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This paper proposes a way to represent the anisotropic nonlinear superconducting properties using a discrete model for magnetization with the corresponding critical parameters, equivalent to the Power Law model for currents. This simplified model makes it possible to analyze magnetic systems with superconducting elements in a stationary mode, which reduces the calculation time. Using of proposed model is demonstrated by the calculation of force interactions between high-temperature superconducting (HTS) samples and permanent magnet in zero-field-cooling (ZFC) and field-cooling (FC) modes. HTS bulks in the form of a prism and stack made of HTS tape are considered. The calculation of the electromagnetic field was carried out using the method of integral equations for field sources. The data of calculations are compared with the results of experimental studies. [ABSTRACT FROM AUTHOR]

Accurate and simple magnetic material behavior law is necessary to correctly model complete electromagnetic systems. In this paper, a new formulation based on the scalar quasi-static hysteresis Preisach model extended to dynamic behavior using fractional derivation dynamic contribution is proposed. The fractional contribution is solved using convolution which highly reduces the numerical issues. The order of the fractional derivation provides a new degree of freedom and allows to correctly obtain simulation results on a very large frequency bandwidth. By using such formulation, space discretization techniques (finite differences, finite elements) are avoided which are highly space and time consuming while keeping the global simulation results precise. The numerical implementation of the problem and some experimental validations are shown in this paper. [ABSTRACT FROM AUTHOR]

The article focuses on proposal and analysis of the physical models suitable to stress simulation and limit state prediction of components made of composite structure on Onyx basis. The observed parameters are physical properties of matrix and reinforcement. The additive manufacturing technologies also allow the production of complex shape constructions with cavities. The cavities are regions characteristic of damage initiations, but a realization of experimental measurements on inner surfaces of them to predict failure is problematic. Therefore, the exploitation of appropriate physical models and subsequently mathematical models is a method for observing of material behaviour using selected physical quantities beyond surface layers. The modelling of composite structures is viable using physical models, which working principle is based on homogenization of structure, for instance, representative volume elements (RVE). The primary disadvantage of RVE models is a complicated analysis of physical properties at inhomogeneity places of reinforcement. The physical model proposed in this paper describes each fibre separately regarding authentic physical properties and precise determination of fibre deposition in the matrix. Implementation of FEM programs with a primary objective to perform formation and analysis of the physical models, provides solution of various multiphysical problems, such as nonlinear behaviour of material induced by contact, temperature variation or interaction with other environments (temperature, fluid, electromagnetic fields), and so on. The main aspect of the presented concept is the generation of computational models with a precise definition of fibre deposition in the composite structure. The numerical analysis of loading and limit state prediction was executed on models of the composite structure. The structure includes onyx as a thermoplastic matrix and carbon fibres. The fundamental physical criterions for damage initiation assessment were stress state and strain at critical locations of matrix and reinforcement. [ABSTRACT FROM AUTHOR]

The paper deals with a mathematical model aimed to study electromagnetic and hydrodynamic processes in the inductor-ingot system during continuous DC mold casting. Experimental studies implied measurements of the vertical components of the liquid phase of meridional flows using the ultrasonic Doppler velocity probe. Results of mathematical and physical simulations were compared; dependences were obtained proving the validity of the proposed mathematical model. [ABSTRACT FROM AUTHOR]

The present paper considers a mathematical model of the process of volumetric induction heating of cylindrical pieces in a cylindrical inductor. The model is based on a machine for volumetric induction heating of R–ITO–630/1–A–L type with a SMK UB 2F2 power source. The inductor equivalent parameters have been calculated. To verify the results obtained from the model, a 2D model has been built in Comsol Multiphysics. [ABSTRACT FROM AUTHOR]

This paper describes iterative methods for the high frequency electromagnetic analysis using the finite element method of Maxwell equations including displacement current. The conjugate orthogonal conjugate gradient method has been widely used to solve a complex symmetric system. However, the conventional method suffers from oscillating convergence histories in large-scale analysis. In this paper, to solve large-scale complex symmetric systems arising from the formulation of the E method, an iterative substructuring method like the minimal residual method is presented, and the performance of the convergence of the method is evaluated by numerical results. As the result, the proposed method shows a stable convergence behavior and a fast convergence rate compared to other iterative methods. [ABSTRACT FROM AUTHOR]

