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The ampacity of buried cables is significantly influenced by the thermal properties of the burial environment. When these thermal properties are not homogeneous it is usually necessary to utilize simulations with a relatively high computational cost that may also use commercial software. In this paper an alternative approach is proposed using conformal maps. Temperature is calculated in an annular domain which is a conformal mapping of the half plane space. Circumferential dependence is captured by expanding temperature as a Fourier series, a finite difference solver then determines temperature components radially. The model is as flexible as any two-dimensional slice model of heat transfer through thermal conduction only. Two case studies are considered: three land-based cables in planar configuration and a submarine export cable. The thermal properties of both burial environments are based on conditions which may be encountered in the field and exhibit a high level of stratification. Using a finite element analysis simulation as a benchmark, typical percentage differences in cable ampacities were 0.5%−1%. In addition to accuracy and flexibility the low computational cost of the proposed approach allows for large parameter sweeps, which may be required in a design phase, without requiring commercial software. [ABSTRACT FROM AUTHOR]

Rare-earth barium copper oxide (REBCO) tape is used for resistive type superconducting fault current limiters (RSFCLs) owing to its quick response and simple structure. To shorten the recovery time, film boiling on the REBCO tape should be suppressed as it exhibits poor heat transfer performance. To address the aforementioned issue, this study utilized low thermal conductivity materials as the thermal/electrical interface material for porous-stabilized REBCO tape. The experimental results showed that the cooling and recovery performances were dramatically improved by utilizing an insulating epoxy, which has a thermal conductivity of 0.6 W/mK. Based on the visualization of the boiling behavior, the liquid-solid contact between liquid nitrogen and the REBCO tape was promoted by the insulating epoxy, in which the film boiling was easily broken. [ABSTRACT FROM AUTHOR]

Considering that SF6 is a potent greenhouse gas, SF6/N2 gas mixtures are preferred to serve as the insulating gas for its environmental friendliness and good insulation. Since heat transfer analysis is very useful for ascertaining the appropriate temperature rise range, which can ensure the safe operation and extension of remaining useful life of GIL, it is essential to study the thermal properties of SF6/N2 gas mixtures. Nevertheless, very few studies investigate on the temperature field of SF6/N2 gas mixtures under ideal conditions. To reflect the heat transfer characteristics accurately, in this paper, by using the finite-element method and multi-physics coupling, the heat transfer properties in the GIL is analyzed by using a three-dimensional (3-D) axisymmetric GIL model. By varying the SF6/N2 mixing ratio and observing the corresponding heat transfer characteristics, the mapping between SF6/N2 mixing ratio and the temperature rise is obtained by using the model. Furthermore, the mappings are studied under different gas pressures, line currents and ambient temperatures, which correspond to different real-life operating conditions. The proposed strategies can effectively give guidance of choosing proper SF6/N2 mixing ratio for desired temperature rise, and thus having great values of practical applications. [ABSTRACT FROM AUTHOR]

In this article, pressure drop and thermal characteristic of the staggered strip fin (SSF) microchannel were investigated by using the simulation method. In recent decades, the pressure drop and thermal properties of many fins with different geometries were studied. However, the SSF has a high heat transfer coefficient (HTC) and the highest heat conductance at uniform pumping power. We believe that SSF can be widely used in IC cooling, so it was studied systematically in this article. First, the feasibility of simulation method was verified with the experimental results in a reference. Then, the design of experiment (DOE) was performed to investigate the effect of fin configuration on the pressure drop between the inlet and the outlet of microchannel and the thermal resistance between the base and inlet of microchannel. The results show that the pressure drop is decreased by about 200%, and the thermal resistance is increased by about 100% with channel pitch increased by two times. The ratio of fin width to channel width increased from 0.5 to 1.5, resulting in an increase in pressure drop of about 200% and no significant change in thermal resistance. There is no obvious change in pressure drop and thermal resistance when the fin length and end angle are increased. Finally, the formulas for predicting pressure drop and convective HTC (CHTC) were fit by 220 sets of simulation results, and the formula for predicting thermal resistance was deduced by theory. In addition, the validity of prediction formulas was verified, and the application range of the formula was studied preliminarily. [ABSTRACT FROM AUTHOR]

