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Interferences, characteristic for non-destructive thermal testing which reduce the reliability of the results obtained are described. A technique for their reduction is suggested which consists of two interrelated stages. The first stage consists in calculating and analyzing the nature and level of the expected signal according to the developed thermophysical model against the background of the experimentally obtained noise level. According to the results of analysis of calculations using the thermophysical model for the selected samples, the most influential interference was the inhomogeneity of the emissivity of the sample surface. The second stage of processing the received data is devoted to reducing this noise. This stage consists in processing of thermograms of temperature fields and includes morphological analysis of the surface condition, filtering and reducing characteristic noise and interference. It consists of four practical procedures: analysis of the visual image and obtaining a map of zones with different emissivity of the sample surface, analysis of the thermogram with an assessment of the level of discreteness of the thermogram and the position of fiducial points on the image, smoothing the thermographic image and highlighting zones on the thermogram with different emissivity of the controlled object surface, after which the noise is filtered. Since the results of thermal control are strongly influenced by the shape of the object, the possibilities and effectiveness of the suggested technique are illustrated on a cylindrical object. It has been experimentally confirmed that for the selected sample, it was possible to reduce the noise level to that of confident separation of useful signal against the noise background. [ABSTRACT FROM AUTHOR]

Interferences, characteristic for non-destructive thermal testing which reduce the reliability of the results obtained are described. A technique for their reduction is suggested which consists of two interrelated stages. The fi rst stage consists in calculating and analyzing the nature and level of the expected signal according to the developed thermophysical model against the background of the experimentally obtained noise level. According to the results of analysis of calculations using the thermophysical model for the selected samples, the most infl uential interference was the inhomogeneity of the emissivity of the sample surface. The second stage of processing the received data is devoted to reducing this noise. This stage consists in processing of thermograms of temperature fi elds and includes morphological analysis of the surface condition, fi ltering and reducing characteristic noise and interference. It consists of four practical procedures: analysis of the visual image and obtaining a map of zones with diff erent emissivity of the sample surface, analysis of the thermogram with an assessment of the level of discreteness of the thermogram and the position of fi ducial points on the image, smoothing the thermographic image and highlighting zones on the thermogram with diff erent emissivity of the controlled object surface, after which the noise is fi ltered. Since the results of thermal control are strongly infl uenced by the shape of the object, the possibilities and eff ectiveness of the suggested technique are illustrated on a cylindrical object. It has been experimentally confi rmed that for the selected sample, it was possible to reduce the noise level to that of confi dent separation of useful signal against the noise background. Ref. 10, Fig. 5. [ABSTRACT FROM AUTHOR]

Wire electric discharge machining (WEDM) is one of the most important non-traditional manufacturing methods and widely utilized in aerospace and tooling industry. However, the lack of the accurate numerical description of the WEDM process impedes a better understanding of the WEDM process and its machining mechanism. Since the vibration of the wire significantly affects the discharge location and the temperature distribution of the workpiece, the thermophysical model of the WEDM is much more complex than that of the EDM. In this paper, based on the classical thermal model of the EDM, a novel finite element method (FEM) model of WEDM considering the three dimensional wire vibration was proposed to simulate the machining process and verified by a series of WEDM experiments. Eventually, the effects of the wire vibration on the material removal rate and recast layer thickness were investigated quantitatively by analyzing the simulation results of this new thermophysical model and corresponding experimental results. [ABSTRACT FROM AUTHOR]

Dwarf planet Ceres is characterized by several sites hosting (or have hosted) ice‐rich patches as revealed by the Dawn's Visible and InfraRed spectrometer. The study of the illumination conditions including the effects of the local topography become critical in the estimation of the ice lifetime as well as the water vapor production rate. In this work we applied a 3‐D thermophysical model in order to study the illumination conditions on the shape model, derived on the basis of the images acquired by the Dawn's Framing Camera during the Survey mission phase, and to calculate the surface temperatures and water sublimation rates. We are interested in a crater in the northern hemisphere (42°), Oxo, which hosts water ice in its southern wall. A comparison with the surface temperatures and water sublimation rates of another Ceres' crater, Juling, is carried out. Water ice sublimation rate of its ice‐rich patch suggests that the Oxo crater probably is not the source of the emission detected by Herschel, a source that could be represented instead by the Juling crater. Plain Language Summary: There are several reasons to support the idea that the dwarf planet Ceres is a world with a huge presence of water. First of all, spectral evidence of water ice has been revealed by the Dawn's Visible and InfraRed spectrometer on the wall of some craters. Furthermore, both geomorphological evidence like surface flows and the presence of minerals, whose origin is correlated to the aqueous alteration, support this idea. Numerical simulations could contribute to understand how long the ice is stable on the surface, by studying the illumination conditions, and quantifies the eventual sublimation rate. In this work we concern about a particular crater, Oxo, in the northern hemisphere at latitude 42°, which hosts an ice‐rich patch in the southern wall. Key Points: We calculated the surface temperature and sublimation rates of Oxo crater by applying a 3‐D thermophysical model on real topographyWe compared the simulated temperatures with the VIR measurementsWater emission rate suggests that Oxo is not the source of the emission detected by Herschel, while Juling probably is the best candidate [ABSTRACT FROM AUTHOR]