The nonconformal domain decomposition methods (DDMs) of the hybrid finite element-boundary integral-multilevel fast multipole algorithm (FE-BI-MLFMA) are presented for computing large electromagnetic scattering/radiation problems. The numerical performance of different transmission conditions between finite element method (FEM) subdomains, and FEM and BI domains is studied in this paper. The Dirichlet transmission condition (DTC) employed at the interface between FEM and BI domains has faster convergence than the Robin-type transmission condition, and this finding is different from the conclusions for the FEM DDMs published in the literature. Furthermore, the cement-element (CE)-based dual-primal finite element tearing and interconnecting (FETI-DP) DDM has faster convergence than the Lagrange-multiplier-based FETI-DP method under the FE-BI system, and is also different from that under the system of the FEM with the absorbing boundary condition (FEM-ABC). It shows that the DDMs of FE-BI-MLFMA have some essential differences from those of FEM-ABC. The analysis of these numerical phenomena is presented in this paper. Further comparison between the DDMs of FE-BI-MLFMA and FEM-ABC demonstrates that the DDMs of FE-BI-MLMFA have essential advantages over those of FEM-ABC. Various numerical experiments confirm the accuracy, efficiency, and flexibility of the nonconformal DDM of FE-BI-MLFMA, which is the CE-based FETI-DP DDM with DTC connecting FEM and BI. [ABSTRACT FROM AUTHOR]

In this paper, we are concerned with the following semilinear Schrödinger equation with electromagnetic fields and critical growth for sufficiently large , where , and its zero set is not empty, is the critical Sobolev exponent, is a constant such that the operator might be indefinite but is non-degenerate. Using variational method and modified Nehari-Pankov method, we prove the equation admits a least energy solution which localizes near the potential well . The results we obtain here extend the corresponding results for the Schrödinger equation which involves critical growth but does not involve electromagnetic fields. [ABSTRACT FROM AUTHOR]

This paper proposes a robust frequency-domain method to tune the d–q decoupled control system used in Modular Multilevel Converter-type Voltage Source Converter (MMC-VSC) systems. A linearized state-space model of the MMC-VSC system is developed and used to calculate the stability-related frequency-domain attributes. The controller design problem is formulated as an optimization problem. In this paper, the simulated annealing optimization technique is applied to find the proportional-integral (PI) controller parameters that give desired damping for the oscillatory modes and desired values for decaying exponential modes. The efficacy of this method is tested on the electromagnetic transient model of a two-terminal MMC-VSC system on the real-time digital simulators, and the results are provided in this paper. Finally, tuned controller parameters for different ac system strengths are discussed and it is shown that this mathematical model is suitable to tune the PI-controller parameters for MMC-VSC systems connected to strong as well as weak ac networks. [ABSTRACT FROM AUTHOR]

In this paper, the characteristics of the electromagnetic noise radiated by an external rotor in-wheel motor (IWM) are investigated with the Doppler effect taken into consideration. First, Maxwell stress tensor method is employed to derive electromagnetic forces on the magnet surface. The effect of common current harmonics is also analyzed. Then, a structural model of the rotor is built and modal test is conducted to validate the model. Nodal forces, which are calculated by finite element method, are transferred from the electromagnetic mesh to the structural model for further vibration prediction. Finally, boundary element method is used to calculate the noise radiated by the rotor. In particular, the Doppler effect is considered. The calculated results are validated by the noise test. It is found that the end cap contributes more to the overall noise than the shell, and obvious sound directivity appears in the noise of the IWM. The noise measured perpendicular to the outer end cap is larger than that measured in other directions. In addition, the Doppler effect would induce additional side-frequency components around high-frequency peaks in the external rotor motor. [ABSTRACT FROM PUBLISHER]

