Статті в журналах: "Thermal field model"

1

Dmitriev, A. N., and Yu V. Pakharukov. "Thermoelectric model of the Earth's magnetic field." Oil and Gas Studies, no. 2 (June 11, 2021): 39–52. http://dx.doi.org/10.31660/0445-0108-2021-2-39-52.

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A variant of the thermoelectric model of the Earth's dipole magnetic field is considered. It is based on geothermoelectric currents present in the planet's core. The currents cyclically change their direction, which leads over time either to warming on the Earth, if their movement is directed towards the Earth's crust, or to cooling, when moving towards the inner core. With each change in the direction of movement of the thermal currents, the poles of the Earth's magnetic field are inverted simultaneously. The inversion process is instantaneous (on the scale of planetary time) and is not the result of a gradual reversal on the 180° Earth's magnetic axis. At the moment of inversions of thermal currents in the core, the total geomagnetic field decreases to the level of 4.6∙10-6 T, which is constantly supported by thermal currents of semi-conducting rocks of the lower mantle. The considered version of the thermoelectric model of the Earth's magnetic field may be promising for studying the magnetic fields of planets in the Solar system.

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2

Liu, Hong, Jin Guo Li, and Yong Tian Wang. "Fast Computing Model for Thermal Field of Auto Lamp." Key Engineering Materials 364-366 (December 2007): 783–88. http://dx.doi.org/10.4028/www.scientific.net/kem.364-366.783.

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Thermal field analysis for automotive lamps is a complicated thermodynamics problem. According to the features of structure and lighting process of automotive lamps, a simple and convenient model is put forward here for analyzing their thermal field. Under certain assumptions, it simplifies the complicated geometrical structure to the relative simple cavities and only considers the influence of thermal conduction and thermal radiation as main forms of heat transfer for thermal field of the lamps. The consistency of numerical analysis and actual test demonstrates that this modeling method calculates thermal field of the lamps quickly and perfectly, and indicates its practical signification.

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3

Rajendran, S., C. C. Chao, D. P. Hill, J. P. Kalejs, and Vern Overbye. "Magnetic and thermal field model of EFG system." Journal of Crystal Growth 109, no. 1-4 (February 1991): 82–87. http://dx.doi.org/10.1016/0022-0248(91)90160-7.

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4

Drahoš, Peter, Vladimír Kutiš, and Róbert Lenický. "Thermocouple Sensor Influence on Temperature Field in SMA Actuator." Applied Mechanics and Materials 394 (September 2013): 50–56. http://dx.doi.org/10.4028/www.scientific.net/amm.394.50.

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The paper deals with thermal analysis, modeling and simulation of the Shape Memory Alloy (SMA) actuator with temperature sensor. Because the capabilities of analytical description of SMA system are limited, numerical simulations of model have to be performed. Two different numerical models are investigated - lumped and continuous model. Simple parametric lumped model of actuator thermal field is developed in order to describe thermal field at the measuring point. The characteristic parameters of the lumped model are set up according to continuous coupled electric-thermal model made in ANSYS FEM program.

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5

Wang, Jingxia, Yusheng Hu, Ming Cheng, Biao Li, and Bin Chen. "Bidirectional Coupling Model of Electromagnetic Field and Thermal Field Applied to the Thermal Analysis of the FSPM Machine." Energies 13, no. 12 (June 14, 2020): 3079. http://dx.doi.org/10.3390/en13123079.

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The paper aimed to find an accurate and fast model to study the electromagnetic (EM) thermal (TH) filed coupling calculation for the TH analysis in the flux switching permanent magnet (FSPM) machine. It is extremely important to know the coupling mechanism between the EM field and TH field for the designers and users of the FSPM machines. Firstly, in order to study the EM properties of the silicon steel sheet with the temperature, the Epstein frame experiment was set up, where the effect of dc magnetic bias on the core loss is also considered. In order to save the computation time, the bidirectional coupling model based on 2D finite element (FE) EM field and 3D asymmetric minimum element TH field is established, and the steady state and transient TH fields are calculated, respectively. For the transient bidirectional coupling of EM field and TH field, a method based on the adaptive adjustment calculation step is adopted to improve the computing speed. The temperature rise experiment of the prototype was carried out to verify the accuracy of the proposed coupling model. The experimental results are in good agreement with the simulation results.

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6

Suh, S. W. "A Hybrid Near-Field/Far-Field Thermal Discharge Model for Coastal Areas." Marine Pollution Bulletin 43, no. 7-12 (July 2001): 225–33. http://dx.doi.org/10.1016/s0025-326x(01)00074-1.

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7

Karma, Alain, and Wouter-Jan Rappel. "Phase-field model of dendritic sidebranching with thermal noise." Physical Review E 60, no. 4 (October 1, 1999): 3614–25. http://dx.doi.org/10.1103/physreve.60.3614.

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8

Zubert, Mariusz, Tomasz Raszkowski, Agnieszka Samson, Marcin Janicki, and Andrzej Napieralski. "The distributed thermal model of fin field effect transistor." Microelectronics Reliability 67 (December 2016): 9–14. http://dx.doi.org/10.1016/j.microrel.2016.09.021.

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9

Sinelnikov, D., D. Bulgadaryan, V. Kurnaev, and M. Lobov. "The model of thermal field emission from tungsten fuzz." Journal of Physics: Conference Series 941 (December 2017): 012024. http://dx.doi.org/10.1088/1742-6596/941/1/012024.

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10

Jensen, Kevin L., Patrick G. O’Shea, and Donald W. Feldman. "Generalized electron emission model for field, thermal, and photoemission." Applied Physics Letters 81, no. 20 (November 11, 2002): 3867–69. http://dx.doi.org/10.1063/1.1521491.

