Maxwell Electromagnetic Field Research Articles

Spherically symmetric electrovac spacetimes in conformal Killing gravity

Recently Harada proposed a third-order gravitational theory for the derivatives of the metric. Mantica and Molinari showed that Harada’s theory may be recast into the form of Einstein’s field equations (EFEs) with an additional source term which is a second-order conformal Killing tensor. Accordingly they named the theory conformal Killing gravity. However, they overlooked the fact that all solutions of the new theory (except those satisfying EFEs) admit a non-trivial second-order Killing tensor. Harada derived an analog of the Schwarzschild solution. Recently Tarciso et al obtained a generalization of Harada’s vacuum solution analogous to the Reissner–Nordström solution. However, like Harada they assumed a restricted form for a static spherically symmetric metric. In this study the most general spherically symmetric static vacuum solution of Harada’s theory and its generalization with a Maxwell electromagnetic field as source were obtained. The validity of Birkhoff’s theorem for static spherically symmetric electrovac fields in conformal Killing gravity is investigated.

Three Serious Mistakes in Einstein’s Original Paper of Special Relativity in 1905

It is revealed in this paper that there were three serious mistakes in the Einstein’s original paper in 1905. Einstein did not prove that the motion equation of classical electromagnetic field could satisfy the invariance of the Lorentz coordinate transformation. The Einstein’s derivations on the formulas of transverse and longitudinal masses, as well as the calculation on the mass-energy relation are wrong. 1. In order to prove that the classical Maxwell electromagnetic field equation satisfied the invariance of Lorentz transformation in free space without charged and current, Einstein introduced the transformations of electromagnetic fields themselves, called the Einstein’s transformations of electromagnetic fields. However, these transformations are completely different from the Lorentz transformations of electromagnetic fields themself, which leads to contradiction and does not hold. 2. For the electromagnetic field equations in non-free space with charge and current, the Einstein’s transformations can not make the electromagnetic fields unchanged under the Lorentz transformation. 3. The constitutive equations of electromagnetic theory in the medium do not satisfy the invariance of the Lorentz transformation too. Therefore, the classical electromagnetic field equations have no the invariance of the Lorentz transformation actually, and the most important theoretical and experimental basis of special relativity do not exist. 4. The Einstein's derivations on the formulas of transverse and longitudinal masses have a series of elementary mistakes in mathematics and physics. Einstein took the relative speed between two reference frames as the arbitrary moving velocity of a particle, and the obtained formulas were completely different from the existing mass-velocity of special relativity. 3. When Einstein derived the mass-energy relationship, he only calculated the work done by the force in the x-axis direction of particle’s motion, ignoring the work done by the force at the y- and z-axes directions. Meanwhile, the constant relative motion velocity between two reference frames was misused as the variable arbitrary velocity of a particle. Therefore, Einstein had not derived the mass-velocity formula and mass-energy relationship used in the present special relativity.

Chiral kinetic theory in the presence of dark photon

Finding signatures of dark matter in transport characteristics of solids would be an important step on the road to detect this illusive component of the mass of our Universe. This is especially important and timely as the experiments designed to directly detect dark matter particles continue to provide negative results. As a first step in this direction we consider topologically nontrivial Weyl or Dirac semimetals and derive the modified kinetic equation taking into account two coupled $U(1)$-gauge fields, one being the standard Maxwell electromagnetic field and other corresponding to the dark sector. The resulting Boltzmann kinetic equation is modified by the Berry curvature which couples to both visible and dark sector gauge fields. It was revealed that the dark sector induces modifications of transport coefficients due to the appearance of coupling constant between gauge fields and dark sector magnetic field.

Stable three-dimensional (un)charged AdS gravastars in gravity’s rainbow

In this work, we study the three-dimensional AdS gravitational vacuum stars (gravastars) in the context of gravity’s rainbow theory. Then we extend it by adding the Maxwell electromagnetic field. We compute the physical features of gravastars, such as proper length, energy, entropy, and junction conditions. Our results show that the physical parameters for charged and uncharged states depend significantly on rainbow functions. Besides from charged state, they also depend on the electric field. Finally, we explore the stability of thin shell of three-dimensional (un)charged AdS gravastars in gravity’s rainbow. We show that the structure of thin shell of these gravastars may be stable and is independent of the type of matter.

