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  • thermal conductivity  (19)
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  • Springer  (28)
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  • 1
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    Springer
    Letters in mathematical physics 46 (1998), S. 207-218 
    ISSN: 1573-0530
    Keywords: Ising model ; boundary conditions ; Boltzmann weights.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract In this Letter, we analyse the boundary conditions of the planar Ising model and determine the boundary Boltzmann weights in terms of bulk Boltzmann weights. The commutativity of the transfer matrices and their functional relations are shown.
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  • 2
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    Journal of statistical physics 90 (1998), S. 1015-1035 
    ISSN: 1572-9613
    Keywords: Ising model ; mixing conditions ; Basuev region ; boundary conditions ; Glauber dynamics ; exponential relaxation ; spectral gap
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We consider Glauber dynamics on a finite cube in d-dimensional lattice (d≥2), which is associated with basic Ising model at temperature T=1/β≪1 under a magnetic field h 〉 0. We prove that if the “effective magnetic field” is positive, then the relaxation of the Glauber dynamics in the uniform norm is exponentially fast, uniformly over the size of underlying cube. The result covers the case of the free-boundary condition with arbitrarily small positive magnetic field. This paper is a continuation of an attempt initiated earlier by Schonmann and Yoshida to shed more light on the relaxation of the finite-volume Glauber dynamics when the thermodynamic parameter (β, h) is so near the phase transition line, (β, h); β c 〈 β&h = 0, that the Dobrushin–Shlosman mixing condition is no longer available.
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  • 3
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    Journal of statistical physics 90 (1998), S. 211-226 
    ISSN: 1572-9613
    Keywords: Ising model ; stochastic dynamics ; metastability ; nucleation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We investigate metastability in the two dimensional Ising model in a square with free boundary conditions at low temperatures. Starting with all spins down in a small positive magnetic field, we show that the exit from this metastable phase occurs via the nucleation of a critical droplet in one of the four corners of the system. We compute the lifetime of the metastable phase analytically in the limit T → 0, h → 0 and via Monte Carlo simulations at fixed values of T and h and find good agreement. This system models the effects of boundary domains in magnetic storage systems exiting from a metastable phase when a small external field is applied.
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  • 4
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    Journal of statistical physics 90 (1998), S. 1051-1059 
    ISSN: 1572-9613
    Keywords: Ising model ; Peierls contour ; low-temperature expansion ; high dimension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We consider the low-temperature expansion for the Ising model on $$\mathbb{Z}^d ,d \geqslant 2$$ , with ferromagnetic nearest neighbor interactions in terms of Peierls contours. We prove that the expansion converges for all temperatures smaller than Cd(log d)−1, which is the correct order in d.
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  • 5
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    Journal of statistical physics 92 (1998), S. 1203-1208 
    ISSN: 1572-9613
    Keywords: Loop model ; criticality ; universality ; 3–12 lattice ; self-avoiding walk ; connective constant ; Ising model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The partition function of the O(n) loop model on the honeycomb lattice is mapped to that of the O(n) loop model on the 3–12 lattice. Both models share the same operator content and thus critical exponents. The critical points are related via a simple transformation of variables. When n = 0 this gives the recently found exact value μ = 1.711041... for the connective constant of self-avoiding walks on the 3–12 lattice. The exact critical points are recovered for the Ising model on the 3–12 lattice and the dual asanoha lattice at n = 1.
