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In a high-power semiconductor power module where multiple chips are populated in parallel, the thermal imbalance problem arises. In this article, the next-generation standard high-voltage insulated-gate bipolar transistor module for high-speed railcar traction is investigated to characterize the internal thermal imbalance among paralleling chips and evaluate the impact on temperature distribution in field application. The former is accomplished by a new test algorithm with a purposely designed module sample, while the latter is achieved via an advanced electro-thermal simulation from chip level to system level. The experimentally verified thermal network among paralleling chips reveals the multiple reasons for the thermal imbalance. A comparison between the simulation and experimental results regarding the paralleling chips’ power-cycling scenario helps to confirm the effectiveness of the chip model, the thermal network, and the electro-thermal simulation approach. A further electro-thermal simulation shows that the module internal thermal imbalance can lead to significant junction temperature discrepancy among paralleling chips in traction inverter applications, which should be taken into consideration for the long-term reliability assessment. [ABSTRACT FROM AUTHOR]

In this article, silicone rubber (SiR) is filled with industry preferred micro-silica and specialty hexagonal boron nitride (h-BN) nanosheets, by varying the ratio between the two fillers, while keeping the filler to matrix ratio the same in all three composites. The fillers are added to SiR using an electrostatic disperser which aids in homogenizing the filler-polymer mixture by means of shearing force along with elongation. The performance of synthesized silicone composites are evaluated using thermal, erosion resistance, morphological, mechanical, and high-temperature dielectric properties. Addition of as low as 5 wt% h-BN fillers significantly improved the thermal properties; 6%–20% improvement in thermal conductivity and in less than half the weight loss compared to only silica filled composites with laser erosion. The morphological and mechanical analyses showed improved filler dispersion and filler to silicone matrix interaction owing to good filler dispersion achieved through the electrostatic dispersing method. The dielectric properties measured in wide frequency range, between 10−4 and 103 Hz and at elevated temperatures (up to 175 °C) showed a negligible effect of increase in h-BN content. Thus, this article implies that low amounts of h-BN in silica-silicone composites improve thermal conductivity and erosion resistance significantly and not altering the dielectric responses of these hybrid composites even at elevated temperatures. Hence these composites can find applications both in the high voltage industry and as electronic packaging materials. [ABSTRACT FROM AUTHOR]

This article aims to improve nanofiller dispersion in epoxy resins by using an electrostatic disperser (ED), as well as reduce costs by using a combination of microfillers and nanofillers. The ED method aids in homogenized mixing of nanofillers in epoxy resin, due to its jet elongation and shearing effect on a polymer mix. In this article, two concentrations (7.5 wt% and 5 wt%) of nanosilica are used with resin, and the rheological properties of hybrid composites are tested before and after the addition of 50 wt% microsilica. It is observed that the electrostatic dispersion method aids in the network formation of nanosilica, unlike the high shear (HS) method, wherein clusters of nanosilica are formed. Hence, the ED method aids in reducing the viscosity values with the addition of microsilica, which is helpful in the product molding process. A plausible mechanism of filler dispersion is explained for ED and HS methods. The morphological analysis showed that the composites are brittle due to the high silica content, and that the silica fillers are dispersed well within the epoxy matrix. The flexural strength lies in the same range for both composites prepared using ED and HS methods. Thermal conductivity depends both on nanosilica and epoxy matrix dispersion, while heat deflection temperature, thermal diffusivity and specific heat depend on the dispersion method. [ABSTRACT FROM AUTHOR]

Thermal interface materials (TIMs) used to fill the gaps between chip and heat sink are one of the most important materials for electronic packaging. Low thermal resistance is the key to achieving high heat dissipation efficiency. However, most studies only focused on how to enhance the thermal conductivity of the gel TIMs and ignored the thermal resistance, which is significantly influenced by the rheological properties. In this work, we aimed to investigate the effects of in situ modification of aluminum fillers on the rheological properties and thermal resistance of the gel TIMs. Six modifiers were compared for their ability to improve the compatibility between aluminum fillers and silicone oil. The rheological results showed that the gel TIM modified with 0.170 wt% dodecyl trimethoxysilane had the best rheological properties, including the lowest viscosity and yield stress, the weakest Payne effect, and the shortest relaxation time. The thermal resistance measurements further verified that the bond line thickness and thermal resistance of gel TIMs were determined by the rheological properties. This work provides a reference for the formulation design and process optimization of gel TIMs. [ABSTRACT FROM AUTHOR]

Liquid dielectrics filled with nanoparticles have drawn huge attentions due to enhanced dielectric and thermal properties. Despite of great achievements have been made, the charging mechanisms of nanoparticles suspended in liquid dielectrics are still open questions. It is previously argued that field charging with Maxwell–Wagner relaxation fails to explain the enhanced breakdown strength when nanoparticles have longer relaxation time constant than the timescale of streamer development in liquid dielectrics. However, it is proven in this article when the condition that the charging time constant $\tau _{\mathrm {pc}} \ll $ the charging time $t_{\mathrm {pc}}$ is fulfilled, nanoparticles can acquire significant number of charges even if $t_{\mathrm {pc}} \ll $ relaxation time constant $\tau _{\mathrm {MW}}$. It is also showed that the field charging models for nanoparticles suspended in gases and liquids share the same formulation and thus can be unified. In addition, diffusion charging is proposed to be one of the charging mechanisms for nanoparticles in liquid dielectrics, and Fuchs’s model is extended from aerosol science to liquid dielectrics. It is demonstrated the diffusion charging could be far more important than field charging in liquid dielectrics. This work may bridge the gaps of charging mechanisms and models between gaseous and liquid dielectrics. [ABSTRACT FROM AUTHOR]