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11

SHTEFURA, JULIA, KOSTIANTYN SHEVCHENKO, OLEH KOZYR, and OLEKSII STATSENKO. "MODELLING OF TEMPERATURE FIELD DISTRIBUTION IN BIOLOGICAL TISSUE THERMAL LESION." HERALD OF KHMELNYTSKYI NATIONAL UNIVERSITY 297, no. 3 (July 2, 2021): 208–15. http://dx.doi.org/10.31891/2307-5732-2021-297-3-208-215.

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Early determination of the thermal lesion degree in case of scald accelerates the treatment process and increases its effectiveness. The thermal lesion degree can be evaluated by determining the temperature difference between healthy and injured areas of biological tissue. For this purpose, a model of biological tissue in the form of a multilayer structure can be used. Heat exchange processes in such a structure are described by a generalized thermal model. Such structure contains conditionally flat heat sources located in each layer, which have the form of a developed network of blood vessels. The considered model of biological tissue quite accurately describes the heat exchange processes in body tissues. The article considers heat exchange processes that take place in biological tissue and a number of assumptions that should be used to mathematically describe these processes were identified. During the analysis of heat transfer process, the equations of temperature distribution in the tissue layers and the boundary conditions that describe the thermal interaction of the model with the environment are determined. As a result, the model of the stationary thermal regime of a biological tissue fragment in the form of a generalized thermal model and a mathematical model of the temperature field distribution in this fragment is obtained. This model is determined by many parameters, which are divided into 3 groups: thermophysical parameters; structural and topological parameters; parameters of the blood vascular system. Models of the particular fragment thermal regime are unequivocally determined by a combination of these parameters. For the analysis of temperature in any point of biological tissue modelled part mathematical model of temperature field distribution in stationary mode was developed. This model allows reasonable approach to the thermal lesion degree evaluation on the basis of the surface temperature difference between healthy and injured areas of tissue.

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12

MARTIN, JAMES E. "FIELD-INDUCED RHEOLOGY IN UNIAXIAL AND BIAXIAL FIELDS." International Journal of Modern Physics B 15, no. 06n07 (March 20, 2001): 574–95. http://dx.doi.org/10.1142/s0217979201005039.

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Steady and oscillatory shear 3-D simulations of electro- and magnetorheology in uniaxial and biaxial fields are presented, and compared to the predictions of the chain model. These large scale simulations are three dimensional, and include the effect of Brownian motion. In the absence of thermal fluctuations, the expected shear thinning viscosity is observed in steady shear, and a striped phase is seen to rapidly form in a uniaxial field, with a shear slip zone in each sheet. However, as the influence of Brownian motion increases, the fluid stress decreases, especially at lower Mason numbers, and the striped phase eventually disappears, even when the fluid stress is still high. In a biaxial field, an opposite trend is seen, where Brownian motion decreases the stress most significantly at higher Mason numbers. To account for the uniaxial steady shear data we propose a microscopic chain model of the role played by thermal fluctuations on the rheology of ER and MR fluids that delineates the regimes where an applied field can impact the fluid viscosity, and gives an analytical prediction for the thermal effect. In oscillatory shear, a striped phase again appears in a uniaxial field, at strain amplitudes greater than ~0.15, and the presence of a shear slip zone creates strong stress nonlinearities at low strain amplitudes. In a biaxial field, a shear slip zone is not created, and so the stress nonlinearities develop only at expected strain amplitudes. The nonlinear dynamics of these systems is shown to be in good agreeement with the Kinetic Chain Model.

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13

Lin, Ze Jin, Jie Hong Yuan, Yuan Li, Xi Jie Yan, Shi Ming Zhou, and Run Jing Chen. "A Temperature Field Model of Complicated Thermal Analysis System Based on Thermal Network Method." Advanced Materials Research 694-697 (May 2013): 695–98. http://dx.doi.org/10.4028/www.scientific.net/amr.694-697.695.

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Based on the thermal network method and heat transfer theory, a temperature field simulation model of complicated thermal analysis system was established by Matlab Simulink. Based on the model, a steady-state temperature field of a helicopter tail reducer was calculated in the normal lubrication. The model is more accurate and reliable than the traditional algorithm. Meanwhile, the model can calculate the time-varying process of the temperature field, corresponding to the transient temperature field.

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14

Alfat, Sayahdin, Masato Kimura, and Alifian Mahardhika Maulana. "Phase Field Models for Thermal Fracturing and Their Variational Structures." Materials 15, no. 7 (March 31, 2022): 2571. http://dx.doi.org/10.3390/ma15072571.

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It is often observed that thermal stress enhances crack propagation in materials, and, conversely, crack propagation can contribute to temperature shifts in materials. In this study, we first consider the thermoelasticity model proposed by M. A. Biot and study its energy dissipation property. The Biot thermoelasticity model takes into account the following effects. Thermal expansion and contraction are caused by temperature changes, and, conversely, temperatures decrease in expanding areas but increase in contracting areas. In addition, we examine its thermomechanical properties through several numerical examples and observe that the stress near a singular point is enhanced by the thermoelastic effect. In the second part, we propose two crack propagation models under thermal stress by coupling a phase field model for crack propagation and the Biot thermoelasticity model and show their variational structures. In our numerical experiments, we investigate how thermal coupling affects the crack speed and shape. In particular, we observe that the lowest temperature appears near the crack tip, and the crack propagation is accelerated by the enhanced thermal stress.

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15

Bagrov, A. R., and E. K. Bashkirov. "DYNAMICS OF THE THREE-QUBITS TAVIS — CUMMINGS MODEL." Vestnik of Samara University. Natural Science Series 28, no. 1-2 (December 29, 2022): 95–105. http://dx.doi.org/10.18287/2541-7525-2022-28-1-2-95-105.

