier fluids are known as nanofluids. For the last one decade, nanofluids have been a topic of intense research due to their enhanced thermal properties and possible heat transfer applications. Miniaturization and increased operating speeds of gadgets warranted the need for new and innovative cooling concepts for better performance. The low thermal conductivity of conventional heat transfer fluid has been a serious impediment for improving the performance and compactness of engineering equipments. Initial studies on thermal conductivity of suspensions with micrometer-sized particles encountered problems of rapid settling of particles, clogging of flow channels and increased pressure drop in the fluid. These problems are resolved by using dispersions of fine nanometer-sized particles. Despite numerous experimental and theoretical studies, it is still unclear whether the thermal conductivity enhancement in nanofluids is anomalous or within the predictions of effective medium theory. Further, many reports on thermal conductivity of nanofluids are conflicting due to the complex issues associated with the surface chemistry of nanofluids. This review provides an overview of recent advances in the field of nanofluids, especially the important material properties that affect the thermal properties of nanofluids and novel approaches to achieve extremely high thermal conductivities. The background information is also provided for beginners to better understand the subject.
LMR thermal hydraulics calculations in the US
Dunn, F.E.; Malloy, D.J.; Mohr, D.
1987-04-27
A wide range of thermal hydraulics computer codes have been developed by various organizations in the US. These codes cover an extensive range of purposes from within-assembly-wise pin temperature calculations to plant wide transient analysis. The codes are used for static analysis, for analysis of protected anticipated transients, and for analysis of a wide range of unprotected transients for the more recent inherently safe LMR designs. Some of these codes are plant-specific codes with properties of a specific plant built into them. Other codes are more general and can be applied to a number of plants or designs. These codes, and the purposes for which they have been used, are described.
NASA Astrophysics Data System (ADS)
Zhou, Bo; Su, Qing; He, De-Yan
2009-11-01
Using a first-principles approach based on density functional theory, this paper studies the electronic and dynamical properties of β-V2O5. A smaller band gap and much wider split-off bands have been observed in comparison with α-V2O5. The Raman- and infrared-active modes at the Γ point of the Brillouin zone are evaluated with LO/TO splitting, where the symbol denotes the longitudinal and transverse optical model. The nonresonant Raman spectrum of a β-V2O5 powder sample is also computed, providing benchmark theoretical results for the assignment of the experimental spectrum. The computed spectrum agrees with the available experimental data very well. This calculation helps to gain a better understanding of the transition from α- to β-V2O5.
NASA Technical Reports Server (NTRS)
Gupta, Roop N.; Yos, Jerrold M.; Thompson, Richard A.
1989-01-01
Reaction rate coefficients and thermodynamic and transport properties are provided for the 11-species air model which can be used for analyzing flows in chemical and thermal nonequilibrium. Such flows will likely occur around currently planned and future hypersonic vehicles. Guidelines for determining the state of the surrounding environment are provided. Approximate and more exact formulas are provided for computing the properties of partially ionized air mixtures in such environments.
NASA Technical Reports Server (NTRS)
Gupta, Roop N.; Yos, Jerrold M.; Thompson, Richard A.; Lee, Kam-Pui
1990-01-01
Reaction rate coefficients and thermodynamic and transport properties are reviewed and supplemented for the 11-species air model which can be used for analyzing flows in chemical and thermal nonequilibrium up to temperatures of 3000 K. Such flows will likely occur around currently planned and future hypersonic vehicles. Guidelines for determining the state of the surrounding environment are provided. Curve fits are given for the various species properties for their efficient computation in flowfield codes. Approximate and more exact formulas are provided for computing the properties of partially ionized air mixtures in a high energy environment. Limitations of the approximate mixing laws are discussed for a mixture of ionized species. An electron number-density correction for the transport properties of the charged species is obtained. This correction has been generally ignored in the literature.
1979-11-23
electrical energy. The theory involved in computing the thermal resistivity using the thermal needle method is presented in Appendix C. i The thermal...thermal needle , consist- ing of a stainless steel hypodermic tubing which contains iOR NATIONAL. ,NO. FN-TR-29 23 a heater element and a thermocouple...22 3.1 Thermal Needle ...................................... 22 3.2 Test Procedure ...................................... 23 3.3 Results
NASA Astrophysics Data System (ADS)
Dai, Xian-Qi; Zhao, Jian-Hua; Sun, Yong-Can; Wei, Shu-Yi; Wei, Guo-Hong
2010-09-01
The atomic and electronic structures of Tl and In on Si(111) surfaces are investigated using the first-principles total energy calculations. Total energy optimizations show that the energetically favored structure is 1/3 ML Tl adsorbed at the T4 sites on Si(111) surfaces. The adsorption energy difference of one Tl adatom between (√3 × √3) and (1 × 1) is less than that of each In adatom. The DOS indicates that Tl 6p and Si 3p electrons play a very important role in the formation of the surface states. It is concluded that the bonding of Tl adatoms on Si(111) surfaces is mainly polar covalent, which is weaker than that of In on Si(111). So Tl atom is more easy to be migrated than In atom in the same external electric field and the structures of Tl on Si(111) is prone to switch between (√3 × √3) and (1 × 1).
The calculation of thermophysical properties of nickel plasma
Apfelbaum, E. M.
2015-09-15
The thermophysical properties of Nickel plasma have been calculated for the temperatures 10–60 kK and densities less than 1 g/cm{sup 3}. These properties are the pressure, internal energy, heat capacity, and the electronic transport coefficients (electrical conductivity, thermal conductivity, and thermal power). The thermodynamic values have been calculated by means of the chemical model, which also allows one to obtain the ionic composition of considered plasma. The composition has been used to calculate the electronic transport coefficients within the relaxation time approximation. The results of the present investigation have been compared with the calculations of other researchers and available data of measurements.
Thermal Properties of oil sand
NASA Astrophysics Data System (ADS)
LEE, Y.; Lee, H.; Kwon, Y.; Kim, J.
2013-12-01
Thermal recovery methods such as Cyclic Steam Injection or Steam Assisted Gravity Drainage (SAGD) are the effective methods for producing heavy oil or bitumen. In any thermal recovery methods, thermal properties (e.g., thermal conductivity, thermal diffusivity, and volumetric heat capacity) are closely related to the formation and expansion of steam chamber within a reservoir, which is key factors to control efficiency of thermal recovery. However, thermal properties of heavy oil or bitumen have not been well-studied despite their importance in thermal recovery methods. We measured thermal conductivity, thermal diffusivity, and volumetric heat capacity of 43 oil sand samples from Athabasca, Canada, using a transient thermal property measurement instrument. Thermal conductivity of 43 oil sand samples varies from 0.74 W/mK to 1.57 W/mK with the mean thermal conductivity of 1.09 W/mK. The mean thermal diffusivity is 5.7×10-7 m2/s with the minimum value of 4.2×10-7 m2/s and the maximum value of 8.0×10-7 m2/s. Volumetric heat capacity varies from 1.5×106 J/m3K to 2.11×106 J/m3K with the mean volumetric heat capacity of 1.91×106 J/m3K. In addition, physical and chemical properties (e.g., bitumen content, electric resistivity, porosity, gamma ray and so on) of oil sand samples have been measured by geophysical logging and in the laboratory. We are now proceeding to investigate the relationship between thermal properties and physical/chemical properties of oil sand.
Lattice thermal conductivity of borophene from first principle calculation
Xiao, Huaping; Cao, Wei; Ouyang, Tao; Guo, Sumei; He, Chaoyu; Zhong, Jianxin
2017-01-01
The phonon transport property is a foundation of understanding a material and predicting the potential application in mirco/nano devices. In this paper, the thermal transport property of borophene is investigated by combining first-principle calculations and phonon Boltzmann transport equation. At room temperature, the lattice thermal conductivity of borophene is found to be about 14.34 W/mK (error is about 3%), which is much smaller than that of graphene (about 3500 W/mK). The contributions from different phonon modes are qualified, and some phonon modes with high frequency abnormally play critical role on the thermal transport of borophene. This is quite different from the traditional understanding that thermal transport is usually largely contributed by the low frequency acoustic phonon modes for most of suspended 2D materials. Detailed analysis further reveals that the scattering between the out-of-plane flexural acoustic mode (FA) and other modes likes FA + FA/TA/LA/OP ↔ TA/LA/OP is the predominant phonon process channel. Finally the vibrational characteristic of some typical phonon modes and mean free path distribution of different phonon modes are also presented in this work. Our results shed light on the fundamental phonon transport properties of borophene, and foreshow the potential application for thermal management community. PMID:28374853
NASA Astrophysics Data System (ADS)
Sun, Liang; Gao, Yimin; Yoshida, Katsumi; Yano, Toyohiko; Li, Yefei; Liu, Yangzhen
2017-01-01
Structural, electronic, elastic and thermal properties of Al4Si2C5 under constant pressure were investigated by using first-principles theory. The total volume of the cell decreased by almost 15.7% under 40 GPa which is smaller than that of Al4SiC4 (16%), while the linear compressibility along a- or b-axis direction showed better anti-deformation behavior than that of along c-axis direction. The peak heights of total density of state (TDOS) and partial density of state (PDOS) curves of Al4Si2C5 are slightly lowered with forced high pressure. Meanwhile, the mechanical properties of Al4Si2C5-like elastic constants and elastic moduli accelerate with the pressure increasing from 0 GPa to 40 GPa; the thermal expansion coefficient α increases rapidly at lower temperature and this tendency gradually approaches a linear increase when the temperature is above 1000 K. At particular temperature, α decreases continuously with the pressure accelerating. Heat capacity at constant volume (CV) with pressure was also evaluated, the results displayed that CV is sensitive with the temperature rather than the pressure. The elastic anisotropy and Debye temperature with pressure were successfully obtained and discussed.
REACTOR GROUT THERMAL PROPERTIES
Steimke, J.; Qureshi, Z.; Restivo, M.; Guerrero, H.
2011-01-28
Savannah River Site has five dormant nuclear production reactors. Long term disposition will require filling some reactor buildings with grout up to ground level. Portland cement based grout will be used to fill the buildings with the exception of some reactor tanks. Some reactor tanks contain significant quantities of aluminum which could react with Portland cement based grout to form hydrogen. Hydrogen production is a safety concern and gas generation could also compromise the structural integrity of the grout pour. Therefore, it was necessary to develop a non-Portland cement grout to fill reactors that contain significant quantities of aluminum. Grouts generate heat when they set, so the potential exists for large temperature increases in a large pour, which could compromise the integrity of the pour. The primary purpose of the testing reported here was to measure heat of hydration, specific heat, thermal conductivity and density of various reactor grouts under consideration so that these properties could be used to model transient heat transfer for different pouring strategies. A secondary purpose was to make qualitative judgments of grout pourability and hardened strength. Some reactor grout formulations were unacceptable because they generated too much heat, or started setting too fast, or required too long to harden or were too weak. The formulation called 102H had the best combination of characteristics. It is a Calcium Alumino-Sulfate grout that contains Ciment Fondu (calcium aluminate cement), Plaster of Paris (calcium sulfate hemihydrate), sand, Class F fly ash, boric acid and small quantities of additives. This composition afforded about ten hours of working time. Heat release began at 12 hours and was complete by 24 hours. The adiabatic temperature rise was 54 C which was within specification. The final product was hard and displayed no visible segregation. The density and maximum particle size were within specification.
NASA Astrophysics Data System (ADS)
Tang, Chun-Mei; Deng, Kai-Ming; Chen, Xuan; Xiao, Chuan-Yun; Liu, Yu-Zhen; Li, Qun-Xiang
2009-07-01
The structural and electronic properties of the 0.5 ML-terminated allyl mercaptan (ALM)/Si(100)-(2 × 1) surface are studied using the density functional method. The calculated absorption energy of the ALM molecule on the 0.5 ML-terminated ALM/Si(100)-(2 × 1) surface is 3.36 eV, implying that adsorption is strongly favorable. The electronic structure calculations show that the ALM/Si(100)-(2 × 1), the clean Si(100)-(2 × 1), and the fully-terminated H/Si(100)-(2 × 1) surfaces have the nature of an indirect band gap semiconductor. The highest occupied molecular orbital is dominated by the ALM, confirming the mechanism proposed by Hossain for its chain reaction.
1981-12-01
24 23. Effect of texture and density on thermal conductivity and on thermal diffusivity...take place uniformly rough idea of their domains of influence as related to throughout the porous medium (e.g. see De Vries 1958). soil texture and... texture " is formed by a reconsti- soitt coitact effects by deriving parameters atyd coef- tuion of the entire soil systedtb with a ecange in its ficients
Vesta surface thermal properties map
Capria, Maria Teresa; Tosi, F.; De Santis, Maria Cristina; Capaccioni, F.; Ammannito, E.; Frigeri, A.; Zambon, F; Fonte, S.; Palomba, E.; Turrini, D.; Titus, T.N.; Schroder, S.E.; Toplis, M.J.; Liu, J.Y.; Combe, J.-P.; Raymond, C.A.; Russell, C.T.
2014-01-01
The first ever regional thermal properties map of Vesta has been derived from the temperatures retrieved by infrared data by the mission Dawn. The low average value of thermal inertia, 30 ± 10 J m−2 s−0.5 K−1, indicates a surface covered by a fine regolith. A range of thermal inertia values suggesting terrains with different physical properties has been determined. The lower thermal inertia of the regions north of the equator suggests that they are covered by an older, more processed surface. A few specific areas have higher than average thermal inertia values, indicative of a more compact material. The highest thermal inertia value has been determined on the Marcia crater, known for its pitted terrain and the presence of hydroxyl in the ejecta. Our results suggest that this type of terrain can be the result of soil compaction following the degassing of a local subsurface reservoir of volatiles.
NASA Astrophysics Data System (ADS)
Hiadsi, S.; Bouafia, H.; Sahli, B.; Abidri, B.; Bouaza, A.; Akriche, A.
2016-08-01
This study presents a theoretical prediction of the structural, mechanical, electronic and thermal properties of the zinc-based Perovskites (AgZnF3 and KZnF3) within the framework of Density Functional Theory (DFT) using All-electron self consistent Full Potential Augmented Plane Waves plus local orbital FP-(L)APW + lo method. To make our work comparable and reliable, several functional were used for the exchange-correlation potential. Also, this study intends to provide a basis and an improvement for updating either the values already predicted by other previous work (by using obsolete functional) or to predict them for the first time. GGA-PBE and GGA-PBEsol were used to predict the structural properties of AgZnF3 and KZnF3 Perovskites such as lattice parameter, bulk modulus and its pressure derivative and the cohesive energy. For these properties, the found values are in very good agreement; also those found by GGA-PBEsol are closer to other available previous and experimental results. The electronic properties of these materials are investigated and compared to provide a consolidated prediction by using the modified Becke Johnson potential TB-mBJ with other functional; the values found by this potential are closer to the available proven results and show that these materials exhibit an indirect gap from R to Γ point. The charge densities plot for [110] direction and QTAIM (Quantum Theory of Atoms in Molecules) theory indicate that ionic character is predominate for (K, Ag, Zn)sbnd F bonds. Finally, the effect of temperature and pressure on the unit cell volume, the heat capacity CV and entropy were studied using the quasi-harmonic Debye model.
Program calculation of thermodynamic properties
NASA Astrophysics Data System (ADS)
Gill, Walter; Filho, Fernando Fachini; Ribeirodeoliveira, Ronaldo
1986-12-01
The determination of the thermodynamic properties are examined through the basic equations such as: state equation (Beattie-Bridgeman Form), saturation pressure equation, specific heat constant pressure or constant volume equation, and specific volume or density of liquid equation.
Properties of air-aluminum thermal plasmas
NASA Astrophysics Data System (ADS)
Cressault, Y.; Gleizes, A.; Riquel, G.
2012-07-01
We present the calculation and the main results of the properties of air-aluminum thermal plasmas, useful for complete modelling of arc systems involving aluminum contacts. The properties are calculated assuming thermal equilibrium and correspond to the equilibrium composition, thermodynamic functions, transport coefficients including diffusion coefficients and net emission coefficient representing the divergence of the radiative flux in the hottest plasma regions. The calculation is developed in the temperature range between 2000 and 30 000 K, for a pressure range from 0.1 to 1 bar and for several metal mass proportions. As in the case of other metals, the presence of aluminum vapours has a strong influence on three properties at intermediate temperatures: the electron number density, the electrical conductivity and the net emission coefficient. Some comparisons with other metal vapour (Cu, Fe and Ag) properties are made and show the original behaviour for Al-containing mixtures: mass density at high temperatures is low due to the low Al atomic mass; high electrical conductivity at T < 10 000 K due to low ionization potential (around 2 V less for Al than for the other metals); very strong self-absorption of ionized aluminum lines, leading to a net emission coefficient lower than that of pure air when T > 10 000 K, in contrast to copper or iron radiation.
Direct-Semidirect Thermal Neutron Capture Calculations
Arbanas, G; Dietrich, F S; Kerman, A K
2005-12-20
A method for computing direct-semidirect (DSD) neutron radiative capture is presented and applied to thermal neutron capture on {sup 19}F, {sup 27}Al, {sup 28,29.30}Si, {sup 35,37}Cl, {sup 39,41}K, {sup 56}Fe, and {sup 238}U, in support of data evaluation effort at the O.R.N.L. The DSD method includes both direct and semidirect capture; the latter is a core-polarization term in which the giant dipole resonance is formed. We study the effects of a commonly used ''density'' approximation to the EM operator and find it to be unsatisfactory for the nuclei considered here. We also study the magnitude of semidirect capture relative to the pure direct capture. Furthermore, we compare our results with those obtained from another direct capture code (Tedca [17]). We also compare our results with those obtained from analytical expression for external capture derived by Lane and Lynn [3], and its extension to include internal capture [7]. To estimate the effect of nuclear deformation on direct capture, we computed direct thermal capture on {sup 238}U with and without imposition of spherical symmetry. Direct capture for a spherically symmetric {sup 238}U was approximately 6 mb, while a quadrupole deformation of 0.215 on the shape of {sup 238}U lowers this cross section down to approximately 2 mb. This result suggests that effects of nuclear deformation on direct capture warrant a further study. We also find out that contribution to the direct capture on {sup 238}U from the nuclear interior significantly cancels that coming from the exterior region, and hence both contributions must be taken into account. We reproduced a well known discrepancy between the computed and observed branching ratios in {sup 56}Fe(n,{gamma}). This will lead us to revisit the concept of doorway states in the particle-hole model.
Method for measuring thermal properties using a long-wavelength infrared thermal image
Walker, Charles L.; Costin, Laurence S.; Smith, Jody L.; Moya, Mary M.; Mercier, Jeffrey A.
2007-01-30
A method for estimating the thermal properties of surface materials using long-wavelength thermal imagery by exploiting the differential heating histories of ground points in the vicinity of shadows. The use of differential heating histories of different ground points of the same surface material allows the use of a single image acquisition step to provide the necessary variation in measured parameters for calculation of the thermal properties of surface materials.
NASA Technical Reports Server (NTRS)
Hendricks, R. C.; Baron, A. K.; Peller, I. C.
1975-01-01
A FORTRAN IV subprogram called GASP is discussed which calculates the thermodynamic and transport properties for 10 pure fluids: parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. The pressure range is generally from 0.1 to 400 atmospheres (to 100 atm for helium and to 1000 atm for hydrogen). The temperature ranges are from the triple point to 300 K for neon; to 500 K for carbon monoxide, oxygen, and fluorine; to 600 K for methane and nitrogen; to 1000 K for argon and carbon dioxide; to 2000 K for hydrogen; and from 6 to 500 K for helium. GASP accepts any two of pressure, temperature and density as input conditions along with pressure, and either entropy or enthalpy. The properties available in any combination as output include temperature, density, pressure, entropy, enthalpy, specific heats, sonic velocity, viscosity, thermal conductivity, and surface tension. The subprogram design is modular so that the user can choose only those subroutines necessary to the calculations.
Burnham, A K; Weese, R K; Wang, R; Kwok, Q M; Jones, D G
2005-03-30
Much effort has been devoted to an ongoing search for more powerful, safer and environmentally friendly explosives. Since it was developed in the late 1990s, 1,1-diamino-2,2-dinitroethene (FOX-7), with lower sensitivity and comparable performance to RDX, has received increasing interest. Preliminary results on the physical and chemical characterization of FOX-7 have shown that it possesses good thermal and chemical stability. It is expected that FOX-7 will be a new important explosive ingredient in high performance, insensitive munition (IM) explosives. One of the major focuses in research on this novel energetic material is a study of its thermal properties. Oestmark et al have reported that DSC curves exhibit two minor endothermic peaks as well as two major exothermic peaks. Two endothermic peaks at {approx}116 and {approx}158 C suggest the presence of two solid-solid phase transitions. A third phase change below 100 C has also been reported based on a X-ray powder diffraction (XPD) study. The shapes, areas and observed temperatures of the two decomposition peaks at {approx}235 C and {approx}280 C vary with different batches and sources of the sample, and occasionally these two peaks are merged into one. The factors leading to this variation and a more complete investigation are in progress. Our laboratories have been interested in the thermal properties of energetic materials characterized by means of various thermal analysis techniques. This paper will present our results for the thermal behavior of FOX-7 including the phase changes, decomposition, kinetic analysis and the decomposition products using DSC, TG, ARC (Accelerating Rate Calorimetry), HFC (Heat Flow Calorimetry) and simultaneous TGDTA-FTIR (Fourier Transform Infrared Spectroscopy) Spectroscopy-MS (Mass) measurements.
Thermodynamic Properties of Rutile (TiO2) Within the Phonon Calculations
NASA Astrophysics Data System (ADS)
Kangarlou, Haleh; Abdollahi, Arash
2016-11-01
Full phonon calculations have been performed to estimate the thermal properties of rutile (titanium dioxide). Calculations have been carried out using the pseudo-potential method within the local density approximation. Thermodynamic properties including the thermal expansion, thermal expansion coefficient, heat capacity and entropy were calculated as a function of temperature in the framework of quasi-harmonic approximation. Also, to compare the results with the results of other approaches, we apply Debye-Slater and Debye-Gruneisen approaches with the same parameters for electronic calculations. It is found that the phonon calculations provide more accurate estimates in comparison with the other two models.
Thermal conductance of one-dimensional materials calculated with typical lattice models
NASA Astrophysics Data System (ADS)
Zhang, Chunyi; Kang, Wei; Wang, Jianxiang
2016-11-01
We show through calculations on typical lattice models that thermal conductance σ can well describe the near-equilibrium thermal transport property of one-dimensional materials of finite length, which presents a situation often met in the application of nanoscale devices. The σ generally contains contributions from the material itself and those from the thermal reservoirs. The intrinsic σ of the material, i.e., the one with the fewest external influences, can be efficiently calculated with the help of the "blackbody"-like nonreflective thermal reservoir, either through the nonequilibrium method or through the Green-Kubo-type formula. σ thus calculated would be helpful to guide the design of thermal management and heat control in nanoscale devices.
NASA Astrophysics Data System (ADS)
Gordon, S.; McBride, B.; Zeleznik, F. J.
1984-10-01
An addition to the computer program of NASA SP-273 is given that permits transport property calculations for the gaseous phase. Approximate mixture formulas are used to obtain viscosity and frozen thermal conductivity. Reaction thermal conductivity is obtained by the same method as in NASA TN D-7056. Transport properties for 154 gaseous species were selected for use with the program.
NASA Technical Reports Server (NTRS)
Gordon, S.; Mcbride, B.; Zeleznik, F. J.
1984-01-01
An addition to the computer program of NASA SP-273 is given that permits transport property calculations for the gaseous phase. Approximate mixture formulas are used to obtain viscosity and frozen thermal conductivity. Reaction thermal conductivity is obtained by the same method as in NASA TN D-7056. Transport properties for 154 gaseous species were selected for use with the program.
Benchmark calculations of thermal reaction rates. I - Quantal scattering theory
NASA Technical Reports Server (NTRS)
Chatfield, David C.; Truhlar, Donald G.; Schwenke, David W.
1991-01-01
The thermal rate coefficient for the prototype reaction H + H2 yields H2 + H with zero total angular momentum is calculated by summing, averaging, and numerically integrating state-to-state reaction probabilities calculated by time-independent quantum-mechanical scattering theory. The results are very carefully converged with respect to all numerical parameters in order to provide high-precision benchmark results for confirming the accuracy of new methods and testing their efficiency.
Refinement of thermal imager minimum resolvable temperature difference calculating method
NASA Astrophysics Data System (ADS)
Kolobrodov, V. G.; Mykytenko, V. I.
2015-11-01
Calculating methods, which accurately predict minimum resolvable temperature difference (MRTD), are of significant interest for many years. The article deals with improvement the accuracy of determining the thermal imaging system MRTD by elaboration the visual perception model. We suggest MRTD calculating algorithm, which is based on a reliable approximation of the human visual system modulation transfer function (MTF) proposed by N. Nill. There was obtained a new expression for the bandwidth evaluation, which is independent of angular size of the Foucault bar target.
Point kinetics calculations with fully coupled thermal fluids reactivity feedback
Zhang, H.; Zou, L.; Andrs, D.; Zhao, H.; Martineau, R.
2013-07-01
The point kinetics model has been widely used in the analysis of the transient behavior of a nuclear reactor. In the traditional nuclear reactor system safety analysis codes such as RELAP5, the reactivity feedback effects are calculated in a loosely coupled fashion through operator splitting approach. This paper discusses the point kinetics calculations with the fully coupled thermal fluids and fuel temperature feedback implemented into the RELAP-7 code currently being developed with the MOOSE framework. (authors)
A Method for Calculating Viscosity and Thermal Conductivity of a Helium-Xenon Gas Mixture
NASA Technical Reports Server (NTRS)
Johnson, Paul K.
2006-01-01
A method for calculating viscosity and thermal conductivity of a helium-xenon (He-Xe) gas mixture was employed, and results were compared to AiResearch (part of Honeywell) analytical data. The method of choice was that presented by Hirschfelder with Singh's third-order correction factor applied to thermal conductivity. Values for viscosity and thermal conductivity were calculated over a temperature range of 400 to 1200 K for He-Xe gas mixture molecular weights of 20.183, 39.94, and 83.8 kg/kmol. First-order values for both transport properties were in good agreement with AiResearch analytical data. Third-order-corrected thermal conductivity values were all greater than AiResearch data, but were considered to be a better approximation of thermal conductivity because higher-order effects of mass and temperature were taken into consideration. Viscosity, conductivity, and Prandtl number were then compared to experimental data presented by Taylor.
Recommended radiative property data for Venusian entry calculations
NASA Technical Reports Server (NTRS)
Jones, J. J.; Boughner, R. E.; Haggard, K. V.; Nealy, J. E.; Schryer, D. R.; Zoby, E. V.
1974-01-01
A compilation of experimental and calculated data on the radiative properties species important in Venusian entry is presented. Molecular band systems, atomic lines, free-bound, and free-free continua are considered for the principal radiating species of shock heated carbon dioxide. A limited amount of data pertinent to the species in the ablation layer is also included. The assumption is made that the Venus atmosphere so closely approximates pure CO2 that the inviscid layer radiation is due almost entirely to thermally excited CO2. The only exception is the inclusion of data on the Violet band system of CN. Recommendations are made as to best property values for radiative heating calculations. A review of the basic equations and the relationships of the various emission-absorption gas porperties is also included.
Thermal conductivity calculations of crystalline quartz from the BKS potential
NASA Astrophysics Data System (ADS)
Yoon, Young-Gui; Car, Roberto; Srolovitz, David J.; Scandolo, Sandro
2003-03-01
We present thermal conductivity calculations from the classical BKS potential[1]. Following a velocity rescaling method for a constant heat flux proposed by P. Jund and R. Jullien[2], thermal conductivity as a heat flux to temperature gradient ratio is directly calculated in periodic simulation cells. Our calculations in a wide temperature range at which crystalline quartz exists are consistent with the experimental trend[3]. The conductivity decreases with temperature in the alpha-quartz regime, and increases after the phase transition to beta-quartz. The temperature dependence is rather small in the beta-quartz regime. [1] B. W. H. van Beest, G. J. Kramer, and R. A. van Santen, Phy. Rev. Lett. 64, 1995 (1990). [2] P. Jund, and R. Jullien, Phy. Rev. B 59, 13707 (1999). [3] H. Kanamori, N. Fujii, and H. Mizutani, J. Geophys. Res. 73, 595 (1968).
Anisotropic intrinsic lattice thermal conductivity of borophane from first-principles calculations.
Liu, Gang; Wang, Haifeng; Gao, Yan; Zhou, Jian; Wang, Hui
2017-01-25
Borophene (boron sheet) as a new type of two-dimensional (2D) material was grown successfully recently. Unfortunately, the structural stability of freestanding borophene is still an open issue. Theoretical research has found that full hydrogenation can remove such instability, and the product is called borophane. In this paper, using first-principles calculations we investigate the lattice dynamics and thermal transport properties of borophane. The intrinsic lattice thermal conductivity and the relaxation time of borophane are investigated by solving the phonon Boltzmann transport equation (BTE) based on first-principles calculations. We find that the intrinsic lattice thermal conductivity of borophane is anisotropic, as the higher value (along the zigzag direction) is about two times of the lower one (along the armchair direction). The contributions of phonon branches to the lattice thermal conductivities along different directions are evaluated. It is found that both the anisotropy of thermal conductivity and the different phonon branches which dominate the thermal transport along different directions are decided by the group velocity and the relaxation time of phonons with very low frequency. In addition, the size dependence of thermal conductivity is investigated using cumulative thermal conductivity. The underlying physical mechanisms of these unique properties are also discussed in this paper.
NASA Technical Reports Server (NTRS)
Jenkins, J. M.; Taylor, A. H.; Sakata, I. F.
1985-01-01
A hybrid spar of titanium with an integrally brazed composite, consisting of an aluminum matrix reinforced with boron-carbide-coated fibers, was heated in an oven and the resulting thermal stresses were measured. Uniform heating of the spar in an oven resulted in thermal stresses arising from the effects of dissimilar materials and anisotropy of the metal matrix composite. Thermal stresses were calculated from a finite element structural model using anisotropic material properties deduced from constituent properties and rules of mixtures. Comparisons of calculated thermal stresses with measured thermal stresses on the spar are presented. It was shown that failure to account for anisotropy in the metal matrix composite elements would result in large errors in correlating measured and calculated thermal stresses. It was concluded that very strong material characterization efforts are required to predict accurate thermal stresses in anisotropic composite structures.
Thermal Properties of Bazhen fm. Sediments from Thermal Core Logging
NASA Astrophysics Data System (ADS)
Spasennykh, Mikhail; Popov, Evgeny; Popov, Yury; Chekhonin, Evgeny; Romushkevich, Raisa; Zagranovskaya, Dzhuliya; Belenkaya, Irina; Zhukov, Vladislav; Karpov, Igor; Saveliev, Egor; Gabova, Anastasia
2016-04-01
The Bazhen formation (B. fm.) is the hugest self-contained source-and-reservoir continuous petroleum system covering by more than 1 mln. km2 (West Siberia, Russia). High lithological differentiation in Bazhen deposits dominated by silicic shales and carbonates accompanied by extremely high total organic carbon values (of up to 35%), pyrite content and brittle mineralogical composition deteriorate standard thermal properties assessment for low permeable rocks. Reliable information of unconventional system thermal characteristics is the necessary part of works such as modelling of different processes in reservoir under thermal EOR for accessing their efficiency, developing and optimizing design of the oil recovery methods, interpretation of the well temperature logging data and for the basin petroleum modelling. A unique set of data including thermal conductivity, thermal diffusivity, volumetric heat capacity, thermal anisotropy for the B.fm. rocks was obtained from thermal core logging (high resolution continuous thermal profiling) on more than 4680 core samples (2000 of B.fm. samples are among) along seven wells for four oil fields. Some systematic peculiarities of the relation between thermal properties of the B.fm. rocks and their mineralogical composition, structural and texture properties were obtained. The high-resolution data are processed jointly with the standard petrophysical logging that allowed us to provide better separation of the formation. The research work was done with financial support of the Russian Ministry of Education and Science (unique identification number RFMEFI58114X0008).
Thermal properties of defective fullerene
NASA Astrophysics Data System (ADS)
Li, Jian; Zheng, Dong-Qin; Zhong, Wei-Rong
2016-09-01
We have investigated the thermal conductivity of defective fullerene (C60) by using the nonequilibrium molecular dynamics (MD) method. It is found that the thermal conductivity of C60 with one defect is lower than the thermal conductivity of perfect C60. However, double defects in C60 have either positive or negative influence on the thermal conductivity, which depends on the positions of the defects. The phonon spectra of perfect and defective C60 are also provided to give corresponding supports. Our results can be extended to long C60 chains, which is helpful for the thermal management of C60.
Thermal Properties of Whispering Gallery Mode Resonators
2014-12-22
F01m 298 (Rev 8/98) Prescribed by ANSI Std. Z39.18 ABSTRACT Number of Papers published in peer-reviewed journals: Thermal Properties of Whispering...Gallery Mode Resonators Report Title In this project, we studied the thermal properties of ultra-high-quality whispering-gallery-mode microtoroid...resonators. More specifically, we measured the thermal relaxation time of the resonator to estimate the response time of the resonator based infrared (IR
Shale: Measurement of thermal properties
Gilliam, T.M.; Morgan, I.L.
1987-07-01
Thermal conductivity and heat capacity measurements were made on samples of Devonian shale, Pierre shale, and oil shale from the Green River Formation. Thermal expansion measurements were made on selected samples of Devonian shale. Measurements were obtained over the temperature range of ambient to 473 K. Average values for thermal conductivity and heat capacity for the samples studied were within two standard deviations of all data over this temperature range. 15 refs., 12 figs., 4 tabs.
Ab initio theory of thermal properties of germanane
NASA Astrophysics Data System (ADS)
Heine, Matthew; Lindsay, Lucas; Carrete, Jesús; Mingo, Natalio; Hellman, Olle; Broido, David
Germanane(GeH) is a germanium based hydrogen-terminated multi-layered graphane analogue semiconductor, which may be a promising thermoelectric due to its high electron mobility and the capability to tune its transport properties. We have performed first principles calculations of the thermal properties of germanane. Harmonic and anharmonic interatomic force constants are calculated within the framework of density functional theory, from which phonon dispersions, specific heat, thermal expansion are obtained. The phonon Boltzmann equation is solved to obtain the lattice thermal conductivity. The disparity in constituent masses in GeH gives phonon modes that are distinctly Ge or H in character and causes the specific heat not to saturate until much higher temperatures than in bulk Ge. Weak interlayer bonding and strong phonon-phonon scattering result in highly anisotropic and quite low intrinsic lattice thermal conductivity compared to Ge.
Numerical calculation of thermal effect on cavitation in cryogenic fluids
NASA Astrophysics Data System (ADS)
Shi, Suguo; Wang, Guoyu
2012-11-01
A key design issue related to the turbopump of the rocket engine is that cavitation occurs in cryogenic fluids when the fluid pressure is lower than the vapor pressure at a local thermodynamic state. Cavitation in cryogenic fluids generates substantial thermal effects and strong variations in fluid properties, which in turn alter the cavity characteristics. To date, fewer investigate the thermal effect on cavitation in cryogenic fluids clearly by the numerical methods due to the difficulty of the heat transfer in the phase change process. In order to study the thermal effect on cavitation in cryogenic fluid, computations are conducted around a 2D quarter caliber hydrofoil in liquid nitrogen and hydrogen respectively by implementing modified Merkle cavitation model, which accounts for the energy balance and variable thermodynamic properties of the fluid. The numerical results show that with the thermal effect, the vapour content in constant location decreases, the cavity becomes more porous and the interface becomes less distinct which shows increased spreading while getting shorter in length. In the cavity region, the temperature around the cavity depresses due to absorb the evaporation latent heat and the saturation pressure drops. When the vapour volume fraction is higher, the temperature depression and pressure depression becomes larger. It is also observed that a slight temperature rise is found above the reference fluid temperature at the cavity rear end attributed to the release of latent heat during the condensation process. When the fluid is operating close to its critical temperature, thermal effects on cavitation are more obviously in both the liquid nitrogen and hydrogen. The thermal effect on cavitation in liquid hydrogen is more distinctly compared with that in liquid nitrogen due to the density ratio, vapour pressure and other variable properties of the fluid. The investigation provides aid for the design of the cryogenic pump of the liquid rocket.
Thermal calculations pertaining to experiments in the Yucca Mountain Exploratory Shaft
Montan, D.N.
1986-03-01
A series of thermal calculations have been presented that appear to satisfy the needs for design of the Yucca Mountain Exploratory Shaft Tests. The accuracy of the modeling and calculational techniques employed probably exceeds the accuracy of the thermal properties used. The rather close agreement between simple analytical methods (the PLUS Family) and much more complex methods (TRUMP) suggest that the PLUS Family might be appropriate during final design to model, in a single calculation, the entire test array and sequence. Before doing further calculations it is recommended that all available thermal property information be critically evaluated to determine "best" values to be used for conductivity and saturation. Another possibility is to design one or more of the test sequences to approximately duplicate the early phase of Heater Test 1. In that experiment an unplanned power outage for about two days that occurred a week into the experiment gave extremely useful data from which to determine the conductivity and diffusivity. In any case we urge that adequate, properly calibrated instrumentation with data output available on a quasi-real time basis be installed. This would allow us to take advantage of significant power changes (planned or not) and also help "steer" the tests to desired temperatures. Finally, it should be kept in mind that the calculations presented here are strictly thermal. No hydrothermal effects due to liquid and vapor pressures have been considered.
Thermal inertia properties of autoclaved aerated concrete
Ropelewski, L.; Neufeld, R.D.
1999-08-01
Autoclaved aerated concrete (AAC) is a lightweight, porous concrete with advanced thermal properties. AAC is unique among construction materials in combining excellent thermal resistance and thermal inertia. Generally, low-density construction materials do not provide good thermal inertia, while heavier ones commonly have poor thermal resistance. Five different 10.2 cm (4 in.) AAC samples made from US electric utility fly ash as the silica source, along with three 10.2 cm (4 in.) conventional building material specimens, were tested for thermal inertia properties. Three primary issues addressed by these experiments were: (1) to develop and compare AAC thermal inertia to conventional building materials; (2) to document differences in thermal inertia characteristics of the AAC blocks produced by the various utilities; and (3) to determine if a periodic heat flow model using the thermal inertia approach adequately predicts the observed thermal inertia parameters of a material. A theoretical periodic heat flow model in the literature for thermal inertia did an adequate job of predicting the observed thermal inertia parameters for the AAC and conventional construction samples.
NASA Astrophysics Data System (ADS)
Guo, Xingye; Lu, Zhe; Jung, Yeon-Gil; Li, Li; Knapp, James; Zhang, Jing
2016-06-01
Lanthanum zirconate (La2Zr2O7) coatings are newly proposed thermal barrier coating (TBC) systems which exhibit lower thermal conductivity and potentially higher thermal stability compared to other traditional thermal barrier systems. In this work, La2Zr2O7 and 8 wt pct yttria stabilized zirconia (8YSZ) single-layer and double-layer TBC systems were deposited using the air plasma spray technique. Thermal properties of the coatings were measured. Furnace heat treatment and jet engine thermal shock tests were implemented to evaluate coating performance during thermal cycling. The measured average thermal conductivity of porous La2Zr2O7 coating ranged from 0.59 to 0.68 W/m/K in the temperature range of 297 K to 1172 K (24 °C to 899 °C), which was approximately 25 pct lower than that of porous 8YSZ (0.84 to 0.87 W/m/K) in the same temperature range. The coefficients of thermal expansion values of La2Zr2O7 were approximately 9 to 10 × 10-6/K from 400 K to 1600 K (127 °C to 1327 °C), which were about 10 pct lower than those of porous 8YSZ. The double-layer coating system consisting of the porous 8YSZ and La2Zr2O7 layers had better thermal shock resistance and thermal cycling performance than those of single-layer La2Zr2O7 coating and double-layer coating with dense 8YSZ and La2Zr2O7 coatings. This study suggests that porous 8YSZ coating can be employed as a buffer layer in La2Zr2O7-based TBC systems to improve the overall coating durability during service.
Determination of Thermal Properties of Composting Bulking Materials
Technology Transfer Automated Retrieval System (TEKTRAN)
Thermal properties of compost bulking materials affect temperature and biodegradation during the composting process. Well determined thermal properties of compost feedstocks will therefore contribute to practical thermodynamic approaches. Thermal conductivity, thermal diffusivity, and volumetric hea...
Differential pressure corrections calculated for a tank thermal expansion experiment
Jones, F.E.; Crawford, J.M.
1997-12-31
The data from a tank thermal expansion experiment were treated by applying corrections to bubble tube differential pressure measurements at an initial temperature. The tank had a capacity of 3.55 m{sup 3} and an internal height of about 0.90 m. Water was used as the experimental fluid for four runs. Minimum temperature for the runs ranged from 13.5 C to 37.6 C; maximum temperatures ranged from 48.6 C to 70.4 C. For each run, using an equation appropriate for the ANSI N15.19 tank volume calibration standard, differential pressure was calculated at various temperatures from measured differential pressure at an initial temperature. The calculated differential pressure was compared to the measured differential pressure. The agreement between calculated and measured differential pressure was excellent.
Thermal properties of UO2 single crystal
NASA Astrophysics Data System (ADS)
Gofryk, K.; Du, S.; Andersson, A. D.; Stanek, C. R.; Schulze, R.; Safarik, D.; Mihaila, B.; Lashley, J. C.; Smith, J. L.
2013-03-01
For decades UO2 has been the most widely studied actinide oxide because of its technological importance as fuel material for nuclear reactors. Therefore there is a large interest in understanding its thermal, transport and thermodynamic properties. We present recent experimental results for the thermal conductivity and thermal expansion of high quality UO2 single crystal, obtained for different crystallographic directions, and compare with results of molecular dynamics simulations. We will discuss the implications of this study.
Thermal to electricity conversion using thermal magnetic properties
West, Phillip B [Idaho Falls, ID; Svoboda, John [Idaho Falls, ID
2010-04-27
A system for the generation of Electricity from Thermal Energy using the thermal magnetic properties of a Ferromagnetic, Electrically Conductive Material (FECM) in one or more Magnetic Fields. A FECM is exposed to one or more Magnetic Fields. Thermal Energy is applied to a portion of the FECM heating the FECM above its Curie Point. The FECM, now partially paramagnetic, moves under the force of the one or more Magnetic Fields. The movement of the FECM induces an electrical current through the FECM, generating Electricity.
Thermal properties of ethylene glycol aqueous solutions.
Baudot, A; Odagescu, V
2004-06-01
Preventing ice crystallization by transforming liquids into an amorphous state, vitrification can be considered as the most suitable technique allowing complex tissues, and organs cryopreservation. This process requires the use of rapid cooling rates in the presence of cryoprotective solutions highly concentrated in antifreeze compounds, such as polyalcohols. Many of them have already been intensively studied. Their glass forming tendency and the stability of their amorphous state would make vitrification a reality if their biological toxicity did not reduce their usable concentrations often below the concentrations necessary to vitrify organs under achievable thermal conditions. Fortunately, it has been shown that mixtures of cryoprotectants tend to reduce the global toxicity of cryoprotective solutions and various efficient combinations have been proposed containing ethanediol. This work reports on the thermal properties of aqueous solutions with 40, 43, 45, 48, and 50% (w/w) of this compound measured by differential scanning calorimetry. The glass forming tendency and the stability of the amorphous state are evaluated as a function of concentration. They are given by the critical cooling rates v(ccr)above which ice crystallization is avoided, and the critical warming rates v(cwr) necessary to prevent ice crystallization in the supercooled liquid state during rewarming. Those critical rates are calculated using the same semi-empirical model as previously. This work shows a strong decrease of averaged critical cooling and warming rates when ethanediol concentration increases, V(ccr) and V(cwr) = 1.08 x 10 (10) K/min for 40% (w/w) whereas V(ccr) = 11 and V(cwr) = 853 K/min for 50% (w/w). Those results are compared with the corresponding properties of other dialcohols obtained by the same method. Ethylene glycol efficiency is between those of 1,2-propanediol and 1,3-propanediol.
Thermal characterization and properties of a copper-diamond composite
Yang, Pin; Chavez, Thomas P.; DiAntonio, Christopher Brian; Coker, Eric Nicholas
2014-09-01
The thermal properties of a commercial copper-diamond composite were measured from below -50°C to above 200°C. The results of thermal expansion, heat capacity, and thermal diffusivity were reported. These data were used to calculate the thermal conductivity of the composite as a function of temperature in the thickness direction. These results are compared with estimated values based on a simple mixing rule and the temperature dependence of these physical properties is represented by curve fitting equations. These fitting equations can be used for thermal modeling of practical devices/systems at their operation temperatures. The results of the mixing rule showed a consistent correlation between the amount of copper and diamond in the composite, based on density, thermal expansion, and heat capacity measurements. However, there was a disparity between measured and estimated thermal diffusivity and thermal conductivity. These discrepancies can be caused by many intrinsic material issues such as lattice defects and impurities, but the dominant factor is attributed to the large uncertainty of the interfacial thermal conductance between diamond and copper.
Sumi, Chikayoshi; Yanagimura, Hiroyuki
2007-05-21
We report robust noninvasive techniques for reconstructing the thermal properties of living tissues, such as thermal conductivity, thermal capacity and thermal diffusivity, for the diagnosis, monitoring and planning of thermal treatments. Internal temperature distributions can be measured using ultrasonic imaging or magnetic resonance imaging. Provided that the reference thermal properties are given in the region of interest as initial conditions, by solving bioheat transfer equations as simultaneous first-order partial differential equations having temperature distributions as inhomogeneous coefficients, we can determine thermal property distributions. A novel regularized numerical solution is also presented to realize useful, unique, stable reconstructions of the thermal property distributions. To verify the feasibility of the numerical solution, simulations and ultrasonic phantom experiments are conducted. The reconstruction of perfusion by blood flow and thermal source/sink by this approach is also addressed.
Thermal properties of lithium sulphate
NASA Astrophysics Data System (ADS)
Suleiman, B. M.; Gustavsson, M.; Karawacki, E.; Lundén, A.
1997-09-01
The thermal conductivity and diffusivity of lithium sulphate have been measured simultaneously, using the transient plane source technique over the temperature range 300 - 900 K. The thermal conductivity decreases slowly up to about 640 K, whereupon a distinct rise occurs, indicating the onset of a pre-transitional behaviour, which causes a continuous growth of the conductivity up to the structural phase transition at 851 K, whereupon a very sharp increase occurs. A similar behaviour has been observed for the thermal diffusivity, for which a very sharp dip occurs at the transition point due to the exceptionally large transition enthalpy. The pre-transitional behaviour of heat transport is associated with the librational disorder of the sulphate anions known from Raman scattering studies of both phases (and neutron scattering from the cubic phase), whereas the translational disorder of lithium cations is of hardly any importance. It is thus possible to link the `paddle-wheel' concept of ion migration in the cubic phase to the enhancement of heat transport observed in the `pre-transition' region, as well as to the large difference in heat-transport rates between the monoclinic and cubic phases.
NASA Technical Reports Server (NTRS)
Haskins, Justin; Kinaci, Alper; Sevik, Cem; Cagin, Tahir
2012-01-01
It is widely known that graphene and many of its derivative nanostructures have exceedingly high reported thermal conductivities (up to 4000 W/mK at 300 K). Such attractive thermal properties beg the use of these structures in practical devices; however, to implement these materials while preserving transport quality, the influence of structure on thermal conductivity should be thoroughly understood. For graphene nanostructures, having average phonon mean free paths on the order of one micron, a primary concern is how size influences the potential for heat conduction. To investigate this, we employ a novel technique to evaluate the lattice thermal conductivity from the Green-Kubo relations and equilibrium molecular dynamics in systems where phonon-boundary scattering dominates heat flow. Specifically, the thermal conductivities of graphene nanoribbons and carbon nanotubes are calculated in sizes up to 3 microns, and the relative influence of boundary scattering on thermal transport is determined to be dominant at sizes less than 1 micron, after which the thermal transport largely depends on the quality of the nanostructure interface. The method is also extended to carbon nanostructures (fullerenes) where phonon confinement, as opposed to boundary scattering, dominates, and general trends related to the influence of curvature on thermal transport in these materials are discussed.
Huang, Jianhua
2012-07-01
There are three methods for calculating thermal insulation of clothing measured with a thermal manikin, i.e. the global method, the serial method, and the parallel method. Under the condition of homogeneous clothing insulation, these three methods yield the same insulation values. If the local heat flux is uniform over the manikin body, the global and serial methods provide the same insulation value. In most cases, the serial method gives a higher insulation value than the global method. There is a possibility that the insulation value from the serial method is lower than the value from the global method. The serial method always gives higher insulation value than the parallel method. The insulation value from the parallel method is higher or lower than the value from the global method, depending on the relationship between the heat loss distribution and the surface temperatures. Under the circumstance of uniform surface temperature distribution over the manikin body, the global and parallel methods give the same insulation value. If the constant surface temperature mode is used in the manikin test, the parallel method can be used to calculate the thermal insulation of clothing. If the constant heat flux mode is used in the manikin test, the serial method can be used to calculate the thermal insulation of clothing. The global method should be used for calculating thermal insulation of clothing for all manikin control modes, especially for thermal comfort regulation mode. The global method should be chosen by clothing manufacturers for labelling their products. The serial and parallel methods provide more information with respect to the different parts of clothing.
Thermal Properties of Structural Materials Used in LWR Vessels
J. E. Daw; J. L. Rempe; D. L. Knudson
2011-01-01
High temperature material property data for structural materials used in existing Light Water Reactors (LWRs) are limited. Often, extrapolated values recommended in the literature differ significantly. To reduce uncertainties in predictions relying upon extrapolated data for LWR vessel and penetration materials, high temperature tests were completed on SA533 Grade B, Class 1 (SA533B1) low alloy steel, Stainless Steel 304 (SS304), and Inconel 600 using material property measurement systems available in the High Temperature Test Laboratory (HTTL) at the Idaho National Laboratory (INL). Properties measured include thermal expansion, specific heat capacity, and thermal diffusivity for temperatures up to 1200 °C. From these results, thermal conductivity and density were calculated. Results show that, in some cases, previously recommended values for these materials differ significantly from measured values at high temperatures.
StreamThermal: A software package for calculating thermal metrics from stream temperature data
Tsang, Yin-Phan; Infante, Dana M.; Stewart, Jana S.; Wang, Lizhu; Tingly, Ralph; Thornbrugh, Darren; Cooper, Arthur; Wesley, Daniel
2016-01-01
Improving quality and better availability of continuous stream temperature data allows natural resource managers, particularly in fisheries, to understand associations between different characteristics of stream thermal regimes and stream fishes. However, there is no convenient tool to efficiently characterize multiple metrics reflecting stream thermal regimes with the increasing amount of data. This article describes a software program packaged as a library in R to facilitate this process. With this freely-available package, users will be able to quickly summarize metrics that describe five categories of stream thermal regimes: magnitude, variability, frequency, timing, and rate of change. The installation and usage instruction of this package, the definition of calculated thermal metrics, as well as the output format from the package are described, along with an application showing the utility for multiple metrics. We believe this package can be widely utilized by interested stakeholders and greatly assist more studies in fisheries.
Martínez, G M; Rennó, N; Fischer, E; Borlina, C S; Hallet, B; de la Torre Juárez, M; Vasavada, A R; Ramos, M; Hamilton, V; Gomez-Elvira, J; Haberle, R M
2014-01-01
The analysis of the surface energy budget (SEB) yields insights into soil-atmosphere interactions and local climates, while the analysis of the thermal inertia (I) of shallow subsurfaces provides context for evaluating geological features. Mars orbital data have been used to determine thermal inertias at horizontal scales of ∼104 m2 to ∼107 m2. Here we use measurements of ground temperature and atmospheric variables by Curiosity to calculate thermal inertias at Gale Crater at horizontal scales of ∼102 m2. We analyze three sols representing distinct environmental conditions and soil properties, sol 82 at Rocknest (RCK), sol 112 at Point Lake (PL), and sol 139 at Yellowknife Bay (YKB). Our results indicate that the largest thermal inertia I = 452 J m−2 K−1 s−1/2 (SI units used throughout this article) is found at YKB followed by PL with I = 306 and RCK with I = 295. These values are consistent with the expected thermal inertias for the types of terrain imaged by Mastcam and with previous satellite estimations at Gale Crater. We also calculate the SEB using data from measurements by Curiosity's Rover Environmental Monitoring Station and dust opacity values derived from measurements by Mastcam. The knowledge of the SEB and thermal inertia has the potential to enhance our understanding of the climate, the geology, and the habitability of Mars. PMID:26213666
Martínez, G M; Rennó, N; Fischer, E; Borlina, C S; Hallet, B; de la Torre Juárez, M; Vasavada, A R; Ramos, M; Hamilton, V; Gomez-Elvira, J; Haberle, R M
2014-08-01
The analysis of the surface energy budget (SEB) yields insights into soil-atmosphere interactions and local climates, while the analysis of the thermal inertia (I) of shallow subsurfaces provides context for evaluating geological features. Mars orbital data have been used to determine thermal inertias at horizontal scales of ∼10(4) m(2) to ∼10(7) m(2). Here we use measurements of ground temperature and atmospheric variables by Curiosity to calculate thermal inertias at Gale Crater at horizontal scales of ∼10(2) m(2). We analyze three sols representing distinct environmental conditions and soil properties, sol 82 at Rocknest (RCK), sol 112 at Point Lake (PL), and sol 139 at Yellowknife Bay (YKB). Our results indicate that the largest thermal inertia I = 452 J m(-2) K(-1) s(-1/2) (SI units used throughout this article) is found at YKB followed by PL with I = 306 and RCK with I = 295. These values are consistent with the expected thermal inertias for the types of terrain imaged by Mastcam and with previous satellite estimations at Gale Crater. We also calculate the SEB using data from measurements by Curiosity's Rover Environmental Monitoring Station and dust opacity values derived from measurements by Mastcam. The knowledge of the SEB and thermal inertia has the potential to enhance our understanding of the climate, the geology, and the habitability of Mars.
Some Properties of Generalized Hypergeometric Thermal Coherent States
NASA Astrophysics Data System (ADS)
Popov, Dusan
2006-06-01
The generalized hypergeometric coherent states (GHCSs) have been introduced by Appl and Schiller [1] In the present paper we have extended some considerations about GHCSs to the mixed (thermal) states and applied, particularly, to the case of pseudoharmonic oscillator (PHO). The Husimi's Q distribution function and the diagonal P - distribution function, in the GHCSs representation, have been deduced for these mixed states. The obtained distribution functions were used to calculate thermal averages and to examine some nonclassical properties of the generalized hypergeometric thermal coherent states (GHTCSs), particularly for the PHO. We have also defined and calculated the thermal analogue of the Mandel parameter and the thermal analogue of the second-order correlation function. By particularizing the parameters p and q of the hypergeometric functions, we recover the usual Barut-Girardello coherent states and their main properties for the PHO from our previous paper [9] All calculations are performed in terms of the Meijer's G-functions [2], which are related to the hypergeometric functions. This manner provides an elegance and uniformity of the obtained results and so the GHCSs become a new field of application for these functions. Moreover, this mathematical approach can be used also for other kind of coherent states (e.g. Klauder-Perelomov, Gazeau-Klauder or nonlinear coherent states ([10] [12]).
Variable thermal properties and thermal relaxation time in hyperbolic heat conduction
NASA Technical Reports Server (NTRS)
Glass, David E.; Mcrae, D. Scott
1989-01-01
Numerical solutions were obtained for a finite slab with an applied surface heat flux at one boundary using both the hyperbolic (MacCormack's method) and parabolic (Crank-Nicolson method) heat conduction equations. The effects on the temperature distributions of varying density, specific heat, and thermal relaxation time were calculated. Each of these properties had an effect on the thermal front velocity (in the hyperbolic solution) as well as the temperatures in the medium. In the hyperbolic solutions, as the density or specific heat decreased with temperature, both the temperatures within the medium and the thermal front velocity increased. The value taken for the thermal relaxation time was found to determine the 'hyperbolicity' of the heat conduction model. The use of a time dependent relaxation time allowed for solutions where the thermal energy propagated as a high temperature wave initially, but approached a diffusion process more rapidly than was possible with a constant large relaxation time.
High-Fidelity Coupled Monte-Carlo/Thermal-Hydraulics Calculations
NASA Astrophysics Data System (ADS)
Ivanov, Aleksandar; Sanchez, Victor; Ivanov, Kostadin
2014-06-01
Monte Carlo methods have been used as reference reactor physics calculation tools worldwide. The advance in computer technology allows the calculation of detailed flux distributions in both space and energy. In most of the cases however, those calculations are done under the assumption of homogeneous material density and temperature distributions. The aim of this work is to develop a consistent methodology for providing realistic three-dimensional thermal-hydraulic distributions by coupling the in-house developed sub-channel code SUBCHANFLOW with the standard Monte-Carlo transport code MCNP. In addition to the innovative technique of on-the fly material definition, a flux-based weight-window technique has been introduced to improve both the magnitude and the distribution of the relative errors. Finally, a coupled code system for the simulation of steady-state reactor physics problems has been developed. Besides the problem of effective feedback data interchange between the codes, the treatment of temperature dependence of the continuous energy nuclear data has been investigated.
Thermal radiative properties: Nonmetallic solids.
NASA Technical Reports Server (NTRS)
Touloukian, Y. S.; Dewitt, D. P.
1972-01-01
The volume consists of a text on theory, estimation, and measurement, together with its bibliography, the main body of numerical data and its references, and the material index. The text material assumes a role complementary to the main body of numerical data. The physics and basic concepts of thermal radiation are discussed in detail, focusing attention on treatment of nonmetallic materials: theory, estimation, and methods of measurement. Numerical data is presented in a comprehensive manner. The scope of coverage includes the nonmetallic elements and their compounds, intermetallics, polymers, glasses, and minerals. Analyzed data graphs provide an evaluative review of the data. All data have been obtained from their original sources, and each data set is so referenced.
Thermal expansion properties of composite materials
NASA Technical Reports Server (NTRS)
Johnson, R. R.; Kural, M. H.; Mackey, G. B.
1981-01-01
Thermal expansion data for several composite materials, including generic epoxy resins, various graphite, boron, and glass fibers, and unidirectional and woven fabric composites in an epoxy matrix, were compiled. A discussion of the design, material, environmental, and fabrication properties affecting thermal expansion behavior is presented. Test methods and their accuracy are discussed. Analytical approaches to predict laminate coefficients of thermal expansion (CTE) based on lamination theory and micromechanics are also included. A discussion is included of methods of tuning a laminate to obtain a near-zero CTE for space applications.
Thermal properties for the thermal-hydraulics analyses of the BR2 maximum nominal heat flux.
Dionne, B.; Kim, Y. S.; Hofman, G. L.
2011-05-23
This memo describes the assumptions and references used in determining the thermal properties for the various materials used in the BR2 HEU (93% enriched in {sup 235}U) to LEU (19.75% enriched in {sup 235}U) conversion feasibility analysis. More specifically, this memo focuses on the materials contained within the pressure vessel (PV), i.e., the materials that are most relevant to the study of impact of the change of fuel from HEU to LEU. This section is regrouping all of the thermal property tables. Section 2 provides a summary of the thermal properties in form of tables while the following sections present the justification of these values. Section 3 presents a brief background on the approach used to evaluate the thermal properties of the dispersion fuel meat and specific heat capacity. Sections 4 to 7 discuss the material properties for the following materials: (i) aluminum, (ii) dispersion fuel meat (UAlx-Al and U-7Mo-Al), (iii) beryllium, and (iv) stainless steel. Section 8 discusses the impact of irradiation on material properties. Section 9 summarizes the material properties for typical operating temperatures. Appendix A elaborates on how to calculate dispersed phase's volume fraction. Appendix B shows the evolution of the BR2 maximum heat flux with burnup.
Thermal properties of three Fermi pulsars
NASA Astrophysics Data System (ADS)
Danilenko, A.; Karpova, A.; Kirichenko, A.; Shibanov, Y.; Shternin, P.; Zharikov, S.; Zyuzin, D.
2014-07-01
We analysed thermal properties of the Fermi pulsars J0357+3205, J1741-2054, and J0633+0632 using data from the XMM-Newton and Chandra archives. The X-ray spectra of all three pulsars can be fitted by sum of thermal and power-law components. For J1741-2054, the thermal component is best described by a blackbody model whose normalization suggests that the thermal emission comes from the bulk of the neutron star surface. The effective temperature of 60 eV, which is rather large for a pulsar as old as J1741-2054, makes it similar to the well-studied pulsar B1055-52, one of ``the three musketeers''. The thermal components of PSRs J0357+3205 and J0633+0632 can be equally well described by blackbody or the hydrogen atmosphere models. In the former case the normalizations suggest hot polar cap as thermal emission origin and only upper limits on the neutron stars surface temperatures can be computed. For the hydrogen atmosphere models, the normalizations are in agreement with emission coming from a substantial part of neutron star surface. Thermal properties of the pulsars are confronted with similar data on other isolated neutron stars and predictions of the neutron star cooling theory.