This article explores the potential of epoxy resin/silicon carbide whisker (EP/SiCw) composites (1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%) as the field-dependent conductivity (FDC) packaging materials for the high-voltage power modules by investigating their thermal and electrical properties at different temperatures. The cross-sectional morphology of the prepared materials is characterized by field emission-scanning electron microscopy (FE-SEM). The thermal analysis consists of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The electrical properties, such as dc conductivity, dielectric spectroscopy, thermally stimulated discharge current (TSDC), space charge distribution, and dc breakdown strength, are measured. The molecular orbital energy levels of the EP and SiCw monomers are calculated by quantum chemical calculation (QCC) to analyze the effect of EP interfacial trap sites on the electrical properties. The effect of the EP/SiCw interfacial charges and electrical field distortion on the electrical properties of the EP/SiCw composites with different filler content is investigated by the finite-element method (FEM) simulation. It is found that the 2 wt% EP/SiCw composite has a better thermal performance. The 1 wt% has lower real permittivity, lower trap density, lower space charge accumulation, and higher breakdown strength. The EP/SiCw composites have a higher trap level than the pure EP. The nonlinearity percolation threshold of the EP/SiCw composites is 3 wt%. As the filler content increases, the nonlinear conductivity coefficient of the EP/SiCw composites becomes higher, whereas the breakdown strength decreases due to the electric field distortion near the electrodes caused by the apparent hetero charge accumulation at high filler content. [ABSTRACT FROM AUTHOR]

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]

In a typical nitrogen glow discharge plasma, a large number of energetic neutrals, N2, are generated inside the cathode sheath. In this work, we are presenting a technique for the extraction of this energetic N2 for the treatment of starch. The energetic neutrals N2 were generated by the application of −500 V on a transparent cathode. On reaching the cathode, N2+ ions are absorbed; however, it is transparent to energetic N2 neutrals molecules generated inside the sheath by charge exchange collisions, as the energetic N2 neutrals are unaffected by the electric field and pass through the transparent cathode. The sample for treatment was placed below the transparent cathode and thus exposed to the energetic N2 neutrals extracted from glow discharge plasma for a duration of 30 min. The impact of energetic N2 neutral extracted from glow discharge plasma results in modification of physical and thermal properties of corn starch (maize starch). The physicochemical and morphological properties of treated and untreated samples were studied. The surface roughness of the plasma-treated corn starch increased significantly in comparison to the untreated sample. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) spectra confirmed that there is a considerable reduction in the semicrystalline nature and the polymer structure morphology of the corn starch. Scanning electron microscope (SEM) micrographs of samples show a substantial change in surface morphology and in size of the grains between the plasma-treated and untreated corn starch samples. The room-temperature thermal properties of the plasma-treated corn starch samples are measured using differential scanning calorimetry (DSC). The results confirm that the starch treated with energetic N2 molecules has a lower gelatinization temperature and could be applied in food processing industries. [ABSTRACT FROM AUTHOR]

This work reports on the significant enhancement of the thermal properties of the FR3 natural ester dielectric oil after the addition of pentyl-graphene nanosheets, as confirmed by thermal diffusivity and specific heat studies at different concentrations and temperatures (30 °C–90 °C). Experimental results of the dielectric constant demonstrated a constant value in the kHz region while increased in the low-frequency region, decreased with increased temperature, and saturated at 0.008% w/w concentration. In addition, light absorption is used for a better understanding of the properties variation upon changing graphene’s concentration as a method to estimate the agglomeration level. The optimum concentration for its best performance in terms of thermal and dielectric properties is 0.008% w/w, whereby the thermal diffusivity and the dielectric constant increased by 43.04% and 6.18%, respectively. [ABSTRACT FROM AUTHOR]

As a promising environmentally friendly insulating medium, C5F10O needs to be mixed with buffer gases such as technical air to avoid liquefaction. Notably, such a high proportion of oxygen can promote the decomposition of C5F10O and may even eradicate its stability under over-thermal fault. At present, there is still a lack of experimental research investigating the influence of oxygen on the thermal stability of C5F10O, and the mechanism is still unclear. To this end, experiments are carried out on the thermal decomposition properties of C5F10O while mixed with different proportions of O2. And to reveal the mechanism, the dissociation of C5F10O and the reaction of O2 with CF3CO $\cdot $ radical are studied theoretically based on the density functional theory (DFT) and transition state theory (TST). The results signify that oxygen of 4% and above ravages the thermal stability of C5F10O medium, causing it to decompose in a large amount at high temperature, which generates stable products such as CO2, C3F6, C3F8, and C2F6. The mechanism is that O2 is extremely easy to combine with CF3CO $\cdot $ radical to form a complex, which further decomposes, leading to the continuous development of the decomposition of C5F10O. The study revealed the important mechanism of O2 during the decomposition process of C5F10O, providing experimental and theoretical support for the use of C5F10O mixed gas. [ABSTRACT FROM AUTHOR]

In this review article, we have investigated the credibility and suitability of the lanthanum gallium silicate (La3Ga5SiO14, LGS) crystals in the application of high-temperature sensing. All the basic properties of the langasite family piezoelectric crystals, such as elastic properties, are taken into consideration and discussed. The crosstalk effects between different vibration modes of LGS crystal are investigated to optimize the crystal cuts. Thereafter, dependences of properties, such as electroelastic properties, resistivity, and electromechanical coupling coefficients of langasite family crystals on higher temperatures, are discussed. Finally, thermal-related properties of langasite family crystals, such as specific heat as well as thermal expansion coefficients, are studied for higher temperature ranges and a comparison with other piezoelectric crystals has also been presented. [ABSTRACT FROM AUTHOR]

We characterized the thermal behavior of a 65 nm bulk CMOS transistor, by measuring the self-heating effect (SHE) as a function of bias condition. We demonstrated that at a base temperature of 6.5 K the channel temperature of the transistor can increase up to several tens of kelvins due to power dissipation. The thermal behavior of the transistor is determined not only by the thermal response of the transistor itself but also by the thermal properties of the surroundings, i.e., source, drain, bulk, and gate interfaces, metal contacts, and vias. On top of it, the thermal response is bias-dependent through bias dependence of power and self-heating. This information becomes relevant for proper design of integrated circuits for quantum computing or other cryogenic applications, where the circuitry requires to be operated at a stable cryogenic temperature. [ABSTRACT FROM AUTHOR]