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In this article, we have studied the entanglement dynamics of three identical qubits (natural or artificial two-level atoms) resonantly interacting with the one mode of the thermal field of a microwave lossless resonator via one-photon transitions. An exact solution of the quantum time Schrodinger equation is found for the total wave function of the system for the initial separable and entangled states of qubits and the Fock initial state of the resonator. On the basis of this solution, an exact solution of the quantum Liouville equation for the total time-dependent density matrix of the system in the case of a thermal field of the resonator is constructed. The exact solution for the full density matrix is used to calculate the criterion of entanglement of pairs of qubits negativity. The resultsof numerical simulation of the time dependence of the negativity of pairs of qubits showed that with an increase in the intensity of the thermal resonator field, the degree of entanglement of pairs of qubits decreases. It is also shown that In the model under consideration, for any initial states of qubits and intensities of the thermal field of the resonator, the effect of sudden death of entanglement takes place. This behavior of the entanglement parameter in the model under consideration differs from that in the two-qubit model. For two-qubit model, the effect of the sudden death of entanglement takes place only for the initial entangled states of qubits and intense thermal fields of the resonator.

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16

Stokowiec, K., D. Kotrys-Działak, and P. Jastrzębska. "Verification of the Fanger model with field experimental data." Journal of Physics: Conference Series 2339, no. 1 (September 1, 2022): 012027. http://dx.doi.org/10.1088/1742-6596/2339/1/012027.

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Abstract Thermal comfort is one of the main aspect of human life due to the period of time each of us spends inside of the enclosed room on one hand as well as the health issues connected with the sick building syndrome on the other. Presently, the international standards are based on the Fanger model with calculations of proper indexes according to the inside air parameters as well as characteristics for room users. The paper presents the verification of Fanger model with experimental data obtained from research conducted in 6 classrooms of an intelligent, educational building. The measurements were acquired by means of Testo 400 meter where air parameters such as temperature or humidity were collected. For other evidence the questionnaire was prepared, where respondents presented their thermal sensation together with the information of their clothes present thermal insulation. The results proved that the Fanger model is not precise, since the findings calculated with the international standard differ from those obtained from the questionnaires.

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17

Lan, Tianbao, Yihuan Wei, Yanyan Fu, and Yuezhu Zhang. "The field descriptions for thermal-equilibrium Friedmann–Robertson–Walker universe." Modern Physics Letters A 29, no. 20 (June 17, 2014): 1450085. http://dx.doi.org/10.1142/s0217732314500850.

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In this paper, we show the simple expression for the energy density of the thermal-equilibrium Friedmann–Robertson–Walker (TEFRW) universe and study the problem how to describe it by using some field models. We analyze the properties of the quintessence field in the quintessence model, calculate the tachyon potential in the tachyon model and point out that the latter model cannot give the whole description for the TEFRW universe. It is found that the two-field model can be responsible for describing the whole evolution process of the TEFRW universe.

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18

Koyama, Shinnosuke, та Joji Nasu. "Field-angle dependence of thermal transport in Kitaev-Γ model". Journal of Physics: Conference Series 2164, № 1 (1 березня 2022): 012071. http://dx.doi.org/10.1088/1742-6596/2164/1/012071.

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Abstract We investigate the magnetic field effect on the Kitaev model with the Γ-type interaction, which plays an essential role in understanding the magnetic properties of real materials. We examine the mean-field phase diagram and thermal Hall conductivity using the linear spin-wave theory. We find that the Γ interaction substantially changes the field-angle dependence of the thermal Hall conductivity and suppresses its magnitude. The suppression is caused by the enhancement of the low-energy magnon gap while increasing the Γ interaction.

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19

Pantaleo, M., and T. R. Walter. "The ring-shaped thermal field of Stefanos crater, Nisyros Island: a conceptual model." Solid Earth Discussions 5, no. 2 (November 14, 2013): 2005–42. http://dx.doi.org/10.5194/sed-5-2005-2013.

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Abstract. Fumarole fields related to hydrothermal processes release the heat of the underground through permeable pathways. Thermal changes, therefore, are likely to depend also on the variation of these pathways. As these paths may affect or even control the temperature field at the surface, their understanding is relevant to applied and basic science alike. A common difficulty, however, in surface temperature field studies at active volcanoes is that the parameters controlling the ascending routes of fluids are poorly constrained in general. Here we analyze the crater of Stefanos, Nisyros (Greece), and highlight complexities in the spatial pattern of the fumarole field related to permeability conditions. There may be different explanations for the observed permeability changes, such as structural control, lithology, weathering, and heterogeneous sediment accumulation and erosion. We combine high resolution infrared mosaics and grain-size analysis of soils, aiming to elaborate parameters controlling the appearance of the fumarole field. We find a ring-shaped thermal field located within the explosion crater, which is dependent on contrasts of the soil granulometry and volcanotectonic history. We develop a conceptual model of how the ring-shaped thermal field has formed at the Stefanos crater and similarly at other volcanic edifices, highlighting the importance of local permeability contrast that may increase or decrease the thermal fluid flux.

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20

Jensen, Kevin L., Joseph M. Connelly, John J. Petillo, John R. Harris, Serguei Ovtchinnikov, Aaron J. Jensen, John Burke, et al. "Semi-analytic model of a carbon fiber thermal-field emitter." Journal of Applied Physics 129, no. 9 (March 7, 2021): 095107. http://dx.doi.org/10.1063/5.0044800.

