Статті в журналах: "Thermal computations"

1

Aithal, S. M. "Charged Species Concentration in Combusting Mixtures Using Equilibrium Chemistry." Journal of Combustion 2018 (October 4, 2018): 1–11. http://dx.doi.org/10.1155/2018/9047698.

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Ionization in flames is of interest in the design and development of modern combustion devices. The identity and concentration of various charged species in reacting mixtures can play an important role in the diagnostics and control of such devices. Simplified chemistry computations that provide good estimates of ionic species in complex flow-fields can be used to model turbulent reacting flows in various combustion devices, greatly reducing the required computational resources for design and development studies. A critical assessment of the use of the equilibrium chemistry method to compute charged species concentration in combusting mixtures under various temperatures, pressures, and thermal disequilibrium conditions is presented. The use of equilibrium chemistry to compute charged species concentrations in propane-air mixtures performed by Calcote and King has been extended. A more accurate computational methodology that includes the effect of negative ions, chemi-ions (H3O+ and CHO+), and thermal nonequilibrium was investigated to evaluate the suitability of equilibrium computations for estimating charged species concentrations in reacting mixtures. The results show that equilibrium computations which include the effects of H3O+ and elevated electron temperatures can indeed explain the levels of ion concentrations observed in laboratory flame experiments under lean and near-stoichiometric conditions. Furthermore, under engine-like conditions at higher temperatures and pressures, equilibrium computations can be used to obtain useful estimates of charged species concentrations in modern combustion devices.

2

Moroz, Dmytro. "MODELING OF MAXIMALLY PARALLEL STRUCTURES OF ALGORITHMS FOR SOLVING THERMAL PROBLEMS." Modern Problems of Metalurgy, no. 24 (March 28, 2021): 98–109. http://dx.doi.org/10.34185/1991-7848.2021.01.10.

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The paper demonstrates the possibility of creating a maximum parallel form of computational algorithms to solve thermal problems and their mapping to the architecture of multiprocessor systems based on solving thermal problems of mathematical physics. It is shown that an effective tool for studying heat and mass transfer problems in metallurgical production could be parallel computing technologies on distributed cluster systems with a relatively low cost and reasonably easily scalable both in the number of processors and in the amount of RAM. Tridiagonal structure systems' parallelization was implemented by a numerical-analytical approach, which predetermined their maximally parallel algorithmic form. That approach is facilitated by the minimum possible implementation time of the developed algorithm on parallel computing systems. Furthermore, during the arithmetic expressions parallel computations, the developed algorithm separates the error in the output data from rounding operations. Thus, the parallelization of tridiagonal systems based on numerical-analytical discretization methods does not impose any restrictions on the topology of the mesh nodes of the computational domain.Furthermore, as applied to the parallel computation of arithmetic expressions, it separates the initial data error from a real PC's rounding operations. That approach eliminates the recurrent structure of computing the sought-for decision vectors, which, as a rule, leads to the round-off errors accumulation. Such a parallel form of the constructed algorithm is maximal and has the shortest possible implementation time of the algorithm on parallel computing systems. The developed approach to parallelizing the mathematical model is stable for various types of input data. It has the most parallel form and is distinguished by the minimum time for solving the problem as applied to multiprocessor computing systems. That is explained as follows. If it is hypothesized that one processor can be assigned to one processor and one processor can be assigned to one node of the computational mesh domain, the computations can be processed in parallel and simultaneously for all nodes of the computational mesh domain. The simulation process was implemented on a PC cluster. It follows from the simulation results analysis that the developed method for solving the heat conduction problem effectively minimizes residuals.

3

Sadrizadeh, Sasan. "Numerical Investigation of Thermal Comfort in an Aircraft Passenger Cabin." E3S Web of Conferences 111 (2019): 01027. http://dx.doi.org/10.1051/e3sconf/201911101027.

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This study presents the results of a pilot numerical study of the thermal comfort in the aircraft passenger cabin. The computations have been performed using the Computational Fluid Dynamics (CFD) technique. The overall thermal comfort at temperatures of 15 °C – 20 °C was discussed based on the PMV (Predicted Mean Vote) and PPD (Predicted Percentage of Dissatisfied) indexes. Results indicate that the air velocity and its direction toward the passengers have a considerable impact on their thermal comfort. However, a small variation in temperature has a limited effect on thermal sensation and thus do not jeopardize the overall thermal comfort.

4

Yan, Yihuan, Xiangdong Li, and Jiyuan Tu. "Effects of manikin model simplification on CFD predictions of thermal flow field around human bodies." Indoor and Built Environment 26, no. 9 (June 7, 2016): 1185–97. http://dx.doi.org/10.1177/1420326x16653500.

