Behavior Of Electromagnetic Field Research Articles

Polyharmonic Representation of the Electromagnetic Field Generated by an Oscillating Particle near a Dispersive Bulk

This study introduces a polyharmonic framework for analyzing the electromagnetic (EM) field generated by an oscillating point charge near a dispersive bulk of size comparable to the wavelength under study. We critically evaluate traditional approaches such as Liénard-Wiechert, Landau, and Raimond, and propose a Fourier representation of sources that simplifies numerical implementation and enhances analytical clarity. Our method effectively addresses the limitations of conventional models and is applicable to both relativistic and non-relativistic scenarios. It includes the oscillating point dipole fields, providing a comprehensive understanding of the EM field behavior. The Finite Element Method (FEM) is employed for numerical analysis, demonstrating the method’s adaptability to complex geometries. While offering significant insights, this study acknowledges certain limitations and outlines directions for future research.

Generic Behavior of Electromagnetic Fields of Regular Rotating Electrically Charged Compact Objects in Nonlinear Electrodynamics Minimally Coupled to Gravity

Regular rotating electrically charged compact objects are described by nonlinear electrodynamics minimally coupled to gravity in a self-consistent way and without additional assumptions on the relation between the electromagnetic field and gravity. The electromagnetic fields obey the system of four source-free nonlinear equations for the electromagnetic tensor Fμν, with only two independent components due to spacetime symmetry determined by the algebraic structure of electromagnetic stress–energy tensors (pr=−ρ). In this paper, we present, for an arbitrary gauge-invariant Lagrangian, the general regular solution and generic behavior of electromagnetic fields, including the generic features of the Lagrange dynamics, for regular rotating electrically charged black holes and electromagnetic spinning solitons.

Application of Herglotz’s variational principle to electromagnetic systems with dissipation

This work applies the contact formalism of classical mechanics and classical field theory, introduced by Herglotz and later developed in the context of contact geometry, to describe electromagnetic systems with dissipation. In particular, we study an electron in a non-perfect conductor and a variation of the cyclotron radiation. In order to apply the contact formalism to a system governed by the Lorentz force, it is necessary to generalize the classical electromagnetic gauge and add a new term in the Lagrangian. We also apply the k-contact theory for classical fields to model the behavior of electromagnetic fields themselves under external damping. In particular, we show how the theory describes the evolution of electromagnetic fields in media under some circumstances. The corresponding Poynting theorem is derived. We discuss its applicability to the Lorentz dipole model and to a highly resistive dielectric.

Long time dynamics and upper semi-continuity of attractors for piezoelectric beams with nonlinear boundary feedback

A system of boundary-controlled piezoelectric beam equations, accounting for the interactions between mechanical vibrations and the fully-dynamic electromagnetic fields, is considered. Even though electrostatic and quasi-static electromagnetic field approximations of Maxwell’s equations are sufficient for most models of piezoelectric systems, where the magnetic permeability is completely discarded, the PDE model considered here retains the pronounced wave behavior of electromagnetic fields to accurately describe the dynamics for the most piezoelectric acoustic devices. It is also crucial to investigate whether the closed-loop dynamics of the fully-dynamic piezoelectric beam equations, with nonlinear state feedback and nonlinear external sources, is close to the one described by the electrostatic/quasi-static equations, when the magnetic permeability μ is small. Therefore, the asymptotic behavior is analyzed for the fully-dynamic model at first. The existence of global attractors with finite fractal dimension and the existence of exponential attractors are proved. Finally, the upper-semicontinuity of attractors with respect to magnetic permeability to the ones of the electrostatic/quasi-static beam equations is shown.

Universal Statistical Tradeoffs for Shielding Effectiveness Evaluation of Electrically Large Enclosures in Reverberation Chambers

Shielding effectiveness (SE) evaluation of electrically large enclosures within reverberation chambers (RCs) is standardized procedure for electromagnetic compatibility (EMC) applications. In this work the potential relationship between SE and electromagnetic resonances have been investigated with respect to the ambiguity in definition of SE for the international standards, e.g., IEC 61000-4-21 or IEEE Std 299.1. From a statistical point of view, we derive the expansions of SE defined by the ratio of the maxima and the averages respectively. To evaluate SE more prudently as well as to obtain a much smaller uncertainty, we can make the tradeoffs for SE, which should be defined as the ratio of the averages for the overmoded frequency, and the ratio of the maxima for the undermoded using a common criterion aimed to discriminate the electromagnetic field behavior between the undermoded and the overmoded, and also verify the corresponding results by numerical simulations and measurement performed in RC.