Dynamical chiral magnetic current and instability in Weyl semimetals

Weyl semimetals realize massless relativistic fermions with two Weyl nodes separated in energy and momentum space, whose low-energy physics is described by Dirac fermions with an axial gauge constant. Here, we study their electromagnetic linear responses based on the effective field theory and on the chiral kinetic theory. Although the static chiral magnetic effect is canceled by the Chern-Simons current under the Pauli-Villars regularization, a dynamical magnetic field is found capable of driving an electric current along its direction, with the total transported charge being independent of temperature and chemical potential for a uniform field. We also incorporate dissipation in the relaxation-time approximation and study collective excitations coupled with Maxwell electromagnetic fields when Weyl node populations deviate from equilibrium. Their dispersion relations at low frequency and long wavelength are determined only by electric, chiral magnetic, and anomalous Hall conductivities, which predict unstable modes leading to anisotropic generation of electromagnetic waves oriented to the direction of Weyl node separation.

Cogging Torque Minimization of PMBLDC Motor for Application in Battery Electric Vehicle

Since the beginning, researchers have focused globally on the automotive industry, which recently yielded a notable increase in the development of electric vehicles. The cogging torque of the motor is the leading cause of acoustic noise and vibration. Therefore, this paper aims to reduce the cogging torque of Brushless DC motors in electric vehicles. The power rating of the two-wheeler battery electric vehicle is determined with kinematic dynamic equations. The choice of material and the combination of pole slots impact the vehicle’s overall performance, particularly in raising the average torque of the motor. Finite element based Ansys Maxwell electromagnetic field simulation software has been used to design and analyze the electric and magnetic field parameters of BLDC motor using several rotor poles embrace factor values. The findings of this study are expected to reduce vibration and noise in electric vehicles with increased average torque.

The Completeness of Classical Electromagnetic Theory

The core of classical electromagnetic field theory is Maxwell electromagnetic field equations. Each of its formulas is supported by experimental facts, and its mathematical logic is rigorous and self-consistent, which has been tested for a long time in application.Therefore, its correctness is beyond doubt. In this paper, on the premise of affirming the great significance and important contribution of Maxwell equations(ME), the possible problems and solutions are discussed. Since ME and its derived wave equation (MWE) are vectorized partial differential equations, it is difficult to solve them strictly. In this paper, the solutions of vectorized ME and vectorized MWE are discussed in depth, and the necessity of Hansen function analysis is illustrated before the concrete calculation of engineering structures. Another method is to use vector partial differential operator theory to derive the standard basic equations expressed by state functions, and change the traditional calculation in Euclid space to the calculation in wave function space. Singularities and singularity are also avoided in the process. This paper argues that the completeness and modernity of traditional electromagnetic theory can only be improved by introducing the concept of particle, because the wave field processed by ME is actually a quantum field of light. The motion equation of electromagnetic field in classical theory is ME. In quantum theory, the field vector is an operator, governed by ME. The photon theory successfully explained the photoelectric effect in a way that ME could not. But in the mainstream theory, the photon rest mass is equal to zero, which blocks the way to add particle concept to ME. In 1936, Proca equations assumed ≠0, and with the support of quantum electrodynamics(QED), ME was improved. In this paper, the Proca equations are approved and the Proca wave equation (PWE) is further derived. In short, it reflects the adherence to the concept of wave-particle duality. The extended Maxwell equations proposed by Chinese scientist recently should be emphasized and discussed in this paper.