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Simplified computational thermal manikins are beneficial to the computational efficiency of computational fluid dynamics simulations. However, the criterion of how to simplify a computational thermal manikin is still absent. In this study, three simplified computational thermal manikins (CTMs 2, 3 and 4) were rebuilt based on a detailed 3D scanned manikin (CTM 1) using different simplification approaches. Computational fluid dynamics computations of the human thermal plume in a quiescent indoor environment were conducted. The predicted airflow field using CTM 1 agreed well with the experimental observations from the literature. Although the simplified computational thermal manikins did not significantly affect the airflow predictions in the bulk regions, they strongly influenced the predicted airflow patterns near the computational thermal manikins. The predictive error of the computational thermal manikin was strongly related to the simplification approach. The computational thermal manikins generated from the surface-smoothing approach (CTM 2) was very close to CTM 1, while the required mesh elements for a stable numerical solution dropped by over 75%. Comparatively, the predictive errors of CTMs 3 and 4 were considerable in the near-body regions. This study has illustrated the importance of keeping the key body features when simplifying a computational thermal manikin. The surface-smoothing-based simplification method was shown to be a promising approach.

5

Boisse, P., A. Gasser, and J. Rousseau. "Computations of refractory lining structures under thermal loadings." Advances in Engineering Software 33, no. 7-10 (July 2002): 487–96. http://dx.doi.org/10.1016/s0965-9978(02)00064-9.

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6

Veyhl, Christoph, Thomas Fiedler, Tobias Herzig, Andreas Öchsner, Timo Bernthaler, Irina V. Belova, and Graeme E. Murch. "Thermal Conductivity Computations of Sintered Hollow Sphere Structures." Metals 2, no. 2 (May 30, 2012): 113–21. http://dx.doi.org/10.3390/met2020113.

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7

Paya, Bernard, Virgiliu Fireteanu, Alexandru Spahiu, and Christophe Guérin. "3D magneto‐thermal computations of electromagnetic induction phenomena." COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 22, no. 3 (September 2003): 744–55. http://dx.doi.org/10.1108/03321640310475164.

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8

Boggs, S., Jinbo Kuang, H. Andoh, and S. Nishiwaki. "Electro-thermal-mechanical computations in ZnO arrester elements." IEEE Transactions on Power Delivery 15, no. 1 (2000): 128–34. http://dx.doi.org/10.1109/61.847240.

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9

Holden, John T. "Improved Thermal Computations for Artificially Frozen Shaft Excavations." Journal of Geotechnical and Geoenvironmental Engineering 123, no. 8 (August 1997): 696–701. http://dx.doi.org/10.1061/(asce)1090-0241(1997)123:8(696).

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10

Ziegeler, Nils J., Peter W. Nolte, and Stefan Schweizer. "Quantitative Performance Comparison of Thermal Structure Function Computations." Energies 14, no. 21 (October 28, 2021): 7068. http://dx.doi.org/10.3390/en14217068.

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The determination of thermal structure functions from transient thermal measurements using network identification by deconvolution is a delicate process as it is sensitive to noise in the measured data. Great care must be taken not only during the measurement process but also to ensure a stable implementation of the algorithm. In this paper, a method is presented that quantifies the absolute accuracy of network identification on the basis of different test structures. For this purpose, three measures of accuracy are defined. By these metrics, several variants of network identification are optimized and compared against each other. Performance in the presence of noise is analyzed by adding Gaussian noise to the input data. In the cases tested, the use of a Bayesian deconvolution provided the best results.

11

Górecki, Paweł, and Krzysztof Górecki. "Methods of Fast Analysis of DC–DC Converters—A Review." Electronics 10, no. 23 (November 25, 2021): 2920. http://dx.doi.org/10.3390/electronics10232920.

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The paper discusses the methods of fast analysis of DC–DC converters dedicated to computer programmes. Literature methods of such an analysis are presented, which enable determination of the characteristics of the considered converters in the steady state and in the transient states. The simplifications adopted at the stage of developing these methods are discussed, and their influence on the accuracy of computations is indicated. Particular attention is paid to the methods of fast analysis of DC–DC converters, taking into account thermal phenomena in semiconductor devices. The sample results of computations of the DC–DC boost type converter obtained with the use of the selected methods are presented. The scope of application of particular computation methods and their duration times are discussed. Computations were performed with the use of SPICE and PLECS.

12

Pitot, Samuel, and Nicolas Alborghetti. "ICONE15-10190 COUPLED FULLY 3D NEUTRON KINETICS THERMAL-HYDRAULIC COMPUTATIONS FOR DNB ANALYSIS ON PWRS." Proceedings of the International Conference on Nuclear Engineering (ICONE) 2007.15 (2007): _ICONE1510. http://dx.doi.org/10.1299/jsmeicone.2007.15._icone1510_84.

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13

Kozinsky, Boris, and David J. Singh. "Thermoelectrics by Computational Design: Progress and Opportunities." Annual Review of Materials Research 51, no. 1 (July 26, 2021): 565–90. http://dx.doi.org/10.1146/annurev-matsci-100520-015716.