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21

Ferrer, E. J., V. P. Gusynin, and V. de la Incera. "Thermal conductivity in 3D NJL model under external magnetic field." European Physical Journal B - Condensed Matter and Complex Systems 33, no. 4 (June 2003): 397–411. http://dx.doi.org/10.1140/epjb/e2003-00181-8.

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22

Albrecht, J. D., P. P. Ruden, S. C. Binari, and M. G. Ancona. "AlGaN/GaN heterostructure field-effect transistor model including thermal effects." IEEE Transactions on Electron Devices 47, no. 11 (2000): 2031–36. http://dx.doi.org/10.1109/16.877163.

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23

Hou, Zhen-Bing, and R. Komanduri. "Magnetic Field Assisted Finishing of Ceramics—Part I: Thermal Model." Journal of Tribology 120, no. 4 (October 1, 1998): 645–51. http://dx.doi.org/10.1115/1.2833761.

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A thermal model for magnetic field assisted polishing of ceramic balls/rollers is presented. The heat source at the area of contact between the balls and the abrasives where material removal takes place is approximated to a disk. The disk heat source is considered as a combination of a series of concentric circular ring heat sources with different radii. Each ring in turn is considered as a combination of a series of infinitely small arc segments and each arc segment as a point heat source. Jaeger’s classical moving heat source theory (Jaeger, 1942; Carslaw and Jaeger, 1959) is used in the development of the model, starting from an instantaneous point heat source, to obtain the general solution (transient and steady-state) of the moving circular ring heat source problem and finally the moving disc heat source problem. Due to the formation of fine scratches during polishing (on the order of a few micrometers long), the conditions are found to be largely transient in nature. Calculation of the minimum flash temperatures and minimum flash times during polishing enables the determination if adequate temperatures can be generated for chemo-mechanical polishing or not. This model is applied in Part II for magnetic float polishing (MFP) of ceramic balls and in Part III for magnetic abrasive finishing (MAF) of ceramic rollers.

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24

Ginkin, V. P., S. M. Ganina, V. I. Strelov, I. Zh Bezbakh, and B. G. Zakharov. "Mathematical model of biocrystal growth under a thermal control field." Journal of Surface Investigation. X-ray, Synchrotron and Neutron Techniques 3, no. 1 (February 2009): 90–97. http://dx.doi.org/10.1134/s1027451009010169.

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25

Alonso, J. Diaz, J. M. Ibaez, and H. Sivak. "Field theoretical model for nuclear and neutron matter: Thermal effects." Physical Review C 39, no. 2 (February 1, 1989): 671–79. http://dx.doi.org/10.1103/physrevc.39.671.

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26

Pantaleo, M., and T. R. Walter. "The ring-shaped thermal field of Stefanos crater, Nisyros Island: a conceptual model." Solid Earth 5, no. 1 (April 1, 2014): 183–98. http://dx.doi.org/10.5194/se-5-183-2014.

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Abstract. Fumarole fields related to hydrothermal processes release the heat of the underground through permeable pathways. Thermal changes, therefore, are likely to depend also on the size and permeability variation of these pathways. There may be different explanations for the observed permeability changes, such as fault control, lithology, weathering/alteration, heterogeneous sediment accumulation/erosion and physical changes of the fluids (e.g., temperature and viscosity). A common difficulty, however, in surface temperature field studies at active volcanoes is that the parameters controlling the ascending routes of fluids are poorly constrained in general. Here we analyze the crater of Stefanos, Nisyros (Greece), and highlight complexities in the spatial pattern of the fumarole field related to permeability conditions. We combine high-resolution infrared mosaics and grain-size analysis of soils, aiming to elaborate parameters controlling the appearance of the fumarole field. We find a ring-shaped thermal field located within the explosion crater, which we interpret to reflect near-surface contrasts of the soil granulometry and volcanotectonic history at depth. We develop a conceptual model of how the ring-shaped thermal field formed at the Stefanos crater and similarly at other volcanic edifices, highlighting the importance of local permeability contrast that may increase or decrease the thermal fluid flux.

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27

Qu, Pu, Qiang Li, and Shu Fang Yang. "Temperature Field and Thermal Stress Analysis of Large Caliber Gun Barrel." Applied Mechanics and Materials 518 (February 2014): 150–54. http://dx.doi.org/10.4028/www.scientific.net/amm.518.150.

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In order to analyze the temperature fields, temperature grads, thermal stress and thermal strain of large caliber machine gun barrel during firing, an analysis model was established for large caliber machine gun. The finite element analyze model are founded and the boundary condition of the model are loaded. The results indicated the temperature, temperature grads, thermal stress and thermal strain of the large caliber gun tube during continuous shots. The effect of thermal pulse loading on thermal stress, thermal strain is very obviously. So, thermal pulse loading is the primary origin of thermal stress, thermal strain of the large caliber machine gun barrel. At the same time, the thermal pulse loading is one of the important factors affecting the life of the gun tube.

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28

Zhao, H., J. A. Souza, and J. C. Ordonez. "THERMAL MODEL FOR ELECTROMAGNETIC LAUNCHERS." Revista de Engenharia Térmica 7, no. 2 (December 31, 2008): 60. http://dx.doi.org/10.5380/reterm.v7i2.61779.

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This paper presents a 3D model for the determination of the temperature field in an electromagnetic launcher. The large amounts of energy that are dissipated into the structure of an electromagnetic launcher during short periods of time lead to a complicated thermal management situation. Effective thermal management strategies are necessary in order to maintain temperatures under acceptable limits. This paper constitutes an attempt to determine the temperature response of the launcher. A complete three-dimensional model has been developed. It combines rigid body movement, electromagnetic effects and heat diffusion together. The launcher consists of two parallel rectangular rails and an armature moving between them. Preliminary results show the current distribution on the rail cross-section, the localized resistive heating, and the rail transient temperature response. The simulation results are compared to prior work presented for a 2D geometry by Powell and Zielinski (2008).

