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Study is presented in which a variety of Green's function solutions are provided for steady-periodic thermal-property techniques in two-dimensional bodies in rectangular coordinates. The solutions provide an opportunity for verification of numerical results by use of distinct, but similar geometries.

Both hydrologic and thermal transport properties play a significant role in the movement of heat through permeable sedimentary material; however, the thermal conductivity is rarely characterized in detailed spatial resolution. As part of a study of the movement of thermal plumes through a sand and gravel aquifer, we have constructed a two-dimensional profile of thermal conductivity. This work consisted of: (i) measuring the thermal conductivity of the soil solids, [[lambda].sub.s], for the main stratigraphic units using the steady-state divided-bar apparatus and estimating conductivity from mineral composition; (ii) measuring the volumetric water content and porosity using crosshole ground-penetrating radar, (iii) evaluating four models used to predict the apparent thermal conductivity, [lambda], of variably saturated soils and selecting the best model using the information-theoretic approach, (iv) calculating the [lambda] field on a 0.25-m square cell grid using measured data and the selected model, and (v) simulating thermal transport within the two-dimensional domain using a finite element numerical model. The apparent thermal conductivity in the saturated aquifer ranges from 2.14 to 2.69 W [m.sup.-1] [K.sup.-1] with a mean of 2.42 W [m.sup.-1] [K.sup.-1]. Numerical simulations show that the heterogeneous thermal conductivity field results in increased thermal dispersion that is most pronounced at the plume front. Our values for [lambda] and [[lambda].sub.s] may be used for glacial soils with similar mineralogy and texture. Our methods may also be used at other sites to construct the thermal conductivity distribution.

Microwave-assisted organic synthesis in nonpolar solvents is investigated utilizing cylinders of sintered silicon carbide SiC, a chemically inert and strongly microwave absorbing material, as passive heating elements PHEs. Microwave energy is absorbed due to this heating, which subsequently transfer the generated thermal energy through conduction phenomena to the reaction mixture.

The enhancement in the effective thermal conductivity of nanofluids is due mainly to the localized convection caused by the Brownian movement of nanoparticles. A convective-conductive is introduced which accurately captures the effects of particle size, choice of base liquid, thermal interfacial resistance between the particles and liquid, temperature.

A model of one-dimensional steady state heat transfer is presented in expanded polystyrene (EPS) foams based on a numerical resolution of the radiation-conduction coupling. Theoretical results are compared to equivalent thermal conductivity measurements made on several EPS foams with the use of a flux-meter apparatus and a good agreement is shown.

Half-Heusler compounds ErPdX (X = Sb and Bi) are prepared by a spark plasma sintering method and their thermoelectric properties at high temperature and thermophysical properties at room temperature are evaluated. The maximum values of the dimensionless figure of merit ZT of ErPdSb and ErPdBi are 0.16 around 699 K and 0.075 at 495 K, respectively.

An experimental investigation is conducted to examine the effects of variations in the temperature and volume fraction on the steady-state effective thermal conductivity of two different nanoparticle suspensions. The results indicate that the nanoparticle material, diameter, volume fraction, and bulk temperature, all have a significant impact on the effective thermal conductivity of these suspensions.

An enhanced laser ablation model is developed, where the laser-induced evaporation is considered, and the rigorous gas-dynamic boundary conditions of condensations are applied. This is model is valid when the phase explosion does not occur, that is when the target surface temperature does not reach or exceed the target material critical temperature.

An optical beam deflection technique for measurements of the thermal diffusivity of fluid mixtures and suspensions of nanoparticles with a precision of better than 1 percent is described. Au nanoparticles are measured to maximum volume fractions of 0.6 percent and 0.35 vol percent.

The fin efficiency of a high-thermal-conductivity substrate coated with a low-thermal-conductivity layer is considered, and an analytical solution is presented and compared to alternative approaches for calculating fin efficiency, by a model, which is appropriate for frost formation on a round-tube-and-fin metallic heat exchanger. However, the analytical solution seems to give rise to an eigenvalue problem with an unusual orthogonality condition.

