Electromagnetic Transformation Research Articles

Singular gauge transformations in geometrodynamics

The new tetrads introduced previously for non-null electromagnetic fields in Einstein–Maxwell spacetimes enable a direct link to the local electromagnetic gauge group of transformations. Due to the peculiar elements in the construction of these new tetrads, a direct connection can be established between the local group of electromagnetic gauge transformations and local groups of tetrad transformations on two different local and orthogonal planes of eigenvectors of the Einstein–Maxwell stress–energy tensor. These tetrad vectors are gauge dependent. It is an interesting and relevant problem to study if there are local gauge transformations that can map on the timelike-spacelike plane, the timelike and the spacelike vectors into the intersection of the local light cone and the plane itself. How many of these local gauge transformations exist and how the mathematics and the geometry of these particular transformations play out. These local gauge transformations would be singular and it is important to identify them.

Full spacetime inversion generated by electromagnetic Abelian gauge transformations

Full spacetime inversion generated by electromagnetic Abelian gauge transformations

Electromagnetic wave transformation in an oscillator medium with growing density.

The model of a medium made of oscillators can describe various materials, including artificial ones made of meta-atoms. Here the transformation of an electromagnetic wave in such a medium with rapidly growing oscillator density is studied. The initial polariton is shown to be transformed not only into new polariton modes but also into natural oscillations of the existing and created oscillators. The oscillations produce zero net polarization but consume significant amount of the initial polariton energy. Although the boundary conditions at the temporal jump are sufficient to find the new polaritons, the description of the polarization oscillations requires integrating the material equations because the oscillations are uncoupled from the fields. Under some conditions, the spatial dependence of the amplitude of the oscillations can provide a snapshot of the electromagnetic field distribution at the moment of rapid density growth. Some subtle issues related to the continuity conditions at the density jump are also discussed.

Electromagnetic Field Transformation from a Surface Closed Around the Antenna to its Aperture

Electromagnetic Field Transformation from a Surface Closed Around the Antenna to its Aperture

Multi-cloak invisibility, a new strategy for simultaneous acoustic and electromagnetic invisibility

Based on electromagnetic and acoustic transformation theory, a new strategy has been presented in this article to implement double invisibility cloaking, which has not been done yet. By applying a combination of four conventional cloaking methods, for cloaking an object by electromagnetic and acoustic waves, which are two essential methods for objects detection (sonar, radar, eye, ear, camera …), the object will be blind or deaf, while it will be undetectable acoustically and electromagnetically simultaneously. In deaf mode structure, the object has an interaction with electromagnetic waves; so it can see what is outside the cloaking structure electromagnetically while it has not any acoustic interaction with the outside, but in blind mode arrangement, as opposed to the deaf arrangement, the acoustic link has turned on while there is no electromagnetic connection. Finally, the proposed approach in this paper does not generalize for any two classes of physics, electrical-mechanical, thermal-mechanical, electrical-thermal, electromagnetic-sonic, etc.

Electromagnetic field transformation from a surface closed around the antenna to its aperture

The article proposes a direct algorithm for reconstruction the electromagnetic field at the antenna aperture, which can be used to solve problems of diagnostics and spatial filtering. The algorithm is based on the solution of Maxwell's equations in the form of advanced potentials of the electromagnetic field. It is shown that following from it advanced electromagnetic waves are equivalent to retarded electromagnetic waves when the parameters of the medium are stationary and linear. The direct algorithm is formulated as the multiplication of the transformation operator matrix by the known vector of the electromagnetic field on a closed surface. In this case, the transformation outward (far field) or inward (aperture) of the surface is described by the same operator and differs only in the signs of the input quantities. Unlike the known ones, the direct algorithm does not require scanning the electromagnetic field on canonical surfaces or solving a large system of integral equations. This makes it optimal for use in new near-field measurement systems based on industrial robots, unmanned aerial vehicles, etc. Verification of the developed algorithm using experimental data has shown the possibility of reconstruction the normalized distribution of the electric field strength at the antenna aperture with an error less than 2 dB.

