Electromagnetic Laws Research Articles

A case study of the application of spectral analysis of very low frequency (VLF) dip angle measurements in Arigidi, Akoko area, southwestern Nigeria

Very low frequency electromagnetic (VLF-EM) fields caused by geologic bodies such as faults, fissures, and fractures have been modeled as resulting from simple subsurface geometric, electric conductors namely, lines, sheets, and tabular plates and their VLF-EM response computed using the Biot-Savart law of electromagnetism. The Fourier spectra of the VLF-EM fields of these geologic bodies were obtained as a sum of exponential functions which depend on the wave number (spatial frequency) and depth of burial of the bodies. The results of the spectral analysis of the VLF-EM fields have been applied to VLF measurements in a hydro-geologic context of fracture location and depth computation in a basement complex terrain of Arigidi in Akoko area of southwestern Ngieria. The profile EM data were acquired using the GEONICS EM-16 VLF receiver. The VLF measurements successfully located subsurface fractures in the direction of N60 W. Spectral depth inversion to basement on the profiles yielded results that vary between 19.6m at the shallower end and 35.7m at the deeper end in the area of study. The results confirm that the VLF-EM methods are a fast and relatively low-cost method of weathered layer evaluation in the basement terrain.

Practical electromagnetics: from biomedical sciences to wireless communication

Preface. 1. INTRODUCTION. 1.1 Electrical sources and fundamental quantities. 1.2 Static and dynamic fields. 1.3 Working with complex numbers and functions. 2. VECTORS AND FIELDS. 2.1 Working with vectors. 2.2 Coordinate systems. 2.3 Differentiation and integration of vectors. 2.4 Gradient of the scalar field and its applications. 2.5 Divergence of the vector field and its applications. 2.6 Curl of the vector field and its applications. 2.7 The divergence theorem. 2.8 Stokes' theorem. DELTA. 2.9 Other operations involving 2.10 Helmholtz theorem. 3. BASIC LAWS OF ELECTROMAGNETICS. 3.1 Maxwell's equations in large scale/integral form. 3.2 Maxwell's equations in point/differential form. 3.3 Constitutive relations. 3.4 Boundary conditions. 3.5 Lorentz force equation. 3.6 Poynting vector and power flow. 4. UNIFORM PLANE WAVES. 4.1 The wave equation and uniform plane wave solutions. 4.2 Plane electromagnetic waves in Lossy media. 4.3 Uniform plane wave incident normally on an interface. 4.4 Uniform plane wave incident obliquely on an interface. 5. TRANSMISSION LINES. 5.1 Transmission line equations. 5.2 Finite length transmission line. 5.3 Smith chart. 5.4 Transients on transmission lines. 6. MODIFIED MAXWELL'S EQUATIONS AND POTENTIAL FUNCTIONS. 6.1 Magnetic charge and current. 6.2 Magnetic vector and electric scalar potentials. 6.3 Electric vector and magnetic scalar potentials. 6.4 Construction of solution in rectangular coordinates. 6.5 Construction of solution in cylindrical coordinates. 6.6 Construction of solution in spherical coordinates. 7. SOURCE IN INFINITE SPACE. 7.1 Fields of an infinitesimal source. 7.2 Antenna parameters. 7.3 Linear antennas. 7.4 Antenna arrays. 7.5 Friis transmission formula and the radar range equation. 8. ELECTROSTATIC FIELDS. 8.1 Laws of electrostatic fields. 8.2 Gauss' law. 8.3 Poisson's and Laplace's equations. 8.4 Capacitors and energy storage. 8.5 Further applications of Poisson's and Laplace's equations. 9. MAGNETOSTATIC FIELDS. 9.1 Laws of magnetostatic fields. 9.2 Inductors and energy storage. 9.3 Magnetic materials. 9.4 Magnetic Circuits. 10. WAVEGUIDES AND CAVITY RESONATORS. 10. 1 Metallic rectangular waveguide. 10. 2 Metallic circular cylindrical waveguide. 10.3 Rectangular cavity resonators. 10.4 Circular cylindrical cavity resonators. 11. NUMERICAL TECHNIQUES. 11.1 Finite difference methods. 11.2 The method of moments. 11.3 Scattering of plane EM waves from an infinitely long cylinder. Appendix A. Mathematical formulas. Appendix B. Delta function and evaluation of fields in unbounded media. Appendix C. Bessel functions. Appendix D. Legendre functions. Appendix E. Characteristics of selected materials. Appendix F. Physical constants. Appendix G. Decibels and Neper. Appendix H. Nomenclature and characteristics of standard rectangular waveguides. SELECTED REFERENCE BOOKS . Index.