Ice thermal stability on the surface of the dwarf planet Ceres is an important issue linked to the Herschel observations of water vapor around Ceres. One of these surficial ice deposits is located within the 20‐km crater Juling (35°S, 168°E). The study of water ice exposure in this specific crater is particularly interesting because it has been observed that the water ice abundance changes on a time scale of a few months. To understand the ice behavior, we applied a 3‐D finite element method thermophysical model to the study of Juling crater in order to determine the water ice sublimation rate. We use a detailed shape model of Ceres derived from optical imagery returned by the Framing Camera on board Dawn. We explore the effects of different heliocentric distances and different thermal inertia values, comparing our numerical predictions with the observational evidences returned by VIR and by the Herschel Space Observatory. Plain Language Summary: Ceres is a dwarf planet of the solar system with a significant amount of water both in its interior and in the surface layers. A crater in the southern hemisphere, Juling, is characterized by the presence on its surface of a mixture of ice and rocks as revealed by recent VIR data from the Dawn spacecraft. This crater is a good place to preserve ice since it is poorly illuminated, particularly in the northern wall. Most important is the detection of ice variations on its wall during the Dawn visible and infrared mapping spectrometer observations. In this work we performed numerical simulations in order to evaluate temperatures and water ice sublimation rate, assuming reasonable values for the physical parameters, and to estimate the longevity of ice on the surface of Ceres. Key Points: Ice stability on the surface of the crater Juling is an issue closely related to the Herschel observations of water vapor around Ceres.We apply a 3-D thermophysical model with real topography in order to evaluate the surface temperatures and the ice sublimation ratesJuling northern wall, due to its faint solar illumination, results to be a good place to host water ice [ABSTRACT FROM AUTHOR]

Microgrinding is a promising machining method for high-precision microcomponents, but only experimental models of the process exist as yet. Theoretical simulation of the process is required in order to develop technology on the basis of microgrinding. In the present work, we develop a thermophysical model of the process. [ABSTRACT FROM AUTHOR]

The study of the temperature field of power semiconductor devices, operating in semiconductor apparatuses, either non-contact or hybrid was carried out in the paper. It was also shown that the main mode of the current load of power semiconductor devices, operating in semiconductor apparatuses is a pulse mode. Analytical method for calculating the values of the temperature rise in the structure of power semiconductor devices when subjected to a current pulse of arbitrary shape based on a model that adequately reflects the design of semiconductor devices was used during the studies. To calculate the thermal mode of power semiconductor devices, a technique, based on using the simplified thermal models, where the solder layers are taken into account due to expansion of thermal-resistance equivalent tungsten layers is also used. However, unlike it, the method, proposed in the paper provides a higher accuracy in calculating the temperature rise in the structure of power semiconductor devices since all layers of these devices are taken into account. Also, calculation by this method takes into account the dependence of physical properties of materials of the thyristor components on the change in their temperature. Solving the system of heat conduction equations, set up for the model that adequately reflects the thyristor design, was performed by finite difference method using the implicit scheme. When calculating the transient thermal resistance using the real model for different types of thyristors, difference in its value reaches 5-16 % compared with the calculation using the simplified models. Thus, calculation of the temperature rise in the structure of power semiconductor devices is appropriate to carry out using the proposed method based on a model that adequately reflects the design of these devices. The described calculation method can be used for the rational choice of a power semiconductor device as a basic element of hybrid and non-contact semiconductor apparatuses in systems of their computer-aided design. The paper presents examples of calculating the thermal mode of semiconductor devices for the most common types of semiconductor apparatuses. [ABSTRACT FROM AUTHOR]

Highlights: [•] Using local thermal non-equilibrium model to solve heat transfer of porous media. [•] CH4/H2O mixture is adopted as feeding gas of porous media receiver. [•] Radiative transfer equation between porous strut is solved by Rosseland approximation. [•] Transport and thermophysical models not included in Fluent are programmed by UDFs. [•] Variations of model on thermal performance of porous media receiver are studied. [Copyright &y& Elsevier]

The link between the surface temperature of Mercury and the exosphere sodium content has been analyzed with the help of a thermophysical model giving soil temperatures coupled with an exospheric circulation model. The calculated exosphere abundance is maximum at perihelion when the temperature attains its maximum value. Another maximum is present at the perihelion; at this moment the temperature is lowest, and this secondary maximum can be explained with a mix of source, loss and transport processes. • The link between the surface temperature of Mercury and the exosphere sodium abundance has been analyzed. • A thermophysical model is being used coupled with an exospheric circulation model. • The exospheric sodium abundance and distribution is strongly dependent on the surface temperature. [ABSTRACT FROM AUTHOR]

Thermal inertia is a key information to quantify the physical status of a planetary surface; it can be retrieved by comparison between theoretical and observed temperature diurnal profiles. We have calculated the surface temperature for a set of locations on Ceres' surface with a thermophysical model that provides temperature as a function of thermal conductivity and roughness, and we have determined the values of those parameters for which the best fit with the observed data is obtained. The observed temperatures have been retrieved form spatially-resolved data from the Dawn mission. In our previous work [ Rognini et al., 2019], we have found that the average thermal inertia for the overall surface of Ceres is low (from 1 to 15 to 60 ​J ​m−2 ​s−½ K−1), as expected according to the general trend observed in the Solar System for atmosphere-less bodies, while the thermal inertia of the very bright faculae found in the floor of the Occator crater could not be well defined. Using more recently acquired VIR high resolution data we find that the central part of the Cerealia facula displays a thermal anomaly (~ 10 K above the average) compatible with a higher thermal inertia with respect to the surrounding regions, while the Vinalia facula does not display any consequently could have a grain size comparable with the Ceres' surface average. • New high resolution data revealed a thermal anomaly in the center of Cerealia facula. • Higher thermal inertia may be an indicator of higher grain size or cementation. • Faculae are not homogeneous, different evolutionary history may be possible. [ABSTRACT FROM AUTHOR]