It is popular to use moving elements to improve heating uniformity during microwave heating under some situations. However, it is still a challenge to simulate moving elements during microwave heating due to the complexity of mathematical modeling. In this paper, a novel continuous algorithm based on implicit function and level set methods is developed to compute this heating process. By introducing the implicit function and level set methods, the moving region’s properties are set as a function of space coordinate and time, which means that the movement of the elements is represented by the variation of the parameters. In addition, with the coordinate transformation, the coupling process of electromagnetic field and heat transfer in microwave heating can be performed. A 2-D applicator model and a 3-D applicator model with a rotating turntable are used to illustrate the proposed method in detail. Experiments are also conducted to testify the validity of the proposed method. The results obtained by the proposed method are in accordance with those obtained by experiments. Moreover, compared with conventional methods, the proposed method is more accurate and efficient. [ABSTRACT FROM AUTHOR]

Recently, some authors have shown that a DNA molecule produces electromagnetic signals and communicates with other DNA molecules or other molecules. In fact, a DNA acts like a receiver or transmitter of radio waves. In this paper, we suggest a mathematical model for the DNA molecule and use of its communication to cure some diseases like cancer. In this model, first, by using concepts from string theory and M-theory, we calculate the energy of a DNA in terms of interactions between free electrons and bound electrons. We show that when a DNA is damaged, its energy changes and an extra current is produced. This extra current causes the electromagnetic signals of a damaged DNA molecule to be different when compared to the electromagnetic signals of a normal DNA molecule. The electromagnetic signals of a damaged DNA molecule induce an extra current in a normal DNA molecule and lead to its destruction. By sending crafted electromagnetic signals to normal DNA molecules and inducing an opposite current with respect to this extra current, we can prevent the destruction of normal DNA. Finally, we argue that the type of packing of DNA in chromosomes of men and women is different. This causes radiated waves from DNAs of men and women to have opposite signs and cancel the effect of each other in a pair. Using this property, we suggest another mechanism to cancel the effect of extra waves, which are produced by DNAs in cancer cells of a male or a female, by extra waves which are produced by DNAs in similar cells of a female or a male and prevent the progression of the disease. [ABSTRACT FROM AUTHOR]

The present paper discusses a mathematical model of 3D compressible, laminar flame flow, considering the Lorentz force action on the development of fuel combustion in a cylindrical pipe. The combustion process is modelled with Arrhenius kinetics using two exothermic chemical reactions. A system of non-stationary partial differential equations with seven unknown functions is analyzed. For the inviscid 2D axisymmetric swirling flow approximation, the implicit finite difference scheme in time with upwind differences in space and the alternating direction method are used. The results of numerical simulation are confirmed by the results of the experimental study of electromagnetic field effect on the thermo-chemical conversion of a biomass mixture (straw+wood). [ABSTRACT FROM AUTHOR]

SUMMARY To realize fast electromagnetic field analysis, the parallelization technique has been often introduced into the preconditioned Krylov subspace method. When the multicolor ordering is applied to parallelization of forward and backward substitution, the elapsed time of matrix calculation might increase owning to the increment of bandwidth. Therefore, the block-multicolor ordering based on the level structure arising in reverse Cuthill-McKee ordering has been developed. The validity of developed method was demonstrated on the parallelized incomplete-Cholesky-preconditioned conjugate gradient method. In this paper, the parallelization performance of preconditioned minimized residual method based on the three-term recurrence formula of the CG-type (MRTR) method supported by developed ordering is investigated. Furthermore, the affinity of developed ordering or cache-cache elements technique for parallelized forward and backward substitution in Eisenstat's technique is particularly examined. [ABSTRACT FROM AUTHOR]