NASA Astrophysics Data System (ADS)
Khatun, Ayesha
The thermal properties of the sidewall lining materials are capturing attention since the last two decades. Good prediction of the dynamic thermal behaviour of Hall Heroult cells, including precise estimation of energy losses and location of the side ledge formed by the solidification of electrolytic bath, is made possible when the sidelining materials are well characterized in function of temperature. The present work aim at measuring the thermal diffusivity, heat capacity and thermal conductivity of silicon carbide (SiC), graphitic and graphitized carbon materials and cryolite (Na3AlF 6) based on transient characterization techniques. The thermal diffusivity and the heat capacity are measured by using state-of-the-art transient laser flash analyzer and differential scanning calorimeter respectively. The thermal conductivity is calculated by assuming a constant density. The range of precision error for each thermal property is also calculated for a finite number of data sets. Empirical correlation has been drawn for each of the properties to describe the relation with temperature in mathematical terms. Thermal characterization of the latent heat evolved during the melting of ledge is also carried out. Finally, based on the calculations conducted with a 2-D numerical model, the effect of the precision errors of temperature varying thermal properties of the sidewall materials and ledge on the dynamic behaviour of a laboratory scale phase change reactor is also presented. The results, so obtained, encourage further studies on the thermal properties of materials used in the aluminium reduction cell to find out the thermal environment inside the cell, heat loss estimation and effect of the additives on the location of ledge. Key words: Thermal conductivity, thermal diffusivity, heat capacity, temperature varying properties, precision error, phase change profile, latent heat.
Calculation and application of combined diffusion coefficients in thermal plasmas
NASA Astrophysics Data System (ADS)
Murphy, Anthony B.
2014-03-01
The combined diffusion coefficient method is widely used to treat the mixing and demixing of different plasma gases and vapours in thermal plasmas, such as welding arcs and plasma jets. It greatly simplifies the treatment of diffusion for many gas mixtures without sacrificing accuracy. Here, three subjects that are important in the implementation of the combined diffusion coefficient method are considered. First, it is shown that different expressions for the combined diffusion coefficients, arising from different definitions for the stoichiometric coefficients that assign the electrons to the two gases, are equivalent. Second, an approach is presented for calculating certain partial differential terms in the combined temperature and pressure diffusion coefficients that can cause difficulties. Finally, a method for applying the combined diffusion coefficients in computational models, which typically require diffusion to be expressed in terms of mass fraction gradients, is given.
Microscopic calculation of thermally induced spin-transfer torques
NASA Astrophysics Data System (ADS)
Kohno, Hiroshi; Hiraoka, Yuuki; Hatami, Moosa; Bauer, Gerrit E. W.
2016-09-01
Spin-transfer torques, both reactive and dissipative, induced by temperature gradients in conducting ferromagnets are calculated microscopically for smooth magnetization textures. Temperature gradients are treated à la Luttinger by introducing a fictitious gravitational field that couples to the energy density. The thermal torque coefficients obtained by the Kubo formula contain unphysical terms that diverge towards zero temperature. Such terms are caused by equilibrium components and should be subtracted before applying the Einstein-Luttinger relation. Only by following this procedure a familiar Mott-like formula is obtained for the dissipative spin-transfer torque. The result indicates that a fictitious field that couples to the entropy rather than energy would solve the issue from the outset.
Monte Carlo calculations of elementary particle properties
NASA Technical Reports Server (NTRS)
Guralnik, G. S.; Warnock, T.; Zemach, C.
1984-01-01
The object of this project is to calculate the masses of the elementary particles. This ambitious goal apparently is not possible using analytic methods or known approximation methods. However, it is probable that the power of a modern super computer will make at least part of the low lying mass spectrum accessible through direct numerical computation. Initial attempts by several groups at calculating this spectrum on small lattices of space time points have been very promising. Using new methods and super computers considerable progress has been made towards evaluating the mass spectrum on comparatively large lattices. Only more time and faster machines with increased storage will allow calculations of systems with guaranteed minimal boundary effects. The ideas that currently go into this calculation are outlined.
Effect of molecular models on viscosity and thermal conductivity calculations
NASA Astrophysics Data System (ADS)
Weaver, Andrew B.; Alexeenko, Alina A.
2014-12-01
The effect of molecular models on viscosity and thermal conductivity calculations is investigated. The Direct Simulation Monte Carlo (DSMC) method for rarefied gas flows is used to simulate Couette and Fourier flows as a means of obtaining the transport coefficients. Experimental measurements for argon (Ar) provide a baseline for comparison over a wide temperature range of 100-1,500 K. The variable hard sphere (VHS), variable soft sphere (VSS), and Lennard-Jones (L-J) molecular models have been implemented into a parallel version of Bird's one-dimensional DSMC code, DSMC1, and the model parameters have been recalibrated to the current experimental data set. While the VHS and VSS models only consider the short-range, repulsive forces, the L-J model also includes constributions from the long-range, dispersion forces. Theoretical results for viscosity and thermal conductivity indicate the L-J model is more accurate than the VSS model; with maximum errors of 1.4% and 3.0% in the range 300-1,500 K for L-J and VSS models, respectively. The range of validity of the VSS model is extended to 1,650 K through appropriate choices for the model parameters.
Modeling thermal properties of plutonium mononitride
NASA Astrophysics Data System (ADS)
Yu, H. L.; Huang, H.; Li, G.; Li, H. B.; Meng, D. Q.
2015-06-01
The thermal properties of plutonium mononitride (PuN) were investigated by molecular dynamics method. The interatomic potentials of PuN were fitted by using Chen-Möbius multiple lattice inversion technique. Based on these interatomic potentials, the lattice constant, bulk modulus, compressibility, cohesive energy and heat capacity of PuN were obtained and the results are well consistent with experimental data and previous reports. It indicates that the potentials we build in this study are effective for studying thermal properties of PuN.
Thermal and thermoelectric properties of graphene.
Xu, Yong; Li, Zuanyi; Duan, Wenhui
2014-06-12
The subject of thermal transport at the mesoscopic scale and in low-dimensional systems is interesting for both fundamental research and practical applications. As the first example of truly two-dimensional materials, graphene has exceptionally high thermal conductivity, and thus provides an ideal platform for the research. Here we review recent studies on thermal and thermoelectric properties of graphene, with an emphasis on experimental progresses. A general physical picture based on the Landauer transport formalism is introduced to understand underlying mechanisms. We show that the superior thermal conductivity of graphene is contributed not only by large ballistic thermal conductance but also by very long phonon mean free path (MFP). The long phonon MFP, explained by the low-dimensional nature and high sample purity of graphene, results in important isotope effects and size effects on thermal conduction. In terms of various scattering mechanisms in graphene, several approaches are suggested to control thermal conductivity. Among them, introducing rough boundaries and weakly-coupled interfaces are promising ways to suppress thermal conduction effectively. We also discuss the Seebeck effect of graphene. Graphene itself might not be a good thermoelectric material. However, the concepts developed by graphene research might be applied to improve thermoelectric performance of other materials.
Coefficients for calculating thermodynamic and transport properties of individual species
NASA Technical Reports Server (NTRS)
Mcbride, Bonnie J.; Gordon, Sanford; Reno, Martin A.
1993-01-01
Libraries of thermodynamic data and transport properties are given for individual species in the form of least-squares coefficients. Values of C(sup 0)(sub p)(T), H(sup 0)(T), and S(sup 0)(T) are available for 1130 solid, liquid, and gaseous species. Viscosity and thermal conductivity data are given for 155 gases. The original C(sup 0)(sub p)(T) values were fit to a fourth-order polynomial with integration constants for H(sup 0)(T) and S(sup 0)(T). For each species the integration constant for H(sup 0)(T) includes the heat of formation. Transport properties have a different functional form. The temperature range for most of the data is 300 to 5000 K, although some of the newer thermodynamic data have a range of 200 to 6000 K. Because the species are mainly possible products of reaction, the data are useful for chemical equilibrium and kinetics computer codes. Much of the data has been distributed for several years with the NASA Lewis equilibrium program CET89. The thermodynamic properties of the reference elements were updated along with about 175 species that involve the elements carbon, hydrogen, oxygen, and nitrogen. These sets of data will be distributed with the NASA Lewis personal computer program for calculating chemical equilibria, CETPC.
Thermal Properties for the Thermal-Hydraulics Analyses of the BR2 Maximum Nominal Heat Flux
Dionne, B.; Bergeron, A.; Licht, J. R.; Kim, Y. S.; Hofman, G. L.
2015-02-01
This memo describes the assumptions and references used in determining the thermal properties for the various materials used in the BR2 HEU (93% enriched in ^{235}U) to LEU (19.75% enriched in ^{235}U) conversion feasibility analysis. More specifically, this memo focuses on the materials contained within the pressure vessel (PV), i.e., the materials that are most relevant to the study of impact of the change of fuel from HEU to LEU. Section 2 provides a summary of the thermal properties in the form of tables while the following sections and appendices present the justification of these values. Section 3 presents a brief background on the approach used to evaluate the thermal properties of the dispersion fuel meat and specific heat capacity. Sections 4 to 7 discuss the material properties for the following materials: i) aluminum, ii) dispersion fuel meat (UAlx-Al and U-7Mo-Al), iii) beryllium, and iv) stainless steel. Section 8 discusses the impact of irradiation on material properties. Section 9 summarizes the material properties for typical operating temperatures. Appendix A elaborates on how to calculate dispersed phase’s volume fraction. Appendix B provides a revised methodology for determining the thermal conductivity as a function of burnup for HEU and LEU.
Optimization of Norbornadiene Compounds for Solar Thermal Storage by First-Principles Calculations.
Kuisma, Mikael; Lundin, Angelica; Moth-Poulsen, Kasper; Hyldgaard, Per; Erhart, Paul
2016-07-21
Molecular photoswitches capable of storing solar energy are interesting candidates for future renewable energy applications. Here, using quantum mechanical calculations, we carry out a systematic screening of crucial optical (solar spectrum match) and thermal (storage energy density) properties of 64 such compounds based on the norbornadiene-quadricyclane system. Whereas a substantial number of these molecules reach the theoretical maximum solar power conversion efficiency, this requires a strong red-shift of the absorption spectrum, which causes undesirable absorption by the photoisomer as well as reduced thermal stability. These compounds typically also have a large molecular mass, leading to low storage densities. By contrast, single-substituted systems achieve a good compromise between efficiency and storage density, while avoiding competing absorption by the photo-isomer. This establishes guiding principles for the future development of molecular solar thermal storage systems.
Calculated fission properties of the heaviest elements
Moeller, P.; Nix, J.R.; Swiatecki, W.J.
1986-09-01
A quantitative calculation is presented that shows where high-kinetic-energy symmetric fission occurs and why it is associated with a sudden and large decrease in fission half-lives. The study is based on calculations of potential-energy surfaces in the macroscopic-microscopic model and a semi-empirical model for the nuclear inertia. For the macroscopic part a Yukawa-plus-exponential model is used and for the microscopic part a folded-Yukawa single-particle potential is used. The three-quadratic-surface parameterization generates shapes for which the potential-energy surfaces are calculated. The use of this parameterization and the use of the finite-range macroscopic model allows for the study of two touching spheres and similar shapes. The results of the calculations in terms of potential-energy surfaces and fission half-lives are presented for heavy even nuclei. The surfaces are displayed in the form of contour diagrams as functions of two moments of the shape. 53 refs., 15 figs., 1 tab.
Novel thermal properties of nanostructured materials.
Eastman, J. A.
1999-01-13
A new class of heat transfer fluids, termed nanofluids, has been developed by suspending nanocrystalline particles in liquids. Due to the orders-of-magnitude larger thermal conductivities of solids compared to those of liquids such as water, significantly enhanced thermal properties are obtained with nanofluids. For example, an approximately 20% improvement in effective thermal conductivity is observed when 5 vol.% CuO nanoparticles are added to water. Even more importantly, the heat transfer coefficient of water under dynamic flow conditions is increased more than 15% with the addition of less than 1 vol.% CuO particles. The use of nanofluids could impact many industrial sectors, including transportation, energy supply and production, electronics, textiles, and paper production by, for example, decreasing pumping power needs or reducing heat exchanger sizes. In contrast to the enhancement in effective thermal transport rates that is obtained when nanoparticles are suspended in fluids, nanocrystalline coatings are expected to exhibit reduced thermal conductivities compared to coarse-grained coatings. Reduced thermal conductivities are predicted to arise because of a reduction in the mean free path of phonons due to presence of grain boundaries. This behavior, combined with improved mechanical properties, makes nanostructured zirconia coatings excellent candidates for future applications as thermal barriers. Yttria-stabilized zirconia (YSZ) thin films are being produced by metal-organic chemical vapor deposition techniques. Preliminary results have indicated that the thermal conductivity is reduced by approximately a factor-of-two at room temperature in 10 nm grain-sized YSZ compared to coarse-grained or single crystal YSZ.
Heuze, F.E.
1983-03-01
An attempt to model the complex thermal and mechanical phenomena occurring in the disposal of high-level nuclear wastes in rock at high power loading is described. Such processes include melting of the rock, convection of the molten material, and very high stressing of the rock mass, leading to new fracturing. Because of the phase changes and the wide temperature ranges considered, realistic models must provide for coupling of the thermal and mechanical calculations, for large deformations, and for steady-state temperature-depenent creep of the rock mass. Explicit representation of convection would be desirable, as would the ability to show fracture development and migration of fluids in cracks. Enhancements to SNAGRE consisted of: array modifications to accommodate complex variations of thermal and mechanical properties with temperature; introduction of the ability of calculate thermally induced stresses; improved management of the minimum time step and minimum temperature step to increase code efficiency; introduction of a variable heat-generation algorithm to accommodate heat decay of the nuclear materials; streamlining of the code by general editing and extensive deletion of coding used in mesh generation; and updating of the program users' manual. The enhanced LLNL version of the code was renamed LSANGRE. Phase changes were handled by introducing sharp variations in the specific heat of the rock in a narrow range about the melting point. The accuracy of this procedure was tested successfully on a melting slab problem. LSANGRE replicated the results of both the analytical solution and calculations with the finite difference TRUMP code. Following enhancement and verification, a purely thermal calculation was carried to 105 years. It went beyond the extent of maximum melt and into the beginning of the cooling phase.
Thermal properties of food and pharmaceutical powders
NASA Astrophysics Data System (ADS)
Abiad, Mohamad Ghassan
Foods and pharmaceuticals are complex systems usually exposed to various environmental conditions during processing and thus storage, stability, functionality and quality are key attributes that deserve careful attention. The quality and stability of foods and pharmaceuticals are mainly affected by environmental conditions such as temperature, humidity, time, and processing conditions (e.g. shear, pressure) under which they may undergo physical and/or chemical transformations. Glass transition as well as other thermal properties is a key to understand how external conditions affect physical changes of such materials. Development of new materials and understanding the physico-chemical behavior of existing ones require a scientific foundation that translates into safe and high quality foods, improved quality of pharmaceuticals and nutraceuticals with lower risk to patients and functional efficacy of polymers used in food and medicinal products. This research provides an overview of the glass transition and other thermal properties and introduces novel methods developed to characterize such properties.
Thermal conductivity of wurtzite and zinc blende cubic phases of BeO from ab initio calculations
NASA Astrophysics Data System (ADS)
Malakkal, Linu; Szpunar, Barbara; Siripurapu, Ravi Kiran; Zuniga, Juan Carlos; Szpunar, Jerzy A.
2017-03-01
The structural, mechanical, thermal and thermodynamic properties of Beryllium oxide (BeO) in the zinc blende (ZB) and wurtzite (WZ) form have been calculated using the density functional theory (DFT) in the general gradient approximation (GGA). The ground state structural and elastic properties of wurtzite BeO (w-BeO) is calculated using the new GGA ultrasoft pseudopotentials for solids (pbesol); the simulated results have shown excellent agreement with the experiments. The thermodynamic properties are studied using quasi-harmonic approximation (QHA), and the predicted properties agree well for the WZ phase for which the experimental data are available, while for ZB phase it remains to be validated with future experiments. Both Boltzmann transport equation (BTE) and Slack model were used to calculate the lattice thermal conductivity of wurtzite BeO (w-BeO). Furthermore, the thermal conductivity along the crystallographic 'a' and 'c' axis of wurtzite BeO is investigated using BTE. Our calculation of w-BeO agrees well with the available experimental measurements. Apart from these studies on w-BeO, we have also compared the mechanical, structural and phonon dispersions of z-BeO with previously reported theoretical studies. Additionally we report the volume thermal expansion and the heat capacity at constant pressure of z-BeO for the first time and the bulk thermal conductivity of zinc blende BeO (z-BeO) using BTE.
Heat Transfer Principles in Thermal Calculation of Structures in Fire.
Zhang, Chao; Usmani, Asif
2015-11-01
Structural fire engineering (SFE) is a relatively new interdisciplinary subject, which requires a comprehensive knowledge of heat transfer, fire dynamics and structural analysis. It is predominantly the community of structural engineers who currently carry out most of the structural fire engineering research and design work. The structural engineering curriculum in universities and colleges do not usually include courses in heat transfer and fire dynamics. In some institutions of higher education, there are graduate courses for fire resistant design which focus on the design approaches in codes. As a result, structural engineers who are responsible for structural fire safety and are competent to do their jobs by following the rules specified in prescriptive codes may find it difficult to move toward performance-based fire safety design which requires a deep understanding of both fire and heat. Fire safety engineers, on the other hand, are usually focused on fire development and smoke control, and may not be familiar with the heat transfer principles used in structural fire analysis, or structural failure analysis. This paper discusses the fundamental heat transfer principles in thermal calculation of structures in fire, which might serve as an educational guide for students, engineers and researchers. Insights on problems which are commonly ignored in performance based fire safety design are also presented.
Tables for simplifying calculations of activities produced by thermal neutrons
Senftle, F.E.; Champion, W.R.
1954-01-01
The method of calculation described is useful for the types of work of which examples are given. It is also useful in making rapid comparison of the activities that might be expected from several different elements. For instance, suppose it is desired to know which of the three elements, cobalt, nickel, or vanadium is, under similar conditions, activated to the greatest extent by thermal neutrons. If reference is made to a cross-section table only, the values may be misleading unless properly interpreted by a suitable comparison of half-lives and abundances. In this table all the variables have been combined and the desired information can be obtained directly from the values of A 3??, the activity produced per gram per second of irradiation, under the stated conditions. Hence, it is easily seen that, under similar circumstances of irradiation, vanadium is most easily activated even though the cross section of one of the cobalt isotopes is nearly five times that of vanadium and the cross section of one of the nickel isotopes is three times that of vanadium. ?? 1954 Societa?? Italiana di Fisica.
Heat Transfer Principles in Thermal Calculation of Structures in Fire
Zhang, Chao; Usmani, Asif
2016-01-01
Structural fire engineering (SFE) is a relatively new interdisciplinary subject, which requires a comprehensive knowledge of heat transfer, fire dynamics and structural analysis. It is predominantly the community of structural engineers who currently carry out most of the structural fire engineering research and design work. The structural engineering curriculum in universities and colleges do not usually include courses in heat transfer and fire dynamics. In some institutions of higher education, there are graduate courses for fire resistant design which focus on the design approaches in codes. As a result, structural engineers who are responsible for structural fire safety and are competent to do their jobs by following the rules specified in prescriptive codes may find it difficult to move toward performance-based fire safety design which requires a deep understanding of both fire and heat. Fire safety engineers, on the other hand, are usually focused on fire development and smoke control, and may not be familiar with the heat transfer principles used in structural fire analysis, or structural failure analysis. This paper discusses the fundamental heat transfer principles in thermal calculation of structures in fire, which might serve as an educational guide for students, engineers and researchers. Insights on problems which are commonly ignored in performance based fire safety design are also presented. PMID:26783379
Post-test thermal calculations and data analyses for the Spent Fuel Test, Climax
Montan, D.N.; Patrick, W.C.
1986-06-01
After the Spent Fuel Test - Climax (SFT-C) was completed, additional calculations were performed using the best available (directly measured or inferred from measurements made during the test) input parameters, thermal properties, and power levels. This report documents those calculations and compares the results with measurements made during the three-year heating phase and six-month posttest cooling phase of the SFT-C. Three basic types of heat-transfer calculations include a combined two-dimensional/three-dimensional, infinite-length, finite-difference model; a fully three-dimensional, finite-length, finite-difference model; and a fully three-dimensional, finite-length, analytical solution. The finite-length model much more accurately reflects heat flow near the ends of the array and produces cooler temperatures everywhere than does its infinite-length counterpart. 14 refs., 144 figs., 4 tabs.
WASP: A flexible FORTRAN 4 computer code for calculating water and steam properties
NASA Technical Reports Server (NTRS)
Hendricks, R. C.; Peller, I. C.; Baron, A. K.
1973-01-01
A FORTRAN 4 subprogram, WASP, was developed to calculate the thermodynamic and transport properties of water and steam. The temperature range is from the triple point to 1750 K, and the pressure range is from 0.1 to 100 MN/m2 (1 to 1000 bars) for the thermodynamic properties and to 50 MN/m2 (500 bars) for thermal conductivity and to 80 MN/m2 (800 bars) for viscosity. WASP accepts any two of pressure, temperature, and density as input conditions. In addition, pressure and either entropy or enthalpy are also allowable input variables. This flexibility is especially useful in cycle analysis. The properties available in any combination as output include temperature, density, pressure, entropy, enthalpy, specific heats, sonic velocity, viscosity, thermal conductivity, surface tension, and the Laplace constant. The subroutine structure is modular so that the user can choose only those subroutines necessary to his calculations. Metastable calculations can also be made by using WASP.
First-principles calculations on thermodynamic properties of BaTiO3 rhombohedral phase.
Bandura, Andrei V; Evarestov, Robert A
2012-07-05
The calculations based on the linear combination of atomic orbitals have been performed for the low-temperature phase of BaTiO(3) crystal. Structural and electronic properties, as well as phonon frequencies were obtained using hybrid PBE0 exchange-correlation functional. The calculated frequencies and total energies at different volumes have been used to determine the equation of state and thermal contribution to the Helmholtz free energy within the quasiharmonic approximation. For the first time, the bulk modulus, volume thermal expansion coefficient, heat capacity, and Grüneisen parameters in BaTiO(3) rhombohedral phase have been estimated at zero pressure and temperatures form 0 to 200 K, based on the results of first-principles calculations. Empirical equation has been proposed to reproduce the temperature dependence of the calculated quantities. The agreement between the theoretical and experimental thermodynamic properties was found to be satisfactory.
Thermal properties of methane gas hydrates
Waite, William F.
2007-01-01
Gas hydrates are crystalline solids in which molecules of a “guest” species occupy and stabilize cages formed by water molecules. Similar to ice in appearance (fig. 1), gas hydrates are stable at high pressures and temperatures above freezing (0°C). Methane is the most common naturally occurring hydrate guest species. Methane hydrates, also called simply “gas hydrates,” are extremely concentrated stores of methane and are found in shallow permafrost and continental margin sediments worldwide. Brought to sea-level conditions, methane hydrate breaks down and releases up to 160 times its own volume in methane gas. The methane stored in gas hydrates is of interest and concern to policy makers as a potential alternative energy resource and as a potent greenhouse gas that could be released from sediments to the atmosphere and ocean during global warming. In continental margin settings, methane release from gas hydrates also is a potential geohazard and could cause submarine landslides that endanger offshore infrastructure. Gas hydrate stability is sensitive to temperature changes. To understand methane release from gas hydrate, the U.S. Geological Survey (USGS) conducted a laboratory investigation of pure methane hydrate thermal properties at conditions relevant to accumulations of naturally occurring methane hydrate. Prior to this work, thermal properties for gas hydrates generally were measured on analog systems such as ice and non-methane hydrates or at temperatures below freezing; these conditions limit direct comparisons to methane hydrates in marine and permafrost sediment. Three thermal properties, defined succinctly by Briaud and Chaouch (1997), are estimated from the experiments described here: - Thermal conductivity, λ: if λ is high, heat travels easily through the material. - Thermal diffusivity, κ: if κ is high, it takes little time for the temperature to rise in the material. - Specific heat, cp: if cp is high, it takes a great deal of heat to
Acoustic and thermal properties of tissue
NASA Astrophysics Data System (ADS)
Retat, L.; Rivens, I.; ter Haar, G. R.
2012-10-01
Differences in ultrasound (US) and thermal properties of abdominal soft tissues may affect the delivery of thermal therapies such as high intensity focused ultrasound and may provide a basis for US monitoring of such therapies. 21 rat livers were obtained, within one hour of surgical removal. For a single liver, 3 lobes were selected and each treated in one of 3 ways: maintained at room temperature, water bath heated to 50°C ± 1°C for 10 ± 0.5 minutes, or water bath heated to 60°C ± 1°C for 10 ± 0.6 minutes. The attenuation coefficient, speed of sound and thermal conductivity of fresh rat liver was measured. The attenuation coefficients and speed of sound were measured using the finite-amplitude insertion-substitution (FAIS) method. For each rat liver, the control and treated lobes were scanned using a pair of weakly focused 2.5 MHz Imasonic transducers over the range 1.8 to 3 MHz. The conductivity measurement apparatus was designed to provide one-dimensional heat flow through each specimen using a combination of insulation, heat source and heat sink. Using 35 MHz US images to determine the volume of air trapped in the system, the thermal conductivity was corrected using a simulation based on the Helmhotz bio-heat equation. The process of correlating these results with biological properties is discussed.
Thermal properties of an erythritol derivative
NASA Astrophysics Data System (ADS)
Trhlikova, Lucie; Prikryl, Radek; Zmeskal, Oldrich
2016-06-01
Erythritol (C4H10O4) is a sugar alcohol (or polyol) that is commonly used in the food industry. Its molar mass is 122.12 g.mol-1 and mass density 1450 kg.m-3. Erythritol, an odorless crystalline powder, can also be characterized by other physical parameters like melting temperature (121 °C) and boiling temperature (329 °C). The substance can be used for the accumulation of energy in heat exchangers based on various oils or water. The PlusICE A118 product manufactured by the PCM Products Ltd. company (melting temperature Θ = 118 °C, specific heat capacity cp = 2.70 kJ.K-1.kg-1, mass density 1450 kg.m-3, latent heat capacity 340 kJ.kg-1, volumetric heat capacity 493 MJ.m-3) is based on an erythritol-type medium. Thermal properties of the PlusICE A118 product in both solid and liquid phase were investigated for this purpose in terms of potential applications. Temperature dependences of its thermal parameters (thermal diffusivity, thermal conductivity, and specific heat) were determined using a transient (step-wise) method. A fractal model of heat transport was used for determination of the above thermal parameters. This model is independent of geometry and type of sample heating. Moreover, it also considers heat losses. The experiment confirmed the formerly declared value of phase change temperature, about 120 °C.
Computation of Thermally Perfect Compressible Flow Properties
NASA Technical Reports Server (NTRS)
Witte, David W.; Tatum, Kenneth E.; Williams, S. Blake
1996-01-01
A set of compressible flow relations for a thermally perfect, calorically imperfect gas are derived for a value of c(sub p) (specific heat at constant pressure) expressed as a polynomial function of temperature and developed into a computer program, referred to as the Thermally Perfect Gas (TPG) code. The code is available free from the NASA Langley Software Server at URL http://www.larc.nasa.gov/LSS. The code produces tables of compressible flow properties similar to those found in NACA Report 1135. Unlike the NACA Report 1135 tables which are valid only in the calorically perfect temperature regime the TPG code results are also valid in the thermally perfect, calorically imperfect temperature regime, giving the TPG code a considerably larger range of temperature application. Accuracy of the TPG code in the calorically perfect and in the thermally perfect, calorically imperfect temperature regimes are verified by comparisons with the methods of NACA Report 1135. The advantages of the TPG code compared to the thermally perfect, calorically imperfect method of NACA Report 1135 are its applicability to any type of gas (monatomic, diatomic, triatomic, or polyatomic) or any specified mixture of gases, ease-of-use, and tabulated results.
Tabulated In-Drift Geometric and Thermal Properties Used In Drift-Scale Models for TSPA-SR
N.D. Francis
2000-06-16
The objective of this calculation is to provide in-drift physical properties required by the drift-scale models (both two- and three-dimensional) used in total system performance assessments (TSPA). The physical properties include waste package geometry, waste package thermal properties, emplacement drift geometry including backfill and invert geometry and properties (both thermal and hydrologic), drip shield geometry and thermal properties, all tabulated in a single source.
Crystal dynamics and thermal properties of neptunium dioxide
NASA Astrophysics Data System (ADS)
Maldonado, P.; Paolasini, L.; Oppeneer, P. M.; Forrest, T. R.; Prodi, A.; Magnani, N.; Bosak, A.; Lander, G. H.; Caciuffo, R.
2016-04-01
We report an experimental and theoretical investigation of the lattice dynamics and thermal properties of the actinide dioxide NpO2. The energy-wave-vector dispersion relation for normal modes of vibration propagating along the [001 ] , [110 ] , and [111 ] high-symmetry lines in NpO2 at room temperature has been determined by measuring the coherent one-phonon scattering of x rays from an ˜1.2 -mg single-crystal specimen, the largest available single crystal for this compound. The results are compared against ab initio phonon dispersions computed within the first-principles density functional theory in the generalized gradient approximation plus Hubbard U correlation (GGA+U ) approach, taking into account third-order anharmonicity effects in the quasiharmonic approximation. Good agreement with the experiment is obtained for calculations with an on-site Coulomb parameter U =4 eV and Hund's exchange J =0.6 eV in line with previous electronic structure calculations. We further compute the thermal expansion, heat capacity, thermal conductivity, phonon linewidth, and thermal phonon softening, and compare with available experiments. The theoretical and measured heat capacities are in close agreement with another. About 27% of the calculated thermal conductivity is due to phonons with energy higher than 25 meV (˜6 THz ), suggesting an important role of high-energy optical phonons in the heat transport. The simulated thermal expansion reproduces well the experimental data up to about 1000 K, indicating a failure of the quasiharmonic approximation above this limit.
Determining the Thermal Properties of Space Lubricants
NASA Technical Reports Server (NTRS)
Maldonado, Christina M.
2004-01-01
Many mechanisms used in spacecrafts, such as satellites or the space shuttle, employ ball bearings or gears that need to be lubricated. Normally this is not a problem, but in outer space the regular lubricants that are used on Earth will not function properly. Regular lubricants will quickly vaporize in the near vacuum of space. A unique liquid called a perfluoropolyalkylether (PFPE) has an extremely low vapor pressure, around l0(exp -10) torr at 20 C, and has been used in numerous satellites and is currently used in the space shuttle. Many people refer to the PFPEs as "liquid Teflon". PFPE lubricants however, have a number of problems with them. Lubricants need many soluble additives, especially boundary and anti-wear additives, in them to function properly. All the regular known boundary additives are insoluble in PFPEs and so PFPEs lubricate poorly under highly loaded conditions leading to many malfunctioning ball bearings and gears. JAXA, the Japanese Space Agency, is designing and building a centrifuge rotor to be installed in the International Space Station. The centrifuge rotor is part of a biology lab module. They have selected a PFPE lubricant to lubricate the rotor s ball bearings and NASA bearing experts feel this is not a wise choice. An assessment of the centrifuge rotor design is being conducted by NASA and part of the assessment entails knowing the physical and thermal properties of the PFPE lubricant. One important property, the thermal diffusivity, is not known. An experimental apparatus was set up in order to measure the thermal diffusivity of the PFPE. The apparatus consists of a constant temperature heat source, cylindrical Pyrex glassware, a thermal couple and digital thermometer. The apparatus was tested and calibrated using water since the thermal diffusivity of water is known.
Experimental methods of determining thermal properties of granite
Technology Transfer Automated Retrieval System (TEKTRAN)
Determination of thermal properties of granite using the block method is discussed and compared with other methods. Problems that limit the accuracy of contact method in determining thermal properties of porous media are evaluated. Thermal properties of granite is determined in the laboratory with a...
Computation of Thermally Perfect Oblique Shock Wave Properties
NASA Technical Reports Server (NTRS)
Tatum, Kenneth E.
1997-01-01
A set of compressible flow relations describing flow properties across oblique shock waves, derived for a thermally perfect, calorically imperfect gas, is applied within the existing thermally perfect gas (TPG) computer code. The relations are based upon the specific heat expressed as a polynomial function of temperature. The updated code produces tables of compressible flow properties of oblique shock waves, as well as the original properties of normal shock waves and basic isentropic flow, in a format similar to the tables for normal shock waves found in NACA Rep. 1135. The code results are validated in both the calorically perfect and the calorically imperfect, thermally perfect temperature regimes through comparisons with the theoretical methods of NACA Rep. 1135. The advantages of the TPG code for oblique shock wave calculations, as well as for the properties of isentropic flow and normal shock waves, are its ease of use and its applicability to any type of gas (monatomic, diatomic, triatomic, polyatomic, or any specified mixture thereof).
Computation of Thermally Perfect Properties of Oblique Shock Waves
NASA Technical Reports Server (NTRS)
Tatum, Kenneth E.
1996-01-01
A set of compressible flow relations describing flow properties across oblique shock waves, derived for a thermally perfect, calorically imperfect gas, is applied within the existing thermally perfect gas (TPG) computer code. The relations are based upon a value of cp expressed as a polynomial function of temperature. The updated code produces tables of compressible flow properties of oblique shock waves, as well as the original properties of normal shock waves and basic isentropic flow, in a format similar to the tables for normal shock waves found in NACA Rep. 1135. The code results are validated in both the calorically perfect and the calorically imperfect, thermally perfect temperature regimes through comparisons with the theoretical methods of NACA Rep. 1135, and with a state-of-the-art computational fluid dynamics code. The advantages of the TPG code for oblique shock wave calculations, as well as for the properties of isentropic flow and normal shock waves, are its ease of use, and its applicability to any type of gas (monatomic, diatomic, triatomic, polyatomic, or any specified mixture thereof).
Biodegradable compounds: Rheological, mechanical and thermal properties
NASA Astrophysics Data System (ADS)
Nobile, Maria Rossella; Lucia, G.; Santella, M.; Malinconico, M.; Cerruti, P.; Pantani, R.
2015-12-01
Recently great attention from industry has been focused on biodegradable polyesters derived from renewable resources. In particular, PLA has attracted great interest due to its high strength and high modulus and a good biocompatibility, however its brittleness and low heat distortion temperature (HDT) restrict its wide application. On the other hand, Poly(butylene succinate) (PBS) is a biodegradable polymer with a low tensile modulus but characterized by a high flexibility, excellent impact strength, good thermal and chemical resistance. In this work the two aliphatic biodegradable polyesters PBS and PLA were selected with the aim to obtain a biodegradable material for the industry of plastic cups and plates. PBS was also blended with a thermoplastic starch. Talc was also added to the compounds because of its low cost and its effectiveness in increasing the modulus and the HDT of polymers. The compounds were obtained by melt compounding in a single screw extruder and the rheological, mechanical and thermal properties were investigated. The properties of the two compounds were compared and it was found that the values of the tensile modulus and elongation at break measured for the PBS/PLA/Talc compound make it interesting for the production of disposable plates and cups. In terms of thermal resistance the compounds have HDTs high enough to contain hot food or beverages. The PLA/PBS/Talc compound can be, then, considered as biodegradable substitute for polystyrene for the production of disposable plates and cups for hot food and beverages.
NASA Astrophysics Data System (ADS)
Wang, Hsin; Porter, Wallace D.; Böttner, Harald; König, Jan; Chen, Lidong; Bai, Shengqiang; Tritt, Terry M.; Mayolet, Alex; Senawiratne, Jayantha; Smith, Charlene; Harris, Fred; Gilbert, Patricia; Sharp, Jeff; Lo, Jason; Kleinke, Holger; Kiss, Laszlo
2013-06-01
For bulk thermoelectrics, improvement of the figure of merit ZT to above 2 from the current values of 1.0 to 1.5 would enhance their competitiveness with alternative technologies. In recent years, the most significant improvements in ZT have mainly been due to successful reduction of thermal conductivity. However, thermal conductivity is difficult to measure directly at high temperatures. Combined measurements of thermal diffusivity, specific heat, and mass density are a widely used alternative to direct measurement of thermal conductivity. In this work, thermal conductivity is shown to be the factor in the calculation of ZT with the greatest measurement uncertainty. The International Energy Agency (IEA) group, under the implementing agreement for Advanced Materials for Transportation (AMT), has conducted two international round-robins since 2009. This paper, part II of our report on the international round-robin testing of transport properties of bulk bismuth telluride, focuses on thermal diffusivity, specific heat, and thermal conductivity measurements.
Nanofluid enhancement of mineral oil and thermal properties instrument design
NASA Astrophysics Data System (ADS)
Wilborn, Eli
thermal conductivities of various fluids. The second design calculated a thermal conductivity of water to be 0.59W/m2 c', while the commonly accepted value is 0.58W/ m2c', which is well within a tolerable range of error to accept this value as accurate at the experimental conditions. This heat transfer cell also calculated the thermal conductivity value for AMSOIL synthetic motor oil to be 0.12W/m2 c and 0.10W/m2c for mineral oil, both of these values are within the expected ranges of thermal conductivity for oils. The second goal of applying the heat transfer enhancement properties of a nanofluid to a transformer cooling application proved to be futile for Copper Oxide(40nm) and Carbon coated Copper nanoparticles(25nm) in mineral oil. All of the attempted nanofluids fell out of suspension within a timeframe of a day, and in a transformer cell where natural convection is the only means of flow available that contributes to keeping the nanoparticles suspended, there is not enough flow to keep the nanoparticles from falling out of suspension. That is why unless the transformer industry moves towards another coolant besides mineral oil, heat transfer enhancement using Copper Oxide (40nm) or Carbon Coated nanoparticles (25nm) in a mineral oil nanofluid is not a viable option.
40 CFR 80.66 - Calculation of reformulated gasoline properties.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 17 2013-07-01 2013-07-01 false Calculation of reformulated gasoline... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Reformulated Gasoline § 80.66 Calculation of reformulated gasoline properties. (a) All volume measurements required by these regulations shall...
40 CFR 80.66 - Calculation of reformulated gasoline properties.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 17 2014-07-01 2014-07-01 false Calculation of reformulated gasoline... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Reformulated Gasoline § 80.66 Calculation of reformulated gasoline properties. (a) All volume measurements required by these regulations shall...
Alon, Leeor; Sodickson, Daniel K; Deniz, Cem M
2016-10-01
Deposition of radiofrequency (RF) energy can be quantified via electric field or temperature change measurements. Magnetic resonance imaging has been used as a tool to measure three dimensional small temperature changes associated with RF radiation exposure. When duration of RF exposure is long, conversion from temperature change to specific absorption rate (SAR) is nontrivial due to prominent heat-diffusion and conduction effects. In this work, we demonstrated a method for calculation of SAR via an inversion of the heat equation including heat-diffusion and conduction effects. This method utilizes high-resolution three dimensional magnetic resonance temperature images and measured thermal properties of the phantom to achieve accurate calculation of SAR. Accuracy of the proposed method was analyzed with respect to operating frequency of a dipole antenna and parameters used in heat equation inversion. Bioelectromagnetics. 37:493-503, 2016. © 2016 Wiley Periodicals, Inc.
Meng-Lund, Helena; Friis, Natascha; van de Weert, Marco; Rantanen, Jukka; Poso, Antti; Grohganz, Holger; Jorgensen, Lene
2017-03-21
A quantitative structure-property relationship (QSPR) between protein stability and the physicochemical properties of excipients was investigated to enable a more rational choice of stabilizing excipients than prior knowledge. The thermal transition temperature and aggregation time were determined for lysozyme in combination with 13 different amino acids using high throughput fluorescence spectroscopy and kinetic static light scattering measurements. On the theoretical side, around 200 2D and 3D molecular descriptors were calculated based on the amino acids' chemical structure. Multivariate data analysis was applied to correlate the descriptors with the experimental results. It was possible to identify descriptors, i.e. amino acids properties, with a positive influence on either transition temperature or aggregation onset time, or both. A high number of hydrogen bond acceptor moieties was the most prominent stabilizing factor for both responses, whereas hydrophilic surface properties and high molecular mass density mostly had a positive influence on the unfolding temperature. A high partition coefficient (logP(o/w)) was identified as the most prominent destabilizing factor for both responses. The QSPR shows good correlation between calculated molecular descriptors and the measured stabilizing effect of amino acids on lysozyme.
Calculating nonlocal optical properties of structures with arbitrary shape.
McMahon, J. M.; Gray, S. K.; Schatz, G. C.; Northwestern Univ.
2010-07-16
In a recent Letter [J. M. McMahon, S. K. Gray, and G. C. Schatz, Phys. Rev. Lett. 103, 097403 (2009)], we outlined a computational method to calculate the optical properties of structures with a spatially nonlocal dielectric function. In this paper, we detail the full method and verify it against analytical results for cylindrical nanowires. Then, as examples of our method, we calculate the optical properties of Au nanostructures in one, two, and three dimensions. We first calculate the transmission, reflection, and absorption spectra of thin films. Because of their simplicity, these systems demonstrate clearly the longitudinal (or volume) plasmons characteristic of nonlocal effects, which result in anomalous absorption and plasmon blueshifting. We then study the optical properties of spherical nanoparticles, which also exhibit such nonlocal effects. Finally, we compare the maximum and average electric field enhancements around nanowires of various shapes to local theory predictions. We demonstrate that when nonlocal effects are included, significant decreases in such properties can occur.
1972-01-01
Touloukian , Series Editor C. Y. Ho, Series Teohnloal Editor Volume 1. Thermal Conductivity-Metallic Elements and Alloys Volume 2. Thermal...Elements and Alloys Volume 8. Thermal Radiative Properties -Nonmetallic Solids Volume 9. Thermal Radiative Properties -Coatings Volume 10. Thermal...Thermophysicul Properties Reseanh Literulure Retriexul (JutJe. 3 Vols.. Plenum Press. 1967. 116. Touloukian . Y. S. and DeWitt. D. P.. Thermal
Ab initio study of the thermodynamic properties and the phonon calculations of Zircon and Reidite
NASA Astrophysics Data System (ADS)
Chaudhari, Mrunalkumar; Du, Jincheng
2011-03-01
Zircon and Reidite are the polymorphs of Zirconium Silicate which find its importance geologically, because of its natural hosting to various radioactive elements in the crust of the earth. High permittivity also makes it a promising material for the gate dielectric material in metal-oxide semiconductors. Knowledge of the thermodynamic properties and the phonon based calculations is very critical to understand the high temperature and high pressure properties in order to consider its application as an effective natural storage for the radioactive wastes. These properties are thoroughly studied both computationally and experimentally for zircon, while significantly less attention was paid to reidite in the literature. The thermodynamic properties and phonon calculations of Zircon and Reidite were studied using ab initio based periodic density-functional theory (DFT) based calculations using the generalized gradient approximation (GGA). Various properties such as free energy, internal energy, entropy, heat capacity and thermal displacement as a function of temperature is calculated using the PHONON software. Various phonon based density of states and dispersion curves are calculated and compared with the experimental data. No first principles based computational results were reported up to now. Calculated bulk properties agree very well with the experimental data in the literature.
Verification Of Energy Balance In The Ansys V5.4 Thermal Calculations
H. Marr; M.J. Anderson
2001-02-08
The objective of this calculation is to verify the energy balance of the thermal calculations analyzed by ANSYS Version (V) 5.4 solver (see Section 4). The scope of this calculation is limited to calculating the energy balance of a two-dimensional repository thermal representation using the temperatures obtained from ANSYS V5.4. The procedure, AP-3.124, Calculations (Ref. 3), and the Technical Work Plan for: Waste Package Design Description for LA (Ref. 2) are used to develop this calculation. The associated activity is the development of engineering evaluations to support the Licensing Application design activities.
Measurement of Thermal Radiation Properties of Solids
NASA Technical Reports Server (NTRS)
Richmond, J. C. (Editor)
1963-01-01
The overall objectives of the Symposium were to afford (1) an opportunity for workers in the field to describe the equipment and procedures currently in use for measuring thermal radiation properties of solids, (2) an opportunity for constructive criticism of the material presented, and (3) an open forum for discussion of mutual problems. It was also the hope of the sponsors that the published proceedings of the Symposium would serve as a valuable reference on measurement techniques for evaluating thermal radiation properties of solids, partic.ularly for those with limited experience in the field. Because of the strong dependence of emitted flux upon temperature, the program committee thought it advisable to devote the first session to a discussion of the problems of temperature measurement. All of the papers in Session I were presented at the request of and upon topics suggested by the Committee. Because of time and space limitations, it, was impossible to consider all temperature measurement problems that might arise--the objective was rather to call to the attention of the reader some of the problems that might be encountered, and to provide references that might provide solutions.
Thermal and rheological properties of breadfruit starch.
Wang, Xueyu; Chen, Ling; Li, Xiaoxi; Xie, Fengwei; Liu, Hongshen; Yu, Long
2011-01-01
The thermal and rheological properties of breadfruit starch were studied using DSC and 2 different rheometers. It was found that the gelatinization temperature of starch with excess moisture content (>70%) was at approximately 75 °C. A new endotherm was detected at about 173 °C when the moisture content was lower than required for full gelatinization of the starch. A detailed examination revealed that this endotherm represented the melting of amylose-lipid complexes. Breadfruit starch paste exhibited shear-thinning fluid characteristics, and good thermal and pH stability. The setback viscosity of the breadfruit starch was lower than that of potato and corn starches. The rheological properties of the breadfruit starch paste was well described by the Herschel-Bulkley model at a shear rate of 0 to 100 s(-1), where R(2) is greater than 0.95, and it behaved like a yield-pseudoplastic fluid. Both the storage modulus and loss modulus of the paste initially increased sharply, then dropped after reaching the gelatinization peak. Breadfruit starch gel showed both flexibility and viscosity. Suspension with 6% starch content exhibited very weak gel rigidity; however, this increased significantly at starch contents above 20%.
Thermal protection materials: Thermophysical property data
NASA Technical Reports Server (NTRS)
Williams, S. D.; Curry, Donald M.
1992-01-01
This publication presents a thermophysical property survey on materials that could potentially be used for future spacecraft thermal protection systems (TPS). This includes data that was reported in the 1960's as well as more current information reported through the 1980's. An attempt was made to cite the manufacturers as well as the data source in the bibliography. This volume represents an attempt to provide in a single source a complete set of thermophysical data on a large variety of materials used in spacecraft TPS analysis. The property data is divided into two categories: ablative and reusable. The ablative materials have been compiled into twelve categories that are descriptive of the material composition. An attempt was made to define the Arrhenius equation for each material although this data may not be available for some materials. In a similar manner, char data may not be available for some of the ablative materials. The reusable materials have been divided into three basic categories: thermal protection materials (such as insulators), adhesives, and structural materials.
Thermal properties of hemp fibre non-woven materials
NASA Astrophysics Data System (ADS)
Freivalde, Liga; Kukle, Silvija; Russell, Stephen
2013-12-01
This review considers the thermal properties analysis of hemp fiber non-woven materials made by three different manufacturing technologies - thermal bonding, needle-punching and hydro-entanglement. For non-wovens development two hemp fibers cultivars grown in Latvia were used - Purini and Bialobrzeskie. Thermal resistance, conductivity and the effects of several parameters on thermal performance are revised.
Temperature-dependent thermal properties of supported MoS2 monolayers.
Taube, Andrzej; Judek, Jarosław; Łapińska, Anna; Zdrojek, Mariusz
2015-03-11
Thermal properties can substantially affect the operation of various electronics and optoelectronics devices based on two-dimensional materials. In this work, we describe our investigation of temperature-dependent thermal conductivity and interfacial thermal conductance of molybdenum disulfide monolayers supported on SiO2/Si substrates, using Raman spectroscopy. We observed that the calculated thermal conductivity (κ) and interfacial thermal conductance (g) decreased with increasing temperature from 62.2 W m(-1) K(-1) and 1.94 MW m(-2) K(-1) at 300 K to 7.45 W m(-1) K(-1) and 1.25 MW m(-2) K(-1) at 450 K, respectively.
Interactive calculations of thermodynamics properties of minerals in VLab
NASA Astrophysics Data System (ADS)
Kelly, N.; da Silveira, P. R.; Wentzcovitch, R. M.
2009-12-01
We have developed a page within the VLab web site from which calculations of thermodynamics properties of minerals can be performed interactively. Previously published first principles calculations based on qhasiharmonic theory by our group have produced pressure dependent vibrational density of states (VDOSs). These calculations were costly and the essential information they produced, the VDOSs, are now stored on a database. They can be used to regenerate published results or calculate thermodynamics properties using specific user entered information (pressure and temperature range and grids, equation of state type, etc). Results are presented in numerical or graphics format (Gnuplot 4.2.2) that are interactively customized and downloadable. All codes behind the Web container are written in Java.
NASA Astrophysics Data System (ADS)
Kaplun, Alexander; Meshalkin, Arkadiy
2014-08-01
The new simple semi empirical equation of state for description of P-ρ-T data of "normal" substances was specified. New equation of state has 10 individual adjustable coefficients and it describes thermal properties of gas, liquid and fluid in the main with the accuracy within the error of experimental data, except of critical region. The caloric properties and the speed of sound of argon, nitrogen and carbon dioxide were calculated with the help of known thermodynamic equations and in general divergences between calculated and tabular caloric data do not exceed the experimental error. New equation can be used for engineering calculations at the deficit of experimental data, especially on the caloric properties of substances.
Semiconductor nanowires: Controlled growth and thermal properties
NASA Astrophysics Data System (ADS)
Wu, Yiying
This dissertation presents an experimental study of the controlled growth of semiconductor nanowires and their thermophysical properties. The synthesis of nanowires was based on the well-known Vapor-Liquid-Solid (VLS) mechanism in which the growth of nanowire is initiated by a nanosized liquid droplet. The prepared nanowires are single-crystalline with certain preferred growth direction. Nanowires with different compositions have been synthesized, including Si, Ge, boron and MgB2. The control of nanowire composition, diameter and orientation has also been achieved. In addition, a Pulsed Laser Ablation-Chemical Vapor Deposition (PLA-CVD) hybrid process was developed to synthesize Si/SiGe longitudinally superlattice nanowires. The thermal conductivity of individual pure Si nanowire and Si/SiGe nanowire was measured using a microfabricated suspended device over a temperature range of 20--320 K. The thermal conductivities of individual 22, 37, 56, and 115 nm diameter single crystalline intrinsic Si nanowires were much lower than the bulk value due to the strong phonon boundary scattering. Except for the 22 nm diameter nanowire, theoretical predictions using a modified Callaway model fit the experimental data very well. The data for the 22 nm diameter wire suggest that changes in phonon dispersion due to confinement can cause additional thermal conductivity reduction. The Si/SiGe superlattice nanowires with diameters of 83 run and 58 nm were also measured. Their thermal conductivities are smaller than pure Si nanowire with similar diameter, as well as Si/SiGe superlattice thin film with comparable period. Both the alloying scattering and the boundary scattering are believed to contribute to this reduction. Size dependent melting-recrystallization study of the carbon-sheathed semiconductor Ge nanowires was carried out in in-situ high temperature transmission electron microscope (TEM). Significant depression in melting temperature with decreasing size of the nanowires as
Thermal properties of silicon nitride beams below one Kelvin.
Wang, G.; Yefremenko, V.; Novosad, V.; Datesman, A.; Pearson, J.; Divan, R.; Chang, C. L.; Bleem, L.; Crites, A. T.; Mehl, J.; Natoli, T.; McMahon, J.; Sayre, J.; Ruhl, J.; Meyer, S. S.; Carlstrom, J. E.
2011-06-01
We have investigated thermal properties of 1 {micro}m thick silicon nitride beams of different lateral dimensions. We measured the thermal conductance by simultaneously employing a TES both as a heater and as a sensor. Based upon these measurements, we calculate the thermal conductivity of the beams. We utilize a boundary limited phonon transport model and assume a temperature independent phonon mean free path. We find that the thermal conductivity is determined by the fraction of diffusive reflection at surface. The following results are obtained from 0.30 K to 0.55 K: the volume heat capacity is 0.082T+0.502T{sup 3} J/m{sup 3}-K . The width dependent phonon mean free path is 6.58 {micro}m, 9.80 {micro}m and 11.55 {micro}m for 10 {micro}m, 20 {micro}m and 30 {micro}m beams respectively at a 29% surface diffusive reflection.
Substructure Versus Property-Level Dispersed Modes Calculation
NASA Technical Reports Server (NTRS)
Stewart, Eric C.; Peck, Jeff A.; Bush, T. Jason; Fulcher, Clay W.
2016-01-01
This paper calculates the effect of perturbed finite element mass and stiffness values on the eigenvectors and eigenvalues of the finite element model. The structure is perturbed in two ways: at the "subelement" level and at the material property level. In the subelement eigenvalue uncertainty analysis the mass and stiffness of each subelement is perturbed by a factor before being assembled into the global matrices. In the property-level eigenvalue uncertainty analysis all material density and stiffness parameters of the structure are perturbed modified prior to the eigenvalue analysis. The eigenvalue and eigenvector dispersions of each analysis (subelement and property-level) are also calculated using an analytical sensitivity approximation. Two structural models are used to compare these methods: a cantilevered beam model, and a model of the Space Launch System. For each structural model it is shown how well the analytical sensitivity modes approximate the exact modes when the uncertainties are applied at the subelement level and at the property level.
Determination of Viral Capsid Elastic Properties from Equilibrium Thermal Fluctuations
NASA Astrophysics Data System (ADS)
May, Eric R.; Brooks, Charles L., III
2011-05-01
We apply two-dimensional elasticity theory to viral capsids to develop a framework for calculating elastic properties of viruses from equilibrium thermal fluctuations of the capsid surface in molecular dynamics and elastic network model trajectories. We show that the magnitudes of the long wavelength modes of motion available in a simulation with all atomic degrees of freedom are recapitulated by an elastic network model. For the mode spectra to match, the elastic network model must be scaled appropriately by a factor which can be determined from an icosahedrally constrained all-atom simulation. With this method we calculate the two-dimensional Young’s modulus Y, bending modulus κ, and Föppl-von Kármán number γ, for the T=1 mutant of the Sesbania mosaic virus. The values determined are in the range of previous theoretical estimates.
239Pu Resonance Evaluation for Thermal Benchmark System Calculations
Leal, Luiz C; Noguere, G; De Saint Jean, C; Kahler, A.
2013-01-01
Analyses of thermal plutonium solution critical benchmark systems have indicated a deciency in the 239Pu resonance evaluation. To investigate possible solutions to this issue, the Organisation for Economic Co-operation and Development (OECD) Nuclear Energy Agency (NEA) Working Party for Evaluation Cooperation (WPEC) established Subgroup 34 to focus on the reevaluation of the 239Pu resolved resonance parameters. In addition, the impacts of the prompt neutron multiplication (nubar) and the prompt neutron ssion spectrum (PFNS) have been investigated. The objective of this paper is to present the results of the 239Pu resolved resonance evaluation eort.
239Pu Resonance Evaluation for Thermal Benchmark System Calculations
NASA Astrophysics Data System (ADS)
Leal, L. C.; Noguere, G.; de Saint Jean, C.; Kahler, A. C.
2014-04-01
Analyses of thermal plutonium solution critical benchmark systems have indicated a deficiency in the 239Pu resonance evaluation. To investigate possible solutions to this issue, the Organisation for Economic Co-operation and Development (OECD) Nuclear Energy Agency (NEA) Working Party for Evaluation Cooperation (WPEC) established Subgroup 34 to focus on the reevaluation of the 239Pu resolved resonance parameters. In addition, the impacts of the prompt neutron multiplicity (νbar) and the prompt neutron fission spectrum (PFNS) have been investigated. The objective of this paper is to present the results of the 239Pu resolved resonance evaluation effort.
Calculation of the transport and relaxation properties of dilute water vapor
NASA Astrophysics Data System (ADS)
Hellmann, Robert; Bich, Eckard; Vogel, Eckhard; Dickinson, Alan S.; Vesovic, Velisa
2009-07-01
Transport properties of dilute water vapor have been calculated in the rigid-rotor approximation using four different potential energy hypersurfaces and the classical-trajectory method. Results are reported for shear viscosity, self-diffusion, thermal conductivity, and volume viscosity in the dilute-gas limit for the temperature range of 250-2500 K. Of these four surfaces the CC-pol surface of Bukowski et al. [J. Chem. Phys. 128, 094314 (2008)] is in best accord with the available measurements. Very good agreement is found with the most accurate results for viscosity in the whole temperature range of the experiments. For thermal conductivity the deviations of the calculated values from the experimental data increase systematically with increasing temperature to around 5% at 1100 K. For both self-diffusion and volume viscosity, the much more limited number of available measurements are generally consistent with the calculated values, apart from the lower temperature isotopically labeled diffusion measurements.
The spacing calculator software—A Visual Basic program to calculate spatial properties of lineaments
NASA Astrophysics Data System (ADS)
Ekneligoda, Thushan C.; Henkel, Herbert
2006-05-01
A software tool is presented which calculates the spatial properties azimuth, length, spacing, and frequency of lineaments that are defined by their starting and ending co-ordinates in a two-dimensional (2-D) planar co-ordinate system. A simple graphical interface with five display windows creates a user-friendly interactive environment. All lineaments are considered in the calculations, and no secondary sampling grid is needed for the elaboration of the spatial properties. Several rule-based decisions are made to determine the nearest lineament in the spacing calculation. As a default procedure, the programme defines a window that depends on the mode value of the length distribution of the lineaments in a study area. This makes the results more consistent, compared to the manual method of spacing calculation. Histograms are provided to illustrate and elaborate the distribution of the azimuth, length and spacing. The core of the tool is the spacing calculation between neighbouring parallel lineaments, which gives direct information about the variation of block sizes in a given category of structures. The 2-D lineament frequency is calculated for the actual area that is occupied by the lineaments.
THERMAL STRESS CALCULATIONS FOR HEATPIPE-COOLED REACTOR POWER SYSTEMS.
Kapernick, R. J.; Guffee, R. M.
2001-01-01
A heatpipe-cooled fast reactor concept has been under development at Los Alamos National Laboratory for the past several years, to be used as a power source for nuclear electric propulsion (NEP) or as a planetary surface power system. The reactor core consists of an array of modules that are held together by a core lateral restraint system. Each module comprises a single heatpipe surrounded by 3-6 clad fuel pins. As part of the design development and performance assessment activities for these reactors, specialized methods and models have been developed to perform thermal and stress analyses of the core modules. The methods have been automated so that trade studies can be readily performed, looking at design options such as module size, heatpipe and clad thickness, use of sleeves to contain the fuel, material type, etc. This paper describes the methods and models that have been developed, and presents thermal and stress analysis results for a Mars surface power system and a NEP power source.
First principles calculations of thermodynamical properties of cage-like silicon clathrate materials
NASA Astrophysics Data System (ADS)
Jack, Deslippe; Dong, Jianjun
2003-03-01
Si, Ge, and Sn based clathrate materials are potential high ZT thermoelectric materials due to their electron-crystal-phon-glass properties. Recently, the synthesis of guest-free type-II Si clathrate (Si136) was reported. The pristine (guest-free) Si and Ge clathrate can be viewed as "negative-pressure" phases, which might exist metastably at ambient conditions. In this talk, we will report our recent calculations of the thermodynamic properties of silicon type-I and -II Clathrate phases, as well as the ground state Si diamond phase. Statistical quasi-harmonic theory is used in conjunction with first-principles static bonding energy and dynamic phonon spectrum calculations to obtain free energies of the lattices. At zero temperature, the transition pressures of diamond-to-clathrate-I and diamond-to-clathrates-II transitions are predicted to be -46.9 kbar and -38.9 kbar respectively, while the Clapeyron slopes (dP/dT) of the two transitions at 300K are 8.64 bar/K and 7.38 bar/K respectively. Thermal properties of the Si materials, such as (linear) thermal expansion coefficients, Gruneisen parameters, heat capacities, and thermal bulk moduli etc. are also calculated. We find good agreement with experiment in the Si diamond phase. The results of the Si clathrates are discussed in comparison to those of the Si diamond, as well as available data of metal-encapsulated Si-based clathrate compounds (such as Na8Si46).
Composition, structure and properties of sediment thermal springs of Kamchatka
NASA Astrophysics Data System (ADS)
Shanina, Violetta; Smolyakov, Pavel; Parfenov, Oleg
2016-04-01
associated with the rise of mixed solutions, formed at the boundary of secondary boil through faults to the surface thermal boiler (Bortnikova et al., 2009). Calculated flow index and plasticity, shows the classification in accordance with GOST 25100-2011. From these figures it is clear that all the sediments are sandy loam and are in a fluid state. A clear relationship between temperature, pH and particle size distribution of sediment thermal springs can not be traced, great importance is the geological evolution of the volcanic activity, hydrogeological conditions and the time factor. Therefore, samples with a currently active Mutnovsky volcano - sandy loam, sediments of the thermal springs Koshelevo fields are often to loams. The bottom sediments of thermal springs from the territory of the Lower Koshelevo thermal field in a natural occurrence in a state of higher yield strength, so they are an unstable surface, which may cause landslides. The bottom sediments of thermal springs are low explored subject of engineering geology, it is important to examine their properties to simulate the conditions of formation and the development of dangerous processes.
Calculation of petrophysical properties for Mishrif carbonate reservoir
NASA Astrophysics Data System (ADS)
Kadhim, Fadhil Sarhan; Samsuri, Ariffin; Idris, Ahmad Kamal
2014-10-01
The accurate calculations of petrophysical properties in carbonate reservoirs are the most challenging aspects of well log analysis. Many equations have been developed over the years based on known physical principles or on empirically derived relationships, which are used to calculate carbonate rock petrophysical properties. Carbonate reservoirs in the Middle East are very heterogeneous in terms of rock types. Therefore the reservoir should be split into layers on the basis of the dominant rock type in order to define average values and trends of petrophysical parameters in the reservoir rock. The saturation exponent (n) and cementation exponent (m) are calculated from well log data using Pickett method. The study made across the Mishrif carbonate formation, which is the shallowest formation of the hydrocarbon bearing zone in the NS oil field in the Middle East. Results show that the average formation water resistivity (Rw= 0.0243), average mud filtrate resistivity (Rmf= 0.199), Irreducible Water Saturation (Swi=0. 18), and Archie's parameters (m=1. 78, n= 2, and a=1). While porosity, true resistivity, and water saturation values with depth of formation were calculated by using Interactive Petrophysics software (IP V3.5, 2008). The computer process interpretation (CPI) illustrates that the shale member splits the Mishrif formation into two parts; Upper and Lower Mishrif. This study is a step to investigate petrophysical properties, which used to calculate water saturation that should use to estimate original oil in place and detected the perforation zones.