Study of the Magnetoelastic Properties of the Fe73.7Cu1.0Nb3.2Si12.7B9.4 Amorphous-Crystalline Alloy and Experimental Technique by Use of Electromagnetic Acoustic Transformation

Study of the Magnetoelastic Properties of the Fe73.7Cu1.0Nb3.2Si12.7B9.4 Amorphous-Crystalline Alloy and Experimental Technique by Use of Electromagnetic Acoustic Transformation

A plasmonic lens based on coordinate transformation

With the development and maturity of nanofabrication technology, many nanostructures with specific electromagnetic characteristics and optical functions have been designed and demonstrated. Artificial materials with these special optical properties are known as metamaterials. In this paper, a metamaterial lens is proposed and characterized. After using the space transformation approach based on the coordinate transformation principles, the lens becomes anisotropic and inhomogeneous, thus realizing the regulation of electromagnetic waves. The electromagnetic wave transformation characteristics of the superlens are numerically analysed by irradiating a plane transverse wave with a wavelength of 300 nm onto a rectangular slab. The results show that the waveform of the incident light changes from plane waves to cylindrical after passing through the superlens. The validity of the superlens is verified by finite element method calculations.

A Theoretical Derivation of Faraday's Second Law of Electromagnetic Induction

Fraday's law of induction is one of the most important laws in electromagnetism. In this paper, based on the curl of electric field vector generated from a moving charge, we show a detailed derivation process, which describes how to derive the rate of change of the magnetic field with time from the curl of the electric field vector. From the mathematical derivation, we found that the acceleration of the charge movement can generate one electric field, which is essentially equivalent to the a non-conservative electric field excited by the ratio of change of magnetic field with time. The theoretical derivation is meaningful to explore the nature of electromagnetic field transformation.

Encoding electromagnetic transformation laws for dimensional reduction

AbstractElectromagnetic phenomena are mathematically described by solutions of boundary value problems. For exploiting symmetries of these boundary value problems in a way that is offered by techniques of dimensional reduction, it needs to be justified that the derivative in symmetry direction is constant or even vanishing. A generalized notion of symmetry can be defined with different directions at every point in space, as long as it is possible to exhibit unidirectional symmetry in some coordinate representation. This can be achieved, for example, when the symmetry direction is given by the direct construction out of a unidirectional symmetry via a coordinate transformation which poses a demand on the boundary value problem. Coordinate independent formulations of boundary value problems do exist but turning that theory into practice demands a pedantic process of backtranslation to the computational notions. This becomes even more challenging when multiple chained transformations are necessary for propagating a symmetry. We try to fill this gap and present the more general, isolated problems of that translation. Within this contribution, the partial derivative and the corresponding chain rule for multivariate calculus are investigated with respect to their encodability in computational terms. We target the layer above univariate calculus, but below tensor calculus.

Dynamical symmetry breaking in Abelian geometrodynamics

A new tetrad is introduced within the framework of geometrodynamics for non-null electromagnetic fields. This tetrad diagonalizes the Einstein-Maxwell stress-energy tensor, any stress-energy tensor in a local and covariant way, and allows for maximum simplification of the expression of the electromagnetic field, in any curved four-dimensional Lorentzian spacetime, allowing for the identification of its degrees of freedom in two local scalars. New isomorphisms are proved. A new internal-spacetime mapping is established using these new tetrads. It is possible to map the local group of electromagnetic gauge transformations into the transformation groups of tetrad vectors on two local orthogonal planes. The planes that diagonalize the stress-energy tensor. We will discuss through a first order perturbative formulation the local loss of symmetry when a source of electromagnetic and gravitational field interacts with an agent that perturbs the original geometry associated to the source. The loss of symmetry will be manifested by the tilting of these planes under the influence of an external agent. In this strict sense the original local symmetry will be lost, however a new symmetry will arise. The purpose of this report is to show that the geometrical manifestation of local gauge symmetries is dynamic.

New symmetry for the imperfect fluid

We will address the existence of a new symmetry for an imperfect fluid by introducing local four-velocity gauge-like transformations for the case when there is vorticity. A similar tetrad formulation as to the Einstein–Maxwell spacetimes formalism presented in previous manuscripts will be developed in this manuscript for the imperfect fluids. The four-velocity curl and the metric tensor will be invariant under these kind of four-velocity gauge-like local transformations. While the Einstein–Maxwell stress-energy tensor is locally gauge invariant under electromagnetic gauge transformations, the perfect fluid stress-energy tensor will not be invariant under four-velocity gauge-like local transformations. We will dedicate our analysis to the imperfect fluid stress-energy tensor that will be invariant under local four-velocity gauge-like transformations when additional transformations are introduced for several variables included in the stress-energy tensor itself. We will also pay special attention to the construction of a vorticity stress-energy tensor invariant under local four-velocity gauge-like transformations. An application on neutron stars will be developed in order to show the simplifications brought about by these new tetrads.