SiO2 encapsulated quantum dots (QDs@SiO2) have been widely adopted for fabricating high-performance phosphor-converted light-emitting diodes (QCLEDs). However, the impact of SiO2 thickness on the optical properties of QDs in QCLEDs remains largely unexplored. In this work, we studied the combined effects of light scattering, heat accumulation, and concentration quenching of QD@SiO2 on optical performance of QCLEDs. QDs@SiO2 nanoparticles with SiO2 thickness of 10–60 nm were developed to perform the experimental tests and optical and thermal simulations. Our study reveals that at low power density, QD@SiO2 with 20–30-nm SiO2 shell display optimal efficiency owning to suppressed self-absorption quenching and enhanced light scattering. However, because of heat accumulation inside QDs@SiO2 at high power density, thin SiO2 shell (10–15 nm) is more favorable to reduce thermal quenching and maintain luminous efficiency of QCLEDs. This study provides guidance for the development of appropriate QDs@SiO2 structure to meet application requirements of different QCLED devices. [ABSTRACT FROM AUTHOR]

Die-bonding materials are essential packaging materials for high-power light-emitting diodes (LEDs), which affects their heat dissipation and reliability. In this work, a die-bonding structure with high strength and low thermal resistance was proposed for high-power LEDs. A Cu-foam/Sn composite preform was prepared as the die-bonding material in this die-bonding structure. The composite preform is composed of high-melting-point Cu skeleton and low-melting-point Sn. The Cu-skeleton structure accelerates the bonding process and forms intermetallic compounds (IMCs) with high remelting point. Consequently, the die-bonding structure displays robust joints from the transient-liquid-phase (TLP) interconnection layer and high thermal conductivity from the Cu skeleton. The effects of bonding temperature on the mechanical and thermal properties of LEDs were investigated. After bonded with the Cu-foam/Sn composite preform, the LED achieves a low thermal resistance of 6.75 K/W, a low junction temperature change of 6.5 °C, and a high shear strength of 37.8 MPa. Moreover, the proposed die-bonding structure has a lower thermal resistance and higher light output power, which are 27.2% lower and 7.2% higher than the traditional die-bonding structure, respectively. [ABSTRACT FROM AUTHOR]

An accurate and efficient algorithm is presented, which allows deriving the structure function of a discretized 3-D heat conduction problem. In this approach, the partial thermal conductances and capacitances in the structure function are computed in terms of weighted spatial averages of thermal resistivity and volumetric heat capacity. As a result, the exact influence of all materials and geometric details on each part of the structure function is determined. The approach is validated on a state-of-the-art SiGe heterojunction bipolar transistor (HBT) for high-frequency applications. [ABSTRACT FROM AUTHOR]

Thermal and structural properties of aged silicone rubber composite insulators widely used in high-voltage transmission power systems were characterized by photothermal radiometry (PTR) to evaluate the degree of aging. A two-layer PTR theoretical model was developed to extract the thermal diffusivity and the aged layer thickness from the PTR frequency-scan data. Results show that aging generated an aged layer with a reduced thermal diffusivity at the surface of the composite insulator. Further investigation into the depth dependence of the thermal diffusivity of aged composite insulators found a monotonically increasing thermal diffusivity along the depth direction, approximating to a hyperbolic tangential profile, which indicates a spatially continuous variation from surface to bulk during the aging process. The PTR depth-profiling of thermal and structural properties provides a deeper understanding of the aging process in composite insulators. [ABSTRACT FROM AUTHOR]

Epoxy resin (EP) insulations are widely considered as potential candidates for various applications. However, it is not suitable for high frequency (HF) and high temperature (HT) applications due to its low thermal conductivity. This research presents the tuning of thermal and electrical properties of EP via resin stoichiometry and incorporation of surface-modified hexagonal boron nitride (h-BN) nanofillers. In this research, the curing agent concentration for pure EP is optimized first based on high thermal stability and sufficiently reliable electrical properties. Second, the optimized pure EP is used as a base material to prepare epoxy/h-BN nanocomposites. Various physicochemical, thermal, and electrical characterizations are performed to analyze the properties of prepared materials. Results show that the higher curing agent concentrations offer a good balance between the thermal and electrical performance of the EP. However, the HF and HT stress exhibits detrimental effects on the breakdown strength and dielectric properties of the materials. Also, the addition of nanofillers further enhances the thermal properties while exhibiting sufficient electrical properties. By the control of resin stoichiometry and nanofiller addition, suitable composites for the HF and HT environment can be realized. [ABSTRACT FROM AUTHOR]

In this paper, a modification method of polypropylene (PP) films is proposed for capacitors by micro doping of carboxylated cellulose nanocrystals (C-CNCs). Results prove that crystallization process of films is promoted, due to the entanglement effect of acicular ultra-structures of C-CNCs on PP molecular chains. With a proper doping content (0.01 wt%), the thermal properties are elevated, and the DC conductivity decreases by raising crystallinity and limiting carrier movement. Modified films possess a restricted dielectric loss at low frequencies because of regular microstructures and decreased conduction loss. Based on DC experiments at different temperatures, the breakdown strength of C-CNC/PP films shows an increase by approximately 51% at 85 °C, basically equaled to the level of pure PP at 25 °C. The mechanism is attributed to deep trap sites, which are introduced by the large crystal region and result in short free path in carrier transport. This novel PP film shows a great potential for application under thermal-electrical compound field in power systems. [ABSTRACT FROM AUTHOR]