Microcomputer Calculation of Thermodynamic Properties from Molecular Parameters of Gases.
ERIC Educational Resources Information Center
Venugopalan, Mundiyath
1990-01-01
Described in this article is a problem-solving activity which integrates the application of microcomputers with the learning of physical chemistry. Students use the program with spectroscopic data to calculate the thermodynamic properties and compare them with the values from the thermochemical tables. (Author/KR)
Calculation of thermal expansion coefficient of glasses based on topological constraint theory
NASA Astrophysics Data System (ADS)
Zeng, Huidan; Ye, Feng; Li, Xiang; Wang, Ling; Yang, Bin; Chen, Jianding; Zhang, Xianghua; Sun, Luyi
2016-10-01
In this work, the thermal expansion behavior and the structure configuration evolution of glasses were studied. Degree of freedom based on the topological constraint theory is correlated with configuration evolution; considering the chemical composition and the configuration change, the analytical equation for calculating the thermal expansion coefficient of glasses from degree of freedom was derived. The thermal expansion of typical silicate and chalcogenide glasses was examined by calculating their thermal expansion coefficients (TEC) using the approach stated above. The results showed that this approach was energetically favorable for glass materials and revealed the corresponding underlying essence from viewpoint of configuration entropy. This work establishes a configuration-based methodology to calculate the thermal expansion coefficient of glasses that, lack periodic order.
Using electron microscopy to calculate optical properties of biological samples.
Wu, Wenli; Radosevich, Andrew J; Eshein, Adam; Nguyen, The-Quyen; Yi, Ji; Cherkezyan, Lusik; Roy, Hemant K; Szleifer, Igal; Backman, Vadim
2016-11-01
The microscopic structural origins of optical properties in biological media are still not fully understood. Better understanding these origins can serve to improve the utility of existing techniques and facilitate the discovery of other novel techniques. We propose a novel analysis technique using electron microscopy (EM) to calculate optical properties of specific biological structures. This method is demonstrated with images of human epithelial colon cell nuclei. The spectrum of anisotropy factor g, the phase function and the shape factor D of the nuclei are calculated. The results show strong agreement with an independent study. This method provides a new way to extract the true phase function of biological samples and provides an independent validation for optical property measurement techniques.
Using electron microscopy to calculate optical properties of biological samples
Wu, Wenli; Radosevich, Andrew J.; Eshein, Adam; Nguyen, The-Quyen; Yi, Ji; Cherkezyan, Lusik; Roy, Hemant K.; Szleifer, Igal; Backman, Vadim
2016-01-01
The microscopic structural origins of optical properties in biological media are still not fully understood. Better understanding these origins can serve to improve the utility of existing techniques and facilitate the discovery of other novel techniques. We propose a novel analysis technique using electron microscopy (EM) to calculate optical properties of specific biological structures. This method is demonstrated with images of human epithelial colon cell nuclei. The spectrum of anisotropy factor g, the phase function and the shape factor D of the nuclei are calculated. The results show strong agreement with an independent study. This method provides a new way to extract the true phase function of biological samples and provides an independent validation for optical property measurement techniques. PMID:27896013
Thermal Properties of G-348 Graphite
McEligot, Donald; Swank, W. David; Cottle, David L.; Valentin, Francisco I.
2016-05-01
Fundamental measurements have been obtained in the INL Graphite Characterization Laboratory to deduce the temperature dependence of thermal conductivity for G-348 isotropic graphite, which has been used by City College of New York in thermal experiments related to gas-cooled nuclear reactors. Measurements of thermal diffusivity, mass, volume and thermal expansion were converted to thermal conductivity in accordance with ASTM Standard Practice C781-08. Data are tabulated and a preliminary correlation for the thermal conductivity is presented as a function of temperature from laboratory temperature to 1000C.
Consiglio, Anthony; Tian, Zhiting
2016-01-01
The wide bandgap semiconductor, ZnO, has gained interest recently as a promising option for use in power electronics such as thermoelectric and piezoelectric generators, as well as optoelectronic devices. Though much work has been done to improve its electronic properties, relatively little is known of its thermal transport properties with large variations in measured thermal conductivity. In this study, we examine the effects of a Hubbard corrected energy functional on the lattice thermal conductivity of wurtzite ZnO calculated using density functional theory and an iterative solution to the Boltzmann transport equation. Showing good agreement with existing experimental measurements, and with a detailed analysis of the mode-dependence and phonon properties, the results from this study highlight the importance of the Hubbard correction in calculations of thermal transport properties of materials with strongly correlated electron systems. PMID:27830737
Consiglio, Anthony; Tian, Zhiting
2016-11-10
The wide bandgap semiconductor, ZnO, has gained interest recently as a promising option for use in power electronics such as thermoelectric and piezoelectric generators, as well as optoelectronic devices. Though much work has been done to improve its electronic properties, relatively little is known of its thermal transport properties with large variations in measured thermal conductivity. In this study, we examine the effects of a Hubbard corrected energy functional on the lattice thermal conductivity of wurtzite ZnO calculated using density functional theory and an iterative solution to the Boltzmann transport equation. Showing good agreement with existing experimental measurements, and with a detailed analysis of the mode-dependence and phonon properties, the results from this study highlight the importance of the Hubbard correction in calculations of thermal transport properties of materials with strongly correlated electron systems.
NASA Astrophysics Data System (ADS)
Consiglio, Anthony; Tian, Zhiting
2016-11-01
The wide bandgap semiconductor, ZnO, has gained interest recently as a promising option for use in power electronics such as thermoelectric and piezoelectric generators, as well as optoelectronic devices. Though much work has been done to improve its electronic properties, relatively little is known of its thermal transport properties with large variations in measured thermal conductivity. In this study, we examine the effects of a Hubbard corrected energy functional on the lattice thermal conductivity of wurtzite ZnO calculated using density functional theory and an iterative solution to the Boltzmann transport equation. Showing good agreement with existing experimental measurements, and with a detailed analysis of the mode-dependence and phonon properties, the results from this study highlight the importance of the Hubbard correction in calculations of thermal transport properties of materials with strongly correlated electron systems.
Computer Programs for Calculating the Isentropic Flow Properties for Mixtures of R-134a and Air
NASA Technical Reports Server (NTRS)
Kvaternik, Raymond G.
2000-01-01
Three computer programs for calculating the isentropic flow properties of R-134a/air mixtures which were developed in support of the heavy gas conversion of the Langley Transonic Dynamics Tunnel (TDT) from dichlorodifluoromethane (R-12) to 1,1,1,2 tetrafluoroethane (R-134a) are described. The first program calculates the Mach number and the corresponding flow properties when the total temperature, total pressure, static pressure, and mole fraction of R-134a in the mixture are given. The second program calculates tables of isentropic flow properties for a specified set of free-stream Mach numbers given the total pressure, total temperature, and mole fraction of R-134a. Real-gas effects are accounted for in these programs by treating the gases comprising the mixture as both thermally and calorically imperfect. The third program is a specialized version of the first program in which the gases are thermally perfect. It was written to provide a simpler computational alternative to the first program in those cases where real-gas effects are not important. The theory and computational procedures underlying the programs are summarized, the equations used to compute the flow quantities of interest are given, and sample calculated results that encompass the operating conditions of the TDT are shown.
Galileo probe forebody thermal protection - Benchmark heating environment calculations
NASA Astrophysics Data System (ADS)
Balakrishnan, A.; Nicolet, W. E.
1981-06-01
Solutions are presented for the aerothermal heating environment for the forebody heatshield of candidate Galileo probe. Entry into both the nominal and cool-heavy model atmospheres were considered. Solutions were obtained for the candidate heavy probe with a weight of 310 kg and a lighter probe with a weight of 290 kg. In the flowfield analysis, a finite difference procedure was employed to obtain benchmark predictions of pressure, radiative and convective heating rates, and the steady-state wall blowing rates. Calculated heating rates for entry into the cool-heavy model atmosphere were about 60 percent higher than those predicted for the entry into the nominal atmosphere. The total mass lost for entry into the cool-heavy model atmosphere was about 146 kg and the mass lost for entry into the nominal model atmosphere was about 101 kg.
Galileo probe forebody thermal protection - Benchmark heating environment calculations
NASA Technical Reports Server (NTRS)
Balakrishnan, A.; Nicolet, W. E.
1981-01-01
Solutions are presented for the aerothermal heating environment for the forebody heatshield of candidate Galileo probe. Entry into both the nominal and cool-heavy model atmospheres were considered. Solutions were obtained for the candidate heavy probe with a weight of 310 kg and a lighter probe with a weight of 290 kg. In the flowfield analysis, a finite difference procedure was employed to obtain benchmark predictions of pressure, radiative and convective heating rates, and the steady-state wall blowing rates. Calculated heating rates for entry into the cool-heavy model atmosphere were about 60 percent higher than those predicted for the entry into the nominal atmosphere. The total mass lost for entry into the cool-heavy model atmosphere was about 146 kg and the mass lost for entry into the nominal model atmosphere was about 101 kg.
Optimal experimental designs for the estimation of thermal properties of composite materials
NASA Technical Reports Server (NTRS)
Scott, Elaine P.; Moncman, Deborah A.
1994-01-01
Reliable estimation of thermal properties is extremely important in the utilization of new advanced materials, such as composite materials. The accuracy of these estimates can be increased if the experiments are designed carefully. The objectives of this study are to design optimal experiments to be used in the prediction of these thermal properties and to then utilize these designs in the development of an estimation procedure to determine the effective thermal properties (thermal conductivity and volumetric heat capacity). The experiments were optimized by choosing experimental parameters that maximize the temperature derivatives with respect to all of the unknown thermal properties. This procedure has the effect of minimizing the confidence intervals of the resulting thermal property estimates. Both one-dimensional and two-dimensional experimental designs were optimized. A heat flux boundary condition is required in both analyses for the simultaneous estimation of the thermal properties. For the one-dimensional experiment, the parameters optimized were the heating time of the applied heat flux, the temperature sensor location, and the experimental time. In addition to these parameters, the optimal location of the heat flux was also determined for the two-dimensional experiments. Utilizing the optimal one-dimensional experiment, the effective thermal conductivity perpendicular to the fibers and the effective volumetric heat capacity were then estimated for an IM7-Bismaleimide composite material. The estimation procedure used is based on the minimization of a least squares function which incorporates both calculated and measured temperatures and allows for the parameters to be estimated simultaneously.
Electronic and thermal properties of Biphenyl molecules
NASA Astrophysics Data System (ADS)
Medina, F. G.; Ojeda, J. H.; Duque, C. A.; Laroze, D.
2015-11-01
Transport properties of a single Biphenyl molecule coupled to two contacts are studied. We characterise this system by a tight-binding Hamiltonian. Based on the non-equilibrium Green's functions technique with a Landauer-Büttiker formalism the transmission probability, current and thermoelectrical power are obtained. We show that the Biphenyl molecule may have semiconductor behavior for certain values of the electrode-molecule-electrode junctions and different values of the angle between the two rings of the molecule. In addition, the density of states (DOS) is calculated to compare the bandwidths with the profile of the transmission probability. DOS allows us to explain the asymmetric shape with respect to the molecule's Fermi energy.
Internet calculations of thermodynamic properties of substances: Some problems and results
NASA Astrophysics Data System (ADS)
Ustyuzhanin, E. E.; Ochkov, V. F.; Shishakov, V. V.; Rykov, S. V.
2016-11-01
Internet resources (databases, web sites and others) on thermodynamic properties R = (p,T,s,...) of technologically important substances are analyzed. These databases put online by a number of organizations (the Joint Institute for High Temperatures of the Russian Academy of Sciences, Standartinform, the National Institute of Standards and Technology USA, the Institute for Thermal Physics of the Siberian Branch of the Russian Academy of Sciences, etc) are investigated. Software codes are elaborated in the work in forms of “client functions” those have such characteristics: (i) they are placed on a remote server, (ii) they serve as open interactive Internet resources. A client can use them for a calculation of R properties of substances. “Complex client functions” are considered. They are focused on sharing (i) software codes elaborated to design of power plants (PP) and (ii) client functions those can calculate R properties of working fluids for PP.
First principles calculation of thermo-mechanical properties of thoria using Quantum ESPRESSO
NASA Astrophysics Data System (ADS)
Malakkal, Linu; Szpunar, Barbara; Zuniga, Juan Carlos; Siripurapu, Ravi Kiran; Szpunar, Jerzy A.
2016-05-01
In this work, we have used Quantum ESPRESSO (QE), an open source first principles code, based on density-functional theory, plane waves, and pseudopotentials, along with quasi-harmonic approximation (QHA) to calculate the thermo-mechanical properties of thorium dioxide (ThO2). Using Python programming language, our group developed qe-nipy-advanced, an interface to QE, which can evaluate the structural and thermo-mechanical properties of materials. We predicted the phonon contribution to thermal conductivity (kL) using the Slack model. We performed the calculations within local density approximation (LDA) and generalized gradient approximation (GGA) with the recently proposed version for solids (PBEsol). We employed a Monkhorst-Pack 5 × 5 × 5 k-points mesh in reciprocal space with a plane wave cut-off energy of 150 Ry to obtain the convergence of the structure. We calculated the dynamical matrices of the lattice on a 4 × 4 × 4 mesh. We have predicted the heat capacity, thermal expansion and the phonon contribution to thermal conductivity, as a function of temperature up to 1400K, and compared them with the previous work and known experimental results.
Impacts of doping on thermal and thermoelectric properties of nanomaterials.
Zhang, Gang; Li, Baowen
2010-07-01
Thermal transport in nanoscale structures has attracted an increasing interest in the last two decades. On the one hand, the low dimensional nanostructured materials are platforms for testing novel phonon transport theories. On the other hand, nanomaterials are promising candidates for nanoscale on-chip coolers. This review is focused on the thermal conductance, thermoelectric property, and impacts of doping on these properties.
Predicting the properties of the lead alloys from DFT calculations
Buimaga-Iarinca, L. Calborean, A.
2015-12-23
We provide qualitative results for the physical properties of the lead alloys at atomic scale by using DFT calculations. Our approach is based on the two assumptions: (i) the geometric structure of lead atoms provides a matrix where the alloying elements can take their positions in the structure as substitutions and (ii) there is a small probability of a direct interaction between the alloying elements, thus the interactions of each alloying element may be approximated by the interactions to the lead matrix. DFT calculations are used to investigate the interaction between several types of impurities and the lead matrix for low concentrations of the alloying element. We report results such as the enthalpy of formation, charge transfer and mechanical stress induced by the impurities in the lead matrix; these results can be used as qualitative guide in tuning the physico-chemical properties of the lead alloys.
Thermal Coatings Seminar Series Training Part 1: Properties of Thermal Coatings
NASA Technical Reports Server (NTRS)
Triolo, Jack
2015-01-01
This course will present an overview of a variety of thermal coatings-related topics, including: coating types and availability, thermal properties measurements, environmental testing (lab and in-flight), environmental impacts, contamination impacts, contamination liabilities, determination of BOLEOL values, and what does specularity mean to the thermal engineer.
Thermoelectric Properties of Half-Heusler Heterostructures from Ab Initio Calculations
NASA Astrophysics Data System (ADS)
Fiedler, Gregor; Kratzer, Peter
2016-03-01
Semiconducting half-Heusler alloys have recently emerged as a class of thermoelectric materials with outstanding performance in the medium- to high-temperature range. Heterostructures promise a further reduction of thermal conductivity as a result of phonon scattering at interfaces. Here, both the electronic and phononic spectra of half-Heusler compounds based on Ti, Zr, and Hf are calculated using density functional theory. With this input, thermoelectric properties are obtained, and the thermal conductivity of a heterostructure superlattice is estimated by extending the diffuse mismatch model of interface conductance. We find that a high power factor σ S^2 can be retained in a short-period superlattice, while thermal conductivity is reduced compared to that in single-phase half-Heusler crystals.
Thermal-optical properties of Fluorel L-3203-6 and 1059
NASA Technical Reports Server (NTRS)
French, B.
1972-01-01
Fluorel L-3203-6 and 1059 and four Fluorel derivatives were irradiated monochromatically and hemispherically with electromagnetic energy in the solar- and infrared-wavelength range to determine the thermal-optical properties that are required for engineering analysis. The thermal-optical properties were measured and analyzed, and the resulting data were tabulated for convenient engineering use. The results prove that the electromagnetic-energy distribution and the measured reflectance and transmittance of materials can be used to calculate several mean values, which are the total and hemispherical thermal-optical properties. The test results also illustrate that Fluorel effectively absorbs energy in the solar- and infrared-wavelength range. In addition, the results demonstrate that fabrication alters the thermal-optical properties of Fluorel.
Influence of saturation properties on shell-model calculations
NASA Astrophysics Data System (ADS)
Abzouzi, A.; Caurier, E.; Zuker, A. P.
1991-03-01
It is shown that the nuclear Hamiltonian scrH separates rigorously into a monopole field scrHm and a multipole part scrHm. scrHm is entirely responsible for saturation properties and can be treated phenomenologically with few parameters. When realistic interactions are used for scrHM in regions from the p shell to the N=82 isotones, shell-model calculations yield excellent spectroscopy and demand nuclear radii very close to the observed ones.
AUTOSTRUCTURE: General program for calculation of atomic and ionic properties
NASA Astrophysics Data System (ADS)
Badnell, Nigel R.
2016-12-01
AUTOSTRUCTURE calculates atomic and ionic energy levels, radiative rates, autoionization rates, photoionization cross sections, plane-wave Born and distorted-wave excitation cross sections in LS- and intermediate-coupling using non- or (kappa-averaged) relativistic wavefunctions. These can then be further processed to form Auger yields, fluorescence yields, partial and total dielectronic and radiative recombination cross sections and rate coefficients, photoabsorption cross sections, and monochromatic opacities, among other properties.
Study of the thermal stability of studtite by in situ Raman spectroscopy and DFT calculations
NASA Astrophysics Data System (ADS)
Colmenero, Francisco; Bonales, Laura J.; Cobos, Joaquín; Timón, Vicente
2017-03-01
The design of a safe spent nuclear fuel repository requires the knowledge of the stability of the secondary phases which precipitate when water reaches the fuel surface. Studtite is recognized as one of the secondary phases that play a key-role in the mobilization of the radionuclides contained in the spent fuel. Thereby, it has been identified as a product formed under oxidation conditions at the surface of the fuel, and recently found as a corrosion product in the Fukushima-Daiichi nuclear plant accident. Thermal stability is one of the properties that should be determined due to the high temperature of the fuel. In this work we report a detailed analysis of the structure and thermal stability of studtite. The structure has been studied both by experimental techniques (SEM, TGA, XRD and Raman spectroscopy) and theoretical DFT electronic structure and spectroscopic calculations. The comparison of the results allows us to perform for the first time the Raman bands assignment of the whole spectrum. The thermal stability of studtite has been analyzed by in situ Raman spectroscopy, with the aim of studying the effect of the heating rate and the presence of water. For this purpose, a new cell has been designed. The results show that studtite is stable under dry conditions only at temperatures below 30 °C, in contrast with the higher temperatures published up to date ( 130 °C). Opposite behaviour has been found when studtite is in contact with water; under these conditions studtite is stable up to 90 °C, what is consistent with the encounter of this phase after the Fukushima-Daiichi accident.
NASA Astrophysics Data System (ADS)
Landry, E. S.; McGaughey, A. J. H.
2009-10-01
The accuracies of two theoretical expressions for thermal boundary resistance are assessed by comparing their predictions to independent predictions from molecular dynamics (MD) simulations. In one expression (RE) , the phonon distributions are assumed to follow the equilibrium, Bose-Einstein distribution, while in the other expression (RNE) , the phonons are assumed to have nonequilibrium, but bulk-like distributions. The phonon properties are obtained using lattice dynamics-based methods, which assume that the phonon interface scattering is specular and elastic. We consider (i) a symmetrically strained Si/Ge interface, and (ii) a series of interfaces between Si and “heavy-Si,” which differs from Si only in mass. All of the interfaces are perfect, justifying the assumption of specular scattering. The MD-predicted Si/Ge thermal boundary resistance is temperature independent and equal to 3.1×10-9m2-K/W below a temperature of ˜500K , indicating that the phonon scattering is elastic, as required for the validity of the theoretical calculations. At higher-temperatures, the MD-predicted Si/Ge thermal boundary resistance decreases with increasing temperature, a trend we attribute to inelastic scattering. For the Si/Ge interface and the Si/heavy-Si interfaces with mass ratios greater than two, RE is in good agreement with the corresponding MD-predicted values at temperatures where the interface scattering is elastic. When applied to a system containing no interface, RE is erroneously nonzero due to the assumption of equilibrium phonon distributions on either side of the interface. While RNE is zero for a system containing no interface, it is 40%-60% less than the corresponding MD-predicted values for the Si/Ge interface and the Si/heavy-Si interfaces at temperatures where the interface scattering is elastic. This inaccuracy is attributed to the assumption of bulk-like phonon distributions on either side of the interface.
Study of the thermal stability of studtite by in situ Raman spectroscopy and DFT calculations.
Colmenero, Francisco; Bonales, Laura J; Cobos, Joaquín; Timón, Vicente
2017-03-05
The design of a safe spent nuclear fuel repository requires the knowledge of the stability of the secondary phases which precipitate when water reaches the fuel surface. Studtite is recognized as one of the secondary phases that play a key-role in the mobilization of the radionuclides contained in the spent fuel. Thereby, it has been identified as a product formed under oxidation conditions at the surface of the fuel, and recently found as a corrosion product in the Fukushima-Daiichi nuclear plant accident. Thermal stability is one of the properties that should be determined due to the high temperature of the fuel. In this work we report a detailed analysis of the structure and thermal stability of studtite. The structure has been studied both by experimental techniques (SEM, TGA, XRD and Raman spectroscopy) and theoretical DFT electronic structure and spectroscopic calculations. The comparison of the results allows us to perform for the first time the Raman bands assignment of the whole spectrum. The thermal stability of studtite has been analyzed by in situ Raman spectroscopy, with the aim of studying the effect of the heating rate and the presence of water. For this purpose, a new cell has been designed. The results show that studtite is stable under dry conditions only at temperatures below 30°C, in contrast with the higher temperatures published up to date (~130°C). Opposite behaviour has been found when studtite is in contact with water; under these conditions studtite is stable up to 90°C, what is consistent with the encounter of this phase after the Fukushima-Daiichi accident.
Calculated optical properties of thorium, protactinium, and uranium metals
Gasche, T.; Brooks, M.S.; Johansson, B.
1996-07-01
We report self-consistent energy band calculations using the linear muffin-tin orbital method and the local-spin-density approximation to exchange and correlation in density-functional theory for the light actinide metals Th, Pa, and U. The optical properties have been calculated and compared with measurements, where possible. The dependence of the optical response functions upon crystal structure was found to be surprisingly large and the dependence upon spin-orbit coupling, less so. Where it was possible to make comparison, agreement with experiment was obtained for the maxima of the optical spectra, the exception being a feature in the optical conductivity at 10 eV measured in both Th and U but not obtained in the calculations. {copyright} {ital 1996 The American Physical Society.}
Cavern/Vault Disposal Concepts and Thermal Calculations for Direct Disposal of 37-PWR Size DPCs
Hardin, Ernest; Hadgu, Teklu; Clayton, Daniel James
2015-03-01
This report provides two sets of calculations not presented in previous reports on the technical feasibility of spent nuclear fuel (SNF) disposal directly in dual-purpose canisters (DPCs): 1) thermal calculations for reference disposal concepts using larger 37-PWR size DPC-based waste packages, and 2) analysis and thermal calculations for underground vault-type storage and eventual disposal of DPCs. The reader is referred to the earlier reports (Hardin et al. 2011, 2012, 2013; Hardin and Voegele 2013) for contextual information on DPC direct disposal alternatives.
Membrane protein properties revealed through data-rich electrostatics calculations
Guerriero, Christopher J.; Brodsky, Jeffrey L.; Grabe, Michael
2015-01-01
SUMMARY The electrostatic properties of membrane proteins often reveal many of their key biophysical characteristics, such as ion channel selectivity and the stability of charged membrane-spanning segments. The Poisson-Boltzmann (PB) equation is the gold standard for calculating protein electrostatics, and the software APBSmem enables the solution of the PB equation in the presence of a membrane. Here, we describe significant advances to APBSmem including: full automation of system setup, per-residue energy decomposition, incorporation of PDB2PQR, calculation of membrane induced pKa shifts, calculation of non-polar energies, and command-line scripting for large scale calculations. We highlight these new features with calculations carried out on a number of membrane proteins, including the recently solved structure of the ion channel TRPV1 and a large survey of 1,614 membrane proteins of known structure. This survey provides a comprehensive list of residues with large electrostatic penalties for being embedded in the membrane potentially revealing interesting functional information. PMID:26118532
Calculations and curve fits of thermodynamic and transport properties for equilibrium air to 30000 K
NASA Technical Reports Server (NTRS)
Gupta, Roop N.; Lee, Kam-Pui; Thompson, Richard A.; Yos, Jerrold M.
1991-01-01
A self-consistent set of equilibrium air values were computed for enthalpy, total specific heat at constant pressure, compressibility factor, viscosity, total thermal conductivity, and total Prandtl number from 500 to 30,000 K over a range of 10(exp -4) atm to 10(exp 2) atm. The mixture values are calculated from the transport and thermodynamic properties of the individual species provided in a recent study by the authors. The concentrations of the individual species, required in the mixture relations, are obtained from a free energy minimization calculation procedure. Present calculations are based on an 11-species air model. For pressures less than 10(exp -2) atm and temperatures of about 15,000 K and greater, the concentrations of N(++) and O(++) become important, and consequently, they are included in the calculations determining the various properties. The computed properties are curve fitted as a function of temperature at a constant value of pressure. These curve fits reproduce the computed values within 5 percent for the entire temperature range considered here at specific pressures and provide an efficient means for computing the flowfield properties of equilibrium air, provided the elemental composition remains constant at 0.24 for oxygen and 0.76 for nitrogen by mass.
Kan, An-Kang; Cao, Dan; Zhang, Xue-Lai
2015-04-01
Accurately predicting the effective thermal conductivity of the fibrous materials is highly desirable but remains to be a challenging work. In this paper, the microstructure of the porous fiber materials is analyzed, approximated and modeled on basis of the statistical self-similarity of fractal theory. A fractal model is presented to accurately calculate the effective thermal conductivity of fibrous porous materials. Taking the two-phase heat transfer effect into account, the existing statistical microscopic geometrical characteristics are analyzed and the Hertzian Contact solution is introduced to calculate the thermal resistance of contact points. Using the fractal method, the impacts of various factors, including the porosity, fiber orientation, fractal diameter and dimension, rarified air pressure, bulk thermal conductivity coefficient, thickness and environment condition, on the effective thermal conductivity, are analyzed. The calculation results show that the fiber orientation angle caused the material effective thermal conductivity to be anisotropic, and normal distribution is introduced into the mathematic function. The effective thermal conductivity of fibrous material increases with the fiber fractal diameter, fractal dimension and rarefied air pressure within the materials, but decreases with the increase of vacancy porosity.
Thermal properties of rocks of the borehole Yaxcopoil-1 (Impact Crater Chicxulub, Mexico)
NASA Astrophysics Data System (ADS)
Popov, Yu.; Romushkevich, R.; Korobkov, D.; Mayr, S.; Bayuk, I.; Burkhardt, H.; Wilhelm, H.
2011-02-01
The results of thermal property measurements on cores from the scientific well Yaxcopoil-1 (1511 m in depth) drilled in the Chicxulub impact structure (Mexico) are described. The thermal conductivity, thermal diffusivity, volumetric heat capacity, thermal anisotropy coefficient, thermal heterogeneity factor, and, in addition, porosity and density were measured on 451 dry and water-saturated cores from the depth interval of 404-1511 m. The acoustic velocities were determined on a subgroup of representative samples. Significant vertical short- and long-scale variations of physical properties related to the grade of shock-thermal metamorphism and correlations between thermal and other physical properties are established. Rocks of the post-impact and impact complexes differ significantly in heterogeneity demonstrating that the impact complex has larger micro- heterogeneity on sample scale. The pre-impact rocks differ essentially from the impact and post-impact rocks in the thermal conductivity, thermal diffusivity, density and porosity. The thermal anisotropy of rocks of all structural-lithological complexes is very low (K = 1.02 … 1.08), which is similar to the situation in the Puchezh-Katunk and Ries impact structures. Correlations are established between the thermal conductivity and elastic wave velocities measured in laboratory. For limestone-calcarenites, the thermal conductivity (λ) can be calculated from the compressional wave velocity (Vp) using the formula λ= 0.346 Vp + 0.844, and for dolomite-anhydrites this relation has the form λ= 0.998 Vp + 1.163 [for λ in W (m K)-1 and Vp in km s-1]. These correlations are used for downscaling of the sonic velocities to the decimetre scale. The effective medium theory is applied to invert the matrix thermal conductivity and pore/crack geometry from the thermal conductivity measured on the studied samples. Representative experimental data on the thermal properties for all lithological groups encountered by the
Mechanical properties of thermal protection system materials.
Hardy, Robert Douglas; Bronowski, David R.; Lee, Moo Yul; Hofer, John H.
2005-06-01
An experimental study was conducted to measure the mechanical properties of the Thermal Protection System (TPS) materials used for the Space Shuttle. Three types of TPS materials (LI-900, LI-2200, and FRCI-12) were tested in 'in-plane' and 'out-of-plane' orientations. Four types of quasi-static mechanical tests (uniaxial tension, uniaxial compression, uniaxial strain, and shear) were performed under low (10{sup -4} to 10{sup -3}/s) and intermediate (1 to 10/s) strain rate conditions. In addition, split Hopkinson pressure bar tests were conducted to obtain the strength of the materials under a relatively higher strain rate ({approx}10{sup 2} to 10{sup 3}/s) condition. In general, TPS materials have higher strength and higher Young's modulus when tested in 'in-plane' than in 'through-the-thickness' orientation under compressive (unconfined and confined) and tensile stress conditions. In both stress conditions, the strength of the material increases as the strain rate increases. The rate of increase in LI-900 is relatively small compared to those for the other two TPS materials tested in this study. But, the Young's modulus appears to be insensitive to the different strain rates applied. The FRCI-12 material, designed to replace the heavier LI-2200, showed higher strengths under tensile and shear stress conditions. But, under a compressive stress condition, LI-2200 showed higher strength than FRCI-12. As far as the modulus is concerned, LI-2200 has higher Young's modulus both in compression and in tension. The shear modulus of FRCI-12 and LI-2200 fell in the same range.
Thermal properties of nonstoichiometry uranium dioxide
NASA Astrophysics Data System (ADS)
Kavazauri, R.; Pokrovskiy, S. A.; Baranov, V. G.; Tenishev, A. V.
2016-04-01
In this paper, was developed a method of oxidation pure uranium dioxide to a predetermined deviation from the stoichiometry. Oxidation was carried out using the thermogravimetric method on NETZSCH STA 409 CD with a solid electrolyte galvanic cell for controlling the oxygen potential of the environment. 4 samples uranium oxide were obtained with a different ratio of oxygen-to-metal: O / U = 2.002, O / U = 2.005, O / U = 2.015, O / U = 2.033. For the obtained samples were determined basic thermal characteristics of the heat capacity, thermal diffusivity, thermal conductivity. The error of heat capacity determination is equal to 5%. Thermal diffusivity and thermal conductivity of the samples decreased with increasing deviation from stoichiometry. For the sample with O / M = 2.033, difference of both values with those of stoichiometric uranium dioxide is close to 50%.
NASA Astrophysics Data System (ADS)
Chen, C. Z.; Wen, N. Y.; Chen, H. J.; Li, Y.; Cai, C. B.
2017-02-01
Tungsten (W)-doped SnO2 is investigated by first-principle calculations, with a view to understand the effect of doping on the lattice structure, thermal stability, conductivity, and optical transparency. Due to the slight difference in ionic radius as well as high thermal and chemical compatibility between the native element and the heterogeneous dopant, the doped system changes a little with different deviations in the lattice constant from Vegard's law, and good thermal stability is observed as the doping level reaches x = 0.125 in Sn1- x W x O2 compounds. Nevertheless, the large disparities in electron configuration and electronegativity between W and Sn atoms will dramatically modify the electronic structure and charge distribution of W-doped SnO2, leading to a remarkable enhancement of conductivity, electron excitation in the low energy region, and the consequent optical properties, while the visible transparency of Sn1 -x W x O2 is still preserved. Particularly, it is found that the optimal photoelectric properties of W-doped SnO2 may be achieved at x = 0.03. These observations are consistent with the experimental results available on the structural, thermal, electronic, and optical properties of Sn1- x W x O2, thus presenting a practical way of tailoring the physical behaviors of SnO2 through the doping technique.
Synthesis and thermal properties of new bionanofluids containing gold nanoparticles
NASA Astrophysics Data System (ADS)
Jiménez-Pérez, J. L.; López Gamboa, G.; Gutiérrez Fuentes, R.; Sánchez Ramírez, J. F.; Correa Pacheco, Z. N.; López-y-López, V. E.; Tepech-Carrillo, L.
2016-10-01
New bionanofluids containing Au nanoparticles with different concentrations were prepared by chemical reduction method. The nanoparticles were mixed with biodiesel from soybean prepared using alkaline catalysts. Thermal properties of biodiesel containing Au nanoparticles with different volume percentage concentrations were measured by mismatched dual-beam mode thermal lens technique in order to measure the effect of the presence of nanoparticles ( φ = 13.3 nm) on the bionanofluids thermal diffusivity. The characteristic time constant of the transient thermal lens was estimated by fitting the experimental data to the theoretical expression for transient thermal lens. The thermal diffusivity of the bionanofluids (biodiesel containing Au nanoparticles) seems to be strongly dependent on the presence of nanoparticles. It was observed an increase in the thermal diffusivity when volume percentage of nanoparticles increased. A possible explanation for such high thermal diffusivity of the biodiesel with Au nanoparticles is given. UV-Vis spectroscopy and TEM microscopy techniques were used to characterize the bionanofluids.
Measurement of Thermal Properties of Biosourced Building Materials
NASA Astrophysics Data System (ADS)
Pierre, Thomas; Colinart, Thibaut; Glouannec, Patrick
2014-10-01
This paper presents both experimental and theoretical works concerning the evaluation of the thermal conductivity and thermal diffusivity of hemp concrete. Experimental measurements of thermal properties are performed using a hot-strip technique for temperatures ranging from 3 to 30 and relative humidities ranging from 0 % to 95 %, thus creating a large database for this material. These experimental thermal conductivities are then compared with the results from the Krischer theoretical predictive model. The comparison shows good agreement, and a predictive analytical relation between the hemp concrete thermal conductivity, temperature, and relative humidity is determined.
Property-optimized gaussian basis sets for molecular response calculations.
Rappoport, Dmitrij; Furche, Filipp
2010-10-07
With recent advances in electronic structure methods, first-principles calculations of electronic response properties, such as linear and nonlinear polarizabilities, have become possible for molecules with more than 100 atoms. Basis set incompleteness is typically the main source of error in such calculations since traditional diffuse augmented basis sets are too costly to use or suffer from near linear dependence. To address this problem, we construct the first comprehensive set of property-optimized augmented basis sets for elements H-Rn except lanthanides. The new basis sets build on the Karlsruhe segmented contracted basis sets of split-valence to quadruple-zeta valence quality and add a small number of moderately diffuse basis functions. The exponents are determined variationally by maximization of atomic Hartree-Fock polarizabilities using analytical derivative methods. The performance of the resulting basis sets is assessed using a set of 313 molecular static Hartree-Fock polarizabilities. The mean absolute basis set errors are 3.6%, 1.1%, and 0.3% for property-optimized basis sets of split-valence, triple-zeta, and quadruple-zeta valence quality, respectively. Density functional and second-order Møller-Plesset polarizabilities show similar basis set convergence. We demonstrate the efficiency of our basis sets by computing static polarizabilities of icosahedral fullerenes up to C(720) using hybrid density functional theory.
NASA Astrophysics Data System (ADS)
Landerville, Aaron C.; Oleynik, Ivan I.
2017-01-01
Dispersion Corrected Density Functional Theory (DFT+vdW) calculations are performed to predict vibrational and thermal properties of the bulk energetic materials (EMs) β-octahydrocyclotetramethylene-tetranitramine (β-HMX) and triaminotrinitrobenzene (TATB). DFT+vdW calculations of pressure-dependent crystal structure and the hydrostatic equation of state are followed by frozen-phonon calculations of their respective vibration spectra at each pressure. These are then used under the quasi-harmonic approximation to obtain zero-point and thermal free energy contributions to the pressure, resulting in pressure-volume-temperature (PVT) EOS for each material that are in excellent agreement with experiment. Heat capacities, and coefficients of thermal expansion as functions of temperature are also calculated and compared with experiment.
Non-Equilibrium Properties from Equilibrium Free Energy Calculations
NASA Technical Reports Server (NTRS)
Pohorille, Andrew; Wilson, Michael A.
2012-01-01
Calculating free energy in computer simulations is of central importance in statistical mechanics of condensed media and its applications to chemistry and biology not only because it is the most comprehensive and informative quantity that characterizes the eqUilibrium state, but also because it often provides an efficient route to access dynamic and kinetic properties of a system. Most of applications of equilibrium free energy calculations to non-equilibrium processes rely on a description in which a molecule or an ion diffuses in the potential of mean force. In general case this description is a simplification, but it might be satisfactorily accurate in many instances of practical interest. This hypothesis has been tested in the example of the electrodiffusion equation . Conductance of model ion channels has been calculated directly through counting the number of ion crossing events observed during long molecular dynamics simulations and has been compared with the conductance obtained from solving the generalized Nernst-Plank equation. It has been shown that under relatively modest conditions the agreement between these two approaches is excellent, thus demonstrating the assumptions underlying the diffusion equation are fulfilled. Under these conditions the electrodiffusion equation provides an efficient approach to calculating the full voltage-current dependence routinely measured in electrophysiological experiments.
Vitruk, S.G.; Korsun, A.S.; Ushakov, P.A.
1995-09-01
The multilevel mathematical model of neutron thermal hydrodynamic processes in a passive safety core without assemblies duct walls and appropriate computer code SKETCH, consisted of thermal hydrodynamic module THEHYCO-3DT and neutron one, are described. A new effective discretization technique for energy, momentum and mass conservation equations is applied in hexagonal - z geometry. The model adequacy and applicability are presented. The results of the calculations show that the model and the computer code could be used in conceptual design of advanced reactors.
Development of MATLAB Scripts for the Calculation of Thermal Manikin Regional Resistance Values
2016-01-01
and a file organization structure is recommended to run the scripts efficiently . A feature in the thermal manikin software that performs similar...calculations is acknowledged and compared to the scripts. The ultimate goal is to improve the accuracy and efficiency of preparing raw thermal manikin...was developed for a particular file organization system , it is recommended to use the file organization structure shown in Figure 1 which is also
Unified expression for the calculation of thermal conductivity in the canonical ensemble
NASA Astrophysics Data System (ADS)
Chialvo, Ariel A.; Cummings, Peter T.
A proof of the theoretical equivalence between the E. Helfand, 1960, Phys. Rev., 119, 1 and the D. McQuarrie, 1976, Statistical Mechanics (Harper & Row), Chap. 21 equations for the calculation of thermal conductivity via the Einsteintype relations is presented here. Some theoretical implications of that equivalence are also discussed, such as the unification of the thermal conductivity expressions into one similar to that given for linear transport coefficients by F. C. Andrews, 1967, J. Chem. Phys., 47, 3161.
Thermal Properties of Methane Hydrate by Experiment and Modeling and Impacts on Technology
Warzinski, R.P.; Gamwo, I.K.; Rosenbaum, E.M.; Jiang, Hao; Jordan, K.D.; English, N.J.; Shaw, D.W.
2008-07-01
Thermal properties of pure methane hydrate, under conditions similar to naturally occurring hydrate-bearing sediments being considered for potential production, have been determined both by a new experimental technique and by advanced molecular dynamics simulation (MDS). A novel single-sided, Transient Plane Source (TPS) technique has been developed and used to measure thermal conductivity and thermal diffusivity values of low-porosity methane hydrate formed in the laboratory. The experimental thermal conductivity data are closely matched by results from an equilibrium MDS method using in-plane polarization of the water molecules. MDS was also performed using a non-equilibrium model with a fully polarizable force field for water. The calculated thermal conductivity values from this latter approach were similar to the experimental data. The impact of thermal conductivity on gas production from a hydrate-bearing reservoir was also evaluated using the Tough+/Hydrate reservoir simulator.
High-accuracy coupled cluster calculations of atomic properties
NASA Astrophysics Data System (ADS)
Borschevsky, A.; Yakobi, H.; Eliav, E.; Kaldor, U.
2015-01-01
The four-component Fock-space coupled cluster and intermediate Hamiltonian methods are implemented to evaluate atomic properties. The latter include the spectra of nobelium and lawrencium (elements 102 and 103) in the range 20000-30000 cm-1, the polarizabilities of elements 112-114 and 118, required for estimating their adsorption enthalpies on surfaces used to separate them in accelerators, and the nuclear quadrupole moments of some heavy atoms. The calculations on superheavy elements are supported by the very good agreement with experiment obtained for the lighter homologues.
High-accuracy coupled cluster calculations of atomic properties
Borschevsky, A.; Yakobi, H.; Eliav, E.; Kaldor, U.
2015-01-22
The four-component Fock-space coupled cluster and intermediate Hamiltonian methods are implemented to evaluate atomic properties. The latter include the spectra of nobelium and lawrencium (elements 102 and 103) in the range 20000-30000 cm{sup −1}, the polarizabilities of elements 112-114 and 118, required for estimating their adsorption enthalpies on surfaces used to separate them in accelerators, and the nuclear quadrupole moments of some heavy atoms. The calculations on superheavy elements are supported by the very good agreement with experiment obtained for the lighter homologues.
Calculation evaluation of multiplying properties of LWR with thorium fuel
NASA Astrophysics Data System (ADS)
Shamanin, I. V.; Grachev, V. M.; Knyshev, V. V.; Bedenko, S. V.; Novikova, N. G.
2017-01-01
The results of multiplying properties design research of the unit cell and LWR fuel assembly with the high temperature gas-cooled thorium reactor fuel pellet are presented in the work. The calculation evaluation showed the possibility of using thorium in LWR effectively. In this case the amount of fissile isotope is 2.45 times smaller in comparison with the standard loading of LWR. The research and numerical experiments were carried out using the verified accounting code of the program MCU5, modern libraries of evaluated nuclear data and multigroup approximations.
Electronic, thermal and mechanical properties of carbon nanotubes.
Dresselhaus, M S; Dresselhaus, G; Charlier, J C; Hernández, E
2004-10-15
A review of the electronic, thermal and mechanical properties of nanotubes is presented, with particular reference to properties that differ from those of the bulk counterparts and to potential applications that might result from the special structure and properties of nanotubes. Both experimental and theoretical aspects of these topics are reviewed.
Thermal Properties of Degenerate Relativistic Quantum Gases
NASA Astrophysics Data System (ADS)
Homorodean, Laurean
We present the concentration-temperature phase diagram, characteristic functions, thermal equation of state and heat capacity at constant volume for degenerate ideal gases of relativistic fermions and bosons. The nonrelativistic and ultrarelativistic limits of these laws are also discussed.
NASA Glenn Coefficients for Calculating Thermodynamic Properties of Individual Species
NASA Technical Reports Server (NTRS)
McBride, Bonnie J.; Zehe, Michael J.; Gordon, Sanford
2002-01-01
This report documents the library of thermodynamic data used with the NASA Glenn computer program CEA (Chemical Equilibrium with Applications). This library, containing data for over 2000 solid, liquid, and gaseous chemical species for temperatures ranging from 200 to 20,000 K, is available for use with other computer codes as well. The data are expressed as least-squares coefficients to a seven-term functional form for C((sup o)(sub p)) (T) / R with integration constants for H (sup o) (T) / RT and S(sup o) (T) / R. The NASA Glenn computer program PAC (Properties and Coefficients) was used to calculate thermodynamic functions and to generate the least-squares coefficients. PAC input was taken from a variety of sources. A complete listing of the database is given along with a summary of thermodynamic properties at 0 and 298.15 K.
Mechanical and Thermal Properties of Praseodymium Monopnictides: AN Ultrasonic Study
NASA Astrophysics Data System (ADS)
Bhalla, Vyoma; Kumar, Raj; Tripathy, Chinmayee; Singh, Devraj
2013-09-01
We have computed ultrasonic attenuation, acoustic coupling constants and ultrasonic velocities of praseodymium monopnictides PrX(X: N, P, As, Sb and Bi) along the <100>, <110>, <111> in the temperature range 100-500 K using higher order elastic constants. The higher order elastic constants are evaluated using Coulomb and Born-Mayer potential with two basic parameters viz. nearest-neighbor distance and hardness parameter in the temperature range of 0-500 K. Several other mechanical and thermal parameters like bulk modulus, shear modulus, Young's modulus, Poisson ratio, anisotropic ratio, tetragonal moduli, Breazeale's nonlinearity parameter and Debye temperature are also calculated. In the present study, the fracture/toughness (B/G) ratio is less than 1.75 which implies that PrX compounds are brittle in nature at room temperature. The chosen material fulfilled Born criterion of mechanical stability. We also found the deviation of Cauchy's relation at higher temperatures. PrN is most stable material as it has highest valued higher order elastic constants as well as the ultrasonic velocity. Further, the lattice thermal conductivity using modified approach of Slack and Berman is determined at room temperature. The ultrasonic attenuation due to phonon-phonon interaction and thermoelastic relaxation mechanisms have been computed using modified Mason's approach. The results with other well-known physical properties are useful for industrial applications.
Cassini CAPS Measurements of Thermal Ion Properties: An Update
NASA Astrophysics Data System (ADS)
Wilson, R. J.; Bagenal, F.; Delamere, P. A.
2010-12-01
Since the Wilson et al. [2008] paper on thermal ion properties in Saturn's inner equatorial magnetosphere there have been several advances in forward model techniques and instrument knowledge. These include: a) Improved CAPS (SNG) calibration values since 2008. While the previous fits to data are still valid, this efficiency adjustment has the effect of reducing the density values calculated from that fit. Compared to the previous calibration values, nOH+ and nH+ are ≈30% and ≈9% lower respectively. b) Robust error analysis on the forward model process to produce standard deviations for the fitted parameters. This also shows the expected dependences between various fitted parameters, such as Vφ and OH+ T⊥, inherent in the model. c) Utilization of real magnetic field data to forward model T⊥ and T\\par. Previously assumed magnetic field was in the -z direction. In addition, these improvements allow us to remove the constraint that Vz = 0, and the use of real magnetic field data allows us to analyze data farther from the equator. References Wilson, R. J., R. L. Tokar, M. G. Henderson, T. W. Hill, M. F. Thomsen, and D. H. Pontius (2008), Cassini plasma spectrometer thermal ion measurements in Saturn's inner magnetosphere,
Deformation and Thermal Properties of Energetic Materials.
1980-12-01
decomposition of PETN/polymer samples 5 (b) Thermal decomposition of PETN/ Benzoyl peroxide samples ......... 6 (c) Effect of ultra-violet light on... Benzoyl peroxide samples The results of the preceeding section show that the additives tested have very little effect on the thermal decomposition of PETN...nitrate. In order to test this hypothesis, mixtures of benzoyl peroxide and PETN were used in a series of TG experiments. Benzoyl peroxide is an
Thermal state of SNPS Topaz'' units: Calculation basing and experimental confirmation
Bogush, I.P.; Bushinsky, A.V.; Galkin, A.Y.; Serbin, V.I.; Zhabotinsky, E.E. )
1991-01-01
The ensuring thermal state parameters of thermionic space nuclear power system (SNPS) units in required limits on all operating regimes is a factor which determines SNPSs lifetime. The requirements to unit thermal state are distinguished to a marked degree, and both the corresponding units arragement in SNPS power generating module and the use of definite control algorithms, special thermal regulation and protection are neccessary for its provision. The computer codes which permit to define the thermal transient performances of liquid metal loop and main units had been elaborated for calculation basis of required SNPS Topaz'' unit thermal state. The conformity of these parameters to a given requirements are confirmed by results of autonomous unit tests, tests of mock-ups, power tests of ground SNPS prototypes and flight tests of two SNPS Topaz''.
Investigation of thermal properties of raw materials of asphalt mixtures
NASA Astrophysics Data System (ADS)
Géber, R.; Simon, A.; Kocserha, I.
2017-02-01
Asphalt mixtures are composite materials, which are made of different grades of mineral aggregates and bitumen. During the mixing process mineral materials were blended with bitumen at relatively high temperature (∼200 °C). As the binding process come off in these higher temperature range, thermal properties of asphaltic materials are important. The aim of this project is to reveal the thermal properties of raw materials. During our research two types of mineral aggregates were tested (limestone and dolomite) by different methods. Differential thermal analysis, thermal expansion and thermal conductivity were investigated at technologically important temperatures. The results showed that the structure of mineral materials did not change at elevated temperatures, expansion of samples was neglible, while thermal conductivity changed by temperature.
Novel applications exploiting the thermal properties of nanostructured materials.
Eastman, J. A.
1998-11-20
A new class of heat transfer fluids, termed nanofluids, has been developed by suspending nanocrystalline particles in liquids. Due to the orders-of-magnitude larger thermal conductivities of solids compared to those of liquids such as water, significantly enhanced thermal properties are obtained with nanofluids. The use of nanofluids could impact many industrial sectors, including transportation, energy supply and production, electronics, textiles, and paper production by, for example, decreasing pumping power needs or reducing heat exchanger sizes. In contrast to the enhancement in effective thermal transport rates that is obtained when nanoparticles are suspended in fluids, nanocrystalline coatings are expected to exhibit reduced thermal conductivities compared to coarse-grained coatings. Reduced thermal conductivities are predicted to arise because of a reduction in the mean free path of phonons due to presence of grain boundaries. This behavior, combined with improved mechanical properties, makes nanostructured zirconia coatings excellent candidates for future applications as thermal barriers.
Bogoliubov-normal interaction and calculation of thermal conductivity of superfluid A1-3He
NASA Astrophysics Data System (ADS)
Afzali, R.; Ebrahimian, N.
2006-09-01
The diffusive thermal conductivity tensor of the A 1-phase of superfluid 3He at low temperatures and melting pressure are calculated by s-p approximation, by using the Boltzmann equation approach. We obtain that the elements of the diffusive thermal conductivities, Kxx, Kyy, and Kzz, are proportional to T -1. Then we compare the results of this paper and our results of thermal conductivity based on Pfitzner procedure. Temperature dependence of both results is equal but numerical coefficients of them are little different. Also we show that Boguliubov-normal interaction is important in comparison to other interactions.
Techniques for achieving thermal equilibrium in molecular dynamics calculations for solids
NASA Astrophysics Data System (ADS)
Wu, Ernest Yue; Friauf, Robert J.
1990-06-01
We develop techniques for achieving thermal equilibrium in molecular dynamics calculations for solids. Atoms in a Lennard-Jones solid are initially given random velocities and displacements from their equilibrium positions with suitably scaled Maxwellian distributions. A quantitative criterion for thermal equilibrium of the solid is established by using the equipartition of energy theorem. At high temperatures, thermal expansion is studied, and we introduce a method for adjusting the lattice parameter to ensure zero external pressure. The results of molecular dynamics simulations show agreement with experimental data for rare gas and ionic crystals.
Thermal properties of epoxy composites filled with boric acid
NASA Astrophysics Data System (ADS)
Visakh, P. M.; Nazarenko, O. B.; Amelkovich, Yu A.; Melnikova, T. V.
2015-04-01
The thermal properties of epoxy composites filled with boric acid fine powder at different percentage were studied. Epoxy composites were prepared using epoxy resin ED-20, boric acid as flame-retardant filler, hexamethylenediamine as a curing agent. The prepared samples and starting materials were examined using methods of thermal analysis, scanning electron microscopy and infrared spectroscopy. It was found that the incorporation of boric acid fine powder enhances the thermal stability of epoxy composites.
Thermophysical Properties of Polymer Materials with High Thermal Conductivity
NASA Astrophysics Data System (ADS)
Lebedev, S. M.; Gefle, O. S.; Dneprovskii, S. N.; Amitov, E. T.
2015-06-01
Results of studies on the main thermophysical properties of new thermally conductive polymer materials are presented. It is shown that modification of polymer dielectrics by micron-sized fillers allows thermally conductive materials with thermal conductivity not less than 2 W/(m K) to be produced, which makes it possible to use such materials as cooling elements of various electrical engineering and semiconductor equipment and devices.
Calculation of effective transport properties of partially saturated gas diffusion layers
NASA Astrophysics Data System (ADS)
Bednarek, Tomasz; Tsotridis, Georgios
2017-02-01
A large number of currently available Computational Fluid Dynamics numerical models of Polymer Electrolyte Membrane Fuel Cells (PEMFC) are based on the assumption that porous structures are mainly considered as thin and homogenous layers, hence the mass transport equations in structures such as Gas Diffusion Layers (GDL) are usually modelled according to the Darcy assumptions. Application of homogenous models implies that the effects of porous structures are taken into consideration via the effective transport properties of porosity, tortuosity, permeability (or flow resistance), diffusivity, electric and thermal conductivity. Therefore, reliable values of those effective properties of GDL play a significant role for PEMFC modelling when employing Computational Fluid Dynamics, since these parameters are required as input values for performing the numerical calculations. The objective of the current study is to calculate the effective transport properties of GDL, namely gas permeability, diffusivity and thermal conductivity, as a function of liquid water saturation by using the Lattice-Boltzmann approach. The study proposes a method of uniform water impregnation of the GDL based on the "Fine-Mist" assumption by taking into account the surface tension of water droplets and the actual shape of GDL pores.
Water absorbance and thermal properties of sulfated wheat gluten films
Technology Transfer Automated Retrieval System (TEKTRAN)
Wheat gluten films of varying thicknesses formed at 30C to 70C were treated with cold sulfuric acid to produce sulfated gluten films. Chemical, thermal, thermal stability, and water uptake properties were characterized for neat and sulfated films. The sulfated gluten films were able ...
Thermal properties of organic and modified inorganic aerogels
Pekala, R.W.; Hrubesh, L.W.
1992-08-01
Aerogels are open-cell foams that have already been shown to be among the best thermal insulating solid materials known. Improvements in the thermal insulating properties of aerogels are possible by synthesizing new organic varieties, by using additives within existing aerogel matrix, and by optimizing their nanostructures. We discuss these approaches and give some examples of aerogels which demonstrate the improvements.
A computer program to calculate radiation properties of reflector antennas
NASA Technical Reports Server (NTRS)
Agrawal, P. K.
1978-01-01
A computer program to calculate the radiation properties of the reflector antennas is presented. It can be used for paraboloidal, spherical, or ellipsoidal reflector surfaces and is easily modified to handle any surface that can be expressed analytically. The program is general enough to allow any arbitrary location and pointing angle for the feed antenna. The effect of blockage due to the feed horn is also included in the computations. The computer program is based upon the technique of tracing the rays from the feed antenna to the reflector to an aperture plane. The far field radiation properties are then calculated by performing a double integration over the field points in the aperture plane. To facilitate the computation of double intergral, the field points are first aligned along the equispaced straight lines in the aperture plane. The computation time is relatively insensitive to the absolute size of the aperture and even though no limits on the largest reflector size have been determined, the program was used for reflector diameters of 1000 wavelenghts.
Simultaneous Measurements of Thermal Properties of Individual Carbon Fibers
NASA Astrophysics Data System (ADS)
Wang, Jianli; Song, Bai; Zhang, Xing; Song, Yang; Wu, Gangping
2011-05-01
Combining the steady-state and quasi-steady-state T type probes, the longitudinal thermal conductivity and thermal effusivity of individual mesophase pitch-based carbon fiber heat treated at 2800 °C and 1000 °C have been measured from 100 K to 300 K. The present method allows simultaneous measurements of thermal properties using the same instrument, by simply changing the applied direct current to alternating current. The specific heat is found to decrease with increasing heat-treatment temperature and to approach the value of graphite. The highly graphitized carbon fiber has a maximum thermal conductivity of 410 W · m-1 · K-1 at about 250 K, and its thermal diffusivity decreases with increasing temperature. Comparatively, the thermal conductivity of the fiber heat treated at 1000 °C is much smaller, with the peak shifting to high temperature due to a large defect density, and its thermal diffusivity is nearly temperature independent.
Insights into Asteroid Thermal Properties from Lunar Eclipse Observations
NASA Astrophysics Data System (ADS)
Hayne, Paul; Lucey, Paul G.; Paige, David A.
2015-08-01
Surface temperatures on airless planetary bodies are controlled primarily by insolation and the thermophysical properties of the subsurface layer probed by the diurnal and seasonal thermal waves. Observations of asteroid thermal emission are used to constrain the physical structure of this surface layer. However, the thermal skin depth probed by this technique depends on rotation period, and the derived thermal inertia is a weighted average over a finite depth, which varies from one asteroid to another. If the properties of the surface layer are depth-dependent, then physically identical bodies with different rotation periods will have different apparent thermal inertia values. The Moon provides an opportunity to investigate this phenomenon, using thermal infrared emission curves on both the diurnal and eclipse timescales.We used multi-spectral thermal infrared observations of the Moon from two instruments: The Maui Space Surveillance System’s Longwave-IR (LWIR) imager, and the Lunar Reconnaissance Orbiter’s Diviner Lunar Radiometer. Diviner’s near-complete characterization of the lunar diurnal temperature cycles are used to constrain the properties of the uppermost √κt ~ 30 cm, where κ is thermal diffusivity and t is the rotation period. Eclipse cooling data from both LWIR and Diviner reveal the properties of the uppermost ~ 1 cm. Here, we focus on results from the October, 2014, and April, 2015 total lunar eclipses.Using a 1-d thermal model with depth-dependent thermal properties, we fit both the diurnal and eclipse brightness temperature data. Results show that the regolith thermal inertia increases exponentially with depth, from ~10 J m-2 K-1 s-1/2 at the surface to ~90 J m-2 K-1 s-1/2 at > 30 cm depth. This range brackets values derived from thermal light curves of many asteroids. Surface thermal inertia values derived from eclipse data are ~25 - 50% lower than previous models based on diurnal temperatures alone, and are similar to the lower end of
Calculation of atomic structures and radiative properties of fusion plasmas
NASA Astrophysics Data System (ADS)
Jarrah, Walid; Pain, Jean-Christophe; Benredjem, Djamel
2017-03-01
The opacity is an important issue in the knowledge of the radiative properties of Inertial Confinement Fusion (ICF) and astrophysical plasmas. In this work we present the opacity of the mixture C+Si, composing the ablator of some ICF capsules. We have used Cowan's code to calculate the atomic structure of carbon and silicon. We also have developed a collisional-radiative model in order to obtain the opacity of the mixture. Line broadening, line shift and ionization potential depression are taken into account in the opacity profile. Comparisons to other calculations are carried out. NLTE and LTE opacity calculations show discrepancies mainly in the range 1900-2000 eV for the bound-bound contribution to the total opacity and in the range 50-350 eV for the bound-free contribution. We have also accounted for photoexcitation and photoionization processes. The corresponding rates are obtained by modeling the Hohlraum radiation by a Planckian distribution at a radiative temperature of 300 eV.
NASA Astrophysics Data System (ADS)
Sangeetha, V.; Govindarajan, M.; Kanagathara, N.; Gunasekaran, S.; Rajakumar, P. R.; Anbalagan, G.
2014-06-01
Single crystals of melaminium bis (hydrogen oxalate) (MOX) were grown by slow evaporation method. X-ray powder diffraction analysis indicates that MOX crystallizes in monoclinic system (space group C2/c) and the calculated lattice constants are a = 20.075 ± 0.123 Ǻ, b = 8.477 ± 0.045 Ǻ, c = 6.983 ± 0.015, α = γ 90° and β = 102.6 ± 0.33°. Thermal analysis confirms that MOX is thermally stable up to 250 °C. A detailed interpretation of the FT-IR, FT-Raman and NMR spectra were reported. The equilibrium geometry, bonding features, and harmonic vibrational frequencies have been investigated with the help of PM6, HF and DFT/B3LYP methods. The potential energy curve shows that MOX molecule has two stable structures and the computational results diagnose that Rot I is the most stable conformer. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the Gauge-Invariant Atomic Orbital (GIAO) method. Stability of the molecule, arising from hyperconjugative interactions and charge delocalization, has been analyzed using Natural Bond Orbital (NBO) analysis. The electronic properties, such as HOMO and LUMO energies, were calculated by Time-Dependent DFT (TD-DFT) approach. To estimate chemical reactivity of the molecule, the molecular electrostatic potential (MEP) surface map is calculated for the optimized geometry of the molecule.
Ab Initio Calculations and Measurements of Thermoelectric Properties of V2O5 Films
NASA Astrophysics Data System (ADS)
Chumakov, Yu.; Xiong, S.-Y.; Santos, J. R.; Ferreira, I.; Termentzidis, K.; Pokropivny, A.; Cortona, P.; Volz, S.