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The performance of thermoelectric materials is determined by their electrical and thermal transport properties that are very sensitive to small modifications of composition and microstructure. Discovery and design of next-generation materials are starting to be accelerated by computational guidance. We review progress and challenges in the development of accurate and efficient first-principles methods for computing transport coefficients and illustrate approaches for both rapid materials screening and focused optimization. Particularly important and challenging are computations of electron and phonon scattering rates that enter the Boltzmann transport equations, and this is where there are many opportunities for improving computational methods. We highlight the first successful examples of computation-driven discoveries of high-performance materials and discuss avenues for tightening the interaction between theoretical and experimental materials discovery and optimization.

14

Iranshahr, A., D. V. V. Voskov, and H. A. A. Tchelepi. "Tie-Simplex Parameterization for EOS-Based Thermal Compositional Simulation." SPE Journal 15, no. 02 (March 3, 2010): 545–56. http://dx.doi.org/10.2118/119166-pa.

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Summary Thermodynamic equilibrium computations are usually the most time-consuming component in compositional reservoir flow simulation. A compositional space adaptive tabulation (CSAT) approach was developed as a preconditioner for equation of state (EOS) computations in isothermal compositional simulation. The compositional space is decomposed into sub- and supercritical regions. In the subcritical region, we adaptively parameterize the compositional space using a small number of tie-lines, which are assembled into a table. The critical surface is parameterized and used to identify supercritical compositions. The phase-equilibrium information for a composition is interpolated as a function of pressure using the tie-line table. We extend the CSAT approach to thermal problems. Given an overall composition at a fixed temperature, the boundary between sub- and supercritical pressures is represented by the critical tie-line and the corresponding minimal critical pressure (MCP). A small set of subcritical tie-lines is computed and stored for a given temperature. This process is repeated for the pressure and temperature ranges of interest, and a coarse (regular) tie-line table is constructed. Close to the critical boundary, a refined tie-line table is used. A combination of regular and refined interpolation improves the robustness of the tie-line search procedure and the overall efficiency of the computations. Several challenging problems, including an unstructured heterogeneous discrete fracture field model with 26 components, are used to demonstrate the robustness and efficiency of this general tie-line-based parameterization method. Our results indicate that CSAT provides accurate treatment of the near-critical region. Moreover, the computational efficiency of the method is at least an order of magnitude better than that of standard EOS-based reservoir simulation approaches. We also show the efficiency gains relative to standard techniques as a function of the number of gridblocks in the simulation model.

15

Romani, Roger W., Mohan Rajagopal, Forrest J. Rogers, and Carlos A. Iglesias. "EUV/Soft X-ray Spectra for Low B Neutron Stars." International Astronomical Union Colloquium 152 (1996): 443–47. http://dx.doi.org/10.1017/s0252921100036368.

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Recent ROSAT and EUVE detections of spin-powered neutron stars suggest that many emit ‘thermal’ radiation, peaking in the EUV/soft X-ray band. These data constrain the neutron stars’ thermal history, but interpretation requires comparison with model atmosphere computations, since emergent spectra depend strongly on the surface composition and magnetic field. As recent opacity computations show substantial change to absorption cross sections at neutron star photospheric conditions, we report here on new model atmosphere computations employing such data. The results are compared with magnetic atmosphere models and applied to PSR J0437−4715, a low field neutron star.

16

Sieres, Jaime, Antonio Campo, and José Martínez-Súarez. "Natural convection air flow in vertical upright-angled triangular cavities under realistic thermal boundary conditions." Thermal Science 20, no. 5 (2016): 1407–20. http://dx.doi.org/10.2298/tsci130530018s.

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This paper presents an analytical and numerical computation of laminar natural convection in a collection of vertical upright-angled triangular cavities filled with air. The vertical wall is heated with a uniform heat flux; the inclined wall is cooled with a uniform temperature; while the upper horizontal wall is assumed thermally insulated. The defining aperture angle ? is located at the lower vertex between the vertical and inclined walls. The finite element method is implemented to perform the computational analysis of the conservation equations for three aperture angles ? (= 15?, 30? and 45?) and height-based modified Rayleigh numbers ranging from a low Ra = 0 (pure conduction) to a high 109. Numerical results are reported for the velocity and temperature fields as well as the Nusselt numbers at the heated vertical wall. The numerical computations are also focused on the determination of the value of the maximum or critical temperature along the hot vertical wall and its dependence with the modified Rayleigh number and the aperture angle.

17

Cotta, Renato M., Péricles C. Pontes, Adam H. R. Sousa, Carolina P. Naveira-Cotta, and Kleber M. Lisboa. "Computational-analytical simulation of microsystems in process intensification." High Temperatures-High Pressures 50, no. 6 (2021): 469–95. http://dx.doi.org/10.32908/hthp.v50.1189.