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29

Luo, Yan Yan, Yi Wen, Liang Hao, Xin Wei Liu, Yi Jun Wang, Lei Liu, Fang Yao, Zhen Wang, and Shu Mei Zheng. "Numerical Analysis on Temperature Field of Electric Connectors." Advanced Materials Research 852 (January 2014): 602–7. http://dx.doi.org/10.4028/www.scientific.net/amr.852.602.

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The steady-state thermal analysis models are established based on the thermal analysis of the Electric connectors. With the consideration to the internal heat conduction and the convection cooling, the three-dimensional solid model is imposed by the reasonable loads and boundary conditions and analyzed by ANSYS thermal analysis module. The numerical analysis is made on the temperature field of a certain type of Electric connectors at different environmental temperature and different working current. The simulation results are compared with the monitoring test data.

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30

Xiang, Sitong, Xiaolong Zhu, and Jianguo Yang. "Modeling for spindle thermal error in machine tools based on mechanism analysis and thermal basic characteristics tests." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 228, no. 18 (April 11, 2014): 3381–94. http://dx.doi.org/10.1177/0954406214531219.

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This paper proposes a method to accurately predict thermal errors in spindles by applying experimental modifications to preliminary theoretical models. First, preliminary theoretical models of the temperature field and the thermal deformation are built via mechanism analysis, which is based on the size of the spindle and the parameters of the bearing. Then, thermal basic characteristics tests are conducted at two different initial temperatures. Finally, the results of the thermal basic characteristic tests are evaluated, and the preliminary theoretical model is modified to obtain the final model. A simulation of axial thermal deformation under different speeds is conducted by finite element analysis. It shows that the relationship between the axial thermal deformation and the speed is approximately linear. The model is validated via some experiments on the spindle of a numerical control lathe. The results indicate that the proposed model precisely predicts the spindle’s temperature field and multi-degree of freedom thermal errors.

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31

Wajnert, Dawid, and Bronisław Tomczuk. "Analysis of spatial thermal field in a magnetic bearing." Open Physics 16, no. 1 (March 20, 2018): 52–56. http://dx.doi.org/10.1515/phys-2018-0010.

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AbstractThis paper presents two mathematical models for temperature field analysis in a new hybrid magnetic bearing. Temperature distributions have been calculated using a three dimensional simulation and a two dimensional one. A physical model for temperature testing in the magnetic bearing has been developed. Some results obtained from computer simulations were compared with measurements.

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32

Alicki, Robert. "Limited thermalization for the Markov mean-field model of N atoms in thermal field." Physica A: Statistical Mechanics and its Applications 150, no. 2 (June 1988): 455–61. http://dx.doi.org/10.1016/0378-4371(88)90163-x.

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33

Wan, Wan, and Pinlei Chen. "A Fully Coupled Thermomechanical Phase Field Method for Modeling Cracks with Frictional Contact." Mathematics 10, no. 23 (November 23, 2022): 4416. http://dx.doi.org/10.3390/math10234416.

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Анотація:

In this paper, a thermomechanical coupled phase field method is developed to model cracks with frictional contact. Compared to discrete methods, the phase field method can represent arbitrary crack geometry without an explicit representation of the crack surface. The two distinguishable features of the proposed phase field method are: (1) for the mechanical phase, no specific algorithm is needed for imposing contact constraints on the fracture surfaces; (2) for the thermal phase, formulations are proposed for incorporating the phase field damage parameter so that different thermal conductance conditions are accommodated. While the stress is updated explicitly in the regularized interface regions under different contact conditions, the thermal conductivity is determined under different conductance conditions. In particular, we consider a pressure-dependent thermal conductance model (PDM) that is fully coupled with the mechanical phase, along with the other three thermal conductance models, i.e., the fully conductive model (FCM), the adiabatic model (ACM), and the uncoupled model (UCM). The potential of this formulation is showcased by several benchmark problems. We gain insights into the role of the temperature field affecting the mechanical field. Several 2D boundary value problems are addressed, demonstrating the model’s ability to capture cracking phenomena with the effect of the thermal field. We compare our results with the discrete methods as well as other phase field methods, and a very good agreement is achieved.

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34

Guo, Z., Jia Wei Mi, and Patrick S. Grant. "Phase Field Modelling of Dendrite Fragmentation during Thermal Shock." Materials Science Forum 654-656 (June 2010): 1524–27. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.1524.

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The dendrite grain growth of a succinonitrile based transparent alloy, their fragmentation under an intense thermal shock and the subsequnet morphology evolution during solidification have been simulated using a two-dimensional binary alloy phase field model coupled with heat and solute transfer. The effect of a sudden, rapid change in the thermal environment (thermal shock) was implemented in the model and the resulting effect on the incipient dendritic grain morphology was studied. Thermal shock effectively promoted the fragmentation of the dendritic grains, providing a significant grain multiplication effect to refine the final solidification microstructure.

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35

Al-Qadi, Imad L., Marwa M. Hassan, and Mostafa A. Elseifi. "Field and Theoretical Evaluation of Thermal Fatigue Cracking in Flexible Pavements." Transportation Research Record: Journal of the Transportation Research Board 1919, no. 1 (January 2005): 87–95. http://dx.doi.org/10.1177/0361198105191900110.