Solid nano-structures exhibiting fast ion transport (cations moving in anionic crystal structures) are becoming increasingly relevant in industrial applications. However, it is challenging to model their mechanics due to the presence of electromagnetic couplings. In this paper, a mathematical, physical, and computational framework is introduced, for a cation particle moving through an anion sub-lattice structure in the presence of two electromagnetic fields: an external electromagnetic field; and a self-induced electromagnetic field coming from back-reaction phenomena caused by the relative movement of cations with respect to the mentioned structure. Our approach seeks to incorporate magnetic effects, such as magnetic induction and spin of cations, which are not incorporated in other models, mainly due to the intrinsic difficulty of 3D effects. We propose a quantum mechanical formalism based on a Schrödinger-type equation, where a wave function models the behavior of a cation in presence of an external electromagnetic potential, coupled with transient and self-induced electromagnetic effects. To solve the model, a space–time coupled numerical scheme is presented, which allows the possibility of time-evolving electromagnetic effects. The technique uses finite-elements in space and time-marching schemes in time. While a time-explicit marching scheme is used to update the magnetic and electric-potential fields, a time-implicit marching scheme is used to solve the coupled Schrödinger equation. This strategy allows us to update the electromagnetic contributions and wave functions at each time-step. Numerical examples in one and two spatial dimensions (and evolving in time) have been implemented for some meaningful models obtained from nanoionics literature. [ABSTRACT FROM AUTHOR]

This paper is concerned with the scattering and field enhancement of a narrow slit perforated in a slab of perfect conductor. We demonstrate that the enhancement of the electromagnetic field for such a configuration can be induced by either Fabry-Perot type scattering resonances or a certain nonresonant effect in the quasi-static regime. We derive the asymptotic expansions of Fabry-Perot type resonances and quantitatively analyze the field enhancement at the resonant frequencies, for which both the enhancement order and the shapes of resonant modes are precisely characterized. The field enhancement at nonresonant frequencies in the quasi-static regime is also investigated. It is shown that the fast transition of the magnetic field in the slit induces strong electric field enhancement. [ABSTRACT FROM AUTHOR]

Permittivity of biological tissue is a critical issue for studying the biological effects of electromagnetic fields. Many theories and experiments were performed to measure or explain the permittivity characteristics in biological tissue. In this paper, we investigate the permittivity parameter in biological tissues via theoretical and experimental analysis. Firstly, we analyze the permittivity characteristic in tissue by using theories on composite material. Secondly, typical biological tissues, such as blood, fat, liver, and brain, are measured by HP4275A Multi-Frequency LCR Meter within 10 kHz to 10 MHz. Thirdly, experimental results are compared with the Bottcher-Bordewijk model, the Skipetrov equation, and the Maxwell-Gannett theory. From the theoretical perspective, blood and fat are regarded as the composition of liver and brain because of the high permittivity in blood and the opposite in fat. Volume fraction of blood in liver and brain is analyzed theoretically, and the applicability and the limitation of the models are also discussed. These results benefit further study on local biological effects of electromagnetic fields. [ABSTRACT FROM AUTHOR]

Determination of the distribution of electromagnetic energy inside electrically large enclosed spaces is important in many electromagnetic compatibility applications, such as certification of aircraft and equipment shielding enclosures. The field inside such enclosed environments contains a dominant diffuse component due to multiple randomizing reflections from the enclosing surfaces. The power balance technique has been widely applied to the analysis of such problems; however, it is unable to account for the inhomogeneities in the field that arise when the absorption in the walls and contents of the enclosure is significant. In this paper, we show how a diffusion equation approach can be applied to modeling diffuse electromagnetic fields and evaluate its potential for use in electromagnetic compatibility applications. Two canonical examples were investigated: a loaded cavity and two cavities coupled by a large aperture. The predictions of the diffusion model were compared to measurement data and found to be in good agreement. The diffusion model has a very low computational cost compared to other applicable techniques, such as full-wave simulation and ray-tracing, offering the potential for a radical increase in the efficiency of the solution high frequency electromagnetic shielding problems with complex topologies. [ABSTRACT FROM PUBLISHER]