Carbon Nano Tube (CNT) multiplexers for multiple-valued computing

Novel two types of Carbon Nano Tube (CNT)-based multiplexers are introduced The first device is a solid-state transmission gate (t-gate) multiplexer that uses CNT as a channel in the Field Effect Transistors (FET) of both n-FET and p-FET types that are used. Because of its very small size, it has been shown that a CNT-based FET switches reliably using much less power than a silicon-based device, and thus the new device will consume less power than traditional t-gate multiplexer. The second new CNT device uses the fundamental Lorentz magnetic force from the basic laws of Electromagnetics as a switching mechanism between two conducting CNTs. The implementation of multiple-valued Galois logic using the new CNT devices is shown. Since a multiplexer is a fundamental logic block, the new devices can have a wide range of applications in a wide variety of nano circuits.

Basic Properties of the Generalized Scattering Matrix of Waveguide Transformers

This paper examines analytically the operator properties of the generalized scattering matrix of the H-(E-) plane waveguide transformer in an arbitrary shape. Four fundamental laws of electromagnetism are used to derive a new form of the generalized energy-conservation statement. The structure of spectrum of the generalized scattering matrix and the spectrum localization are established. A practical significance of the considered basic properties is illustrated by the example of matrix models of the waveguide bends. The obtained analytical results are useful for testing the correctness of numerical solutions, as well as for the mathematical justification of the methods based on modal analysis.

The superposition principle of waves not fulfilled under M W Evans' O(3) hypothesis

In 1992, M W Evans proposed a so-called O(3) symmetry of electromagnetic fields by adding a constant longitudinal ‘ghost field’ to the well-known transversal plane em waves. He considered this symmetry as a new law of electromagnetics. Later on, since 2002, this O(3) symmetry became the centre of his Generally Covariant Unified Field Theory which he recently renamed as ECE Theory. One of the best-checked laws of electrodynamics is the principle of linear superposition of electromagnetic waves, manifesting itself in interference phenomena. Its mathematical equivalent is the representation of electric and magnetic fields as vectors. By considering the superposition of two phase-shifted waves we show that the superposition principle is incompatible with M W Evans' O(3) hypothesis.

No Lorentz property of M W Evans' O(3)-symmetry law**A remark on a former paper [1] in this journal.

The paper (Evans 2000 Phys. Scr. 61 287–91) ‘On the nature of the B(3) field’ essentially refers to a hypothesis that was proposed in 1992 by M W Evans: Evans claimed that a so-called O(3)-symmetry of electromagnetic fields should exist due to an additional constant longitudinal ‘ghost field’ B(3) accompanying the well-known transversal plane em waves. Evans considered this symmetry, a fixed relation between the transversal and the longitudinal amplitudes of the wave, as a new law of electromagnetics. In the paper (Evans 2000) in this journal the authors claim ‘that the Maxwell–Heaviside theory is incomplete and limited’ and should be replaced with Evans' O(3)-theory the centre of which is Evans' O(3)-symmetry law. Later on, since 2002, this O(3)-symmetry became the centre of Evans' CGUFT which he recently renamed as ECE theory. A law of physics must be invariant under admissible coordinate transforms, namely under Lorentz transforms. A plane wave remains a plane wave also when seen from arbitrary other inertial systems. Therefore, Evans' O(3)-symmetry law should be valid in all inertial systems. To check the validity of Evans' O(3)-symmetry law in other inertial systems, we apply a longitudinal Lorentz transform to Evans' plane em wave (the ghost field included). As is well-known from SRT and recalled here the transversal amplitude decreases while the additional longitudinal field remains unchanged. Thus, Evans' O(3)-symmetry cannot be invariant under (longitudinal) Lorentz transforms: Evans' O(3)-symmetry is not a valid law of physics. Therefore it is impossible to draw any valid conclusions from that wrongO(3)-hypothesis. The paper (Evans 2000) has no scientific basis.