The Cell Method is an approach to the numerical calculation of fields that has been recently applied to the coupled computation of electric and thermal conduction using a linear interpolation of both the electric and temperature fields. In this paper a quadratic interpolation approach is presented. It is aimed at the achievement of an accurate field distribution computation particularly in complex domains such as biological structures. Such condition are encountered in the prediction of the thermal distribution obtained in hyperthermic treatments. Some results for a real case are presented in the paper. Index Terms--Biomedical applications of electromagnetic field, cell method, finite formulation, hyperthermic treatment, quadratic interpolation.

The size effect on the lattice thermal conductivity of nanoscale wire and multiplayer structures formed in and by some typical semiconductor materials, using the Boltzmann transport equation and focusing on the Knudsen-flow effect is determined. The Knudsen-flow effects are important for almost all types of semiconductor nanostructures but it is found that most of them are pronounced in Si and SiC systems due to the very large phonon mean free paths.

The effect of the superconductivity transition on the thermal crosstalk in YBa(sub 2)Cu(sub 3)O(sub 7-x) edge-transition bolometer arrays is investigated for DC to midrange modulation frequency infrared radiation. One should use modulation frequency greater than the crosstalk-free modulation frequency at the bias temperature for a crosstalk-free bolometer operation.

Power dissipation in electronic devices is projected to increase over the next 10 years to the range of 150-250 W per chip for high performance applications. One of the primary obstacles to the thermal management of devices operating at such high powers is the thermal resistance between the device and the heat spreader or heat sink that it is attached to. Typically the in situ thermal conductivity of interface materials is in the range of 1-4 W/mK, even though the bulk thermal conductivity of the material may be significantly higher. In an attempt to improve the effective in situ thermal conductivity of interface materials nanoparticles and nanotubes are being considered as a possible addition to such interfaces. This paper presents the results of a numerical study of transport in a thermal interface material that is enhanced with carbon nanotubes. The results from the numerical solution are in excellent agreement with an analytical model (Desai, A., Geer, J., and Sammakia, B., 'Models of Steady Heat Conduction in Multiple Cylindrical Domains,' J. Electron. Packaging (to be published)) of the same geometry. Wide ranges of parametric studies were conducted to examine the effects of the thermal conductivity of the different materials, the geometry, and the size of the nanotubes. An estimate of the effective thermal conductivity of the carbon nanotubes was used, obtained from a molecular dynamics analysis (Mahajan, S., Subbarayan, G., Sammakia, B. G., and Jones, W., 2003, Proceedings of the 2003 ASME International Mechanical Engineering Congress and Exposition, Washington, D.C., Nov. 15-21). The numerical analysis was used to estimate the impact of imperfections in the nanotubes upon the overall system performance. Overall the nanotubes are found to significantly improve the thermal performance of the thermal interface material. The results show that varying the diameter of the nanotube and the percentage of area occupied by the nanotubes does not have any significant effect on the total temperature drop. [DOI: 10.1115/1.2161231] Keywords: thermal management, carbon nanotubes, thermal interface material (TIM), numerical modeling, analytical modeling, molecular dynamic simulations

An analytical model of steady state heat conduction in multiple cylindrical domains is presented and discussed. The domains are axisymmetric, contiguous, and coaxial. Three domains are considered in the current study. The thermal conductivities, thicknesses, and radii of the domains may be different. The entire geometry composed of the three connected domains is considered as adiabatic on its lateral surfaces and is subjected to uniform convective cooling at one end. The other end of the geometry is subjected to a constant heat flux, while uniform heat generation is imposed in one of the domains. The analytical solution of the model is found and special cases of it are shown to be in agreement with known solutions for simpler geometries. One application of this model relates to the thermal management of computer chips that are attached to a heat sink or a heat spreader. The three layers could simulate the chip, the thermal adhesive and the heat sink. Another application is the simulation of a nanotube or nanocylinder connecting a region of the chip to a region of the heat sink. Many other potential applications may be simulated using the different possible configurations for the solution presented. [DOI: 10.1115/1.2159003]

We demonstrate in this work and in the accompanying paper that it is possible to measure simultaneously heat capacity and expansibility of biomolecules in a single DSC experiment. In this study, we provide the theoretical basis for this new method based on rigorous statistical thermodynamics. The theoretical treatment presented here demonstrates that there are two additive contributions to the heat capacity at variable pressure, viz. (1) the isobaric heat capacity and (2) an expansibility term, and that these contributions can be experimentally separated to obtain simultaneously both heat capacity and expansibility in continuous DSC temperature scans preformed under pressure modulation. Equations that describe the mixed heat capacity and expansibility signal are derived, and experimental strategies as well as data extraction procedures are discussed.