The paper presents the results of investigations on the thermal properties of cellulose and aramid paper impregnated with various liquid insulations. The liquid insulations investigated were mineral oil, synthetic ester, and natural ester. The heat transfer coefficient of the liquid was calculated on the basis of measurements of the thermal expansion, specific heat, density, thermal conductivity and kinematic viscosity of the liquid insulations. Temperatures in the paper and liquid insulations were calculated. The results allow to select the best paper and liquid insulations which provide the most effective cooling in transformers. [ABSTRACT FROM AUTHOR]

Electrosurgical vessel joining is commonly performed in surgical procedures to maintain hemostasis. This process requires elevated temperature to denature the tissue and while compression is applied, the tissue can be joined together. The elevated temperature can cause thermal damages to the surrounding tissues. In order to minimize these damages, it is critical to understand how the tissue properties change and how that affects the thermal spread. The purpose of this study is to investigate the changes of tissue thermal conductivity and how the changes correlate to thermal dose during the joining process. We propose a hybrid method combining experimental measurement with inverse heat transfer analysis to determine thermal conductivity of thin tissue sample. Porcine aorta arterial tissues were used to investigate tissue thermal conductivity with variable thermal dose. Different joining times were used to create different amounts of thermal dose. A 36% decrease in tissue thermal conductivity was found when the thermal dose reaches the threshold for second-degree burn. When thermal dose is beyond the threshold of third-degree burn, the tissue thermal conductivity does not decrease significantly. A regression model was also developed and can be used to predict tissue thermal conductivity based on the thermal dose. [ABSTRACT FROM AUTHOR]

Infrared (IR) emissivity is a critical parameter for modeling and predicting heat transfer by radiation. Microwave absorbing materials, having a high emissivity in the microwave spectrum, are crucial in a wide array of applications, such as electromagnetic interference mitigation, stealth technology, and microwave remote sensing and radiometer calibration. Accurate knowledge of the thermal properties of these materials is necessary for efficient design and optimization of these types of systems. Typical microwave absorbing materials consist of a dielectric epoxy material impregnated with a lossy material, such as iron or carbon. We study a novel cryogenically compatible epoxy-based absorber material that has been loaded with varying concentrations of carbonyl iron powder (CIP). We study six materials with CIP concentrations of 0%, 5%, 10%, 20%, 30%, and 50% by tap volume. We use a commercial IR camera with sensitivity in the range 7.5– 13~\mu \textm to measure the radiance of the samples and a waterbath IR blackbody at ten temperatures between about 19 °C and 45 °C. A linear Deming fitting is performed, considering uncertainties in both the measured parameters, and the slope of the linear fit is shown to be the IR emissivity, averaged over the spectral response of the camera. The emissivity ranges between 0.868 and 0.757, decreasing monotonically as a function of iron carbonyl concentration between 0% and 50%. The uncertainty of the emissivity determination method is derived and presented. The uncertainty of the presented method is shown to be no larger than 3.3% for all measured samples. [ABSTRACT FROM PUBLISHER]

This paper reports the first thermal model and detailed analysis of the heating of an electromagnetic (EM) skin-equivalent phantom with a finite thickness at 60 GHz. The 1-D heat transfer equation is solved analytically for homogeneous phantoms with finite thicknesses. The temperature rise dynamics and heating distribution within the phantom are calculated for several phantom thicknesses (5, 10, and 15 mm) using measured thermal properties of the phantom. Analytical results are confirmed by numerical analysis based on EM-thermal cosimulations. Furthermore, the numerical model is validated by measurements using an experimental setup based on the high-resolution infrared thermometry. The impact of uncertainty of EM and the thermal parameters of the numerical model upon heat deposition is also studied. Our results reveal that, for short exposure durations (i.e., less than 1 min), the surface temperature is well described by the semi-infinite and finite-thickness phantom models, whereas, for longer exposures (more than 1 min), finite-thickness models must be used to properly account for heating accumulation close to the phantom boundaries. While the reported results cannot be directly used for predicting temperature increase in skin, they are of importance for temperature-based dosimetric assessment in the millimeter-wave band using currently available homogeneous phantoms. [ABSTRACT FROM PUBLISHER]