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Thermal cracking in flexible pavement occurs when the tensile stress exceeds the tensile strength of hot-mix asphalt at a given temperature or when fluctuating stresses and strains caused by temperature variation lead to a buildup of irrecoverable deformations over time. The objective of this study was twofold: ( a) to quantify the measured strain magnitude associated with thermal fatigue through field measurements and ( b) to present a three-dimensional, finite element (FE) model that accurately simulated thermal fatigue in flexible pavement. Results of the experimental program indicated that pavement response to thermal loading was associated with a high strain range, reaching a maximum recorded value of 350 μm/m. This finding confirms the hypothesis that the criticality of thermal fatigue arises from the high stress–strain level exhibited in each cycle rather than its frequency, which is usually the critical factor in load-associated fatigue cracking. Moreover, the developed FE model accurately simulated pavement response to thermal loading by conducting a sequential coupled heat transfer analysis. Results of the developed FE model were in agreement with field measurements and demonstrated the model's capability to simulate both the temperature and stress fields associated with thermal loading. This model may be used to evaluate pavement performance against transverse cracking induced by thermal fatigue.

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36

Pan, Lin, Xuelei Cheng, and Jinhong Xia. "Similarity Criterion of Freezing Model Test considering Nonlinear Variation of Thermal Parameters with Temperature." Mathematical Problems in Engineering 2020 (October 7, 2020): 1–11. http://dx.doi.org/10.1155/2020/7468034.

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The significant differences in specific heat and thermal conductivity of ice and water lead to the changes of specific heat and thermal conductivity of soil during the freezing process. This makes it hard for the temperature field similarity criterion based on constant thermal parameters to accurately reflect the temperature field evolution of soil mass caused by nonlinearity of thermal parameters in the process. Based on heat conduction differential equation considering nonlinear changes of thermal parameters, this paper uses similarity transformation method to derive the similarity criterion of the temperature field in the frozen soil model test and arrives at the conclusion that the prototype soil and model soil should meet when the original soil is used for the model test. At the same time, given the impact of the third boundary condition on the similarity criterion, the thermal physical similarity conditions for the model soil are derived. On this basis, ABAQUS finite element software is used to numerically simulate the linear and nonlinear prototype and model temperature fields. The third boundary condition considered the temperature evolution of the characteristic points during the freezing process is analyzed. The calculation results indicate that the nonlinear thermal conductivity similarity criterion established herein can correctly reflect the evolution process of the prototype frozen soil temperature field. It is also suggested that the model soil thermal parameters are reasonably calculated. At the same time, it shows that the nonlinear freezing similarity criterion of the soil, when the third boundary condition is satisfied, has clear physical meaning and higher practical value. The research results provide a practical and reasonable parameter calculation method for the model soil preparation in the frozen soil model test and a theoretical basis and technical support for the design and implementation of the water-heat-force coupling model test on frozen soil.

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37

ZHOU, ZHONGQIANG, ZHITONG WANG, and MINGJIANG YANG. "THERMAL MODEL FOR LASER-INDUCED DISCHARGE SURFACE STRENGTHENING." Surface Review and Letters 18, no. 06 (December 2011): 289–96. http://dx.doi.org/10.1142/s0218625x11014771.

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Анотація:

The temperature field due to laser-induced discharge surface strengthening (LIDSS) has significant influence on the microstructure transformation and also the formation quality of discharge pit. A transient axisymmetric thermal model is developed to estimate the temperature distribution during LIDSS based on Fourier heat conduction equation. In the model, a Gaussian heat input distribution is assumed; temperature-dependent material properties are applied and the latent heat of fusion and vaporization is calculated on an enthalpy method. As an application, we use this model to compute the temperature field during the process of tungsten tool electrode machining 1045 steel workpiece and find that the computational results are well consistent with the experimental data.

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38

Kunze, Kerstin E. "CMB anisotropies and linear matter power spectrum in models with non-thermal neutrinos and primordial magnetic fields." Journal of Cosmology and Astroparticle Physics 2021, no. 11 (November 1, 2021): 044. http://dx.doi.org/10.1088/1475-7516/2021/11/044.

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Abstract Angular power spectra of temperature anisotropies and polarization of the cosmic microwave background (CMB) as well as the linear matter power spectra are calculated for models with three light neutrinos with non-thermal phase-space distributions in the presence of a primordial stochastic magnetic field. The non-thermal phase-space distribution function is assumed to be the sum of a Fermi-Dirac and a gaussian distribution. It is found that the known effective description of the non-thermal model in terms of a twin thermal model with extra relativistic degrees of freedom can also be extended to models including a stochastic magnetic field. Numerical solutions are obtained for a range of magnetic field parameters.

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39

Kumar, Shailesh, Santosh Kumar Prasad, and Jyotirmay Banerjee. "Analysis of flow and thermal field in nanofluid using a single phase thermal dispersion model." Applied Mathematical Modelling 34, no. 3 (March 2010): 573–92. http://dx.doi.org/10.1016/j.apm.2009.06.026.

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40

Anikiev, Denis, Adrian Lechel, Maria Laura Gomez Dacal, Judith Bott, Mauro Cacace, and Magdalena Scheck-Wenderoth. "A three-dimensional lithospheric-scale thermal model of Germany." Advances in Geosciences 49 (December 20, 2019): 225–34. http://dx.doi.org/10.5194/adgeo-49-225-2019.

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Abstract. We present a 3-D lithospheric-scale model covering the area of Germany that images the regional characteristics of the structural configuration and of the thermal field. The structural model resolves major sedimentary, crustal and lithospheric mantle units integrated from previous studies of the Central European Basin System, the Upper Rhine Graben and the Molasse Basin, together with published geological and geophysical data. A combined workflow consisting of 3-D structural, gravity and thermal modelling is applied to derive the 3-D thermal configuration. The modelled temperature distribution is highly variable in response to an imposed heterogeneous distribution of thermal properties assigned to the different units. First order variations in the temperature field are mainly attributed to the thermal blanketing effect from the sedimentary cover, the variability in the amount of radiogenic heat produced within the different crystalline crust compartments and the implemented topology of the thermal Lithosphere-Asthenosphere Boundary.