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  • 6
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    Journal of statistical physics 93 (1998), S. 33-78 
    ISSN: 1572-9613
    Keywords: Random external field ; Ising model ; Gibbs states ; ground states ; Bethe lattice ; residual entropy ; dipole configurations ; Griffiths singularities
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The ferromagnetic Ising model on the Bethe lattice of degree k is considered in the presence of a dichotomous external random field ξ x = ±α and the temperature T≥0. We give a description of a part of the phase diagram of this model in the T−α plane, where we are able to construct limiting Gibbs states and ground states. By comparison with the model with a constant external field we show that for all realizations ξ = {ξ x = ±α} of the external random field: (i) the Gibbs state is unique for T 〉 T c (k ≥ 2 and any α) or for α 〉 3 (k = 2 and any T); (ii) the ±-phases coexist in the domain {T 〈 T c, α ≤ H F(T)}, where T c is the critical temperature and H F(T) is the critical external field in the ferromagnetic Ising model on the Bethe lattice with a constant external field. Then we prove that for almost all ξ: (iii) the ±-phases coexist in a larger domain {T 〈 T c, α ≤H F(T) + ε(T)}, where ε(T)〉0; and (iv) the Gibbs state is unique for 3≥α≥2 at any T. We show that the residual entropy at T = 0 is positive for 3≥α≥2, and we give a constructive description of ground states, by so-called dipole configurations.
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  • 7
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    Journal of statistical physics 92 (1998), S. 35-45 
    ISSN: 1572-9613
    Keywords: Competing influences ; Ising model ; Gibbs measures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We continue a study of Schonmann (1994), Schonmann and Shlosman (1996), and Greenwood and Sun (1997) regarding the competing influences of boundary conditions and external field for the Ising model. We find a critical point B 0 in the competing influences for low temperature in dimension d 2A7E; 2.
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  • 8
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    Journal of statistical physics 92 (1998), S. 785-808 
    ISSN: 1572-9613
    Keywords: Critical phenomena ; diluted spin systems ; Ising model ; renormalization group
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Within the massive field-theoretic renormalization-group approach the expressions for the β and γ functions of the anisotropic mn-vector model are obtained for general space dimension d in three-loop approximation. Resumming corresponding asymptotic series, critical exponents for the case of the weakly diluted quenched Ising model (m = 1, n = 0), as well as estimates for the marginal order parameter component number m c of the weakly diluted quenched m-vector model, are calculated as functions of d in the region 2 ≤ d 〈 4. Conclusions concerning the effectiveness of different resummation techniques are drawn.
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  • 9
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    Journal of statistical physics 93 (1998), S. 573-582 
    ISSN: 1572-9613
    Keywords: Scaling ; Ising model ; Markov property ; critical phenomena ; parallel computational procedures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The idea that near the critical point each block of spins behaves just like a single big spin is investigated. The case where a diamond-shaped block of spins is embedded in a (small) sea of spins is studied. Use is made of the Markov property method to make exact computations of the various spin moments needed to test this hypothesis. The residual fluctuation about the mean value of the block spin is seen to tend to a finite fraction of the length of the mean block-spin. This result is in line with previous studies which used different types of boundary conditions.
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  • 10
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    International journal of thermophysics 19 (1998), S. 379-389 
    ISSN: 1572-9567
    Keywords: energy conservation equations ; finite-element method ; high-thermal diffusivity fluids ; low-density measurements ; thermal conductivity ; transient hot-wire
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The measurement of the thermal conductivity of a fluid by means of the transient hot-wire technique so far has made use of an analytical solution of the energy conservation equation for an ideal model, coupled with a set of approximate analytical corrections to account for small departures from the model. For this solution to be valid, constraints were always imposed on the experimental conditions and the construction of the apparatus, resulting in an inability to measure the thermal conductivity of high-thermal diffusivity fluids. In this paper, the set of energy conservation equations describing the transient hot-wire apparatus is solved using the numerical finite-element method. Because no approximate solutions are involved, this provides a much more general treatment of the heat transfer processes taking part in the real experiment, removing all the aforementioned constraints. In the case of the measurement of the thermal conductivity of liquids (fluids with low thermal-diffusivity values), the numerical solution fully agrees with the existing analytical solution. In the case of the measurement of the thermal conductivity of gases, the present solution allows the extension of the application of the transient hot-wire technique to experimental conditions where the value of the thermal diffusivity of the fluid is high.