A New Formulation of Maxwell’s Equations

In this paper, new forms of Maxwell’s equations in vector and scalar variants are presented. The new forms are based on the use of Gauss’s theorem for magnetic induction and electrical induction. The equations are formulated in both differential and integral forms. In particular, the new forms of the equations relate to the non-stationary expressions and their integral identities. The indicated methodology enables a thorough analysis of non-stationary boundary conditions on the behavior of electromagnetic fields in multiple continuous regions. It can be used both for qualitative analysis and in numerical methods (control volume method) and optimization. The last Section introduces an application to equations of magnetic fluid in both differential and integral forms.

Theoretical Study of the Input Impedance and Electromagnetic Field Distribution of a Dipole Antenna Printed on an Electrical/Magnetic Uniaxial Anisotropic Substrate

The present work considers the investigation of the effects of both electrical and magnetic uniaxial anisotropies on the input impedance, resonant length, and fields distribution of a dipole printed on an anisotropic grounded substrate. In this study, the associated integral equation, based on the derivation of the Green’s functions in the spectral domain, is numerically solved employing the method of moments. In order to validate the computing method and the evaluated calculation code, numerical results are compared with available data in the literature treating particular cases of electrical uniaxial anisotropy; reasonable agreements are reported. Novel results of the magnetic uniaxial anisotropy effects on the input impedance and the evaluated electromagnetic field are presented and discussed. This work will serve as a stepping stone for further works for a better understanding of the electromagnetic field behavior in complex anisotropic and bi-anisotropic media.

Modeling electromagnetic processes in direct current electroslag remelting

This article is devoted to the study of an important problem which arises during electroslag remelting when alternating current is converted to direct current. This problem arose in the second half of the last century but has not yet been solved, at least theoretically. However, experimental attempts to resolve it have always existed and continue to this day; moreover, they are quite successful. Due to the difficulties of studying physical phenomena in such processes, it is prudent to use mathematical modeling, in particular, using Maxwell’s theory of electromagnetism. The solution to the problem is to find the features of the behavior of electromagnetic fields in pools of slag melt. We analyzed the literature on this topic and formulated a number of hypotheses. Examination of these hypotheses using mathematical methods will allow for greater success in the direction of accepted assumptions. Rejected hypotheses are not subject to further consideration, thereby achieving significant savings in material and financial resources. Modeling is based on the Maxwell system of electromagnetism. The calculations revealed significant anisotropy in the redistribution of the main technological parameters, which corresponds to experimental data. Non-coaxialness sources of electric current lead to an increase in this anisotropy phenomenon.

Multiple Fano Resonances with Tunable Electromagnetic Properties in Graphene Plasmonic Metamolecules

Multiple Fano resonances (FRs) can be produced by destroying the symmetry of structure or adding additional nanoparticles without changing the spatial symmetry, which has been proved in noble metal structures. However, due to the disadvantages of low modulation depth, large damping rate, and broadband spectral responses, many resonance applications are limited. In this research paper, we propose a graphene plasmonic metamolecule (PMM) by adding an additional 12 nanodiscs around a graphene heptamer, where two Fano resonance modes with different wavelengths are observed in the extinction spectrum. The competition between the two FRs as well as the modulation depth of each FR is investigated by varying the materials and the geometrical parameters of the nanostructure. A simple trimer model, which emulates the radical distribution of the PMM, is employed to understand the electromagnetic field behaviors during the variation of the parameters. Our proposed graphene nanostructures might find significant applications in the fields of single molecule detection, chemical or biochemical sensing, and nanoantenna.

Design and Modeling of a Radiofrequency Coil Derived from a Helmholtz Structure

This paper focuses on radiofrequency (RF) coils that can produce a high electromagnetic field homogeneity to be used for magnetic resonance imaging (MRI) applications. The proposed structure is composed of four wire loops symmetrically located on an ellipsoidal surface. The main objective of this work is to improve field homogeneity compared to a standard Helmholtz coil. Numerical simulation was carried out to assess the RF electromagnetic field behavior of the proposed coil. Different electrical modeling and simulations were investigated, particularly the study of the whole modeling of the proposed structure taking into account all the couplings between the loops. The proposed coil was evaluated and compared with the standard Helmholtz coil. Simulation and experimental results confirmed the good performance of the developed coil in terms of electromagnetic field homogeneity, efficiency, sensitivity, and quality factor.