Differential Forms and Bi-Anisotropic Media

Differential-form formalism appears to be an ideal tool for electromagnetic analysis because it allows one to express the basic electromagnetic laws in a most compact and elegant form. However, equations involving bi-anisotropic media have practically never been studied in this formalism, which may be due to missing algebraic tools. Introducing multivector dyadic algebra, a useful toolbox is obtained with which one can formulate medium problems in compact form. Analysis of fields in some classes of media is briefly reviewed in this paper, showing that great simplification in the analysis can be attained through the differential-form formalism. For convenience, an appendix giving the notation and basic algebraic rules for multivectors and dyadics is added at the end of the article.

An intuitive electromagnetic approach to MIMO communication systems [Wireless Corner

The aim of this paper is to introduce MIMO propagation in a simple and intuitive way, which exalts the role of the laws of electromagnetism in the channel capacity of space-time communication systems. The approach takes advantage of mode expansions in waveguides and spherical-harmonics expansions in free space to clarify the physical limitations in the channel capacity of MIMO systems

Environmental Health, Third Edition

By Dade W. Moeller Cambridge, MA:Harvard University Press, 2005. 606 pp. ISBN: 0-674-01494-4, $65 cloth At least once a week, I need a brief account of an environmental health area that falls outside my specialty. At those times, I usually am more likely to find what I need in Moeller’s second edition (1997) than in any of my other reference books. This third edition maintains the strengths of the two earlier editions: brief and clear presentations and broad coverage of environmental health. This edition contains 20 chapters. It begins with an overview and traditional chapters on toxicology and epidemiology. These three are followed by reviews of water, air, and solid waste. About halfway through the 600-page book, the chapters begin to incorporate topics that some environmental health volumes do not cover, such as rodents and insects, food, injury control, environmental economics and law, risk assessment, standards and monitoring, energy, and disasters. A sizeable portion of this material is new or updated for this third edition. For example, you will find new or redone sections on indoor air quality, environmental justice, endangered species, multiple chemical sensitivities, electromagnetic radiation, disasters, and ergonomics. In other words, this book is environmental health in the broadest sense of the word: It is not just pollution control. At the end of each chapter, the author adds an interesting “general outlook” section that summarizes his views of the future. Two of the most useful chapters are those on electromagnetic radiation and environmental law. The former begins with a description of the electromagnetic spectrum and uses that as a springboard to differentiate among risks associated with different forms of radiation. The chapter briefly reviews highly amplified risks about automobile traffic radar and cell phones and about electromagnetic fields from overhead lines. It also presents useful sections about radon, medical and dental applications, and nuclear materials from electricity-generating stations and nuclear weapons testing. The overall goal is to help readers understand that not all radiation is to be equally dreaded and that some of the most feared radioactive elements are less dangerous than their less feared counterparts. The chapter on environmental law is helpful because the author tries hard to be comprehensive. Moeller offers lists of laws, brief comments on what the laws do and do not accomplish, the trajectory of laws during the last century, and their implementation. This is followed immediately by a chapter on environmental standards that is a good sequel to the law chapter. Every textbook has limitations. The most obvious is that it takes so long to write one that some of the material is bound to be out of date by the time the book is published. Hence, I would like to have seen more about globalization, pollution prevention, damages to natural resources, terrorism, and life-cycle costs than this edition offers. The author does not ignore these; they are mentioned here and there in the book, but not to the extent needed. If I have a problem with the book, it is the failure to present a separate chapter on risk perception. I realize that environmental scientists want to operate on the premise that decisions are made using rational thinking processes based on scientific evidence. Unfortunately, as a person who has been studying environmental policy for over 30 years, I say unequivocally that risk perception, trust, and mental models of risk have a major impact on environmental health policies. A chapter needs to be added that includes why people dread some hazards (nuclear weapons, terrorism, handguns) and so their risk is amplified, whereas other hazards are much more tolerable to the public and to elected officials (tobacco, alcohol). Despite this critique, I really like this book, I use it myself, and I will use it in my senior-level undergraduate environmental health course.