The aim of this paper was to estimate fermentation kinetic parameters to develop a mathematical model of the bioethanol production under magnetic field effect. Thus, a non-structured mathematical model was developed considering three non-lineal kinetic models typically known as Levenspiel, Aiba, Jerusalimsky, which take into account inhibitory effects of the high product concentration on yeasts. The non-lineal differential equations system solution was carried out by MatLab software using the Runge-Kutta fourth-order multivariable method. This method was improved through a replication scheme coupled with Newton-Raphson method modified with a damping Broyden parameter. Experimental data on substrate consumption, biomass formation and ethanol production were collected at magnetic field intensities (H) of 414, 796 and 1216 A/cm during 16 h of fermentation. Consequently, the adjusted model for biomass, consumed substrate and bioethanol produced allowed us to correlate fermentation kinetic parameters with the magnetic field. The best result was observed when Jerusalimsky model modified with a magnetic field parameter was considered, because the RMSD order and R-square correlation coefficient were around 10−3 and higher than 0.95, respectively. These results are important to understand the phenomenological behavior of this unconventional bioprocess and be helpful to further sensibility analysis and scale up of the bioethanol production assisted by electromagnetic field. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper deals with some aspects of formulation and implementation of a broadband algorithm with build-in analysis of some dispersive media. The construction of the finite element method (FEM) based on direct integration of Maxwell's equations and solution of some additional convolution integrals is presented. The broadband, fractional model of permittivity is approximated by a set of some relaxation sub-models. The properties of the 3D time-dependent formulation of the FEM algorithm are determined using a benchmark problem with the Cole-Cole and the Davidson-Cole models. Several issues associated with the implementation and some constraints of the broadband finite element algorithm are presented. [ABSTRACT FROM AUTHOR]

The paper deals with the interaction between electromagnetic and hydrodynamic field of electromagnetic thruster. The mathematical model of the interaction defines the constant ruler of MHD interaction. [ABSTRACT FROM AUTHOR]

The computation of electromagnetic (EM) fields for 1-Dlayered earth model requires evaluation of Hankel transform. In this paper we propose a stable algorithm for the first time that is quite accurate and fast for numerical evaluation of the Hankel transform using Sine-Cosine wavelets arising in seismology. We have projected an approach depending on separating the integrand rf ( r ) J ν ( pr ) into two components; the slowly varying components rf ( r ) and the rapidly oscillating component J ν ( pr ). Then either rf ( r ) is expanded into wavelet series using Sine-Cosine wavelets orthonormal basis and truncating the series at an optimal level or approximating rf ( r ) by a quadratic over the subinterval using the Filon quadrature philosophy. The solutions obtained by proposed Sine-Cosine wavelet method applied on 5 test functions indicate that the approach is easy to implement and computationally very attractive. We have supported a new efficient and stable technique based on compactly supported orthonormal wavelet bases. [ABSTRACT FROM AUTHOR]

The paper presents analysis of surface induction hardening of a cylindrical element made of steel 38Mn6. The mathematical model of the non-stationary process is elaborated. Calculations of coupled electromagnetic and temperature fields are provided by means of the Flux 2D software. Computations are compared with the measurements realized at the laboratory stand located in the Silesian University of Technology. The expected hardness distribution within the surface layer is noticed. [ABSTRACT FROM AUTHOR]

Solid dielectrics have been widely investigated as potential attractive candidates in compact portable pulsed-power systems. Slow-wave structure with good dispersion characteristics and broad transmission band can be used to increase the pulse duration while the size of pulse-forming line (PFL) decreases. In this paper, we present two different slow-wave structures, the tape helix for coaxial-line and the meander-line structure for the planar line, to increase the pulse duration of solid PFLs based on dispersion analysis. At first, the characteristic impedances, electric length, and dispersion curve of the PFL with the slow-wave structure are calculated by the electromagnetic dispersion theory. Based on the theoretical calculations, the PFLs are designed and simulated by the electromagnetic field tool. Finally, some test results on the PFLs are introduced. Currently, both the Al2O3 ( \varepsilon r= 9.3 ) helical PFL and the glass–ceramic ( \varepsilon r = 225 ) meander-line PFL can deliver a pulsewith 50-ns width, of which the dimension is \phi ~67~\mathrm mm \times 305 mm and 95~\mathrm mm \times 95~\mathrm mm\times 4 mm, respectively. [ABSTRACT FROM PUBLISHER]

