Influence Of Thermal Field Research Articles

A data-driven force-thermal coupling load identification method considering multi-source uncertainties of structural characteristics and measuring noises

The problem of load identification denotes identifying loads based on the measurement of structural responses, which is the inverse problem in structural dynamics. With advancements in aeronautical technology, the working environment of aircraft becomes even more complex. To accurately monitor and forecast the load environment where the structure works can provide guidance for the structural design of aircraft and predict potential structural damage. However, with the development of hypersonic aircraft, the influence of thermal field also cannot be ignored besides external forces that are applied to the structure, thus, there is an urgent need for effective methods to identify both force and thermal loads. In this paper, firstly, A data-driven load identification method and various load identification strategies for the identification of force-thermal load based on Artificial Neural Networks are proposed, and in different loading cases the relative error of identification is less than 5 %, with the training process converging efficiently within a short time; additionally, multi-source uncertainties, including Gaussian white noises and structural uncertainties, are simulated, and their influence on load identification is also evaluated; moreover, sensor placement optimization based on particle swarm optimization is carried out to enhance accuracy of load identification, and the number of sensors and the corresponding optimal placement of sensors are determined, it can be proved via numerical examples that the optimized sensor placement can reduce the error of load identification by more than 90 % of that of a random sensor placement.

Thermal analysis of radiative and electromagnetic flowing of hybridity nanofluid via Darcy–Forchheimer porous material with slippage constraints

The goal of this research is to address the electrical magnetohydrodynamic flow of hybridity nanoparticles through a stretched surface with the impact of the Darcy–Forchheimer permeable medium. By identifying appropriate similarity factors, the partial differential equation is converted into a set of ordinary differential equation with the help of R-K fourth-order approach based on shooting technique. The velocity, thermal, friction factor coefficient, and heat transport are investigated comprehensively for the influence of numerous blossoming parameters refer to in the present study by plots graphically. It is accomplished that due to the influence of the electric field associated with first- and second-order velocity slip impacts, the motion of liquid slows down. Moreover, the stream velocity grows for the boosting scales of mixed convection, which leads to eliminating sticking impact. The variation of important flowing variables on heat transport and the drag coefficient is also investigated. Here augmenting valuation of mixed convection parameter corresponds to boost up velocity curve. Furthermore, the influence of thermal field and heat transport are similar in view of the Biot number.

Electromagnetic-thermal two-way coupling analysis and application on helium-cooled solid blanket

The blanket plays an important role in fusion reactor and stands extremely high thermal and electromagnetic loads during operation situation and plasma disruption event, brings the need for precise thermal and electromagnetic analysis. Since the thermal field and EM field interact with each other nonlinearly, we develop a method of electromagnetic-thermal two-way coupling by using finite element software COMSOL. The coupling analyses of blanket under steady state and MD event are implemented and the results are analyzed. For steady state, the influences of coupling effects are relatively small but still recommended to be considered for a high precision analysis. The influence of thermal field on EM field can't be ignored under MD events. The variation of force density could cause a significant change in stress in certain parts of blanket. The influence of Joule heat during MD event is negligible, yet the potential temperature rise caused by induced current after MD event still needs to be researched.

Thermal Estimation and Thermal Design for Coupling Coils of 6.6 kW Wireless Electric Vehicle Charging System

Wireless electric vehicle charging technology is developing in the direction of high power levels. However, more generated heat brought by higher power will accelerate the system’s aging and can even lead to damage. An excellent thermal design for the magnetic coupler can reduce each part’s maximum temperature, ensuring long-term operation reliability. Therefore, in this article, the magnetic coupler’s thermal estimation and design are studied based on a 6.6 kW wireless electric vehicle charging system. First, the calculation method of internal resistance of a litz coil, core loss, and eddy current loss of a shielding aluminum plate are studied. Considering the influence of thermal fields on material properties, each part’s power loss calculation formula is further modified to improve the accuracy. After that, heat dissipation research is carried out. The heat dissipation measures, such as filling the surface of the shielding aluminum plate with thermal conductive silicone grease, are proposed. Finally, the effectiveness of the heat dissipation measures is verified by simulation and experiments. The experiment shows that the error between the power loss value of each part calculated by simulation and measured by the experiment is less than 15%, and the maximum temperature of the magnetic coupler is controlled below 80 °C.