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41

Saeed, Abdulkafi M., Kh Lotfy, and Alaa A. El-Bary. "Effect of Variable Thermal Conductivity and Magnetic Field for the Generated Photo-Thermal Waves on Microelongated Semiconductor." Mathematics 10, no. 22 (November 15, 2022): 4270. http://dx.doi.org/10.3390/math10224270.

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Анотація:

A theoretical analysis of the dynamic impacts of a novel model in the microelongated-stimulated semiconductor medium is investigated. The influence of the magnetic field of the optically excited medium is taken into consideration according to the photothermal transport processes. The governing equations were created during the electronic (ED) and thermoelastic (TED) deformation processes. Thermal conductivity of the semiconductor microelongation medium is taken as temperature dependent. The interaction of thermal, microelongate, plasma, and mechanical waves is examined. Dimensionless formulae are used to solve the main equations in two dimensions (2D) using the harmonic wave method. The physical field equations have complete solutions when some conditions are applied to the semiconductor surface. The theoretical microelongated semiconductor model employed in this experiment was confirmed by comparing it to certain earlier studies. The numerical simulation for the principal physical field distributions is graphically displayed when silicon (Si) material is employed. The topic of the discussion was the impact of several factors, such as the magnetic field, thermal memory, and microelongation, on the propagation of waves for major fields.

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42

SATO, H. T., and H. TOCHIMURA. "ON THERMAL PHASE STRUCTURE OF DEFORMED GROSS–NEVEU MODEL." Modern Physics Letters A 11, no. 39n40 (December 28, 1996): 3091–102. http://dx.doi.org/10.1142/s0217732396003076.

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We illustrate the phase structure of a deformed two-dimensional Gross–Neveu model which is defined by undeformed field contents plus deformed Pauli matrices. This deformation is based on two motives to find a more general polymer model and to estimate how q-deformed field theory affects on its effective potential. Some regions where chiral symmetry breaking and restoration take place repeatedly as temperature increasing are found.

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43

Saeed, Abdulkafi M., Kh Lotfy, and Alaa A. El-Bary. "Hall Current Effect of Magnetic-Optical-Elastic-Thermal-Diffusive Semiconductor Model during Electrons-Holes Excitation Processes." Journal of Mathematics 2022 (November 15, 2022): 1–17. http://dx.doi.org/10.1155/2022/6597924.

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Анотація:

In this study, a novel model is introduced when the Hall effect associated with a strong magnetic field is taken into account when the electrons and holes interact in the processes of semiconductor material. The plasma-elastic-thermal waves are investigated in the context of diffusive processes during optical-generated transport processes. The variable of thermal conductivity is obtained during graduated temperature due to the thermal impact of fallen light. The governing equations of the novel model are investigated in a unidimensional (1D) way when the electronics and elastic deformations have occurred. The Laplace transforms are used to convert the main dimensionless physical fields according to the initial conditions into the Laplace domain. When certain thermal, mechanical, holes, and electronic conditions are used, the analytical solutions of the fundamental fields can be produced to the outer surface of the semiconductor medium. Mathematically, the Laplacian computational inversion algorithm with a numerical approximation is used to achieve the fundamental physical quantities numerically in the time domain. The influences of several parameters (thermal relaxation times, Hall impact, and thermal conductivity parameters) on thermal conditions, mechanical stress, holes charge carrier field, and carrier density are prescribed with the help of graphical diagrams that are discussed theoretically.

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44

Atchley, A. L., S. L. Painter, D. R. Harp, E. T. Coon, C. J. Wilson, A. K. Liljedahl, and V. E. Romanovsky. "Using field observations to inform thermal hydrology models of permafrost dynamics with ATS (v0.83)." Geoscientific Model Development 8, no. 9 (September 1, 2015): 2701–22. http://dx.doi.org/10.5194/gmd-8-2701-2015.

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Abstract. Climate change is profoundly transforming the carbon-rich Arctic tundra landscape, potentially moving it from a carbon sink to a carbon source by increasing the thickness of soil that thaws on a seasonal basis. However, the modeling capability and precise parameterizations of the physical characteristics needed to estimate projected active layer thickness (ALT) are limited in Earth system models (ESMs). In particular, discrepancies in spatial scale between field measurements and Earth system models challenge validation and parameterization of hydrothermal models. A recently developed surface–subsurface model for permafrost thermal hydrology, the Advanced Terrestrial Simulator (ATS), is used in combination with field measurements to achieve the goals of constructing a process-rich model based on plausible parameters and to identify fine-scale controls of ALT in ice-wedge polygon tundra in Barrow, Alaska. An iterative model refinement procedure that cycles between borehole temperature and snow cover measurements and simulations functions to evaluate and parameterize different model processes necessary to simulate freeze–thaw processes and ALT formation. After model refinement and calibration, reasonable matches between simulated and measured soil temperatures are obtained, with the largest errors occurring during early summer above ice wedges (e.g., troughs). The results suggest that properly constructed and calibrated one-dimensional thermal hydrology models have the potential to provide reasonable representation of the subsurface thermal response and can be used to infer model input parameters and process representations. The models for soil thermal conductivity and snow distribution were found to be the most sensitive process representations. However, information on lateral flow and snowpack evolution might be needed to constrain model representations of surface hydrology and snow depth.