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Heat and mass transfer enhancement techniques, either passive or active, have an important role in the more general goal of process intensification in modern engineering developments. In this context, the study of transport phenomena at the nano- and micro-scales aims far beyond the plain miniaturization of devices, being mainly directed towards process efficiency improvement and lower energy and raw materials consumption. The analysis of heat and mass transfer at such scales has required the development or extension of both theoretical and experimental methodologies. In light of the inherent multiscale nature of microfluidic devices, classical fully numerical methodologies often require large refined meshes with associated costly computations. A hybrid numerical-analytical approach for the analysis of microfluidic and thermal micro-systems is here reviewed, which includes a computational-analytical integral transform method for partial differential direct problems, that, together with mixed symbolic-numerical computations, lead to robust cost-effective algorithms for micro-scale transport phenomena analysis. Examples of this hybrid approach in selected applications are then examined more closely, including micro-reactors for continuous biodiesel synthesis with multiple reactive interfaces and three-dimensional thermal micro-devices with solid-fluid thermal conjugation.

18

Blaszczyk, Andreas, Reto Flückiger, Thomas Müller, and Carl-Olof Olsson. "Convergence behaviour of coupled pressure and thermal networks." COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering 33, no. 4 (July 1, 2014): 1233–50. http://dx.doi.org/10.1108/compel-12-2012-0378.

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Purpose – The purpose of this paper is to present a method for thermal computations of power devices based on a coupling between thermal and pressure networks. The concept of the coupling as well as the solution procedure is explained. The included examples demonstrate that the new method can be efficiently used for design of transformers and other power devices. Design/methodology/approach – The bidirectional propagation of temperature signal is introduced to the pressure network, which enables control of the power flow and a close coupling to the thermal network. The solution method is based on automatic splitting of the network definition (netlist) into two separate networks and iteratively solving the model using the Newton-Raphson approach as well as the adaptive relaxation enhanced by the direction change control. Findings – The proposed approach offers reliable convergence behaviour even for models with unknown direction of the fluid flow (bidirectional flows). The accuracy is sufficient for engineering applications and comparable with the computational fluid dynamics method. The computation times in the range of milliseconds and seconds are attractive for using the method in engineering design tools. Originality/value – The new method can be considered as a foundation for a consistent network modelling system of arbitrary thermodynamic problems including fluid flow. Such a modelling system can be used directly by device designers since the complexity of thermodynamic formulations is encapsulated in predefined network elements while the numerical solution is based on a standard network description and solvers (Spice).

19

Amano, R. S., K. D. Wang, and V. Pavelic. "A Study of Rotor Cavities and Heat Transfer in a Cooling Process in a Gas Turbine." Journal of Turbomachinery 116, no. 2 (April 1, 1994): 333–38. http://dx.doi.org/10.1115/1.2928369.

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A high-temperature flow through a gas turbine produces a high rate of turbulent heat transfer between the fluid flow field and the turbine components. The heat transfer process through rotor disks causes thermal stress due to the thermal gradient just as the centrifugal force causes mechanical stresses; thus an accurate analysis for the evaluation of thermal behavior is needed. This paper presents a numerical study of thermal flow analysis in a two-stage turbine in order to understand better the detailed flow and heat transfer mechanisms through the cavity and the rotating rotor-disks. The numerical computations were performed to predict thermal fields throughout the rotating disks. The method used in this paper is the “segregation” method, which requires a much smaller number of grids than actually employed in the computations. The results are presented for temperature distributions through the disk and the velocity fields, which illustrate the interaction between the cooling air flow and gas flow created by the disk rotation. The temperature distribution in the disks shows a reasonable trend. The numerical method developed in this study shows that it can be easily adapted for similar computations for air cooling flow patterns through any rotating blade disks in a gas turbine.

20

König, Burkhard, Wolfgang Pitsch, Michael Klein, Rudolf Vasold, Matthias Prall, and Peter R. Schreiner. "Carbonyl- and Carboxyl-Substituted Enediynes: Synthesis, Computations, and Thermal Reactivity." Journal of Organic Chemistry 66, no. 5 (March 2001): 1742–46. http://dx.doi.org/10.1021/jo001417q.

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21

Marepalli, Prabhakar, Sanjay R. Mathur, and Jayathi Y. Murthy. "Automatic differentiation approach for property computations in nanoscale thermal transport." Computer Physics Communications 252 (July 2020): 107138. http://dx.doi.org/10.1016/j.cpc.2020.107138.

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22

Denizart, O., M. Vincent, and J. F. Agassant. "Thermal stresses and strains in injection moulding: experiments and computations." Journal of Materials Science 30, no. 2 (1995): 552–60. http://dx.doi.org/10.1007/bf00354424.

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23

Arslan, Erkan, and Dan G. Cacuci. "Predictive modeling of liquid-sodium thermal–hydraulics experiments and computations." Annals of Nuclear Energy 63 (January 2014): 355–70. http://dx.doi.org/10.1016/j.anucene.2013.07.029.