The Mathematical Basis for Physical Laws

Laws of mechanics, quantum mechanics, electromagnetism, gravitation and relativity are derived as “related mathematical identities” based solely on the existence of a joint probability distribution for the position and velocity of a particle moving on a Riemannian manifold. This probability formalism is necessary because continuous variables are not precisely observable. These demonstrations explain why these laws must have the forms previously discovered through experiment and empirical deduction. Indeed, the very existence of electric, magnetic and gravitational fields is predicted by these purely mathematical constructions. Furthermore these constructions incorporate gravitation into special relativity theory and provide corrected definitions for coordinate time and proper time. These constructions then provide new insight into the relationship between manifold geometry and gravitation and present an alternative to Einstein’s general relativity theory.

Modelling of Spool Position Feedback Servovalves

Based on a critical review of the previous research and the comprehensive theoretical analysis of all functional parts of two-stage electrohydraulic servovalves with a spool position feedback (a current amplifier, a torque motor, the first and the second stage of hydraulic amplification) a detailed mathematical model of the servovalves was created. The analysis was based on the fundamental laws of electromagnetism, fluid mechanics and general mechanics. The model parameters are physical quantities and the complexity of the model is only limited by the possibility of the correct numerical integration. It includes phenomena and quantities that are of influence on the behaviour of the servovalves, so it can predict their function in a wide range of expected working regimes. Results obtained with the numerical modelling on a personal computer were compared with the appropriate experimental data and the validity of the proposed model was confirmed with satisfactory accuracy.

Análisis de los procesos de aplicación de las Leyes de Gauss y Ampère por estudiantes universitarios de España y Argentina

El objetivo principal de este trabajo es analizar las formas de razonamiento que presentan los estudiantes universitarios en torno a dos de las leyes del electromagnetismo: la de Gauss (campo eléctrico) y la de Ampère (campo magnético). En ese sentido, hemos supuesto que los déficits observados en la comprensión y utilización de ambas leyes no son consecuencia, únicamente, de la existencia de preconcepciones o de ideas alternativas entre aquéllos sino también del uso habitual de razonamientos basados en la metodología de 'sentido común' que conduciría a razonamientos que determinados autores denominan de ''reducción funcional' y 'fijación funcional'. Para tratar de validar nuestra hipótesis hemos diseñado cinco situaciones problemáticas de tipo abierto con énfasis en las explicaciones. Los resultados obtenidos parecen confirmar que los estudiantes universitarios presentan serias dificultades de aprendizaje en lo que se refiere a las dos leyes analizadas.

A Local-Ether Wave Equation and the Consequent Electromagnetic Force Law

—The local-ether wave equation incorporating a nature frequency and the electric scalar potential is presented, from which the electrostatic force in conjunction with the inertial mass is derived. It is found that the inertial mass of a charged particle originates from the temporal variation of the associated matter wave. Further, the wave equation is extended by connecting the scalar potential to the augmentation operator which in turn is associated with the momentum operator and the velocity of source particles. From this local-ether wave equation, a first-order time evolution equation is derived, which in turn leads to the electromagnetic force law based on the augmented potentials. Under the low-speed condition, this law reduces to the modified Lorentz force law.

Wave Equations for Bi-Anisotropic Media in Differential Forms

Differential-form formalism appears to be an ideal tool for electromagnetic analysis because it allows one to express the basic electromagnetic laws in a most compact and elegant form. In fact, the Maxwell equations for the two electromagnetic two-forms are represented by two differential equations of first-order in the simplest possible form. Connection between the two-forms in a homogeneous and time-invariant linear medium is given by a simple algebraic equation. However, constructing the wave equation for a single electromagnetic two-form through elimination appears to be cumbersome and such an equation corresponding to the general bianisotropic medium could not be found in the literature. The present paper gives one possibility for its derivation based on operations in multivector and dyadic algebra. Two special media are considered in more detail leading to wave equations with scalar second-order and factorized fourth-order operators.