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45

Atchley, A. L., S. L. Painter, D. R. Harp, E. T. Coon, C. J. Wilson, A. K. Liljedahl, and V. E. Romanovsky. "Using field observations to inform thermal hydrology models of permafrost dynamics with ATS (v0.83)." Geoscientific Model Development Discussions 8, no. 4 (April 14, 2015): 3235–92. http://dx.doi.org/10.5194/gmdd-8-3235-2015.

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Анотація:

Abstract. Climate change is profoundly transforming the carbon-rich Arctic tundra landscape, potentially moving it from a carbon sink to a carbon source by increasing the thickness of soil that thaws on a seasonal basis. However, the modeling capability and precise parameterizations of the physical characteristics needed to estimate projected active layer thickness (ALT) are limited in Earth System Models (ESMs). In particular, discrepancies in spatial scale between field measurements and Earth System Models challenge validation and parameterization of hydrothermal models. A recently developed surface/subsurface model for permafrost thermal hydrology, the Advanced Terrestrial Simulator (ATS), is used in combination with field measurements to calibrate and identify fine scale controls of ALT in ice wedge polygon tundra in Barrow, Alaska. An iterative model refinement procedure that cycles between borehole temperature and snow cover measurements and simulations functions to evaluate and parameterize different model processes necessary to simulate freeze/thaw processes and ALT formation. After model refinement and calibration, reasonable matches between simulated and measured soil temperatures are obtained, with the largest errors occurring during early summer above ice wedges (e.g. troughs). The results suggest that properly constructed and calibrated one-dimensional thermal hydrology models have the potential to provide reasonable representation of the subsurface thermal response and can be used to infer model input parameters and process representations. The models for soil thermal conductivity and snow distribution were found to be the most sensitive process representations. However, information on lateral flow and snowpack evolution might be needed to constrain model representations of surface hydrology and snow depth.

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46

Zhao, Yu Hong, Wei Ming Yang, and Hua Hou. "A New Kind of FDM/FEM Squeeze Casting Temperature Field Calculation Model." Advanced Materials Research 641-642 (January 2013): 303–8. http://dx.doi.org/10.4028/www.scientific.net/amr.641-642.303.

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Анотація:

A new FDM/ FEM model is developed to simulate the temperature field during the solidification process of squeeze casting. So we can transform the FDM mesh into FEM mesh directly ,then established the relationship of pressure change and melting temperature change and correct the size of melting temperature value and other thermal physical parameters (such as the thermal conductivity)which is related to the temperature ,and establish the temperature and thermal physical parameter relationship to get a data base. The solidification process of AM50A magnesium alloy is simulated. Squeeze casting experiments are also incited for validating the new FDM/FEM model. It is shown that the results of numerical simulation are in agreement with the experimental results.

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47

HENNING, P. A., K. NAKAMURA, and Y. YAMANAKA. "THERMAL FIELD THEORY IN NON-EQUILIBRIUM STATES." International Journal of Modern Physics B 10, no. 13n14 (June 30, 1996): 1599–614. http://dx.doi.org/10.1142/s0217979296000696.

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Conventional transport theory is not really applicable to nonequilibrium systems which exhibit strong quantum effects. We present two different approaches to overcome this problem. Firstly we point out how transport equations may be derived that incorporate a nontrivial spectral function as a typical quantum effect, and test this approach in a toy model of a strongly interacting degenerate plasma. Secondly we explore a path to include nonequilibrium effects into quantum field theory through momentum mixing transformations in Fock space. Although the two approaches are completely orthogonal, they lead to the same coherent conclusion.

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48

Liu, Xie Quan, Jian Zheng, Zhan Jun Yao, and Bao Feng Li. "Residual Stress Field of Ellipsoidal Ceramic Particles Ni-Base Alloy Composite Coating." Key Engineering Materials 336-338 (April 2007): 1527–30. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.1527.

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Анотація:

Ni base alloy ceramic composite coating fabricated through vacuum fusion sintering process can acquire high strength and good thermal fatigue resistance. Composite coating was mainly composed of Ni base alloy and ellipsoidal ceramic particles with random orientation. The three-phases model is used to study the thermal expansion strains in composite coating. First, Eshebly-Mori-Tanaka method was used to determine effective eigen strain of two-phases model formed by the ellipsoidal matrix shell being around a ellipsoidal ceramic particle, then disturbance strain in two-phases model aroused thermal inconsistency is obtained. Finally thinking average stress in effective matrix vanish, the residual stress field in Ni base alloy and particles can be gotten by considering random orientation of two-phases models. It will exert influence on strength and fatigue life of the composite coating.

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49

Alonso, M., and Á. Comas. "Thermal model of a twin-tube cavitating shock absorber." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 222, no. 11 (November 1, 2008): 1955–64. http://dx.doi.org/10.1243/09544070jauto829.

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Анотація:

An analytical method to quantify the damping force of a generic twin-tube shock absorber for an automobile is proposed. Previous models by the present authors have accounted for fluid compressibility, chamber deformation, and fluid cavitation. This paper extends the work to thermal effects which have now been included. The variation in the force due to thermal effects caused by the energy dissipated within the damper is determined and the shock absorber temperature field is calculated. The results from the model are compared with those from simpler models (which do not include thermal effects) and are validated against the results from a real shock absorber. In terms of damping force, a good correlation is obtained, while acceptable results are obtained for the temperature field calculation.

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50

Kimura, Yasuo, Tomohisa Oba, Naoko Shimakura, and Michio Niwano. "The thermal-field emission model for carrier injection characteristics of an organic field effect transistor." Applied Physics Letters 94, no. 7 (February 16, 2009): 073303. http://dx.doi.org/10.1063/1.3086273.

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