Research on vibration of the reactor for HVDC thyristor protection

As the key equipment to protect the thyristor of HVDC converter valve, the vibration problem of anode saturable reactor (ASR) is very prominent. Its long-term vibration will even cause the failure of the whole converter valve system. From the perspective of multi-physical field coupling, this paper establishes the solid model of ASR, considers the influence of Maxwell electro-magnetic field and magnetostrictive effect, numerically calculates the magnetic field and vibration of iron core, analyzes the contribution of two forces to vibration, and expounds the vibration phenomenon of iron core at different positions. In order to evaluate the effectiveness of the simulation, a single iron core vibration experiment is designed and compared with the single iron core simulation. This study can predict the vibration level of ASR core and provide theoretical basis and calculation method for vibration reduction in ASR design stage.

Knowledge Analysis of Charged Particle Motion in Uniform Electromagnetic Field Based on Maxwell Equation

Abstract We study the motion states of charged particles in a homogeneous electromagnetic field based on the Maxwell equations. The authors propose the charged particle properties analysis based on the Maxwell equation and electromagnetic field, first explain the Maxwell equation and electromagnetic field properties analysis, and then analyze the charged particles in the composite field (electric and magnetic field coexistence). List the important knowledge points about the motion of charged particles in an electric field, and determine the center of the circle where the charged particles move in a circular motion, simulate the motion of charged particles in a uniform orthogonal electromagnetic field, if at, the trajectory of the charged particle is a short-amplitude cycloid, if, the trajectory of the charged particle is a long cycloid, if. The realization of simulation is mainly based on theory to obtain phenomena, although it has extensive practical significance for confirmatory experiments, when inspiring and guiding students to carry out inquiry learning, physics teachers should still organically combine simulation experiments with traditional experimental teaching, teacher explanations, and student experiments in teaching design and teaching implementation, in order to cultivate students' independent inquiry ability and experimental innovation ability.

Extended phase space thermodynamics for dyonic black holes with a power Maxwell field

In this paper, we investigate the thermodynamics of dyonic black holes with the presence of power Maxwell electromagnetic field in the extended phase space, which regards the cosmological constant $\mathrm{\ensuremath{\Lambda}}$ as a thermodynamic variable. For a generic power Maxwell black hole with the electric charge and magnetic charge, the equation of state is given as the function of rescaled temperature $\stackrel{\texttildelow{}}{T}$ in terms of other rescaled variables ${\stackrel{\texttildelow{}}{r}}_{+}$, $\stackrel{\texttildelow{}}{q}$, and $\stackrel{\texttildelow{}}{h}$, where ${r}_{+}$ is the horizon radius, $q$ is the electric charge, and $h$ is the magnetic parameter. For some values of $\stackrel{\texttildelow{}}{q}$ and $\stackrel{\texttildelow{}}{h}$, the phase structure of the black hole is uniquely determined. Moreover, the peculiarity of multiple temperature with some parameter configurations results in complex phase structures. Focusing on the power Maxwell Lagrangian with $\mathcal{L}(s)={s}^{2}$, we obtain the corresponding phase diagrams in the $\stackrel{\texttildelow{}}{h}\text{\ensuremath{-}}\stackrel{\texttildelow{}}{q}$ plane where the critical line extends to $\stackrel{\texttildelow{}}{h}=+\ensuremath{\infty}$. Then, we analyze the black holes' phase structure and critical behavior and display phase transition curves with different $\stackrel{\texttildelow{}}{h}$ in the $\stackrel{\texttildelow{}}{q}\text{\ensuremath{-}}\stackrel{\texttildelow{}}{T}$ plane. We also examine thermal stabilities of these black holes.

Higher-Dimensional Regular Reissner–Nordström Black Holes Associated with Linear Electrodynamics

Following the interpretation of matter source that the energy-momentum tensor of anisotropic fluid can be dealt with effectively as the energy-momentum tensor of perfect fluid plus linear (Maxwell) electromagnetic field, we obtain the regular higher-dimensional Reissner–Nordström (Tangherlini–RN) solution by starting with the noncommutative geometry-inspired Schwarzschild solution. Using the boundary conditions that connect the noncommutative Schwarzschild solution in the interior of the charged perfect fluid sphere to the Tangherlini–RN solution in the exterior of the sphere, we find that the interior structure can be reflected by an exterior parameter, the charge-to-mass ratio. Moreover, we investigate the stability of the boundary under mass perturbation and indicate that the new interpretation imposes a rigid restriction upon the charge-to-mass ratio. This restriction, in turn, permits a stable noncommutative black hole only in the 4-dimensional spacetime.