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24

Górecki, Paweł, and Krzysztof Górecki. "Measurements and Computations of Internal Temperatures of the IGBT and the Diode Situated in the Common Case." Electronics 10, no. 2 (January 18, 2021): 210. http://dx.doi.org/10.3390/electronics10020210.

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This article proposes effective methods of measurements and computations of internal temperature of the dies of the Insulted Gate Bipolar Transistor (IGBT) and the diode mounted in the common case. The nonlinear compact thermal model of the considered device is proposed. This model takes into account both self-heating phenomena in both dies and mutual thermal couplings between them. In the proposed model, the influence of the device internal temperature on self and transfer thermal resistances is taken into account. Methods of measurements of each self and transfer transient thermal impedances occurring in this model are described and factors influencing the measurement error of these methods are analysed. Some results illustrating thermal properties of the investigated devices including the IGBT and the antiparallel diode in the common case are shown and discussed. Computations illustrating the usefulness of the proposed compact thermal model are presented and compared to the results of measurements. It is proved that differences between internal temperature of both dies included in the TO-247 case can exceed even 15 K.

25

Lukes, J. R., D. Y. Li, X. G. Liang, and C. L. Tien. "Molecular Dynamics Study of Solid Thin-Film Thermal Conductivity." Journal of Heat Transfer 122, no. 3 (March 1, 2000): 536–43. http://dx.doi.org/10.1115/1.1288405.

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This study uses the molecular dynamics computational technique to investigate the thermal conductivity of solid thin films in the direction perpendicular to the film plane. In order to establish a benchmark reference, the computations are based on the widely used Lennard-Jones argon model due to its agreement with experimental liquid-phase data, its physically meaningful parameters, and its simple two-body form. Thermal conductivity increases with film thickness, as expected from thin-film experimental data and theoretical predictions. The calculated values are roughly 30 percent higher than anticipated. Varying the boundary conditions, heat flux, and lateral dimensions of the films causes no observable change in the thermal conductivity values. The present study also delineates the conditions necessary for meaningful thermal conductivity calculations and offers recommendations for efficient simulations. This work shows that molecular dynamics, applied under the correct conditions, is a viable tool for calculating the thermal conductivity of solid thin films. More generally, it demonstrates the potential of molecular dynamics for ascertaining microscale thermophysical properties in complex structures. [S0022-1481(00)02303-3]

26

Aziz, Asim, Wasim Jamshed, and Taha Aziz. "Mathematical model for thermal and entropy analysis of thermal solar collectors by using Maxwell nanofluids with slip conditions, thermal radiation and variable thermal conductivity." Open Physics 16, no. 1 (April 18, 2018): 123–36. http://dx.doi.org/10.1515/phys-2018-0020.

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Abstract In the present research a simplified mathematical model for the solar thermal collectors is considered in the form of non-uniform unsteady stretching surface. The non-Newtonian Maxwell nanofluid model is utilized for the working fluid along with slip and convective boundary conditions and comprehensive analysis of entropy generation in the system is also observed. The effect of thermal radiation and variable thermal conductivity are also included in the present model. The mathematical formulation is carried out through a boundary layer approach and the numerical computations are carried out for Cu-water and TiO2-water nanofluids. Results are presented for the velocity, temperature and entropy generation profiles, skin friction coefficient and Nusselt number. The discussion is concluded on the effect of various governing parameters on the motion, temperature variation, entropy generation, velocity gradient and the rate of heat transfer at the boundary.

27

Górecki, Krzysztof. "Influence of the Semiconductor Devices Cooling Conditions on Characteristics of Selected DC–DC Converters." Energies 14, no. 6 (March 17, 2021): 1672. http://dx.doi.org/10.3390/en14061672.

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The problem of an influence of cooling conditions of power semiconductor devices on properties of selected DC–DC converters is considered. The new version of electrothermal average model of a diode-transistor switch for SPICE (Simulation Program with Integrated Circuit Emphasis) is used in the investigations. This model makes it possible to take into account thermal inertia of semiconductor devices as well as mutual thermal interactions between these devices. The investigations are performed for boost and buck converters containing the power MOS (Metal-Oxide-Semiconductor) transistor and the diode. Computational results obtained using the proposed model are shown and discussed. Particularly, an influence of thermal phenomena in the diode and the power MOS transistor on the converters output voltage and internal temperature of the semiconductor devices is considered. The correctness of the selected results of computations was verified experimentally.

28

Chen, Xin, Yinghua Wu, and Victor S. Batista. "Matching-pursuit/split-operator-Fourier-transform computations of thermal correlation functions." Journal of Chemical Physics 122, no. 6 (February 8, 2005): 064102. http://dx.doi.org/10.1063/1.1848513.

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29

TAGAMI, Daisuke. "F3-1 Numerical computations of energy blance in thermal convection problems." Proceedings of The Computational Mechanics Conference 2007.20 (2007): 30–31. http://dx.doi.org/10.1299/jsmecmd.2007.20.30.