A new method is described that permits the continuous and synchronous determination of heat capacity and expansibility data. We refer to it as pressure-modulated differential scanning calorimetry (PMDSC), as it involves a standard DSC temperature scan and superimposes on it a pressure modulation of preselected format. The power of the method is demonstrated using salt solutions for which the most accurate heat capacity and expansibility data exist in the literature. As the PMDSC measurements could reproduce the parameters with high accuracy and precision, we applied the method also to an aqueous suspension of multilamellar DSPC vesicles for which no expansibility data had been reported previously for the transition region. Excellent agreement was obtained between data from PMDSC and values from independent direct differential scanning densimetry measurements. The basic theoretical background of the method when using sawtooth-like pressure ramps is given under Supporting Information, and a complete statistical thermodynamic derivation of the general equations is presented in the accompanying paper.

We present a numerical model for calculating the temperature distribution inside resistance-heated high-pressure solid-medium axi-symmetric cell assemblies that incorporates both composition- and temperature-dependent thermal conductivity. The code was validated using both analytic solutions of simplified thermal diffusion problems and comparisons to actual laboratory experiments and was found to be reliable in matching the temperature characteristics of multi-anvil experiments. Calculations for various cell assembly designs resulted in temperature fields that are consistent with experimental measurements of thermal gradients. These calculations also illustrated the influence of temperature-dependence of thermal conductivity, an important and often-overlooked property, on the thermal profiles. This model may be used to fine-tune the design of cell assemblies, either to minimize thermal gradients or to produce a desired temperature distribution. The four 'typical' multi-anvil cells that we used to demonstrate this technique have temperature profiles across the sample that range from 25 to 75 [degrees]C when the thermocouple temperature is 1200 [degrees]C. The thermocouple in all four is in a region where the temperature gradient is on the order of 100 [degrees]C per millimeter, which could lead to experimental temperature uncertainties that are correlated with the thermocouple location. Keywords: Multi-anvil, high pressure, thermal gradients, temperature, numerical modeling

A composite chemical blowing agent PU8, composed of azodiformamide (AC), N,N'-dinitroso pentamethylene tetramine (H) and other chemicals, was used to prepare the poly(propylene carbonate) foam material. The decomposition behavior of the blowing agent was investigated. The effect of blowing agent content and the foaming condition on the foaming of poly(propylene carbonate) was studied in detail. The results suggested that 10 phr PU8 is the optimum formulation to afford a desired poly(propylene carbonate) foam. The morphologies and compression strength of the poly(propylene carbonate) foam were studied using a scanning electron microscope and tensile tester, respectively. The foam with a blowing ratio of 16 can be obtained under an optimum foaming condition at 160°C for 30 min. POLYM. ENG. SCI., 46:153-159, 2006. © 2005 Society of Plastics Engineers, INTRODUCTION As a carbon source, carbon dioxide (C[O.sub.2]) has attracted much attention in both scientific and practical interests in recent years. On the other hand, it is a matter of [...]

A method of controlling multiple frequency test sequences subject to finite temperature tolerance is developed. It is shown that the total control power may be minimized assigning temperature tolerance to the highest frequencies in the test power sequence.

The lateral thermal conductivity of single-crystal silicon layers of thickness 20 and 100 nm at temperature between 30 and 450 K are measured using joule heating and electrical-resistance thermometry in suspended micro fabricated structures. A large reduction in thermal conductivity resulting from phonon-boundary scattering is observed.

A systematic set of experimental data is provided for temperature dependent thermal conductivities of pure and doped silicon layers. Steady-state heating and thermometry in patterned metal bridges are used to measure the thermal conductivity of ultrathin pure and doped silicon layers in the temperature range of 300-450 K.

The effect of surface bond-order loss on the electronic thermal conductivity of metallic polycrystalline films is examined using Boltzmann transport theory. Results show that the thermal conductivity of the films is sensitive to the film thickness, mean grain size, and Fermi energy.