Acoustic Simulation of the Electric Vehicle Motor

People pay more and more attention to NVH (N-noise, V-vibration, and H-harshness) characteristics of electric vehicles and motors. The vibration and noise of the electric vehicle motor is a complex multi physical field problem, related to electromagnetic, mechanical, structural and sound fields. In this paper, firstly, the Maxwell electromagnetic field analysis software is used to build the electromagnetic simulation model of PMSM(Permanent magnet synchronous motor) motor, and then the electromagnetic excitation is calculated. Then, the magnetic solid coupling analysis is carried out by using the Maxwell module and harmonic response module of ANSYS Workbench, and the harmonic response of the motor structure under the action of electromagnetic excitation is simulated. After the simulation of magnetic solid coupling is completed, the BEM(Boundary element method) simulation of the permanent magnet synchronous motor is carried out with the acoustic simulation software LMS Virtual Lab. The acoustic simulation of the permanent magnet synchronous motor shows that the sound pressure level at three measurement points have obvious peak value at 3700Hz, 4500Hz, 5400Hz and 6400Hz respectively. The acoustic simulation results lay the foundation for the vibration and noise reduction of the motor.

Can the power Maxwell nonlinear electrodynamics theory remove the singularity of electric field of point-like charges at their locations?

We introduce a variable power Maxwell nonlinear electrodynamics theory which can remove the singularity of electric field of point-like charges at their locations. One of the main problems of Maxwell's electromagnetic field theory is related to the existence of singularity for the electric field of point-like charges at their locations. In other words, the electric field of a point-like charge diverges at the charge location which leads to an infinite self-energy. In order to remove this singularity a few nonlinear electrodynamics (NED) theories have been introduced. The Born-Infeld (BI) NED theory is one of the most famous among them. However the power Maxwell (PM) NED cannot remove this singularity. In this paper, we show that the PM NED theory can remove this singularity, when the power of PM NED is less than .

Dynamic response and control of neuros based on electromagnetic field theory

The time-varying electric fields generated by continuously pumping and transmitting calcium, potassium and sodium ions in cells not only affect the discharge activity of neurons, but also induce time-varying magnetic fields to further regulate the fluctuation of ions. According to the Maxwell's electromagnetic field theory, time-varying electric field and magnetic field can stimulate each other in the electrophysiological environment inside and outside the cells to produce electromagnetic field. In order to explore the discharge rhythm transition of neurons under the influence of electromagnetic fields, a five-dimensional (5D) HR neuron model (EMFN model for short) is established by introducing magnetic flux variable and electric field variable into a three-dimensional (3D) Hindmarsh-Rose (HR) neuron model. Firstly, the equilibrium distribution and global bifurcation properties of EMFN model are analyzed by Matcont software, then the existence of subcritical Hopf bifurcation, hidden discharge, coexistence of periodic discharge and resting state are found and analyzed. Secondly, by using the tools of two-parameter and one-parameter bifurcation, ISI bifurcation and the maximum Lyapunov exponent for numerical simulation, the period-adding bifurcation with and without chaos, mixed mode discharge and coexistence mode discharge in the EMFN model are analyzed in detail. At the same time, the transition law of discharge rhythm with the influence of electric field and magnetic field intensity is revealed. Finally, the Washout controller is used to convert the subcritical Hopf bifurcation into supercritical Hopf bifurcation, so the topological structure of EMFN model near the bifurcation point is changed for eliminating the hidden discharge. The research results of this paper confirm that the novel neuron model has rich discharge rhythm, which will affect the information transmission and coding, and provide some ideas for improving the neuron models, revealing the influence of electromagnetic field on biological nervous system, and exploring the pathogenic mechanism of some neurological diseases.