Microfluid cooling solution is one of the most effective techniques for thermal management of high heat fluxes. A jet-based Si microcooler with multiple drainage microtrenches (MDMTs) has been developed for microelectronic thermal management. Integrated with MDMT in hybrid microcooler, the negative cross-flow effect between nearby nozzles is eliminated, and thus fully developed jet impingement can be enabled for each nozzle. An inlet/outlet flow arrangement layer has been introduced to achieve uniform pressure distribution. The effects of three types of arrangement structures on the hydraulic and thermal performance of microcooler have been analyzed and compared. Two different thermal/fluid simulation models have been constructed for microcooler design. The test vehicle with the new nozzle/trench layer is fabricated using double-side deep reactive-ion etching process. Assembly of the stacked microcooler and Si thermal test chip is finished through two-steps optimized thermal compression bonding process. With 0.05-W pumping power for the microcooler, the heat dissipation of 260 W/cm2 has been demonstrated, and the chip temperature can be maintained under 51 °C. Excellent agreement has been obtained between experimental and simulation results. With the MDMT, enhanced-microjet array impinging has been achieved, and uniform chip temperature distribution is obtained. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a new method for estimating the peak junction temperature and thermal resistance in modern heterojunction bipolar transistors (HBTs). The proposed method uses the temperature dependence of thermal conductivity of the material. The method is analytic in nature and does not require any iteration as opposed to the existing state-of-the-art model. This analytic method can easily include the available scaling relations relevant to specific technology to estimate the junction temperatures and thermal resistances of the corresponding transistors. The analytic model is tested against iterative self-consistent solutions for simple structures without any trench isolation and for structures corresponding to the ST Microelectronics B9MW technology that includes shallow and deep trench isolations. The model is slightly modified in order to include the effects from the back-end-of-line metal layers. The resulting analytic model is validated against the measured results for silicon germanium HBTs fabricated in ST Microelectronics B9MW technology. [ABSTRACT FROM PUBLISHER]

The thermal model of energy storage elements such as batteries or supercapacitors (SCs) can be used as a platform to predict thermal behavior of the elements, which is essential from the point of view of monitoring and diagnostics. While the lumped thermal model for a single cylindrical SC cell and its extension to multicells string or module have been covered in technical literature, the multicells model has not been experimentally validated. This paper presents experimental validation of the existing lumped thermal model of multicylindrical cells based on an experimental setup of a forced cooled SC string consisting of eight 650 F cells. The determination of the parameters of such a thermal model is discussed and the validated model is used as a basis to design a closed-loop observer for estimating string temperature. Experimental results are presented to confirm its applicability for predicting instantaneous temperatures of each cell in the string. [ABSTRACT FROM AUTHOR]

Excellent electrostatic control offered by gate-all-around (GAA) geometry makes multinanowire (multi-NW) MOSFET a promising candidate for sub-10-nm technology nodes. Unfortunately, the GAA geometry is susceptible to the increased self-heating due to poor heat dissipation from the nanowires (NWs) to the substrate. Therefore, an understanding of spatio-temporal temperature rise, \Delta T(x,y,z; t) , at the NW level is important for predicting activity-induced variability within an IC, as well as characterization of various reliability issues, such as, NBTI, PBTI, HCI, and TDDB that depend sensitively on self-heating. In this paper, a 3-D electrothermal simulation model is developed to explore and interpret self-heating and heat dissipation in GAA devices. Our results identify complex heat dissipation pathways characterized by multiple time constants. First, the nanowires heat up quickly ( \tau _{\textrm {GAA-NW}}\sim \textrm {nSec} ), then heat spreads all over the gate contact pad ( \tau _{\textrm {G-pad}}\sim 100$ nSec), and finally, the heat exits through the heat sink at the bottom of the substrate ( \tau _{\textrm {sub}}\sim \textrm {mSec} ). A systematic thermoreflectance measurement of temperature helps us to identify the time constants, and validates the model. Our results have implications for the design, characterization, circuit-operation, and reliability of high-performance GAA devices. [ABSTRACT FROM AUTHOR]