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  • 11
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    International journal of thermophysics 19 (1998), S. 437-448 
    ISSN: 1572-9567
    Keywords: alkanes ; carbon dioxide ; diffusion ; mixtures ; molecular dynamics ; thermal conductivity ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Equilibrium molecular dynamics simulations of mixtures of n-decane with methane, ethane, and carbon dioxide and of the mixture carbon dioxide–ethane were performed using the anisotropic united atoms model for n-decane and one-and two-center Lennard–Jones models for the light components. The Green–Kubo relations were used to calculate the viscosity, thermal conductivity, and inter- and intradiffusion. Viscosities are predicted with a maximum deviation of 30% at low gas concentrations and less than 10% deviation at high gas concentrations. The viscosity and thermal conductivity are less sensitive to the cross interactions than the diffusion coefficients, which exhibit deviations between models and with experiments of up to 60%.
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  • 12
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    International journal of thermophysics 19 (1998), S. 749-759 
    ISSN: 1572-9567
    Keywords: aqueous solutions ; capillary-rise method ; surface tension ; thermal conductivity ; transient hot-wire method ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Measurements of the surface tension, viscosity, and thermal conductivity of LiBr and LiSCN aqueous binary solutions have been performed to determine the thermophysical properties near the equilibrium freezing temperature. A differential capillary-rise method for surface tension and the transient hot-wire method for thermal conductivity were employed. Furthermore, a rotational viscometer was utilized for the measurement of viscosity. Correlation equations for the data of the aqueous binary test solutions as a function of temperature and concentration are presented.
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  • 13
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    International journal of thermophysics 19 (1998), S. 15-25 
    ISSN: 1572-9567
    Keywords: aqueous solution ; diffraction ; laser-induced thermal grating ; sodium chloride ; thermal conductivity ; thermal diffusivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The laser-induced thermal grating technique was used to determine the thermal diffusivity of aqueous solutions of sodium chloride. In comparison with conventional measurement methods, this noninvasive optical technique has the advantage that no sensors need to be inserted in the sample. Therefore, this technique is especially suitable for the measurement of electrically conducting and corrosive liquids. The aqueous solutions studied have weight fractions of 5, 10, 15, and 20% sodium chloride. Measurement results for the thermal diffusivity are presented for aqueous solutions of sodium chloride in the temperature range 293 to 373 K at atmospheric pressure.
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  • 14
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    International journal of thermophysics 19 (1998), S. 415-425 
    ISSN: 1572-9567
    Keywords: HFC-32 ; HFC-125 ; HFC-134a ; melting point ; refrigerant ; thermal conductivity ; transient hot-wire method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Measurements of the thermal conductivity of HFC-32, HFC-125, and HFC-134a were carried out for the first time in both solid and liquid phases at the saturation pressure at room temperature and in the temperature ranges from 120 to 263, from 140 to 213, and from 130 to 295 K, respectively. A transient hot-wire instrument using one bare platinum wire was employed for measurements, with an uncertainty of less than ±2%. The experimental results demonstrated that the thermal conductivity of HFC-32, HFC-125, and HFC-134a in the solid phase showed a positive temperature dependence. For HFC-32 and HFC-125, there were big jumps between the solid and the liquid thermal conductivity at the melting point. But for HFC-134a, the solid and liquid thermal conductivity at the melting point is almost-continuous.
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  • 15
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    International journal of thermophysics 19 (1998), S. 511-523 
    ISSN: 1572-9567
    Keywords: chemical vapor deposition (CVD) diamond ; phonon scattering ; specific heat ; thermal conductivity ; thermal diffusivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The thermal conductivity κ of natural, gem-quality diamond, which can be as high as 2500 Wm−1 K−1 at 25°C, is the highest of any known material. Synthetic diamond grown by chemical vapor deposition (CVD) of films up to 1 mm thick exhibits generally lower values of κ but under optimal growth conditions it can rival gem-quality diamond with values up to 2200 Wm−1 K−1. However, it is polycrystalline and exhibits a columnar microstructure. Measurements on free-standing CVD diamond, with a thickness in the range 25–400 μm, reveal a strong gradient in thermal conductivity as a function of position z from the substrate surface as well as a pronounced anisotropy with respect to z. The temperature dependence of κ in the range 4 to 400 K has been analyzed to determine the types and numbers of phonon scattering centers as a function of z. The defect structure, and therefore the thermal conductivity, are both correlated with the microstructure. Because of the high conductivity of diamond, these samples are thermally thin. For example, laser flash data for a 25-μm-thick diamond sample is expected to be virtually the same as laser flash data for a 1-μm-thick fused silica sample. Several of the techniques described here for diamond are therefore applicable to much thinner samples of more ordinary material.