Electromagnetic field behavior of 3D Maxwell's equations for chiral media

This article focuses on numerically studying the eigenstructure behavior of generalized eigenvalue problems (GEPs) arising in three dimensional (3D) source-free Maxwell's equations with magnetoelectric coupling effects which model 3D reciprocal chiral media. It is challenging to solve such a large-scale GEP efficiently. We combine the null-space free method with the inexact shift-invert residual Arnoldi method and MINRES linear solver to solve the GEP with a matrix dimension as large as 5,308,416. The eigenstructure is heavily determined by the chirality parameter γ. We show that all the eigenvalues are real and finite for a small chirality γ. For a critical value γ=γ⁎, the GEP has 2×2 Jordan blocks at infinity eigenvalues. Numerical results demonstrate that when γ increases from γ⁎, the 2×2 Jordan block will first split into a complex conjugate eigenpair, then rapidly collide with the real axis and bifurcate into positive (resonance) and negative eigenvalues with modulus smaller than the other existing positive eigenvalues. The resonance band also exhibits an anticrossing interaction. Moreover, the electric and magnetic fields of the resonance modes are localized inside the structure, with only a slight amount of field leaking into the background (dielectric) material.

Local Dosimetry Applied to Wireless Power Transfer Around 10 MHz: Dependence on EM Parameters and Tissues Morphology

In this paper, we analyze in detail the local exposure induced inside the human body by a generic nonradiative resonant wireless power transfer (WPT) system operating at 10 MHz. The impact of electromagnetic (EM) properties of biological tissue, as well as of the body geometry and size on local distribution of the EM field inside the body, is investigated using the finite integration technique. To this end, three high-resolution anatomical virtual family human body models have been employed, i.e., adult male and female, as well as a child model. The correlation of the distribution and location of maximum of the electric field ( E ) inside the body with the tissues intrinsic impedance contrast shows the ability to interpret the EM field behavior locally inside the body; the increase (decrease) of the intrinsic impedance from a tissue to another leads to the increase (decrease) of the E -field intensity. The location of the maximum inside the body is shown to be a function of the magnetic field ( H ) polarization inside the body. For instance, it appears in deeper tissues at locations where the H -field polarization is perpendicular compared to parallel to the body. Higher exposure levels are observed in adults compared to children in terms of E $_{99}$ (up to 60%) and SAR $_{10g}$ (up to 100%). In the case of J $_{1\text{cm}^2}$ and SAR $_{wb}$ , the peak values are higher in the female model, followed by the child and male (maximum variation of 31% and 10%, respectively).

Numerical Investigation and Experimental Validation of Motion and Distribution of Nonmetallic Inclusions in Argon Protection Electroslag Remelting Process

A transient coupled mathematical model has been proposed to predict the motion and distribution of nonmetallic inclusions in the electroslag remelting process. The electromagnetic field, temperature distribution, flow pattern, solidification, and inclusion behavior were solved simultaneously. The Euler-Lagrange approach was used to describe the interaction between continuous phase and inclusions. The discrete phase model (DPM) was adopted to track the particles acted by a number of forces. An experiment under argon protection was implemented, and it agrees well with the simulation. The effect of inclusion diameter was also discussed. The experiment result shows that the typical inclusions in final ingot are Al2O3 core surrounded by an outer sulfide layer and pure MnS inclusions. The total area of inclusions increases from center toward ingot surface, while the average equivalent diameter decreases. The simulated result indicates a denser distribution of inclusions locations at the region ranging from 0.7 to 0.9 radii. Few inclusions are entrapped near the mold due to the strong descending flow. Moreover, the inclusion amount increases with height. The total amounts of inclusions with diameter of 2 μm, 5 μm, and 10 μm in ingot are 2199, 1871, and 1704, respectively. The imposed buoyancy and floatation contribute to this phenomenon.