The performance and reliability of the high-power light-emitting diodes (HP LEDs) are closely related to the quality of the die attach adhesive (DAA) layer, because voids or delaminations in the layer may cause higher junction temperature, and even result in the break of the chip. In this paper, a dynamic compact thermal model is constructed for an independent HP LED without being attached on a cold plate. The time-constant spectrum method based on the thermal model is applied to characterize the transient thermal behavior of the DAA layer and other layers along the heat flow path. Thermal transient experiments are carried on HP LED samples with different DAA dosages. The theoretical and experimental results demonstrate that the time-constant spectrum for LEDs tested without cold plate can reflect the thermal characteristics of the DAA layer as well as that with cold plate. Differences in the HP LED samples with different DAA layers can be obviously distinguished in the time-constant spectrums as well. Compared with the traditional testing method with cold plate, direct test in air for HP LEDs has the advantages of easy operation, time saving, and no pollution to samples. [ABSTRACT FROM AUTHOR]

A 3-D test circuit examining thermal propagation within a through-silicon via-based 3-D integrated stack has been designed, fabricated, and tested. Design insight into thermal coupling in 3-D integrated circuits (ICs) through both experiment and simulation is provided, and suggestions to mitigate thermal effects in 3-D ICs are offered. Two wafers are vertically bonded to form a 3-D stack. Intraplane and interplane thermal coupling is investigated through single-point heat generation using resistive thermal heaters and temperature monitoring through four-point resistive measurements. Thermal paths are identified and analyzed based on the metric of thermal resistance per unit length. The peak steady-state temperature due to die location within a 3-D stack is described. The reduction in peak temperature through fan-based active cooling is also reported. Thermal propagation from a heat source located on the backside of the silicon is examined with both back metal and on-chip thermal sensors. A comparison of thermal coupling between two different heat sources on the same device plane is also provided. [ABSTRACT FROM PUBLISHER]

Heat exchangers are important facilities used in data center cooling systems. The effectiveness of heat exchangers strongly influences the thermal performance of cooling systems. Rear door heat exchangers, in-row, overhead coolers, and fully contained cabinets are some examples of executing liquid and hybrid cooling systems used in data centers. A liquid to liquid heat exchanger is an important component of the coolant distribution unit, which supplies chilled water to the aforementioned heat exchangers. Computer room air handler units are also typically liquid to air cross flow heat exchangers. It is important to characterize the dynamic behavior of these heat exchangers for the thermal management of data centers, to improve the design of control strategies, and energy efficiency. The transient response of a 2-D unmixed–unmixed cross flow heat exchanger, with a finite wall capacitance, is investigated. The transient effectiveness concept is used to build the mathematical models that will be used to solve and analyze the transient problems involving cross flow heat exchangers. Several transient cases are investigated numerically for step, ramp, and exponential variations in the inlet temperature of the minimum capacity rate fluid, as well as step and ramp changes in the flow rate of hot and cold fluids. The transient effectiveness characteristics are tested in parametric studies. The results obtained show that transient effectiveness is a useful method of analyzing and predicting the dynamic performance of cross flow heat exchangers. [ABSTRACT FROM PUBLISHER]

\MgB2 and high-temperature superconducting (HTS) magnets might be better cooled using a cooler if they operate in the temperature range from 15 to 40 K. Liquid neon has been considered as a fluid for cooling such magnets. Neon can only be used in the upper part of the temperature range; neon is scarce and has poor thermal properties when compared to hydrogen or helium. For many \MgB2 and HTS magnet applications, liquid hydrogen is an ideal working fluid. Liquid hydrogen has a high heat of vaporization, a high specific heat, and excellent heat transfer properties. This paper describes the kind of thermal siphon cooling loop that can be used for cooling-down a superconducting magnet and keeping it cold in the range from 15 to 28 K. This report will present a method for using hydrogen gas to cool-down and cool a magnet that is relatively safe. [ABSTRACT FROM PUBLISHER]