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  • 16
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    International journal of thermophysics 19 (1998), S. 615-624 
    ISSN: 1572-9567
    Keywords: photothermal deflection ; thermal conductivity ; thin film
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A three-dimensional theoretical model has been developed to calculate the normal probe beam deflection of the obliquely crossed photothermal deflection configuration in samples which consist of thin films deposited on substrates. Utilizing the dependence of the normal component of probe beam deflection on the cross-point position of the excitation and probe beams, the thermal conductivity of the thin film can be extracted from the ratio of the two maxima of the normal deflection amplitude, which occurs when the cross-point is located near both surfaces of the sample. The effects of other parameters, including the intersect angle between the excitation and the probe beams in the sample, the modulation frequency of the excitation beam, the optical absorption and thickness of the thin films, and the thermal properties of substrates on the thermal conductivity measurement of the thin film, are discussed. The obliquely crossed photothermal deflection technique seems to be well suited for thermal conductivity measurements of thin films with a high thermal conductivity but a low optical absorption, such as diamond and diamond-like carbon, deposited on substrates with a relatively low thermal conductivity.
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  • 17
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    International journal of thermophysics 19 (1998), S. 969-981 
    ISSN: 1572-9567
    Keywords: electrical resistivity ; enthalpy ; high temperature ; liquid alloys ; rhenium alloy ; specific heat ; thermal conductivity ; thermal diffusivity ; tungsten alloy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In earlier experiments we have studied pure elements with a fast pulse heating technique to obtain thermophysical properties of the liquid state. We report here results for thermophysical properties such as specific heat and dependences among enthalpy, electrical resistivity, and temperature, for four W–Re alloys (3.95, 21.03, 23.84, and 30.82 at % of Re) in a wide temperature range covering solid and liquid states. Thermal conductivity is calculated using the Wiedemann–Franz law for the liquid alloy, as.well as data for thermal diffusivity for the beginning of the liquid phase. Additionally, data for the entire temperature range studied have been analyzed in comparison with those of the constituent elements, tungsten and rhenium, since both metals have been studied previously with the same experimental technique. Such information is of interest in the field of metallurgy since W–Re alloys of low Re content in the region of mutual component solubility in the solid state are widely used as thermocouple materials for the purposes of high-temperature thermometry.
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  • 18
    ISSN: 1572-9567
    Keywords: critical state ; electron concentration ; lead ; shock compression ; spectroscopy ; thermal conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Experiments were performed to investigate the behavior of lead near its critical point. Emission spectra of shocked lead samples during unloading into helium at different initial pressures were measured by an optical multichannel analyzer (OMA), as well as by a fast optical pyrometer. To describe the obtained experimental data, a model of a thin mixture layer was suggested, in which helium emits due to the presence of external electrons from lead.
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  • 19
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    International journal of thermophysics 19 (1998), S. 1229-1238 
    ISSN: 1572-9567
    Keywords: food properties ; Peltier effect ; thermal conductivity ; thermoelectric heat pump ; tropical foods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The objective of this work was to test a novel experimental technique to determine the thermal conductivity of low-thermal conductivity materials and tropical foods. The experimental method was based on the Peltier effect and its application to the thermoelectric heat pump. This device became practical recently with the development of semiconductor thermocouple materials. The module assembly used in this work had 127 thermocouples connected in series electrically and in parallel thermally. The heat transfer area of the module was 3.96×3.96 cm2. The equipment was calibrated using standard materials of known thermal conductivity: Plexiglas and Bakelite. Then the κ values were easily computed from a steady-state energy balance equation.