This article proposes an analytic coupled magneto-thermal analysis of an axial-flux (AF) permanent-magnet-assisted (PMA) eddy-current brake (ECB) at high-temperature working conditions. In the topology investigated, permanent magnets (PMs) are placed into stator slot openings to increase the braking torque production capability. This modification enables to control the magnet flux by altering the dc excitation current. However, the utilization of PMs will make the construction vulnerable at high operating temperatures simply because the magnet properties and the brake capability are strongly dependent on temperature. Such problems require complex coupled multiphysics finite-element analyses to obtain the actual brake performance. The proposed approach offers a simple and effective solution that consists of magnetic and thermal models, which are coupled to each other in the time domain. The nonlinear electrical, magnetic, and thermal properties are influenced by the temperature variation in time. An AF-PMA-ECB prototype is manufactured to validate the proposed coupled models and the experimental studies confirm that the proposed approach provides very practical results to determine the working conditions of the AF-PMA-ECB at high-temperature operations. [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]

To suppress space charge accumulation and minimize the antioxidant migration, polyethylene (PE) grafted with reactive hindered amine antioxidant MC prepared by melt radical grafting is investigated in this work. Fourier transform infrared spectroscopy is used to investigate the grafting reaction, which shows that the antioxidant MC is successfully introduced onto PEe Space charge distribution, DC conductivity, DC breakdown strength and thermally stimulated current are measured and the electronic structure is calculated from first-principles. The results show that PE grafted with antioxidant MC can effectively suppress space charge accumulation, reduce DC electrical conductivity and enhance DC breakdown strength. The polar functional groups of antioxidant MC anchored on PE macromolecular chain form immobile deep traps at the grafted MC sites, which can capture space charges and scatter charge carriers to reduce the amount, mobility and energy of charge carriers. Seen from the oxidative induction time of the specimens before and after acetone extraction, the level of retention of the grafted antioxidant MC are significantly higher than those of conventional antioxidant 300 and antioxidant 4020, which indicates that PE grafted with antioxidant MC has excellent long-term thermal oxidation stability. [ABSTRACT FROM AUTHOR]

In this work, we analyze the impact of self-heating effects (SHEs) on 14-nm negative capacitance (NC)-FinFET performance from device to the circuit level. The 3-D thermal TCAD simulations, after careful calibration with measurements, are performed to analyze the impact of SHE in a broad range of frequency. Furthermore, we use the TCAD calibrated BSIM-CMG model to analyze the impact of SHE in NC-FinFET at the circuit level, after including a physics-based model to capture the NC effect. For the first time, we analyze the impact of a nonuniform distribution of temperature dissipated from the channel region to gate-stack in NC-FinFETs. On account of the thermal insulating properties of the gate-stack, the ferroelectric (FE) layer is found to be cooler than the channel region under the impact of SHE. We demonstrate that neglecting that and, hence, using the channel temperature to evaluate the temperature-dependent parameter α (in the Landau–Khalatanikov model of NC effect) of the FE layer result in a significant overestimation of SHE-induced degradations, such as in the NC voltage gain. Based on our TCAD analysis, we propose a relation between gate-stack temperature and the channel temperature and use this to accurately model the α parameter and, hence, SHE in NC-FinFETs. The SHE is found to dominate for both FinFET and NC-FinFET in the gigahertz range, which eventually degrades the performance at the circuit level, which is further confirmed using ring oscillator (RO) simulations. [ABSTRACT FROM AUTHOR]

The traditional cup-shaped LED packaged with epoxy molding compound materials (EMC-LED) and chip-scale packaged LED (CSP-LED) were prepared and analyzed in this article. It is found that high temperature can result in the spectrum red shift and the photoelectric performance degradation for these LEDs due to the degradation of chip and packaging materials. Compared with EMC-LED, the CSP-LED device has a lower thermal resistance of 3.31 °C/W due to the shorter thermal dissipation path and has better stability under the different temperature and drive current conditions. All the simulation results agree well with experimental and theoretical results, indicating that the photoelectric and thermal properties of the CSP-LED can be improved by introducing ceramic substrate and optimizing the material of the interconnected surface and the size of the conduction area. These results have guiding significance for the future CSP-LED design and application. [ABSTRACT FROM AUTHOR]

Objective: Tissue electroporation is achieved by applying a series of electric pulses to destabilize cell membranes within the target tissue. The treatment volume is dictated by the electric field distribution, which depends on the pulse parameters and tissue type and can be readily predicted using numerical methods. These models require the relevant tissue properties to be known beforehand. This study aims to quantify electrical and thermal properties for three different tissue types relevant to current clinical electroporation. Methods: Pancreatic, brain, and liver tissue were harvested from pigs, then treated with IRE pulses in a parallel-plate configuration. Resulting current and temperature readings were used to calculate the conductivity and its temperature dependence for each tissue type. Finally, a computational model was constructed to examine the impact of differences between tissue types. Results: Baseline conductivity values (mean 0.11, 0.14, and 0.12 S/m) and temperature coefficients of conductivity (mean 2.0, 2.3, and 1.2 % per degree Celsius) were calculated for pancreas, brain, and liver, respectively. The accompanying computational models suggest field distribution and thermal damage volumes are dependent on tissue type. Conclusion: The three tissue types show similar electrical and thermal responses to IRE, though brain tissue exhibits the greatest differences. The results also show that tissue type plays a role in the expected ablation and thermal damage volumes. Significance: The conductivity and its changes due to heating are expected to have a marked impact on the ablation volume. Incorporating these tissue properties aids in the prediction and optimization of electroporation-based therapies. [ABSTRACT FROM AUTHOR]