The heat generation of electronic systems has been increasing because of the increase in the speed and density of such systems. High-power light-emitting diode and power semiconductor modules are examples of electronic systems that exhibit the aforementioned thermal problem. Recently, microsized cooling devices that are developed using the semiconductor process of silicon and glass have been used as electronic cooling solutions. However, microsized cooling devices with an equivalent diameter of less than 1 mm have low cooling capability close to 10 W. Therefore, cooling devices that have high cooling capability are needed in the field of electronic cooling. In this paper, a woven wire wick with a high capillary limit and high productivity was developed, and small-sized heat pipes with outer diameters of 3 and 4 mm were designed, manufactured, and tested. Performance test results show the maximum cooling capability of 27.9 W at a working temperature of 90 ^\circC for the small-sized heat pipe with length of 300 mm and outer diameter of 4 mm. The capillary radius distributions in the vapor-liquid meniscus and the pressure distributions in the vapor and liquid paths were obtained through numerical analysis. The obtained maximum cooling capability at various working temperatures was compared with the experimental results. The maximum cooling capability was compared with that of other wick structures as well. [ABSTRACT FROM PUBLISHER]

The small signal gain and phase and polarization distortions of laser radiation have been investigated theoretically and experimentally in end-pumped Yb:YAG thin-disk and Yb:YAG/YAG composite active element under nonlasing conditions. Comparison of experimental data with calculation results reveals an additional heat release whose negative influence is three times stronger than that of amplified spontaneous emission in the thin-disk active element. [ABSTRACT FROM PUBLISHER]

The weldability of resistance spot welding affected by different thermal, physical, and metallurgical properties is extensively investigated by realistically computing transient mass, momentum, energy, species, and magnetic field intensity transport in the alloy workpieces and electrodes. The properties considered are the thickness, radius, equilibrium partition coefficient of workpieces, electrode-to-workpiece electrical conductivity ratio, thermal conductivity ratio, and a joule heat-to-enthalpy change parameter. Resistance spot welding has been widely used in joining thin workpieces in various electronic packaging and manufacturing industries. Understanding of physical mechanisms for easily manipulating and controlling weld qualities in advance is important. This paper accounts for electromagnetic force, heat generations due to contact resistances at the electrode–workpiece interface and faying surface between workpieces, and temperature-dependent bulk resistance of the workpiece. The contact resistances are functions of hardness, temperature, electrode force, and surface condition. The computed results in general dimensionless expressions show that the welding is feasible or onset time is shortened by decreasing thickness, radius, equilibrium partition coefficient of the workpiece, and electrode-to-workpiece electrical conductivity and thermal conductivity ratios, and increasing the joule heat-to-enthalpy change parameter. The corresponding heat transfer and species patterns are also presented. [ABSTRACT FROM AUTHOR]

In hadron colliders such as the LHC, the energy deposited in the superconductors by the particles lost from the beams or coming from the collision debris may provoke quenches detrimental to the accelerator operation. In previous papers, a Network Model has been used to study the thermodynamic behavior of magnet coils and to calculate the quench levels in the LHC magnets for expected beam loss profiles. This model was subsequently used for thermal analysis and design optimization of \ Nb3{\ {Sn}} quadrupole magnets, which LARP (US LHC Accelerator Research Program) is developing for possible use in the LHC luminosity upgrade. For these new magnets, the heat transport efficiency from the coil to the helium bath needs to be determined and optimized. In this paper the study of helium cooling channels and the heat evacuation scheme are presented and discussed. [ABSTRACT FROM PUBLISHER]

The thermal properties of a high-power vertical-external-cavity surface-emitting laser (VECSEL) are studied experimentally, focusing on the generation, distribution, and removal of excess heat under extreme pumping conditions. Different heat-spreading and heat-transfer approaches are analyzed. The performance of the device is optimized yielding a maximum emitted power beyond 70 W from a single spot. Finally, the potential for power-scaling in VECSELs and its restrictions are examined. [ABSTRACT FROM PUBLISHER]