Research on Magnetic Coupled Resonant Wireless Charging Technology Applied To Intelligent Patrol Robots

Magnetic coupled resonance wireless charging technology can realize high power and high efficiency energy transmission at medium distance, which is highly suitable for wireless charging of patrol robots. In this paper, a magnetic-coupled resonant wireless charging system applied in the patrol robot is designed and researched. The working principle of magnetic coupled resonant wireless charging technology is firstly introduced. Then, based on the theory of equivalent circuit modeling, the transmission efficiency and load power of the system are deduced. Moreover, the coil resonance frequency is calculated, and the coil field is analyzed by using Maxwell electromagnetic field software. Finally, the simulation software of Simplorer and Maxwell is used to verify the feasibility and efficiency of wireless charging technology.

Optical modulation of repaired damage site on fused silica produced by CO2 laser rapid ablation mitigation**Project supported by the National Natural Science Foundation of China (Grant Nos. 51775147 and 51705105), the Science Challenge Project of China (Grant No. TZ2016006-0503-01), the Young Elite Scientists Sponsorship Program by CAST (Grant No. 2018QNRC001), the China Postdoctoral Science Foundation funded project (Grant Nos. 2018T110288

CO2 laser rapid ablation mitigation (RAM) of fused silica has been used in high-power laser systems owing to its advantages of high efficiency, and ease of implementing batch and automated repairing. In order to study the effect of repaired morphology of RAM on laser modulation and to improve laser damage threshold of optics, an finite element method (FEM) mathematical model of 351 nm laser irradiating fused silica optics is developed based on Maxwell electromagnetic field equations, to explore the 3D near-field light intensity distribution inside optics with repaired site on its surface. The influences of the cone angle and the size of the repaired site on incident laser modulation are studied as well. The results have shown that for the repaired site with a cone angle of 73.3°, the light intensity distribution has obvious three-dimensional characteristics. The relative light intensity on z-section has a circularly distribution, and the radius of the annular intensification zone increases with the decrease of z. While the distribution of maximum relative light intensity on y-section is parabolical with the increase of y. As the cone angle of the repaired site decreases, the effect of the repaired surface on light modulation becomes stronger, leading to a weak resistance to laser damage. Moreover, the large size repaired site would also reduce the laser damage threshold. Therefore, a repaired site with a larger cone angle and smaller size is preferred in practical CO2 laser repairing of surface damage. This work will provide theoretical guidance for the design of repaired surface topography, as well as the improvement of RAM process.

Enhanced Ehlers transformation and the Majumdar-Papapetrou-NUT spacetime

The transformation which adds (or removes) NUT charge when it is applied to electrovacuum, axisymmetric and stationary space-times is studied. After analysing the Ehlers and the Reina-Treves transformations we propose a new one, more precise in the presence of the Maxwell electromagnetic field. The enhanced Ehlers transformation proposed turns out to act as a gravitomagnetic duality, analogously to the electromagnetic duality, but for gravity: it rotates the mass charge into the gravomagnetic (or NUT) charge. As an example the Kerr-Newman-NUT black hole is obtained with the help of this enhanced transformation. Moreover a new analytical exact solution is built adding the NUT charge to a double charged black hole, at equilibrium. It describes the non-extremal generalisation of the Majumdar-Papapetrou-NUT solution. From the near-horizon analysis, its microscopic entropy, according to the Kerr/CFT correspondence, is found and the second law of black hole thermodynamics is discussed.