2013-07-01
Density functional theory and the Boltzmann transport equation were used to calculate the thermoelectric transport coefficients for bulk V2O5 and MV2O5 (M = Cr, Ti, Na, Li). The structural relaxation for the given compounds based on the ABINIT code was observed. The temperature dependences of the Seebeck coefficients as well as electrical and thermal electrical conductivities of all relaxed structures displayed anisotropic behavior. Electrooptical measurements of thermoelectric properties were carried out on V2O5 thin films obtained by thermal evaporation with different post-annealing treatments. A Seebeck coefficient of -148 μV/K at T = 300 K was obtained in the in-plane direction for V2O5 thin films with thickness less than 100 nm.
Measurement of thermal properties of white radish (R. raphanistrum) using easily constructed probes
Obot, Mfrekemfon Samuel; Li, Changcheng; Fang, Ting; Chen, Jinquan
2017-01-01
Thermal properties are necessary for the design and control of processes and storage facilities of food materials. This study proposes the measurement of thermal properties using easily constructed probes with specific heat capacity calculated, as opposed to the use of Differential Scanning Calorimeter (DSC) or other. These probes were constructed and used to measure thermal properties of white radish in the temperature range of 80–20°C and moisture content of 91–6.1% wb. Results showed thermal properties were within the range of 0.71–0.111 Wm-1 C-1 for thermal conductivity, 1.869×10−7–0.72×10−8 m2s-1 for thermal diffusivity and 4.316–1.977 kJ kg-1C-1for specific heat capacity. These results agree with reports for similar products studied using DSC and commercially available line heat source probes. Empirical models were developed for each property through linear multiple regressions. The data generated would be useful in modeling and control of its processing and equipment design. PMID:28288175
THERMAL PROPERTIES OF SECONDARY ORGANIC AEROSOLS
Volume concentrations of steady-state secondary organic aerosol (SOA) were measured in several hydrocarbon/NO_{x} irradiation experiments. These measurements were used to estimate the thermal behavior of the particles that may be formed in the atmosphere. These laborator...
Thermal transport properties of metal/MoS{sub 2} interfaces from first principles
Mao, Rui; Kong, Byoung Don; Kim, Ki Wook
2014-07-21
Thermal transport properties at the metal/MoS{sub 2} interfaces are analyzed by using an atomistic phonon transport model based on the Landauer formalism and first-principles calculations. The considered structures include chemisorbed Sc(0001)/MoS{sub 2} and Ru(0001)/MoS{sub 2}, physisorbed Au(111)/MoS{sub 2}, as well as Pd(111)/MoS{sub 2} with intermediate characteristics. Calculated results illustrate a distinctive dependence of thermal transfer on the details of interfacial microstructures. More specifically, the chemisorbed case with a stronger bonding exhibits a generally smaller interfacial thermal resistance than the physisorbed. Comparison between metal/MoS{sub 2} and metal/graphene systems suggests that metal/MoS{sub 2} is significantly more resistive. Further examination of lattice dynamics identifies the presence of multiple distinct atomic planes and bonding patterns at the interface as the key origins of the observed large thermal resistance.
A biharmonic relaxation method for calculating thermal stress in cooled irregular cylinders
NASA Technical Reports Server (NTRS)
Holms, Arthur G
1952-01-01
A numerical method was developed for calculating thermal stresses in irregular cylinders cooled by one or more internal passages. The use of relaxation methods and elementary methods of finite differences was found to give approximations to the correct values when compared with previously known solutions for concentric circular cylinders possessing symmetrical and asymmetrical temperature distributions.
NASA Astrophysics Data System (ADS)
Gopal Muraleedharan, Murali; Srinivas Sundaram, Dilip; Henry, Asegun; Yang, Vigor
2017-04-01
The presence of artificial correlations associated with Green–Kubo (GK) thermal conductivity calculations is investigated. The thermal conductivity of nano-suspensions is calculated by equilibrium molecular dynamics (EMD) simulations using GK relations. Calculations are first performed for a single alumina (Al2O3) nanoparticle dispersed in a water medium. For a particle size of 1 nm and volume fraction of 9%, results show enhancements as high as 235%, which is much higher than the Maxwell model predictions. When calculations are done with multiple suspended particles, no such anomalous enhancement is observed. This is because the vibrations in alumina crystal can act as low frequency perturbations, which can travel long distances through the surrounding water medium, characterized by higher vibration frequencies. As a result of the periodic boundaries, they re-enter the system resulting in a circular resonance of thermal fluctuations between the alumina particle and its own image, eventually leading to artificial correlations in the heat current autocorrelation function (HCACF), which when integrated yields abnormally high thermal conductivities. Adding more particles presents ‘obstacles’ with which the fluctuations interact and get dissipated, before they get fed back to the periodic image. A systematic study of the temporal evolution of HCACF indicates that the magnitude and oscillations of artificial correlations decrease substantially with increase in the number of suspended nanoparticles.
Muraleedharan, Murali Gopal; Sundaram, Dilip; Henry, Asegun; Yang, Vigor
2017-02-07
The presence of artificial correlations associated with Green-Kubo (GK) thermal conductivity calculations is investigated. The thermal conductivity of nano-suspensions is calculated by equilibrium molecular dynamics (EMD) simulations using GK relations. Calculations are first performed for a single alumina (Al2O3) nanoparticle dispersed in a water medium. For a particle size of 1 nm and volume fraction of 9%, results show enhancements as high as 235%, which is much higher than the Maxwell model predictions. When calculations are done with multiple suspended particles, no such anomalous enhancement is observed. This is because the vibrations in alumina crystal can act as low frequency perturbations, which can travel long distances through the surrounding water medium, characterized by higher vibration frequencies. As a result of the periodic boundaries, they re-enter the system resulting in a circular resonance of thermal fluctuations between the alumina particle and its own image, eventually leading to artificial correlations in the heat current autocorrelation function (HCACF), which when integrated yields abnormally high thermal conductivities. Adding more particles presents 'obstacles' with which the fluctuations interact and get dissipated, before they get fed back to the periodic image. A systematic study of the temporal evolution of HCACF indicates that the magnitude and oscillations of artificial correlations decrease substantially with increase in the number of suspended nanoparticles.
Thermal conductivity and other properties of cementitious grouts
Allan, M.
1998-08-01
The thermal conductivity and other properties cementitious grouts have been investigated in order to determine suitability of these materials for grouting vertical boreholes used with geothermal heat pumps. The roles of mix variables such as water/cement ratio, sand/cement ratio and superplasticizer dosage were measured. In addition to thermal conductivity, the cementitious grouts were also tested for bleeding, permeability, bond to HDPE pipe, shrinkage, coefficient of thermal expansion, exotherm, durability and environmental impact. This paper summarizes the results for selected grout mixes. Relatively high thermal conductivities were obtained and this leads to reduction in predicted bore length and installation costs. Improvements in shrinkage resistance and bonding were achieved.
THERMAL CONDUCTIVITY AND OTHER PROPERTIES OF CEMENTITIOUS GROUTS
ALLAN,M.
1998-05-01
The thermal conductivity and other properties cementitious grouts have been investigated in order to determine suitability of these materials for grouting vertical boreholes used with geothermal heat pumps. The roles of mix variables such as water/cement ratio, sand/cement ratio and superplasticizer dosage were measured. In addition to thermal conductivity, the cementitious grouts were also tested for bleeding, permeability, bond to HDPE pipe, shrinkage, coefficient of thermal expansion, exotherm, durability and environmental impact. This paper summarizes the results for selected grout mixes. Relatively high thermal conductivities were obtained and this leads to reduction in predicted bore length and installation costs. Improvements in shrinkage resistance and bonding were achieved.
Review of thermal properties of graphite composite materials
Kourtides, D.A.
1987-12-01
Flammability, thermal, and selected mechanical properties of composites fabricated with epoxy and other thermally stable resin matrices are described. Properties which were measured included limiting-oxygen index, smoke evolution, thermal degradation products, total-heat release, heat-release rates, mass loss, flame spread, ignition resistance, thermogravimetric analysis, and selected mechanical properties. The properties of 8 different graphite composite panels fabricated using four different resin matrices and two types of graphite reinforcement are described. The resin matrices included: XU71775/H795, a blend of vinyl polystyryl pyridine and bismaleimide; H795, a bismaleimide; Cycom 6162, a phenolic; and PSP 6022M, a polystyryl pyridine. The graphite fiber used was AS-4 in the form of either tape or fabric. The properties of these composites were compared with epoxy composites. It was determined that the blend of vinyl polystyryl pyridine and bismaleimide (XU71775/H795) with the graphite tape was the optimum design giving the lowest heat release rate.
Review of thermal properties of graphite composite materials
NASA Technical Reports Server (NTRS)
Kourtides, D. A.
1987-01-01
Flammability, thermal, and selected mechanical properties of composites fabricated with epoxy and other thermally stable resin matrices are described. Properties which were measured included limiting-oxygen index, smoke evolution, thermal degradation products, total-heat release, heat-release rates, mass loss, flame spread, ignition resistance, thermogravimetric analysis, and selected mechanical properties. The properties of 8 different graphite composite panels fabricated using four different resin matrices and two types of graphite reinforcement are described. The resin matrices included: XU71775/H795, a blend of vinyl polystyryl pyridine and bismaleimide; H795, a bismaleimide; Cycom 6162, a phenolic; and PSP 6022M, a polystyryl pyridine. The graphite fiber used was AS-4 in the form of either tape or fabric. The properties of these composites were compared with epoxy composites. It was determined that the blend of vinyl polystyryl pyridine and bismaleimide (XU71775/H795) with the graphite tape was the optimum design giving the lowest heat release rate.
Use of thermal-inertia properties for material identification
NASA Technical Reports Server (NTRS)
Schieldge, J. P.; Kahle, A. B.; Alley, R. E.; Gillespie, A. R.
1980-01-01
It is noted that a knowledge of the thermal inertia of the earth's surface can be used in geologic mapping as a complement to surface reflectance data as provided by Landsat. Thermal inertia, which is a body property, cannot be determined directly but can be inferred from radiation temperature measurements made at various times in the diurnal heating cycle, combined with a model of the surface heating processes. A model of this type is developed and applied along with temperature measurements made in the field and by satellite to determine thermal properties of surface materials. An example from a test site in western Nevada is used to demonstrate the utility of this technique.
In situ thermally reduced graphene oxide/epoxy composites: thermal and mechanical properties
NASA Astrophysics Data System (ADS)
Olowojoba, Ganiu B.; Eslava, Salvador; Gutierrez, Eduardo S.; Kinloch, Anthony J.; Mattevi, Cecilia; Rocha, Victoria G.; Taylor, Ambrose C.
2016-10-01
Graphene has excellent mechanical, thermal, optical and electrical properties and this has made it a prime target for use as a filler material in the development of multifunctional polymeric composites. However, several challenges need to be overcome to take full advantage of the aforementioned properties of graphene. These include achieving good dispersion and interfacial properties between the graphene filler and the polymeric matrix. In the present work, we report the thermal and mechanical properties of reduced graphene oxide/epoxy composites prepared via a facile, scalable and commercially viable method. Electron micrographs of the composites demonstrate that the reduced graphene oxide (rGO) is well dispersed throughout the composite. Although no improvements in glass transition temperature, tensile strength and thermal stability in air of the composites were observed, good improvements in thermal conductivity (about 36 %), tensile and storage moduli (more than 13 %) were recorded with the addition of 2 wt% of rGO.
NASA Astrophysics Data System (ADS)
Kheyri, A.; Nourbakhsh, Z.
2016-09-01
The thermal properties of pure graphene and graphene-impurity (impurity = Fe, Co, Si, and Ge) sheets have been investigated at various pressures (0-7 GPa) and temperatures (0-900 K). Some basic thermodynamic quantities such as bulk modulus, coefficient of volume thermal expansion, heat capacities at constant pressure and constant volume of these sheets as a function of temperature and pressure are discussed. Furthermore, the effect of the impurity density and tensile strain on the thermodynamic properties of these sheets are investigated. All of these calculations are performed based on the density functional theory and full quasi harmonic approximation.
NASA Astrophysics Data System (ADS)
Zhang, Ping; Wang, Bao-Tian; Zhao, Xian-Geng
2010-10-01
Plutonium dioxide is of high technological importance in nuclear fuel cycle and is particularly crucial in long-term storage of Pu-based radioactive waste. Using first-principles density-functional theory, in this paper we systematically study the structural, electronic, mechanical, thermodynamic properties, and pressure-induced structural transition of PuO2 . To properly describe the strong correlation in Pu5f electrons, the local-density approximation (LDA)+U and the generalized gradient approximation+U theoretical formalisms have been employed. We optimize U parameter in calculating the total energy, lattice parameters, and bulk modulus at nonmagnetic, ferromagnetic, and antiferromagnetic configurations for both ground-state fluorite structure and high-pressure cotunnite structure. Best agreement with experiments is obtained by tuning the effective Hubbard parameter U at around 4 eV within LDA+U approach. After carefully testing the validity of the ground-state calculation, we further investigate the bonding nature, elastic constants, various moduli, Debye temperature, hardness, ideal tensile strength, and phonon dispersion for fluorite PuO2 . Some thermodynamic properties, e.g., Gibbs free energy, volume thermal expansion, and specific heat are also calculated. As for cotunnite phase, besides elastic constants, various moduli, and Debye temperature at 0 GPa, we have further presented our calculated electronic, structural, and magnetic properties for PuO2 under pressure up to 280 GPa. A metallic transition at around 133 GPa and an isostructural transition in pressure range of 75-133 GPa are predicted. Additionally, as an illustration on the valency trend and subsequent effect on the mechanical properties, the calculated results for other actinide metal dioxides ( ThO2 , UO2 , and NpO2 ) are also presented.
NASA Astrophysics Data System (ADS)
Valdes, Raymond
The characterization of thermal barrier coating (TBC) systems is increasingly important because they enable gas turbine engines to operate at high temperatures and efficiency. Phase of photothermal emission analysis (PopTea) has been developed to analyze the thermal behavior of the ceramic top-coat of TBCs, as a nondestructive and noncontact method for measuring thermal diffusivity and thermal conductivity. Most TBC allocations are on actively-cooled high temperature turbine blades, which makes it difficult to precisely model heat transfer in the metallic subsystem. This reduces the ability of rote thermal modeling to reflect the actual physical conditions of the system and can lead to higher uncertainty in measured thermal properties. This dissertation investigates fundamental issues underpinning robust thermal property measurements that are adaptive to non-specific, complex, and evolving system characteristics using the PopTea method. A generic and adaptive subsystem PopTea thermal model was developed to account for complex geometry beyond a well-defined coating and substrate system. Without a priori knowledge of the subsystem characteristics, two different measurement techniques were implemented using the subsystem model. In the first technique, the properties of the subsystem were resolved as part of the PopTea parameter estimation algorithm; and, the second technique independently resolved the subsystem properties using a differential "bare" subsystem. The confidence in thermal properties measured using the generic subsystem model is similar to that from a standard PopTea measurement on a "well-defined" TBC system. Non-systematic bias-error on experimental observations in PopTea measurements due to generic thermal model discrepancies was also mitigated using a regression-based sensitivity analysis. The sensitivity analysis reported measurement uncertainty and was developed into a data reduction method to filter out these "erroneous" observations. It was found
Thermal transmission at Si/Ge interface: ab initio lattice dynamics calculation
NASA Astrophysics Data System (ADS)
Alkurdi, A.; Merabia, S.
2017-01-01
We perform lattice dynamics calculations (LD) on silicon/germanium interfaces using ab initio interatomic force constants to predict the interfacial phonon transmission as a function of both phonon frequency and the transmission angle. We carry out a spectral and angular analysis to quantify the contribution of each phonon mode in a given scattering direction. The effect of the interaction range was studied at this interface by taking account of more or less atom layers across the interface. Moreover, we were able to predict the thermal boundary conductance (TBC) as a function of the transmission angle and temperature as well. Our results show that, the thermal energy transmission is highly anisotropic while thermal energy reflection is almost isotropic. In addition, we found that it seems there is a global critical angle of transmission beyond which almost no thermal energy is transmitted. This can be used to device high pass phonon filter via changing the orientation of the interface.
Calculation of the radiative properties of photosynthetic microorganisms
NASA Astrophysics Data System (ADS)
Dauchet, Jérémi; Blanco, Stéphane; Cornet, Jean-François; Fournier, Richard
2015-08-01
A generic methodological chain for the predictive calculation of the light-scattering and absorption properties of photosynthetic microorganisms within the visible spectrum is presented here. This methodology has been developed in order to provide the radiative properties needed for the analysis of radiative transfer within photobioreactor processes, with a view to enable their optimization for large-scale sustainable production of chemicals for energy and chemistry. It gathers an electromagnetic model of light-particle interaction along with detailed and validated protocols for the determination of input parameters: morphological and structural characteristics of the studied microorganisms as well as their photosynthetic-pigment content. The microorganisms are described as homogeneous equivalent-particles whose shape and size distribution is characterized by image analysis. The imaginary part of their refractive index is obtained thanks to a new and quite extended database of the in vivo absorption spectra of photosynthetic pigments (that is made available to the reader). The real part of the refractive index is then calculated by using the singly subtractive Kramers-Krönig approximation, for which the anchor point is determined with the Bruggeman mixing rule, based on the volume fraction of the microorganism internal-structures and their refractive indices (extracted from a database). Afterwards, the radiative properties are estimated using the Schiff approximation for spheroidal or cylindrical particles, as a first step toward the description of the complexity and diversity of the shapes encountered within the microbial world. Finally, these predictive results are confronted to experimental normal-hemispherical transmittance spectra for validation. This entire procedure is implemented for Rhodospirillum rubrum, Arthrospira platensis and Chlamydomonas reinhardtii, each representative of the main three kinds of photosynthetic microorganisms, i.e. respectively
OligoCalc: an online oligonucleotide properties calculator
Kibbe, Warren A.
2007-01-01
We developed OligoCalc as a web-accessible, client-based computational engine for reporting DNA and RNA single-stranded and double-stranded properties, including molecular weight, solution concentration, melting temperature, estimated absorbance coefficients, inter-molecular self-complementarity estimation and intra-molecular hairpin loop formation. OligoCalc has a familiar ‘calculator’ look and feel, making it readily understandable and usable. OligoCalc incorporates three common methods for calculating oligonucleotide-melting temperatures, including a nearest-neighbor thermodynamic model for melting temperature. Since it first came online in 1997, there have been more than 900 000 accesses of OligoCalc from nearly 200 000 distinct hosts, excluding search engines. OligoCalc is available at http://basic.northwestern.edu/biotools/OligoCalc.html, with links to the full source code, usage patterns and statistics at that link as well. PMID:17452344
Thermal properties of {sup 4}He surfaces and interfaces
Clements, B.E.; Krotscheck, E. |; Tymczak, C.J.
1997-05-01
A first-principle quantum statistical mechanical theory is used to study the properties of thick liquid {sup 4}He films absorbed to the weakly binding substrates: Li, Na, and Cs. Values for the liquid-gas and solid-liquid surface energies are determined. By fitting, at long wavelengths, the film`s lowest energy mode with the standard expression for the ripplon energy, which depends on the liquid-gas surface energy, the authors obtain excellent agreement with the liquid-vacuum surface energy from recent experiments and also the one previously extracted from quantum liquid droplet calculations. The full spectrum of excitations for wave vectors less than 0.50 {Angstrom}{sup {minus}1} is calculated using a dynamical correlated basis function theory developed in earlier work, which includes multi-phonon scattering processes. Particle currents and transition densities are used to elucidate the nature of the excitations. At a coverage of 0.40 {Angstrom}{sup {minus}2}, the lowest mode shows no significant substrate dependence, and is recognized as being a ripplon propagating in the liquid film at the liquid-gas surface. A new effect is observed for the Cs substrate; the second lowest mode is qualitatively different than found on the other substrates and is identified as interfacial ripplon. In the other substrates the second mode is a volume mode altered somewhat by the high density inner liquid layers. The linewidths of these modes are also calculated. The dynamic excitations provide the input for the thermodynamic theory and the effects on the free energy, heat capacity, and thermal surface broadening of these films are studied as function of the nature of the excitations, the number of modes, and variations in the substrate potentials.
Thermal properties of composite materials: a complex systems approximation
NASA Astrophysics Data System (ADS)
Carrillo, J. L.; Bonilla, Beatriz; Reyes, J. J.; Dossetti, Victor
We propose an effective media approximation to describe the thermal diffusivity of composite samples made of polyester resin and magnetite inclusions. By means of photoacoustic spectroscopy, the thermal diffusivity of the samples were experimentally measured. The volume fraction of the inclusions was systematically varied in order to study the changes in the effective thermal diffusivity of the composites. For some samples, a static magnetic field was applied during the polymerization process, resulting in anisotropic inclusion distributions. Our results show a significant difference in the thermal properties of the anisotropic samples, compared to the isotropic randomly distributed. We correlate some measures of the complexity of the inclusion structure with the observed thermal response through a multifractal analysis. In this way, we are able to describe, and at some extent predict, the behavior of the thermal diffusivity in terms of the lacunarity and other measures of the complexity of these samples Partial Financial Support by CONACyT México and VIEP-BUAP.
Thermoelectric properties of rocksalt ZnO from first-principles calculations
Alvarado, Andrew; Attapattu, Jeevake; Zhang, Yi; ...
2015-10-22
Zinc oxide (ZnO) undergoes a pressure-induced structural transition from its normal ambient-pressure wurtzite (WZ) phase to a rocksalt (RS) phase around 10 GPa. A recent experiment shows that the high-pressure RS ZnO phase can be recovered and stabilized at ambient conditions, which raises exciting prospects of expanding the range of properties of ZnO. For a fundamental understanding of the RS ZnO phase, we have performed first-principles calculations to determine its electronic, phonon, and thermodynamic properties at high (20 GPa) and ambient (0 GPa) pressure. Furthermore, we have calculated its electrical and thermal transport properties, which allow an evaluation of itsmore » thermoelectric figure of merit ZT at different temperature and doping levels. Our calculations show that the ambient-pressure RS ZnO phase can reach ZT values of 0.25 to 0.3 under both n-type and p-type doping in a large temperature range of 400 K to 800 K, which is considerably lower than the temperature range of 1400 K to 1600 K where WZ ZnO reaches similar ZT values. Lastly, these results establish RS ZnO as a promising material for thermoelectric devices designed to operate at temperatures desirable for many heat recovery applications.« less
Thermoelectric properties of rocksalt ZnO from first-principles calculations
Alvarado, Andrew; Attapattu, Jeevake; Zhang, Yi; Chen, Changfeng
2015-10-28
Zinc oxide (ZnO) undergoes a pressure-induced structural transition from its normal ambient-pressure wurtzite (WZ) phase to a rocksalt (RS) phase around 10 GPa. A recent experiment shows that the high-pressure RS ZnO phase can be recovered and stabilized at ambient conditions, which raises exciting prospects of expanding the range of properties of ZnO. For a fundamental understanding of the RS ZnO phase, we have performed first-principles calculations to determine its electronic, phonon, and thermodynamic properties at high (20 GPa) and ambient (0 GPa) pressure. Furthermore, we have calculated its electrical and thermal transport properties, which allow an evaluation of its thermoelectric figure of merit ZT at different temperature and doping levels. Our calculations show that the ambient-pressure RS ZnO phase can reach ZT values of 0.25 to 0.3 under both n-type and p-type doping in a large temperature range of 400 K to 800 K, which is considerably lower than the temperature range of 1400 K to 1600 K where WZ ZnO reaches similar ZT values. These results establish RS ZnO as a promising material for thermoelectric devices designed to operate at temperatures desirable for many heat recovery applications.
Thermoelectric properties of rocksalt ZnO from first-principles calculations
Alvarado, Andrew; Attapattu, Jeevake; Zhang, Yi; Chen, Changfeng
2015-10-22
Zinc oxide (ZnO) undergoes a pressure-induced structural transition from its normal ambient-pressure wurtzite (WZ) phase to a rocksalt (RS) phase around 10 GPa. A recent experiment shows that the high-pressure RS ZnO phase can be recovered and stabilized at ambient conditions, which raises exciting prospects of expanding the range of properties of ZnO. For a fundamental understanding of the RS ZnO phase, we have performed first-principles calculations to determine its electronic, phonon, and thermodynamic properties at high (20 GPa) and ambient (0 GPa) pressure. Furthermore, we have calculated its electrical and thermal transport properties, which allow an evaluation of its thermoelectric figure of merit ZT at different temperature and doping levels. Our calculations show that the ambient-pressure RS ZnO phase can reach ZT values of 0.25 to 0.3 under both n-type and p-type doping in a large temperature range of 400 K to 800 K, which is considerably lower than the temperature range of 1400 K to 1600 K where WZ ZnO reaches similar ZT values. Lastly, these results establish RS ZnO as a promising material for thermoelectric devices designed to operate at temperatures desirable for many heat recovery applications.
Pressure dependence of thermal transport properties
Hofmeister, Anne M.
2007-01-01
Pressure (P) derivatives of thermal conductivity (k) and thermal diffusivity (D) are important to geophysics but are difficult to measure accurately because minerals, being hard and partially transparent, likely incur systematic errors through thermal losses at interfaces and spurious radiative transfer. To evaluate accuracy, repeat experiments for olivine [(Mg0.9Fe0.1)2SiO4], quartz (SiO2), and NaCl are examined in detail: these and other data on electrical insulators are compared with theory. At ambient conditions, D is underestimated in proportion to the number of contacts. As temperature (T) increases, spurious radiative transfer more than offsets contact loss. Compression of pore space and contact losses affect pressure derivatives, but these seem independent of T. Accurate (±2%) values of D(T) at 1 atm are obtained with the contact-free, laser-flash method. Other optical techniques do not pinpoint D but provide useful pressure derivatives. Published data on ∂(lnk)/∂P at ambient conditions agree roughly with all available models, the simplest of which predicts ∂(lnk)/∂P ∼ ∂(lnKT)/∂P, where KT is the bulk modulus. However, derivatives verified by multiple measurements are reproduced accurately only by the damped harmonic oscillator model. An improved database is needed to refine this model and to confidently extrapolate these difficult measurements to geophysically relevant conditions. PMID:17299046
Effect of Moisture Content on Thermal Properties of Porous Building Materials
NASA Astrophysics Data System (ADS)
Kočí, Václav; Vejmelková, Eva; Čáchová, Monika; Koňáková, Dana; Keppert, Martin; Maděra, Jiří; Černý, Robert
2017-02-01
The thermal conductivity and specific heat capacity of characteristic types of porous building materials are determined in the whole range of moisture content from dry to fully water-saturated state. A transient pulse technique is used in the experiments, in order to avoid the influence of moisture transport on measured data. The investigated specimens include cement composites, ceramics, plasters, and thermal insulation boards. The effect of moisture-induced changes in thermal conductivity and specific heat capacity on the energy performance of selected building envelopes containing the studied materials is then analyzed using computational modeling of coupled heat and moisture transport. The results show an increased moisture content as a substantial negative factor affecting both thermal properties of materials and energy balance of envelopes, which underlines the necessity to use moisture-dependent thermal parameters of building materials in energy-related calculations.
Micromechanics of intraply hybrid composites: Elastic and thermal properties
NASA Technical Reports Server (NTRS)
Chamis, C. C.; Sinclair, J. H.
1979-01-01
Composite micromechanics are used to derive equations for predicting the elastic and thermal properties of unidirectional intraply hybrid composites. The results predicted using these equations are compared with those predicted using approximate equations based on the rule of mixtures, linear laminate theory, finite element analysis and limited experimental data. The comparisons for three different intraply hybrids indicate that all four methods predict approximately the same elastic properties and are in good agreement with measured data. The micromechanics equations and linear laminate theory predict about the same values for thermal expansion coefficients. The micromechanics equations predict through-the-thickness properties which are in good agreement with the finite element results.
Determination of thermal properties of composting bulking materials.
Ahn, H K; Sauer, T J; Richard, T L; Glanville, T D
2009-09-01
Thermal properties of compost bulking materials affect temperature and biodegradation during the composting process. Well determined thermal properties of compost feedstocks will therefore contribute to practical thermodynamic approaches. Thermal conductivity, thermal diffusivity, and volumetric heat capacity of 12 compost bulking materials were determined in this study. Thermal properties were determined at varying bulk densities (1, 1.3, 1.7, 2.5, and 5 times uncompacted bulk density), particle sizes (ground and bulk), and water contents (0, 20, 50, 80% of water holding capacity and saturated condition). For the water content at 80% of water holding capacity, saw dust, soil compost blend, beef manure, and turkey litter showed the highest thermal conductivity (K) and volumetric heat capacity (C) (K: 0.12-0.81 W/m degrees C and C: 1.36-4.08 MJ/m(3) degrees C). Silage showed medium values at the same water content (K: 0.09-0.47 W/m degrees C and C: 0.93-3.09 MJ/m(3) degrees C). Wheat straw, oat straw, soybean straw, cornstalks, alfalfa hay, and wood shavings produced the lowest K and C values (K: 0.03-0.30 W/m degrees C and C: 0.26-3.45 MJ/m(3) degrees C). Thermal conductivity and volumetric heat capacity showed a linear relationship with moisture content and bulk density, while thermal diffusivity showed a nonlinear relationship. Since the water, air, and solid materials have their own specific thermal property values, thermal properties of compost bulking materials vary with the rate of those three components by changing water content, bulk density, and particle size. The degree of saturation was used to represent the interaction between volumes of water, air, and solids under the various combinations of moisture content, bulk density, and particle size. The first order regression models developed in this paper represent the relationship between degree of saturation and volumetric heat capacity (r=0.95-0.99) and thermal conductivity (r=0.84-0.99) well. Improved
NASA Astrophysics Data System (ADS)
Kaplun, A. B.; Meshalkin, A. B.
2013-08-01
Using methods and approaches developed by the authors, a new low-parametric state equation for describing the thermal properties of normal substances is obtained that allows us to describe the thermal properties of gases, liquids, and fluids over a range of densities from the ideal gas state to the triple point, except for a critical region, with a high degree of accuracy close to that of an experiment. The caloric properties and speed of sound are calculated for argon, nitrogen, and carbon dioxide without using any caloric data except for the enthalpy of an ideal gas. It is established that the calculated values of enthalpy, heat capacity, the speed of speed of sound, etc., are in good agreement with the experimental (reliably tabulated) data.
NASA Technical Reports Server (NTRS)
Harloff, G. J.
1986-01-01
Real thermodynamic and transport properties of hydrogen, steam, the SSME mixture, and air are developed. The SSME mixture properties are needed for the analysis of the space shuttle main engine fuel turbine. The mixture conditions for the gases, except air, are presented graphically over a temperature range from 800 to 1200 K, and a pressure range from 1 to 500 atm. Air properties are given over a temperature range of 320 to 500 K, which are within the bounds of the thermodynamics programs used, in order to provide mixture data which is more easily checked (than H2/H2O). The real gas property variation of the SSME mixture is quantified. Polynomial expressions, needed for future computer analysis, for viscosity, Prandtl number, and thermal conductivity are given for the H2/H2O SSME fuel turbine mixture at a pressure of 305 atm over a range of temperatures from 950 to 1140 K. These conditions are representative of the SSME turbine operation. Performance calculations are presented for the space shuttle main engine (SSME) fuel turbine. The calculations use the air equivalent concept. Progress towards obtaining the capability to evaluate the performance of the SSME fuel turbine, with the H2/H2O mixture, is described.
Effect of Silver Nanoparticles on the Thermal Properties of Sodium Acetate Trihydrate
NASA Astrophysics Data System (ADS)
Garay-Ramírez, B.; Cruz-Orea, A.; San Martín-Martínez, E.
2015-06-01
Sodium acetate trihydrate (SAT) is used as a phase change material (PCM) because of its high latent heat of fusion. Mixtures were prepared with SAT, a blend of the polymer sodium carboxymethil cellulose (CMC) and silica gel, silver nanoparticles (AgNPs), and anhydrous sodium sulfate to form a composite-PCM (c-PCM) based on SAT; the relative proportions of CMC/silica gel in the blend and AgNP content were varied according to a central composite experimental design. The thermal properties were determined for raw SAT, CMC, , and c-PCM samples. The thermal effusivity of samples was evaluated by the inverse photopyroelectric technique. The thermal diffusivity was obtained for samples by the open photoacoustic cell technique. The thermal conductivity was calculated from the obtained and values. To assess the thermal performance of the c-PCM compared to raw SAT, samples were studied through differential scanning calorimetry which served to determine the latent heat recovery ( LHR). Properties , and LHR were analyzed by response surface methodology and compared. The SAT-based c-PCM was found to be more thermally conductive than raw SAT. The best LHR with good thermal diffusivity and thermal conductivity was identified in the region of the central composite experimental design with medium-low AgNPs and higher proportions of CMC in the polymer blend.
Crystallite Size Effect on Thermal Conductive Properties of Nonwoven Nanocellulose Sheets.
Uetani, Kojiro; Okada, Takumi; Oyama, Hideko T
2015-07-13
The thermal conductive properties, including the thermal diffusivity and resultant thermal conductivity, of nonwoven nanocellulose sheets were investigated by separately measuring the thermal diffusivity of the sheets in the in-plane and thickness directions with a periodic heating method. The cross-sectional area (or width) of the cellulose crystallites was the main determinant of the thermal conductive properties. Thus, the results strongly indicate that there is a crystallite size effect on phonon conduction within the nanocellulose sheets. The results also indicated that there is a large interfacial thermal resistance between the nanocellulose surfaces. The phonon propagation velocity (i.e., the sound velocity) within the nanocellulose sheets was estimated to be ∼800 m/s based on the relationship between the thermal diffusivities and crystallite widths. The resulting in-plane thermal conductivity of the tunicate nanocellulose sheet was calculated to be ∼2.5 W/mK, markedly higher than other plastic films available for flexible electronic devices.
Shao, Cheng; Bao, Hua
2016-01-01
The successful exfoliation of atomically-thin bismuth telluride (Bi2Te3) quintuple layer (QL) attracts tremendous research interest in this strongly anharmonic quasi-two-dimensional material. The thermal transport properties of this material are not well understood, especially the mode-wise properties and when it is coupled with a substrate. In this work, we have performed molecular dynamics simulations and normal mode analysis to study the mode-resolved thermal transport in freestanding and supported Bi2Te3 QL. The detailed mode-wise phonon properties are calculated and the accumulated thermal conductivities with respect to phonon mean free path (MFP) are constructed. It is shown that 60% of the thermal transport is contributed by phonons with MFP longer than 20 nm. Coupling with a-SiO2 substrate leads to about 60% reduction of thermal conductivity. Through varying the interfacial coupling strength and the atomic mass of substrate, we also find that phonon in Bi2Te3 QL is more strongly scattered by interfacial potential and its transport process is less affected by the dynamics of substrate. Our study provides an in-depth understanding of heat transport in Bi2Te3 QL and is helpful in further tailoring its thermal property through nanostructuring. PMID:27263656
Measurement of Thermal Properties of Saltstone
Steimke, J.L.; Fowley, M.D.
1998-05-01
Radioactive liquid effluent from the In Tank Precipitation Process is mixed with Portland cement, flyash and furnace alag to form Saltstone. The Saltstone is poured into vaults at Z Area for long term disposal. A transient heat transfer model of the Saltstone pouring process was previously written to determine whether the Saltstone temperature would exceed the Technical Specification Limit of 95 degrees C. The present work was performed to provide Saltstone density, heat capacity, heat of hydration and thermal conductivity for inclusion in the model.
NASA Astrophysics Data System (ADS)
Azam, Sikander; Khan, Saleem Ayaz; Goumri-Said, Souraya; Kanoun, Mohammed Benali
2017-01-01
We report a theoretical investigation of electronic structures, optical and thermoelectric properties of two ternary-layered chalcogenides, MnBi4S7 and FeBi4S7 , by combining the first principles density functional calculations and semi-local Boltzmann transport theory. The calculated electronic band structure have demonstrated that both compounds exhibit indirect band gaps. The optical transitions are explored via the dielectric function (real and imaginary parts) along with other related optical constants including refractive index, reflectivity, and energy loss spectrum. These chalcogenides have exhibited interesting thermoelectric properties such as Seebeck's coefficient, electrical and thermal conductivity, and power factor as function of temperatures.
Thermal calculation for a furnace with three-tiered near-wall burners
NASA Astrophysics Data System (ADS)
Vafin, D. B.; Sadykov, A. V.
2016-03-01
The paper considers using a differential method for thermal calculation of a furnace with finding the thermal and aerodynamic parameters within the radiation chamber of a tube furnace. The furnace is equipped with acoustictype burners allocated in three tiers on the lateral walls. The method implies joint numerical solution of 2D radiation transfer equations using the S 2-approximation of the discrete ordinate method, of energy equations, flow equations, k-ɛ turbulence model, and single-stage modeling of gas fuel combustion. Typical results of simulation are presented.
Thermal response properties of protective clothing fabrics
Baitinger, W.F.
1995-12-31
In the industrial workplace, it becomes increasingly incumbent upon employers to require employees to use suitable protective equipment and to wear protective apparel. When workers may be subjected to accidental radiant, flame, or electric arc heat sources, work clothing should be used that does not become involved in burning. It is axiomatic that work clothing should not become a primary fuel source, adding to the level of heat exposure, since clothing is usually in intimate contact with the skin. Further, clothing should provide sufficient insulation to protect the skin from severe burn injury. If the worker receives such protection from clothing, action then may be taken to escape the confronted thermal hazard. Published laboratory test methods are used to measure flame resistance and thermal responses of flame resistant fabrics in protective clothing. The purpose of this article is to review these test methods, to discuss certain limitations in application, and to suggest how flame resistant cotton fabrics may be used to enhance worker safety.
Anharmonic properties in M g2X (X =C ,Si ,Ge ,Sn ,Pb ) from first-principles calculations
NASA Astrophysics Data System (ADS)
Chernatynskiy, Aleksandr; Phillpot, Simon R.
2015-08-01
Thermal conductivity reduction is one of the potential routes to improve the performance of thermoelectric materials. However, detailed understanding of the thermal transport of many promising materials is still missing. In this paper, we employ electronic-structure calculations at the level of density functional theory to elucidate thermal transport properties of the M g2X (X =C , Si, Ge, Sn, and Pb) family of compounds, which includes M g2Si , a material already identified as a potential thermoelectric. All these materials crystallize into the same antifluorite structure. Systematic trends in the anharmonic properties of these materials are presented and examined. Our calculations indicate that the reduction in the group velocity is the main driver of the thermal conductivity trend in these materials, as the phonon lifetimes in these compounds are very similar. We also examine the limits of the applicability of perturbation theory to study the effect of point defects on thermal transport and find that it is in good agreement with experiment in a wide range of scattering parameter values. The thermal conductivity of the recently synthesized M g2C is computed and predicted to be 34 W/mK at 300 °C.
Atomic, Crystal, Elastic, Thermal, Nuclear, and Other Properties of Beryllium
Goldberg, A
2006-02-01
This report is part of a series of documents that provide a background to those involved in the construction of beryllium components and their applications. This report is divided into five sub-sections: Atomic/Crystal Structure, Elastic Properties, Thermal Properties, Nuclear Properties, and Miscellaneous Properties. In searching through different sources for the various properties to be included in this report, inconsistencies were at times observed between these sources. In such cases, the values reported by the Handbook of Chemistry and Physics was usually used. In equations, except where indicated otherwise, temperature (T) is in degrees Kelvin.
Negative thermal expansion properties in tetragonal NbPO5 from the first principles studies
NASA Astrophysics Data System (ADS)
Li, Tao; Fu, Xiaonan; Chang, Dahu; Sun, Qiang; Wang, Fei
2017-03-01
By using the first-principles calculations based on density functional theory combined with quasi-harmonic approximation, we have studied the geometric structural, thermal properties, and the negative thermal expansion (NTE) properties of tetrahedral NbPO5. The variations of cell parameter and cell volume of tetrahedral NbPO5 with temperature show that it displays NTE behavior in the range of 473-800 K along a-axis and the corresponding average coefficient of thermal expansion (CTE) is approximately -0.766 ×10-6 K-1, while the c cell parameter and the cell volume display positive thermal expansion behaviors. These results are in consistent well with the experiment observations. Further vibrational modes analysis, together with Grüneisen parameters calculations, revealed that the transverse vibration of O corner atoms accompanying the rocking motions of corner-shared NbO6 octahedron and PO4 tetrahedron dominate the negative thermal properties of tetrahedral NbPO5. Our findings will provide an understanding for the underlying mechanisms of the NTE in oxides materials.
First-principles calculations of the thermal stability of Ti 3SiC 2(0001) surfaces
NASA Astrophysics Data System (ADS)
Orellana, Walter; Gutiérrez, Gonzalo
2011-12-01
The energetic, thermal stability and dynamical properties of the ternary layered ceramic Ti3SiC2(0001) surface are addressed by density-functional theory calculations and molecular dynamic (MD) simulations. The equilibrium surface energy at 0 K of all terminations is contrasted with thermal stability at high temperatures, which are investigated by ab initio MD simulations in the range of 800 to 1400 °C. We find that the toplayer (sublayer) surface configurations: Si(Ti2) and Ti2(Si) show the lowest surface energies with reconstruction features for Si(Ti2). However, at high temperatures they are unstable, forming disordered structures. On the contrary, Ti1(C) and Ti2(C) despite their higher surface energies, show a remarkable thermal stability at high temperatures preserving the crystalline structures up to 1400 °C. The less stable surfaces are those terminated in C atoms, C(Ti1) and C(Ti2), which at high temperatures show surface dissociation forming amorphous TiCx structures. Two possible atomic scale mechanisms involved in the thermal stability of Ti3SiC2(0001) are discussed.
Thermal properties of dielectric solids below 4 K. I - Polycarbonate
NASA Technical Reports Server (NTRS)
Cieloszyk, G. S.; Cruz, M. T.; Salinger, G. L.
1973-01-01
Polymers and other dielectric materials are frequently used for many purposes in the construction of cryogenic apparatus. Yet very few values of the thermal properties of these materials below 4 K have been reported. It is, however, known that one can not use the Debye theory to extrapolate to lower temperatures the measurements of the specific heat capacity above 1 K. The thermal conductivity also follows no theoretically predictable temperature dependence. As a by-product of our studies of the thermal properties of amorphous and partly crystalline materials below 4 K, we wish to report values for the thermal conductivity, specific heat capacity, and velocity of sound below 4 K in materials useful for the construction of cryogenic apparatus. In this article we will describe our measurement techniques and report values for polycarbonate (Lexan). In subsequent notes we will give values for other materials of interest.
High pressure elasticity and thermal properties of depleted uranium
NASA Astrophysics Data System (ADS)
Jacobsen, M. K.; Velisavljevic, N.
2016-04-01
Studies of the phase diagram of uranium have revealed a wealth of high pressure and temperature phases. Under ambient conditions the crystal structure is well defined up to 100 gigapascals (GPa), but very little information on thermal conduction or elasticity is available over this same range. This work has applied ultrasonic interferometry to determine the elasticity, mechanical, and thermal properties of depleted uranium to 4.5 GPa. Results show general strengthening with applied load, including an overall increase in acoustic thermal conductivity. Further implications are discussed within. This work presents the first high pressure studies of the elasticity and thermal properties of depleted uranium metal and the first real-world application of a previously developed containment system for making such measurements.
Thermal properties of the martian surface inferred from OMEGA data
NASA Astrophysics Data System (ADS)
Audouard, J.; Poulet, F.; Vincendon, M.; Bibring, J.; Gondet, B.; Langevin, Y.
2011-12-01
Martian surface temperatures are the results of radiative exchanges between the air and the shallow subsurface. Thermal inertia (TI) and the albedo are key parameters for modulating diurnal temperature variation of surfaces. TI, which represents the resistance to change in temperature of the upper few centimeters of the subsurface throughout the day, is independent of local time, latitude, and season. Thermal infrared spectrometers TES and THEMIS that measured the surface temperature have been frequently used to derive the thermal properties of the martian surface (see e.g. Putzig et al. 2005; Fergason et al. 2006). Global TI derivation techniques usually assume that the thermophysical properties of the soil are vertically uniform (Putzig et al. 2005), while vertical heterogeneities are observed (Putzig and Mellon 2007; Bandfield and Feldman 2008). As the thermal wave penetration depth varies with season, various apparent thermal inertias are derived as a function of season for a given location (Putzig et al. 2005). Surface temperatures (larger than ~200 K) can be derived from the OMEGA/Mars Express hyperspectral observations (Jouglet et al. 2007). Of special interest is the elliptical MEX orbit that makes possible to observe a given surface element at various local time and solar longitude. This allow us to explore different parts of the thermal response of martian soils and can be used to better constrain the properties of the subsurface. We have developed an operational pixel-to-pixel climate modeling interface using the Martian Global Climate Model (Forget et al. 1999), in order to compare the surface temperature measured by OMEGA with the modeled temperature. A systematic comparison data/model covering 4 Martian years will be discussed. A few local scale thermal inertia retrievals will be then presented and compared to previous studies based on TES/MGS and THEMIS/Mars Odyssey data. We will also investigate the thermophysical properties of soils where anomalous
Thermal property of insulation material for HTS power cable
NASA Astrophysics Data System (ADS)
Choi, Yeon Suk; Kim, D. L.; Shin, D. W.; Hwang, S. D.
2012-06-01
The thermal property of insulation material is essential in developing a high temperature superconductor (HTS) power cable operating at around liquid nitrogen temperature. The accurate estimate of the heat flux is difficult in the nonmetallic materials because nonmetallic materials have a high thermal resistance and low temperature gradient along the specimen. The objective of the present work is to develop a precise instrument for measuring the thermal conductivity of insulating materials over a temperature range of 30 K to approximately the room temperature by using a cryocooler. The thermal conductivity of Teflon is measured and the accuracy confirmation is carried out by comparing published data. In addition, the experimental results of apparent thermal conductivity of polypropylene laminated paper (PPLP) are presented and the temperature dependency is also discussed
Thermal properties of continuously spun carbon nanotube fibres
NASA Astrophysics Data System (ADS)
Koziol, Krzysztof K.; Janas, Dawid; Brown, Elisabetta; Hao, Ling
2017-04-01
As indicated by theory and experimental measurements individual carbon nanotubes (CNTs) have very high values of thermal conductivity. One of the challenges is to achieve high thermal conductivity in macroscopic assemblies of CNTs such as fibres, films and composites, paving the way to a wide range of applications. CNT fibres have tremendous potential in succeeding as the future materials for a variety of applications when properties at the nanoscale are translated to their macroscopic assemblies. In this paper we report the measurements of thermal conductivity of continuously spun CNT fibres and its dependence on temperature. Thermal conductivity measurements were performed using in-house built temperature sensing microscope probe. Specific thermal conductivity of CNT fibres showed an order of magnitude advantage over the traditional materials used for heat dissipation.
Antioxidant Properties of Kynurenines: Density Functional Theory Calculations
2016-01-01
Kynurenines, the main products of tryptophan catabolism, possess both prooxidant and anioxidant effects. Having multiple neuroactive properties, kynurenines are implicated in the development of neurological and cognitive disorders, such as Alzheimer's, Parkinson's, and Huntington's diseases. Autoxidation of 3-hydroxykynurenine (3HOK) and its derivatives, 3-hydroxyanthranilic acid (3HAA) and xanthommatin (XAN), leads to the hyperproduction of reactive oxygen species (ROS) which damage cell structures. At the same time, 3HOK and 3HAA have been shown to be powerful ROS scavengers. Their ability to quench free radicals is believed to result from the presence of the aromatic hydroxyl group which is able to easily abstract an electron and H-atom. In this study, the redox properties for kynurenines and several natural and synthetic antioxidants have been calculated at different levels of density functional theory in the gas phase and water solution. Hydroxyl bond dissociation enthalpy (BDE) and ionization potential (IP) for 3HOK and 3HAA appear to be lower than for xanthurenic acid (XAA), several phenolic antioxidants, and ascorbic acid. BDE and IP for the compounds with aromatic hydroxyl group are lower than for their precursors without hydroxyl group. The reaction rate for H donation to *O-atom of phenoxyl radical (Ph-O*) and methyl peroxy radical (Met-OO*) decreases in the following rankings: 3HOK ~ 3HAA > XAAOXO > XAAENOL. The enthalpy absolute value for Met-OO* addition to the aromatic ring of the antioxidant radical increases in the following rankings: 3HAA* < 3HOK* < XAAOXO* < XAAENOL*. Thus, the high free radical scavenging activity of 3HAA and 3HOK can be explained by the easiness of H-atom abstraction and transfer to O-atom of the free radical, rather than by Met-OO* addition to the kynurenine radical. PMID:27861556
"TPSX: Thermal Protection System Expert and Material Property Database"
NASA Technical Reports Server (NTRS)
Squire, Thomas H.; Milos, Frank S.; Rasky, Daniel J. (Technical Monitor)
1997-01-01
The Thermal Protection Branch at NASA Ames Research Center has developed a computer program for storing, organizing, and accessing information about thermal protection materials. The program, called Thermal Protection Systems Expert and Material Property Database, or TPSX, is available for the Microsoft Windows operating system. An "on-line" version is also accessible on the World Wide Web. TPSX is designed to be a high-quality source for TPS material properties presented in a convenient, easily accessible form for use by engineers and researchers in the field of high-speed vehicle design. Data can be displayed and printed in several formats. An information window displays a brief description of the material with properties at standard pressure and temperature. A spread sheet window displays complete, detailed property information. Properties which are a function of temperature and/or pressure can be displayed as graphs. In any display the data can be converted from English to SI units with the click of a button. Two material databases included with TPSX are: 1) materials used and/or developed by the Thermal Protection Branch at NASA Ames Research Center, and 2) a database compiled by NASA Johnson Space Center 9JSC). The Ames database contains over 60 advanced TPS materials including flexible blankets, rigid ceramic tiles, and ultra-high temperature ceramics. The JSC database contains over 130 insulative and structural materials. The Ames database is periodically updated and expanded as required to include newly developed materials and material property refinements.
Atomistic calculation of the thermal conductance of large scale bulk-nanowire junctions
Duchemin, Ivan; Donadio, Davide
2011-09-15
We have developed a stable and efficient kernel method to compute thermal transport in open systems, based on the scattering-matrix approach. This method is applied to compute the thermal conductance of a junction between bulk silicon and silicon nanowires with diameter up to 10 nm. We have found that beyond a threshold diameter of 7 nm, transmission spectra and contact conductances scale with the cross section of the contact surface, whereas deviations from this general trend are observed in thinner wires. This result allows us to predict the thermal resistance of bulk-nanowire interfaces with larger cross sections than those tractable with atomistic simulations, and indicate the characteristic size beyond which atomistic systems can in principle be treated accurately by mean-field theories. Our calculations also elucidate how dimensionality reduction and shape affect interfacial heat transport.
The anomalous thermal properties of glasses at low temperatures
NASA Technical Reports Server (NTRS)
Pohl, R. O.; Salinger, G. L.
1976-01-01
While experimentally there is great regularity below 1 deg K in the behavior of a particular thermal property for all amorphous dielectrics it is not understood why these properties should differ from those of crystalline dielectrics, since it would seem that at low temperatures long-wavelength elastic waves, similar in both cases, would determine the thermal properties. A model involving systems having very few levels is used in the present study, although the relation between the model's systems and the nature of the glassy state is not known. It is shown, among other effects, that: specific heat measurements above 0.1 K indicate a distribution of local modes independent of energy; ultrasonic velocity measurements give information about phonon-local mode coupling parameters; and thermal expansion and far infrared experiments indicate a phonon-assisted tunneling model.
Scattering, Thermal Emission and Extinction: Column Density and Dust Properties
NASA Astrophysics Data System (ADS)
Foster, Jonathan
2013-07-01
We compare three different ways to measure the column density of molecular clouds using (1) scat- tered light (cloudshine), (2) thermal emission in the sub-millimeter and (3) extinction of background stars. Our methods for estimating the column density from thermal emission and from extinction of background stars use hierarchical Bayesian models to coherently infer correlations in the dust properties and the column density estimates. In particular, we measure the slope of the extinction law (Rv) from extinction estimates and the deviation from blackbody emission (beta) from the thermal emission estimates. These dust properties are related to the size distribution and compo- sition of dust. The comparison among these three methods therefore tells us about which regimes particular methods work or fail and about the properties of the dust at different depths inside the cloud.
1972-01-01
34Validity of the Drude Theory for Silver, Gold, and Aluminum in the Infrared," from Optical Properties and Electronic Structure of Metals and Alloys (F...Comprehensive Compilation of Data by the Thermophysical Properties Research Center (TPRC), Purdue University Y. 8. Touloukian , Series Editor C. Y. Ho, Series...Volume 6. Specific Heat-Nonmetallic Liquids and Gases Volume 7. Thermal Radiative Properties -Metallic Elements and Alloys Volume 8. Thermal Radiative
Calculation of momentum distribution function of a non-thermal fermionic dark matter
NASA Astrophysics Data System (ADS)
Biswas, Anirban; Gupta, Aritra
2017-03-01
The most widely studied scenario in dark matter phenomenology is the thermal WIMP scenario. Inspite of numerous efforts to detect WIMP, till now we have no direct evidence for it. A possible explanation for this non-observation of dark matter could be because of its very feeble interaction strength and hence, failing to thermalise with the rest of the cosmic soup. In other words, the dark matter might be of non-thermal origin where the relic density is obtained by the so-called freeze-in mechanism. Furthermore, if this non-thermal dark matter is itself produced substantially from the decay of another non-thermal mother particle, then their distribution functions may differ in both size and shape from the usual equilibrium distribution function. In this work, we have studied such a non-thermal (fermionic) dark matter scenario in the light of a new type of U(1)B‑L model. The U(1)B‑L model is interesting, since, besides being anomaly free, it can give rise to neutrino mass by Type II see-saw mechanism. Moreover, as we will show, it can accommodate a non-thermal fermionic dark matter as well. Starting from the collision terms, we have calculated the momentum distribution function for the dark matter by solving a coupled system of Boltzmann equations. We then used it to calculate the final relic abundance, as well as other relevant physical quantities. We have also compared our result with that obtained from solving the usual Boltzmann (or rate) equations directly in terms of comoving number density, Y. Our findings suggest that the latter approximation is valid only in cases where the system under study is close to equilibrium, and hence should be used with caution.
Montan, D.N.; Patrick, W.C.
1981-09-30
The Spent Fuel Test-Climax (SFT-C) is a test of retrievable deep geologic storage of commercially generated spent nuclear reactor fuel in granitic rock. Eleven spent fuel assemblies, together with six electrical simulators and 20 guard heaters, are emplaced 420 m below the surface in the Climax granite at the US Department of Energy Nevada Test Site. On June 2, 1978 LLNL secured funding for the SFT-C, and completed spent fuel emplacement May 28, 1980. This report documents a series of thermal calculations that were performed in support of the SFT-C. Early calculations employed analytical solutions to address such design and construction issues as drift layout and emplacement hole spacings. Operational aspects of the test required more detailed numerical solutions dealing with ventilation and guard-heater power levels. The final set of calculations presented here provides temperature histories throughout the test facility for evaluation of the response of the SFT-C and for comparison of calculations with acquired data. This final set of calculations employs the as-built test geometry and best-available material properties.
Direct calculation of thermal emission for three-dimensionally periodic photonic crystal slabs.
Chan, David L C; Soljacić, Marin; Joannopoulos, J D
2006-09-01
We perform direct thermal emission calculations for three-dimensionally periodic photonic crystal slabs using stochastic electrodynamics following the Langevin approach, implemented via a finite-difference time-domain algorithm. We demonstrate that emissivity and absorptivity are equal, by showing that such photonic crystal systems emit as much radiation as they absorb, for every frequency, up to statistical fluctuations. We also study the effect of surface termination on absorption and emission spectra from these systems.
Direct calculation of thermal emission for three-dimensionally periodic photonic crystal slabs
NASA Astrophysics Data System (ADS)
Chan, David L. C.; Soljačić, Marin; Joannopoulos, J. D.
2006-09-01
We perform direct thermal emission calculations for three-dimensionally periodic photonic crystal slabs using stochastic electrodynamics following the Langevin approach, implemented via a finite-difference time-domain algorithm. We demonstrate that emissivity and absorptivity are equal, by showing that such photonic crystal systems emit as much radiation as they absorb, for every frequency, up to statistical fluctuations. We also study the effect of surface termination on absorption and emission spectra from these systems.
Accurate calculated optical properties of substituted quaterphenylene nanofibers.
Finnerty, Justin J; Koch, Rainer
2010-01-14
The accurate prediction of both excitation and emission energies of substituted p-quaterphenylenes using a variety of established and newly developed density functional methods is evaluated and compared against experimental data, both from single molecules and from nanofibers. For calculation of the UV-vis excitation the MPW1K functional is the best performing method (with the employed TZVP basis set). After a linear scaling factor is applied, mPW2-PLYP, CIS and the very fast INDO/S also reproduce the experimental data correctly. For the fluorescence relaxation energies MPW1K, mPW2-PLYP, and INDO/S give good results, even without scaling. However, mPW2-PLYP involves second-order perturbation to introduce nonlocal electron correlation and therefore requires significantly more resources, so the recommended level of theory for a single methodology to investigate the optical properties of substituted phenylenes and related systems is MPW1K/6-311+G(2d,p), followed by INDO/S as a low-cost alternative. As an extension of a previous work on predicting first hyperpolarisabilities, we can now demonstrate that the chosen approach (HF/6-31G(d)//B3LYP/6-31G(d)) produces data that correlate well with the susceptibilities derived from measurements on nanofibers.
An assessment of the CORCON-MOD3 code. Part 1: Thermal-hydraulic calculations
Strizhov, V.; Kanukova, V.; Vinogradova, T.; Askenov, E.; Nikulshin, V.
1996-09-01
This report deals with the subject of CORCON-Mod3 code validation (thermal-hydraulic modeling capability only) based on MCCI (molten core concrete interaction) experiments conducted under different programs in the past decade. Thermal-hydraulic calculations (i.e., concrete ablation, melt temperature, melt energy, concrete temperature, and condensible and non-condensible gas generation) were performed with the code, and compared with the data from 15 experiments, conducted at different scales using both simulant (metallic and oxidic) and prototypic melt materials, using different concrete types, and with and without an overlying water pool. Sensitivity studies were performed in a few cases involving, for example, heat transfer from melt to concrete, condensed phase chemistry, etc. Further, special analysis was performed using the ACE L8 experimental data to illustrate the differences between the experimental and the reactor conditions, and to demonstrate that with proper corrections made to the code, the calculated results were in better agreement with the experimental data. Generally, in the case of dry cavity and metallic melts, CORCON-Mod3 thermal-hydraulic calculations were in good agreement with the test data. For oxidic melts in a dry cavity, uncertainties in heat transfer models played an important role for two melt configurations--a stratified geometry with segregated metal and oxide layers, and a heterogeneous mixture. Some discrepancies in the gas release data were noted in a few cases.
A thermodynamic model of thermal end elastic properties of curium
NASA Astrophysics Data System (ADS)
Povzner, A. A.; Filanovich, A. N.; Oskina, V. A.
2013-11-01
A self-consistent thermodynamic model of curium is developed. In the framework of this model the temperature dependencies of heat capacity, coefficient of thermal expansion, bulk modulus and Debye temperature of Cm are calculated. It is shown that the phonon anharmonicity of Cm is weaker than in the case of Np and δ-Pu, but stronger than in lanthanides.
Phonon thermal properties of graphene from molecular dynamics using different potentials
NASA Astrophysics Data System (ADS)
Zou, Ji-Hang; Ye, Zhen-Qiang; Cao, Bing-Yang
2016-10-01
Phonon thermal transport in graphene has attracted significant interest in recent years. Phonon thermal properties of graphene are investigated by molecular dynamics simulations using the Tersoff, Tersoff-2010, REBO, and AIREBO potentials. By calculating the phonon properties and thermal conductivity of graphene, the performance of the potentials is evaluated based on comparisons with experimental data. It shows that the Tersoff-2010 and REBO display better dispersion curves for graphene than the original Tersoff and AIREBO. The Tersoff-2010 correctly provides the Γ point phonon velocities of the LA and TA branches as well as the G peak frequency with a value of 46 THz. In addition, the acoustic phonon relaxation time derived from the Tersoff-2010 satisfies the ideal relation "τ-1 ∝ ν2." It is also found that the Tersoff-2010 provides the highest graphene thermal conductivity among the used potentials, and estimates about 30.0% contribution for flexural phonons to the total thermal conductivity. By comparison, the Tersoff-2010 potential is demonstrated to be the most suitable one to describe the phonon thermal properties of graphene.
NASA Astrophysics Data System (ADS)
Guo, San-Dong; Wang, Yue-Hua
2017-01-01
Two-dimensional (2D) materials may have potential applications in thermoelectric devices. In this work, the thermoelectric properties of orthorhombic group IV-VI monolayers AB (A = Ge and Sn; B = S and Se) are systematically investigated by the first-principles calculations and semiclassical Boltzmann transport theory. The spin-orbit coupling (SOC) is considered for their electron part, which produces observable effects on the power factor, especially for n-type doping. According to the calculated ZT, the four monolayers exhibit diverse anisotropic thermoelectric properties although they have a similar hinge-like crystal structure. The GeS along zigzag and armchair directions shows the strongest anisotropy, while SnS and SnSe show mostly isotropic efficiency of thermoelectric conversion. This can be explained by the strength of anisotropy of their respective power factor and electronic and lattice thermal conductivities. The calculated results show that the ZT between n- and p-type doping has little difference for GeS, SnS, and SnSe. It is found that GeSe, SnS, and SnSe show better thermoelectric performance compared to GeS in n-type doping and that SnS and SnSe exhibit higher efficiency of thermoelectric conversion in p-type doping. Compared to other many 2D materials, orthorhombic group IV-VI monolayers AB (A = Ge and Sn; B = S and Se) may possess better thermoelectric performance due to lower lattice thermal conductivities. Our work would be beneficial to stimulate further theoretical and experimental works.