A novel, integrated approach in thermal management of electronic products, based on two-phase cooling, is presented. A flat miniature heat pipe, integrated inside the laminated structure of a printed circuit board (PCB) has been developed, based on mainstream PCB fabrication processes. Hot spots on the PCB, caused by heat dissipating components, can be cooled with relatively small temperature gradients across the board. An analytical model is presented to predict the behavior of the embedded heat pipe for various geometries, orientations, and operating temperatures. Experimental verification has shown successful heat pipe operation. The heat pipe exhibited a measured equivalent thermal conductivity more than seven times higher than solid copper. Low-thermal resistance values establish this concept as a promising thermal management solution for future electronic products. As mainstream manufacturing techniques are applied, thin PCBs with integrated cooling support can be produced at low-cost. [ABSTRACT FROM AUTHOR]

The thermal and magnetic properties of (Fe75B20Si5)93Nb4Y3 and (Fe78B14Si8)93Nb4Y3 metallic glasses, in cylinder and ribbon form, have been studied and compared. Bulk samples were prepared by water-cooled Cu-mold casting technique. Ribbons having the same compositions have been prepared by rapid quenching. Selected samples have been submitted to furnace annealing to study the crystallization behavior and the corresponding structure has been studied by X-ray diffraction technique. Room-temperature hysteresis loops and magnetisation behavior as a function of temperature have been measured by a Vibrating Sample Magnetometer (VSM). In this paper, the effect of small addition in the rapidly solidified ternary system Fe78B14 Si8 either on the glass formation or the magnetic properties will be shown. [ABSTRACT FROM AUTHOR]

Using the governing equations for internal fluid flow and heat transfer, scaling laws are developed to predict how the selection of a liquid or gas coolant and geometry affects the pumping power and volume requirements of heat sinks in electronics cooling applications. One of the principal outcomes of the presented scaling analysis is derivation, based on first principles, of new figure-of-merit parameters that can be used to evaluate cooling performance and guide efforts on development of new cooling fluids. The new figures-of-merits are critically compared to existing performance metrics and experimental data from the literature to emphasize the relevance and accuracy of developed scaling laws. [ABSTRACT FROM AUTHOR]

In this paper, we present a new technique to calculate the power dissipation profile from the IC temperature map using a process analogous to image processing and restoration. In this technique, finite-element analysis (FEA) is used to find the heat-point spread function (heat PSF) of the IC chip. Then, the temperature map is used as input for an efficient image restoration algorithm which locates the sources of strong power dissipation non-uniformities. Therefore, it optimally solves the inverse heat transfer problem, and estimates the IC power map without extensive lab experiments. Our computationally efficient and robust method, unlike some previous techniques, applies to many experimental scenarios. Simulation results on a typical commercial integrated circuit chip confirm the effectiveness of our proposed method. [ABSTRACT FROM AUTHOR]

Pool boiling from a surface featuring micropyramidal reentrant cavities (mouth size 40 μm) etched in silicon, bonded to a glass substrate, was studied. All experiments were conducted in the dielectric fluid FC-72 at 1 atm. The heat sink is designed to eliminate spreading through the substrate, and back heat loss. Experimentation showed that the critical heat flux was 12.8 W/cm². A high speed camera (400 frames/s) was used to record and quantify the effect of heat flux on departure diameter and bubble emission frequency. Both departure diameter and frequency showed an increasing trend with heat flux. Comparisons with existing literature are also presented. [ABSTRACT FROM AUTHOR]

This study numerically examines the influence of inlet locations on the performance of the Multichannel cold-plates. A total of five inlet configurations (namely I-, Z-, ]-, L-, and Γ-arrangement) are investigated in this study. The velocity maldistribution and nonuniformity of temperature field caused by the fluid flow are shown in the simulation. For I-arrangement, higher inlet flow rate of the cold-plate shows more considerable maldistribution, and this maldistribution is decreased when the number of channels of the cold-plate is increased. The Z-arrangement and L-arrangements show a pronounced flow-recirculation that eventually leads to a much larger temperature difference along the surface of the cold-plate. Conversely, there is no flow recirculation in the ]-arrangement and a comparatively uniform flow distribution is seen. For the same average inlet velocity, I-arrangement has the highest pressure drop whereas ]-arrangement shows the lowest pressure drop. The I- and Γ-arrangement give the best heat transfer performance due to their impingement configurations whereas the Z-arrangement shows the lowest heat transfer performance for its dramatic flow recirculation and maldistribution. [ABSTRACT FROM AUTHOR]