Changes in the nickel hydroxide properties under the influence of thermal field in situ and ex situ during electrochemical synthesis

Nickel hydroxide is widely used in supercapacitors, alkaline batteries, for the electrocatalytic oxidation of organic contaminants, etc. Due to their electrochemical activity, Ni(OH)2 (α+β) samples of a layer structure synthesized in a slit diaphragm electrolyzer are the most promising. The effect of the thermal field on the structural characteristics of layered (α+β) Ni(OH)2 was studied. The effect was assessed in two ways: 1) internal (in situ) cooling directly in the electrolyzer by cooling the cathode from the rear side; 2) external (ex situ) heating directly after the electrolyzer when passing through a spiral heat exchanger heated to 90 °C. The crystal structure of the samples was studied by X-ray phase analysis. It was shown that the base sample obtained without changing the thermal field was a monophase layered (α+β) structure with a high content of α-modification and a gradient transition from α to β through a number of intermediate structures. The crystallinity of the sample was not high. During the internal cooling of the cathode, the crystallinity decreased and the fraction of the α-modification increased. External heating of the nickel hydroxide suspension immediately after leaving the electrolyzer led to the recrystallization of the samples with the decomposition of the (α+β) layered structure and formation of β-Ni(OH)2 with high crystallinity. It was found that external 6-minute heating did not change the crystal structure. This is explained by the fact that the aging process of nickel hydroxide at an elevated temperature is a crystal-chemical transformation, which is characterized by an induction period, during which the rate of the process is minimal.As a result, the study has shown the possibility of controlling the type of forming crystalline modification of nickel hydroxide and its crystallinity by changing the internal (in situ) or external (ex situ) thermal field

Investigation on Al6Fe Fibers of Al-3 Wt Pct Fe Alloy at Different Mold Temperatures

Al-3Fe alloys with nearly full Al6Fe fibers are obtained via iron mold casting at different mold temperatures (293 K, 323 K, 373 K, and 423 K). The shapes of the Al6Fe fibers and their spatial distribution in the alloys are characterized by scanning electron microscopy and transmission electron microscopy. Thermal curves are recorded to help analyze the solidification behavior. The influence of thermal field on the solidification behavior of Al-Al6Fe eutectic is analyzed by comparing the detailed portraits of Al6Fe fibers via the deep etching method. The microstructures in the central area of the ingots are more complex and variable with the change of mold temperature. The morphologies of Al6Fe fibers under different conditions are presented and exhibit strong regional characteristics. The solidified manner of Al6Fe phases in the central region is believed to be affected by a local negative temperature gradient caused by the homogenous nucleation of equiaxed eutectic colonies. The selection of types of secondary phases in the undercooling melt in central areas is found to be closely related to the latent heat releasing rate.

A micro–macro scale approach for thermal effects in ferroelectrics

The influence of thermal fields on the electromechanical behavior of ferroelectric ceramics under cyclic electric loading is presented. To predict the temperature effect, a 3D micromechanical model for tetragonal domain switching is extended by including thermal effects. Numerical simulations were done through the finite element program Abaqus with the help of a user-defined element. Besides external heat sources, a change in temperature is considered by internal heat generated due to domain switching. Material properties are assumed to be linearly dependent on the temperature. The temperature influence on the behavior of ferroelectrics is shown by means of the strain and polarization hysteresis loops. The model shows a good qualitative agreement with the experimental results available in the literature.

INTEGRATED PHOTOGENERATION OF BIOLOGICAL TISSUES AT DAMAGES OF ITS STATE

Introduction. Studies on the regeneration of living tissue tissues with chromotherapy show good results compared to standard treatment methods.Main part. The article is offered the creation of new therapeutic radiation regimes that are intended to regenerate damaged biological tissues. Studied new modes of physiotherapy integrated radiation molded considering possible changes in the time correction mode and under biological structures, which made influence. Thus, the mode shape of physiotherapeutic wave are integrated optical radiation that affects the living organism due to the frequency of the main carrier signal and frequency modulation, which correspond to the spectral range of variations selected body systems. The use of combinations of pulse mode is possible for some systems of the body, as each structure of a living organism has a frequency range of spectral characteristics. So, the author’s device PROMIN-ARIA was applied. The influence of thermal fields on the depth of radiation penetration in a phantom of biological multilayer specimen, which is formed as a result of irradiation by an integrated physiotherapeutic wave, is investigated. Conclusion. The results of the work make a new study of the temperature changes of the design sample of the phantom of biological tissue using specific radiation modes and can be used in other studies and practice of treatment of injuries.In the future, it is important to use different types of pulse modulation to create the necessary initial radiation parameters, because such a method of treatment is flexible and allows the physician to choose the effect that will be made on the affected tissue or organs in one or another case, based on the localization of the lesion, the type of illness, the method of irradiation of the site, the area of influence.

Plane contact problem of interaction between a rigid heat-conducting wedge and an elastic layer under nonstationary friction heat release

We consider a solution to the new plane problem of contact interaction with an elastic layer of a rigid, heat-conducting cross-sectional die in the form of a bounded or unbounded wedge. Using the apparatus of integral transformations, we have obtained an exact solution of the heat-conduction equations for the die and the layer, which permits reducing the problem stated to a system of integral equations whose structure is determined by the kind of thermophysical conditions on the interaction surface. This enables us to make the mathematical statement of the problem more realistic in terms of the distribution of thermoelastic stresses and adequately estimate the influence of thermal fields on the value of the contact pressure and the character of its distribution.