Heat generation in devices for magnetic-pulse processing of materials

The problem of analysis of non-stationary heat generation due to the flow of electric current in devices for magnetic-pulse processing of materials is considered. An analysis of the available information sources led to the conclusion that a large number of studies in this area are devoted to the study of heat transfer processes during technological operations of induction heating. In other technological operations of magnetic-pulse processing of materials, heat release is also significant. In this case, a non-stationary inhomogeneous temperature field can lead to significant temperature deformations. This, in turn, can cause a loss in the performance of the device due to destruction or irreversible deformation. Adequate modeling of non-stationary temperature propagation in this case is an obligatory step in carrying out computational analysis in the process of designing technological devices. A general strategy is proposed for determining the propagation of a non-stationary temperature field in the presence of a non-stationary non-uniform electromagnetic field. The proposed strategy presupposes a general solution of the problems of the propagation of the electromagnetic field and the temperature field within the framework of a unified design scheme. The use of the finite element method is proposed as a numerical method. The finite element method, when used in such problems, allows one to draw up iterative procedures that can be used to take into account the nonlinear effects associated with the influence of temperature on the electro-physical properties of materials. The problem of sequential determination of a non-stationary, non-uniform electromagnetic field and a non-stationary temperature field in composite matrices intended for electromagnetic pressing of powders of super-strong refractory materials is considered. The distribution of some quantitative characteristics of the electromagnetic field, as well as the dependence of temperature on time are presented.

Penetration of non-uniform electromagnetic field into conducting body

The study is based on the exact analytical solution for the general conjugation problem of three-dimensional quasi-stationary field at a flat interface between dielectric and conducting media. It is determined that non-uniform electromagnetic field always decreases in depth faster than uniform field. The theoretical conclusion is confirmed by comparing the results of analytical and numerical calculations. The concept of strong skin effect is extended to the case when penetration depth is small not only compare to the characteristic body size, but also when the ratio of the penetration depth to the distance from the surface of body to the sources of the external field is small parameter. For strong skin effect in its extended interpretation, the influence of external field non-uniformity to electromagnetic field formation both at the interface between dielectric and conducting media and to the law of decrease field in conducting half-space is analyzed. It is shown, at the interface the expressions for the electric and magnetic intensities in the form of asymptotic series in addition to local field values of external sources contain their derivatives with respect to the coordinate perpendicular to the interface. The found expressions made it possible to generalize the approximate Leontovich impedance boundary condition for diffusion of non-uniform field into conducting half-space. The difference between the penetration law for the non-uniform field and the uniform one takes place in the terms of the asymptotic series proportional to the small parameter to the second power and to the second derivative with respect to the vertical coordinate from the external magnetic field intensity at the interface.

On the dynamics of spinning particle in nonlinear relativity

In order to study the dynamics of spinning particles in R-Minkowski space–time, first we have used the Bhabha–Corben model to describe how a spinning particle behave in a uniform electromagnetic field. Then, to extend the Mathisson–Papapetrou equations to R-Minkowski space–time, that correspond to de Sitter space–time given by a conformally flat metric, it was necessary to determine the Killing vectors, which allowed us to find the equations of motion that describe the dynamics of spinning particles.

Near-field BER and EVM Measurement at 5.8 GHz in Mode-stirred Metal Enclosure

This work presents over-the-air (OTA) performance, near-field bit-error-ratio (BER), and error vector magnitude (EVM) measurement using software-defined radio (SDR) in the mode-stirred metal enclosure at 5.8 GHz. The metal enclosure is stirred at 5.8 GHz using metallic paddle rotating with uniform speed. Paddle rotation creates a uniform electromagnetic field in the metal enclosure. The electromagnetic field environment in the metal enclosure can be controlled by loading the cavity with absorbing material. Field absorption can be different depending on the amount of absorbing material and location of the absorbers in the metal enclosure. It is shown that signal attenuation increases as we increase the number of absorbers. BER and EVM are measured in this environment and the performance of SDR based digital receiver is analyzed in this environment at RF frequency of 5.8 GHz.

Emission spectrum and trajectory of a charged particle in the field of an inhomogeneous electromagnetic wave

Using the example of a non-uniform electromagnetic wave created by superposition of two plane monochromatic electromagnetic waves that are arbitrarily directed relative to each other, an approach is demonstrated that allows one to simulate a wide spectrum of electromagnetic waves. The complete system of equations describing the motion of an electron in a non-uniform electromagnetic field is solved numerically. The features of the trajectory and emission spectrum of the electron were found and investigated.