Tian, Xiaojuan; Itkis, Mikhail E.; Bekyarova, Elena B.; Haddon, Robert C.
2013-01-01
Thermal interface materials (TIMs) are crucial components of high density electronics and the high thermal conductivity of graphite makes this material an attractive candidate for such applications. We report an investigation of the in-plane and through-plane electrical and thermal conductivities of thin thermal interface layers of graphite nanoplatelet (GNP) based composites. The in-plane electrical conductivity exceeds its through-plane counterpart by three orders of magnitude, whereas the ratio of the thermal conductivities is about 5. Scanning electron microscopy reveals that the anisotropy in the transport properties is due to the in-plane alignment of the GNPs which occurs during the formation of the thermal interface layer. Because the alignment in the thermal interface layer suppresses the through-plane component of the thermal conductivity, the anisotropy strongly degrades the performance of GNP-based composites in the geometry required for typical thermal management applications and must be taken into account in the development of GNP-based TIMs.
NASA Astrophysics Data System (ADS)
Diascorn, N.; Sallee, H.; Calas, S.; Rigacci, A.; Achard, P.
2015-07-01
Organic aerogels based on polyurethane were elaborated via sol-gel synthesis and dried with supercritical carbon dioxide (CO2). The influence of the catalyst concentration was investigated, first in order to decrease the reaction kinetics, then to study its impact on the obtained materials properties. It was shown that this parameter also influences the global shrinkage and the bulk density of the resulting materials. Its effect on the dry materials was studied in terms of morphological, textural and thermal properties in order to determine the main correlations thanks to scanning electron microscopy (SEM), nitrogen adsorption, non-intrusive mercury porosimetry and thermal conductivity measurements. Results allowed us to demonstrate a correlation between the bulk density, the texture and the thermal conductivity of this family of polyurethane aerogels and to determine an optimal density range for thermal performance associated with a fine internal mesoporous texture.
Thermal property measurement of insulating material used in HTS power device
NASA Astrophysics Data System (ADS)
Choi, Yeon Suk; Kim, Dong Lak
2012-10-01
An experiment to measure the thermal property of insulating material at cryogenic temperature has been performed. The main objective of this study is to develop a precise instrument for measuring the thermal property of insulating materials over a temperature range of 30 K to approximately room temperature by utilizing a cryocooler. In a vacuum chamber, the cold head of the cryocooler is thermally anchored to the copper link and used to bring the apparatus to a desired temperature. An electric heater is placed in the middle of test sample for generating uniform heat flux. The entire apparatus is covered by thermal shields and wrapped in multi-layer insulation to minimize thermal radiation in a vacuum chamber. For a supplied heat flux the temperature distribution in test sample, polypropylene laminated paper (PPLP), is measured in steady state, from which the effective thermal conductivity is calculated and presented with respect to the mean temperature. The correlation near liquid nitrogen temperature is derived from measured data. Moreover, using the measured thermal conductivity, we obtain the specific heat of PPLP by solving one-dimensional heat diffusion equation.
Fatigue properties of shuttle thermal protection system
NASA Technical Reports Server (NTRS)
Sawyer, J. W.; Cooper, P. A.
1980-01-01
Static and cyclic load tests were conducted to determine the static and fatigue strength of the RIS tile/SIP thermal protection system used on the orbiter of the space shuttle. The material systems investigated include the densified and undensified LI-900 tile system on the .40 cm thick SIP and the densified and undensified LI-2200 tile system on the .23 cm (.090 inch) thick SIP. The tests were conducted at room temperature with a fully reversed uniform cyclic loading at 1 Hertz. Cyclic loading causes a relatively large reduction in the stress level that each of the SIP/tile systems can withstand for a small number of cycles. For example, the average static strength of the .40 cm thick SIP/LI-900 tile system is reduced from 86 kPa to 62 kPa for a thousand cycles. Although the .23 cm thick SIP/LI-2200 tile system has a higher static strength, similar reductions in the fatigue strength are noted. Densifying the faying surface of the RSI tile changes the failure mode from the SIP/tile interface to the parent RSI or the SIP and thus greatly increases the static strength of the system. Fatigue failure for the densified tile system, however, occurs due to complete separation or excessive elongation of the SIP and the fatigue strength is only slightly greater than that for the undensified tile system.
A short history of nomograms and tables used for thermal radiation calculations
NASA Astrophysics Data System (ADS)
Stewart, Seán. M.; Johnson, R. Barry
2016-09-01
The theoretical concept of a perfect thermal radiator, the blackbody, was first introduced by the German physicist Gustav Robert Kirchhoff in 1860. By the latter half of the nineteenth century it had become the object of intense theoretical and experimental investigation. While an attempt at trying to theoretically understand the behavior of radiation emitted from a blackbody was undertaken by many eminent physicists of the day, its solution was not found until 1900 when Max Planck put forward his now famous law for thermal radiation. Today, of course, understanding blackbody behavior is vitally important to many fields including infrared systems, illumination, pyrometry, spectroscopy, astronomy, thermal engineering, cryogenics, and meteorology. Mathematically, the form Planck's law takes is rather cumbersome meaning calculations made with it before the advent of modern computers were rather tedious, dramatically slowing the process of computation. Fortunately, during those early days of the twentieth century researchers quickly realized Planck's equation, and the various functions closely related to it, readily lend themselves to being given a graphical, mechanical, or numerically tabulated form for their evaluation. The first of these computational aids to appear were tables. These arose shortly after Planck introduced his equation, were produced in the greatest number, and remained unsurpassed in their level of accuracy compared to all other aids made. It was also not long before nomograms designed to aid thermal radiation calculations appeared. Essentially a printed chart and requiring nothing more than a straightedge to use, nomograms were cheap and extremely easy to use. Facilitating instant answers to a range of quantities relating to thermal radiation, a number were produced and the inventiveness displayed in some was quite remarkable. In this paper we consider the historical development of many of the nomograms and tables developed and used by generations
Review on thermal properties of nanofluids: Recent developments.
Angayarkanni, S A; Philip, John
2015-11-01
Nanofluids are dispersions of nanomaterials (e.g. nanoparticles, nanofibers, nanotubes, nanowires, nanorods, nanosheet, or droplets) in base fluids. Nanofluids have been a topic of great interest during the last one decade primarily due to the initial reports of anomalous thermal conductivity (k) enhancement in nanofluids with a small percentage of nanoparticles. This field has been quite controversial, with multiple reports of anomalous enhancement in thermal conductivity and many other reports of the thermal conductivity increase within the classical Maxwell mixing model. Several mechanisms have been proposed for explaining the observed enhancement in thermal conductivity. The role of Brownian motion, interfacial resistance, morphology of suspended nanoparticles and aggregating behavior is investigated both experimentally and theoretically. As the understanding of specific heat capacity of nanofluids is a prerequisite for their effective utilization in heat transfer applications, it is also investigated by many researchers. From the initial focus on thermophysical properties of nanofluids, the attention is now shifted to tailoring of novel nanofluids with large thermal conductivities. Further, to overcome the limitations of traditional heat transfer media, phase change materials (PCMs) and hybrid nanofluids are being developed as effective media for thermal energy storage. This review focuses the recent progress in nanofluids research from a heat transfer perspective. Emphasis is given for the latest work on thermal properties of nanofluids, phase change materials and hybrid nanofluids. The preparation of nanofluids by various techniques, methods of stabilization, stability measurement techniques, thermal conductivity and heat capacity studies, proposed mechanisms of heat transport, theoretical models on thermal conductivity, factors influencing k and the effect of nanoinclusions in PCM are discussed in this review. Sufficient background information is also
Thermal Properties of Lunar Regolith Simulants
NASA Technical Reports Server (NTRS)
Street, Kenneth W., Jr.; Ray, Chandra; Rickman, Doug; Scheiman, Daniel A.
2010-01-01
Various high temperature chemical processes have been developed to extract oxygen and metals from lunar regolith. These processes are tested using terrestrial analogues of the regolith. But all practical terrestrial analogs contain H2O and/or OH-, the presence of which has substantial impact on important system behaviors. We have undertaken studies of lunar regolith simulants to determine the limits of the simulants to validate key components for human survivability during sustained presence on the Moon. Differential Thermal Analysis (DTA) yields information on phase transitions and melting temperatures. Thermo-Gravimetric Analysis (TGA) with Fourier Transform Infrared (FTIR) analysis provides information on evolved gas species and their evolution temperature profiles. The DTA and TGA studies included JSC-1A fine (Johnson Space Center Mare Type 1A simulant), NU-LHT-2M (National Aeronautics and Space Administration (NASA)-- United States Geological Survey (USGS)--Lunar Highlands Type 2M simulant) and its proposed feedstocks: anorthosite; dunite; high quality (HQ) glass and the norite from which HQ glass is produced. As an example, the DTA and TGA profiles for anorthosite follow. The DTA indicates exothermic transitions at 355 and 490 C and endothermic transitions at 970 and 1235 C. Below the 355 C transition, water is lost accounting for approximately 0.1 percent mass loss. Just above 490 C a second type of water is lost, presumably bound in lattices of secondary minerals along with other volatile oxides. Limited TGA-FTIR data is available at the time of this writing. For JSC-1A fine, the TGA-FTIR indicates at least two kinds of water are evolved in the 100 to 500 and the 700 to 900 C ranges. Evolution of carbon dioxide types occurs in the 250 to 545, 545 to 705, and 705 to 985 C ranges. Geologically, the results are consistent with the evolution of "water" in its several forms, CO2 from break down of secondary carbonates and magmatic, dissolved gas and glass
Thermal properties of soils: effect of biochar application
NASA Astrophysics Data System (ADS)
Usowicz, Boguslaw; Lukowski, Mateusz; Lipiec, Jerzy
2014-05-01
Thermal properties (thermal conductivity, heat capacity and thermal diffusivity) have a significant effect on the soil surface energy partitioning and resulting in the temperature distribution. Thermal properties of soil depend on water content, bulk density and organic matter content. An important source of organic matter is biochar. Biochar as a material is defined as: "charcoal for application as a soil conditioner". Biochar is generally associated with co-produced end products of pyrolysis. Many different materials are used as biomass feedstock for biochar, including wood, crop residues and manures. Additional predictions were done for terra preta soil (also known as "Amazonian dark earth"), high in charcoal content, due to adding a mixture of charcoal, bone, and manure for thousands of years i.e. approximately 10-1,000 times longer than residence times of most soil organic matter. The effect of biochar obtained from the wood biomass and other organic amendments (peat, compost) on soil thermal properties is presented in this paper. The results were compared with wetland soils of different organic matter content. The measurements of the thermal properties at various water contents were performed after incubation, under laboratory conditions using KD2Pro, Decagon Devices. The measured data were compared with predictions made using Usowicz statistical-physical model (Usowicz et al., 2006) for biochar, mineral soil and soil with addition of biochar at various water contents and bulk densities. The model operates statistically by probability of occurrence of contacts between particular fractional compounds. It combines physical properties, specific to particular compounds, into one apparent conductance specific to the mixture. The results revealed that addition of the biochar and other organic amendments into the soil caused considerable reduction of the thermal conductivity and diffusivity. The mineral soil showed the highest thermal conductivity and diffusivity
NASA Astrophysics Data System (ADS)
Schindler, Stefan; Mergheim, Julia; Zimmermann, Marco; Aurich, Jan C.; Steinmann, Paul
2017-01-01
A two-scale material modeling approach is adopted in order to determine macroscopic thermal and elastic constitutive laws and the respective parameters for metal matrix composite (MMC). Since the common homogenization framework violates the thermodynamical consistency for non-constant temperature fields, i.e., the dissipation is not conserved through the scale transition, the respective error is calculated numerically in order to prove the applicability of the homogenization method. The thermomechanical homogenization is applied to compute the macroscopic mass density, thermal expansion, elasticity, heat capacity and thermal conductivity for two specific MMCs, i.e., aluminum alloy Al2024 reinforced with 17 or 30 % silicon carbide particles. The temperature dependency of the material properties has been considered in the range from 0 to 500°C, the melting temperature of the alloy. The numerically determined material properties are validated with experimental data from the literature as far as possible.
Structural, electronic and thermal properties of Mo{sub 3}Ir superconductors
Subhashree, G. Sankar, S.; Krithiga, R.; Devi, L. Vimala
2015-06-24
Self consistent first principle calculations on superconducting material Mo{sub 3}Ir of A15 phase have been performed to understand their fundamental characteristics of the structural, electronic and thermal properties. The bulk modulus (B{sub 0}), Debye temperature (θ{sub D}), density of states (N (E{sub F})) and electronic specific heat coefficient (γ) have been computed in terms of the electronic structure results obtained by using the tight-binding linear muffin tin orbital (TB-LMTO) method based on the density functional theory (DFT) within the local density approximation (LDA). Structural, electronic and thermal properties calculated here are found to corroborate well with the experimental and theoretical results of literature.
Thermal and thermomechanical properties of poly(butylene succinate) nanocomposites.
Makhatha, Mamookho E; Ray, Suprakas Sinha; Hato, Joseph; Luyt, Adriaan S
2008-04-01
This article describes the thermal and thermomechanical properties of poly(butylene succinate) (PBS) and its nanocomposites. PBS nanocomposites with three different weight ratios of organically modified synthetic fluorine mica (OMSFM) have been prepared by melt-mixing in a batch mixer at 140 degrees C. The structure and morphology of the nanocomposites were characterized by X-ray diffraction (XRD) analyses and transmission electron microscopy (TEM) observations that reveal the homogeneous dispersion of the intercalated silicate layers into the PBS matrix. The thermal properties of pure PBS and the nanocomposite samples were studied by both conventional and temperature modulated differential scanning calorimetry (DSC) analyses, which show multiple melting behavior of the PBS matrix. The investigation of the thermomechanical properties was performed by dynamic mechanical analysis. Results reveal significant improvement in the storage modulus of neat PBS upon addition of OMSFM. The tensile modulus of neat PBS is also increased substantially with the addition of OMSFM, however, the strength at yield and elongation at break of neat PBS systematically decreases with the loading of OMSFM. The thermal stability of the nanocomposites compared to that of the pure polymer sample was examined under both pyrolytic and thermo-oxidative environments. It is shown that the thermal stability of PBS is increased moderately in the presence of 3 wt% of OMSFM, but there is no significant effect on further silicate loading in the oxidative environment. In the nitrogen environment, however, the thermal stability systematically decreases with increasing clay loading.
Thermal Properties of Lunar Regolith Simulants
NASA Technical Reports Server (NTRS)
Street, Kenneth; Ray, Chandra; Rickman, Doug
2010-01-01
Various high temperature chemical processes have been developed to extract oxygen and metals from lunar regolith. These processes are tested using terrestrial analogues of the regolith. But all practical terrestrial analogs contain H2O and/or OH-, the presence of which has substantial impact on important system behaviors. We have undertaken studies of lunar regolith simulants to determine the limits of the simulants to validate key components for human survivability during sustained presence on the moon. Differential Thermal Analysis (DTA) yields information on phase transitions and melting temperatures. Themo-Gravimetric Analysis (TGA) with mass spectrometric (MS) determination of evolved gas species yields chemical information on various oxygenated volatiles (water, carbon dioxide, sulfur oxides, nitrogen oxides and phosphorus oxides) and their evolution temperature profiles. The DTA and TGAMS studies included JSC-1A fine, NU-LHT-2M and its proposed feed stocks: anorthosite; dunite; HQ (high quality) glass and the norite from which HQ glass is produced. Fig 1 is a data profile for anorthosite. The DTA (Fig 1a) indicates exothermic transitions at 355 and 490 C and endothermic transitions at 970 and 1235 C. Below the 355 C transition, water (Molecular Weight, MW, 18 in Fig 1c) is lost accounting for approximately 0.1% mass loss due to water removal (Fig 1b). Just above 490 C a second type of water is lost, presumably bound in lattices of secondary minerals. Between 490 and the 970 transition other volatile oxides are lost including those of hydrogen (third water type), carbon (MW = 44), sulfur (MW = 64 and 80), nitrogen (MW 30 and 46) and possibly phosphorus (MW = 79, 95 or 142). Peaks at MW = 35 and 19 may be attributable to loss of chlorine and fluorine respectively. Negative peaks in the NO (MW = 30) and oxygen (MW = 32) MS profiles may indicate the production of NO2 (MW = 46). Because so many compounds are volatilized in this temperature range quantification of
Thermal Properties of Lunar Regolith Simulants
NASA Technical Reports Server (NTRS)
Street, Kenneth; Ray, Chandra; Rickman, Doug
2010-01-01
Various high temperature chemical processes have been developed to extract oxygen and metals from lunar regolith. These processes are tested using terrestrial analogues of the regolith. But all practical terrestrial analogs contain H2O and/or OH(-), the presence of which has substantial impact on important system behaviors. We have undertaken studies of lunar regolith simulants to determine the limits of the simulants to validate key components for human survivability during sustained presence on the moon. Differential Thermal Analysis (DTA) yields information on phase transitions and melting temperatures. Themo-Gravimetric Analysis (TGA) with mass spectrometric (MS) determination of evolved gas species yields chemical information on various oxygenated volatiles (water, carbon dioxide, sulfur oxides, nitrogen oxides and phosphorus oxides) and their evolution temperature profiles. The DTA and TGAMS studies included JSC-1A fine, NU-LHT-2M and its proposed feed stocks: anorthosite; dunite; HQ (high quality) glass and the norite from which HQ glass is produced. Fig 1 is a data profile for anorthosite. The DTA (Fig 1a) indicates exothermic transitions at 355 and 490 C and endothermic transitions at 970 and 1235 C. Below the 355 C transition, water (Molecular Weight, MW, 18 in Fig 1c) is lost accounting for approximately 0.1% mass loss due to water removal (Fig 1b). Just above 490 C a second type of water is lost, presumably bound in lattices of secondary minerals. Between 490 and the 970 transition other volatile oxides are lost including those of hydrogen (third water type), carbon (MW = 44), sulfur (MW = 64 and 80), nitrogen (MW 30 and 46) and possibly phosphorus (MW = 79, 95 or 142). Peaks at MW = 35 and 19 may be attributable to loss of chlorine and fluorine respectively. Negative peaks in the NO (MW = 30) and oxygen (MW = 32) MS profiles may indicate the production of NO2 (MW = 46). Because so many compounds are volatilized in this temperature range quantification
2D calculations of the thermal effects due to femtosecond laser-metal interaction
NASA Astrophysics Data System (ADS)
Valette, S.; Le Harzic, R.; Huot, N.; Audouard, E.; Fortunier, R.
2005-07-01
Experimental results previously published have shown that the radial heat affected zone (HAZ) for a 500 nm thick Al sample in the femtosecond case is less than 2 μm [Appl. Phys. Lett. 80 (2002) 3886]. The spread of radial thermal effects for femtosecond pulses is calculated, by developing a two-dimensional version of the two temperature model (TTM). The case of an axi-symmetrical geometry is simulated by a finite element technique. A physical metallurgy approach is used to define and to estimate the radial HAZ width from the calculations. The evolution of the temperature as a function of time is studied, leading to a radial HAZ width of 220 nm for 500 nm thick Al samples. Similar calculations in the nanosecond regime are also performed and compared to the femtosecond case.
Temperature-dependent thermal properties of ex vivo liver undergoing thermal ablation.
Guntur, Sitaramanjaneya Reddy; Lee, Kang Il; Paeng, Dong-Guk; Coleman, Andrew John; Choi, Min Joo
2013-10-01
Thermotherapy uses a heat source that raises temperatures in the target tissue, and the temperature rise depends on the thermal properties of the tissue. Little is known about the temperature-dependent thermal properties of tissue, which prevents us from accurately predicting the temperature distribution of the target tissue undergoing thermotherapy. The present study reports the key thermal parameters (specific heat capacity, thermal conductivity and heat diffusivity) measured in ex vivo porcine liver while being heated from 20 ° C to 90 ° C and then naturally cooled down to 20 ° C. The study indicates that as the tissue was heated, all the thermal parameters resulted in plots with asymmetric quasi-parabolic curves with temperature, being convex downward with their minima at the turning temperature of 35-40 ° C. The largest change was observed for thermal conductivity, which decreased by 9.6% from its initial value (at 20 ° C) at the turning temperature (35 ° C) and rose by 45% at 90 ° C from its minimum (at 35 ° C). The minima were 3.567 mJ/(m(3) ∙ K) for specific heat capacity, 0.520 W/(m.K) for thermal conductivity and 0.141 mm(2)/s for thermal diffusivity. The minimum at the turning temperature was unique, and it is suggested that it be taken as a characteristic value of the thermal parameter of the tissue. On the other hand, the thermal parameters were insensitive to temperature and remained almost unchanged when the tissue cooled down, indicating that their variations with temperature were irreversible. The rate of the irreversible rise at 35 ° C was 18% in specific heat capacity, 40% in thermal conductivity and 38.3% in thermal diffusivity. The study indicates that the key thermal parameters of ex vivo porcine liver vary largely with temperature when heated, as described by asymmetric quasi-parabolic curves of the thermal parameters with temperature, and therefore, substantial influence on the temperature distribution of the tissue undergoing
TOPAZ2D heat transfer code users manual and thermal property data base
Shapiro, A.B.; Edwards, A.L.
1990-05-01
TOPAZ2D is a two dimensional implicit finite element computer code for heat transfer analysis. This user's manual provides information on the structure of a TOPAZ2D input file. Also included is a material thermal property data base. This manual is supplemented with The TOPAZ2D Theoretical Manual and the TOPAZ2D Verification Manual. TOPAZ2D has been implemented on the CRAY, SUN, and VAX computers. TOPAZ2D can be used to solve for the steady state or transient temperature field on two dimensional planar or axisymmetric geometries. Material properties may be temperature dependent and either isotropic or orthotropic. A variety of time and temperature dependent boundary conditions can be specified including temperature, flux, convection, and radiation. Time or temperature dependent internal heat generation can be defined locally be element or globally by material. TOPAZ2D can solve problems of diffuse and specular band radiation in an enclosure coupled with conduction in material surrounding the enclosure. Additional features include thermally controlled reactive chemical mixtures, thermal contact resistance across an interface, bulk fluid flow, phase change, and energy balances. Thermal stresses can be calculated using the solid mechanics code NIKE2D which reads the temperature state data calculated by TOPAZ2D. A three dimensional version of the code, TOPAZ3D is available. The material thermal property data base, Chapter 4, included in this manual was originally published in 1969 by Art Edwards for use with his TRUMP finite difference heat transfer code. The format of the data has been altered to be compatible with TOPAZ2D. Bob Bailey is responsible for adding the high explosive thermal property data.
Effect of Amorphisation on the Thermal Properties of Nanostructured Membranes
NASA Astrophysics Data System (ADS)
Termentzidis, Konstantinos; Verdier, Maxime; Lacroix, David
2017-02-01
The majority of the silicon devices contain amorphous phase and amorphous/crystalline interfaces which both considerably affect the transport of energy carriers as phonons and electrons. In this article, we investigate the impact of amorphous phases (both amorphous silicon and amorphous SiO2) of silicon nanoporous membranes on their thermal properties via molecular dynamics simulations. We show that a small fraction of amorphous phase reduces dramatically the thermal transport. One can even create nanostructured materials with subamorphous thermal conductivity, while keeping an important crystalline fraction. In general, the a-SiO2 shell around the pores reduces the thermal conductivity by a factor of five to ten compared to a-Si shell. The phonon density of states for several systems is also given to give the impact of the amorphisation on the phonon modes.
Investigation of thermal conductivity and tribological properties of nanofluids
NASA Astrophysics Data System (ADS)
Gara, Luan
Nanofluids are engineered by dispersing and stably suspending nanoparticles with typical length on the order of 1--50 nm in traditional fluids. In the past decade, scientists and engineers have made great progresses in finding that a very small amount (< 1 vol %) of dispersed nanoparticles can provide dramatic improvement in the thermal properties of the base fluids. Therefore, numerous mechanisms and models have been proposed to account for the thermal enhancement of nanofluids. The molecular dynamics (MD) simulation has become an important tool in the study of dynamic properties of liquids, molecular solutions, and macromolecules. Therefore, MD simulation is a very helpful tool to model the enhanced thermal conduction and predict thermal conductivities of nanofluids. In recent years, investigations on the tribological properties of nanofluids have also been carried out. Some papers have reported that nanofluids are effective in reducing wear and friction. The mechanisms of friction reduction and anti-wear of nanoparticles in lubricants have been reported as colloidal effect, rolling effect, protective film, and third body. The objective of this research is to study the thermal conductivity and tribological properties of nanofluids. The thermal conductivity of nanofluids was investigated theoretically through MD simulation. Nanodiamond was selected as the nanoparticle and octane as the base oil. The Large-scale Atomic-Molecular Massively Parallel Simulator (LAMMPS) was used. The effects of the particle size, shape and concentration on the thermal conductivity of nanofluids was investigated. The thermal conductivity of oil based nanofluids with nanodiamond particles was also measured experimentally using transient hot-wire method. The tribological properties of nanofluids were studied through experimental investigation using commercially available nanopowders and nanofluids. Both water based and oil based nanofluids were investigated. A Universal Micro
Experimental determination of thermal properties of alluvial soil
NASA Astrophysics Data System (ADS)
Kulkarni, N. G.; Bhandarkar, U. V.; Puranik, B. P.; Rao, A. B.
2016-12-01
In the present work, thermal conductivity and specific heat of a particular type of alluvial soil used in brick making in a certain region of India (Karad, Maharashtra State) are experimentally determined for later use in the estimation of ground heat loss in clamp type kilns. These properties are determined simultaneously using the steady-state and the transient temperature data measured in the setup constructed for this purpose. Additionally, physical properties of the soil are experimentally determined for use with six models for the prediction of the thermal conductivity of soil. The predictions from the models are compared with the experimental data. A separate data fitting exercise revealed a small temperature dependence of the soil thermal conductivity on the soil mean temperature.
Densification and Thermal Properties of Zirconium Diboride Based Ceramics
2012-01-01
density as a function of time of attrition milled ZrB2 during spark plasma sintering to a final temperature of 1900°C...as a function of temperature during hot pressing (A) and spark plasma sintering (B) of ZrB2...effects of densification method ( sintering , hot pressing, or spark plasma sintering ) on the microstructure, mechanical, and thermal properties were
Oats Protein Isolate: Thermal, Rheological, Surface & Functional Properties
Technology Transfer Automated Retrieval System (TEKTRAN)
Oat protein isolate (OPI) was extracted in 0.015 N NaOH in a 10:1 ratio solvent:flour and was precipitated by adjusting the pH to 4.5 and freeze-dried. The thermal properties of OPI were determined using Differential Scanning Calorimetry (DSC). OPI with 6% moisture content exhibited a glass transi...
Phase diagram and thermal properties of strong-interaction matter
NASA Astrophysics Data System (ADS)
Gao, Fei; Chen, Jing; Liu, Yu-Xin; Qin, Si-Xue; Roberts, Craig D.; Schmidt, Sebastian M.
2016-05-01
We introduce a novel method for computing the (μ , T )-dependent pressure in continuum QCD, from which we obtain a complex phase diagram and predictions for thermal properties of the dressed-quark component of the system, providing the in-medium behavior of the related trace anomaly, speed of sound, latent heat, and heat capacity.
Thermal treatment and mechanical properties of aluminum-2021
NASA Technical Reports Server (NTRS)
Brennecke, M. W.
1970-01-01
Mechanical properties, after thermal treatments, are summarized for sheet and plate of copper-rich, high-strength, heat-treatable aluminum-2021. The alloy is quench sensitive, quench rate and variations in aging affect corrosion behavior. Aging effects on yield strength, tensile strength, and elongation of sheet and plate are compared.
Phase diagram and thermal properties of strong-interaction matter
Gao, Fei; Chen, Jing; Liu, Yu-Xin; Qin, Si-Xue; Roberts, Craig D.; Schmidt, Sebastian M.
2016-05-20
We introduce a novel method for computing the (μ, T)-dependent pressure in continuum QCD, from which we obtain a complex phase diagram and predictions for thermal properties of the dressed-quark component of the system, providing the in-medium behavior of the related trace anomaly, speed of sound, latent heat, and heat capacity.
NASA Astrophysics Data System (ADS)
Holmes, Jesse Curtis
Nuclear data libraries provide fundamental reaction information required by nuclear system simulation codes. The inclusion of data covariances in these libraries allows the user to assess uncertainties in system response parameters as a function of uncertainties in the nuclear data. Formats and procedures are currently established for representing covariances for various types of reaction data in ENDF libraries. This covariance data is typically generated utilizing experimental measurements and empirical models, consistent with the method of parent data production. However, ENDF File 7 thermal neutron scattering library data is, by convention, produced theoretically through fundamental scattering physics model calculations. Currently, there is no published covariance data for ENDF File 7 thermal libraries. Furthermore, no accepted methodology exists for quantifying or representing uncertainty information associated with this thermal library data. The quality of thermal neutron inelastic scattering cross section data can be of high importance in reactor analysis and criticality safety applications. These cross sections depend on the material's structure and dynamics. The double-differential scattering law, S(alpha, beta), tabulated in ENDF File 7 libraries contains this information. For crystalline solids, S(alpha, beta) is primarily a function of the material's phonon density of states (DOS). Published ENDF File 7 libraries are commonly produced by calculation and processing codes, such as the LEAPR module of NJOY, which utilize the phonon DOS as the fundamental input for inelastic scattering calculations to directly output an S(alpha, beta) matrix. To determine covariances for the S(alpha, beta) data generated by this process, information about uncertainties in the DOS is required. The phonon DOS may be viewed as a probability density function of atomic vibrational energy states that exist in a material. Probable variation in the shape of this spectrum may be
Calculation of thermal inertia from day-night measurements separated by days or weeks
NASA Technical Reports Server (NTRS)
Kahle, A. B.; Alley, R. E.
1985-01-01
The calculation of the thermal inertia of an area from remotely sensed data involves the measurement of the surface albedo and the determination of the diurnal temperature range of the surface in image format. The temperature-range image is calculated from surface thermal radiance measured as near as possible to the time of maximum surface temperature and (predawn) surface minimum temperature. Ordinarily, both surface-temperature images are measured within the same 12-hour period. If this is impossible, then the measurement of the predawn surface radiance within a 36-hour period has been considered to be adequate, although less satisfactory. The problems arising in connection with the impossibility to conduct measurements within the same 12-hour period are studied, and suggestions are made for cases in which only relative thermal inertia across an area is required. In such cases investigators should consider using the best day-night temperature pairs available, even if not acquired within a 12 to 36 hour period.
Thermal transport in van der Waals solids from first-principles calculations
NASA Astrophysics Data System (ADS)
Lindroth, Daniel O.; Erhart, Paul
2016-09-01
The lattice thermal expansion and conductivity in bulk Mo and W-based transition metal dichalcogenides are investigated by means of density functional and Boltzmann transport theory calculations. To this end, a recent van der Waals density functional (vdW-DF-CX) is employed, which is shown to yield excellent agreement with reference data for the structural parameters. The calculated in-plane thermal conductivity compares well with experimental room-temperature values, when phonon-phonon and isotopic scattering are included. To explain the behavior over the entire available temperature range one must, however, include additional (temperature independent) scattering mechanisms that limit the mean free path. Generally, the primary heat carrying modes have mean free paths of 1 μ m or more, which makes these materials very susceptible to structural defects. The conductivity of Mo- and W-based transition metal dichalcogenides is primarily determined by the chalcogenide species and increases in the order Te-Se-S. While for the tellurides and selenides the transition metal element has a negligible effect, the conductivity of WS2 is notably higher than for MoS2, which may be traced to the much larger phonon band gap of the former. Overall, the present study provides a consistent set of thermal conductivities that reveal chemical trends and constitute the basis for future investigations of van der Waals solids.
Foldable dome climate measurements and thermal properties
NASA Astrophysics Data System (ADS)
Sliepen, Guus; Jägers, Aswin P. L.; Hammerschlag, Robert H.; Bettonvil, Felix C. M.
2010-07-01
As part of a larger project for measuring various aspects of foldable domes in the context of EST and with support of the Dutch Technology Foundation STW, we have collected over a year of continuous temperature and humidity measurements, both inside and outside the domes of the Dutch Open Telescope (DOT) on La Palma5 and the GREGOR telescope on Tenerife.6 In addition, we have measured the wind field around each dome. Although the structure of both domes is similar, the DOT dome has a single layer of cloth, and is situated on top of an open tower. In contrast, the GREGOR dome has a double layer of cloth, and is situated on top of a tower-shaped building. These differences result in large differences in temperature and humidity insulation when the dome is closed. We will present the changes in temperature and humidity one can expect for each dome within one day, and the statistics for the variations throughout a year. In addition, we will show that the main advantage of a foldable dome is the near instantaneous equilibration of the air inside the volume originally enclosed by the dome and that of the environment outside the dome. This property allows one to operate a telescope without needing expensive air conditioning and dome skin temperature control in order to limit dome and shell seeing effects. The measurements give also information about the weather fluctuations at the sites of the domes. It was observed that on small time scales the temperature fluctuations are significantly greater during the day than during the night.
Ab initio calculation of the thermodynamic properties of InSb under intense laser irradiation
Feng, ShiQuan; Cheng, XinLu; Zhao, JianLing; Zhang, Hong
2013-07-28
In this paper, phonon spectra of InSb at different electronic temperatures are presented. Based on the phonon dispersion relationship, we further perform a theoretical investigation of the thermodynamic properties of InSb under intense laser irradiation. The phonon entropy, phonon heat capacity, and phonon contribution to Helmholtz free energy and internal energy of InSb are calculated as functions of temperature at different electronic temperatures. The abrupt change in the phonon entropy- temperature curve from T{sub e} = 0.75 to 1.0 eV provides an indication of InSb undergoing a phase transition from solid to liquid. It can be considered as a collateral evidence of non-thermal melting for InSb under intense electronic excitation effect.
NASA Astrophysics Data System (ADS)
Huang, Feng; Jiang, Nan; Wang, Yuefeng; Dong, Wei; Niu, Yanxiong
2008-03-01
Laser diode (LD) pumped slab laser, as an important high average power solid-state laser, is a promising laser source in military and industrial fields. The different laser diode pumping structures lead to different thermal effect in the slab gain medium. The thermal and stress analysis of slab laser with different pumping structure are performed by finite element analysis (FEA) with the software program ANSYS. The calculation results show that the face pumped and cooled laser results in a near one-dimension temperature distribution and eliminates thermal stress induced depolarization. But the structure is low pump efficiency due to the small thickness of slabs and the requirement to cool and pump through the same faces. End-pumped slab laser is high pump efficiency and excellent mode match, but its pumping arrangement is fairly complicated. The edge-pumped face-cooling slab laser's pump efficiency is better than face-pumping, and its pumping structure is simpler than end-pumped laser, but the tensile stress on surfaces may initiate failure of the gain medium so it is important to design so that the stress is well below the stress fracture limit. The comparison of the thermal effects with different pumping structure shows that, the edge-pumped slab laser has engineering advantages in high power slab laser's application. Furthermore, the end-pumped slab laser tends to get the best beam quality, so it is fit for the application which has a special requirement on laser beam quality.
Thermal properties measurement of dry bulk materials with a cylindrical three layers device
NASA Astrophysics Data System (ADS)
Jannot, Y.; Degiovanni, A.
2013-09-01
This paper presents a new method dedicated to thermal properties (conductivity and diffusivity) measurement of dry bulk materials including powders. The cylindrical three layers experimental device (brass/bulk material/stainless steel) and the principle of the measurement method based on a crenel thermal excitation are presented. The one-dimensional modeling of the system is used for a sensitivity analysis and to calculate the standard deviation of the estimation error. Experimental measurements are carried out on three bulk materials: glass beads, cork granules, and expanded polystyrene beads. The estimated thermal properties are compared with the values obtained by other measurement methods. Results are in good agreement with theoretical predictions: both thermal conductivity and diffusivity can be estimated with a good accuracy for low density material like cork granules or expanded polystyrene beads since only thermal diffusivity can be estimated for heavier materials like glass beads. It is finally shown that this method like all transient methods is not suited to the thermal characterization of wet bulk materials.
Thermal Properties of Oxides With Magnetoplumbite Structure for Advanced Thermal Barrier Coatings
NASA Technical Reports Server (NTRS)
Bansal, Narottam P.; Zhu, Dongming; Eslamloo-Grami, Maryam
2007-01-01
Oxides having magnetoplumbite structure are promising candidate materials for applications as high temperature thermal barrier coatings because of their high thermal stability, high thermal expansion, and low thermal conductivity. In this study, powders of LaMgAl11O19, GdMgAl11O19, SmMgAl11O19, and Gd0.7Yb0.3MgAl11O19 magnetoplumbite oxides were synthesized by citric acid sol-gel method and hot pressed into disk specimens. The thermal expansion coefficients (CTE) of these oxide materials were measured from room temperature to 1500 C. The average CTE value was found to be approx.9.6x10(exp -6)/C. Thermal conductivity of these magnetoplumbite-based oxide materials was also evaluated using steady-state laser heat flux test method. The effects of doping on thermal properties were also examined. Thermal conductivity of the doped Gd0.7Yb0.3MgAl11O19 composition was found to be lower than that of the undoped GdMgAl11O19. In contrast, thermal expansion coefficient was found to be independent of the oxide composition and appears to be controlled by the magnetoplumbite crystal structure. Thermal conductivity testing of LaMgAl11O19 and LaMnAl11O19 magnetoplumbite oxide coatings plasma sprayed on NiCrAlY/Rene N5 superalloy substrates indicated resistance of these coatings to sintering even at temperatures as high as 1600 C.
NASA Astrophysics Data System (ADS)
Cartoixà, Xavier; Dettori, Riccardo; Melis, Claudio; Colombo, Luciano; Rurali, Riccardo
2016-07-01
We study thermal transport in porous Si nanowires (SiNWs) by means of approach-to-equilibrium molecular dynamics simulations. We show that the presence of pores greatly reduces the thermal conductivity, κ, of the SiNWs as long mean free path phonons are suppressed. We address explicitly the dependence of κ on different features of the pore topology—such as the porosity and the pore diameter—and on the nanowire (NW) geometry—diameter and length. We use the results of the molecular dynamics calculations to tune an effective model, which is capable of capturing the dependence of κ on porosity and NW diameter. The model illustrates the failure of Matthiessen's rule to describe the coupling between boundary and pore scattering, which we account for by the inclusion of an additional empirical term.
Mechanical And Thermal Properties Of Optical Materials - A Review
NASA Astrophysics Data System (ADS)
Ballard, Stanley S.
1980-02-01
In selecting an optical material, the instrument designer's first consideration is optical properties, especially transmission region but also homogeneity, freedom from birefringence, perhaps refractive index and dispersion. Next in his hierarchy are the other physical properties: mechanical, thermal, and chemical (solubility, for example). In this review article, the several properties are listed, and data sources are given. No single compilation or handbook contains all the desired data, so many references are quoted. This review covers materials useful in the ultraviolet and esuecially the infrared spectral regions; it does not include the standard glasses used in the visible region.
WETAIR: A computer code for calculating thermodynamic and transport properties of air-water mixtures
NASA Technical Reports Server (NTRS)
Fessler, T. E.
1979-01-01
A computer program subroutine, WETAIR, was developed to calculate the thermodynamic and transport properties of air water mixtures. It determines the thermodynamic state from assigned values of temperature and density, pressure and density, temperature and pressure, pressure and entropy, or pressure and enthalpy. The WETAIR calculates the properties of dry air and water (steam) by interpolating to obtain values from property tables. Then it uses simple mixing laws to calculate the properties of air water mixtures. Properties of mixtures with water contents below 40 percent (by mass) can be calculated at temperatures from 273.2 to 1497 K and pressures to 450 MN/sq m. Dry air properties can be calculated at temperatures as low as 150 K. Water properties can be calculated at temperatures to 1747 K and pressures to 100 MN/sq m. The WETAIR is available in both SFTRAN and FORTRAN.
Designing energy dissipation properties via thermal spray coatings
Brake, Matthew R. W.; Hall, Aaron Christopher; Madison, Jonathan D.
2016-12-14
The coefficient of restitution is a measure of energy dissipation in a system across impact events. Often, the dissipative qualities of a pair of impacting components are neglected during the design phase. This research looks at the effect of applying a thin layer of metallic coating, using thermal spray technologies, to significantly alter the dissipative properties of a system. We studied the dissipative properties across multiple impacts in order to assess the effects of work hardening, the change in microstructure, and the change in surface topography. The results of the experiments indicate that any work hardening-like effects are likely attributable to the crushing of asperities, and the permanent changes in the dissipative properties of the system, as measured by the coefficient of restitution, are attributable to the microstructure formed by the thermal spray coating. Furthermore, the microstructure appears to be robust across impact events of moderate energy levels, exhibiting negligible changes across multiple impact events.
Thermal properties of carbon black aqueous nanofluids for solar absorption
NASA Astrophysics Data System (ADS)
Han, Dongxiao; Meng, Zhaoguo; Wu, Daxiong; Zhang, Canying; Zhu, Haitao
2011-07-01
In this article, carbon black nanofluids were prepared by dispersing the pretreated carbon black powder into distilled water. The size and morphology of the nanoparticles were explored. The photothermal properties, optical properties, rheological behaviors, and thermal conductivities of the nanofluids were also investigated. The results showed that the nanofluids of high-volume fraction had better photothermal properties. Both carbon black powder and nanofluids had good absorption in the whole wavelength ranging from 200 to 2,500 nm. The nanofluids exhibited a shear thinning behavior. The shear viscosity increased with the increasing volume fraction and decreased with the increasing temperature at the same shear rate. The thermal conductivity of carbon black nanofluids increased with the increase of volume fraction and temperature. Carbon black nanofluids had good absorption ability of solar energy and can effectively enhance the solar absorption efficiency.
Thermal properties of carbon black aqueous nanofluids for solar absorption
2011-01-01
In this article, carbon black nanofluids were prepared by dispersing the pretreated carbon black powder into distilled water. The size and morphology of the nanoparticles were explored. The photothermal properties, optical properties, rheological behaviors, and thermal conductivities of the nanofluids were also investigated. The results showed that the nanofluids of high-volume fraction had better photothermal properties. Both carbon black powder and nanofluids had good absorption in the whole wavelength ranging from 200 to 2,500 nm. The nanofluids exhibited a shear thinning behavior. The shear viscosity increased with the increasing volume fraction and decreased with the increasing temperature at the same shear rate. The thermal conductivity of carbon black nanofluids increased with the increase of volume fraction and temperature. Carbon black nanofluids had good absorption ability of solar energy and can effectively enhance the solar absorption efficiency. PMID:21767359
Thermal properties of carbon black aqueous nanofluids for solar absorption.
Han, Dongxiao; Meng, Zhaoguo; Wu, Daxiong; Zhang, Canying; Zhu, Haitao
2011-07-18
In this article, carbon black nanofluids were prepared by dispersing the pretreated carbon black powder into distilled water. The size and morphology of the nanoparticles were explored. The photothermal properties, optical properties, rheological behaviors, and thermal conductivities of the nanofluids were also investigated. The results showed that the nanofluids of high-volume fraction had better photothermal properties. Both carbon black powder and nanofluids had good absorption in the whole wavelength ranging from 200 to 2,500 nm. The nanofluids exhibited a shear thinning behavior. The shear viscosity increased with the increasing volume fraction and decreased with the increasing temperature at the same shear rate. The thermal conductivity of carbon black nanofluids increased with the increase of volume fraction and temperature. Carbon black nanofluids had good absorption ability of solar energy and can effectively enhance the solar absorption efficiency.
Electronic and Thermal Properties of Graphene and Carbon Structures
NASA Astrophysics Data System (ADS)
Anthony, Gilmore; Khatun, Mahfuza
2011-10-01
We will present the general properties of carbon structures. The research involves the study of carbon structures: Graphene, Graphene nanoribbons (GNRs), and Carbon Nanotubes (CNTs). A review of electrical and thermal conduction phenomena of the structures will be discussed. Particularly carbon nanoribbons and CNTs have many interesting physical properties, and have the potential for device applications. Our research interests include the study of electronic structures, electrical and thermal transport properties of the carbon structures. Results are produced analytically as well as by simulation. The numerical simulations are conducted using various tools such as Visual Molecular Dynamics (VMD), Large Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), NanoHub at Purdue University and the Beowulf Cluster at Ball State University.
Thermoelectric properties of AgSbTe₂ from first-principles calculations
Rezaei, Nafiseh; Akbarzadeh, Hadi; Hashemifar, S. Javad
2014-09-14
The structural, electronic, and transport properties of AgSbTe₂ are studied by using full-relativistic first-principles electronic structure calculation and semiclassical description of transport parameters. The results indicate that, within various exchange-correlation functionals, the cubic Fd3⁻m and trigonal R3⁻m structures of AgSbTe₂ are more stable than two other considered structures. The computed Seebeck coefficients at different values of the band gap and carrier concentration are accurately compared with the available experimental data to speculate a band gap of about 0.1–0.35 eV for AgSbTe₂ compound, in agreement with our calculated electronic structure within the hybrid HSE (Heyd-Scuseria-Ernzerhof) functional. By calculating the semiclassical Seebeck coefficient, electrical conductivity, and electronic part of thermal conductivity, we present the theoretical upper limit of the thermoelectric figure of merit of AgSbTe₂ as a function of temperature and carrier concentration.
NASA Astrophysics Data System (ADS)
Bohac, Vlastimil; Gustavsson, Mattias K.; Kubicar, Ludovit; Gustafsson, Silas E.
2000-06-01
The objective of this work is to improve measurements of transport properties using the hot disk thermal constants analyzer. The principle of this method is based on the transient heating of a plane double spiral sandwiched between two pieces of the investigated material. From the temperature increase of the heat source, it is possible to derive both the thermal conductivity and the thermal diffusivity from one single transient recording, provided the total time of the measurement is chosen within a correct time window defined by the theory and the experimental situation. Based on a theory of sensitivity coefficients, it is demonstrated how the experimental time window should be selected under different experimental situations. In addition to the theoretical work, measurements on two different materials: poly(methylmethacrylate) and Stainless Steel A 310, with thermal conductivity of 0.2 and 14 W/mK, respectively, have been performed and analyzed based on the developed theory.
Thermophysical and Thermomechanical Properties of Thermal Barrier Coating Systems
NASA Technical Reports Server (NTRS)
Zhu, Dongming; Miller, Robert A.
2000-01-01
Thermal barrier coatings have been developed for advanced gas turbine and diesel engine applications to improve engine reliability and fuel efficiency. However, the issue of coating durability under high temperature cyclic conditions is still of major concern. The coating failure is closely related to thermal stresses and oxidation in the coating systems. Coating shrinkage cracking resulting from ceramic sintering and creep at high temperatures can further accelerate the coating failure process. The purpose of this paper is to address critical issues such as ceramic sintering and creep, thermal fatigue and their relevance to coating life prediction. Novel test approaches have been established to obtain critical thermophysical and thermomechanical properties of the coating systems under near-realistic temperature and stress gradients encountered in advanced engine systems. Emphasis is placed on the dynamic changes of the coating thermal conductivity and elastic modulus, fatigue and creep interactions, and resulting failure mechanisms during the simulated engine tests. Detailed experimental and modeling results describing processes occurring in the thermal barrier coating systems provide a framework for developing strategies to manage ceramic coating architecture, microstructure and properties.
Optical characterization of thermal properties of biological tissue
NASA Astrophysics Data System (ADS)
Gutierrez-Arroyo, A.; Sánchez Pérez, C.; Alemán-García, N.; Piña-Barba, C.
2013-11-01
In this work we utilize heat conduction measurements trough the photothermal beam deflection technique to characterize thermal properties of biological tissue. We design a heat flux sensor based on the phenomenon of photothermal laser beam deflection within a thermo-optic slab (acrylic), where the deflection is quantified by an optical fiber angle sensor. We analytically model the heat flux sensor response based on heat wave propagation theory that well agree with experimental data. We present heat conduction measurements on different tissues applying a heat pulse. Hence we obtain the thermal effusivity coefficient of bovine tendon and chicken liver and heart. It has been shown that thermal conduction depends on the tissués chemical composition as well on their structural arrangements, so any modification in tissue will affect on heat conduction rendering this method potentially useful as an auxiliary in biomedical studies. Nowadays there are several thermal effusivity and diffusivity measurement techniques with classic calorimetry (using thermistors) for research and industrial applications. However there are only few integrated optical devices already proposed, turning this optical technique in an innovative and alternative sensing system for thermal properties characterization.
Characterization of thermal properties of municipal solid waste landfills.
Faitli, József; Magyar, Tamás; Erdélyi, Attila; Murányi, Attila
2015-02-01
Municipal waste landfills represent not only a source of landfill gases, but a source of thermal energy as well. The heat in landfills is generated by physical, chemical and microbiological processes. The goal of our study was to characterize the thermal properties of municipal solid waste (MSW) samples of the given landfill. A new apparatus was designed and constructed to measure heat flow. A systematic test series of 17 discrete measurements was carried out with municipal waste samples of 1.0-1.7 m(3). The thermal conductivity, heat diffusivity and specific heat capacity of the samples were determined. Analysing the results of the sampling and our experiments it was realized that the theoretical fundaments should be clarified. Two theories were developed for the serial and for the parallel heat flow in three phase disperse systems. The serial and parallel models resulted in different theoretical estimations. The measured thermal conductivity and heat diffusivity were better characterized by the parallel heat flow estimations. The results show that heat can flow parallel in solid, liquid and gas phases. Characterization of thermal properties serves to establish the fundament of heat extraction from municipal waste landfills.
Fabrication, characterization, and thermal property evaluation of silver nanofluids
NASA Astrophysics Data System (ADS)
Noroozi, Monir; Radiman, Shahidan; Zakaria, Azmi; Soltaninejad, Sepideh
2014-11-01
Silver nanoparticles were successfully prepared in two different solvents using a microwave heating technique, with various irradiation times. The silver nanoparticles were dispersed in polar liquids (distilled water and ethylene glycol) without any other reducing agent, in the presence of the stabilizer polyvinylpyrrolidone (PVP). The optical properties, thermal properties, and morphology of the synthesized silver particles were characterized using ultraviolet-visible spectroscopy, photopyroelectric technique, and transmission electron microscopy. It was found that for the both solvents, the effect of microwave irradiation was mainly on the particles distribution, rather than the size, which enabled to make stable and homogeneous silver nanofluids. The individual spherical nanostructure of self-assembled nanoparticles has been formed during microwave irradiation. Ethylene glycol solution, due to its special properties, such as high dielectric loss, high molecular weight, and high boiling point, can serve as a good solvent for microwave heating and is found to be a more suitable medium than the distilled water. A photopyroelectric technique was carried out to measure thermal diffusivity of the samples. The precision and accuracy of this technique was established by comparing the measured thermal diffusivity of the distilled water and ethylene glycol with values reported in the literature. The thermal diffusivity ratio of the silver nanofluids increased up to 1.15 and 1.25 for distilled water and ethylene glycol, respectively.
Fabrication, characterization, and thermal property evaluation of silver nanofluids.
Noroozi, Monir; Radiman, Shahidan; Zakaria, Azmi; Soltaninejad, Sepideh
2014-01-01
Silver nanoparticles were successfully prepared in two different solvents using a microwave heating technique, with various irradiation times. The silver nanoparticles were dispersed in polar liquids (distilled water and ethylene glycol) without any other reducing agent, in the presence of the stabilizer polyvinylpyrrolidone (PVP). The optical properties, thermal properties, and morphology of the synthesized silver particles were characterized using ultraviolet-visible spectroscopy, photopyroelectric technique, and transmission electron microscopy. It was found that for the both solvents, the effect of microwave irradiation was mainly on the particles distribution, rather than the size, which enabled to make stable and homogeneous silver nanofluids. The individual spherical nanostructure of self-assembled nanoparticles has been formed during microwave irradiation. Ethylene glycol solution, due to its special properties, such as high dielectric loss, high molecular weight, and high boiling point, can serve as a good solvent for microwave heating and is found to be a more suitable medium than the distilled water. A photopyroelectric technique was carried out to measure thermal diffusivity of the samples. The precision and accuracy of this technique was established by comparing the measured thermal diffusivity of the distilled water and ethylene glycol with values reported in the literature. The thermal diffusivity ratio of the silver nanofluids increased up to 1.15 and 1.25 for distilled water and ethylene glycol, respectively.
Fabrication of a nanostructure thermal property measurement platform.
Harris, C T; Martinez, J A; Shaner, E A; Huang, J Y; Swartzentruber, B S; Sullivan, J P; Chen, G
2011-07-08
Measurements of the electrical and thermal transport properties of one-dimensional nanostructures (e.g. nanotubes and nanowires) are typically obtained without detailed knowledge of the specimen's atomic-scale structure or defects. To address this deficiency, we have developed a microfabricated, chip-based characterization platform that enables both transmission electron microscopy (TEM) of the atomic structure and defects as well as measurement of the thermal transport properties of individual nanostructures. The platform features a suspended heater line that physically contacts the center of a suspended nanostructure/nanowire that was placed using in situ scanning electron microscope nanomanipulators. Suspension of the nanostructure across a through-hole enables TEM characterization of the atomic and defect structure (dislocations, stacking faults, etc) of the test sample. This paper explains, in detail, the processing steps involved in creating this thermal property measurement platform. As a model study, we report the use of this platform to measure the thermal conductivity and defect structure of a GaN nanowire.
Calculation of Thermally-Induced Displacements in Spherically Domed Ion Engine Grids
NASA Technical Reports Server (NTRS)
Soulas, George C.
2006-01-01
An analytical method for predicting the thermally-induced normal and tangential displacements of spherically domed ion optics grids under an axisymmetric thermal loading is presented. A fixed edge support that could be thermally expanded is used for this analysis. Equations for the displacements both normal and tangential to the surface of the spherical shell are derived. A simplified equation for the displacement at the center of the spherical dome is also derived. The effects of plate perforation on displacements and stresses are determined by modeling the perforated plate as an equivalent solid plate with modified, or effective, material properties. Analytical model results are compared to the results from a finite element model. For the solid shell, comparisons showed that the analytical model produces results that closely match the finite element model results. The simplified equation for the normal displacement of the spherical dome center is also found to accurately predict this displacement. For the perforated shells, the analytical solution and simplified equation produce accurate results for materials with low thermal expansion coefficients.
Burkes, Douglas; Casella, Amanda J.; Gardner, Levi D.; Casella, Andrew M.; Huber, Tanja K.; Breitkreutz, Harald
2015-02-11
The Office of Material Management and Minimization Fuel Thermo-physical Characterization Project at Pacific Northwest National Laboratory (PNNL) is tasked with using PNNL facilities and processes to receive irradiated low enriched uranium-molybdenum fuel plate samples and perform analyses in support of the Office of Material Management and Minimization Reactor Conversion Program. This work is in support of the Fuel Development Pillar that is managed by Idaho National Laboratory. A key portion of the scope associated with this project was to measure the thermal properties of fuel segments harvested from plates that were irradiated in the Advanced Test Reactor. Thermal diffusivity of samples prepared from the fuel segments was measured using laser flash analysis. Two models, one developed by PNNL and the other developed by the Technische Universität München (TUM), were evaluated to extract the thermal diffusivity of the uranium-molybdenum alloy from measurements made on the irradiated, layered composites. The experimental data of the “TC” irradiated fuel segment was evaluated using both models considering a three-layer and five-layer system. Both models are in acceptable agreement with one another and indicate that the zirconium diffusion barrier has a minimal impact on the overall thermal diffusivity of the monolithic U-Mo fuel.
Quasiclassical calculation of the quasiparticle thermal conductivity in a mixed state
NASA Astrophysics Data System (ADS)
Adachi, Hiroto; Miranovic, Predrag; Ichioka, Masanori; Machida, Kazushige
2007-03-01
We report the result of calculation of the quasiparticle thermal conductivity κxx(∇T⊥B) in the vortex state of a two-dimensional superconductor. We compute κxx for both s-wave and d-wave superconductors, taking account of the spatial dependence of normal Green's function g, which is neglected in the previous studies using the Brandt-Pesch-Tewordt (BPT) method. Our results indicate that κxx based on the BPT method is slightly underestimated due to its incoherent spatial averaging procedure.
Mechanisms of Laser-Tissue Interaction: II. Tissue Thermal Properties
Ansari, Mohammad Ali; Erfanzadeh, Mohsen; Mohajerani, Ezeddin
2013-01-01
Laser-tissue interaction is of great interest due to its significant application in biomedical optics in both diagnostic and treatment purposes. Major aspects of the laser-tissue interaction which has to be considered in biomedical studies are the thermal properties of the tissue and the thermal changes caused by the interaction of light and tissue. In this review paper the effects of light on the tissue at different temperatures are discussed. Then, due to the noticeable importance of studying the heat transfer quantitatively, the equations governing this phenomenon are presented. Finally a method of medical diagnosis called thermography and some of its applications are explained. PMID:25606316
Direct calculation of modal contributions to thermal conductivity via Green-Kubo modal analysis
NASA Astrophysics Data System (ADS)
Lv, Wei; Henry, Asegun
2016-01-01
We derived a new method for direct calculation of the modal contributions to thermal conductivity, which is termed Green-Kubo modal analysis (GKMA). The GKMA method combines the lattice dynamics formalism with the Green-Kubo formula for thermal conductivity, such that the thermal conductivity becomes a direct summation of modal contributions, where one need not define the phonon velocity. As a result, the GKMA method can be applied to any material/group of atoms, where the atoms vibrate around stable equilibrium positions, which includes non-stoichiometric compounds, random alloys, amorphous materials and even rigid molecules. By using molecular dynamics simulations to obtain the time history of each mode’s contribution to the heat current, one naturally includes anharmonicity to full order and can obtain insight into the interactions between different modes through the cross-correlations. As an example, we applied the GMKA method to crystalline and amorphous silicon. The modal contributions at each frequency result from the analysis and thereby allow one to apply a quantum correction to the mode heat capacity to determine the temperature dependence of thermal conductivity. The predicted temperature dependent thermal conductivity for amorphous silicon shows the best agreement with experiments to date. The GKMA method provides new insight into the nature of phonon transport, as it casts the problem in terms of mode-mode correlation instead of scattering, and provides a general unified formalism that can be used to understand phonon-phonon interactions in essentially any class of materials or structures where the atoms vibrate around stable equilibrium sites.
Thermal properties of silicon nitride beams below 1 Kelvin.
Wang, G.; Yefremenko, V.; Novosad, V.; Datesman, A.; Pearson, J.; Shustakova, G.; Divan, R.; Chang, C.; McMahon, J.; Bleem, L.; Crites, A. T.; Downes, T.; Mehl, J.; Meyer, S. S.; Carlstrom, J. E.; Univ. of Chicago
2010-01-01
We have investigated the thermal transport of long, narrow beams of silicon nitride at cryogenic temperatures. Simultaneously employing a superconducting Transition Edge Sensor (TES) as both a heater and a sensor, we measured the thermal conductance of 1 {micro}m thick silicon nitride beams of different lateral dimensions. Based upon these measurements, we calculate the thermal parameters of the beams. We utilize a boundary limited phonon scattering model and assume the phonon mean free path to be temperature independent in the calculation. In the temperature range from 300 mK to 530 mK, the following results are obtained for 20 (30) {micro}m beams: the volume heat capacity is 0.083 T+0.509 T{sup 3} J/m{sup 3}-K, the width dependent phonon mean free path is 9.60 (11.05) {micro}m, and the width dependent thermal conductivity is 5.60 x 10{sup -3} T+3.41 x 10{sup -2} T{sup 3} (6.50 x 10{sup -3} T+3.93 x 10{sup -2} T{sup 3}) W/m-K.
Thermal and Thermoelectric Properties of Nanostructured Materials and Interfaces
NASA Astrophysics Data System (ADS)
Liao, Hao-Hsiang
Many modern technologies are enabled by the use of thin films and/or nanostructured composite materials. For example, many thermoelectric devices, solar cells, power electronics, thermal barrier coatings, and hard disk drives contain nanostructured materials where the thermal conductivity of the material is a critical parameter for the device performance. At the nanoscale, the mean free path and wavelength of heat carriers may become comparable to or smaller than the size of a nanostructured material and/or device. For nanostructured materials made from semiconductors and insulators, the additional phonon scattering mechanisms associated with the high density of interfaces and boundaries introduces additional resistances that can significantly change the thermal conductivity of the material as compared to a macroscale counterpart. Thus, better understanding and control of nanoscale heat conduction in solids is important scientifically and for the engineering applications mentioned above. In this dissertation, I discuss my work in two areas dealing with nanoscale thermal transport: (1) I describe my development and advancement of important thermal characterization tools for measurements of thermal and thermoelectric properties of a variety of materials from thin films to nanostructured bulk systems, and (2) I discuss my measurements on several materials systems done with these characterization tools. First, I describe the development, assembly, and modification of a time-domain thermoreflectance (TDTR) system that we use to measure the thermal conductivity and the interface thermal conductance of a variety of samples including nanocrystalline alloys of Ni-Fe and Co-P, bulk metallic glasses, and other thin films. Next, a unique thermoelectric measurement system was designed and assembled for measurements of electrical resistivity and thermopower of thermoelectric materials in the temperature range of 20 to 350 °C. Finally, a commercial Anter Flashline 3000 thermal
40 CFR 80.66 - Calculation of reformulated gasoline properties.
Code of Federal Regulations, 2012 CFR
2012-07-01
... properties. 80.66 Section 80.66 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... reformulated gasoline properties. (a) All volume measurements required by these regulations shall be... blend, based upon its percentage oxygenate by volume and density, shall exclude denaturants and...