Signature-causality reflection generated by Abelian gauge transformations

In this paper, we want to better understand the causality reflection that arises under a subset of Abelian local gauge transformations in geometrodynamics. We proved in previous papers that in Einstein–Maxwell spacetimes, there exist two local orthogonal planes of gauge symmetry at every spacetime point for non-null electromagnetic fields. Every vector in these planes is an eigenvector of the Einstein–Maxwell stress–energy tensor. The vectors that span these local orthogonal planes are dependent on electromagnetic gauge. The local group of Abelian electromagnetic gauge transformations has been proved isomorphic to the local groups of tetrad transformations in these planes. We called LB1 the local group of tetrad transformations made up of SO(1, 1) plus two different kinds of discrete transformations. One of the discrete transformations is the full inversion two by two which is a Lorentz transformation. The other discrete transformation is given by a matrix with zeroes on the diagonal and ones off-diagonal two by two, a reflection. The group LB1 is realized on this plane, we call this plane one, and is spanned by the time-like and one space-like vectors. The other local orthogonal plane is plane two and the local group of tetrad transformations, we call this LB2, which is just SO(2). The local group of Abelian electromagnetic gauge transformations is isomorphic to both LB1 and LB2, independently. It has already been proved that a subset of local electromagnetic gauge transformations that leave the electromagnetic tensor invariant induces a change in sign in the norm of the tetrad vectors that span the local plane one. The reason is that one of the discrete transformations on the local plane one that belongs to the group LB1 is not a Lorentz transformation, it is a flip or reflection. It is precisely on this kind of discrete transformation that we have an interest since it has the effect of changing the signature and the causality. This effect has never been noticed before.

Measuring system for comprehensive testing of electrical machines

The article presents a measuring system designed for a comprehensive experimental testing of various types of electric machines. These tests include measurements of electrical, electromagnetic, kinematic, as well as mechanical and thermal quantities. The basic measurements of electrical machines include currents and voltages in electrical circuits, including voltages on resistive and generally impedance elements of these circuits, and induced voltages. Depending on the machine class and type, the measured values are constant or change over time. Some magnitudes of electromagnetic transformations are measured in the area of machine construction. In addition, the parameters of the measured values of the type of signal discriminants (average, effective and maximum values) and their waveforms are presented. Due to the wide range of machine state parameters, i.e. its state variables - in different load states, the multiplicity of these signals and the need to know their different characteristics, it becomes necessary to use individually adopted signal processing subsystems, i.e. signal acquisition systems, in the measuring systems. It is now possible thanks to the development in the CAM (Computer Aided Measurement) programming, for example using the graphical programming language of the integrated LabVIEW system. The article also presents examples of subsystems for the acquisition of measurements of nonelectromagnetic signals like vibrational and acoustic ones generated in machines. Keywords: electric machines, measurements, measuring system

Overview of Power Management for Triboelectric Nanogenerators

Triboelectric nanogenerators (TENGs) have demonstrated enormous potential applications for acquiring human motion energy and ambient mechanical energy, which is the foundation of energy for the new era. However, with alternating current (AC) pulse and huge inherent impedance, the TENGs usually exhibit low‐energy supply efficiency when either powering conventional electronics or charging energy storage devices directly. Efficient power management has always been a technical bottleneck for the TENGs toward practical applications in self‐powered microsystems. Over the past years, several strategies of power management have been proposed, such as rectification, electromagnetic transformation, capacitive transformation, and direct current (DC) conversion, which can be used for voltage regulation, impedance matching, and efficiency improvement for electronics. Herein, the recent advances on power management for TENGs are systematically reviewed and analyzed, which has exhibited manageable triboelectric power by electronics as an important research issue of TENGs. Finally, the existing challenges and future perspectives in this field are discussed.

Measurement of Residual Stresses of Locomotive Wheel Treads During the Manufacturing Technological Cycle

Abstract The production of two-wheeled rolling stock represents, at first glance, a simple assembly process that significantly affects the overall functionality and safety of the vehicle. This is due to residual stresses that arise after assembly by pressing the wheel on the axle. The state of stress after assembly remains in the design has a decisive influence on the load-bearing capacity of the two-wheel drive, its lifespan but also the transfer of the pulling force in the case of locomotives. Therefore, it is very important to find suitable methods for determining residual stresses. Numerical and experimental approaches are already in place to gain information on the state of stress after compression, or during a real operation. The developed techniques and tools for estimation of residual stresses in locomotive wheel treads based on the acoustoelasticity effect using electromagnetic acoustic transformation are described in the paper. The original results of residual stress measurement in the treads during a technological cycle of locomotive wheel pair manufacturing are presented.