In order to enhance the trapped field in cryo-cooled HTSC bulks using pulse field magnetizing (PFM), a metal ring (stainless steel 304 and/or Al) has been tightly set onto the Sm-BaCuO bulk disk and the relation between the total trapped flux ΦTP the trapped field BTP, and the temperature rise ΔT, has been investigated as a function of the applied pulse field Bex. The ΦTP and BTP values are enhanced about 10∼ 20% by the metal ring due to the reduction in the temperature rise ΔT. These results Suggest that a part of the generated heat Q due to the flux motion in the peripheral region promptly transfers to the metal ring and the heat transfer to the cold stage is improved by the ring setting. [ABSTRACT FROM AUTHOR]

Presents information on a study which described thermal performance of an aluminum silicon carbide (AlSiC) metal matrix composite base plate with integral cooling fins. Techniques that were employed to model the thermal and hydrodynamic resistance characteristics through the pin fin structure of a prototype base plate design; Numerical and experimental results; Conclusions.

Part I. Discusses the issues related to derating of cables caused by the presence of a separate heat source. Survey of utilities' practices regarding cable crossings; Analytical solution for the computation of the derating factors; Ampacity reduction modeling; Approaches to reduce the mutual heating effect.

A transient two-dimensional optical-thermal model that accounts for dynamic changes in optical and thermal properties with temperature was developed to investigate the mechanisms leading to thermal damage during laser tissue soldering. The model was implemented using the electrical circuit simulator simulation program with integrated circuit emphasis (SPICE). Electrical analogies for the optical and thermal behavior of the solder and tissue mere established. With these analogies, light was propagated using a flux representation of the light and the electrical simulator mas used to calculate heat transfer with an algorithm based on the finite difference technique. Thermal damage was calculated using the Arrhenius rate process relation. Temperature-dependent absorption and scattering coefficients, thermal conductivity and thermal diffusivity, mere incorporated in the SPice optical-thermal simulation (SPOTS), as well as the time domain behavior of a scanning laser source. Experimental results from an in vitro study performed using an 808-nm diode laser in conjunction with indocyanine green-doped albumin protein solders to repair bovine aorta specimens compared favorably with numerical results obtained from SPOTS using dynamic optical and thermal properties. The maximum surface temperature was over-estimated by almost 10% when dynamic properties were not taken into account. This difference corresponds to over two orders of magnitude difference in terms of the Arrhenius tissue damage integral. The incorporation of dynamic changes in optical and thermal properties of tissue during laser-induced heating represents a significant advance in computer modeling of laser tissue interactions [ABSTRACT FROM PUBLISHER]

Two assembling methods, i.e., the sputter brazing method and the diffusion brazing method, have been developed for improving the heat dissipation capability of the helix traveling-wave tube slow-wave structure (SWS). The magnetron sputter plating technology and the pressure diffusion technology are employed in this letter to complete the SWS assembly. The effect of these two methods on the thermal conduction of the SWS was verified by several experimental tests. These two methods being pursued enable better heat dissipation capability of the helix SWS, compared to the conventional nonbrazing methods. [ABSTRACT FROM AUTHOR]

In this paper, electrospinning is shown to be an effective method for overcoming the agglomeration of nanosilica in silicone rubber nanocomposites. Silicone rubber nanocomposites with 7 nm silica were produced using conventional mixing and electrospinning processes. Scanning electron microscopy is used to demonstrate homogenous filler dispersion in electrospun samples as compared to conventional mixed samples. Thermo-gravimetric analysis and infrared-laser-based thermal tests show significant improvements in thermal stability and heat transfer in electrospun nanocomposites. However, no significant improvements in either the mechanical properties or relative permittivity between the electrospun and conventional mixed samples were found. The improved thermal properties of the electrospun silicone rubber nanocomposites are attributed to the significantly reduced nanofiller agglomeration and their uniform dispersion. [ABSTRACT FROM PUBLISHER]