Thermal properties of poly(3-hydroxybutyrate)/vegetable fiber composites
NASA Astrophysics Data System (ADS)
Vitorino, Maria B. C.; Reul, Lízzia T. A.; Carvalho, Laura H.; Canedo, Eduardo L.
2015-05-01
The present work studies the thermal properties of composites of poly(3-hydroxybutyrate) (PHB) - a fully biodegradable semi-crystalline thermo-plastic obtained from renewable resources through low-impact biotechno-logical process, biocompatible and non-toxic - and vegetable fiber from the fruit (coconut) of babassu palm tree. PHB is a highly crystalline resin and this characteristic leads to suboptimal properties in some cases. Consequently, thermal properties, in particular those associated with the crystallization of the matrix, are important to judge the suitability of the compounds for specific applications. PHB/babassu composites with 0-50% load were prepared in an internal mixer. Two different types of babassu fibers with two different particle size ranges were compounded with PHB and test specimens molded by compression. Melting and crystallization behavior were studied by differential scanning calorimetry (DSC) at heating/cooling rates between 2 and 30°C/min. Several parameters, including melting point, crystallization temperature, crystallinity, and rate of crystallization, were estimated as functions of load and heating/cooling rates. Results indicate that fibers do not affect the melting process, but facilitate crystallization from the melt. Crystallization temperatures are 30 to 40°C higher for the compounds compared with the neat resin. However, the amount of fiber added has little effect on crystallinity and the degree of crystallinity is hardly affected by the load. Fiber type and initial particle size do not have a significant effect on thermal properties.
Strain-modulated electronic and thermal transport properties of two-dimensional O-silica
NASA Astrophysics Data System (ADS)
Han, Yang; Qin, Guangzhao; Jungemann, Christoph; Hu, Ming
2016-07-01
Silica is one of the most abundant materials in the Earth’s crust and is a remarkably versatile and important engineering material in various modern science and technology. Recently, freestanding and well-ordered two-dimensional (2D) silica monolayers with octahedral (O-silica) building blocks were found to be theoretically stable by (Wang G et al 2015 J. Phys. Chem. C 119 15654-60). In this paper, by performing first-principles calculations, we systematically investigated the electronic and thermal transport properties of 2D O-silica and also studied how these properties can be tuned by simple mechanical stretching. Unstrained 2D O-silica is an insulator with an indirect band gap of 6.536 eV. The band gap decreases considerably with bilateral strain up to 29%, at which point a semiconductor-metal transition occurs. More importantly, the in-plane thermal conductivity of freestanding 2D O-silica is found to be unusually high, which is around 40 to 50 times higher than that of bulk α-quartz and more than two orders of magnitude higher than that of amorphous silica. The thermal conductivity of O-silica decreases by almost two orders of magnitude when the bilateral stretching strain reaches 10%. By analyzing the mode-dependent phonon properties and phonon-scattering channel, the phonon lifetime is found to be the dominant factor that leads to the dramatic decrease of the lattice thermal conductivity under strain. The very sensitive response of both band gap and phonon transport properties to the external mechanical strain will enable 2D O-silica to easily adapt to the different environment of realistic applications. Our study is expected to stimulate experimental exploration of further physical and chemical properties of 2D silica systems, and offers perspectives on modulating the electronic and thermal properties of related low-dimensional structures for applications such as thermoelectric, photovoltaic, and optoelectronic devices.
Berna, G. A; Bohn, M. P.; Rausch, W. N.; Williford, R. E.; Lanning, D. D.
1981-01-01
FRAPCON-2 is a FORTRAN IV computer code that calculates the steady state response of light Mater reactor fuel rods during long-term burnup. The code calculates the temperature, pressure, deformation, and tai lure histories of a fuel rod as functions of time-dependent fuel rod power and coolant boundary conditions. The phenomena modeled by the code include (a) heat conduction through the fuel and cladding, (b) cladding elastic and plastic deformation, (c) fuel-cladding mechanical interaction, (d) fission gas release, (e} fuel rod internal gas pressure, (f) heat transfer between fuel and cladding, (g) cladding oxidation, and (h) heat transfer from cladding to coolant. The code contains necessary material properties, water properties, and heat transfer correlations. FRAPCON-2 is programmed for use on the CDC Cyber 175 and 176 computers. The FRAPCON-2 code Is designed to generate initial conditions for transient fuel rod analysis by either the FRAP-T6 computer code or the thermal-hydraulic code, RELAP4/MOD7 Version 2.
This cost calculator is designed as a guide for municipal or local governments to assist in calculating their expected costs of implementing and conducting long-term stewardship of institutional controls and engineering controls at brownfield properties.
NASA Astrophysics Data System (ADS)
Chemia, Zurab; Dolejš, David; Steinle-Neumann, Gerd
2015-10-01
We explore the effects of variable material properties, phase transformations, and metamorphic devolatilization reactions on the thermal structure of a subducting slab using thermodynamic phase equilibrium calculations combined with a thermal evolution model. The subducting slab is divided into three layers consisting of oceanic sediments, altered oceanic crust, and partially serpentinized or anhydrous harzburgite. Solid-fluid equilibria and material properties are computed for each layer individually to illustrate distinct thermal consequences when chemical and mechanical homogenization within the slab is limited. Two extreme scenarios are considered for a newly forming fluid phase: complete retention in the rock pore space or instantaneous fluid escape due to porosity collapse. Internal heat generation or consumption due to variable heat capacity, compressional work, and energetics of progressive metamorphic and devolatilization reactions contribute to the thermal evolution of the slab in addition to the dominating heat flux from the surrounding mantle. They can be considered as a perturbation on the temperature profile obtained in dynamic or kinematic subduction models. Our calculations indicate that subducting sediments and oceanic crust warm by 40 and 70°C, respectively, before the effect of wedge convection and heating is encountered at 1.7 GPa. Retention of fluid in the slab pore space plays a negligible role in oceanic crust and serpentinized peridotites. By contrast, the large volatile budget of oceanic sediments causes early fluid saturation and fluid-retaining sediments cool by up to 150°C compared to their fluid-free counterparts.
NASA Astrophysics Data System (ADS)
Bandriyana, B.; Utaja
2010-06-01
Thermal stratification introduces thermal shock effect which results in local stress and fatique problems that must be considered in the design of nuclear power plant components. Local stress and fatique calculation were performed on the Pressurize Surge Line piping system of the Pressurize Water Reactor of the Nuclear Power Plant. Analysis was done on the operating temperature between 177 to 343° C and the operating pressure of 16 MPa (160 Bar). The stagnant and transient condition with two kinds of stratification model has been evaluated by the two dimensional finite elements method using the ANSYS program. Evaluation of fatigue resistance is developed based on the maximum local stress using the ASME standard Code formula. Maximum stress of 427 MPa occurred at the upper side of the top half of hot fluid pipe stratification model in the transient case condition. The evaluation of the fatigue resistance is performed on 500 operating cycles in the life time of 40 years and giving the usage value of 0,64 which met to the design requirement for class 1 of nuclear component. The out surge transient were the most significant case in the localized effects due to thermal stratification.
Bandriyana, B.; Utaja
2010-06-22
Thermal stratification introduces thermal shock effect which results in local stress and fatigue problems that must be considered in the design of nuclear power plant components. Local stress and fatigue calculation were performed on the Pressurize Surge Line piping system of the Pressurize Water Reactor of the Nuclear Power Plant. Analysis was done on the operating temperature between 177 to 343 deg. C and the operating pressure of 16 MPa (160 Bar). The stagnant and transient condition with two kinds of stratification model has been evaluated by the two dimensional finite elements method using the ANSYS program. Evaluation of fatigue resistance is developed based on the maximum local stress using the ASME standard Code formula. Maximum stress of 427 MPa occurred at the upper side of the top half of hot fluid pipe stratification model in the transient case condition. The evaluation of the fatigue resistance is performed on 500 operating cycles in the life time of 40 years and giving the usage value of 0,64 which met to the design requirement for class 1 of nuclear component. The out surge transient were the most significant case in the localized effects due to thermal stratification.
Thermal Model of Europa: Calculating the Effects of Surface Topography and Radiation from Jupiter
NASA Astrophysics Data System (ADS)
Bennett, Kristen; Paige, D.; Hayne, P.; Greenhagen, B.; Schenk, P.
2010-10-01
Europa's surface temperature distribution results from global effects such as insolation and heat flow, as well as local topography and possibly active tectonic processes. Accurate surface temperature models will greatly benefit future orbital investigations searching for global-scale variations in heat flow and local thermal anomalies resulting from frictional heating on faults or diapirs (Paige et al, this meeting). At the global scale, a major challenge for such models is the strong influence of Jupiter on the solar and infrared flux at Europa's surface. At the local scale, the thermal signature is dominated by complex topography. In order to address these two problems, we developed a model that modifies the Digital Moon program created by D. Paige and S. Meeker (2009) that uses a 3-dimensional geodesic gridding scheme to calculate the surface temperature of a body due to multiple scatterings of radiation and heat flow. We can account for Jupiter's influence on Europa by including data on Jupiter's solar and infrared radiation (which accounts for roughly 30% of the radiation at Europa), and on Europa's orbit (as Europa spends several minutes out of its 3.55 day orbital period in Jupiter's shadow). To address the issue of Europa's complicated terrain, we have simulated the effects of local heat flow as well as added topography and surface roughness to the thermal model by using digital elevation models produced by Schenk and Pappalardo (2004) that show altitude changes of several hundred meters and tectonic features that may produce regions of anomalously high heat flow.
NASA Technical Reports Server (NTRS)
Zhu, Shen; Su, Ching-Hua; Li, C.; Lin, B.; Ben, H.; Scripa, R. N.; Lehoczky, S. L.; Curreri, Peter A. (Technical Monitor)
2002-01-01
Tellurium is an element for many II-VI and I-III-VI(sub 2) compounds that are useful materials for fabricating many devises. In the melt growth techniques, the thermal properties of the molten phase are important parameter for controlling growth process to improve semiconducting crystal quality. In this study, thermal diffusivity of molten tellurium has been measured by a laser flash method in the temperature range from 500 C to 900 C. A pulsed laser with 1064 nm wavelength is focused on one side of the measured sample. The thermal diffusivity can be estimated from the temperature transient at the other side of the sample. A numerical simulation based on the thermal transport process has been also performed. By numerically fitting the experimental results, both the thermal conductivity and heat capacity can be derived. A relaxation phenomenon, which shows a slow drift of the measured thermal conductivity toward the equilibrium value after cooling of the sample, was observed for the first time. The error analysis and the comparison of the results to published data measured by other techniques will be discussed in the presentation.
NASA Technical Reports Server (NTRS)
Zhu, Shen; Li, C.; Su, Ching-Hua; Lin, B.; Ben, H.; Scripa, R. N.; Lehoczky, S. L.; Curreri, Peter A. (Technical Monitor)
2002-01-01
Tellurium is an element for many II-VI and I-III-VI(sub 2) compounds that are useful materials for fabricating many devices. In the melt growth techniques, the thermal properties of the molten phase are important parameter for controlling growth process to improve semiconducting crystal quality. In this study, thermal diffusivity of molten tellurium has been measured by a laser flash method in the temperature range from 500 C to 900 C. A pulsed laser with 1064 nm wavelength is focused on one side of the measured sample. The thermal diffusivity can be estimated from the temperature transient at the other side of the sample. A numerical simulation based on the thermal transport process has been also performed. By numerically fitting the experimental results, both the thermal conductivity and heat capacity can be derived. A relaxation phenomenon, which shows a slow drift of the measured thermal conductivity toward the equilibrium value after cooling of the sample, was observed for the first time. The error analysis and the comparison of the results to published data measured by other techniques will be discussed.
Thermodynamic properties and transport coefficients of two-temperature helium thermal plasmas
NASA Astrophysics Data System (ADS)
Guo, Xiaoxue; Murphy, Anthony B.; Li, Xingwen
2017-03-01
Helium thermal plasmas are in widespread use in arc welding and many other industrial applications. Simulation of these processes relies on accurate plasma property data, such as plasma composition, thermodynamic properties and transport coefficients. Departures from LTE (local thermodynamic equilibrium) generally occur in some regions of helium plasmas. In this paper, properties are calculated allowing for different values of the electron temperature, T e, and heavy-species temperature, T h, at atmospheric pressure from 300 K to 30 000 K. The plasma composition is first calculated using the mass action law, and the two-temperature thermodynamic properties are then derived. The viscosity, diffusion coefficients, electrical conductivity and thermal conductivity of the two-temperature helium thermal plasma are obtained using a recently-developed method that retains coupling between electrons and heavy species by including the electron–heavy-species collision term in the heavy-species Boltzmann equation. It is shown that the viscosity and the diffusion coefficients strongly depend on non-equilibrium ratio θ (θ ={{T}\\text{e}}/{{T}\\text{h}} ), through the plasma composition and the collision integrals. The electrical conductivity, which depends on the electron number density and ordinary diffusion coefficients, and the thermal conductivity have similar dependencies. The choice of definition of the Debye length is shown to affect the electrical conductivity significantly for θ > 1. By comparing with literature data, it is shown that the coupling between electrons and heavy species has a significant influence on the electrical conductivity, but not on the viscosity. Plasma properties are tabulated in the supplementary data.
NASA Astrophysics Data System (ADS)
Pavlík, Zbyšek; Fiala, Lukáš; Vejmelková, Eva; Černý, Robert
2013-05-01
The effective thermal conductivity and effective specific heat capacity of hollow brick blocks are investigated as a function of moisture content. While the effective specific heat capacity as a heat storage parameter is calculated using the linear theory of mixtures, the effective thermal conductivity as a heat transport parameter is analyzed using the effective media theory. At first, the effective thermal conductivity of the dry hollow brick block is calculated using a combination of properties of the brick body and air cavities, and verified using experimental data. Then, the effective thermal conductivity of the brick body is analyzed as a function of moisture content both theoretically and experimentally, and appropriate homogenization formulas are identified. Finally, the effective thermal conductivity of the whole hollow bricks is expressed as a function of moisture content from the dry state to water saturation.
Effect of thermal modification on rheological properties of polyethylene blends
Siriprumpoonthum, Monchai; Nobukawa, Shogo; Yamaguchi, Masayuki; Satoh, Yasuo; Sasaki, Hiroko
2014-03-15
We examined the effects of thermal modification under flow field on the rheological properties of linear low-density polyethylene (LLDPE) with high molecular weight, low-density polyethylene (LDPE), and their blends, without thermal stabilizer. Although structural changes during processing are not detected by size extrusion chromatography or nuclear magnetic resonance spectroscopy, linear viscoelastic properties changed greatly, especially for the LLDPE. A cross-linking reaction took place, leading to, presumably, star-shaped long-chain branches. Consequently, the modified LLDPE, having high zero-shear viscosity, became a thermorheologically complex melt. Moreover, it should be noted that the drawdown force, defined as the uniaxial elongational force at a constant draw ratio, was significantly enhanced for the blends. Enhancement of elongational viscosity was also detected. The drawdown force and elongational viscosity are marked for the thermally modified blend as compared with those for the blend of thermally modified pure components. Intermolecular cross-linking reactions between LDPE and LLDPE, yielding polymers with more than two branch points per chain, result in marked strain-hardening in the elongational viscosity behavior even at small strain. The recovery curve of the oscillatory modulus after the shear modification is further evidence of a branched structure.
Acousto-mechanical and thermal properties of clotted blood.
Nahirnyak, Volodymyr M; Yoon, Suk Wang; Holland, Christy K
2006-06-01
The efficacy of ultrasound-assisted thrombolysis as an adjunct treatment of ischemic stroke is being widely investigated. To determine the role of ultrasound hyperthermia in the process of blood clot disruption, the acousto-mechanical and thermal properties of clotted blood were measured in vitro, namely, density, speed of sound, frequency-dependent attenuation, specific heat, and thermal conductivity. The amplitude coefficient of attenuation of the clots was determined for 120 kHz, 1.0 MHz, and 3.5 MHz ultrasound at room temperature (20 +/- 2 degrees C). The attenuation coefficient ranged from 0.10 to 0.30 Np/cm in porcine clots and from 0.09 to 0.23 Np/cm in human clots. The experimentally determined values of specific heat and thermal conductivity for porcine clotted blood are (3.2 +/- 0.5) x 10(3) J/kg x K and 0.55 +/- 0.13 W/m x K, respectively, and for human clotted blood are (3.5 +/- 0.8) x 10(3) J/kg x K and 0.59 +/- 0.11 W/m x K, respectively. Measurements of the acousto-mechanical and thermal properties of clotted blood can be helpful in theoretical modeling of ultrasound hyperthermia in ultrasound-assisted thrombolysis and other high-intensity focused ultrasound applications.
Thermal properties of the Tin odd isotopes 117,119,121Sn
NASA Astrophysics Data System (ADS)
Kadi, H.; Benhamouda, N.
2016-07-01
We propose to study the thermal properties of the odd isotopes of Tin: 117,119,121Sn. To this end, one used two methods to evaluate the properties of these elements. The first theoretical consideration uses a simple prescription to perform the calculation of these properties based on those of even-even neighboring isotopes, assuming the quasi-particle entropy extensivity. The even-even elements are treated as part of the Modified Lipkin-Nogami (MLN) method that allows to take into account the quantal and statistical fluctuations. The second theoretical approach consists of the generalization of the MLN formalism in the case of odd systems, by using the blocking technique. Then, this approach is applied to evaluate the thermal properties of the considered elements. The obtained results by both theoretical approaches are compared to the experimental data. The latter are deduced from the experimental level density within the canonical ensemble. It appears that the assumption of quasi-particle entropy extensivity at low excitation energy allows a simple and an effective treatment of thermal properties of odd nuclei. Indeed, this approach allows to give a good reproduction of experimental data in the particular in the region where the pairing transition occurs.
Rheological and thermal properties of PP-based WPC
NASA Astrophysics Data System (ADS)
Mazzanti, V.; Mollica, F.; El Kissi, N.
2014-05-01
Wood Plastic Composite (WPC) has attracted great interest in outdoor building products for the reduced cost and the possibility of using recycled materials. Nevertheless the material shows two problems: the large viscosity due to the presence of high concentrations of filler and the degradation of cellulose during processing The aim of this work was to investigate the rheological and thermal properties of WPC. The material used for the experiments was a commercial PP-based WPC compound, with different concentrations of natural fibers (30, 50, 70% wt.). The thermal properties were studied to check for degradation of natural fibers during the subsequent rheological tests. Analyzing the storage and loss moduli and the complex viscosity curves obtained using a parallel plate rheometer it was possible to observe some features related to the viscoelastic nature of the composite.
Ab initio study of structural, electronic, and thermal properties of Pt1-xPdx alloys
NASA Astrophysics Data System (ADS)
Ahmed, Shabbir; Zafar, Muhammad; Shakil, M.; Choudhary, M. A.; Hashmi, Muhammad Raza-Ur-Rehman
2017-01-01
We report a systematic theoretical study of Pt1-xPdx alloys using ab initio density functional theory (DFT) by pseudo potential method. We have used super cell approach to investigate structural, electronic and thermal properties of Platinum (Pt), Palladium (Pd) and their alloys Pt1-xPdx(x = 0.00, 0.25, 0.50, 0.75, 1.00). The calculated lattice constants and bulk moduli are in good agreement with available literature data. The results of electronic properties revealed that the alloys are metallic in nature. The thermal properties were investigated through density functional perturbation theory (DFPT) and quasi-harmonic approximation. The contribution to the free energy from the lattice vibration was calculated using the phonon densities of states (DOS) derived by means of the linear-response theory. The DFPT with quasi-harmonic approximation methods was applied to determine the phonon DOS and thermal quantities i.e., the Debye temperatures, vibration energy, entropy and constant-volume specific heat.
Computer program for calculating water and steam properties
NASA Technical Reports Server (NTRS)
Hendricks, R. C.; Peller, I. C.; Baron, A. K.
1974-01-01
Computer subprogram, WASP, accepts any two of pressure, temperature, and density as input conditions. Pressure and either entropy or enthalpy are also allowable input variables. This flexibility is especially useful in cycle analysis. Metastable calculations can also be made using WASP.
Structural and electronic properties of perylene from first principles calculations.
Fedorov, I A; Zhuravlev, Y N; Berveno, V P
2013-03-07
The electronic structure of crystalline perylene has been investigated within the framework of density functional theory including van der Waals interactions. The computations of the lattice parameters and cohesive energy have good agreement with experimental values. We have also calculated the binding distance and energy of perylene dimers, using different schemes, which include van der Waals interactions.
Optical properties of bismuth sulfide thin film prepared by thermal evaporation method
NASA Astrophysics Data System (ADS)
Kachari, T.; Rahman, A.
2015-04-01
Two types of thin films of Bi2S3 have been prepared on chemically cleaned glass substrate by thermal evaporation technique. Either by thermal evaporation of Bi2S3 powder or by thermal evaporation of bismuth and sulfur from two separate source. (Both annealed for 3 h in air inside an oven). Optical properties of these annealed films have been studied by measuring transmittance, absorbance and reflectance of the films. Optical constants such as absorption coefficient, extinction constants, refractive index, dielectric constants etc. of both types of Bi2S3 films have been calculated. Optical band gap of type (I) and (II) films have been found to be 1.647 and 1.668 eV respectively. The crystalline structure and purity of these Bi2S3 films have been studied by taking X-ray diffraction and X-ray fluorescence spectra. Surface morphology of the films has been studied by scanning electron microscopy.
Oliveira, A Virgílio M; Gaspar, Adélio R; Quintela, Divo A
2008-11-01
The present work is dedicated to a comparative analysis of calculation methods about clothing insulation with a thermal manikin operating under the thermal comfort regulation mode. The serial, global, and parallel calculation methods are considered and the thermal insulation results for garments (30) and ensembles (9) are discussed. The serial and parallel methods presents the higher and lower values, respectively, and the differences were sometimes significant. Considering the results for the effective thermal insulation, the mean values of the relative differences between the serial and global methods were 25.7% for the daily wear garments, 45.2% for the cold protective garments and 38.5% for the ensembles. The corresponding mean values for the global and parallel methods were 8.7, 15.8, and 10.5%, respectively. Since any uneven clothing insulation is to be expected as a source of error, particular care must be required when the calculation methods deal with cold protective clothing.
Thermal properties of degraded lowland peat-moorsh soils
NASA Astrophysics Data System (ADS)
Gnatowski, Tomasz
2016-04-01
Soil thermal properties, i.e.: specific heat capacity (c), thermal conductivity (K), volumetric heat capacity (C) govern the thermal environment and heat transport through the soil. Hence the precise knowledge and accurate predictions of these properties for peaty soils with high amount of organic matter are especially important for the proper forecasting of soil temperature and thus it may lead to a better assessment of the greenhouse gas emissions created by microbiological activity of the peatlands. The objective of the study was to develop the predictive models of the selected thermal parameters of peat-moorsh soils in terms of their potential applicability for forecasting changes of soil temperature in degraded ecosystems of the Middle Biebrza River Valley area. Evaluation of the soil thermal properties was conducted for the parameters: specific heat capacity (c), volumetric heat capacities of the dry and saturated soil (Cdry, Csat) and thermal conductivities of the dry and saturated soil (Kdry, Ksat). The thermal parameters were measured using the dual-needle probe (KD2-Pro) on soil samples collected from seven peaty soils, representing total 24 horizons. The surface layers were characterized by different degrees of advancement of soil degradation dependent on intensiveness of the cultivation practises (peaty and humic moorsh). The underlying soil layers contain peat deposits of different botanical composition (peat-moss, sedge-reed, reed and alder) and varying degrees of decomposition of the organic matter, from H1 to H7 (von Post scale). Based on the research results it has been shown that the specific heat capacity of the soils differs depending on the type of soil (type of moorsh and type of peat). The range of changes varied from 1276 J.kg-1.K-1 in the humic moorsh soil to 1944 J.kg-1.K-1 in the low decomposed sedge-moss peat. It has also been stated that in degraded peat soils with the increasing of the ash content in the soil the value of specific heat
NASA Astrophysics Data System (ADS)
Lindsay, L.; Kuang, Y.
2017-03-01
Intrinsic thermal resistivity critically depends on features of phonon dispersions dictated by harmonic interatomic forces and masses. Here we present the effects of functional group mass variance on vibrational properties and thermal conductivity (κ ) of functionalized graphene from first-principles calculations. We use graphane, a buckled graphene backbone with covalently bonded hydrogen atoms on both sides, as the base material and vary the mass of the hydrogen atoms to simulate the effect of mass variance from other functional groups. We find nonmonotonic behavior of κ with increasing mass of the functional group and an unusual crossover from acoustic-dominated to optic-dominated thermal transport behavior. We connect this crossover to changes in the phonon dispersion with varying mass which suppress acoustic phonon velocities, but also give unusually high velocity optic modes. Further, we show that out-of-plane acoustic vibrations contribute significantly more to thermal transport than in-plane acoustic modes despite breaking of a reflection-symmetry-based scattering selection rule responsible for their large contributions in graphene. This work demonstrates the potential for manipulation and engineering of thermal transport properties in two-dimensional materials toward targeted applications.
Lindsay, L.; Kuang, Y.
2017-03-13
Intrinsic thermal resistivity critically depends on features of phonon dispersions dictated by harmonic interatomic forces and masses. We present the effects of functional group mass variance on vibrational properties and thermal conductivity (κ ) of functionalized graphene from first principles calculations. We also use graphane, a buckled graphene backbone with covalently bonded Hydrogen atoms on both sides, as the base material and vary the mass of the Hydrogen atoms to simulate the effect of mass variance from other functional groups. We find non-monotonic behavior of κ with increasing mass of the functional group and an unusual cross-over from acoustic-dominated tomore » optic-dominated thermal transport behavior. We connect this cross-over to changes in the phonon dispersion with varying mass which suppress acoustic phonon velocities, but also give unusually high velocity optic modes. Further, we show that out-of-plane acoustic vibrations contribute significantly more to thermal transport than in-plane acoustic modes despite breaking of a reflection symmetry based scattering selection rule responsible for their large contributions in graphene. Our work demonstrates the potential for manipulation and engineering of thermal transport properties in two dimensional materials toward targeted applications.« less
Johnson, R.L.; Bauer, S.J.
1987-05-01
Presented in this report are the results of a comparative study of two candidate horizons, the welded, devitrified Topopah Spring Member ofthe Paintbrush Tuff, and the nonwelded, zeolitized Tuffaceous Beds of Calico Hills. The mechanical and thermomechanical response these two horizons was assessed by conducting thermal and thermomechanical calculations using a two-dimensional room and pillar geometry of the vertical waste emplacement option using average and limit properties for each. A modified version of the computer code ADINA (SANDIA-ADINA) containing a material model for rock masses with ubiquitous jointing was used in the calculations. Results of the calculations are presented as the units` capacity for storage of nuclear waste and stability of the emplacement room and pillar due to excavation and long-term heating. A comparison is made with a similar underground opening geometry sited in Grouse Canyon Tuff, using properties obtained from G-Tunnel - a horizon of known excavation characteristics. Long-term stability of the excavated rooms was predicted for all units, as determined by evaluating regions of predicted joint slip as the result of excavation and subsequent thermal loading, evaluating regions of predicted rock matrix failure as the result of excavation and subsequent thermal loading, and evaluating safety factors against rock matrix failure. These results were derived through considering a wide range in material properties and in situ stresses. 21 refs., 21 figs., 5 tabs.
Calculation of Permeability Change Due to Coupled Thermal-Hydrological-Mechanical Effects
S. Blair
2000-06-28
The purpose of this calculation is to provide a bounding estimate of how thermal-hydrological-mechanical (THM) behavior of rock in the region surrounding an emplacement drift in a Monitored Geologic Repository subsurface facility may affect the permeability of fractures in the rock mass forming the region. The bounding estimate will provide essential input to performance assessment analysis of the potential repository system. This calculation also supports the Near Field Environment Process Model Report (NFE PMR) and will contribute to Site Recommendation. The geologic unit being considered as a potential repository horizon at Yucca Mountain, Nevada lies within a fractured, densely welded ash-flow tuff located in the Topopah Spring Tuff member of the Paintbrush Group. Fractures form the primary conduits for fluid flow in the rock mass. Considerable analysis has been performed to characterize the thermal-hydrologic (TH) behavior of this rock unit (e.g., CRWMS M&O 2000a, pp. 83-87), and recently the dual permeability model (DKM) has proved to be an effective tool for predicting TH behavior (CRWMS M&O 2000a). The DKM uses fracture permeability as a primary input parameter, and it is well known that fracture permeability is strongly dependent on fracture deformation (Brown. 1995). Consequently, one major unknown is how deformation during heating and cooling periods may change fracture permeability. Opening of fractures increases their permeability, whereas closing reduces permeability. More importantly, shear displacement on fractures increases their permeability, and fractures undergoing shear are likely to conduct fluids. This calculation provides a bounding estimate of how heating and cooling in the rock surrounding an emplacement drift and the resulting mechanical deformation may affect the fracture permeability of the rock.
Low-rank coal thermal properties and diffusivity: Final report
Ramirez, W.F.
1987-06-01
This project developed techniques for measuring thermal properties and mass diffusivities of low-rank coals and coal powders. Using the concept of volume averaging, predictive models have been developed for these porous media properties. The Hot Wire Method was used for simultaneously measuring the thermal conductivity and thermal diffusivity of both consolidated and unconsolidated low-rank coals. A new computer-interfaced experiment is presented and sample container designs developed for both coal powders and consolidated coals. A new mathematical model, based upon volume averaging, is presented for the prediction of these porous media properties. Velocity and temperature effects on liquid-phase dispersion through unconsolidated coal were determined. Radioactive tracer data were used to determine mass diffusivities. A new predictive mathematical model is presented based upon volume averaging. Vapor-phase diffusivity measurements of organic solvents in consolidated lignite coal are reported. An unsteady-state pressure response experiment with microcomputed-based data acquisition was developed to estimate dispersion coefficients through consolidated lignite coals. The mathematical analysis of the pressure response data provides the dispersion coefficient and the adsorption coefficient. 48 refs., 59 figs., 17 tabs.
Mechanical and thermal properties of bulk ZrB2
NASA Astrophysics Data System (ADS)
Nakamori, Fumihiro; Ohishi, Yuji; Muta, Hiroaki; Kurosaki, Ken; Fukumoto, Ken-ichi; Yamanaka, Shinsuke
2015-12-01
ZrB2 appears to have formed in the fuel debris at the Fukushima Daiichi nuclear disaster site, through the reaction between Zircaloy cladding materials and the control rod material B4C. Since ZrB2 has a high melting point of 3518 K, the ceramic has been widely studied as a heat-resistant material. Although various studies on the thermochemical and thermophysical properties have been performed for ZrB2, significant differences exist in the data, possibly due to impurities or the porosity within the studied samples. In the present study, we have prepared a ZrB2 bulk sample with 93.1% theoretical density by sintering ZrB2 powder. On this sample, we have comprehensively examined the thermal and mechanical properties of ZrB2 by the measurement of specific heat, ultrasonic sound velocities, thermal diffusivity, and thermal expansion. Vickers hardness and fracture toughness were also measured and found to be 13-23 GPa and 1.8-2.8 MPa m0.5, respectively. The relationships between these properties were carefully examined in the present study.
Megchiche, E H; Amarouche, M; Mijoule, C
2007-07-25
Within the framework of density functional theory using the projector augmented-wave (PAW) method, we present some energetic properties of atomic oxygen interstitials in crystalline Ni, i.e. the insertion and activation energies of the O diffusion. Concerning the activation energy, two pathways for the migration process are studied. The charge transfer process between atomic oxygen and nickel atoms is analysed in the interstitial sites. We find that the interstitial octahedral site (O site) is lower in energy than the tetrahedral site (T site). The most favourable pathway for the migration between two octahedral sites corresponds to an intermediate metastable state located in a tetrahedral site. Concerning the charge transfers we find that the atomic oxygen ionizes as O(-) and that the electron migrates essentially from the Ni nearest neighbours of atomic oxygen. In addition, the thermal expansion contribution through the dilatation of the solid is studied. When the thermal expansion is introduced, we show that the insertion process is stabilized and that the tetrahedral insertion energy becomes nearly equal to the octahedral ones. However, the activation energy decreases with the dilatation. Taking into account the thermal expansion effects, our results are consistent with the more reliable experimental data.
Woon, D.E.; Dunning, T.H. Jr. )
1994-02-15
An accurate description of the electrical properties of atoms and molecules is critical for quantitative predictions of the nonlinear properties of molecules and of long-range atomic and molecular interactions between both neutral and charged species. We report a systematic study of the basis sets required to obtain accurate correlated values for the static dipole ([alpha][sub 1]), quadrupole ([alpha][sub 2]), and octopole ([alpha][sub 3]) polarizabilities and the hyperpolarizability ([gamma]) of the rare gas atoms He, Ne, and Ar. Several methods of correlation treatment were examined, including various orders of Moller--Plesset perturbation theory (MP2, MP3, MP4), coupled-cluster theory with and without perturbative treatment of triple excitations [CCSD, CCSD(T)], and singles and doubles configuration interaction (CISD). All of the basis sets considered here were constructed by adding even-tempered sets of diffuse functions to the correlation consistent basis sets of Dunning and co-workers. With multiply-augmented sets we find that the electrical properties of the rare gas atoms converge smoothly to values that are in excellent agreement with the available experimental data and/or previously computed results. As a further test of the basis sets presented here, the dipole polarizabilities of the F[sup [minus
Thermal properties of andesite from Popocatepetl and Volcán de Colima, México.
NASA Astrophysics Data System (ADS)
Cardenas-Sanchez, Enrique; De la Cruz-Reina, Servando; Varley, Nick
2015-04-01
The thermal conductivity (K), specific heat (Cp) and the coefficient of heat transfer surface (H) are the basic parameters to describe the process of cooling a volcanic rock fragment released in an explosive event. The analysis of the cooling process by conduction, convection and radiation of heat in volcanic rock fragments, has been limited to basalts, and various minerals such as olivine, pyroxene, quartz, etc. (Miao & Chen, 2014; Branlund & Hofmeister, 2012; Romine et al, 2012;. Schön, 2011; Stroberg et al, 2010;. Schatz & Simmons, 1972). There are no detailed studies on the thermal properties of the andesites, abundant in continental stratovolcanoes, and particularly susceptible from lava domes with frequent destruction processes, such as Popocatepetl and Volcan de Colima. Previously, we developed an algorithm for calculation of the grain-size distribution, degree of fragmentation, the thermal energy released and its possible correlation with Volcanic Explosive Index (VEI) from the cooling curves of fragments from vulcanian and strombolian explosions. These curves were obtained from sequences of time over incandescent deposits recorded at selected pixel thermal images of vulcanian activity in the Popocatepetl and Volcan de Colima, Mexico. However, the model was limited by the lack of thermal parameters of the andesites, forcing a first approximation using basalts data. We present a simple model for the cooling process using andesites samples from Popocatépetl and Volcan de Colima. First, the samples were subjected to a rounding process to minimize surface effects. Then, heated to 800 ° C were extracted from the muffle and cooling rate is measured. The thermal conductivity and coefficient of surface heat are determined using a thermal camera and three thermocouples embedded at various depths within the sample. An inversion method was implemented to determine the thermal properties parameters , by comparing the observed data regarding cooling model for a solid
Calculation and modular properties of multiloop superstring amplitudes
Danilov, G. S.
2013-06-15
Multiloop superstring amplitudes are calculated within an extensively used gauge where the two-dimensional gravitino field carries Grassmann moduli. In general, the amplitudes possess, instead of modular symmetry, symmetry with respect to modular transformation supplemented with appropriate transformations of two-dimensional local supersymmetry. If the number of loops is larger than three, the integrationmeasures are notmodular forms, while the expression for the amplitude contains integrals along the boundary of the fundamental region of the modular group.
NASA Astrophysics Data System (ADS)
Kılıçarslan, Aynur; Salmankurt, Bahadır; Duman, Sıtkı
2017-02-01
We have performed an ab initio study of the structural, electronic, dynamical and thermal properties of the cubic AuCu3-type YSn3 and YPb3 by using the density functional theory, plane-wave pseudopotential method and a linear response scheme, within the generalized gradient approximation. An analysis of the electronic density of states at the Fermi level is found to be governed by the p states of Sn and Pb atoms with some contributions from the d states of Y atoms. The obtained phonon figures indicate that these material are dynamically stable in the cubic structure. Due to the metallic behavior of the compounds, the calculated zone-center phonon modes are triply degenerate. Also the thermal properties have been examined.
Accelerating molecular property calculations with nonorthonormal Krylov space methods
NASA Astrophysics Data System (ADS)
Furche, Filipp; Krull, Brandon T.; Nguyen, Brian D.; Kwon, Jake
2016-05-01
We formulate Krylov space methods for large eigenvalue problems and linear equation systems that take advantage of decreasing residual norms to reduce the cost of matrix-vector multiplication. The residuals are used as subspace basis without prior orthonormalization, which leads to generalized eigenvalue problems or linear equation systems on the Krylov space. These nonorthonormal Krylov space (nKs) algorithms are favorable for large matrices with irregular sparsity patterns whose elements are computed on the fly, because fewer operations are necessary as the residual norm decreases as compared to the conventional method, while errors in the desired eigenpairs and solution vectors remain small. We consider real symmetric and symplectic eigenvalue problems as well as linear equation systems and Sylvester equations as they appear in configuration interaction and response theory. The nKs method can be implemented in existing electronic structure codes with minor modifications and yields speed-ups of 1.2-1.8 in typical time-dependent Hartree-Fock and density functional applications without accuracy loss. The algorithm can compute entire linear subspaces simultaneously which benefits electronic spectra and force constant calculations requiring many eigenpairs or solution vectors. The nKs approach is related to difference density methods in electronic ground state calculations and particularly efficient for integral direct computations of exchange-type contractions. By combination with resolution-of-the-identity methods for Coulomb contractions, three- to fivefold speed-ups of hybrid time-dependent density functional excited state and response calculations are achieved.
Accelerating molecular property calculations with nonorthonormal Krylov space methods
Furche, Filipp; Krull, Brandon T.; Nguyen, Brian D.; Kwon, Jake
2016-05-03
Here, we formulate Krylov space methods for large eigenvalue problems and linear equation systems that take advantage of decreasing residual norms to reduce the cost of matrix-vector multiplication. The residuals are used as subspace basis without prior orthonormalization, which leads to generalized eigenvalue problems or linear equation systems on the Krylov space. These nonorthonormal Krylov space (nKs) algorithms are favorable for large matrices with irregular sparsity patterns whose elements are computed on the fly, because fewer operations are necessary as the residual norm decreases as compared to the conventional method, while errors in the desired eigenpairs and solution vectors remain small. We consider real symmetric and symplectic eigenvalue problems as well as linear equation systems and Sylvester equations as they appear in configuration interaction and response theory. The nKs method can be implemented in existing electronic structure codes with minor modifications and yields speed-ups of 1.2-1.8 in typical time-dependent Hartree-Fock and density functional applications without accuracy loss. The algorithm can compute entire linear subspaces simultaneously which benefits electronic spectra and force constant calculations requiring many eigenpairs or solution vectors. The nKs approach is related to difference density methods in electronic ground state calculations, and particularly efficient for integral direct computations of exchange-type contractions. By combination with resolution-of-the-identity methods for Coulomb contractions, three- to fivefold speed-ups of hybrid time-dependent density functional excited state and response calculations are achieved.
Quantum Monte Carlo Calculations of Nanostructure Optical Properties
NASA Astrophysics Data System (ADS)
Williamson, Andrew
2003-03-01
Near linear scaling Quantum Monte Carlo (QMC) calculations[1] are used to calculate the optical gaps, electron affinities, and ionization potentials of silicon and germanium quantum dots ranging in size from 0 to 2 nm[2]. These QMC results are used to examine the accuracy of semi-empirical and density functional (DFT) calculations. We find optical gaps are underestimated by DFT by 1-2 eV depending on choice of functional. Corrections introduced by the time dependent formalisms are found to be minimal in these systems. Our results also show that quantum confinement in germanium is significantly greater than in silicon leading to a crossover of their optical gaps in dots between 2 and 3 nm in size, verifying recent experiment observations. [1] A. J. Williamson, R.Q. Hood and J.C. Grossman, Phys. Rev. Lett. 87, 246406-1 (2001). [2] A.J. Williamson J.C. Grossman, R.Q. Hood, A. Puzder and Giulia Galli, Phys. Rev. Lett, 89, 196803 (2002).
A program for the calculation of paraboloidal-dish solar thermal power plant performance
NASA Technical Reports Server (NTRS)
Bowyer, J. M., Jr.
1985-01-01
A program capable of calculating the design-point and quasi-steady-state annual performance of a paraboloidal-concentrator solar thermal power plant without energy storage was written for a programmable calculator equipped with suitable printer. The power plant may be located at any site for which a histogram of annual direct normal insolation is available. Inputs required by the program are aperture area and the design and annual efficiencies of the concentrator; the intercept factor and apparent efficiency of the power conversion subsystem and a polynomial representation of its normalized part-load efficiency; the efficiency of the electrical generator or alternator; the efficiency of the electric power conditioning and transport subsystem; and the fractional parasitic loses for the plant. Losses to auxiliaries associated with each individual module are to be deducted when the power conversion subsystem efficiencies are calculated. Outputs provided by the program are the system design efficiency, the annualized receiver efficiency, the annualized power conversion subsystem efficiency, total annual direct normal insolation received per unit area of concentrator aperture, and the system annual efficiency.
NASA Astrophysics Data System (ADS)
Osuský, F.; Bahdanovich, R.; Farkas, G.; Haščík, J.; Tikhomirov, G. V.
2017-01-01
The paper is focused on development of the coupled neutronics-thermal hydraulics model for the Gas-cooled Fast Reactor. It is necessary to carefully investigate coupled calculations of new concepts to avoid recriticality scenarios, as it is not possible to ensure sub-critical state for a fast reactor core under core disruptive accident conditions. Above mentioned calculations are also very suitable for development of new passive or inherent safety systems that can mitigate the occurrence of the recriticality scenarios. In the paper, the most promising fuel material compositions together with a geometry model are described for the Gas-cooled fast reactor. Seven fuel pin and fuel assembly geometry is proposed as a test case for coupled calculation with three different enrichments of fissile material in the form of Pu-UC. The reflective boundary condition is used in radial directions of the test case and vacuum boundary condition is used in axial directions. During these condition, the nuclear system is in super-critical state and to achieve a stable state (which is numerical representation of operational conditions) it is necessary to decrease the reactivity of the system. The iteration scheme is proposed, where SCALE code system is used for collapsing of a macroscopic cross-section into few group representation as input for coupled code NESTLE.
A program for the calculation of paraboloidal-dish solar thermal power plant performance
NASA Astrophysics Data System (ADS)
Bowyer, J. M., Jr.
1985-04-01
A program capable of calculating the design-point and quasi-steady-state annual performance of a paraboloidal-concentrator solar thermal power plant without energy storage was written for a programmable calculator equipped with suitable printer. The power plant may be located at any site for which a histogram of annual direct normal insolation is available. Inputs required by the program are aperture area and the design and annual efficiencies of the concentrator; the intercept factor and apparent efficiency of the power conversion subsystem and a polynomial representation of its normalized part-load efficiency; the efficiency of the electrical generator or alternator; the efficiency of the electric power conditioning and transport subsystem; and the fractional parasitic loses for the plant. Losses to auxiliaries associated with each individual module are to be deducted when the power conversion subsystem efficiencies are calculated. Outputs provided by the program are the system design efficiency, the annualized receiver efficiency, the annualized power conversion subsystem efficiency, total annual direct normal insolation received per unit area of concentrator aperture, and the system annual efficiency.
Program for the calculation of paraboloidal-dish solar thermal power plant performance
Bowyer, J.M. Jr.
1985-04-15
A program capable of calculating the design-point and quasi-steady-state annual performance of a paraboloidal-concentrator solar thermal power plant without energy storage has been written for a programmable calculator equipped with suitable printer. The power plant may be located at any site for which a histogram of annual direct normal insolation is available. Inputs required by the program are aperture area and the design and annual efficiencies of the concentrator; the intercept factor and apparent absorptance of the receiver aperture, and the receiver heat loss; the design efficiency of the power conversion subsystem and a polynomial representation of its normalized part-load efficiency; the efficiency of the electrical generator or alternator; the efficiency of the electric power conditioning and transport subsystem; and the fractional parasitic losses for the plant. (Losses to auxiliaries associated with each individual module are to be deducted when the power conversion subsystem efficiencies are calculated.) Outputs provided by the program are the system design efficiency, the annualized receiver efficiency, the annualized power conversion subsystem efficiency, the total annual direct normal insolation received per unit area of concentrator aperture, and the system annual efficiency.
Qu, Liu; Choy, Kwang-Leong; Wheatley, Richard
2016-02-18
Ceramic oxides that have high-temperature capabilities can be deposited on the superalloy components in aero engines and diesel engines to advance engine efficiency and reduce fuel consumption. This paper aims to study doping effects of Dy(3+) and Y(3+)on the thermodynamic properties of ZrO2 synthesized via a sol-gel route for a better control of the stoichiometry, combined with molecular dynamics (MD) simulation for the calculation of theoretical properties. The thermal conductivity is investigated by the MD simulation and Clarke's model. This can improve the understanding of the microstructure and thermodynamic properties of (DyY)Zr2O7 (DYZ) at the atomistic level. The phonon-defect scattering and phonon-phonon scattering processes are investigated via the theoretical calculation, which provides an effective way to study thermal transport properties of ionic oxides. The measured and predicted thermal conductivity of DYZ is lower than that of 4 mol % Y2O3 stabilized ZrO2 (4YSZ). It is discovered that DYZ is thermochemically compatible with Al2O3 at 1300 °C, whereas at 1350 °C DYZ reacts with Al2O3 forming a small amount of new phases.
Qu, Liu; Choy, Kwang-Leong; Wheatley, Richard
2016-01-01
Ceramic oxides that have high-temperature capabilities can be deposited on the superalloy components in aero engines and diesel engines to advance engine efficiency and reduce fuel consumption. This paper aims to study doping effects of Dy3+ and Y3+on the thermodynamic properties of ZrO2 synthesized via a sol-gel route for a better control of the stoichiometry, combined with molecular dynamics (MD) simulation for the calculation of theoretical properties. The thermal conductivity is investigated by the MD simulation and Clarke’s model. This can improve the understanding of the microstructure and thermodynamic properties of (DyY)Zr2O7 (DYZ) at the atomistic level. The phonon-defect scattering and phonon-phonon scattering processes are investigated via the theoretical calculation, which provides an effective way to study thermal transport properties of ionic oxides. The measured and predicted thermal conductivity of DYZ is lower than that of 4 mol % Y2O3 stabilized ZrO2 (4YSZ). It is discovered that DYZ is thermochemically compatible with Al2O3 at 1300 °C, whereas at 1350 °C DYZ reacts with Al2O3 forming a small amount of new phases. PMID:26888438
NASA Astrophysics Data System (ADS)
Qu, Liu; Choy, Kwang-Leong; Wheatley, Richard
2016-02-01
Ceramic oxides that have high-temperature capabilities can be deposited on the superalloy components in aero engines and diesel engines to advance engine efficiency and reduce fuel consumption. This paper aims to study doping effects of Dy3+ and Y3+on the thermodynamic properties of ZrO2 synthesized via a sol-gel route for a better control of the stoichiometry, combined with molecular dynamics (MD) simulation for the calculation of theoretical properties. The thermal conductivity is investigated by the MD simulation and Clarke’s model. This can improve the understanding of the microstructure and thermodynamic properties of (DyY)Zr2O7 (DYZ) at the atomistic level. The phonon-defect scattering and phonon-phonon scattering processes are investigated via the theoretical calculation, which provides an effective way to study thermal transport properties of ionic oxides. The measured and predicted thermal conductivity of DYZ is lower than that of 4 mol % Y2O3 stabilized ZrO2 (4YSZ). It is discovered that DYZ is thermochemically compatible with Al2O3 at 1300 °C, whereas at 1350 °C DYZ reacts with Al2O3 forming a small amount of new phases.
On thermal properties of hard rocks as a host environment of an underground thermal energy storage
NASA Astrophysics Data System (ADS)
Novakova, L.; Hladky, R.; Broz, M.; Novak, P.; Lachman, V.; Sosna, K.; Zaruba, J.; Metelkova, Z.; Najser, J.
2013-12-01
With increasing focus on environmentally friendly technologies waste heat recycling became an important issue. Under certain circumstances subsurface environment could be utilized to accommodate relatively large quantity of heat. Industrial waste heat produced during warm months can be stored in an underground thermal energy storage (UTES) and used when needed. It is however a complex task to set up a sustainable UTES for industrial scale. Number of parameters has to be studied and evaluated by means of thermohydromechanical and chemical coupling (THMC) before any UTES construction. Thermal characteristics of various rocks and its stability under thermal loading are amongst the most essential. In the Czech Republic study two complementary projects THMC processes during an UTES operation. The RESEN project (www.resen.cz) employs laboratory tests and experiments to characterise thermal properties of hard rocks in the Bohemian Massif. Aim of the project is to point out the most suitable rock environment in the Bohemian Massif for moderate to ultra-high temperature UTES construction (Sanyal, 2005). The VITA project (www.geology.cz/mokrsko) studies THM coupling in non-electrical temperature UTES using long term in-situ experiment. In both projects thermal properties of rocks were studied. Thermal conductivity and capacity were measured on rock samples. In addition an influence of increasing temperature and moisture content was considered. Ten hard rocks were investigated. The set included two sandstones, two ignibrites, a melaphyr, a syenite, two granites, a gneiss and a serpentinite. For each rock there were measured thermal conductivity and capacity of at least 54 dried samples. Subsequently, the samples were heated up to 380°C in 8 hours and left to cool down. Thermal characteristics were measured during the heating period and after the sample reached room temperature. Heating and cooling cycle was repeated 7 to 10 times to evaluate possible UTES-like degradation of
Braase, Lori; Papesch, Cynthia; Hurley, David
2015-04-01
The Department of Energy (DOE)-Office of Nuclear Energy (NE), Idaho National Laboratory (INL), and associated nuclear fuels programs have invested heavily over the years in infrastructure and capability development. With the current domestic and international need to develop Accident Tolerant Fuels (ATF), increasing importance is being placed on understanding fuel performance in irradiated conditions and on the need to model and validate that performance to reduce uncertainty and licensing timeframes. INL’s Thermal Properties Capability Development Workshop was organized to identify the capability needed by the various nuclear programs and list the opportunities to meet those needs. In addition, by the end of fiscal year 2015, the decision will be made on the initial thermal properties instruments to populate the shielded cell in the Irradiated Materials Characterization Laboratory (IMCL).
Thermal property measurement of thin fibers by complementary methods
NASA Astrophysics Data System (ADS)
Munro, Troy Robert
To improve measurement reliability and repeatability and resolve the orders of magnitude discrepancy between the two different measurements (via reduced model transient electrothermal and lock-in IR thermography), this dissertation details the development of three complementary methods to accurately measure the thermal properties of the natural and synthetic Nephila (N.) clavipes spider dragline fibers. The thermal conductivity and diffusivity of the dragline silk of the (N.) clavipes spider has been characterized by one research group to be 151-416 W m-1 K-1 and 6.4-12.3 x 10-5 m2 s -1, respectively, for samples with low to high strains (zero to 19.7%). Thermal diffusivity of the dragline silk of a different spider species, Araneus diadematus, has been determined by another research group as 2 x 10-7 m2 s-1 for un-stretched silk. This dissertation seeks to resolve this discrepancy by three complementary methods. The methods detailed are the transient electrothermal technique (in both reduced and full model versions), the 3o method (for both current and voltage sources), and the non-contact, photothermal, quantum-dot spectral shape-based fluorescence thermometry method. These methods were also validated with electrically conductive and non-conductive fibers. The resulting thermal conductivity of the dragline silk is 1.2 W m-1 K-1, the thermal diffusivity is 6 x 10-7 m2 s -1 and the volumetric heat capacity is 2000 kJ m-3 K-1, with an uncertainty of about 12% for each property.
Modeling the thermal properties and processing of composite materials
Pitchumani, R.
1992-01-01
The manufacture of partially cured, thermoset matrix composite systems is modeled. A generalized analysis, applicable to almost all the fiber-resin systems encountered in practice, is carried out in terms of four key dimensionless groups formed of the process and the product parameters - (1) the Damkohler number (K(sub o)) which is a relative measure of the conduction and the reaction time scales, (2) the dimensionless activation energy (E(sub o)), (3) the adiabatic reaction temperature (B(sub o)) which represents the temperature rise potential in the composite due to the heat of the cure reaction, and (4) the Biot number (B(sub i)) which characterizes the post-cure convective cooling of the composite product. Optimal cure cycles which yield a homogeneous cure in the composite, are obtained as a function of the dimensionless parameters. Design plots for the optimal cure temperature and duration are presented. Their use in practical situations is illustrated in the context of a commercially available graphite-epoxy prepreg from Hercules, which is widely used in the aerospace industry. The thermal properties of the composite namely, the transient thermal diffusivity and the steady state thermal conductivity, are essential parameters in the process modeling studies, as well for the design of composite materials for several high temperature applications. Transient heat conduction in fibrous composites is investigated with the aim of devising a criterion for the validity of the analysis of composite materials as homogeneous media having the effective thermal properties. A homogeneity criterion based on the composite thickness is derived in terms of the fiber volume fraction and the fiber diameter. The criterion, which is the first of its kind for fibrous composites, is valid in the practical range of composite parameters. An analytical means for evaluating the effective thermal diffusivity is also presented.
Ab-Initio Calculations of the Electronic Properties of Boron Nitride
NASA Astrophysics Data System (ADS)
Stewart, Anthony; Khamala, Bethuel; Hart, Daniel; Bagayoko, Diola
2014-03-01
The potential of Boron Nitride (BN) in nanotechnology is tremendous. BN in its bulk form has a wide band gap with excellent thermal and chemical stability. BN structures can be tailored using various techniques in order to obtain desired materials properties. The State-of-the-art Proton Exchange Membrane Fuel Cell (PEMFCs) technology exploits graphitized carbon as a support for platinum-type catalysts. However, some forms of carbon are susceptible to long-term durability issues such as corrosion which is a detriment to fuel cell performance and viability. Novel non-carbon supports such as BN may provide a pathway for addressing the durability and performance issues associated with carbon support materials. We present preliminary theoretical studies, using an linear combination of atomic orbital (LCAO) quantum chemistry package from Ames Laboratory, of the electronic properties of this potentially important material. Our calculated band gap of 6.48 eV for the cubic structure, obtained with an LDA potential and the BZW-EF method, is in agreement with experiment. LASIGMA/ NNSA_MSIP.
Density functional theory calculations of defect and fission gas properties in U-Si fuels
Andersson, Anders David
2016-02-03
Accident tolerant fuels (ATF) are being developed in response to the Fukushima Daiichi accident in Japan. One of the options being pursued is U-Si fuels, such as the U_{3}Si_{2} and U_{3}Si_{5} compounds, which benefit from high thermal conductivity (metallic) compared to the UO_{2} fuel (insulator or semi-conductor) used in current Light Water Reactors (LWRs). The U-Si fuels also have higher fissile density. In order to perform meaningful engineering scale nuclear fuel performance simulations, the material properties of the fuel, including the response to irradiation environments, must be known. Unfortunately, the data available for U-Si fuels are rather limited, in particular for the temperature range where LWRs would operate. The ATF HIP is using multi-scale modeling and simulations to address this knowledge gap. The present study investigates point defect and fission gas properties in U_{3}Si_{2}, which is one of the main fuel candidates, using density functional theory (DFT) calculations. Based on a few assumption regarding entropy contributions, defect and fission diffusivities are predicted. Even though uranium silicides have been shown to amorphize easily at low temperature, we assume that U_{3}Si_{2} remains crystalline under the conditions expected in Light Water Reactors (LWRs). The temperature and dose where amorphization occurs has not yet been well established.
Mechanical and thermal properties of composite material system reinforced with micro glass balloons
NASA Astrophysics Data System (ADS)
Ozawa, Y.; Watanabe, M.; Kikuchi, T.; Ishiwatari, H.
2010-06-01
The mechanical and thermal properties of polymer composites reinforced with micro glass balloons are investigated in temperature conditions. The matrix resin of the composite is epoxy resin and its dispersion is micro glassy spherical shells of Sirasu Balloon. The composite system developed is a kind of micro porous materials with lightweight. From the experimental data of bending and tension tests, mechanical behaviours of the composites were clarified, and the effects of material properties and configurations on the mechanical properties of composites were discussed from the viewpoint of micromechanical study. A homogenization theory with multi-scale analytical method has been applied in order to evaluate the composite material system in temperature conditions. Numerical calculations were performed by using a model of micro porous materials and setting properties of each material at the temperature. Analytical results for the mechanical behaviour made a good agreement with experimental result of the composites in temperature conditions.
Accelerating molecular property calculations with nonorthonormal Krylov space methods
Furche, Filipp; Krull, Brandon T.; Nguyen, Brian D.; ...
2016-05-03
Here, we formulate Krylov space methods for large eigenvalue problems and linear equation systems that take advantage of decreasing residual norms to reduce the cost of matrix-vector multiplication. The residuals are used as subspace basis without prior orthonormalization, which leads to generalized eigenvalue problems or linear equation systems on the Krylov space. These nonorthonormal Krylov space (nKs) algorithms are favorable for large matrices with irregular sparsity patterns whose elements are computed on the fly, because fewer operations are necessary as the residual norm decreases as compared to the conventional method, while errors in the desired eigenpairs and solution vectors remainmore » small. We consider real symmetric and symplectic eigenvalue problems as well as linear equation systems and Sylvester equations as they appear in configuration interaction and response theory. The nKs method can be implemented in existing electronic structure codes with minor modifications and yields speed-ups of 1.2-1.8 in typical time-dependent Hartree-Fock and density functional applications without accuracy loss. The algorithm can compute entire linear subspaces simultaneously which benefits electronic spectra and force constant calculations requiring many eigenpairs or solution vectors. The nKs approach is related to difference density methods in electronic ground state calculations, and particularly efficient for integral direct computations of exchange-type contractions. By combination with resolution-of-the-identity methods for Coulomb contractions, three- to fivefold speed-ups of hybrid time-dependent density functional excited state and response calculations are achieved.« less
Irradiation effects on thermal properties of LWR hydride fuel
NASA Astrophysics Data System (ADS)
Terrani, Kurt; Balooch, Mehdi; Carpenter, David; Kohse, Gordon; Keiser, Dennis; Meyer, Mitchell; Olander, Donald
2017-04-01
Three hydride mini-fuel rods were fabricated and irradiated at the MIT nuclear reactor with a maximum burnup of 0.31% FIMA or ∼5 MWd/kgU equivalent oxide fuel burnup. Fuel rods consisted of uranium-zirconium hydride (U (30 wt%)ZrH1.6) pellets clad inside a LWR Zircaloy-2 tubing. The gap between the fuel and the cladding was filled with lead-bismuth eutectic alloy to eliminate the gas gap and the large temperature drop across it. Each mini-fuel rod was instrumented with two thermocouples with tips that are axially located halfway through the fuel centerline and cladding surface. In-pile temperature measurements enabled calculation of thermal conductivity in this fuel as a function of temperature and burnup. In-pile thermal conductivity at the beginning of test agreed well with out-of-pile measurements on unirradiated fuel and decreased rapidly with burnup.
Faraji, Nastaran; Mat Hussin, Roslina; Saion, Elias; Yunus, W Mahmood Mat; Behzad, Kasra
2015-01-01
Summary This work describes a fast, clean and low-cost approach to synthesize ZnS–PVA nanofluids consisting of ZnS nanoparticles homogeneously distributed in a PVA solution. The ZnS nanoparticles were formed by the electrostatic force between zinc and sulfur ions induced by gamma irradiation at a dose range from 10 to 50 kGy. Several experimental characterizations were conducted to investigate the physical and chemical properties of the samples. Fourier transform infrared spectroscopy (FTIR) was used to determine the chemical structure and bonding conditions of the final products, transmission electron microscopy (TEM) for determining the shape morphology and average particle size, powder X-ray diffraction (XRD) for confirming the formation and crystalline structure of ZnS nanoparticles, UV–visible spectroscopy for measuring the electronic absorption characteristics, transient hot wire (THW) and photoacoustic measurements for measuring the thermal conductivity and thermal effusivity of the samples, from which, for the first time, the values of specific heat and thermal diffusivity of the samples were then calculated. PMID:25821695
Properties And Coefficient Program For The Calculation Of Thermodynamic Data (PAC2)
NASA Technical Reports Server (NTRS)
Mcbride, B. J.
1989-01-01
Program calculates ideal gas thermodynamic properties for any species for which molecular constant data available, and offers user choice of methodologies for performing thermodynamic calculations. PAC2 updated to PAC4. Improvements include increased user friendliness and ability to extrapolate thermodynamic properties for gases to higher temperatures using Wilhoit's formulas.
Thickness dependencies in the calculated properties of metallic ultra-thin films
Boettger, J.C.
1997-12-01
Ultra-thin film (UTF) electronic structure calculations are a common tool for investigating surface properties. For this approximation to be useful, the UTF must be thick enough that the surfaces are decoupled and the interior is bulk-like, yet thin enough that a high precision electronic structure calculation is affordable. These conditions can only be satisfied simultaneously if the properties of interest converge rapidly as the UTF thickness is increased. In this work, electronic structure calculations for Al(111) films ranging from one to twelve atoms thick are used to illustrate some of the difficulties that can arise when one attempts to determine surface properties of metals with UTF calculations.
NASA Technical Reports Server (NTRS)
Svehla, R. A.; Mcbride, B. J.