What Are Observables in Hamiltonian Einstein–Maxwell Theory?

Is change missing in Hamiltonian Einstein-Maxwell theory? Given the most common definition of observables (having weakly vanishing Poisson bracket with each first-class constraint), observables are constants of the motion and nonlocal. Unfortunately this definition also implies that the observables for massive electromagnetism with gauge freedom (Stueckelberg) are inequivalent to those of massive electromagnetism without gauge freedom (Proca). The alternative Pons-Salisbury-Sundermeyer definition of observables, aiming for Hamiltonian-Lagrangian equivalence, uses the gauge generator G, a tuned sum of first-class constraints, rather than each first-class constraint separately, and implies equivalent observables for equivalent massive electromagnetisms. For General Relativity, G generates 4-dimensional Lie derivatives for solutions. The Lie derivative compares different space-time points with the same coordinate value in different coordinate systems, like 1 a.m. summer time vs. 1 a.m. standard time, so a vanishing Lie derivative implies constancy rather than covariance. Requiring equivalent observables for equivalent formulations of massive gravity confirms that G must generate the 4-dimensional Lie derivative (not 0) for observables. These separate results indicate that observables are invariant under internal gauge symmetries but covariant under external gauge symmetries, but can this bifurcated definition work for mixed theories such as Einstein-Maxwell theory? Pons, Salisbury and Shepley have studied G for Einstein-Yang-Mills. For Einstein-Maxwell, both the electromagnetic field strength F and the metric g are invariant under electromagnetic gauge transformations and covariant (changing by a Lie derivative) under 4-dimensional coordinate transformations. Using the bifurcated definition, these quantities count as observables, as one would expect on non-Hamiltonian grounds.

What Are Observables in Hamiltonian Einstein\u2013Maxwell Theory?

Is change missing in Hamiltonian Einstein–Maxwell theory? Given the most common definition of observables (having weakly vanishing Poisson bracket with each first-class constraint), observables are constants of the motion and nonlocal. Unfortunately this definition also implies that the observables for massive electromagnetism with gauge freedom (‘Stueckelberg’) are inequivalent to those of massive electromagnetism without gauge freedom (‘Proca’). The alternative Pons–Salisbury–Sundermeyer definition of observables, aiming for Hamiltonian–Lagrangian equivalence, uses the gauge generator G, a tuned sum of first-class constraints, rather than each first-class constraint separately, and implies equivalent observables for equivalent massive electromagnetisms. For General Relativity, G generates 4-dimensional Lie derivatives for solutions. The Lie derivative compares different space-time points with the same coordinate value in different coordinate systems, like 1 a.m. summer time versus 1 a.m. standard time, so a vanishing Lie derivative implies constancy rather than covariance. Requiring equivalent observables for equivalent formulations of massive gravity confirms that G must generate the 4-dimensional Lie derivative (not 0) for observables. These separate results indicate that observables are invariant under internal gauge symmetries but covariant under external gauge symmetries, but can this bifurcated definition work for mixed theories such as Einstein–Maxwell theory? Pons, Salisbury and Shepley have studied G for Einstein–Yang–Mills. For Einstein–Maxwell, both F_{mu nu } and g_{mu nu } are invariant under electromagnetic gauge transformations and covariant (changing by a Lie derivative) under 4-dimensional coordinate transformations. Using the bifurcated definition, these quantities count as observables, as one would expect on non-Hamiltonian grounds.

Discussion the causes of electromagnetic field transformation in different frame of reference

The electromagnetic field; Frame of reference. Transformation; The theory of relativity

Adaptive Processing at Multiple Frequencies Using the Same Antenna Array Consisting of Dissimilar Nonuniformly Spaced Elements Over an Imperfectly Conducting Ground

In this communication, an adaptive processing is carried out simultaneously at multiple frequencies using the same antenna array consisting of nonuniformly spaced dissimilar antenna elements. The antenna array may not be deployed in free space but may be located over an imperfect ground plane. First, to correct the various electromagnetic effects affecting the array performance, an electromagnetic transformation technique is described that can compensate for the various coupling effects in the nonplanar array consisting of nonuniformly spaced dissimilar antenna elements operating over an imperfect ground. Then, a direct data domain least-squares method is used to extract the signal of interest in the presence of fluctuating jammer and clutter simultaneously at multiple frequencies, using a single snap shot of the data. In this procedure, there is no need to have any information about noise or clutter, whatsoever.