The paper discusses the mechanisms by which inorganic fillers in silicone rubber dielectrics enhance the properties of thermal conductivity, relative permittivity, and electrical conductivity making them useful in outdoor high voltage insulation applications. The addition of alumina trihydrate or silica fillers to silicone elastomers, forming binary composites with enhanced thermal conductivity, is discussed in relation to filler type, particle size, shape, and concentration, and its use as a housing material for non-ceramic insulators to minimize material erosion at dry band arcing sites by lowering hot spot temperature. Also discussed is the enhanced relative permittivity of silicone dielectrics that is obtained through the addition of barium titanate powder which can be further increased with the addition of aluminium powder forming a tertiary composite, resulting in a significant grading of the surface electric field when applied as a housing material to high voltage bushings. Controlled electrical conductivity of silicone dielectrics is discussed through the use of antimony-doped tin oxide filler binary composites and when applied as a housing material to outdoor bushings, the pollution performance is greatly enhanced. Index Terms--Silicone composites, thermal conductivity, relative permittivity, electrical conductivity, outdoor insulation, inorganic fillers.

A review of the best-available data for calculating a complete set of binary collision integral data for the computation of the mixture transport properties (viscosity, thermal conductivity, and ordinary and thermal diffusion) of 13-species weakly ionized air is presented. Although the fidelity of the data varies, all collision integrals presented herein, except fur electron-neutral interactions, are estimated to be accurate to within 25% over the temperature range of interest (300-15,000 K) for reentry and laboratory plasmas. In addition, most of the dominant atom-atom and atom-ion interactions for dissociated weakly ionized air were derived from ab initio methods that are estimated to be accurate to within 10%. The accuracy and valid temperature range for electron-neutral interactions vary because of scarcity of the required cross-sectional data.

The use of ionic liquids (ILs) as a solvent for thermal lens measurements has been investigated. It was found that ILs provide a better medium for thermal lens measurements than water. Specifically, not only the ILs offer at least 20 times higher sensitivity than water but that the enhancement can be appropriately adjusted by changing either the cation or the anion of the ILs. For example, the sensitivity in [[BMIm].sup.+][[Tf.sub.2]N].sup.-] is ~26 times higher than in water. It can be increased up to 31 times by changing the anion to [[P[F.sub.6].sup.-] (i.e., [[BMIm].sup.+][[P[F.sub.6]].sup.-]) or to 35 times by changing the cation to [[OMIm].sup.+] (i.e., [[OMIm].sup.+][[Tf.sub.2]N].sup.-]). In fact, the sensitivity of thermal lens measurements in ILs is comparable to those in volatile organic solvents such as benzene, carbon tetrachloride, and hexane. However, the ILs are more desirable as they have virtually no vapor pressure. Furthermore, additional sensitivity enhancement (up to 42 times higher than that in water) can be achieved by simply adding surfactants into the ILs. Based on the thermal conductivity (k) and dn/dT values, calculated from the measured thermal time constant [t.sub.c] and thermal lens strength [theta], it is evident that the observed sensitivity enhancement by the ILs is due to their relatively better thermooptical properties. More specifically, the enhancement is due not to the relatively modest lowering of the thermal conductivity but rather to the substantial increase in their dn/dT values. Because of the relationship between dn/dT and d[rho]/dT, it is expected that ILs can serve as an attractive and superior solvent not only for thermal lens measurements but also for other photothermal and photoacoustic techniques as well. Also equally important is the fact that the thermal lens technique in particular and photothermal techniques, in general, can offer a unique means to determine themooptical and thermal physical properties of the ILs (e.g., thermal conductivity, thermal diffusivity, and phase transition temperatures). This type of data is currently lacking but is of extreme importance for implementing ILs as a solvent in various industrial applications.

A modified approach to thermal imaging is proposed that fully accounts for diffusion phenomena in a tomographic imaging algorithm. Target values and reconstruction results for thermal conductivity are found to be in good agreement with one another.

Thermal contact resistance between molten metal droplets like aluminum alloy 380 and bismuth and solid plates like steel and brass were measured. The result showed that thermal contact resistance values ranged from 10(super -7) to 3 x 10(super -6) m(super 2) K/W, increased with surface roughness and decreased with rising impact velocity.