Magnetic diagnostics: General principles and the problem of reconstruction of plasma current and pressure profiles in toroidal systems

Restrictions on magnetic diagnostics are discussed. Being related to the integral nature of the measurable quantities, these follow from the fundamental laws of electromagnetism. A series of examples demonstrating the strength of these restrictions is analysed. The general rule is emphasized that information obtained from external magnetic measurements is insufficient for reliable evaluation of plasma current and pressure profiles in tokamaks and in stellarators. The underlying reason is that outside the plasma the self-field of the equilibrium plasma currents is determined by the boundary conditions on the plasma surface alone.

Gauge symmetryand gravito-electromagnetism

A tensor description of perturbative Einsteinian gravity about anarbitrary background spacetime is developed. By analogy with thecovariant laws of electromagnetism in spacetime, gravito-electromagnetic potentials and fields are definedto emulate electromagnetic gauge transformations undersubstitutions belonging to the gauge symmetry group ofperturbative gravitation. These definitions have the advantagethat on a flat background, with the aid of a covariantly constanttimelike vector field, a subset of the linearized gravitationalfield equations can be written in a form that is fully analogousto Maxwell's equations (without awkward factors of four andextraneous tensor fields). It is shown how the remainingequations in the perturbed gravitational system restrict the timedependence of solutions to these equations and thereby prohibitthe existence of propagating vector fields. The induced gravito-electromagnetic Lorentz force on a test particle is evaluated interms ofthese fields together with the torque on a small gyroscope. It isconcluded that the analogy of perturbative gravity to Maxwell'sdescription of electromagnetism can be valuable for(quasi-)stationary gravitational phenomena but that the analogyhas its limitations.

On a fundamental physical principle underlying the point location algorithm in computer graphics [for EM field theory

The issue of point location is an important problem in computer graphics and the study of efficient data structures and fast algorithms is an important research area for both computer graphics and computational geometry disciplines. When filling the interior region of a planar polygon in computer graphics, it is necessary to identify all points that lie within the interior region and those that are outside. Sutherland and Hodgman are credited for designing the first algorithm to solve the problem. Their approach utilizes vector construction and vector cross products, and forms the basis of the "odd parity" rule. To verify whether a test point is within or outside a given planar polygon, a ray from the test point is drawn extending to infinity in any direction without intersecting a vertex. If the ray intersects the polygon outline an odd number of times, the region is considered interior. Otherwise, the point is outside the region. In three-dimensional space (3-space), Lee and Preparata propose an algorithm but their approach is limited to point location relative to convex polyhedrons with vertices in 3-space. Although it is rich on optimal data structures to reduce the storage requirement and efficient algorithms for fast execution, a proof of correctness of the algorithm, applied to the general problem of point location relative to any arbitrary surface in 3-space, is absent in the literature. This paper argues that the electromagnetic field theory and Gauss's Law constitute a fundamental basis for the "odd parity" rule and shows that the "odd parity" rule may be correctly extended to point location relative to any arbitrary closed surface in 3-space.

An approach to improve the synchronous machine model in saturated state

A magnetic study has been linked to an electrical survey to improve a saturated synchronous machine model. The machine is supplied by a sinusoidal voltage source, but the developed model could be extended to a non‐sinusoidal case. The last one corresponds to electrical machines supplied by power electronic converters. First, the machine magnetic state is analysed from a numerical calculation based on the finite element method. Saturation laws are established. The results show that some parameters which were considered constant values vary with the saturation level. Second, we introduce the saturation laws in the machine electrical equations. The voltage supplied machine is simulated for an electrical transient state. Finally, the developed model is compared to a reference one which uses experimental constant parameters. The simulation results show that the proposed electromagnetic laws significantly modify the machine currents’ waveforms.

Half the electron

J.J. Thomson discovered the electron a hundred years ago, but he never quite accepted that the electron does not obey the classical laws of electromagnetism that he used for discovering it. This article discusses the experiments made by Thomson to measure the charge of the electron and the charge per unit mass. The interpretation by Thomson of the experimental results is outlined including the electron's role in the atom and other speculations.

Unification of Electromagnetic Laws and Rules

With Lorentz force as the basic postulate, flux-current interaction and flux-cutting induction are interpreted as, respectively, electromotively moving charges experiencing a mechanical force, and mechanically moving charges experiencing an electromotive force, across a magnetic field. This elegantly symmetrical unification leads to all rules of electromagnetism becoming universally right handed.