The aim of this paper is to highlight the capabilities of a new hybrid analytical modeling (HAM) approach for the analysis and design of various electromagnetic structures. After an introduction, where the aim of the development of this modeling approach is presented, the modeling approach is described. The new HAM is based on a strong coupling of the magnetic equivalent circuits method and analytical models (AMs). The AM, based on the formal solution of Maxwell’s equations, is established thanks to the separation of variables method. The HAM is applied to different permanent magnet electric machine structures, and the results are validated extensively by comparison with the finite-element analyses. [ABSTRACT FROM AUTHOR]

Numerical techniques for calculating electromagnetic fields within three-dimensional surfaces are computationally intensive. Therefore, this paper presents the application of a mode-matching technique developed for analyzing electromagnetic scattering from periodic comb surfaces illuminated by a plane wave. A set of linear equations has been developed to calculate mode coefficients of the field distribution for both E- and H-polarized incident waves. Analysis is performed for two cases where the comb thickness is either infinitely thin or of a finite thickness. The technique is shown to accurately predict both field intensities within the near-field of the periodic surface and far-field scattering patterns. Results are compared to those obtained using the finite integration techniques (FIT) implemented in CST Microwave Studio. Furthermore, numerical results are compared to measurements of an aluminum prototype. Additional far-field scattering measurements using a bi-static system provide additional confidence in CST simulations and the mode-matching methods presented here. [ABSTRACT FROM PUBLISHER]

Most studies presented to date in the use of the marine controlled source electromagnetic (CSEM) method to detect hydrocarbons analyze the homogeneous reservoir models of isotropic or anisotropic resistivity. In the present paper, we use 3D vector finite element modeling to calculate the electromagnetic response from various inhomogeneous reservoir models of a complex structure. Also, we study the electromagnetic field propagation inside the homogeneous and inhomogeneous 3D reservoirs, as well as the problem of equivalence of inhomogeneous and homogeneous reservoirs. [ABSTRACT FROM AUTHOR]

SUMMARY In this paper, representations of a perfectly conducting thin wire and an imperfectly conducting medium in the transmission line modeling (TLM) calculation are briefly explained. Then, the method is applied to analyzing surge responses of a vertical parallelepiped grounding electrode and a square-loop grounding electrode. Surge responses calculated using the TLM method agree reasonably well with the corresponding responses measured and calculated using the finite-difference time-domain method. It is probably the first time that surge responses of grounding electrodes have been analyzed reasonably accurately using the TLM method. [ABSTRACT FROM AUTHOR]

Electromagnetic method to measure water flow has been known for nearly 180 years. This paper presents how the method has undergone development and describes in detail the most common electromagnetic flowmeters used for open channels. It also presents specific methods of signal processing used in this type of flowmeters. The analysis is associated directly with the relevant types of induced magnetic field. Some of the analyzed types of magnetic fields considered are sine waves and bipolar rectangular fields. The concept of low-energy electromagnetic flow meter was introduced as part of deliberations concerning current development trends. [ABSTRACT FROM AUTHOR]

Due to the various physical mechanisms of interaction between a worker's body and the electromagnetic field at various frequencies, the principles of numerical simulations have been discussed for three areas of worker exposure: to low frequency magnetic field, to low and intermediate frequency electric field and to radiofrequency electromagnetic field. This paper presents the identified difficulties in applying numerical simulations to evaluate physical estimators of direct and indirect effects of exposure to electromagnetic fields at various frequencies. Exposure of workers operating a plastic sealer have been taken as an example scenario of electromagnetic field exposure at the workplace for discussion of those difficulties in applying numerical simulations. The following difficulties in reliable numerical simulations of workers' exposure to the electromagnetic field have been considered: workers' body models (posture, dimensions, shape and grounding conditions), working environment models (objects most influencing electromagnetic field distribution) and an analysis of parameters for which exposure limitations are specified in international guidelines and standards. [ABSTRACT FROM AUTHOR]