The relevance of anisotropic heatsinks for heat-assisted magnetic recording (HAMR) is investigated. First, 3-D thermal modeling is used to demonstrate that the heatsink performance on a glass substrate is determined by the heatsink in-plane thermal conductivity. The out-of-plane thermal conductivity has almost no impact on the heatsink ability to carry heat away from the hot spot. As a result, an anisotropic heatsink can be a good alternative to some conventional isotropic heatsink materials when its in-plane thermal conductivity is larger than that of the isotropic material. Second, time-domain thermo-reflectance (TDTR) measurements are presented to extract both the in-plane and the out-of-plane thermal conductivities of a (Cu/Ta) multilayer heatsink. The sensitivity to in-plane thermal conductivity is achieved by using small laser beam sizes and by combining measurements at multiple modulation frequencies on both a low and a high thermally conductive substrate. The fitting of all TDTR spectra gives for the (Cu[5.1]/Ta[1.4]) multilayers an effective out-of-plane thermal conductivity of 11.5 W/mK and an in-plane thermal conductivity of 69 W/mK. These thermal properties make such multilayer material an interesting candidate as HAMR heatsink, equivalent to a 70 W/mK isotropic material. [ABSTRACT FROM AUTHOR]

The output characteristics of vertical cavity surface emitting lasers (VCSELs) arrays are largely influenced by temperature. We systematically studied thermal properties in 20-element oxide-confined VCSEL arrays via both theory and experiment. The output power, conversion efficiency, and threshold current dependent on ambient temperatures were measured. According to the relationship of wavelength shift and dissipated power, the device thermal resistance dependent on ambient temperature was obtained. The actual temperature in active region was successfully extracted. A 3-D heat diffusion model was established to simulate temperature distribution accurately. [ABSTRACT FROM AUTHOR]

In this article, the problem of modeling the thermal properties of the IGBT using a nonlinear compact thermal model is considered. This model has the form of an electrical network. In the proposed model, the influence of the internal temperature of this transistor on the efficiency of heat dissipation is taken into account. The elaborated model form is presented and the estimation method of this model parameters is described. The correctness of the new model is verified experimentally for different cooling conditions and different values of ambient temperature. Additionally, some results of calculations are compared to the results of calculations performed using selected models given in the literature. [ABSTRACT FROM AUTHOR]

Research on material characterization has received an increasing amount of attention recently. In several application scenarios, it is essential to effectively estimate the physical properties of objects without coming into contact with them (e.g., tele-operated or autonomous robotics). This article presents the Haptic Eye: a framework using active thermography that uses a custom multichannel neural network approach to perform classification between samples and regression toward their thermal properties. This neural network structure is uniquely suited for effective processing of thermographic data. The framework is realized, implemented, and evaluated with a set of ten samples with diverse thermal/physical properties. Experimental results on a realization of the framework validate this approach, with a 92.20% classification accuracy using multichannel neural network with majority vote, as well as more than 99.6% R2-fit with respect to three different thermal properties, namely thermal conductivity, thermal diffusivity, and thermal effusivity (which is very useful to define thermal exchange during physical interaction). [ABSTRACT FROM AUTHOR]

In this article, we propose a 2-D study for investigating the self-heating effect in new partially insulated field-effect transistors (PiFETs) based on high-k gate dielectrics. The thermal properties have been numerically simulated and compared to those of conventional bulk-metal–oxide–semiconductor field-effect transistor (bulk-MOSFET) and PiFET structures. Several high-k materials such as ZrO2, HfO2, La2O3, and Al2O3 are used in order to test their impact on the temperature rise in the host lattice of new structures. A deal of interest has been paid to geometric parameters in the PiFET structures studied to further reduce the self-heating. The effects of geometrical and electrical parameters have been analyzed. As it is found, a significant reduction in temperature rise is achieved during high-power operation. This suggests that the insertion of high- k dielectric layers above the dioxide can mitigate the self-heating. More especially, Al2O3 has been revealed as an appropriate high-k dielectric to being recommended for the production of high-performance PiFET. [ABSTRACT FROM AUTHOR]

Modern aircraft have an increasing need for pulse power loads which includes new weapon technologies and advanced avionics. These pulse power loads have thermal properties that couple to the electrical system and can lead to nonlinear destabilizing effects at low and high temperatures. These nonlinear electrical stability issues carry through to the mechanical and thermal systems of the aircraft and can damage components. The load is characterized by its duty cycle, period, and power level. For a given pulse load, the system is defined as metastable if there is a nonlinear limit cycle that remains bounded within the defined bus voltage limits. Regions of stability, metastability, marginal metastability, and instability are determined based on bus voltage transient tolerances. In this article a reduced-order nonlinear model of an aircraft's coupled electrical-mechanical-thermal (EMT) system is used to demonstrate the stability, metastability, and performance caused by the pulse load coupled with the EMT system. [ABSTRACT FROM AUTHOR]

The design for the reliability of automotive electronics involving viscoelastic materials requires accurate knowledge of material properties under critical frequency and temperature conditions. Both forward and inverse approaches for the dynamic characterization of a soft silicone-based thermal interface material used in electronic control units are presented and discussed. The classic forward characterization implying dynamic mechanical analysis and the principle of time–temperature superposition is applied in a first step. The identified material model under critical temperature conditions is restrained to a narrow frequency range and a validation for higher frequencies is needed. The proposed inverse method presented in the second part minimizes the residue between the measured and numerical transfer functions of single-lap joint specimens at chosen control frequency ranges located at the resonances of the structure. The specimens are excited by an electrodynamic shaker situated in an environmental chamber allowing measurements under different temperature conditions. The main outcome of the inverse approach is a validation of the results of forward characterization for a broad frequency range and under critical temperature conditions adopting a simple experimental arrangement and a barely complex numerical procedure. [ABSTRACT FROM AUTHOR]