Cosmological magnetic field and dark energy as two sides of the same coin

It has been recently argued [Phys. Rev. D 98, 045008 (2018)] that the de Sitter phase in cosmology might be naturally generated as a result of the dynamics of the topologically nontrivial sectors in a strongly coupled QCD-like gauge theory in the expanding Universe. It is known that the de Sitter phase is realized in the history of our Universe twice: The first occurrence is coined as inflation, while the second time (which is occurring now) is dubbed as dark energy (DE). The crucial element of the proposal is the presence of a nontrivial gauge holonomy which is the source of the vacuum energy leading to the de Sitter behavior. It has been also argued that the anomalous coupling of the system with the Standard Model particles leads to the reheating epoch in the case of the inflationary phase. A similar anomalous coupling of the system with the Maxwell electromagnetic field during the DE epoch generates the cosmological magnetic field. The intensity of the field is estimated on the level of ${10}^{\ensuremath{-}10}\text{ }\text{ }\mathrm{G}$, while the corresponding correlation length reaches the scale of the visible Universe.

Probing Palatini-type gravity theories through gravitational wave detections via quasinormal modes

The possibility of testing gravity theories with the help of gravitational wave detections has become an interesting arena of recent research. In this paper, we follow this direction by investigating the quasinormal modes (QNMs) of the axial perturbations for charged black holes in the Palatini-type theories of gravity, specifically (1) the Palatini f(R) gravity coupled with Born-Infeld nonlinear electrodynamics and (2) the Eddington-inspired-Born-Infeld gravity (EiBI) coupled with Maxwell electromagnetic fields. The coupled master equations describing perturbations of charged black holes in these theories are obtained with the tetrad formalism. By using the Wentzel-Kramers-Brillouin (WKB) method up to 6th order, we calculate the QNM frequencies of the EiBI charged black holes, the Einstein-Born-Infeld black holes, and the Born-Infeld charged black holes within the Palatini R+alpha R^2 gravity. The QNM spectra of these black holes would deviate from those of the Reissner-Nordström black hole. In addition, we study the QNMs in the eikonal limit and find that for the axial perturbations of the EiBI charged black holes, the link between the eikonal QNMs and the unstable null circular orbit around the black hole is violated.

Numerical analysis of influence of thermochemical model on hypersonic magnetohydrodynamic control

<sec> In hypersonic flow, extremely high temperature due to shock aerodynamic heating leads plasma flow to form. By adding energy and momentum to the plas-ma flow field through the magnetic field on aircraft, the control of plasma flow field around aircraft can be realized. This has a broad prospect of applications in hypersonic aerodynamic control, aerothermal protection, and plasma distribution adjustment. Very recently, chemical reaction model and thermodynamic model were suggested to study the hypersonic magnetohydrodynamic control. However, the influence of different models and surface catalytic efficiency on hypersonic magnetohydrodynamic control are rarely analyzed in depth. </sec><sec> In this study, a comparison of different chemical reaction models and the influence of surface catalytic efficiency are discussed. Three-dimensional (3D) nu-merical simulation method and program of extra magnetic field coupled with reentry plasma flow under the assumption of low magnetic Reynolds number are developed by solving 3D chemical non-equilibrium Navier-Stokes equations and Maxwell electromagnetic field governing equations. Based on this method, the influence of different gas component models, chemical reaction models, and surface catalytic efficiency on hypersonic magnetohydrodynamic control are analyzed. The results show that the conductivity of plasma, calculated by different gas component models and chemical reaction models, can be quite different from each other, thus can influence the accurate study on the structure of hypersonic magneto flow field as well as the aerothermal and aerodynamic characteristics. Based on the calculation conditions in this paper, the Park chemical model has advantages in the consistency and accuracy in numerical simulation. The magnetic thermal protection is greatly influenced by the surface catalytic efficiency and the correlation between the magnetic thermal protection and the surface catalytic efficiency is nonlinear and can be quite different in different region. As the surface catalytic efficiency increases, the influence of magnetic field on heat flux at stagnation point drops drastically, then increases slowly, which is a joint result of thermal conduction and chemical component diffusion. The influence of magnetic field on magnetohydrodynamic drag character is less affected by the surface catalytic efficiency. As the catalytic efficiency increases, the influence of magnetic field on magnetohydrodynamic drag character drops slowly. </sec>