Electromagnetic Field Simulation in a Microwave Chamber with Multiple Waveguides

While microwaves have many features and advantages, problems may occur, including non-heating, partial overheating, and fire due to damaged magnetrons caused by reflected waves, when they are used without a proper understanding of the permittivity of the object to be heated, the electromagnetic field distribution, the matching between the chamber and the waveguide, and the reflected electromagnetic waves. Simulation was performed using the Ansys HFSS tool. Conditions for the uniform electromagnetic field were derived using the distance from the waveguides to the ceramic material as well as the microwave energy intensity as major parameters.

Magnetic Wave Technology of Grinding Slime Separation

It is proved that abrasive-holding conglomerates are effectively destroyed when slime is separated in the non-uniform electromagnetic field, which results in steel chips and abrasive separation. Magnetic wave separation technology mechanism for bearing production grinding slime is described in the article. The techniques for optimal regimes of magnetic field gradient determination and alternating magnetic field induction intervals regulation for the effective separation of magnetic and non-magnetic fractions are proposed. Practical application options for the slime separation products are shown.

Real-Time Estimation of Some Thermodynamics Properties During a Microwave Heating Process

<p class="MsoNormal"><span lang="EN-US">This work considers the prediction in real time of physicochemical parameters of a sample heated in a uniform electromagnetic field. The thermal conductivity (K)</span><!--[if gte msEquation 12]><m:oMath><i style='mso-bidi-font-style:normal'><span lang=EN-US style='font-family:"Cambria Math","serif"'><m:r>(</m:r><m:r>K</m:r><m:r>) </m:r></span></i></m:oMath><![endif]--><!--[if !msEquation]--><!--[endif]--><span lang="EN-US">and the </span><span lang="EN">combination of density and heat capacity terms (pc)</span><span lang="EN"> were estimated as a demonstrative example.</span><span lang="EN-US">The sample (with known geometry) was subjected to electromagnetic radiation, generating a uniform and time constant volumetric heat flow within it. Real temperature profile was simulated adding white Gaussian noise to the original data, obtained from the theoretical model. For solving the objective function, simulated annealing and genetic algorithms, along with the traditional Levenberg-Marquardt method were used for comparative purposes. Results show similar findings of all algorithms for three simulation scenarios, as long as the signal to noise ratio sits at least at 30 dB. It means for practical purposes, that the estimation procedure presented here requires both, a good experimental design and an electronic instrumentation correctly specified.</span><span lang="EN-US">If both requirements are satisfied simultaneously, it is possible to estimate these type of parameters on-line, without need for an additional experimental setup.</span></p><p class="MsoNormal"><span lang="EN-US">This work considers the prediction in real time of physicochemical parameters of a sample heated in a uniform electromagnetic field. The thermal conductivity </span><!--[if gte msEquation 12]><m:oMath><i style='mso-bidi-font-style:normal'><span lang=EN-US style='font-family:"Cambria Math","serif"'><m:r>(</m:r><m:r>K</m:r><m:r>) </m:r></span></i></m:oMath><![endif]--><!--[if !msEquation]--><!--[endif]--><span lang="EN-US">and the </span><span lang="EN">combination of density and heat capacity terms (</span><!--[if gte msEquation 12]><m:oMath><i style='mso-bidi-font-style:normal'><span lang=EN style='font-family:"Cambria Math","serif"; mso-ansi-language:EN'><m:r>ρc</m:r><m:r>)</m:r></span></i></m:oMath><![endif]--><!--[if !msEquation]--><!--[endif]--><span lang="EN"> were estimated as a demonstrative example.</span><span lang="EN-US">The sample (with known geometry) was subjected to electromagnetic radiation, generating a uniform and time constant volumetric heat flow within it. Real temperature profile was simulated adding white Gaussian noise to the original data, obtained from the theoretical model. For solving the objective function, simulated annealing and genetic algorithms, along with the traditional Levenberg-Marquardt method were used for comparative purposes. Results show similar findings of all algorithms for three simulation scenarios, as long as the signal to noise ratio sits at least at 30 dB. It means for practical purposes, that the estimation procedure presented here requires both, a good experimental design and an electronic instrumentation correctly specified.</span><span lang="EN-US">If both requirements are satisfied simultaneously, it is possible to estimate these type of parameters on-line, without need for an additional experimental setup.</span></p>