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  • 20
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    International journal of thermophysics 19 (1998), S. 1239-1251 
    ISSN: 1572-9567
    Keywords: criterion of homogeneity ; dispersed composites ; finite element method (FEM) ; laser flash method ; thermal conductivity ; thermal diffusivity ; steady-state comparison method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The effective thermal conductivity of dispersed composites with a hot-melt-adhesive matrix, measured using the steady-state method, is compared with the apparent thermal conductivity calculated from the average heat capacity and from the thermal diffusivity measured by the laser-flash method. The transient effect has been observed obviously at higher volume percentages for various dispersed particle sizes and ratios of the thermal conductivity values of dispersed and continuous phases. All of the experimental results are compared with those calculated by existing models and by the finite element method (FEM). An attempt has been made to show how the criterion for the homogeneity of dispersed composites under transient conditions is affected by the percentages of dispersed phase, dispersed particle size, and ratio of the thermal conductivity values of dispersed and continuous phases.
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  • 21
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    International journal of thermophysics 19 (1998), S. 259-279 
    ISSN: 1572-9567
    Keywords: alumel ; chromel ; constantan ; thermal conductivity ; thermal diffusivity ; transient technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A transient heating technique, improving the constant-rate-heating technique for the measurements of thermal diffusivities of metals, is proposed. For a physical model of a specimen to be measured, the transient heat-conduction equation was solved with some boundary conditions, and the solution obtained was used as the principle of the present transient heating technique for determining the thermal diffusivity of the specimen. Additionally, a thermal analysis was made to satisfy a boundary condition involved in the principle, that is, the condition of radiative thermal insulation at the two end surfaces of the specimen. To verify the validity of the present technique, the thermal diffusivity of iron, whose thermophysical properties are well-known, was measured with the same apparatus as used in our previous work, and the experimental results are discussed. Moreover, thermal diffusivities of thermocouple materials, namely, constantan, chromel, and alumel, were measured by the technique in the temperature range of 360 to 680 K.
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  • 22
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    International journal of thermophysics 19 (1998), S. 281-290 
    ISSN: 1572-9567
    Keywords: GaAs ; impurities ; phonons ; photothermal displacement technique ; semiconductors ; Si ; thermal conductivity ; thermal diffusivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Thermal conductivity and thermal diffusivity of Si and GaAs wafers were measured using the photothermal displacement technique, and the temperature dependence of these two quantities was investigated. Thermal diffusivity was obtained from the phase difference between the heating source and the signal, and thermal conductivity was determined from the maximum value of the signal amplitude in the temperature range 80 to 300 K. It was verified that an increase in doping concentration gives rise to a decrease in thermal conductivity at low temperatures. The experimental results obtained on samples with different types and doping concentrations are consistent with those expected from theoretical considerations.
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  • 23
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    International journal of thermophysics 19 (1998), S. 291-304 
    ISSN: 1572-9567
    Keywords: calorimetry ; emissivity ; high temperature ; specific heat capacity ; thermal conductivity
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    Topics: Physics
    Notes: Abstract Thermal radiation calorimetry has been applied to measure the thermal conductivity and the specific heat capacity of an isolated solid specimen simultaneously. The system, in which a disk-shaped specimen and a flat heater are mounted in a vacuum chamber with the specimen heated on one face by irradiation, is presented. A theoretical formulation of the simultaneous measurement at quasi-steady state is described in detail. Noncontact temperature measurement of both specimen surfaces has been performed using pyrometers and a thermocouple set in the gap between the heater and the specimen. Pyroceram 9609 specimens, whose surfaces were blackened with colloidal graphite, were used in the measurement. The largest error involved in the noncontact temperature measurement is ±2°C in the range from 450 to 650°C. The resultant values of the specific heat capacity and the thermal conductivity deviate by about 10% from the recommended values for the Pyroceram specimen.