Monte Carlo simulation is applied to investigate phonon transport in single crystalline Si nanowires. Simulation results suggest that the dispersion relation for nanowires obtained from elasticity theory should be used to evaluate nanowire thermal conductivity as the nanowire diameter is reduced to the sub-100 nm scale.

The three-dimensional hyperbolic heat conduction equation is solved to obtain the analytical solution of the temperature rise at the contact area between an asperity and a moving smooth flat. The present analyses can provide an efficient method to avoid the problem of being difficult to give the correct boundary conditions for the frictional heat conduction at an asperity. The mean contact area of an asperity which is needed in the heat transfer analysis is here obtained by a new fractal model. This fractal model is established from the findings of the size distribution functions developed for surface asperities operating at the elastic, elastoplastic and fully plastic regimes. The expression of the temperature rise parameter T/f (T: Temperature rise, f: friction coefficient) is thus derived without specifying the deformation style of a contact load. It can be applied to predict the T/f variations due to the continuous generations of the frictional heat flow rate in a period of time. The combination of a small fractal dimension and a large topothesy of a surface is apt to raise the contact load, and thus resulting in a large T/f value. A significant difference in the behavior exhibited in the parameters of temperature rise and temperature rise gradient is present between the Fourier and hyperbolic heat conductions; Fluctuations in the thermal parameters are exhibited only when the specimen material has a large value of the relaxation time parameter. [DOI: 10.1115/1.2000983]

Abstract: For incompressible isotropic elastic heat conducting solids we examine the classes of universal deformations that are controllable under homothermal conditions and, in respect of a general law of heat [...]

Transient solid-liquid phase change occurring in a phase-change material embedded in a metal foam is investigated and the merits of incorporating metal foam for improving the effective thermal conductivity of thermal storage systems are discussed. The metal foam acts to substantially decrease the response time of the system and overheating due to transient, is reduced even though the melt volumes are small.

The problem of hot spot in a submicron silicon-on-insulator transistor is addressed by using a model on the Boltzmann transport equation (BTE) incorporating full phonon dispersion effects. A structured finite volume approach is used to solve the BTE and the results from the full phonon dispersion model are compared to those obtained using a Fourier diffusion model.

The continuum principles combined with van der Waals theory is employed to estimate the thermal contact resistance between nanowires and planar substrates. A trend observed in all calculations is that the interfaces resistance increases with smaller nanowires, showing that interfaces resistance would be a significant parameter in the design and performance of nanoelectronic devices.

A novel method combining effective medium theory and the finite differences method is introduced to model the effective thermal conductivity of cylindrical-particle-laden composite materials. Results from this model for different volume fractions, on average, are found to lie within plus or minus 5% percent of experimental thermal conductivity data.

A hybrid solution algorithm for the two-phase flow equations coupled to wall heat conduction is presented. The hybrid solution algorithm couples two solution methods, the solution method currently employed by RELAP5 and an implicitly balanced solution method and the resulting hybrid solution method is both fast and accurate.

The continuum Navier-Stokes and heat conduction equations for stochastic rotation dynamics, a particle based algorithm for simulating a fluid is derived using a kinetic theory approach. The expressions for the viscosity and thermal conductivity in two or three dimensions are obtained and analyzed.

A study is carried out on a photo thermal experiment, which is designed and conducted to characterize the thermal transport in carbon nanotube (CNTs) along the axial direction exclusively. The unique structure of the CNTs characterized indicates that the thermal transport in the axial direction is across the carbon atomic layers.

A study is carried out on the Fe nanofluids that are prepared with ethylene glycol and Fe nanocrystalline powder synthesized by a chemical vapor condensation process. The results shows that the thermal conductivity of a Fe nanofluid is increased nonlinearly up to 18% as the volume fraction of particles increases up to 0.55 vol.%.

The photopyroelectric technique is made use of in measuringthe effective thermal diffussivity of metal powders at room temperatures. The theory gives a precise estimation of thermal conductivity for metallic powders with a narrow size distribution of spherical particles and it underestimates the value in the case of a wide size distribution or in the case of irregular particles.

An experiment was designed and constructed to measure the conduct resistance between spheres in elastic deformation. A correlation was obtained relating the contact resistance with the contact radius, and results also showed the contact resistance to have minimal transient behavior.