1973-01-01
A FORTRAN IV computer program for the calculation of the thermodynamic and transport properties of complex mixtures is described. The program has the capability of performing calculations such as:(1) chemical equilibrium for assigned thermodynamic states, (2) theoretical rocket performance for both equilibrium and frozen compositions during expansion, (3) incident and reflected shock properties, and (4) Chapman-Jouguet detonation properties. Condensed species, as well as gaseous species, are considered in the thermodynamic calculation; but only the gaseous species are considered in the transport calculations.
Calculation and optimization of thermoelectric cooling modes of thermally loaded elements
NASA Astrophysics Data System (ADS)
Vasil'ev, E. N.
2017-01-01
The results of calculating the characteristics of the heat-transfer process in thermoelectric cooling and temperature control are presented. The influence of the inhomogeneity of the heat flux and thermal contacts on the temperature increase of the heat-loaded element has been defined. The analysis of the cooling efficiency depending on the operating characteristics and the current strength of the power supply of thermoelectric modules, parameters of the heat-loaded element and the individual components of the system, and the conditions of the heat exchange with the external environment has been performed. It has been shown that, under certain conditions, the use of the thermoelectric modules cannot lead to a cooling of the element, but rather to heating. The possibility of optimizing the cooling to reduce the temperature of the heat-loaded element and power consumption of the thermoelectric module has been considered.
Thermal Properties of Hybrid Carbon Nanotube/Carbon Fiber Polymer
NASA Technical Reports Server (NTRS)
Kang, Jin Ho; Cano, Roberto J.; Luong, Hoa; Ratcliffe, James G.; Grimsley, Brian W.; Siochi, Emilie J.
2016-01-01
Carbon fiber reinforced polymer (CFRP) composites possess many advantages for aircraft structures over conventional aluminum alloys: light weight, higher strength- and stiffness-to-weight ratio, and low life-cycle maintenance costs. However, the relatively low thermal and electrical conductivities of CFRP composites are deficient in providing structural safety under certain operational conditions such as lightning strikes. One possible solution to these issues is to interleave carbon nanotube (CNT) sheets between conventional carbon fiber (CF) composite layers. However, the thermal and electrical properties of the orthotropic hybrid CNT/CF composites have not been fully understood. In this study, hybrid CNT/CF polymer composites were fabricated by interleaving layers of CNT sheets with Hexcel (Registered Trademark) IM7/8852 prepreg. The CNT sheets were infused with a 5% solution of a compatible epoxy resin prior to composite fabrication. Orthotropic thermal and electrical conductivities of the hybrid polymer composites were evaluated. The interleaved CNT sheets improved the in-plane thermal conductivity of the hybrid composite laminates by about 400% and the electrical conductivity by about 3 orders of magnitude.
Thermal properties of polyolefin composites with copper silicate
NASA Astrophysics Data System (ADS)
Klozinski, Arkadiusz; Jakubowska, Paulina; Ambrozewicz, Damian; Jesionowski, Teofil
2015-05-01
The aim of this work was to specify thermal properties of polyolefin composites with copper silicate. Low density polyethylene (LDPE) and polypropylene (PP) composites with 2, 4 and 8 wt % of the filler (CuO.SiO2) were analyzed. Characteristic temperatures of the polymer compositions, i.e. the melting (Tm) and crystallization temperatures (Tc), obtained by means of Differential Scanning Calorimetry (DSC), were determined. The impact of the applied additives on composites thermal stability was established using thermogravimetry measurements (TGA). Afterwards, the flammability test was performed. The measurement was complemented with the establishment of the maximum combustion temperature using infrared recording techniques and image analysis (infrared camera). One of the most important parameter of thermoplastics is the softening point which was also determined. The measurement was carried out using a Vicat apparatus. Thermal characteristic was also supplemented with an assessment of the thermal diffusivity (the parameter determining the cooling time in an injection mold). The tests were conducted using the modified Angstrom method and an infrared camera.
Evaluation of amorphous solid dispersion properties using thermal analysis techniques.
Baird, Jared A; Taylor, Lynne S
2012-04-01
Amorphous solid dispersions are an increasingly important formulation approach to improve the dissolution rate and apparent solubility of poorly water soluble compounds. Due to their complex physicochemical properties, there is a need for multi-faceted analytical methods to enable comprehensive characterization, and thermal techniques are widely employed for this purpose. Key parameters of interest that can influence product performance include the glass transition temperature (T(g)), molecular mobility of the drug, miscibility between the drug and excipients, and the rate and extent of drug crystallization. It is important to evaluate the type of information pertaining to the aforementioned properties that can be extracted from thermal analytical measurements, in addition to considering any inherent assumptions or limitations of the various analytical approaches. Although differential scanning calorimetry (DSC) is the most widely used thermal analytical technique applied to the characterization of amorphous solid dispersions, there are many established and emerging techniques which have been shown to provide useful information. Comprehensive characterization of fundamental material descriptors will ultimately lead to the formulation of more robust solid dispersion products.
Study on Thermal and Mechanical Properties of EPDM Insulation
NASA Astrophysics Data System (ADS)
Zhang, Zhong-Shui; Xu, Jin-Sheng; Chen, Xiong; Jiang, Jing
As the most common insulation material of solid rocket motors, thermal and mechanical properties of ethylene propylene diene monomer (EPDM) composite are inspected in the study. Referring to the results of thermogravimetric analysis (TGA), composition and morphology of EPDM composite in different thermal degradation degree are investigated by scanning electron microscope (SEM) to inspect the mechanism of thermal insulation. Mechanical properties of EPDM composite in the state of pyrolysis are investigated by uniaxial tensile tests. At the state of initial pyrolysis, composite belongs to the category of hyperelastic-viscoelastic material. The tendency of tensile strength increased and elongation decreased with increasing of heating temperature. Composite behaves as the linear rule at the state of late pyrolysis, which belongs to the category of bittle. The elasticity modulus of curves are almost the same while the heating temperature ranges from 200°C to 300°C, and then gradually go down. The tensile strength of pyrolytic material reach the highest at the heating temperature of 300°C, and the virgin material has the largest elongation.
NASA Astrophysics Data System (ADS)
Hajilar, Shahin; Shafei, Behrouz
2016-12-01
The structural, thermal, and mechanical properties of portlandite, the primary solid phase of ordinary hydrated cement paste, are investigated using the molecular dynamics method. To understand the effects of temperature on the structural properties of portlandite, the coefficients of thermal expansion of portlandite are determined in the current study and validated with what reported from the experimental tests. The atomic structure of portlandite equilibrated at various temperatures is then subjected to uniaxial tensile strains in the three orthogonal directions and the stress-strain curves are developed. Based on the obtained results, the effect of the direction of straining on the mechanical properties of portlandite is investigated in detail. Structural damage analysis is performed to reveal the failure mechanisms in different directions. The energies of the fractured surfaces are calculated in different directions and compared to those of the ideal surfaces available in the literature. The key mechanical properties, including tensile strength, Young's modulus, and fracture strain, are extracted from the stress-strain curves. The sensitivity of the obtained mechanical properties to temperature and strain rate is then explored in a systematic way. This leads to valuable information on how the structural and mechanical properties of portlandite are affected under various exposure conditions and loading rates.
Theory and calculation of water distribution in bentonite in a thermal field
Carnahan, C.L.
1988-09-01
Highly compacted bentonite is under consideration for use as a buffer material in geological repositories for high-level radioactive wastes. To assess the suitability of bentonite for this use, it is necessary to be able to predict the rate and spatial extent of water uptake and water distribution in highly compacted bentonite in the presence of thermal gradients. The ''Buffer Mass Test'' (BMT) was conducted by workers in Sweden as part of the Stripa Project. The BMT measured uptake and spatial distributions of water infiltrating annuli of compacted MX-80 sodium bentonite heated from within and surrounded by granite rock; the measurements provided a body of data very valuable for comparison to results of theoretical calculations. Results of experiments on adsorption of water by highly compacted MX-80 bentonite have been reported by workers in Switzerland. The experiments included measurements of heats of immersion and adsorption-desorption isotherms. These measurements provide the basis for prediction of water vapor pressures in equilibrium with bentonite having specified adsorbed water contents at various temperatures. The present work offers a phenomenological description of the processes influencing movement of water in compacted bentonite in the presence of a variable thermal field. The theory is applied to the bentonite buffer-water system in an assumed steady state of heat and mass transport, using critical data derived from the experimental work done in Switzerland. Results of the theory are compared to distributions of absorbed water in buffers observed in the Swedish BMT experiments. 9 refs., 2 figs.
The electronic, magnetic and thermal properties of actinide monocarbides: A first principles study
NASA Astrophysics Data System (ADS)
Soni, Pooja; Pagare, Gitanjali; Rajagopalan, M.; Sanyal, Sankar P.
2012-06-01
A theoretical study on structural, electronic, magnetic and thermal properties of actinide monocarbides AnCs (An= Np and Cm), which crystallize in NaCl-type structure, has been performed using self consistent tight binding linear muffin tin orbital (TB-LMTO) method at ambient as well as at high pressure. Both non-spin and spin polarized calculations have been performed to check the magnetic stability. We observe that both the compounds are metallic in nature and ferro-magnetically stable at ambient pressure. The calculated ground state properties such as lattice constants and bulk modulus are compared with the available results. The Debye temperature is also estimated for the first time.
Thermodynamic simulation of the elastic and thermal properties of cobalt monosilicide
NASA Astrophysics Data System (ADS)
Povzner, A. A.; Filanovich, A. N.; Nogovitsyna, T. A.
2016-06-01
A self-consistent thermodynamic model is used to calculate the temperature dependences of the heat capacity, the thermal expansion coefficient, the bulk compression modulus, the density, Debye temperature, and the Grüneisen parameter of CoSi in the temperature range 0-1400 K. The calculation results agree well with the existing experimental data and can be used to predict the properties of CoSi in the temperature range that has not been experimentally studied. Cobalt monosilicide is shown to have a significant phonon anharmonicity, which can be caused by an electron-phonon interaction, and this anharmonicity should be taken into account in the simulation of its thermoelectric properties.
Synthesis, thermal and magnetic properties of RE-diborides
NASA Astrophysics Data System (ADS)
Novikov, V. V.; Matovnikov, A. V.; Volkova, O. S.; Vasil'ev, A. N.
2017-04-01
Techniques of synthesis of RE diborides (RB2) are developed (R=Tb, Dy, Ho, Er, Lu). Temperature dependence of magnetisation, a heat capacity, a lattice parameters of diborides in the range of 2-300 K are measured. According to joint calorimetric and X-ray research the analysis of a phonon component of a heat capacity and thermal expansion of RE-diborides is carried out by Debye-Einstein's models, the parameters of the model are determined. The change of magnetisation of the ferromagnetic RB2 compounds with growth of temperature caused by violation of ordering in the system of the atomic magnetic moments is compared with the change of entropy of a magnetic subsystem calculated from calorimetric data. Analytical expansion for calculation of a magnetic component of a heat capacity by RB2 magnetisation data at the temperatures of 2-300 K is obtained.
Mechanical properties testing and results for thermal barrier coatings
NASA Technical Reports Server (NTRS)
Cruse, Thomas A.; Johnsen, B. P.; Nagy, Andrew
1995-01-01
The paper reports on several years of mechanical testing of thermal barrier coatings. The test results were generated to support the development of durability models for the coatings in heat engine applications. The test data that are reviewed include modulus, static strength, and fatigue strength data. The test methods and results are discussed, along with the significant difficulties inherent in mechanical testing of thermal barrier coating materials. The materials include 7 percent wt. and 8 percent wt. yttria, partially stabilized zirconia as well as a cermet material. Both low pressure plasma spray and electron-beam physical vapor deposited coatings were tested. The data indicate the basic trends in the mechanical properties of the coatings over a wide range of isothermal conditions. Some of the trends are correlated with material density.
Optical Property Evaluation of Next Generation Thermal Control Coatings
NASA Technical Reports Server (NTRS)
Jaworske, Donald A.; Deshpande, Mukund S.; Pierson, Edward A.
2010-01-01
Next generation white thermal control coatings were developed via the Small Business Innovative Research program utilizing lithium silicate chemistry as a binder. Doping of the binder with additives yielded a powder that was plasma spray capable and that could be applied to light weight polymers and carbon-carbon composite surfaces. The plasma sprayed coating had acceptable beginning-of-life and end-of-live optical properties, as indicated by a successful 1.5 year exposure to the space environment in low Earth orbit. Recent studies also showed the coating to be durable to simulated space environments consisting of 1 keV and 10 keV electrons, 4.5 MeV electrons, and thermal cycling. Large scale deposition was demonstrated on a polymer matrix composite radiator panel, leading to the selection of the coating for use on the Gravity Recovery And Interior Laboratory (GRAIL) mission.
Lenormand, R.; Thiele, M.R.
1997-08-01
The paper describes the method and presents preliminary results for the calculation of homogenized relative permeabilities
Modified Laser Flash Method for Thermal Properties Measurements and the Influence of Heat Convection
NASA Technical Reports Server (NTRS)
Lin, Bochuan; Zhu, Shen; Ban, Heng; Li, Chao; Scripa, Rosalia N.; Su, Ching-Hua; Lehoczky, Sandor L.
2003-01-01
The study examined the effect of natural convection in applying the modified laser flash method to measure thermal properties of semiconductor melts. Common laser flash method uses a laser pulse to heat one side of a thin circular sample and measures the temperature response of the other side. Thermal diffusivity can be calculations based on a heat conduction analysis. For semiconductor melt, the sample is contained in a specially designed quartz cell with optical windows on both sides. When laser heats the vertical melt surface, the resulting natural convection can introduce errors in calculation based on heat conduction model alone. The effect of natural convection was studied by CFD simulations with experimental verification by temperature measurement. The CFD results indicated that natural convection would decrease the time needed for the rear side to reach its peak temperature, and also decrease the peak temperature slightly in our experimental configuration. Using the experimental data, the calculation using only heat conduction model resulted in a thermal diffusivity value is about 7.7% lower than that from the model with natural convection. Specific heat capacity was about the same, and the difference is within 1.6%, regardless of heat transfer models.
Moeller, P.; Nix, J.R.; Swiatecki, W.
1986-09-01
The decay properties of nuclei in many cases depend strongly on the quantum numbers of the single-particle levels in the vicinity of the Fermi surface. A striking illustration is the prolonged fission half-lives of odd nuclei relative to their even neighbors. The hindrance factor depends on the spin of unpaired odd particle and increases with increasing spin of the odd particle. The effect has been studied theoretically. For /sup 257/Fm the hindrance factor is almost ten orders of magnitude. The computer code for calculating nuclear masses calculates single-particle levels at the deformations considered as one step in the calculations. This code has been run for all nuclei considered in the 1981 mass study and the calculated single-particle levels were stored on permanent mass storage. This is actually point (I.D.1) in the research plan ('UNIFIED MODEL ...'). A computer code has been constructed for extracting levels of nuclei that are specified to the program and plotting them. Four such plots are included in this report as figs. 1-4. The levels are plotted relative to the Fermi surface of each nucleus. It is clear from the pictures that for /sup 257/Fm the calculations predict the N = 157 neutron orbital to have spin 9/2+ as is also found experimentally. The high spin is the reason for the large hindrance factor for fission of /sup 257/Fm. Figures of the type included here may be used to quickly survey larger regions of nuclei for candidates for special properties, such as unusually large hindrance factors in fission. More detailed calculations are usually required to determine the magnitude of the effects. We also include tables of the plotted single-particle levels since it is not always possible to determine the spin from an inspection of the plots, when levels are overlapping. 4 figs.
Designing energy dissipation properties via thermal spray coatings
Brake, Matthew R. W.; Hall, Aaron Christopher; Madison, Jonathan D.
2016-12-14
The coefficient of restitution is a measure of energy dissipation in a system across impact events. Often, the dissipative qualities of a pair of impacting components are neglected during the design phase. This research looks at the effect of applying a thin layer of metallic coating, using thermal spray technologies, to significantly alter the dissipative properties of a system. We studied the dissipative properties across multiple impacts in order to assess the effects of work hardening, the change in microstructure, and the change in surface topography. The results of the experiments indicate that any work hardening-like effects are likely attributablemore » to the crushing of asperities, and the permanent changes in the dissipative properties of the system, as measured by the coefficient of restitution, are attributable to the microstructure formed by the thermal spray coating. Furthermore, the microstructure appears to be robust across impact events of moderate energy levels, exhibiting negligible changes across multiple impact events.« less
Size effects on mechanical and thermal properties of thin films
NASA Astrophysics Data System (ADS)
Alam, Md Tarekul
Materials, from electronic to structural, exhibit properties that are sensitive to their composition and internal microstructures such as grain and precipitate sizes, crystalline phases, defects and dopants. Therefore, the research trend has been to obtain fundamental understanding in processing-structure-properties to develop new materials or new functionalities for engineering applications. The advent of nanotechnology has opened a new dimension to this research area because when material size is reduced to nanoscale, properties change significantly from the bulk values. This phenomenon expands the problem to 'size-processing-structure-propertiesfunctionalities'. The reinvigorated research for the last few decades has established size dependency of the material properties such as thermal conductivity, Young's modulus and yield strength, electrical resistivity, photo-conductance etc. It is generally accepted that classical physical laws can be used to scale down the properties up to 25-50 nm length-scale, below which their significant deviation or even breakdown occur. This dissertation probes the size effect from a different perspective by asking the question, if nanoscale size influences one physical domain, why it would not influence the coupling between two or more domains? Or in other words, if both mechanical and thermal properties are different at the nanoscale, can mechanical strain influence thermal conductivity? The hypothesis of size induced multi-domain coupling is therefore the foundation of this dissertation. It is catalyzed by the only few computational studies available in the literature while experimental validations have been non-existent owing to experimental challenges. The objective of this research is to validate this hypothesis, which will open a novel avenue to tune properties and functionalities of materials with the size induced multi-domain coupling. Single domain characterization itself is difficult at the nanoscale due to specimen
Spectrophotometric Properties of Thermally Anomalous Terrain on Mimas
NASA Astrophysics Data System (ADS)
Verbiscer, Anne J.; Helfenstein, Paul; Howett, Carly; Annex, Andrew; Schenk, Paul
2014-11-01
Cassini’s Composite InfraRed Spectrometer (CIRS) maps of thermal emission from Mimas reveal a V-shaped boundary, centered at 0° N and 180° W, which divides relatively warm daytime temperatures from an anomalously cooler region at low to mid-latitudes on the moon’s leading hemisphere (Howett et al. 2011, Icarus 216, 221-226). This cooler region is also warmer at night, indicating that it has high thermal inertia, and also coincides in shape and location with that of high-energy electron deposition from Saturn’s magnetosphere (Roussos et al. 2007, JGRA 112, A06214; Schenk et al. 2011, Icarus 211, 740-757). Global IR/UV color ratio maps assembled from Cassini Imaging Science Subsystem (ISS) images show a lens-shaped region of relatively blue terrain also centered on Mimas’ leading hemisphere (Schenk et al. 2011), coinciding in shape and location with the region of high thermal inertia. We present results of our analysis of Cassini ISS CL1 UV3 and IR3 filter (centered at 338 and 930 nm, respectively) images using the Hapke (2008, Icarus 195, 918-926) photometric model. We investigate whether the photometric properties of surface particles are consistent with the conclusion by Howett et al. (2011) that their high thermal inertia is produced by sintering processes due to bombardment by high energy electrons. The non-thermally anomalous surface on Mimas' trailing hemisphere exhibits a strong opposition effect, consistent with the presence of a more complex microtexture due to preferential bombardment by E ring particles. This work is supported by the NASA Cassini Data Analysis and Participating Scientists Program.
NASA Astrophysics Data System (ADS)
Fisenko, Anatoliy I.; Lemberg, Vladimir F.
2016-09-01
The knowledge of thermal radiative and thermodynamic properties of uranium and plutonium carbides under extreme conditions is essential for designing a new metallic fuel materials for next generation of a nuclear reactor. The present work is devoted to the study of the thermal radiative and thermodynamic properties of liquid and solid uranium and plutonium carbides at their melting/freezing temperatures. The Stefan-Boltzmann law, total energy density, number density of photons, Helmholtz free energy density, internal energy density, enthalpy density, entropy density, heat capacity at constant volume, pressure, and normal total emissivity are calculated using experimental data for the frequency dependence of the normal spectral emissivity of liquid and solid uranium and plutonium carbides in the visible-near infrared range. It is shown that the thermal radiative and thermodynamic functions of uranium carbide have a slight difference during liquid-to-solid transition. Unlike UC, such a difference between these functions have not been established for plutonium carbide. The calculated values for the normal total emissivity of uranium and plutonium carbides at their melting temperatures is in good agreement with experimental data. The obtained results allow to calculate the thermal radiative and thermodynamic properties of liquid and solid uranium and plutonium carbides for any size of samples. Based on the model of Hagen-Rubens and the Wiedemann-Franz law, a new method to determine the thermal conductivity of metals and carbides at the melting points is proposed.
NASA Astrophysics Data System (ADS)
Zhang, Xiaoxin; Yan, Qingzhi; Lang, Shaoting; Xia, Min; Ge, Changchun
2014-09-01
The potassium doped tungsten (W-K) grade was achieved via swaging + rolling process. The swaged + rolled W-K alloy exhibited acceptable thermal conductivity of 159.1 W/m K and ductile-to-brittle transition temperature of about 873 K while inferior mechanical properties attributed to the coarse pores and small deformation degree. Then the thermal shock, fatigue resistance of the W-K grade were characterized by an electron beam facility. Thermal shock tests were conducted at absorbed power densities varied from 0.22 to 1.1 GW/m2 in a step of 0.22 GW/m2. The cracking threshold was in the range of 0.44-0.66 GW/m2. Furthermore, recrystallization occurred in the subsurface of the specimens tested at 0.66-1.1 GW/m2 basing on the analysis of microhardness and microstructure. Thermal fatigue tests were performed at 0.44 GW/m2 up to 1000 cycles and no cracks emerged throughout the tests. Moreover, recrystallization occurred after 1000 cycles.
NASA Astrophysics Data System (ADS)
Sinka, M.; Sahmenko, G.; Korjakins, A.; Radina, L.; Bajare, D.
2015-11-01
One of the main challenges that construction industry faces today is how to address the demands for more sustainable, environmentally friendly and carbon neutral construction materials and building upkeep processes. One of the answers to these demands is lime-hemp concrete (LHC) building materials - carbon negative materials that have sufficient thermal insulation capabilities to be used as thermal insulation materials for new as well as for existing buildings. But one problem needs to be overcome before these materials can be used on a large scale - current manufacturing technology allows these materials to be used only as self-bearing thermal insulation material with large labour intensity in the manufacturing process. In order to lower the labour intensity and allow the material to be used in wider applications, a LHC block and board production is necessary, which in turn calls for the binders different from the classically used ones, as they show insufficient mechanical strength for this new use. The particular study focuses on alternative binders produced using gypsum-cement compositions ensuring they are usable in outdoor applications together with hemp shives. Physical, mechanical, thermal and water absorption properties of hemp concrete with various binders are addressed in the current study.
Rheological and thermal properties of polylactide/silicate nanocomposites films.
Ahmed, Jasim; Varshney, Sunil K; Auras, Rafeal
2010-03-01
Polylactide (DL)/polyethylene glycol/silicate nanocomposite blended biodegradable films have been prepared by solvent casting method. Rheological and thermal properties were investigated for both neat amorphous polylactide (PLA-DL form) and blend of montmorillonite (clay) and poly (ethylene glycol) (PEG). Melt rheology of the PLA individually and blends (PLA/clay; PLA/PEG; PLA/PEG/clay) were performed by small amplitude oscillation shear (SAOS) measurement. Individually, PLA showed an improvement in the viscoelastic properties in the temperature range from 180 to 190 degrees C. Incorporation of nanoclay (3% to 9% wt) was attributed by significant improvements in the elastic modulus (G') of PLA/clay blend due to intercalation at higher temperature. Both dynamic modulii of PLA/PEG blend were significantly reduced with addition of 10% PEG. Rheometric measurement could not be conducted while PLA/PEG blends containing 25% PEG. A blend of PLA/PEG/clay (68/23/9) showed liquid-like properties with excellent flexibility. Thermal analysis of different clay loading films indicated that the glass transition temperatures (T(g)) remained unaffected irrespective of clay concentration due to immobilization of polymer chain in the clay nanocomposite. PEG incorporation reduced the T(g) of the blend (PLA/PEG and PLA/PEG/clay) significantly. Both rheological and thermal analysis data supported plasticization and flexibility of the blended films. It is also interesting to study competition between PLA and PEG for the intercalation into the interlayer spacing of the clay. This study indicates that PLA/montmorillonite blend could serve as effective nano-composite for packaging and other applications.
Optical, spectral and thermal properties of natural pumice glass
NASA Astrophysics Data System (ADS)
Correcher, V.; Gomez-Ros, J. M.; Dogan, T.; Garcia-Guinea, J.; Topaksu, M.
2017-01-01
Pumice is a natural Si-rich material displaying a complex cathodo- (CL) and thermoluminescence (TL) glow curves. The UV-IR CL emission consists of (i) a UV waveband in the range of 340-420 nm,(ii) blue band at 450-480 nm and (iii) a broad emission in the green-red region (at 550-650 nm) that could be respectively linked to Non Bridging Oxygen Hole Centers (tbnd Si-O•), self-trapped excitons and point defects (Mn2+ -0.03%- and Fe -1.15%-). Thermal treatments performed on the TL glow curves allowed us to determine that the trap system could be associated with a continuum in the trap distribution, since successive thermal pretreatments in the range of 200-310 °C induce an emission that shifts linearly to higher temperatures when the thermal pretreatment (Tstop) is increased, while the intensity of the maxima decreases similarly to the peak area. The evaluation of the Ea values, s value and the trap system calculated by VHR, IR and Glow curve fitting methods considering three possible distribution function for n(E): gaussian, exponential and uniform, has given matching values for the 280 °C TL peak.
D0 Silicon Upgrade: Heat Transfer and Thermal Bowing Calculations of the D0 F-Diskl
Ratzmann, Paul M.; /Fermilab
1996-08-26
Shown in Figure 1 is a side view of the D0 F-disk assembly. SVX II chips are mounted to a flex copper/kapton Circuit, which is glued to a beryllium substrate. Figure 1 shows the top and bottom disk assemblies mounted on the cooling channel. However the disks are not mounted directly opposite one another as shown, but alternately rotate through 30{sup o} wedges mounted on either side of the cooling channel. The assumed channel temperature for these calculations is 0 C, as in the cases of the ladder cooling calculations, ref. [1] and [2]. The assumed SVX II chip power is 0.400 W. The finite difference method is used to calculate the temperature profiles of the various components. It is described in Ref. [1]. Each disk is read out using SVX II chips on both sides of the silicon. The silicon is 59.2 mm wide at its widest location. The SVX II chip location opposite the cooling channel has 8 chips mounted on the hybrid. and there are 6 SVX II chips mounted outboard of the cooling channel on the same side as the cooling channel. The SVX II chips mounted on the same side as the cooling channel read out the silicon via a jumper which passes between the beryllium substrate and the cooling channel. Currently there are two substrate materials under consideration for the jumper; kapton/copper and silicon/aluminum. The two materials have different thermal properties. so both will be considered in this note in order to compare their performance in the two different assemblies. The silicon jumper is assumed to be 0.3 mm thick with a thermal conductivity of 0.15 W/mm-K. The kapton/copper flex circuit is assumed to be 0.075 mm in thickness, with 1/2 oz copper traces (a thickness of 0.017 mm copper with 0.4 W/m-K thermal conductivity) along the length. The thermal conductivity of kapton is 0.12E-3 W/mm-K [3]. The F-Disk region is occupied by cables which extend from the barrel ladders. The cables dissipate power [4] and will contribute to warming the gas. The SVX IT chips on both the
Polymer nanocomposites with enhanced thermal and mechanical properties
NASA Astrophysics Data System (ADS)
Si, Mayu
Flame-retardant Elvacite acrylic resin/Cloisite 6A nanocomposites were prepared via direct melt intercalation. Transmission electron microscopy (TEM) micrographs showed that the high degree of exfoliation occurred, which resulted in a large improvement in thermal stability and UV absorption properties without sacrificing optical clarity. Cone calorimetry tests clearly showed that the heat release rate was far lower and more gradual in the nanocomposites than in pure resins. Additionally, Fourier transform infrared (FTIR) spectroscopy results indicated that the introduction of clay did not change the chemical structure of acrylic resins.
Elastic and thermal properties of the layered thermoelectrics BiOCuSe and LaOCuSe
NASA Astrophysics Data System (ADS)
Saha, S. K.; Dutta, G.
2016-09-01
We determine the elastic properties of the layered thermoelectrics BiOCuSe and LaOCuSe using first-principles density functional theory calculations. To predict their stability, we calculate six distinct elastic constants, where all of them are positive, and suggest mechanically stable tetragonal crystals. As elastic properties relate to the nature and the strength of the chemical bond, the latter is analyzed by means of real-space descriptors, such as the electron localization function (ELF) and Bader charge. From elastic constants, a set of related properties, namely, bulk modulus, shear modulus, Young's modulus, sound velocity, Debye temperature, Grüneisen parameter, and thermal conductivity, are evaluated. Both materials are found to be ductile in nature and not brittle. We find BiOCuSe to have a smaller sound velocity and, hence, within the accuracy of the used Slack's model, a smaller thermal conductivity than LaOCuSe. Our calculations also reveal that the elastic properties and the related lattice thermal transport of both materials exhibit a much larger anisotropy than their electronic band properties that are known to be moderately anisotropic because of a moderate effective-electron-mass anisotropy. Finally, we determine the lattice dynamical properties, such as phonon dispersion, atomic displacement, and mode Grüneisen parameters, in order to correlate the elastic response, chemical bonding, and lattice dynamics.
Thermal Properties of Structural Materials Found in Light Water Reactor Vessels
J. E. Daw; J. L. Rempe; D. L. Knudson
2009-11-01
High temperature material property data for structural materials used in existing Light Water Reactors (LWRs) are limited. Often, extrapolated values recommended in the literature differ significantly. To reduce such uncertainties, new data for SA533 Grade B, Class 1 (SA533B1) low alloy steel, Stainless Steel 304 (SS304), and Inconel 600, found in Light Water Reactor (LWR) vessels and penetrations, were acquired and tested using material property systems available at the High Temperature Test Laboratory (HTTL) at the Idaho National Laboratory (INL). Properties measured include thermal expansion, specific heat capacity, and thermal diffusivity for temperatures up to 1200 oC. From these results, thermal conductivity and density were calculated. Results show that, in some cases, previously recommended values for these material differ significantly from measured values at high temperatures. This is especially true for SA533B1, as previous data do not account for the phase transformation of this material between 740 oC and 840 oC.
The thermal and electrical properties of the promising semiconductor MXene Hf2CO2
Zha, Xian-Hu; Huang, Qing; He, Jian; He, Heming; Zhai, Junyi; Francisco, Joseph S.; Du, Shiyu
2016-01-01
With the growing interest in low dimensional materials, MXenes have also attracted considerable attention recently. In this work, the thermal and electrical properties of oxygen-functionalized M2CO2 (M = Ti, Zr, Hf) MXenes are investigated using first-principles calculations. Hf2CO2 is determined to exhibit a thermal conductivity better than MoS2 and phosphorene. The room-temperature thermal conductivity along the armchair direction is determined to be 86.25~131.2 Wm−1 K−1 with a flake length of 5~100 μm. The room temperature thermal expansion coefficient of Hf2CO2 is 6.094 × 10−6 K−1, which is lower than that of most metals. Moreover, Hf2CO2 is determined to be a semiconductor with a band gap of 1.657 eV and to have high and anisotropic carrier mobility. At room temperature, the Hf2CO2 hole mobility in the armchair direction (in the zigzag direction) is determined to be as high as 13.5 × 103 cm2V−1s−1 (17.6 × 103 cm2V−1s−1). Thus, broader utilization of Hf2CO2, such as the material for nanoelectronics, is likely. The corresponding thermal and electrical properties of Ti2CO2 and Zr2CO2 are also provided. Notably, Ti2CO2 presents relatively lower thermal conductivity but much higher carrier mobility than Hf2CO2. According to the present results, the design and application of MXene based devices are expected to be promising. PMID:27302597
Modulations of thermal properties of graphene by strain-induced phonon engineering
NASA Astrophysics Data System (ADS)
Tada, Kento; Funatani, Takashi; Konabe, Satoru; Sasaoka, Kenji; Ogawa, Matsuto; Souma, Satofumi; Yamamoto, Takahiro
2017-02-01
Modulation of the thermal properties of graphene due to strain-induced phononic band engineering was theoretically investigated by first-principles calculations based on the density functional theory. The high-energy phonon modes are found to exhibit softening owing to the strain, whereas a low-energy acoustic mode (out-of-plane mode) exhibits hardening. Moreover, the dispersion relation of the out-of-plane mode associated with the strain essentially changes from quadratic (∝ k 2) to linear (∝ k). Accordingly, the temperature dependence of the low-temperature specific heat also changes from linear (∝ T) to quadratic (∝ T 2).
Wang Weizong; Rong Mingzhe; Yan, J. D.; Spencer, Joseph W.; Murphy, A. B.
2011-11-15
Calculated thermophysical properties of nitrogen plasmas in and out of thermal equilibrium are presented. The cut-off of the partition functions due to the lowering of the ionization potential has been taken into account, together with the contributions from different core excited electronic states. The species composition and thermodynamic properties are determined numerically using the Newton-Raphson iterative method, taking into account the corrections due to Coulomb interactions. The transport properties including diffusion coefficient, viscosity, thermal conductivity, and electrical conductivity are calculated using the most recent collision interaction potentials by adopting Devoto's electron and heavy particle decoupling approach, expanded to the third-order approximation (second-order for viscosity) in the framework of Chapman-Enskog method. Results are presented in the pressure range of 0.1 atm-10 atm and in electron temperature range from 300 to 40 000 K, with the ratio of electron temperature to heavy-particle temperature varied from 1 to 20. Results are compared with those from previous works, and the influences of different definitions of the Debye length are discussed.
NASA Astrophysics Data System (ADS)
Zuo, Xianghao
Nano-particles are great additives to the thermal properties of the polymers, however, they sometimes have some disadvantages on the mechanical properties. The mixing of polymers and nano-particles such as cloisite clays, graphene, melamine polyphosphate and molybdenum disulfide, are mostly physical reactions between them. Therefore, the dispersion of the nano-particles inside the polymers is very important. As for the frame retardant of the polymers, the additives are used as three most important components during the mixing, i.e. the acid source, the carbonization agent (or char forming agent), and a blowing agent. The better the particles disperse in the polymer, the easier the material will blow and form chars during the combustion. Some of the nano-particles are used for heat conduction, which means if they have a better thermal conductivity and are better dispersed in the polymer, will certainly be benefit for the frame retardant. On the other hand, as for the gas permeability of the material, which means the gas diffuses through the polymer. Permeation is something that must be regarded highly in various polymer applications, due to their high permeability. Permeability depends on the temperature of the interaction as well as the characteristics of both the material and the permeant component. For pure polymers, since there is no additives and due to their own defects of the microstructure, gas will easily diffuse via the defects of the polymers. However, when nano-particles are mixed with the polymer, they will form barriers in the polymer and will make the gas to go a further path when it diffuses in a polymer. Hence, the well disperse of the nano-particles will be one of the key elements to reduce the gas permeation of the polymer and another factor which will impact the results will be the length over the width of the barriers. During the whole research, we focused on the most popular polymers like high density polyethylene (HDPE), low density
A computer program for calculation of spectral radiative properties of gas mixtures
NASA Technical Reports Server (NTRS)
Nealy, J. E.
1975-01-01
A computer code is described whereby calculations of radiative properties of gas mixtures may be made. The program is arranged so that distinct radiative processes for each species are computed in individual subroutines. Provision is made for calculating radiative properties in nonequilibrium situations - separate rotational, vibrational, and electronic temperatures may be used. These features should provide a flexibility not currently available in such programs. The basic equations and the program listing in FORTRAN 4 language are presented. Sample calculations are given for high temperature air and carbon dioxide and are compared to calculations made with previously developed programs.
Maienschein, J L; Wardell, J F; Weese, R K; Cunningham, B J; Tran, T D
2002-07-03
The violence of thermal explosions with energetic materials is affected by many material properties, including mechanical and thermal properties, thermal ignition kinetics, and deflagration behavior. These properties must be characterized for heated samples as well as pristine materials. We present available data for these properties for two HMX-based formulations--LX-04 and PBX-9501, and two RDX-based formulations--Composition B and PBXN-109. We draw upon separately published data on the thermal explosion violence with these materials to compare the material properties with the observed violence. We have the most extensive data on deflagration behavior of these four formulations, and we discuss the correlation of the deflagration data with the violence results. The data reported here may also be used to develop models for application in simulation codes such as ALE3D to calculate and Dredict thermal explosion violence.
Upscaling of Thermal Transport Properties in Enhanced Geothermal Systems
NASA Astrophysics Data System (ADS)
Johnson, S.; Hao, Y.; Chiaramonte, L.
2010-12-01
: Engineered Geothermal Systems (EGS) have garnered significant attention as a possible source of geographically disperse, carbon-free energy without the environmental impact of many other renewable energy sources. However, a significant barrier to the adoption of EGS is the uncertainty in whether a specific site is amenable to engineering and how fluid injection rates can affect, either through stimulation of the fracture network or through deleterious channeling of the thermal fluid, the heat extraction rate possible in a specific reservoir. Because of the uncertainties involved in determining the exact fracture network topology extant in any particular reservoir, it is desirable to have a stochastic description (distribution) of the possible heat extraction rates that could be achieved. This work provides both an approach and application of the approach for simulating several synthetic fracture networks. The approach uses a coupled geomechanics and discrete fracture network (DFN) solver coupled uni-directionally with a reservoir scale, hydro-thermal transport code, the Non-isothermal Unsaturated-Saturated Flow and Transport simulation code (NUFT), to capture the coupled hydro-thermo-mechanical behavior of these synthetic networks. Particular attention is paid to the upscaling approach used to determine effective permeability and thermal transfer coefficients that are used in the dual porosity/permeability (DKM) model employed in NUFT. This upscaling is based on a multi-scale treatment of the domain, starting with the upscaling of permeability from explicitly represented fractures in the DFN model, which considers the fracture-scale effects of fluid injection, to a finely resolved, unstructured mesh representation of the subdomain. Effective properties of this subdomain are then determined for a variety of sub-sampled discrete fracture network topologies. The result catalog of spatially correlated thermal and fluid properties are then used to populate the
Mechanical and thermal properties of nanoparticle filled epoxy nanocomposites
NASA Astrophysics Data System (ADS)
Zhao, Su
2007-12-01
One of the potential advantages of nanoparticle filled thermosets is the unique combination of mechanical properties that can be obtained. There have been several reports of improved ductility and toughness in brittle thermoset polymers due to the addition of equiaxed nanoparticles. The mechanisms leading to these improvements, however, are poorly understood. In the present study, a model system of nanoscale alumina filled bisphenol A based epoxy with two interface conditions was used to highlight the mechanisms leading to significant improvements in ductility, toughness, modulus and fatigue crack propagation resistance. It was found that the interfacial condition is critical to controlling the mechanical properties of the nanocomposites. Well-bonded APTES-Al 2O3 (3-aminopropyltriethoxysilane treated alumina) nanoparticle filled epoxy nanocomposites showed significant improvements in tensile ductility (max 39%), fracture toughness (max 26%) and fatigue crack propagation resistance, while exhibiting an increase in modulus and maintained strength. Poorly-bonded NT-Al2O3 (non-treated) nanoparticle filled epoxy nanocomposites only showed improvements in fatigue crack propagation resistance and modulus. Fracture morphology and theoretical predictions were used to study the mechanisms. The key mechanism, that significantly improved the ductility or tensile toughness of the treated nanocomposites and distinguished the treated nanocomposites from the untreated nanocomposites, is crack deflection. Crack deflection occurred much more for the well-bonded nanocomposites due to the stronger particle/matrix adhesion. Furthermore, it was found that crack deflection, interfacial debonding and particle pull-out were critical for composites with a weak interface, but that a stronger interface lead to additional mechanisms of further crack deflection, plastic deformation, microcracking and as a result a further improvement in mechanical properties. In addition, higher thermal
Ab initio calculations of the vibrational and dielectric properties of PbSnTe alloys
NASA Astrophysics Data System (ADS)
Scolfaro, Luisa; Rezende Neto, A. R.; Leite Alves, H. W.; Petersen, J. E.; Myers, T. H.; Borges, P. D.
Thermoelectric devices have promise in dealing with the challenges of the growing demand for alternative clean energy and Te-based materials well-known candidates for them. Recently, we have shown that the high values for the dielectric constant, together with anharmonic LA-TO coupling, reduces the lattice thermal conductivity and enhances the electronic conductivity in PbTe. Also, it was shown that by alloying this material with Se, the electronic conductivity of the alloys is also enhanced. But, it is not clear if the same occurs when alloying with Sn. We show, in this work, our ab initio results for the vibrational and dielectric properties of Pb1-xSnxTe alloys. The calculations were carried out by using the Density Functional Theory, and the alloys were described by both the Virtual Crystal Approximation and Cluster Expansion Method. Our results show that the anharmonic LA-TO coupling enhances and reach its maximum for Sn concentration values of 0.75, corresponding to the maximum value for the dielectric constant, which is higher than that obtained for PbTe
Mechanical and thermal properties variant of polymer optical fibers
NASA Astrophysics Data System (ADS)
Waalib-Singh, Nirmal K.; Sceats, Mark
2004-09-01
Building on recent work, this paper describes the viscoelastic behavior of microstructured polymer optical fiber (MPOF). Previously published fixed frequency dynamic mechanical and thermal properties of the two types of POFs; a commercial, C-type and MPOF fiber prototype B are compared here with multi-frequency data. As expected of viscoelastic materials, results reveal a rate dependent behavior of the fibers where storage modulus (E') increases with frequency at each temperature and the glass transition (Tg) shifts to higher temperatures. A lack of a clear (Tg) and least amount of separation between low- and high-temperature transitions at different frequencies in the C fiber clearly indicate the speciality of the fiber; it exhibits extensive elongation or rather strain-softening beyond the draw-temperature-under-load (DrTUL), which is a highly desired property for optimized hot-drawing. Strain-hardening as exhibited by the MPOF B is a brought-forward effect of the mechanical and thermal histories from its macroscopic deformation during preform structuring and fiber-forming. Polymer entanglements that cause an increase in storage modulus and 'resistive' contraction from 60 to 105°C are most likely to be networked in an orderly manner. Demonstrated again in both types of fiber, DrTUL is critical for load bearing drawing.
Thermal Properties of Unusual Local-Scale Features on Vesta
NASA Technical Reports Server (NTRS)
Capria, M.; DeSanctis, M.; Palomba, E.; Grassi, D.; Capaccioni, F.; Ammannito, E.; Combe, J.; Sunshine, J. M.; Titus, T. N.; Mittlefehldt, D. W.; Li, J.; Russell, C. T.; Raymond, C. A.
2012-01-01
On Vesta, the thermal behavior of areas of unusual albedo seen at the local scale can be related to physical properties that can provide information about the origin of those materials. We used Dawn s Visible and Infrared Mapping Spectrometer (VIR) hyperspectral cubes to retrieve surface temperatures and emissivities, with high accuracy as long as temperatures are greater than 180 K. Data acquired in the Survey phase (23 July through 29 August 2011) show several unusual surface features: 1) high-albedo (bright) and low-albedo (dark) material deposits, 2) spectrally distinct ejecta and pitted materials, 3) regions suggesting finer-grained materials. Some of the unusual dark and bright features were reobserved by VIR in the subsequent High-Altitude Mapping Orbit (HAMO) and Low- Altitude Mapping Orbit (LAMO) phases at increased pixel resolution. In this work we present temperature maps and emissivities of several local-scale features that were observed by Dawn under different illumination conditions and different local solar times. Data from VIR's IR channel show that bright regions generally correspond to regions with lower thermal emission, i.e. lower temperature, while dark regions correspond to areas with higher thermal emission, i.e. higher temperature. This behavior confirms that many of the dark appearances in the VIS mainly reflect albedo variations, and not, for example, shadowing. During maximum daily insolation, dark features in the equatorial region may rise to temperatures greater than 270 K, while brightest features stop at roughly 258 K, local solar time being similar. However, pitted materials, showing relatively low reflectance, have significantly lower temperatures, as a result of differences in composition and/or structure (e.g, average grain size of the surface regolith, porosity, etc.). To complement this work, we provide preliminary values of thermal inertia for some bright and dark features.
Thermal and microstructural properties of fine-grained material at the Viking Lander 1 site
NASA Astrophysics Data System (ADS)
Paton, M. D.; Harri, A.-M.; Savijärvi, H.; Mäkinen, T.; Hagermann, A.; Kemppinen, O.; Johnston, A.
2016-06-01
As Viking Lander 1 touched down on Mars one of its footpads fully penetrated a patch of loose fine-grained drift material. The surrounding landing site, as observed by VL-1, was found to exhibit a complex terrain consisting of a crusted surface with an assortment of rocks, large dune-like drifts and smaller patches of drift material. We use a temperature sensor attached to the buried footpad and covered in fine-grained material to determine the thermal properties of drift material at the VL-1 site. The thermal properties are used to investigate the microstructure of the drift material and understand its relevance to surface-atmosphere interactions. We obtained a thermal inertia value of 103 ± 22 tiu. This value is in the upper range of previous thermal inertia estimates of martian dust as measured from orbit and is significantly lower than the regional thermal inertia of the VL-1 site, of around 283 tiu, obtained from orbit. We estimate a thermal inertia of around 263 ± 29 tiu for the duricrust at the VL-1 site. It was noted the patch of fine-grained regolith around the footpad was about 20-30 K warmer compared to similar material beyond the thermal influence of the lander. An effective diameter of 8 ± 5 μm was calculated for the particles in the drift material. This is larger than atmospheric dust and large compared to previous estimates of the drift material particle diameter. We interpret our results as the presence of a range of particle sizes, <8 μm, in the drift material with the thermal properties being controlled by a small amount of large particles (∼8 μm) and its cohesion being controlled by a large amount of smaller particles. The bulk of the particles in the drift material are therefore likely comparable in size to that of atmospheric dust. The possibility of larger particles being locked into a fine-grained material has implications for understanding the mobilisation of wind blown materials on Mars.
Statistical Properties of Thermal Noise Driving the Brownian Particles in Fluids
NASA Astrophysics Data System (ADS)
Tóthová, Jana; Lisý, Vladimír
2016-02-01
In several recent works high-resolution interferometric detection allowed to study the Brownian motion of optically trapped microparticles in air and fluids. The observed positional fluctuations of the particles are well described by the generalized Langevin equation with the Boussinesq-Basset "history force" instead of the Stokes friction, which is valid only for the steady motion. Recently, also the time correlation function of the thermal random force Fth driving the Brownian particles through collisions with the surrounding molecules has been measured. In the present contribution we propose a method to describe the statistical properties of Fth in incompressible fluids. Our calculations show that the time decay of the correlator
Chang, Dahu; Liu, Yaming; Rao, Fengfei; Wang, Fei; Sun, Qiang; Jia, Yu
2016-06-07
Weyl semimetal (WSM) is a new type of topological quantum material for future spintronic devices. Using the first-principles density functional theory, we systematically investigated the thermal expansion properties, and the temperature dependence of isovolume heat capacity and bulk modulus in WSMs MX (M = Nb, Ta; X = P, As). We also presented the phonon dispersion curves and its variation under stress in MX and the anisotropic thermal expansion properties due to the anisotropic crystal structure in WSMs have been predicted in our calculations. Intriguing, we found that the heat capacities increase more rapidly with increasing temperature in the low temperature region for all MX. Furthermore, our results showed that the thermal expansion properties are determined mainly by the isovolume heat capacity at low temperatures, while the bulk modulus has the major effect at high temperatures. These results are useful for applications of WSMs in electronic and spintronic devices.
Busch, Anna; González-García, Núria; Lendvay, György; Olzmann, Matthias
2015-07-16
The thermal decomposition of cyanonitrene, NCN, was studied behind reflected shock waves in the temperature range 1790-2960 K at pressures near 1 and 4 bar. Highly diluted mixtures of NCN3 in argon were shock-heated to produce NCN, and concentration-time profiles of C atoms as reaction product were monitored with atomic resonance absorption spectroscopy at 156.1 nm. Calibration was performed with methane pyrolysis experiments. Rate coefficients for the reaction (3)NCN + M → (3)C + N2 + M (R1) were determined from the initial slopes of the C atom concentration-time profiles. Reaction R1 was found to be in the low-pressure regime at the conditions of the experiments. The temperature dependence of the bimolecular rate coefficient can be expressed with the following Arrhenius equation: k1(bim) = (4.2 ± 2.1) × 10(14) exp[-242.3 kJ mol(-1)/(RT)] cm(3) mol(-1) s(-1). The rate coefficients were analyzed by using a master equation with specific rate coefficients from RRKM theory. The necessary molecular data and energies were calculated with quantum chemical methods up to the CCSD(T)/CBS//CCSD/cc-pVTZ level of theory. From the topography of the potential energy surface, it follows that reaction R1 proceeds via isomerization of NCN to CNN and subsequent C-N bond fission along a collinear reaction coordinate without a tight transition state. The calculations reproduce the magnitude and temperature dependence of the rate coefficient and confirm that reaction R1 is in the low-pressure regime under our experimental conditions.
Pereira, Maria J; Amaral, Joao S; Silva, Nuno J O; Amaral, Vitor S
2016-12-01
Determining and acting on thermo-physical properties at the nanoscale is essential for understanding/managing heat distribution in micro/nanostructured materials and miniaturized devices. Adequate thermal nano-characterization techniques are required to address thermal issues compromising device performance. Scanning thermal microscopy (SThM) is a probing and acting technique based on atomic force microscopy using a nano-probe designed to act as a thermometer and resistive heater, achieving high spatial resolution. Enabling direct observation and mapping of thermal properties such as thermal conductivity, SThM is becoming a powerful tool with a critical role in several fields, from material science to device thermal management. We present an overview of the different thermal probes, followed by the contribution of SThM in three currently significant research topics. First, in thermal conductivity contrast studies of graphene monolayers deposited on different substrates, SThM proves itself a reliable technique to clarify the intriguing thermal properties of graphene, which is considered an important contributor to improve the performance of downscaled devices and materials. Second, SThM's ability to perform sub-surface imaging is highlighted by thermal conductivity contrast analysis of polymeric composites. Finally, an approach to induce and study local structural transitions in ferromagnetic shape memory alloy Ni-Mn-Ga thin films using localized nano-thermal analysis is presented.
THERMODYNAMIC PROPERTIES OF MC (M = V, Nb, Ta): FIRST-PRINCIPLES CALCULATIONS
NASA Astrophysics Data System (ADS)
Cao, Yong; Zhu, Jingchuan; Liu, Yong; Long, Zhishen
2013-07-01
Through the quasi-harmonic Debye model, the pressure and temperature dependences of linear expansion coefficient, bulk modulus, Debye temperature and heat capacity have been investigated. The calculated thermodynamic properties were compared with experimental data and satisfactory agreement is reached.
Rapid Calculation of Thermal Forces in Coarse Grained Simulation of Colloidal Particles
NASA Astrophysics Data System (ADS)
Swan, James; Fiore, Andrew; Donev, Aleksander; Balboa, Florencio
2016-11-01
In the presented work, we will demonstrate a spectrally accurate method for calculation of thermal forces in implicit solvent simulations of soft materials such as colloidal dispersions. For implicit solvent models, the stochastic forces must be drawn from a normal distribution whose covariance is a complicated function of the particle configuration. For a system of interacting N particles, drawing a single sample requires O (N3) operations, if numerically exact techniques from linear algebra are employed. So-called "fast" methods can approximate the sampling with roughly O (Nm logN) computational complexity, where m is a coefficient greater than one which depends on the configuration of the particles. The computational complexity of the presented approach is O (N(logN) d / (d + 3)) , where d is the fractal dimension of the particulate structures being modeled. Remarkably, this new approach adapts to the structure of the material under study by leveraging the algebraic structure of Ewald summation and balancing the computational effort spent evaluating near-field and far-field contributions to the hydrodynamic interactions among the suspended particles. Applications of this approach to modeling colloidal gelation and particulate suspensions will be discussed.
Thermal dependence of passive electrical properties of lizard muscle fibres.
Adams, B A
1987-11-01
1. The thermal dependence of passive electrical properties was determined for twitch fibres from the white region of the iliofibularis (IF) muscle of Anolis cristatellus (15-35 degrees C) and Sceloporus occidentalis (15-40 degrees C), and for twitch fibres from the white (15-45 degrees C) and red (15-40 degrees C) regions of the IF of Dipsosaurus dorsalis. These species differ in thermal ecology, with Anolis being the least thermophilic and Dipsosaurus the most thermophilic. 2. Iliofibularis fibres from the three species reacted similarly to changing temperature. As temperature was increased, input resistance (Rin) decreased (average R10 = 0.7), length constant (L) decreased (average R10 = 0.9), time constant (tau) decreased (average R10 = 0.8), sarcoplasmic resistivity (Rs) decreased (average R10 = 0.8) and apparent membrane resistance (Rm) decreased (average R10 = 0.7). In contrast, apparent membrane capacitance (Cm) increased with increasing temperature (average R10 = 1.3). 3. Rin, L, tau and apparent Rm were lowest in fibres from Anolis (the least thermophilic species) and highest in fibres from Dipsosaurus (the most thermophilic species). Anolis had the largest and Dipsosaurus the smallest diameter fibres (126 and 57 micron, respectively). Apparent Cm was highest in fibres from Sceloporus, which had fibres of intermediate diameter (101 micron). Rs did not differ significantly among species. 4. The effect of temperature on the passive electrical properties of these lizard fibres was similar to that reported for muscle fibres from other ectothermic animals (crustaceans, insects, fish and amphibians) but qualitatively different from that reported for some mammalian (cat tenuissimus, goat intercostal) fibres. The changes that occur in the passive electrical properties render the fibres less excitable as temperature increases.
Statistical thermodynamics of magnetic fluids. Monte Carlo calculation of the magnetic properties
Berkovskii, B.M.; Kalikmanov, V.I.; Filinov, V.S.
1988-07-01
An approach is proposed, and a modification of the Monte Carlo method is presented, for the calculation of the equilibrium thermodynamic properties of a magnetic fluid. The magnetization and mean energy are calculated. It is shown that the behavior of these properties differs from Langevin behavior, as a result of taking particle interactions into account. The results obtained are in good agreement with experimental data.
Thermal, dielectric and structural properties of Enceladus' leading face
NASA Astrophysics Data System (ADS)
Le Gall, Alice; Bonnefoy, Léa; Leyrat, Cedric; Janssen, Michael A.
2016-10-01
The Cassini RADAR was initially designed to examine the surface of Titan through the veil of its optically-opaque atmosphere. However, it is occasionally used to observe airless Saturn's moons from long range and, less frequently, during targeted flybys. In particular, the 16th targeted encounter of Enceladus (Nov. 6, 2011, flyby E16) was dedicated to the RADAR instrument which then acquired data for over 4 hours. This paper focuses on the mid-resolution (0.1-0.6REnceladus) and low-resolution polarized data (0.6-1.0REnceladus) collected during the E16 flyby in the radiometry mode of the RADAR, mainly on the leading side of the moon.In its passive mode, the RADAR records the thermal emission at 2-cm wavelength from, likely, the first meters of an icy surface. Ries and Janssen (2015) first analyzed the E16 mid-resolution radiometry observation and reported on a large-scale emissivity anomaly, possibly associated with the seemingly young tectonized Leading Hemisphere Terrain mapped by Crow-Willard and Pappalardo (2015). With the goal of further investigating the extension of the anomaly region and providing constrains on the thermal, dielectric and structural properties of Enceladus' near surface, we have re-examined this dataset as well as observations acquired in two orthogonal polarizations with the help of a thermal model. This thermal model accounts for both diurnal and seasonal variations of the incident flux, including eclipses which is of importance for the E16 observations partially occurred during a solar eclipse by Saturn.Preliminary results suggest that the average thermal inertia of the near surface of Enceladus' leading face is relatively low, as low as 40 Jm-2K-1s-1/2 . This value does not depart much from the one inferred from measurements in the IR suggesting that the surface of Enceladus is covered by a very porous regolith, at least a few meters thick. In agreement, with this interpretation, the degree of volume scattering (i.e., high
Du, Jincheng; Devanathan, Ram; Corrales, L Rene; Weber, William J
2012-01-01
First principle periodic density functional theory (DFT) calculations have been performed to understand the electronic structure, chemical bonding, phase transition, and physical properties of the zircon (in the chemical composition of ZrSiO4) and its high pressure phase reidite. Temperature effect on phase transition and thermal-mechanical properties such as heat capacity and bulk modulus have been studied by combining the equation of states obtained from DFT calculations with the quasi-harmonic Debye model to take into account the entropy contribution to free energy. Local density approximation (LDA) and generalized gradient approximation (GGA) DFT functionals have been systematically compared in predicting the structure and property of this material. It is found that the LDA functional provides a better description of the equilibrium structure and bulk modulus, while GGA predicts a transition pressure closer to experimental values. Both functionals correctly predict the relative stability of the two phases, with GGA giving slightly larger energy differences. The calculated band structures show that both zircon and reidite have indirect bandgaps and the reidite phase has a narrower bandgap than the zircon phase. The atomic charges determined using the Bader method show that bonding in reidite has a stronger covalent character.
Buyel, Johannes F; Gruchow, Hannah M; Wehner, Martin
2017-01-07
Plants can produce valuable substances such as secondary metabolites and recombinant proteins. The purification of the latter from plant biomass can be streamlined by heat treatment (blanching). A blanching apparatus can be designed more precisely if the thermal properties of the leaves are known in detail, i.e., the specific heat capacity and thermal conductivity. The measurement of these properties is time consuming and labor intensive, and usually requires invasive methods that contact the sample directly. This can reduce the product yield and may be incompatible with containment requirements, e.g., in the context of good manufacturing practice. To address these issues, a non-invasive, contact-free method was developed that determines the specific heat capacity and thermal conductivity of an intact plant leaf in about one minute. The method involves the application of a short laser pulse of defined length and intensity to a small area of the leaf sample, causing a temperature increase that is measured using a near infrared sensor. The temperature increase is combined with known leaf properties (thickness and density) to determine the specific heat capacity. The thermal conductivity is then calculated based on the profile of the subsequent temperature decline, taking thermal radiation and convective heat transfer into account. The associated calculations and critical aspects of sample handling are discussed.
Huang, Zuocai; Zhang, Lei; Pan, Wei
2013-09-15
Pure zircon and scheelite LuVO{sub 4} were prepared by solid state reaction and high-pressure route, respectively. Structure, elastic constants, lattice dynamics and thermodynamics of LuVO{sub 4} polymorphs were studied by experiments and first principles calculation. Calculations here are in good agreement with the experimental results. The phonon dispersions of LuVO{sub 4} polymorphs were studied by the linear response method. The calculated phonon dispersions show that zircon and scheelite LuVO{sub 4} phases are dynamically stable. Raman-active frequencies were measured and assigned to different modes according to the calculations. The internal frequencies shift downward after phase transition from zircon to scheelite. Born effective charge tensors elements for both phases are analyzed. The finite temperature thermodynamic properties of LuVO{sub 4} polymorphs were calculated from the obtained phonon density of states by quasi-harmonic approach. - Graphical abstract: Lutetium orthovanadate polymorphs were synthesized by SSR and HP methods and their physical and chemical properties, including lattice dynamical properties, were determined by DFT calculations and experiments. Display Omitted - Highlights: • Pure zircon and scheelite LuVO{sub 4} polymorphs were synthesized by solid state reaction and high-pressure route. • Chemical and physical properties of LuVO4 polymorphs were studied by experiments and first principles calculation. • Raman-active frequencies were measured and assigned to different modes according to the calculations. • Lattice dynamics of polymorphs were discussed in details.
Calculation of long range forces and their applications in determining gaseous properties
NASA Technical Reports Server (NTRS)
Singh, J. J.
1979-01-01
A discussion of various theoretical and experimental techniques for the calculation of long range interaction between two atomic systems at moderate separation is presented. Some applications of these techniques for obtaining gaseous properties are described. The forces between neutral molecules and metallic surfaces are also discussed and numerical values of heats of adsorption for a number of systems are calculated.
Experimental study of the effect of shallow groundwater table on soil thermal properties
NASA Astrophysics Data System (ADS)
Jiang, Jianmei; Zhao, Lin; Zeng, Yijian; Zhai, Zhe
2016-03-01
In plains areas with semi-arid climates, shallow groundwater is one of the important factors affecting soil thermal properties. In this study, soil temperature and water content were measured when groundwater tables reached 10 cm, 30 cm, and 60 cm depths (Experiment I, II, and III) by using sensors embedded at depths of 5 cm, 10 cm, 20 cm, and 30 cm for 5 days. Soil thermal properties were analyzed based on the experimental data using the simplified de Vries model. Results show that soil water content and temperature have fluctuations that coincide with the 24 h diurnal cycle, and the amplitude of these fluctuations decreased with the increase in groundwater table depth. The amplitude of soil water content at 5 cm depth decreased from 0.025 m3·m-3 in Experiment II to 0.01 m3·m-3 in Experiment III. Moreover, it should be noted that the soil temperature in Experiment III gradually went up with the lowest value increasing from 26.0°C to 28.8°C. By contrast, the trends were not evident in Experiments I and II. Results indicate that shallow groundwater has a "cooling" effect on soil in the capillary zone. In addition, calculated values of thermal conductivity and heat capacity declined with the increasing depth of the groundwater table, which is consistent with experimental results. The thermal conductivity was stable at a value of 2.3W·cm-1·K-1 in Experiment I. The average values of thermal conductivity at different soil depths in Experiment II were 1.82W·cm-1·K-1, 2.15W·cm-1·K-1, and 2.21W·cm-1·K-1, which were always higher than that in Experiment III.