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  • 24
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    International journal of thermophysics 19 (1998), S. 931-939 
    ISSN: 1572-9567
    Keywords: adhesives ; coatings ; contact conductance ; thermal barrier coatings ; thermal conductivity ; thermal diffusivity ; thin films
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract There is an intense and growing demand for knowledge of the thermal transport properties and contact conductances of coatings, thin films, and interfaces. The laser flash technique is uniquely suited for many of the measurements. The usefulness and limitations of this technique for coatings, greases, and joining techniques are described in some detail. Several alternate techniques, namely, step heating, multiproperty, and photoacoustic techniques, are briefly examined.
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  • 25
    ISSN: 1572-9567
    Keywords: analytical model ; glass ; laser-flash method ; radiative heat transfer ; thermal conductivity ; thermal diffusivity
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    Topics: Physics
    Notes: Abstract We have developed an analytical model to determine the thermal diffusivity of nonscattering materials from samples with low optical thickness and opaque boundaries with arbitrary emissivities. The paper outlines the new analytical model and describes measurements on two samples: a microscope slide glass and a high-grade fused quartz plate. Results show that the new model applied to measurements on gold- or graphite-coated samples leads to the same results as if a conventional model is used on gold-coated samples.
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  • 26
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    International journal of thermophysics 19 (1998), S. 557-567 
    ISSN: 1572-9567
    Keywords: photothermal method ; scanning laser ; thermal conductivity ; thermal diffusivity ; thermoelectric effect ; thin film
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This work presents a scanning laser-based thermal diffusivity measurement technique for thin films as well as for bulk materials. In this technique, a modulated laser beam is focused through a transparent substrate onto the film–substrate interface. The generated thermal wave is detected using a fast-responding thermocouple formed between the sample surface and the tip of a sharp probe. By scanning the laser beam around the thermocouple, the amplitude and phase distributions of the thermal wave are obtained with micrometer resolution. The thermal diffusivity of the film is determined by fitting the obtained phase signal with a three-dimensional heat conduction model. Experimental results are presented for a 150-nm gold film evaporated on a glass substrate.
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  • 27
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    International journal of thermophysics 19 (1998), S. 595-601 
    ISSN: 1572-9567
    Keywords: liquid crystals ; phase transitions ; photopyroelectric technique ; thermal conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The photopyroelectric technique has been used to measure simultaneously the specific heat, the thermal conductivity, and the thermal diffusivity of 9CB liquid crystal in the temperature range 35 to 60°C, where the sample undergoes a weakly first-order phase transition and a second-order one. Measurements of the anisotropy of the thermal conductivity have also been performed, and the data have been used to establish the order of the above-mentioned phase transitions. Pretransitional effects in the isotropic phase in the thermal diffusivity have been found, and they have been associated with similar effects reported for the specific heat.
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  • 28
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    International journal of thermophysics 19 (1998), S. 1099-1109 
    ISSN: 1572-9567
    Keywords: photoacoustic detector ; thermal conductivity ; thermal diffusivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A resonant and a nonresonant photoacoustic detector were used to determine thermal diffusivities of gases. With a nonresonant detector thermal diffusivities can be determined in a wide range between 10−3 and 10−7 m2·s−1, whereas experiments with the resonant detector deliver thermal diffusivities in a range that is about a factor of 100 smaller. As refrigerants—HFCs, HCFCs, and hydrocarbons—are absorbents in the infrared at a wavelength of 3.39 μm, their thermal diffusivity can be determined without the addition of a trace gas, particularly at pressures below 0.01 MPa. At pressures above 0.1 MPa, the addition of ammonia as a trace gas is recommended. The absorption wavelength is then 1.531 μm. A simulation model for the nonresonant photoacoustic detector is presented for the design of a detector and for an extended error analysis.
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