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30

Kumar, Rajesh, and Anupam Dewan. "URANS computations with buoyancy corrected turbulence models for turbulent thermal plume." International Journal of Heat and Mass Transfer 72 (May 2014): 680–89. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2014.01.066.

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31

Hong, Yang, Dan Han, Bo Hou, Xinyu Wang, and Jingchao Zhang. "High-Throughput Computations of Cross-Plane Thermal Conductivity in Multilayer Stanene." International Journal of Heat and Mass Transfer 171 (June 2021): 121073. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2021.121073.

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32

Woodruff, S. B. "Some computational challenges of developing efficient parallel algorithms for data-dependent computations in thermal-hydraulics supercomputer applications." Nuclear Engineering and Design 146, no. 1-3 (February 1994): 463–71. http://dx.doi.org/10.1016/0029-5493(94)90351-4.

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33

Agarwal, D. K., S. W. J. Welch, G. Biswas, and F. Durst. "Planar Simulation of Bubble Growth in Film Boiling in Near-Critical Water Using a Variant of the VOF Method." Journal of Heat Transfer 126, no. 3 (June 1, 2004): 329–38. http://dx.doi.org/10.1115/1.1737779.

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A planar simulation of film boiling and bubble formation in water at 373°C, 219 bar on an isothermal horizontal surface was performed by using a volume of fluid (VOF) based interface tracking method. The complete Navier-Stokes equations and thermal energy equations were solved in conjunction with a interface mass transfer model. The numerical method takes into account the effect of temperature on the transportive thermal properties (thermal conductivity and specific heat) of vapor, effects of surface tension, the interface mass transfer and the corresponding latent heat. The computations provided a good insight into film boiling yielding quantitative information on unsteady periodic bubble release patterns and on the spatially and temporally varying film thickness. The computations also predicted the transport coefficients on the horizontal surface, which were greatly influenced by the variations in fluid properties, compared to calculations with constant properties.

34

Górecki, Paweł. "Compact Thermal Modeling of Power Semiconductor Devices with the Influence of Atmospheric Pressure." Energies 15, no. 10 (May 12, 2022): 3565. http://dx.doi.org/10.3390/en15103565.

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The efficiency of the heat dissipation process generated in semiconductor devices depends on many factors, related both to the parameters of the cooling system and environmental factors. Regarding the latter factors, ambient temperature and volume in which the device operates are typically indicated as the most important. However, in the case of the operation of semiconductor devices in non-standard conditions, e.g., in stratospheric airships, the thermal parameters of the device are significantly affected by a low value of atmospheric pressure. This paper presents a compact thermal model of a semiconductor device, considering the effects of reduced atmospheric pressure along with its experimental verification under various cooling conditions, thus obtaining high compliance for computation and measurement results. The formulated model is dedicated to circuit-level simulations, and it enables computations of the junction temperature of the semiconductor device in a short time. It is also shown that lowering atmospheric pressure can double the value of the junction-ambient thermal resistance.

35

Bohn, D. E., and J. Lepers. "Numerical Simulation of Swirl-Stabilized Premixed Flames With a Turbulent Combustion Model Based on a Systematically Reduced Six-Step Reaction Mechanism." Journal of Engineering for Gas Turbines and Power 123, no. 4 (October 1, 2000): 832–38. http://dx.doi.org/10.1115/1.1377597.

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This paper presents the application of a detailed combustion model for turbulent premixed combustion to a swirl-stabilized premix burner. Computations are carried out for atmospheric pressure and elevated pressure of 9 atm. Results of computations for atmospheric pressure are compared to experimental data. The combustion model is of the joint-pdf type. The model is based on the characteristics of turbulent combustion under conditions typical for gas turbine burners. It incorporates a systematically reduced six-step reaction mechanism yielding direct computation of radical concentrations via transport equations or steady-state assumptions. The model is able to simulate combustion of fuel gases containing methane, carbon monoxide, hydrogen, carbon dioxide, and water. It is therefore applicable to both methane and low-BTU fuel gas combustion. Based on computed radical concentrations, a post-processor for NOx formation is applied. This post-processor considers thermal formation of nitrogen oxides and NO formation via the nitrous oxide path.

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Gouldstone, A., Y.-L. Shen, S. Suresh, and C. V. Thompson. "Evolution of stresses in passivated and unpassivated metal interconnects." Journal of Materials Research 13, no. 7 (July 1998): 1956–66. http://dx.doi.org/10.1557/jmr.1998.0275.

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This paper discusses computational simulations of the evolution of stresses and deformation in unpassivated and SiO2-passivated Al lines on Si substrates. The finite element model accounts for elastic-plastic deformation in the Al lines during etching, passivation, and subsequent thermal cycling, by recourse to a generalized plane strain formulation within the context of a unit cell with appropriately constrained boundary conditions. The effects of different controlled variations in thermal history, and in the width, height, spacing, and yield behavior of the Al lines are analyzed; all these factors are seen to have potentially strong effects on the evolution of stresses within the lines. The predictions of the computations presented in this work are amenable for direct comparisons with experiments of curvature evolution along and perpendicular to the lines upon patterning, passivation, and thermal loading. The predicted stresses in metal interconnects can be directly used for reliability modeling purposes.