In this paper, we deal with the existence and multiplicity of solutions for perturbed Schrödinger equation with electromagnetic fields and critical nonlinearity in RN: -ε²ΔAu(x) + V(x)u(x) = |u|2*-2u + h(x, |u|²)u for all x ∈ RN, where ∇Au(x) := (∇ + iA(x))u, V(x) is a nonnegative potential. By using Lions' second concentration compactness principle and concentration compactness principle at infinity to prove that the (PS)c condition holds locally and by variational method, we show that this equation has at least one solution provided that ε < ε, for any m ∈ N, it has m pairs of solutions if ε < εm, where ε and εm are sufficiently small positive numbers. [ABSTRACT FROM AUTHOR]

Through-the-Earth (TTE) communication systems require minimal infrastructure to operate. Hence, they are assumed to be more survivable and more conventional than other underground mine communications systems. This survivability is a major advantage for TTE systems. In 2006, Congress passed the Mine Improvement and New Emergency Response Act (MINER Act), which requires all underground coal mines to install wireless communications systems. The intent behind this mandate is for trapped miners to be able to communicate with surface personnel after a major accident-hence, the interest in TTE communications. To determine the likelihood of establishing a TTE communication link, it would be ideal to be able to predict the apparent conductivity of the overburden above underground mines. In this paper, all 94 mine TTE measurement data collected by Bureau of Mines in the 1970s and early 1980s, are analyzed for the first time to determine the apparent conductivity of the overburden based on three different models: a homogenous half-space model, a thin sheet model, and an attenuation factor or Q-factor model. A statistical formula is proposed to estimate the apparent earth conductivity for a specific mine based on the TTE modeling results given the mine depth and signal frequency. [ABSTRACT FROM AUTHOR]

In this paper we present a finite element model in frequency domain which computes the Lorentz force that drives an electromagnetic forming (EMF) process. The only input data required are the electrical parameters of the capacitor bank, the coil and the work piece. The main advantage of this approach is that it provides an explicit relation between the parameters of the EMF process and the frequency of the discharge, which is a key parameter in the design of an optimum EMF system. The method is computationally efficient because it only requires to solve time-harmonic Maxwell's equations for a few frequencies and it can be very useful for coil design and for testing modeling conditions on complex three-dimensional geometries. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a planar Schottky varistor diode is studied and modeled by equivalent circuit method and three dimensional full wave electromagnetic (3D-EM) method, respectively. The diode's equivalent circuit is extracted from millimeter-wave small-signal S-parameter measurements. Since the package of the diode influences the electromagnetic field distribution at millimeter and sub-millimeter wavelengths, a 3D-EM model and an improved equivalent circuit model is applied to describe the field precisely. The simulated results of equivalent circuit, improved equivalent circuit and 3D-EM model are compared with the measured results. In addition, the effects caused by silver paste conductive adhesive are considered in 3D-EM model and improved equivalent circuit model. The results show that both the 3D-EM model and improved equivalent circuit model have good S-parameter consistency with measured results. [Copyright &y& Elsevier]

The paper presents the results of an experimental study of heating and the structural resultant changes of source rocks under the influence of the electromagnetic field in the microwave and radio-frequency ranges. The samples from the Bazhenov Formation (West Siberia, Russia) and the Domanic Formation (Ural, Russia) have been tested. It is shown that samples from these formations demonstrate very different heating rates at the same electromagnetic field parameters and the their heating rate depends on the type of the electromagnetic field (radio-frequency or microwave) applied. The temperature of the Bazhenov Formation samples reaches 300 °C within one hundred seconds of the microwave treatment but it slowly rises to 200 °C after twelve minutes of the radio-frequency influence. The samples of the carbonate Domanic Formation heat up more slowly in the microwave field (within two hundred seconds) and to lower temperatures in the radio-frequency (150 °C) than the Bazhenov Formation samples. The study of the structure of the samples before and after experiments on the electromagnetic treatment shows fracture formation during the heating process. Numerical simulations of heating dynamics of source rock samples have been based on a simple mathematical model of the electromagnetic influence and main features of heating for different types of source rock have been revealed. The opportunities for application of electromagnetic heating for oil source rock recovery are discussed. [ABSTRACT FROM AUTHOR]