Photosensitive polymers or dielectric materials such as polyimides (PIs) have been used in fan-out wafer-level packaging process (FOWLP) as a redistribution layer for quite some time. In the condensed 2-D and 3-D packaging processes, the dielectric materials are applied multiple times to create as many as four or five redistribution layers. At the end of the process, the first layer may experience up to four times of heat cycles in which the polymer properties may change. However, the effect of heat cycles on properties of dielectric film as well as their contributions to the wafer-level warpage is still unclear. To understand the changes of materials’ properties after several heat cycles, the thermal and thermo-mechanical properties of negative-tone and positive-tone types of dielectric films are characterized by using the thermomechanical analysis (TMA), dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). The glass transition temperature (${T}_{g}$), coefficient of linear thermal expansion (CTE), and modulus (storage, ${E}'$ , and loss, ${E}''$) are analyzed and compared. In addition, the morphology of the films before and after heat cycles is also analyzed. [ABSTRACT FROM AUTHOR]

Better mechanical, thermal properties and longer lifetimes are needed for the die attach layer in high-power electronic packaging. As traditional Sn–Ag–Cu (SAC) solders have many limitations, the sintered nanosilver materials are becoming one of the substitutes for high-power electronic packaging. However, the high performance of sintered nanosilver materials is only achieved when its fine sintering densification is formed. This article investigates the sintering densification process of nanosilver particles based on the design of orthogonal experiments and sintering kinetics modeling in which both the macroproperties and micromorphology are linked and analyzed. The results lead to several conclusions, such as: 1) the orthogonal experiments consider the effects of sintering temperature, dwell time, and sample preparation pressure on the sintering relative shrinkage and relative density—the results show that the most critical impact factor on sintering densification is the sintering temperature. (2) In the sintering kinetic experiments, the sintering densification rates obtained by fitting the relative density versus dwell time curves during 175 °C–250 °C follow the Arrhenius model, and the apparent activation energy of sintering kinetics is calculated to be 36 kJ/mol, while it is calculated from the particle size is 38.1 kJ/mol. 3) Through modeling the relationship between particle size, line shrinkage, and porosity, the line shrinkage and porosity first increase at the initial stage, while the particle size increases, and the macroscopic volume decreases at the end of sintering, the porosity decreases. [ABSTRACT FROM AUTHOR]

This article presents an electric-based methodology for thermal characterization of semiconductor technologies. It is shown that for technologies such as gallium nitride (GaN) high electron mobility transistors, which exhibit several field induced electron trapping effects, the thermal characterization has to be performed under specific conditions. The electric field is limited to low levels to avoid activation of trap states. At the same time, the dissipated power needs to be high enough to change the operating temperature of the device. The method is demonstrated on a test structure implemented as a GaN resistor with large contact separation. It is used to evaluate the thermal properties of samples with different silicon carbide suppliers and buffer thickness. [ABSTRACT FROM AUTHOR]

As the speed gap of the modern processor and the off-chip main memory enlarges, on-chip cache capacity increases to sustain the performance scaling. As a result, the cache power occupies a large portion of the total power budget. Spin transfer torque magnetic memory (STT-MRAM) is proposed as a promising solution for the low power cache design due to its high integration density and ultralow leakage power. Nevertheless, the high write power and latency of STT-MRAM become new barriers for the commercialization of this emerging technology. In this paper, we investigate the thermal effect on the access performance of STT-MRAM, and observe that the temperature can affect the write delay and energy significantly. Then, we explore the nonuniform cache access (NUCA) design of the chip-multiprocessors with STT-MRAM-based last level cache (LLC). A thermal aware data migration policy, called “Thermosiphon,” which takes advantage of the thermal property of STT-MRAM, is proposed to reduce the LLC write energy. This policy splits the LLC into different regions dynamically based on the thermal distribution monitored by thermal sensors available on-chip, and adaptively migrates write intensive data among different thermal regions considering the thermal gradient. Compared to the conventional NUCA design, our proposed design can save 41.2% write energy at most and 13.01% on average with negligible hardware overhead. [ABSTRACT FROM AUTHOR]

This work investigates the effect of graphene filler in epoxy resin with the purpose of developing an improved thermally conductive epoxy encapsulation material for electronic devices. The findings in this work show that the thermal conductivity increases by a factor of about 1.6 times with 0.1 wt% loading of graphene in epoxy resin. The increase in the rate of surface charge verifies an improved anti-static property. On examining the phase resolved partial discharge patterns, it is observed that the inception voltage and the number of partial discharge pulses is lower for the filled epoxy compared to that of the neat epoxy. The increase in the rate of surface charge decay indicates an improved anti-static property. The findings in this paper provide a reference in the development of materials with improved thermal conductivity and anti-static properties for graphene/epoxy materials for use in the packaging of electronic devices. [ABSTRACT FROM AUTHOR]

Polypropylene (PP)-based composites including PP/thermoplastic polyolefin (TPO) elastomer blends and PP/TPO-based nanocomposite are rather promising insulation materials for HVDC cables. Aging is an inevitable issue in practical operation and needs to be investigated thoroughly. In this paper, PP/TPO blends and PP/TPO/ZnO nanocomposite were prepared and thermally aged at 130 °C for various periods (28 days at longest). The micro-morphology, thermal properties and high-temperature space charge behavior were investigated. The results show that PP and TPO still exhibited excellent compatibility without phase separation after thermally aging. The crystallinity was not influenced after thermally aging, but a new endothermic peak at about 140 °C appeared in the melting process of thermally aged composites. Space charges accumulated in the two thermally aged composites, but dissipated slowly in PP/TPO, while dissipated rapidly first and then reduced in PP/TPO/ZnO nanocomposite. The calculated apparent charge mobility and trap level distribution based on space charge dissipation show that deep traps increased in aged PP/TPO, but decreased in aged PP/TPO/ZnO nanocomposite, which may be correlated with the chemical variation of thermally aged polymer matrix. The work may give a reference on the aging research of PP-based composite material for recyclable HVDC cable insulation. [ABSTRACT FROM AUTHOR]