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Patra, Paramita, S. A. Khan, M. Bala, D. K. Avasthi, and S. K. Srivastava. "Assessing a thermal spike model of swift heavy ion–matter interactions via Pd1−xNix/Si interface mixing." Physical Chemistry Chemical Physics 21, no. 30 (2019): 16634–46. http://dx.doi.org/10.1039/c9cp02052g.

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38

Blond, Eric, Tarek Merouki, Nicolas Schmitt, Emmanuel de Bilbao, and Alain Gasser. "Multiphysics Modelling Applied to Refractory Behaviour in Severe Environments." Advances in Science and Technology 92 (October 2014): 301–9. http://dx.doi.org/10.4028/www.scientific.net/ast.92.301.

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It is a common practice to design refractory linings with the help of thermal computations, thermochemistry analyses and strong workman know-how. Their mechanical design is often limited to simple thermo-elastic computations. Sometimes computations are refined considering non-linear mechanical behaviour, even if corrosion often induces additional chemical strain and strong change in service of the mechanical behaviour of the refractory. The aim of this presentation is to briefly recast the irreversible thermodynamic framework in order to underline the implications of some basic thermodynamic concepts in term of refractory behaviour modelling. Then, the use of these concepts to develop fully 3D finite element simulations accounting simultaneously for thermal, mechanical and chemistry phenomena will be illustrated on the particular case of SiC-based refractory. Comparison between long duration oxidation test at high temperature and model prediction allows the validation of the proposed approach. Then, an extension to the industrial case of refractory lining in Waste to Energy plant will be illustrated. The interest of taking into account the thermo-chemo-mechanical coupling effects is shown.

39

Quan, Enqian, Min Xu, Weigang Yao, and Xunliang Yan. "Revisit of the variable stiffness method for aeroelastic computations with/without thermal effects based on computational fluid dynamics." Journal of Fluids and Structures 105 (August 2021): 103330. http://dx.doi.org/10.1016/j.jfluidstructs.2021.103330.

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40

Hernandez-Nunez, Luis, Alicia Chen, Gonzalo Budelli, Matthew E. Berck, Vincent Richter, Anna Rist, Andreas S. Thum, et al. "Synchronous and opponent thermosensors use flexible cross-inhibition to orchestrate thermal homeostasis." Science Advances 7, no. 35 (August 2021): eabg6707. http://dx.doi.org/10.1126/sciadv.abg6707.

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Body temperature homeostasis is essential and reliant upon the integration of outputs from multiple classes of cooling- and warming-responsive cells. The computations that integrate these outputs are not understood. Here, we discover a set of warming cells (WCs) and show that the outputs of these WCs combine with previously described cooling cells (CCs) in a cross-inhibition computation to drive thermal homeostasis in larval Drosophila. WCs and CCs detect temperature changes using overlapping combinations of ionotropic receptors: Ir68a, Ir93a, and Ir25a for WCs and Ir21a, Ir93a, and Ir25a for CCs. WCs mediate avoidance to warming while cross-inhibiting avoidance to cooling, and CCs mediate avoidance to cooling while cross-inhibiting avoidance to warming. Ambient temperature–dependent regulation of the strength of WC- and CC-mediated cross-inhibition keeps larvae near their homeostatic set point. Using neurophysiology, quantitative behavioral analysis, and connectomics, we demonstrate how flexible integration between warming and cooling pathways can orchestrate homeostatic thermoregulation.

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Acharya, Ragini, Brian Evans, Jonathan Pitt, Francesco Costanzo, and Kenneth K. Kuo. "COUPLING OF TRANSIENT THERMAL AND MECHANICAL STRESSES COMPUTATIONS IN GRAPHITE NOZZLE MATERIALS." International Journal of Energetic Materials and Chemical Propulsion 16, no. 2 (2017): 175–95. http://dx.doi.org/10.1615/intjenergeticmaterialschemprop.2018024875.

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42

Vyazovkin, Sergey, Alan K. Burnham, José M. Criado, Luis A. Pérez-Maqueda, Crisan Popescu, and Nicolas Sbirrazzuoli. "ICTAC Kinetics Committee recommendations for performing kinetic computations on thermal analysis data." Thermochimica Acta 520, no. 1-2 (June 2011): 1–19. http://dx.doi.org/10.1016/j.tca.2011.03.034.

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43

Gasmelseed, Akram. "New head models extracted from thermal infrared (IR) images for dosimetry computations." Computer Methods in Biomechanics and Biomedical Engineering 14, no. 7 (July 2011): 665–71. http://dx.doi.org/10.1080/10255842.2011.563738.