Picolloto, A. M.; Mariucci, V. V. G.; Szpak, W.; Medina, A. N.; Baesso, M. L.; Astrath, N. G. C.; Astrath, F. B. G.; Bento, A. C.; Santos, A. D.; Moraes, J. C. S.
2013-11-21
The thermal wave method is applied for thermal properties measurement in fast endodontic cement (CER). This new formula is developed upon using Portland cement in gel and it was successfully tested in mice with good biocompatibility and stimulated mineralization. Recently, thermal expansion and setting time were measured, conferring to this material twice faster hardening than the well known Angelus Mineral trioxide aggregate (MTA) the feature of fast hardening (∼7 min) and with similar thermal expansion (∼12 μstrain/ °C). Therefore, it is important the knowledge of thermal properties like thermal diffusivity, conductivity, effusivity in order to match thermally the tissue environment upon its application in filling cavities of teeth. Photothermal radiometry technique based on Xe illumination was applied in CER disks 600 μm thick for heating, with prepared in four particle sizes (25, 38, 45, and 53) μm, which were added microemulsion gel with variation volumes (140, 150, 160, and 170) μl. The behavior of the thermal diffusivity CER disks shows linear decay for increase emulsion volume, and in contrast, thermal diffusivity increases with particles sizes. Aiming to compare to MTA, thermal properties of CER were averaged to get the figure of merit for thermal diffusivity as (44.2 ± 3.6) × 10{sup −3} cm{sup 2}/s, for thermal conductivity (228 ± 32) mW/cm K, the thermal effusivity (1.09 ± 0.06) W s{sup 0.5}/cm{sup 2} K and volume heat capacity (5.2 ± 0.7) J/cm{sup 3} K, which are in excellent agreement with results of a disk prepared from commercial MTA-Angelus (grain size < 10 μm using 57 μl of distilled water)
NASA Astrophysics Data System (ADS)
Picolloto, A. M.; Mariucci, V. V. G.; Szpak, W.; Medina, A. N.; Baesso, M. L.; Astrath, N. G. C.; Astrath, F. B. G.; Santos, A. D.; Moraes, J. C. S.; Bento, A. C.
2013-11-01
The thermal wave method is applied for thermal properties measurement in fast endodontic cement (CER). This new formula is developed upon using Portland cement in gel and it was successfully tested in mice with good biocompatibility and stimulated mineralization. Recently, thermal expansion and setting time were measured, conferring to this material twice faster hardening than the well known Angelus Mineral trioxide aggregate (MTA) the feature of fast hardening (˜7 min) and with similar thermal expansion (˜12 μstrain/ °C). Therefore, it is important the knowledge of thermal properties like thermal diffusivity, conductivity, effusivity in order to match thermally the tissue environment upon its application in filling cavities of teeth. Photothermal radiometry technique based on Xe illumination was applied in CER disks 600 μm thick for heating, with prepared in four particle sizes (25, 38, 45, and 53) μm, which were added microemulsion gel with variation volumes (140, 150, 160, and 170) μl. The behavior of the thermal diffusivity CER disks shows linear decay for increase emulsion volume, and in contrast, thermal diffusivity increases with particles sizes. Aiming to compare to MTA, thermal properties of CER were averaged to get the figure of merit for thermal diffusivity as (44.2 ± 3.6) × 10-3 cm2/s, for thermal conductivity (228 ± 32) mW/cm K, the thermal effusivity (1.09 ± 0.06) W s0.5/cm2 K and volume heat capacity (5.2 ± 0.7) J/cm3 K, which are in excellent agreement with results of a disk prepared from commercial MTA-Angelus (grain size < 10 μm using 57 μl of distilled water).
Optical-Fiber Thermal-Wave-Cavity Technique to Study Thermal Properties of Silver/Clay Nanofliuds
NASA Astrophysics Data System (ADS)
Noroozi, M.; Radiman, S.; Zakaria, A.; Shameli, K.; Deraman, M.; Soltaninejad, S.; Abedini, A.
2014-10-01
Thermal properties enhancement of nanofluids have varied strongly with synthesis technique, particle size and type, concentration and agglomeration with time. This study explores the possibility of changing the thermal wave signal of Ag/clay nanofluids into a thermal diffusivity measurement at well dispersion or aggregation of nanoparticles in the base fluid. Optical-Fiber Thermal-Wave-Cavity (OF-TWC) technique was achieved by using a small amount of nanofluid (only 0.2 mL) between fiber optic tip and the Pyroelectric detector and the cavity-length scan was performed. We established the accuracy and precision of this technique by comparing the thermal diffusivity of distilled water to values reported in the literature. Assuming a linear Pyroelectric signal response, the results show that adding clay reduced the thermal diffusivity of water, while increasing the Ag concentration from 1 to 5 wt.% increased the thermal diffusivity of the Ag nanofluid from 1.524×10-3 to 1.789×10-3 cm2/s. However, in particular, nanoparticles show the tendency to form aggregates over time that correlated with the performance change of thermal properties of nanofluid. Our results confirm the high sensitivity of OF-TWC technique raises the potential to be applied to measuring the optical and thermal properties of nanofluids. Furthermore, this technique allows the extraction of information not obtained using other traditional techniques.
Effects of Mass Fluctuation on Thermal Transport Properties in Bulk Bi2Te3
NASA Astrophysics Data System (ADS)
Huang, Ben; Zhai, Pengcheng; Yang, Xuqiu; Li, Guodong
2016-10-01
In this paper, we applied large-scale molecular dynamics and lattice dynamics to study the influence of mass fluctuation on thermal transport properties in bulk Bi2Te3, namely thermal conductivity (K), phonon density of state (PDOS), group velocity (v g), and mean free path (l). The results show that total atomic mass change can affect the relevant vibrational frequency on the micro level and heat transfer rate in the macro statistic, hence leading to the strength variation of the anharmonic phonon processes (Umklapp scattering) in the defect-free Bi2Te3 bulk. Moreover, it is interesting to find that the anharmonicity of Bi2Te3 can be also influenced by atomic differences of the structure such as the mass distribution in the primitive cell. Considering the asymmetry of the crystal structure and interatomic forces, it can be concluded by phonon frequency, lifetime, and velocity calculation that acoustic-optical phonon scattering shows the structure-sensitivity to the mass distribution and complicates the heat transfer mechanism, hence resulting in the low lattice thermal conductivity of Bi2Te3. This study is helpful for designing the material with tailored thermal conductivity via atomic substitution.
Physical properties of vacuum evaporated CdTe thin films with post-deposition thermal annealing
NASA Astrophysics Data System (ADS)
Chander, Subhash; Dhaka, M. S.
2015-09-01
This paper presents the physical properties of vacuum evaporated CdTe thin films with post-deposition thermal annealing. The thin films of thickness 500 nm were grown on glass and indium tin oxide (ITO) coated glass substrates employing thermal vacuum evaporation technique followed by post-deposition thermal annealing at temperature 450 °C. These films were subjected to the X-ray diffraction (XRD),UV-Vis spectrophotometer, source meter and atomic force microscopy (AFM) for structural, optical, electrical and surface morphological analysis respectively. The X-ray diffraction patterns reveal that the films have zinc-blende structure of single cubic phase with preferred orientation (111) and polycrystalline in nature. The crystallographic and optical parameters are calculated and discussed in brief. The optical band gap is found to be 1.62 eV and 1.52 eV for as-grown and annealed films respectively. The I-V characteristics show that the conductivity is decreased for annealed thin films. The AFM studies reveal that the surface roughness is observed to be increased for thermally annealed films.
Surface and thermal properties of collagen/hyaluronic acid blends containing chitosan.
Lewandowska, Katarzyna; Sionkowska, Alina; Grabska, Sylwia; Kaczmarek, Beata
2016-11-01
The structure and surface properties of binary and ternary blends containing collagen (Coll), hyaluronic acid (HA) and chitosan (Ch) were investigated by contact angle measurements, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Thin films of Coll/HA and Coll/HA/Ch blends have been formed by casting methods from aqueous acid solutions. The surface roughness, hydrophobic/hydrophilic character and thermal stability of Coll/HA were changed after addition of chitosan. Thermal stability of binary blends increase upon the addition of chitosan. The results of contact angle and the surface free energy revealed that hyaluronic acid films are more polar than collagen and chitosan films. The surface energy and its polar and dispersive components of binary and ternary blends were calculated and more hydrophilic films were produced by the addition of HA and chitosan, also resulting in more thermally stabile materials. These results demonstrate that collagen interacts with hyaluronic acid and chitosan changing the surface properties of polymer films.
Magnetic properties of Li2RuO3 as studied by NMR and LDA+DMFT calculations
NASA Astrophysics Data System (ADS)
Arapova, I. Yu.; Buzlukov, A. L.; Germov, A. Yu.; Mikhalev, K. N.; Tan, T.-Y.; Park, J.-G.; Streltsov, S. V.
2017-03-01
We present results of the combined study of the magnetic properties of Li2RuO3 by means of nuclear magnetic resonance (NMR) spectroscopy and theoretical dynamical mean-field theory (LDA+DMFT) calculations. The NMR data clearly show the onset of a thermal activation process in the high temperature region, T > 560 K, which is tentatively ascribed to the formation of the valence bond liquid. The LDA+DMFT calculations demonstrate that the magnetic response at these temperatures is mostly due to the xz/yz orbitals, while the xy orbitals of Ru still form molecular orbitals. Thus, Ru ions are in the orbital-selective state in the high temperature phase of Li2RuO3.
Synthesis and thermal properties of strontium and calcium peroxides
NASA Technical Reports Server (NTRS)
Philipp, Warren H.; Kraft, Patricia A.
1989-01-01
A practical synthesis and a discussion of some chemical properties of pure strontium peroxide and calcium peroxide are presented. The general synthesis of these peroxides involves precipitation of their octahydrates by addition of H2O2 to aqueous ammoniacal Sr(NO3)2 or CaCl2. The octahydrates are converted to the anhydrous peroxides by various dehydration techniques. A new x-ray diffraction powder pattern for CaO2 x 8H2O is given from which lattice parameters a=6.212830 and c=11.0090 were calculated on the basis of the tetragonal crystal system.
Enger, Shirin A; Munck af Rosenschöld, Per; Rezaei, Arash; Lundqvist, Hans
2006-02-01
GEANT4 is a Monte Carlo code originally implemented for high-energy physics applications and is well known for particle transport at high energies. The capacity of GEANT4 to simulate neutron transport in the thermal energy region is not equally well known. The aim of this article is to compare MCNP, a code commonly used in low energy neutron transport calculations and GEANT4 with experimental results and select the suitable code for gadolinium neutron capture applications. To account for the thermal neutron scattering from chemically bound atoms [S(alpha,beta)] in biological materials a comparison of thermal neutron fluence in tissue-like poly(methylmethacrylate) phantom is made with MCNP4B, GEANT4 6.0 patch1, and measurements from the neutron capture therapy (NCT) facility at the Studsvik, Sweden. The fluence measurements agreed with MCNP calculated results considering S(alpha,beta). The location of the thermal neutron peak calculated with MCNP without S(alpha,beta) and GEANT4 is shifted by about 0.5 cm towards a shallower depth and is 25%-30% lower in amplitude. Dose distribution from the gadolinium neutron capture reaction is then simulated by MCNP and compared with measured data. The simulations made by MCNP agree well with experimental results. As long as thermal neutron scattering from chemically bound atoms are not included in GEANT4 it is not suitable for NCT applications.
Løken, Andreas; Haugsrud, Reidar; Bjørheim, Tor S
2016-11-16
Differentiating chemical and thermal expansion is virtually impossible to achieve experimentally. While thermal expansion stems from a softening of the phonon spectra, chemical expansion depends on the chemical composition of the material. In the present contribution, we, for the first time, completely decouple thermal and chemical expansion through first principles phonon calculations on BaCeO3, providing new fundamental insights to lattice expansion. We assess the influence of defects on thermal expansion, and how this in turn affects the interpretation of chemical expansion and defect thermodynamics. The calculations reveal that the linear thermal expansion coefficient is lowered by the introduction of oxygen vacancies being 10.6 × 10(-6) K(-1) at 300 K relative to 12.2 × 10(-6) K(-1) for both the protonated and defect-free bulk lattice. We further demonstrate that the chemical expansion coefficient upon hydration varies with temperature, ranging from 0.070 to 0.115 per mole oxygen vacancy. Ultimately, we find that, due to differences in the thermal expansion coefficients under dry and wet conditions, the chemical expansion coefficients determined experimentally are grossly underestimated - around 55% lower in the case of 10 mol% acceptor doped BaCeO3. Lastly, we evaluate the effect of these volume changes on the vibrational thermodynamics.
NASA Astrophysics Data System (ADS)
Busi, Sara; Lahtinen, Manu; Kärnä, Minna; Valkonen, Jussi; Kolehmainen, Erkki; Rissanen, Kari
2006-04-01
Nine RR2'NCl (R=benzyl, 2-methylbenzyl, 3-methylbenzyl, 4-methylbenzyl, 2-phenylethyl or 3-phenylpropyl; R'=ethyl or methyl) quaternary dialkyldiaralkylammonium chlorides were synthesized by treating dimethylformamide or diethylformamide with non-substituted or substituted arylalkyl (aralkyl) halide in the presence of sodium carbonate. The 1H NMR, 13C NMR spectroscopy, mass spectroscopy and elemental analysis were used to characterize the synthesized products. The crystal structures of six compounds were determined by X-ray single crystal diffraction. Four of the compounds crystallized in monoclinic space groups C2/ c and P2 1/ c (or P2 1/ n), one in triclinic space group P-1 and one in orthorhombic space group Pbca. The powder diffraction method was used to compare the structural similarities between the single crystal and the microcrystalline bulk composition. Thermal properties of the new compounds were studied using TG/DTA and DSC methods. The decomposition of the compounds started generally between 130-185 °C and occurred without identifiable cleavages. The synthesized compounds do not seem to be suitable for ionic liquid applications because no melting point was observed for most of them. However, the good thermal stability of these compounds enables their potential use for example as phase-transfer catalysts and electrolytes.
Structure and thermal properties of yttrium alumino-phosphate glasses.
Martin, Richard A; Salmon, Philip S; Carroll, Donna L; Smith, Mark E; Hannon, Alex C
2008-03-19
The structure and thermal properties of yttrium alumino-phosphate glasses, of nominal composition (Y(2)O(3))(0.31-z)(Al(2)O(3))(z)(P(2)O(5))(0.69) with [Formula: see text], were studied by using a combination of neutron diffraction, (27)Al and (31)P magic angle spinning nuclear magnetic resonance, differential scanning calorimetry and thermal gravimetric analysis methods. The Vickers hardness of the glasses was also measured. The data are compared to those obtained for pseudo-binary Al(2)O(3)-P(2)O(5) glasses and the structure of all these materials is rationalized in terms of a generic model for vitreous phosphate materials in which Y(3+) and Al(3+) act as modifying cations that bind only to the terminal (non-bridging) oxygen atoms of PO(4) tetrahedra. The results are used to help elucidate the phenomenon of rare-earth clustering in phosphate glasses which can be reduced by substituting Al(3+) ions for rare-earth R(3+) ions at fixed modifier content.
Water retention curves and thermal insulating properties of Thermosand
NASA Astrophysics Data System (ADS)
Leibniz, Otto; Winkler, Gerfried; Birk, Steffen
2010-05-01
The heat loss and the efficiency of isolating material surrounding heat supply pipes are essential issues for the energy budget of heat supply pipe lines. Until now heat loss from the pipe is minimized by enlarging the polyurethane (PU) - insulation thickness around the pipe. As a new approach to minimize the heat loss a thermally insulating bedding material was developed and investigated. Conventional bedding sands cover all necessary soil mechanical properties, but have a high thermal conductivity from λ =1,5 to 1,7 W/(m K). A newly developed embedding material 'Thermosand' shows thermal properties from λ=0,18 W/(m K) (dry) up to 0,88 W/(m K) (wet). The raw material originates from the waste rock stockpiles of a coal mine near Fohnsdorf, Austria. With high temperatures up to nearly 1000 ° C and a special mineral mixture, a natural burned reddish material resembling clinker arises. The soilmechanical properties of Thermosand has been thoroughly investigated with laboratory testing and in situ investigations to determine compaction-, permeability- and shear-behaviour, stiffness and corresponding physical parameters. Test trenches along operational heat pipes with temperature-measurement along several cross-sections were constructed to compare conventional embedding materials with 'Thermosand'. To investigate the influence of varying moisture content on thermal conductivity a 1:1 large scale model test in the laboratory to simulate real insitu-conditions was established. Based on this model it is planned to develop numerical simulations concerning varying moisture contents and unsaturated soil mechanics with heat propagation, including the drying out of the soil during heat input. These simulations require the knowledge about the water retention properties of the material. Thus, water retention curves were measured using both steady-state tension and pressure techniques and the simplified evaporation method. The steady-state method employs a tension table (sand
Structure and properties of electronic and hole centers in CsBr from theoretical calculations
Halliday, Matthew T.; Hess, Wayne P.; Shluger, Alexander L.
2015-06-24
The electronic structure, geometry, diffusion barriers and optical properties of fundamental defects of CsBr are calculated using hybrid functional DFT and TD- DFT methods. The B3LYP functional with a modified exchange contribution has been used in an embedded cluster scheme to model the structure and spectroscopic properties of self-trapped triplet exciton, interstitial Br atoms and ions, self-trapped holes and Br vacancies. The calculated migration barriers and positions of maxima of optical absorption bands are in good agreement with experiment, justifying the obtained defect geometries. The o*-center triplet exciton luminescence energy is also accurately calculated.
Computer program for calculating hydrodynamic properties of shock waves in sea water
NASA Astrophysics Data System (ADS)
Fuhs, A. E.
1982-02-01
J. M. Richardson, A. B. Arons, and R. R. Halverson developed a calculation procedure for determining the hydrodynamic properties of sea water at the front of a shock wave. The procedure has been programmed for the HP41CV, which is a hand-held programmable calculator. The program, which uses 374 lines of code, reproduces the values for a shock wave as tabulated by Richardson, et al. The advantage of the HP41CV program is that properties can be calculated without use of tables.
NASA Astrophysics Data System (ADS)
Bird, Rebecca A.; Read, Mark S. D.
2017-02-01
A new potential has been derived for ceria and used to calculate its lattice and defect properties. The Ce4+ ⋯O2- potential is obtained via a combination of empirical fitting to crystal structural data and parametric fitting to additional physical properties, while the O2- ⋯O2- potential is transferred from earlier publications on UO2 and PuO2 . The overall potential is subsequently verified and validated by calculation of elastic and dielectric constants, whose values agree favourably with those measured experimentally. The potential is then employed to calculate intrinsic defect formation energies and predict the most favourable type of intrinsic disorder.
NASA Astrophysics Data System (ADS)
Hassaneen, Khaled; Mansour, Hesham
2017-02-01
The single-particle potentials and other properties at absolute zero temperature in isospin asymmetric nuclear matter are investigated in the frame of an extended Brueckner theory. Also thermal quantities are calculated in asymmetric nuclear matter using CD-Bonn potential and the Urbana three-body forces (3BF). Also, the effects of the hole-hole contributions are investigated within the self-consistent Greens function approach. The inclusion of 3BF or the hole-hole contributions improves the predicted saturation property of symmetric nuclear matter within the Brueckner-Hartree-Fock approach and it leads to a significant stiffening of the density dependence of symmetry energy at high densities but the exact saturation point is not reproduced. This is of great importance in astrophysical calculation. A phenomenological term simulating the three-body interaction is introduced to assure the empirical saturation property. The hot properties of asymmetric nuclear matter such as the internal energy and the pressure are analyzed using T2-approximation method at low temperatures.
Liang, Xin M; Ding, Weiping; Chen, Hsiu-hung; Shu, Zhiquan; Zhao, Gang; Zhang, Hai-feng; Gao, Dayong
2011-10-01
Obtaining accurate thermal properties of biomaterials plays an important role in the field of cryobiology. Currently, thermal needle, which is constructed by enclosing a manually winded thin metal wire with an insulation coating in a metallic sheath, is the only available device that is capable of measuring thermal conductivity of biomaterials. Major drawbacks, such as macroscale sensor size, lack of versatile format to accommodate samples with various shapes and sizes, neglected effects of heat transfer inside the probe and thermal contact resistance between the sensing element and the probe body, difficult to mass produce, poor data repeatability and reliability and labor-intense sensor calibration, have significantly reduced their potential to be an essential measurement tool to provide key thermal property information of biological specimens. In this study, we describe the development of an approach to measure thermal conductivity of liquids and soft bio-tissues using a proof-of-concept MEMS based thermal probe. By employing a microfabricated closely-packed gold wire to function as the heater and the thermistor, the presented thermal sensor can be used to measure thermal conductivities of fluids and natural soft biomaterials (particularly, the sensor may be directly inserted into soft tissues in living animal/plant bodies or into tissues isolated from the animal/plant bodies), where other more standard approaches cannot be used. Thermal standard materials have been used to calibrate two randomly selected thermal probes at room temperature. Variation between the obtained system calibration constants is less than 10%. By incorporating the previously obtained system calibration constant, three randomly selected thermal probes have been successfully utilized to measure the thermal conductivities of various solutions and tissue samples under different temperatures. Overall, the measurements are in agreement with the recommended values (percentage error less than 5
NASA Astrophysics Data System (ADS)
Shenogina, Natalia; Tsige, Mesfin; Mukhopadhyay, Sharmila; Patnaik, Soumya
2012-02-01
We use all-atom molecular dynamics (MD) simulations to predict the mechanical and thermal properties of thermosetting polymers. Atomistic simulation is a promising tool which can provide detailed structure-property relationships of densely cross-linked polymer networks. In this work we study the thermo-mechanical properties of thermosetting polymers based on amine curing agents and epoxy resins and have focused on the DGEBA/DETDA epoxy system. At first we describe the modeling approach to construction of realistic all-atom models of densely cross-linked polymer matrices. Subsequently, a series of atomistic simulations was carried out to examine the simulation cell size effect as well as the role of cross-linking density and chain length of the resin strands on thermo-mechanical properties at different temperatures. Two different methods were used to deform the polymer networks. Both static and dynamic approaches to calculating the mechanical properties were considered and the thermo-mechanical properties obtained from our simulations were found in reasonable agreement with experimental values.
NASA Astrophysics Data System (ADS)
Li, Ting; Tang, Zhenan; Huang, Zhengxing; Yu, Jun
2017-01-01
Carbon nanotubes (CNTs) are semimetallic while boron nitride nanotubes (BNNTs) are wide band gap insulators. Despite the discrepancy in their electrical properties, a comparison between the mechanical and thermal properties of CNTs and BNNTs has a significant research value for their potential applications. In this work, molecular dynamics simulations are performed to systematically investigate the mechanical and thermal properties of CNTs and BNNTs. The calculated Young's modulus is about 1.1 TPa for CNTs and 0.72 TPa for BNNTs under axial compressions. The critical bucking strain and maximum stress are inversely proportional to both diameter and length-diameter ratio and CNTs are identified axially stiffer than BNNTs. Thermal conductivities of (10, 0) CNTs and (10, 0) BNNTs follow similar trends with respect to length and temperature and are lower than that of their two-dimensional counterparts, graphene nanoribbons (GNRs) and BN nanoribbons (BNNRs), respectively. As the temperature falls below 200 K (130 K) the thermal conductivity of BNNTs (BNNRs) is larger than that of CNTs (GNRs), while at higher temperature it is lower than the latter. In addition, thermal conductivities of a (10, 0) CNT and a (10, 0) BNNT are further studied and analyzed under various axial compressive strains. Low-frequency phonons which mainly come from flexure modes are believed to make dominant contribution to the thermal conductivity of CNTs and BNNTs.
Thermophysical Properties of Selected Aerospace Materials. Part 1. Thermal Radiative Properties
1976-01-01
aluminum alloys —stainless steels—titanium alloys — manganese steel— aluminum oxide—boron nitride—calcium aluminum ...Johnson ( Aluminum Alloy 2024), Dr. P. D. Desai ( Aluminum Alloy 7075 and Titanium Alloy Ti-6A1-4V), Mr. T. Y. R. Lee (AISI 304 Stainless Steel), Dr. R...RECOMMENDED VALUES . 24 4. THERMAL RADIATIVE PROPERTIES OF SELECTEP MATERIALS ... 26 4.1. Aluminum Alloy 2024 27 M. W. Johnson 4.2. Aluminum
EFFECT OF HEAT TREATMENT ON THERMAL PROPERTIES OF PITCH-BASED AND PAN-BASED CARBON-CARBON COMPOSITES
Iqbal, Sardar S.; Dinwiddie, Ralph Barton; Porter, Wallace D; Lance, Michael J; Fillip, Peter
2011-01-01
Thermal properties of two directional (2D) pitch-based carbon fiber with charred resin and three directional (3D) PAN-based carbon fiber with CVI carbon matrix C/C composite were investigated for non-heat treated (NHT) and heat treated (HT) materials through the thickness (z-direction). Heat treatment was performed at 1800, 2100 and 2400 oC for 1-hr in inert argon atmosphere. Thermal diffusivity, heat capacity and bulk density were measured to calculate thermal conductivity. Thermal diffusivity and conductivity was the highest for 3D C/C heat treated at maximum temperature with non-heat treated one exhibiting the lowest one. Similarly, 2D C/C heat treated at maximum temperature exhibited the highest thermal diffusivity and thermal conductivity. Polarized light microscopy (PLM) images of HTT C/C show a progressive improvement in microstructure when compared to NHT C/C. However, HTT 2D and 3D C/C composites exhibited extensive shrinkage of charred resin and CVI carbon matrix, respectively, from fibers resulting in intra and inter-bundles cracking when compared to NHT one. Raman spectroscopy and XRD results of NHT and HTT C/C indicated increased ordering of structure. A progressive improvement in thermal properties was observed with increased heat treatment temperatures.
Muraoka, Michihiro; Susuki, Naoko; Yamaguchi, Hiroko; Tsuji, Tomoya; Yamamoto, Yoshitaka
2016-03-21
Methane hydrates (MHs) are present in large amounts in the ocean floor and permafrost regions. Methane and hydrogen hydrates are being studied as future energy resources and energy storage media. To develop a method for gas production from natural MH-bearing sediments and hydrate-based technologies, it is imperative to understand the thermal properties of gas hydrates. The thermal properties' measurements of samples comprising sand, water, methane, and MH are difficult because the melting heat of MH may affect the measurements. To solve this problem, we performed thermal properties' measurements at supercooled conditions during MH formation. The measurement protocol, calculation method of the saturation change, and tips for thermal constants' analysis of the sample using transient plane source techniques are described here. The effect of the formation heat of MH on measurement is very small because the gas hydrate formation rate is very slow. This measurement method can be applied to the thermal properties of the gas hydrate-water-guest gas system, which contains hydrogen, CO2, and ozone hydrates, because the characteristic low formation rate of gas hydrate is not unique to MH. The key point of this method is the low rate of phase transition of the target material. Hence, this method may be applied to other materials having low phase-transition rates.
Correlation of physical properties of ceramic materials with resistance to fracture by thermal shock
NASA Technical Reports Server (NTRS)
Lidman, W G; Bobrowsky, A R
1949-01-01
An analysis is made to determine which properties of materials affect their resistance to fracture by thermal stresses.From this analysis, a parameter is evaluated that is correlated with the resistance of ceramic materials to fracture by thermal shock as experimentally determined. This parameter may be used to predict qualitatively the resistance of a material to fracture by thermal shock. Resistance to fracture by thermal shock is shown to be dependent upon the following material properties: thermal conductivity, tensile strength, thermal expansion, and ductility modulus. For qualitative prediction of resistance of materials to fracture by thermal shock, the parameter may be expressed as the product of thermal conductivity and tensile strength divided by the product of linear coefficient of thermal expansion and ductility modulus of the specimen.
The MD simulation of thermal properties of plutonium dioxide
NASA Astrophysics Data System (ADS)
Mingjie, Wan; Li, Zhang; Jiguang, Du; Duohui, Huang; Lili, Wang; Gang, Jiang
2012-12-01
The thermodynamic properties of PuO2 have been investigated between 300 and 3000 K by molecular dynamics (MD) simulation with empirical interaction potential. The properties include melting point, lattice parameter variation, enthalpy and heat capacity. The melting point of two-phase simulation (TPS) is in agreement with the experimental value, and it gives a much lower value than one-phase simulation (OPS). The lattice parameter and heat capacity at high temperatures are expressed as a(T)=5.38178+4.38×10-5T+6.5525×10-9T+0.9362×10-12T and CP(KJṡmol-1ṡK-1)=18648.8e/(T(-1)2)+9.337×10-6T, respectively. True linear thermal expansion coefficient (TLTEC) α is about 8.89×10-6 K-1 at 300 K. Our simulation results are in good agreement with experimental and other theoretical data.
Optical properties of mineral dust aerosol in the thermal infrared
NASA Astrophysics Data System (ADS)
Köhler, Claas H.
2017-02-01
The optical properties of mineral dust and biomass burning aerosol in the thermal infrared (TIR) are examined by means of Fourier Transform Infrared Spectrometer (FTIR) measurements and radiative transfer (RT) simulations. The measurements were conducted within the scope of the Saharan Mineral Dust Experiment 2 (SAMUM-2) at Praia (Cape Verde) in January and February 2008. The aerosol radiative effect in the TIR atmospheric window region 800-1200 cm-1 (8-12 µm) is discussed in two case studies. The first case study employs a combination of IASI measurements and RT simulations to investigate a lofted optically thin biomass burning layer with emphasis on its potential influence on sea surface temperature (SST) retrieval. The second case study uses ground based measurements to establish the importance of particle shape and refractive index for benchmark RT simulations of dust optical properties in the TIR domain. Our research confirms earlier studies suggesting that spheroidal model particles lead to a significantly improved agreement between RT simulations and measurements compared to spheres. However, room for improvement remains, as the uncertainty originating from the refractive index data for many aerosol constituents prohibits more conclusive results.
Magnetic colloid by PLA: Optical, magnetic and thermal transport properties
NASA Astrophysics Data System (ADS)
Pandey, B. K.; Shahi, A. K.; Gopal, Ram
2015-08-01
Ferrofluids of cobalt and cobalt oxide nanoparticles (NPs) have been successfully synthesized using liquid phase-pulse laser ablation (LP-PLA) in ethanol and double distilled water, respectively. The mechanism of laser ablation in liquid media and formation process for Co target in double distilled water (DDW) and ethanol are speculated based on the reactions between laser generated highly nascent cobalt species and vaporized solvent media in a confined high temperature and pressure at the plume-surrounding liquid interface region. Optical absorption, emission, vibrational and rotational properties have been investigated using UV-vis absorption, photoluminescence (PL) and Fourier transform-infra red (FT-IR) spectroscopy, respectively. In this study optical band gap of cobalt oxide ferrofluids has been engineered using different pulse energy of Nd:YAG laser in the range of (2.80-3.60 eV). Vibrating sample magnetometer (VSM) is employed to determine the magnetic properties of ferrofluids of cobalt and cobalt oxide NPs while their thermal conductivities are examined using rotating disc method. Ferrofluids have gained enormous curiosity due to many technological applications, i.e. drug delivery, coolant and heating purposes.
NASA Astrophysics Data System (ADS)
Benmadani, Y.; Kermaoui, A.; Chalal, M.; Khemici, W.; Kellou, A.; Pellé, F.
2013-10-01
The influence of composition on the thermal stability of tellurite glasses was investigated by using differential scanning calorimetry (DSC). The studied glasses were synthesized by conventional melting quenching method. The best thermal stability and poor crystallization tendency were obtained for the glass composed of 65TeO2-15ZnO-10Na2O-5BaO-3La2O3 doped with Er2O3 (2 mol %). This glass will be referred, in this article, as TZNBL: Er3+ glass. The spectroscopic properties of the above glass are investigated based on the Judd-Ofelt and McCumber theories. The calculated intensity parameters (Ω2,4,6) are compared to those obtained for Er3+ in other glasses. The radiative emission rate has been calculated for the different Er3+emitting levels. The high values of Ω4 and Ω6 confirm the results of the DSC experiment concerning the rigidity of the studied glass. Absorption, emission and gain cross section of the 4I13/2 ↔ 4I15/2 (Er3+) transition in the studied glass are reported and the results are compared to those of other glasses. The 4I13/2 ↔ 4I15/2 (Er3+) absorption and emission cross sections derived by the application of the Mc Cumber's theory corroborate the Judd-Ofelt results. The whole of results demonstrate that the new composition leads to good thermal and mechanical properties as well efficient Er3+ absorption, emission cross sections, which make this glass as a promising candidate for laser action and amplification.
NASA Astrophysics Data System (ADS)
Haire, Melissa A.; Vargo, David D.
2007-01-01
The selected configuration for the Project Prometheus Space Nuclear Power Plant was a direct coupling of Brayton energy conversion loop(s) to a single reactor heat source through the gas coolant/working fluid. A mixture of helium (He) and xenon (Xe) gas was assumed as the coolant/working fluid. Helium has superior thermal conductivity while xenon is added to increase the gas atomic weight to benefit turbomachinery design. Both elements have the advantage of being non-reactive. HeXe transport properties (viscosity and thermal conductivity) were needed to calculate pressure drops and heat transfer rates. HeXe mixture data are limited, necessitating the use of semi-empirical correlations to calculate mixture properties. Several approaches are available. Pure component properties are generally required in the mixture calculations. While analytical methods are available to estimate pure component properties, adequate helium and xenon pure component data are available. This paper compares the sources of pure component data and the approaches to calculate mixture properties. Calculated mixture properties are compared to the limited mixture data and approaches are recommended to calculate both pure component and mixture properties. Given the limited quantity of HeXe mixture data (all at one atmosphere), additional testing may have been required for Project Prometheus to augment the existing data and confirm the selection of mixture property calculation methods.
Haire, Melissa A.; Vargo, David D.
2007-01-30
The selected configuration for the Project Prometheus Space Nuclear Power Plant was a direct coupling of Brayton energy conversion loop(s) to a single reactor heat source through the gas coolant/working fluid. A mixture of helium (He) and xenon (Xe) gas was assumed as the coolant/working fluid. Helium has superior thermal conductivity while xenon is added to increase the gas atomic weight to benefit turbomachinery design. Both elements have the advantage of being non-reactive. HeXe transport properties (viscosity and thermal conductivity) were needed to calculate pressure drops and heat transfer rates. HeXe mixture data are limited, necessitating the use of semi-empirical correlations to calculate mixture properties. Several approaches are available. Pure component properties are generally required in the mixture calculations. While analytical methods are available to estimate pure component properties, adequate helium and xenon pure component data are available. This paper compares the sources of pure component data and the approaches to calculate mixture properties. Calculated mixture properties are compared to the limited mixture data and approaches are recommended to calculate both pure component and mixture properties. Given the limited quantity of HeXe mixture data (all at one atmosphere), additional testing may have been required for Project Prometheus to augment the existing data and confirm the selection of mixture property calculation methods.
Nimick, F.B.; Schwartz, B.M.
1987-09-01
Experimental data on matrix porosity, grain density, thermal expansion, compressive strength, Young`s modulus, Poisson`s ratio, and axial strain at failure for samples from the Topopah Spring Member of the Paintbrush Tuff are compiled. Heat capacity and emissivity also are discussed. Data have been analyzed for spatial variability; slight variability is observed for matrix porosity, grain density, and thermal expansion coefficient. Estimates of in situ values for some properties, such as bulk density and heat capacity, are presented. Vertical in situ stress as a function of horizontal and vertical location has been calculated. 96 refs., 37 figs., 27 tabs.
NASA Astrophysics Data System (ADS)
Wu, Wenxia; Xue, Zhiyong; Hong, Xing; Li, Xiumei; Guo, Yongquan
2009-06-01
The valence electronic structures of Fe, Co and Ni have been investigated with Empirical Electron Theory of Solids and Molecules. The magnetic moments, Curie temperature, cohesive energy and melting point have been calculated according to the valence electronic structure. These calculations fit the experimental data very well. Based on the calculations, the magnetic moments are proportional to the number of 3d magnetic electrons. Curie temperatures are related to the magnetic electrons and the bond lengths between magnetic atoms. Cohesive energies increase with the increase of the number of covalent electrons, and the decrease of the number of magnetic and dumb pair electrons. The melting point is mainly related to the number of covalent electron pairs distributed in the strongest bond. The contribution from the lattice electrons is very small, the dumb pair electrons weaken the melting point; however, the contribution to melting point of the magnetic electrons can be neglected. It reveals that the magnetic and thermal properties are closely related to the valence electronic structures, and the changes or transitions between the electrons obviously affect the physical properties.
NASA Astrophysics Data System (ADS)
Wei, Yong-Kai; Ge, Ni-Na; Ji, Guang-Fu; Chen, Xiang-Rong; Cai, Ling-Cang; Zhou, Su-Qin; Wei, Dong-Qing
2013-09-01
The lattice dynamic, elastic, superconducting, and thermodynamic properties of the high-pressure cubic metallic phase AlH3 are studied within density function theory. The calculated elastic modulus and phonon dispersion curves at various pressures indicate that the cubic phase is both mechanically and dynamically stable above 73 GPa. The superconducting transition temperature was calculated using Allen-Dynes modification of the McMillan formula based on the Bardeen-Cooper-Schrieffer theory. It is found that Tc approaches a linear decrease in the low pressure range at the rate dTC/dP ≈-0.22 K/GPa but gradually decreases exponentially at higher pressure, and then it becomes 0 K upon further compression. The calculations indicate that Tc is about 2.042 K at 110 GPa, in agreement with experimental results. The soft phonon modes, especially the lowest acoustic mode, contribute almost 79% to the total electron-phonon coupling parameter sλ for cubic AlH3 at 73 GPa. However, they disappear gradually with increasing pressure, showing a responsibility for the variation of Tc. The thermodynamic properties of cubic AlH3, such as the dependence of thermal expansion coefficient αV on pressure and temperature, the specific heat capacity CP, as well as the electronic specific heat coefficient Cel, were also investigated by the quasi-harmonic approximation theory.
Determination of the thermal properties of leaves by non-invasive contact‑free laser probing.
Buyel, J F; Gruchow, H M; Tödter, N; Wehner, M
2016-01-10
The thermal properties of materials provide valuable data for quality monitoring and the rational design of process steps where heating is required. Here we report a rapid, simple and reliable technique that determines the most important thermal properties of leaves, i.e. the specific heat capacity (cp) and thermal conductivity (λ). Such data are useful when leaves are heated during processing, e.g. for the precipitation of host cell proteins during the extraction of high-value products such as recombinant proteins produced by molecular farming. The cp of tobacco (Nicotiana tabacum) and Nicotiana benthamiana leaves was determined by infrared measurement of the temperature increase caused by a near-infrared laser pulse of defined length and intensity. We used the sample temperature profiles to calculate λ based on exponential fits of the temperature decline, taking convective heat transfer and thermal radiation into account. We found that the average cp was 3661 ± 323 J kg(-1) K(-1) (n=19) for tobacco and 2253 ± 285 J kg(-1) K(-1) (n=25) for N. benthamiana, whereas the average λ was 0.49 ± 0.13 (n=19) for tobacco and 0.41 ± 0.20 (n=25) Jm(-1) s(-1)K(-1) for N. benthamiana. These values are similar to those established for other plant species by photothermal imaging and other methods. The cp and λ values of leaves can be determined easily using our non-invasive method, which is therefore suitable for the in-line or at-line monitoring of plants, e.g. during the highly regulated production of biopharmaceutical proteins.
PHONON DEPENDENCE ON THERMAL PROPERTIES OF RGaO3(R = La, Ce, Nd, Pr, Sm, Gd)
NASA Astrophysics Data System (ADS)
Parveen, Atahar; Gaur, N. K.
2012-03-01
We have systematically investigated the effect of phonons on elastic, thermal and cohesive properties for rare earth gallates RGaO3(R = La, Ce, Nd, Pr, Sm, Gd) by means of a Rigid Ion Model after modifying its framework to incorporate the van der Waals interactions. Besides that, we have calculated the temperature dependence of the specific heat for the present orthogallates. The results on bulk modulus, Debye temperature and specific heat reproduce well with the available experimental data.
NASA Technical Reports Server (NTRS)
Arnold, Steven M.; Murthy, Pappu L.; Bednarcyk, Brett A.; Lawson, John W.; Monk, Joshua D.; Bauschlicher, Charles W., Jr.
2016-01-01
Next generation ablative thermal protection systems are expected to consist of 3D woven composite architectures. It is well known that composites can be tailored to achieve desired mechanical and thermal properties in various directions and thus can be made fit-for-purpose if the proper combination of constituent materials and microstructures can be realized. In the present work, the first, multiscale, atomistically-informed, computational analysis of mechanical and thermal properties of a present day - Carbon/Phenolic composite Thermal Protection System (TPS) material is conducted. Model results are compared to measured in-plane and out-of-plane mechanical and thermal properties to validate the computational approach. Results indicate that given sufficient microstructural fidelity, along with lowerscale, constituent properties derived from molecular dynamics simulations, accurate composite level (effective) thermo-elastic properties can be obtained. This suggests that next generation TPS properties can be accurately estimated via atomistically informed multiscale analysis.
NASA Astrophysics Data System (ADS)
Shabbir, Ahmed; Muhammad, Zafar; M, Shakil; M, A. Choudhary
2016-03-01
The structural, electronic, mechanical, and thermal properties of Pt, Pd, Rh, Ir, Os metals and their alloys PtPdX (X = Ir, Os and Rh) are studied systematically using ab initio density functional theory. The groundstate properties such as lattice constant and bulk modulus are calculated to find the equilibrium atomic position for stable alloys. The electronic band structure and density of states are calculated to study the electronic behavior of metals on making their alloys. The electronic properties substantiate the metallic behavior for all studied materials. The firstprinciples density functional perturbation theory as implemented in quasi-harmonic approximation is used for the calculations of thermal properties. We have calculated the thermal properties such as the Debye temperature, vibrational energy, entropy and constant-volume specific heat. The calculated properties are compared with the previously reported experimental and theoretical data for metals and are found to be in good agreement. Calculated results for alloys could not be compared because there is no data available in the literature with such alloy composition.
NASA Astrophysics Data System (ADS)
Tawfik, Abdel Nasser; Diab, Abdel Magied; Hussein, M. T.
2016-11-01
In mean field approximation, the grand canonical potential of SU(3) Polyakov linear-σ model (PLSM) is analyzed for chiral phase transition, σl and σs and for deconfinement order-parameters, ϕ and ϕ∗ of light- and strange-quarks, respectively. Various PLSM parameters are determined from the assumption of global minimization of the real part of the potential. Then, we have calculated the subtracted condensates (Δl,s). All these results are compared with recent lattice QCD simulations. Accordingly, essential PLSM parameters are determined. The modeling of the relaxation time is utilized in estimating the conductivity properties of the QCD matter in thermal medium, namely electric [σel(T)] and heat [κ(T)] conductivities. We found that the PLSM results on the electric conductivity and on the specific heat agree well with the available lattice QCD calculations. Also, we have calculated bulk and shear viscosities normalized to the thermal entropy, ξ/s and η/s, respectively, and compared them with recent lattice QCD. Predictions for (ξ/s)/(σel/T) and (η/s)/(σel/T) are introduced. We conclude that our results on various transport properties show some essential ingredients, that these properties likely come up with, in studying QCD matter in thermal and dense medium.
NASA Astrophysics Data System (ADS)
Gergely, M.; Garrett, T. J.
2015-12-01
Significant progress has been achieved in approximating snowflakes and ice-cloud particles by increasingly more realistic and detailed shape models and in calculating associated scattering properties crucial to snowfall remote sensing. The applied approximations of the snowflake microstructure applied for the scattering calculations, however, are still based on few available field measurement data, often integrated over many individual snow storms, and only include several microstructural properties that cannot fully capture the natural variability during snowfall, e.g. different degrees of riming or aggregate snowflakes formed from more than one distinct ice crystal habit. In this study, (i) the natural variability of key microstructural properties during snowfall is quantified for individual snow storms based on high-resolution multi-view snowflake imaging data collected with the Multi-Angle Snowflake Camera (MASC) at Alta ski area (Alta, UT), and (ii) the corresponding variability in snowflake scattering properties is calculated. In addition to snowflake size, orientation and aspect ratio, 'particle complexity' (specifying snowflake perimeter and brightness variations in the MASC snowflake images) is included in the presented approach, yielding a quantitative and objective measure of characteristic snowflake microstructure, including crystal habit and degree of riming, important for realistically modelling snowfall scattering properties. The aim is to present an analysis of the impact of the observed natural microstructural variability on the derived snowflake scattering properties and ultimately on the snowfall radar reflectivity integrated over the obtained variability of snowflake microstructure and scattering properties.
Development of advanced modal methods for calculating transient thermal and structural response
NASA Technical Reports Server (NTRS)
Camarda, Charles J.
1991-01-01
Higher-order modal methods for predicting thermal and structural response are evaluated. More accurate methods or ones which can significantly reduce the size of complex, transient thermal and structural problems are desirable for analysis and are required for synthesis of real structures subjected to thermal and mechanical loading. A unified method is presented for deriving successively higher-order modal solutions related to previously-developed, lower-order methods such as the mode displacement and mode-acceleration methods. A new method, called the force-derivative method, is used to obtain higher-order modal solutions for both uncoupled (proportionally-damped) structural problems as well as thermal problems and coupled (non-proportionally damped) structural problems. The new method is called the force-derivative method because, analogous to the mode-acceleration method, it produces a term that depends on the forcing function and additional terms that depend on the time derivatives of the forcing function.
Experimental Investigation of Thermal Properties in Glass Fiber Reinforced with Aluminium
NASA Astrophysics Data System (ADS)
Irudaya raja, S. Joseph; Vinod Kumar, T.; Sridhar, R.; Vivek, P.
2017-03-01
A test method of a Guarded heat flow meter are used to measure the thermal conductivity of glass fiber and filled with a aluminum powder epoxy composites using an instrument in accordance with ASTM. This experimental study reveals that the incorporation of aluminum and glass fiber reinforced results in enhancement of thermal conductivity of epoxy resin and thereby improves its heat transfer capability. Fiber metal laminates are good candidates for advanced automobile structural applications due to their high categorical mechanical and thermal properties. The most consequential factor in manufacturing of these laminates is the adhesive bonding between aluminum and FRP layers. Here several glass-fiber reinforced aluminum were laminates with different proportion of bonding adhesion were been manufactured. It was observed that the damage size is more preponderant in laminates with poor interfacial adhesion compared to that of laminates with vigorous adhesion between aluminum and glass layers numerically calculated ones and it is found that the values obtained for various composite models using experimental testing method.
Wang, Liqiong; Chen, Hongyan; Zhang, Tonglai; Zhang, Jianguo; Yang, Li
2007-08-17
Three different substituted potassium salts of trinitrophloroglucinol (H(3)TNPG) were prepared and characterized. The salts are all hydrates, and thermogravimetric analysis (TG) and elemental analysis confirmed that these salts contain crystal H2O and that the amount crystal H2O in potassium salts of H3TNPG is 1.0 hydrate for mono-substituted potassium salts of H3TNPG [K(H2TNPG)] and di-substituted potassium salt of H3TNPG [K2(HTNPG)], and 2.0 hydrate for tri-substituted potassium salt of H3TNPG [K3(TNPG)]. Their thermal decomposition mechanisms and kinetic parameters from 50 to 500 degrees C were studied under a linear heating rate by differential scanning calorimetry (DSC). Their thermal decomposition mechanisms undergo dehydration stage and intensive exothermic decomposition stage. FT-IR and TG studies verify that their final residua of decomposition are potassium cyanide or potassium carbonate. According to the onset temperature of the first exothermic decomposition process of dehydrated salts, the order of the thermal stability from low to high is from K(H2TNPG) and K2(HTNPG) to K3(TNPG), which is conform to the results of apparent activation energy calculated by Kissinger's and Ozawa-Doyle's method. Sensitivity test results showed that potassium salts of H3TNPG demonstrated higher sensitivity properties and had greater explosive probabilities.
Anionic ordering and thermal properties of FeF3·3H2O.
Burbano, Mario; Duttine, Mathieu; Borkiewicz, Olaf; Wattiaux, Alain; Demourgues, Alain; Salanne, Mathieu; Groult, Henri; Dambournet, Damien
2015-10-05
Iron fluoride trihydrate can be used to prepare iron hydroxyfluoride with the hexagonal-tungsten-bronze (HTB) type structure, a potential cathode material for batteries. To understand this phase transformation, a structural description of β-FeF3·3H2O is first performed by means of DFT calculations and Mössbauer spectroscopy. The structure of this compound consists of infinite chains of [FeF6]n and [FeF2(H2O)4]n. The decomposition of FeF3·3H2O induces a collapse and condensation of these chains, which lead to the stabilization, under specific conditions, of a hydroxyfluoride network FeF3-x(OH)x with the HTB structure. The release of H2O and HF was monitored by thermal analysis and physical characterizations during the decomposition of FeF3·3H2O. An average distribution of FeF4(OH)2 distorted octahedra in HTB-FeF3-x(OH)x was obtained subsequent to the thermal hydrolysis/olation of equatorial anionic positions involving F(-) and H2O. This study provides a clear understanding of the structure and thermal properties of FeF3·3H2O, a material that can potentially bridge the recycling of pickling sludge from the steel industry by preparing battery electrodes.
Anionic ordering and thermal properties of FeF3·3H2O
Burbano, Mario; Duttine, Mathieu; Borkiewicz, Olaf; ...
2015-09-17
In this study, iron fluoride tri-hydrate can be used to prepare iron hydroxyfluoride with the Hexagonal-Tungsten-Bronze (HTB) type structure, a potential cathode material for batteries. To understand this phase transformation, a structural description of β-FeF3·3H2O is first performed by means of DFT calculations and Mössbauer spectroscopy. The structure of this compound consists of infinite chains of [FeF6]n and [FeF2(H2O)4]n. The decomposition of FeF3·3H2O induces a collapse and condensation of these chains, which lead to the stabilization, under specific conditions, of a hydroxyfluoride network FeF3-x(OH)x with the HTB structure. The release of H2O and HF was monitored by thermal analysis andmore » physical characterizations during the decomposition of FeF3·3H2O. An average distribution of FeF4(OH)2 distorted octahedra in HTB-FeF3-x(OH)x was obtained subsequent to the thermal hydrolysis/olation of equatorial anionic positions involving F- and H2O. This study provides a clear understanding of the structure and thermal properties of FeF3·3H2O, a material that can potentially bridge the recycling of pickling sludge from the steel industry by preparing battery electrodes.« less
Weese, R K; Burnham, A K
2005-09-28
The properties of pentaamine (5-cyano-2H-tetrazolato-N2) cobalt (III) perchlorate (CP), which was first synthesized in 1968, continues to be of interest for predicting behavior in handling, shipping, aging, and thermal cook-off situations. We report coefficient of thermal expansion (CTE) values over four specific temperature ranges, decomposition kinetics using linear and isothermal heating, and the reaction to three different types of stimuli: impact, spark, and friction. The CTE was measured using a Thermal Mechanical Analyzer (TMA) for samples that were uniaxially compressed at 10,000 psi and analyzed over a dynamic temperature range of -20 C to 70 C. Differential scanning calorimetry, DSC, was used to monitor CP decomposition at linear heating rates of 1-7 C min{sup -1} in perforated pans and of 0.1-1.0 C min{sup -1} in sealed pans. The kinetic triplet was calculated using the LLNL code Kinetics05, and predictions for 210 and 240 C are compared to isothermal thermogravimetric analysis (TGA) experiments. Values are also reported for spark, friction, and impact sensitivity.
NASA Astrophysics Data System (ADS)
Kosaka, Masataka; Monde, Masanori
2015-11-01
For safe and fast fueling of hydrogen in a fuel cell electric vehicle at hydrogen fueling stations, an understanding of the heat transferred from the gas into the tank wall (carbon fiber reinforced plastic (CFRP) material) during hydrogen fueling is necessary. Its thermal properties are needed in estimating heat loss accurately during hydrogen fueling. The CFRP has anisotropic thermal properties, because it consists of an adhesive agent and layers of the CFRP which is wound with a carbon fiber. In this paper, the thermal diffusivity and thermal conductivity of the tank wall material were measured by an inverse solution for one-dimensional unsteady heat conduction. As a result, the thermal diffusivity and thermal conductivity were 2.09 × 10^{-6}{ m}2{\\cdot }{s}^{-1} and 3.06{ W}{\\cdot }{m}{\\cdot }^{-1}{K}^{-1} for the axial direction, while they were 6.03 × 10^{-7} {m}2{\\cdot }{s}^{-1} and 0.93 {W}{\\cdot }{m}^{-1}{\\cdot }{K}^{-1} for the radial direction. The thermal conductivity for the axial direction was about three times higher than that for the radial direction. The thermal diffusivity shows the same trend in both directions because the thermal capacity, ρ c, is independent of direction, where ρ is the density and c is the heat capacity.
Basic knowledge on radiative and transport properties to begin in thermal plasmas modelling
Cressault, Y.
2015-05-15
This paper has for objectives to present the radiative and the transport properties for people beginning in thermal plasmas. The first section will briefly recall the equations defined in numerical models applied to thermal plasmas; the second section will particularly deal with the estimation of radiative losses; the third part will quickly present the thermodynamics properties; and the last part will concern the transport coefficients (thermal conductivity, viscosity and electrical conductivity of the gas or mixtures of gases). We shall conclude the paper with a discussion about the validity of these results the lack of data for some specific applications, and some perspectives concerning these properties for non-equilibrium thermal plasmas.
Calculation of Physicochemical Properties for Short- and Medium-Chain Chlorinated Paraffins
NASA Astrophysics Data System (ADS)
Glüge, Juliane; Bogdal, Christian; Scheringer, Martin; Buser, Andreas M.; Hungerbühler, Konrad
2013-06-01
Short- and medium-chain chlorinated paraffins are potential PBT chemicals (persistent, bioaccumulative, toxic) and short-chain chlorinated paraffins are under review for inclusion in the UNEP Stockholm Convention on Persistent Organic Pollutants. Despite their high production volume of more than one million metric tonnes per year, only few data on their physicochemical properties are available. We calculated subcooled-liquid vapor pressure, subcooled-liquid solubility in water and octanol, Henry's law constant for water and octanol, as well as the octanol-water partition coefficient with the property calculation methods COSMOtherm, SPARC, and EPI Suite™, and compared the results to experimental data from the literature. For all properties, good or very good agreement between calculated and measured data was obtained for COSMOtherm; results from SPARC were in good agreement with the measured data except for subcooled-liquid water solubility, whereas EPI Suite™ showed the largest discrepancies for all properties. After critical evaluation of the three property calculation methods, a final set of recommended property data for short- and medium-chain chlorinated paraffins was derived. The calculated property data show interesting relationships with chlorine content and carbon chain length. Increasing chlorine content does not cause pronounced changes in water solubility and octanol-water partition coefficient (KOW) as long as it is below 55%. Increasing carbon chain length leads to strong increases in KOW and corresponding decreases in subcooled-liquid water solubility. The present data set can be used in further studies to assess the environmental fate and human exposure of this relevant compound class.
La/Sm/Er Cation Doping Induced Thermal Properties of SrTiO3 Perovskite.
Rittiruam, Meena; Seetawan, Tosawat; Yokhasing, Sirakan; Matarat, Korakot; Bach Thang, Phan; Kumar, Manish; Han, Jeon Geon
2016-09-06
The La/Sm/Er cations with different radii doping SrTiO3 (STO) as model Sr0.9R0.1TiO3 (R = La, Sm, Er) were designed to investigate structural characteristics and thermal properties by the molecular dynamics simulation with the Green-Kubo relation at 300-2000 K. The structural characteristics were composed of lattice constant, atoms excursion, and pair correlation function (PCF). The thermal properties consisted of heat capacity and thermal conductivity. The lattice constant of R-doped exhibited less than the STO at 300-1100 K and more than STO at 1500-2000 K, which was encouraged by atom excursion and PCF. The thermal properties was compared with literature data at 300-1100 K. In addition, the thermal properties at 1100-2000 K were predicted. It highlights that thermal conductivity tends to decrease at high temperature, due to perturbation of La, Sm, and Er, respectively.
Turowski, Marcus; Amotchkina, Tatiana; Ehlers, Henrik; Jupé, Marco; Ristau, Detlev
2014-02-01
The electronic and optical properties of TiO2 atomic structures representing simulated thin films have been investigated using density functional theory. Suitable model parameters and system sizes have been identified in advance by validation of the results with experimental data. Dependencies of the electronic band gap and the refractive index have been calculated as a function of film density. The results of the performed calculations have been compared to characterized optical properties of titania single layers deposited using different coating techniques. The modeled dependencies are consistent with experimental observations, and absolute magnitudes of simulated values are in agreement with measured optical data.
NASA Technical Reports Server (NTRS)
Bailey, J. A.; Liao, C. K.
1975-01-01
The thermal properties of paraffin hydrocarbons and hydrocarbon mixtures which may be used as the phase change material (PCM) in thermal capacitors are discussed. The paraffin hydrocarbons selected for consideration are those in the range from C11H24 (n-Undecane) to C20H42 (n-Eicosane). A limited amount of data is included concerning other properties of paraffin hydrocarbons and the thermal and mechanical properties of several aluminum alloys which may find application as constructional materials. Data concerning the melting temperature, transition temperature, latent heat of fusion, heat of transition, specific heat, and thermal conductivity of pure and commercial grades of paraffin hydrocarbons are given. An index of companies capable of producing paraffin hydrocarbons and information concerning the availability of various grades (purity levels) is provided.
Takaki, Hirokazu; Kobayashi, Kazuaki; Shimono, Masato; Kobayashi, Nobuhiko; Hirose, Kenji
2016-01-07
We present the thermoelectric properties of TiN/MgO superlattices employing first-principles calculation techniques. The Seebeck coefficients, the electrical conductances, the thermal conductances, and the figure of merit are investigated employing electrical and thermal transport calculations based on density functional theory combined with the nonequilibrium Green's function and nonequilibrium molecular dynamics simulation methods. The TiN/MgO superlattices with a small lattice mismatch at the interfaces are ideal systems to study the way for an enhancement of thermoelectric properties in artificial nanostructures. We find that the interfacial scattering between the two materials in the metal/insulator superlattices causes the electrical conductance to change rapidly, which enhances the Seebeck coefficient significantly. We show that the figure of merit for the artificial superlattice nanostructures has a much larger value compared with that of the bulk material and changes drastically with the superlattice configurations at the atomistic level.
Waxy soft white wheat: extrusion characteristics and thermal and rheological properties
Technology Transfer Automated Retrieval System (TEKTRAN)
Waxy wheat flour was analyzed for its thermal and rheological properties and extruded to understand its processing characteristics. Comparisons were made with normal soft white wheat flour to identify extrusion differences under the same conditions. The thermal and rheological properties through Rap...
Theoretical Calculations of Refractive Properties for Hg3Te2Cl2 Crystals
NASA Astrophysics Data System (ADS)
Bokotey, O. V.
2016-05-01
This paper reviews the optical properties, such as refractive index, optical dielectric constant, and reflection coefficient of the Hg3Te2Cl2 crystals. The applications of the Hg3X2Y2 crystals as electronic, optical, and optoelectronic devices are very much determined by the nature and magnitude of these fundamental material properties. The origin of chemical bonding in the crystals is very important for definition of the physical and chemical properties. The main structural feature of the Hg3X2Y2 crystals is the presence of covalent pyramids [XHg3] and linear X-Hg-X groups. Optical properties are calculated according to the model proposed by Harrison. The refractive index in the spectral region far from the absorption edge is determined within the generalized single-oscillator model. The calculated results are found to be in good agreement with experimental data.
NASA Astrophysics Data System (ADS)
Ozcelik, Ongun; White, Claire
Using first principle density functional calculations, we present the nanoscale properties of interactions, local bonds, charge distributions, mechanical properties and strength of alkali activated cement phases which are the most promising alternative to the ordinary Portland cement with a much lower cost to the environment. We present results on the stability and long term durability of various alkali activated cement structures, effects of external alkali agents on their properties and ways of utilizing them for further applications. We compare the calculated properties of alkali activated cement with those of ordinary Portland cement and contribute to the formation of long term durability data of these phases. Comparison with X-ray and neutron scattering experiment results are also provided via pair distribution functions extracted from simulation results.
Ab initio calculations of elastic properties of Ru1-xNixAl superalloys
NASA Astrophysics Data System (ADS)
Bleskov, I. D.; Smirnova, E. A.; Vekilov, Yu. Kh.; Korzhavyi, P. A.; Johansson, B.; Katsnelson, M.; Vitos, L.; Abrikosov, I. A.; Isaev, E. I.
2009-04-01
Ab initio total energy calculations based on the exact muffin-tin orbitals method, combined with the coherent potential approximation, have been used to study the thermodynamical and elastic properties of substitutional refractory Ru1-xNixAl alloys. We have found that the elastic constants C' and C11 exhibit pronounced peculiarities near the concentration of about 40 at. % Ni, which we ascribe to electronic topological transitions. Our suggestion is supported by the Fermi surface calculations in the whole concentration range. Results of our calculations show that one can design Ru-Ni-Al alloys substituting Ru by Ni (up to 40 at. %) with almost invariable elastic constants and reduced density.