Electrochemical model of euglena sanguinea ehrenberg stimulated with multi-level electromagnetic fields

This research aimed at studying the property of Euglena Sanguinea Ehrenberg (E. sanguinea) before and after being stimulated by multi-level electromagnetic fields (MLEM). After the stimulation, it was found that physical properties were changed, i.e., cell membrane and components deformed. Main biochemical compositions were changed in accordance with new electrochemical equation which was estimated from FTIR bands. Moreover, the estimated electrical results before and after being stimulated, i.e., impedance and complex relative permittivity of main biochemical compositions from extraction, were then measured, simulated, and compared by means of Cole-Cole plot technique which yielded the statistic correlation 0.89 at 95% confidence level. Semi-circle impedance was related to complex relative permittivity as its value decreased with the increasing frequency. These were the information for designing the new electrical equivalent circuit model of E. sanguinea with MLEM to explain many phenomena in cell. The relationship between energy from MLEM system and bond energy of main biochemical compositions of E. sanguinea as well as between electromagnetic field behaviors of MLEM system which stimulated to cell and induced voltage transmitted through each biochemical compositions of E. sanguine were also identified.

ELECTROCHEMICAL MODEL OF Euglena sanguinea Ehrenberg STIMULATED WITH MULTI-LEVEL ELECTROMAGNETIC FIELDS

This research aimed at studying the property of Euglena Sanguinea Ehrenberg (E. sanguinea) before and after being stimulated by multi-level electromagnetic fields (MLEM). After the stimulation, it was found that physical properties were changed, i.e., cell membrane and components deformed. Main biochemical compositions were changed in accordance with new electrochemical equation which was estimated from FTIR bands. Moreover, the estimated electrical results before and after being stimulated, i.e., impedance and complex relative permittivity of main biochemical compositions from extraction, were then measured, simulated, and compared by means of Cole-Cole plot technique which yielded the statistic correlation 0.89 at 95% confidence level. Semi-circle impedance was related to complex relative permittivity as its value decreased with the increasing frequency. These were the information for designing the new electrical equivalent circuit model of E. sanguinea with MLEM to explain many phenomena in cell. The relationship between energy from MLEM system and bond energy of main biochemical compositions of E. sanguinea as well as between electromagnetic field behaviors of MLEM system which stimulated to cell and induced voltage transmitted through each biochemical compositions of E. sanguine were also identified.

Poloidal and toroidal plasmons and fields of multilayer nanorings

Composite and janus type metallo-dielectric nanoparticles are increasingly considered as a means to control the spatial and temporal behavior of electromagnetic fields in diverse applications such as coupling to quantum emitters, achieve invisibility cloaks, and obtain quantum correlations between qubits. We investigate the surface modes of a toroidal nano-structure and obtain the canonical plasmon dispersion relations and resonance modes for arbitrarily layered nanorings. Unlike particle plasmon eigenmodes in other geometries, the amplitudes of the eigenmodes of tori exhibit a distinct forward and backward coupling. We present the plasmon dispersion relations for several relevant toroidal configurations in the quasistatic limit and obtain the dominant retarded dispersion relations of a single ring for comparison, discuss mode complementarity and hybridization, and introduce two new types of toroidal particles in the form of janus nanorings. The resonance frequencies for the first few dominant modes of a ring composed of plasmon supporting materials such as gold, silver, and aluminum are provided and compared to those for a silicon ring. A generalized Green's function is obtained for multilayer tori allowing for calculation of the scattering response to interacting fields. Employing the Green's function, the scalar electric potential distribution corresponding to individual poloidal and toroidal modes in response to an arbitrarily polarized external field and the field of electrons is obtained. The results are applied to obtain the local density of states and decay rate of a dipole near the center of the torus.

Modeling of Antenna for Deep Target Hydrocarbon Exploration

Nowadays control source electromagnetic method is used for offshore hydrocarbon exploration. Hydrocarbon detection in sea bed logging (SBL) is a very challenging task for deep target hydrocarbon reservoir. Response of electromagnetic (EM) field from marine environment is very low and it is very difficult to predict deep target reservoir below 2km from the sea floor. This work premise deals with modeling of new antenna for deep water deep target hydrocarbon exploration. Conventional and new EM antennas at 0.125Hz frequency are used in modeling for the detection of deep target hydrocarbon reservoir. The proposed area of the seabed model (40km ´ 40km) was simulated by using CST (computer simulation technology) EM studio based on Finite Integration Method (FIM). Electromagnetic field components were compared at 500m target depth and it was concluded that Ex and Hz components shows better resistivity contrast. Comparison of conventional and new antenna for different target depths was done in our proposed model. From the results, it was observed that conventional antenna at 0.125Hz shows 70% ,86% resistivity contrast at target depth of 1000m where as new antenna showed 329%, 355% resistivity contrast at the same target depth for Ex and Hz field respectively. It was also investigated that at frequency of0.125Hz, new antenna gave 46% better delineation of hydrocarbon at 4000m target depth. This is due to focusing of electromagnetic waves by using new antenna. New antenna design gave 125% more extra depth than straight antenna for deep target hydrocarbon detection. Numerical modeling for straight and new antenna was also done to know general equation for electromagnetic field behavior with target depth. From this numerical model it was speculated that this new antenna can detect up to 4.5 km target depth. This new EM antenna may open new frontiers for oil and gas industry for the detection of deep target hydrocarbon reservoir (HC)