A finite element method (FEM)formulation for the prediction of unknown steady boundary conditions in heat conduction for multidomain three-dimensional (3D) solid objects is presented. The FEM formulation is capable of determining temperatures and heat fluxes on the boundaries where such quantities are unknown, provided such quantities are sufficiently overspecified on other boundaries. An inverse finite element program has been previously developed and successfully tested on 3D simple geometries. The finite element code uses an efficient sparse matrix storage scheme that allows treatment of realistic 3D problems on personal computer. The finite element formulation also allows for very straightforward treatment of geometries composed of many different materials. The inverse FEM formulation was applied to the prediction of die-junction temperature distribution in a simple ball grid array electronic package. Examples are presented with simulated measurements, which include random measurement errors. Regularization was applied to control numerical error when large measurement errors were added to the overspecified boundary conditions.

The study deals with the calculation of the thermal transport cross section and phase function of longitudinal phonons for scattering by nanoparticles and microparticles. The formulations developed will be useful for the predictive modeling of thermal conductivity of practical systems such as nanocomposites and nanomicro particle laden system.

In a suspension of reverse micelles, in which the surfactant sodium dioctyl sulfosuccinate (AOT) separates a water nanodroplet from a bulk nonpolar C[Cl.sub.4] phase, ultrafast vibrational spectroscopy was used to study vibrational energy transfer from the nanodroplet through the AOT interracial monolayer to the surrounding C[Cl.sub.4]. Most of the vibrational energy from the nanodroplet was transferred to the polar AOT head group within 1.8 picoseconds and then out to the C[Cl.sub.4] within 10 picoseconds. Vibrational energy pumped directly into the AOT tail resulted in a slower 20- to 40-picosecond transfer of energy to the C[Cl.sub.4]., The flow of heat between two bulk phases separated by an interfacial monolayer is usually a simple function of the thermal conductivities of the two phases. However, when the heat [...]

A study is conducted to examine the determination of heater triggering parameters of high-T(sub c) superconducting (HTS) power supply with series-connected double-pancake load. Based upon the analysis, the 8 A electromagnet current and the 1.5 A dc heater current are derived and 8 s and 20 s for the pumping period are selected.

A study is conducted to examine the influence of inter-strand electrical and thermal conductivity on the stability of Rutherford superconducting cables in dipole magnets for particle accelerators. The results show that differences in inter-strand contact properties could lead to different ramp-rate limitation behavior.

Free space Green's functions are derived for graded materials in which the thermal conductivity varies exponentially in one coordinate. Closed-form expressions are obtained for the steady-state diffusion equation, in two and three dimensions. The corresponding boundary integral equation formulations for these problems are derived, and the three-dimensional case is solved numerically using a Galerkin approximation. The results of test calculations are in excellent agreement with exact solutions and finite element simulations. [DOI: 10.1115/1.1485753]

Investigating the evaluated effect of alloying additions to Ag on thermal conductivity and mechanical properties of Ag-alloy sheathed Bi-2223 superconducting tape is discussed. It is observed that the addition of alloys significantly reduced the thermal conductivity.

This article addresses the use of boundary element method in conjunction with minimal energy technique for solving a geometrical inverse heat conduction problem. The problem considered in this study is to estimate the unknown inner boundary position in an irregular-shaped hollow body of which the inner boundary surface is subjected to a specified temperature condition. For solving the problem, first boundary element equations are converted into the quadratic programming problem by minimizing the energy functional with a constraint, next a hypothetical inner boundary is defined such that the actual inner boundary is located interior of the hypothetical solution domain, then temperatures at hypothetical inner boundary are determined to meet the constraints of measurement error in inner surface temperatures, and finally boundary element analysis is performed for the position of an unknown boundary. Based on these main solution procedures, an effective detection algorithm is provided. In addition, the solution method is numerically tested to investigate the effects of measurement errors on the accuracy of estimation.

This article compares the condensation heat transfer in a bundle of copper Gewa C+ tubes with those of trapezoidal shaped fin tubes using pure refrigerant or binary mixtures of refrigerants. Data indicate that for the bundle and pure fluid combination, the inundation of the lowest tubes strongly influence the Gewa C+ tube performance.