This study introduces silicone elastomers with micro and nano-sized boron nitride (BN) and silicon carbide (SiC) particles with various doping levels to improve thermal properties and partial discharge resistance. The effect of micro and nano-fillers on thermal conductivity, coefficient of thermal expansion (CTE), and thermal stability are investigated. Polarization and depolarization current and partial discharge are measured to investigate the non-linear conductivity, trap energy density distribution, and partial discharge resistance. Experimental results show higher thermal conductivity, lower CTE, and better thermal stability than the original silicone elastomer. Large size fillers dominate the thermal conductivity when the doping level is low, whereas the composite microstructure plays a significant role in the thermal conductivity when the doping level is high. The combination of different filler type and size has less effect on thermal stability and CTE compared to the effect of the doping level. According to the depolarization current, the composite's trap depth is generally shallower than that of the original silicone elastomer. With increased doping level, the shallow trap density increases, providing hopping sites for carriers, whereas the deep trap density decreases, reducing the number of trapped charges. The partial discharge inception voltage is higher than that of the original silicone elastomer, and it increases with the doping level, which may be because the electrostatic field generated by diffused charges reduces the local electric field near the high voltage electrode. [ABSTRACT FROM AUTHOR]

With the growing interest in electrification and as hybrid and pure electric powertrains are adopted in more applications, electrical machine design is facing challenges in terms of meeting very demanding performance metrics, for example, high specific power, and harsh environments. This provides clear motivation to explore the impact of advanced materials and manufacturing on the performance of electrical machines. This article provides an overview of additive manufacturing (AM) approaches that can be used for constructing electrical machines, with a specific focus on additively manufactured iron core, winding, insulation, and permanent magnet, as well as cooling systems. Since there has only been a few attempts so far to explore AM in electrical machines (especially when it comes to fully additively manufactured machines), the benefits and challenges of AM have not been comprehensively understood. In this regard, this article offers a detailed comparison of multiple multimaterial AM methods, showing not only the possibility of fully additively manufactured electrical machines but also the potential significant improvements in their mechanical, electromagnetic, and thermal properties. The articles will provide a comprehensive discussion of opportunities and challenges of AM in the context of electrical machines. [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 increase in voltage level and compactness of electrical equipment result in demands for electrical insulations that have high breakdown strength, high thermal conductivity, and high electrical resistivity. Use of dielectric polymer nanocomposites is a promising approach that has great advantages over the traditional materials. This article explores the influence of alumina nanofillers, both treated and untreated, on properties of silicone rubber-based nanocomposites. Composite samples made of 10 wt% and 20 wt% filler loading are prepared using high shear (HS) and electrostatic disperser (ES) techniques with the aim of achieving maximum dispersion of fillers in the silicone matrix. Effects of filler type, filler concentration and mixing method on morphological changes, thermal, erosion, and electrical properties are analyzed. Scanning electron micrographs (SEMs) showed better filler dispersion in composites prepared using ES than using HS mixer. Thermogravimetric analysis and thermal conductivity measurements revealed enhanced thermal stability and conductivity with increasing filler loadings. Additionally, ES composites showed high erosion resistance. Composites containing treated alumina performed better than those containing untreated alumina. In total, composites prepared with treated alumina using the ES method showed marked improvement in thermal properties and erosion resistance due to homogeneous filler dispersion imparting high number of filler-matrix interfaces and stronger bonding as visualized from SEMs and dielectric spectroscopy data. [ABSTRACT FROM AUTHOR]

In this paper, the problem of how to describe the thermal properties of the insulated-gate bipolar transistor (IGBT) module with the use of the compact thermal model is considered. This model makes it possible to calculate internal temperature of every semiconductor device included in this module with self-heating phenomena and mutual thermal couplings between these devices taken into account. A new method of measuring parameters of the thermal model of devices contained in the considered module is proposed, and the accuracy of this method is discussed. Some results of measurements of the considered parameters are presented, and uneven distribution of temperature in the investigated module in selected conditions of its power supply is evaluated. Differences between the measured waveforms of the internal temperature of components of the IGBT module and its casings are discussed. [ABSTRACT FROM AUTHOR]

We report on the first experimental demonstration of silicon carbide (SiC) microdisk resonators operating in water, featuring robust multimode resonances in the high and very high frequency (HF/VHF) bands. Thanks to its excellent mechanical, optical, thermal properties and biocompatibility, SiC is particularly attractive for physical, chemical, and biological applications in liquid. Compared with the prevailing device structures in beams and cantilevers, disk resonators offer larger capturing surfaces at the same length scale and greater flexibility in accessing their richer multimode responses, which can be harnessed for enhancing the mass sensing performance in liquid. In this paper, we design and fabricate SiC microdisks and experimentally characterize their multimode resonances in both air and water. We observe up to 28 flexural modes within ~ 5–200 MHz and quality ($Q$) factors as high as ~ 1050 in air, as well as 12 modes within ~3–190 MHz and $Q\text{s}$ up to ~ 30 in water. These metrics are the highest among the reported flexural-mode micromechanical resonators operating in liquid. We further demonstrate the detection of single microparticle in water using the SiC microdisks and investigate the position-dependent multimode responses by combining laser interferometry and optical tweezering techniques. We observe multimode frequency shifts in response to single silica microbead loading, with mass responsivity up to ~ 120 Hz/fg. This SiC multimode resonator platform may help advance in-liquid particle sensing and biological measurement applications. [2018-0259] [ABSTRACT FROM AUTHOR]