Study of Nanocomposite Permittivity on the Basis of Magnetite Nanoparticles (Fe3O4) and Polymeric Matrix: Polyethylene and Polystyrene in Electromagnetic Field

This paper deals with the investigation results of nanocomposite permittivity based on magnetite nanoparticles and a polymeric matrix in electromagnetic field. Dependencies of real and imaginary parts of nanocomposite permittivity on the frequency of the electromagnetic field and size and concentration of magnetite nanoparticles have been found, and the dependence of imaginary part of permittivity on the real one has been determined. The Cole-Cole type has the dependence of the imaginary part of permittivity on the real one at high frequencies of electromagnetic field (at small values of the real part of permittivity) and hyperbolic behavior at small frequencies of the electromagnetic field (at large values of the real part of permittivity). Refraction index, loss angle tangent, and penetration depth of the nanocomposite.

Evaluation of Telecommunications Electromagnetic Compatibility with the Use of Three-Dimensional Modeling Technology

Three-dimensional modeling is used as a new way of presenting information about the electromagnetic compatibility of telecommunications infrastructure equipment. We analyzed the problem of modeling of electromagnetic noise waves equipment and communication channels of telecommunications monitoring systems. Conducted the analysis of control problems of telecommunications equipment electromagnetic compatibility. Described the real conditions of installing the electronic equipment in computational complexes. Using tools of 3D-modeling was formed cable route, taking into account the suppression of noise waves, placement of telecommunication devices and checking whether the threshold value of cable susceptibility for all options of its gasket between devices was transcended. It is proposed to study the behavior of electromagnetic fields in the cable lines with shielding cable, electrostatic discharge, providing set of measures for electromagnetic compatibility, to convert created in a three-dimensional environment model in a specialized settlement package. The prospects of the use 4D-, 5D-, 6D-simulation for analysis of the implementation of projects, reduction of operating and electromagnetic compatibility costs.

Lorentz force electrical impedance tomography using magnetic field measurements

In this study, magnetic field measurement technique is investigated to image the electrical conductivity properties of biological tissues using Lorentz forces. This technique is based on electrical current induction using ultrasound together with an applied static magnetic field. The magnetic field intensity generated due to induced currents is measured using two coil configurations, namely, a rectangular loop coil and a novel xy coil pair. A time-varying voltage is picked-up and recorded while the acoustic wave propagates along its path. The forward problem of this imaging modality is defined as calculation of the pick-up voltages due to a given acoustic excitation and known body properties. Firstly, the feasibility of the proposed technique is investigated analytically. The basic field equations governing the behaviour of time-varying electromagnetic fields are presented. Secondly, the general formulation of the partial differential equations for the scalar and magnetic vector potentials are derived. To investigate the feasibility of this technique, numerical studies are conducted using a finite element method based software. To sense the pick-up voltages a novel coil configuration (xy coil pairs) is proposed. Two-dimensional numerical geometry with a 16-element linear phased array (LPA) ultrasonic transducer (1 MHz) and a conductive body (breast fat) with five tumorous tissues is modeled. The static magnetic field is assumed to be 4 Tesla. To understand the performance of the imaging system, the sensitivity matrix is analyzed. The sensitivity matrix is obtained for two different locations of LPA transducer with eleven steering angles from to at intervals of . The characteristics of the imaging system are shown with the singular value decomposition (SVD) of the sensitivity matrix. The images are reconstructed with the truncated SVD algorithm. The signal-to-noise ratio in measurements is assumed 80 dB. Simulation studies based on the sensitivity matrix analysis reveal that perturbations with mm size can be detected up to a 3.5 cm depth.