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44

Auerbach, I., D. A. Benson, S. G. Beard, and G. F. Wright. "Evaluation of thermal and kinetic properties suitable for high heating rate computations." Journal of Thermophysics and Heat Transfer 3, no. 4 (October 1989): 395–400. http://dx.doi.org/10.2514/3.28766.

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45

Min, Daeho, Hyeongjun Kim, Hoon Lee, Chaesoo Lee, and Chongam Kim. "Accurate and efficient computations of phase-changing flows in thermal vapor compressors." Applied Thermal Engineering 128 (January 2018): 320–34. http://dx.doi.org/10.1016/j.applthermaleng.2017.08.149.

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46

Koenig, Burkhard, Wolfgang Pitsch, Michael Klein, Rudolf Vasold, Matthias Prall, and Peter R. Schreiner. "ChemInform Abstract: Carbonyl- and Carboxyl-Substituted Enediynes: Synthesis, Computations, and Thermal Reactivity." ChemInform 32, no. 28 (May 25, 2010): no. http://dx.doi.org/10.1002/chin.200128051.

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47

Kouhi, M., M. Ghoranneviss, B. Malekynia, H. Hora, G. H. Miley, A. H. Sari, N. Azizi, and S. S. Razavipour. "Resonance effect for strong increase of fusion gains at thermal compression for volume ignition of Hydrogen Boron-11." Laser and Particle Beams 29, no. 1 (March 2011): 125–34. http://dx.doi.org/10.1017/s026303461100005x.

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AbstractAn anomalously strong increase of nuclear fusion gains for laser driven compression and thermal ignition of hydrogen-boron11 has been discovered from computations by using the latest results of Newins and Swain about details of a resonance maximum of the astrophysical S-function at 148 keV for the reaction cross-sections. Extensive computations based on volume ignition showed some usual improvements of the fusion gains. However, for a very narrow range of parameters, the increase of the gain was found to be higher by more than a factor 6. This is very unusual in all similar computations and is related to retrograde properties which were known for other parameter values. On top it is most important that the anomalous range is in the practically very interesting range for incorporation of laser pulse energies of few megajoules. The gains of up to 20 may be of interest for power generation in future by the high density fusion scheme.

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Bakardjiev, Mario, Josef Holub, Zdeňka Růžičková, Aleš Růžička, Jindřich Fanfrlík, Bohumil Štíbr, Michael L. McKee, and Drahomír Hnyk. "Transformation of various multicenter bondings within bicapped-square antiprismatic motifs: Z-rearrangement." Dalton Transactions 50, no. 35 (2021): 12098–106. http://dx.doi.org/10.1039/d0dt04225k.

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Mutual rearrangements in the whole series of bicapped-square antiprismatic closo-C2B8H10 are reported. High-quality computations and experimentally observed thermal rearrangements disprove the earlier postulated dsd (diamond-square-diamond) scheme for these isomerizations.

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Zhang, Zhen, Dong-Bo Zhang, Tao Sun, and Renata M. Wentzcovitch. "The Phonon Quasiparticle Approach for Anharmonic Properties of Solids." Journal of Physics: Conference Series 2207, no. 1 (March 1, 2022): 012042. http://dx.doi.org/10.1088/1742-6596/2207/1/012042.

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Abstract Knowledge of lattice anharmonicity is essential to elucidate distinctive thermal properties in crystalline solids. Yet, accurate ab initio investigations of lattice anharmonicity encounter difficulties owing to the cumbersome computations. Here we introduce the phonon quasiparticle approach and review its application to various materials. This method efficiently and reliably addresses lattice anharmonicity by combining ab initio molecular dynamics and lattice dynamics calculations. Thus, in principle, it accounts for full anharmonic effects and overcomes finite-size effects typical of ab initio molecular dynamics. The validity and effectiveness of the current approach are demonstrated in the computation of thermodynamic and heat transport properties of weakly and strongly anharmonic systems.

50

Górecki, Paweł, Krzysztof Górecki, and Janusz Zarębski. "Accurate Circuit-Level Modelling of IGBTs with Thermal Phenomena Taken into Account." Energies 14, no. 9 (April 22, 2021): 2372. http://dx.doi.org/10.3390/en14092372.

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This paper proposes a new compact electrothermal model of the Insulated Gate Bipolar Transistors (IGBT) dedicated for SPICE (Simulation Program with Integrated Circuit Emphasis). This model makes it possible to compute the non-isothermal DC characteristics of the considered transistor and the waveforms of terminal voltages and currents of the investigated device and its internal temperature at transients. This model takes into account the nonlinearity of thermal phenomena in this device. The form of the formulated model is described and the problem of estimating its parameter values is discussed. The correctness of the proposed model was verified experimentally both at DC operation and at transients. The obtained results are compared to the results of computations performed with the use of the classical literature model. A very good agreement between the results of measurements and computations performed with the new model is obtained at different cooling conditions and in a wide range of changes of parameters characterising the electrical excitation of the tested device.

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