This paper introduces a new nonlinear multidisciplinary design approach (NMDA) for axial-flux (AF) eddy current brakes (ECBs). The proposed NMDA is developed by nonlinear magnetic–thermal–structural coupled modeling. The nonlinear behaviors of the AF-ECB covering the BH curve, resistivity, heat capacity, thermal conductivity, and the temperature are jointly analyzed in time domain to investigate the actual brake properties and to determine brake operating range. In this paper, the nonlinear magnetic modeling based on two-dimensional (2-D) reluctance network is studied by a modified Newton–Raphson method. Furthermore, the nonlinear thermal modeling is carried out by lumped-parameters considering the change of heat capacity, thermal conductivity, and the temperature and updating the data in the evaluation process. Finally, the nonlinear structural modeling is performed to obtain the deflection and the mechanical safety factor of the brake. The nonlinear modeling methods in the proposed NMDA are validated by independent 3-D electromagnetic, thermal, and structural finite element analyses (FEAs), and the proposed NMDA is tested with two different AF-ECB prototypes. The experimental results confirm that the proposed NMDA has high accuracy, and compared to 3-D-FEA approaches, it provides a fast solution to predict the AF-ECB performance. [ABSTRACT FROM AUTHOR]

Addition of alumina nano particles to silicone rubber (SR) has shown a significant improvement in electrical, mechanical and thermal properties of the SR nanocomposites. Static contact angle and water droplet-initiated corona inception voltage exhibited a marginal change on inclusion of nano alumina into SR matrix. Alumina filler improved the corona ageing resistance of the composites; however, a marginal reduction in the rate of hydrophobicity recovery is observed. Laser induced breakdown spectroscopy proved as an effective tool to rank the performance of the SR nano composites. Variation of crater depth with energy of laser pulse and number of laser pulses follows the exponential relation. Plasma temperature calculated by optical emission spectroscopy is in line with the amount of damage caused to the surface of the specimen by water droplet-initiated discharge. Dielectric response spectroscopic studies indicate that inclusion of nano fillers has resulted in lower interfacial polarization and lower imaginary permittivity. It is observed through dynamic mechanical analysis that the composites have higher storage modulus and the activation energy compared to base SR. [ABSTRACT FROM AUTHOR]

Junction temperature is an important parameter for evaluating thermal property of light-emitting diodes (LEDs). How to accurately measure the junction temperature still remains controversial. In this paper, we propose a continuous rectangular-wave method (CRWM) for measuring the junction temperature of LEDs. This method uses a continuous rectangular wave to drive LED under either voltage mode or current mode, and acquires the transient voltage response, i.e., the heating curve, by a high-definition oscilloscope at the rising edge of each cycle. Compared with the conventional forward voltage method (FVM), where a switch is necessary to transit the heating state to the sensing state and a transient cooling curve is usually acquired, the switch-free-periodic-acquisition CRWM avoids the acquisition time delay caused by switch and decreases charging/discharging effect of LEDs effectively with rising time of the rectangular wave less than 40 μs. Besides, periodic acquisition of the heating curve further enhances the signal-to-noise ratio. Comparative experiments by FVM, CRWM, and micro-thermocouple show coincidence and accuracy of CRWM with relative error less than 3% in current mode and 1.5% in voltage mode. COMSOL simulation is applied to verify the validity of CRWM and discuss the impact of rising time of the rectangular wave. [ABSTRACT FROM AUTHOR]

We have developed a new portable, ground-based imaging system primarily to investigate the thermal properties of volcanic processes during lava propagation and cooling, although it is potentially applicable to any dynamic geologic process. The miniature multispectral thermal camera (MMT-Cam) is an imaging system that acquires six wavelength bands of thermal infrared (TIR) data between 8 and $12~\mu \text{m}$ nearly simultaneously. The spatial and temporal resolutions of the camera system are high, $640 \times 512$ pixels, and 1 s, respectively. The imaging system is calibrated using full-aperture blackbody experiments at a range of temperatures from 283 to 1023 K to account for all instrumental, optical, and transmission effects. In addition, the baseline drift due to changing internal camera temperature is measured and removed. As a result, the accurate multispectral TIR image data are acquired of dynamic surfaces such as propagating and cooling lava flow surfaces captured at the critical temporal (seconds) and thermal (initial rapid cooling) scales. These improved acquisition parameters provide valuable data for both compositional and textural spatiotemporal variability analyses of these volcanic surfaces. Furthermore, the MMT-Cam specifications are designed to be comparable to current and proposed Earth-orbiting TIR instruments to better evaluate the potential for future TIR data sets to deliver similar data sets. [ABSTRACT FROM AUTHOR]

Arc ablation during the operation of HVDC circuit breakers can cause irreversible damage to the epoxy resin (EP) insulation pull rod. This is one of the critical factors that affect the reliability and lifetime of a HVDC circuit breaker. In this work, we built an arc ablation experimental platform and studied the thermal response properties of EP insulation under arc ablation. The surface charge evolution characteristics and the dielectric properties were analyzed to reveal the underlying surface insulation failure mechanism of EP after arc ablation. The results indicate that arc ablation can cause severe carbonization to EP insulation. With increasing arc duration, the EP gradually transforms into carbide and pore products. Arc ablation can decrease the molecular moment orientation polarizability and the relative dielectric constant of EP insulation, and thereby increasing the current density formed by Schottky injection. Therefore, when the external electric field is applied, the charge on EP insulation surface migrates from high voltage electrode to the ablating area, causing the regional accumulation of surface charge and the formation of local failure area. This can decrease the surface electrical performance of EP insulation and lead to insulation failure finally. [ABSTRACT FROM AUTHOR]

Research on material characterization has received an increasing amount of attention recently. In several application scenarios, it is essential to effectively estimate the physical properties of objects without coming into contact with them (e.g., tele-operated or autonomous robotics). This article presents the Haptic Eye: a framework using active thermography that uses a custom multichannel neural network approach to perform classification between samples and regression toward their thermal properties. This neural network structure is uniquely suited for effective processing of thermographic data. The framework is realized, implemented, and evaluated with a set of ten samples with diverse thermal/physical properties. Experimental results on a realization of the framework validate this approach, with a 92.20% classification accuracy using multichannel neural network with majority vote, as well as more than 99.6% R2-fit with respect to three different thermal properties, namely thermal conductivity, thermal diffusivity, and thermal effusivity (which is very useful to define thermal exchange during physical interaction). [ABSTRACT FROM AUTHOR]