Electric Circuit Theory Research Articles

<italic>Q</italic> Controllable Antenna as a Potential Means for Wide-Area Sensing and Communication in Wireless Charging via Coupled Magnetic Resonances

Recently, wireless charging via coupled magnetic resonances gains attention because it has a potential of efficient mid-range wireless charging. Here, functions such as sensing at the transmitter and wireless communication from the target are the essential elements to realize the standard wireless charging system. Currently, the sensing and communication protocol of hardware (i.e., high-frequency power source and antenna configuration) compatible with wireless charging is gaining attention in terms of cost and space reduction due to the use of common components in multiple functions. However, these protocols have the problem of narrow effective areas. Therefore, this paper presents a method for wide-area sensing and communication with slight modification of the configuration. The basic concept is to expand the effective area related to antenna Q factor by using the Q controllable antenna acting as though the Q factor increased. The underlying theory was described with electric circuit theory. The experimental results showed that the Q factor can be increased until the resonance collapses, and the increase of Q factor has the potential to widen the effective area of sensing and communication.

THE PHASE REACTOR INDUCTANCE SELECTION TECHNIQUE FOR POWER ACTIVE FILTER

Purpose. The goal is to develop technique of the phase inductance power reactors selection for parallel active filter based on the account both low-frequency and high-frequency components of the electromagnetic processes in a power circuit. Methodology. We have applied concepts of the electrical circuits theory, vector analysis, mathematical simulation in Matlab package. Results. We have developed a new technique of the phase reactors inductance selection for parallel power active filter. It allows us to obtain the smallest possible value of THD network current. Originality. We have increased accuracy of methods of the phase reactor inductance selection for power active filter. Practical value. The proposed technique can be used in the design and manufacture of the active power filter for real objects of energy supply.

THREE-PHASE ENERGY SUPPLY SYSTEMS SIMULATION FOR THE TOTAL POWER LOSSES COMPONENTS ASSESSMENT

Purpose. The goal is to optimize a structure of Matlab-model of the three-phase energy supply system with power active filter. The mathematical model that describes the energy supply system modes of operation which contains additional losses is proposed. Methodology. We have applied concepts of the electrical circuits theory, mathematical modeling elements based on linear algebra and vector calculus, mathematical simulation in Matlab package. Results. We have developed two models of three-phase energy supply system. The first one is based on a vector representation, and the second one on the matrix representation of energy processes. Using these models we have solved the problem of maintaining unchanged the average useful power for 279 cases of energy supply system modes of operation. Originality. We have developed methods of mathematical analysis of a three-phase energy supply systems with polyharmonic voltages and currents in the symmetric and asymmetric modes. Practical value. We have created Matlab-model of a three-phase energy supply system with automated calculation of a correction factor. It allows reducing more than one order the time for energy processes elucidation in multiphase systems.

Shot noise in radiobiological systems

As a model for human tissue, this report considers the rate of free radical generation in a dilute solution of water in which a beta-emitting radionuclide is uniformly dispersed. Each decay dissipates a discrete quantity of energy, creating a large number of free radicals in a short time within a small volume determined by the beta particle range. Representing the instantaneous dissipated power as a train of randomly-spaced pulses, the time-averaged dissipated power p¯ and rate of free radical generation g¯ are derived. The analogous result in the theory of electrical circuits is known as the shot noise theorem. The reference dose of X-rays Dref producing an identical rate of free radical generation and level of oxidative stress is shown a) to increase with the square root of the absorbed dose, D, and b) to be far larger than D. This finding may have important consequences for public health in cases where the level of shot noise exceeds some noise floor corresponding to equilibrium biological processes. An estimate of this noise floor is made using the example of potassium-40, a beta-emitting radioisotope universally present in living tissue.

IMPLEMENTATION MODEL OF MOTOR TRACTION FORCE OF MAGLEV TRAIN

Purpose. Traction force implementation (TFI) by the motor of magnetic levitation train (MLT) occurs in the process of electric-to-kinetic energy transformation at interaction of inductor and armature magnetic fields. Ac-cordingly, the aim of this study is to obtain a correct description of such energy transformation. Methodology. At the present stage, a mathematical and, in particular, computer simulation is the main and most universal tool for analysis and synthesis of processes and systems. At the same time, radical advantages of this tool make the precision of selection of a particular research methodology even more important. It is especially important for such a large and complex system as MLT. Therefore the special attention in the work is given to the rationale for choosing the research paradigm selective features. Findings. The analysis results of existing TFI process model versions indicate that each of them has both advantages and disadvantages. Therefore, one of the main results of this study was the creation of a mathematical model for such process that would preserve the advantages of previous versions, but would be free from their disadvantages. The work provides rationale for application (for the purposes of research of train motor TFI) of the integrative holistic paradigm, which assimilates the advantages of the theory of electric circuit and magnetic field. Originality. The priority of creation of such paradigm and corresponding version of FI model constitute the originality of the research. Practical value. The main manifestation of practical value of this research in the opportunity, in case of use of its results, for significant increase in efficiency of MLT dynamic studies, on the condition that their generalized costs will not rise.

Use of virtual industry and laboratory machines to teach electric circuit theory

At the beginning of Fall 2012, the new modules of the Electrical Engineering Department at the Federal University of Ceara, Technology Center, Brazil, significantly modified the instructional philosophy of the TH0 176 Electric Circuit II module. The theory course was enhanced by the introduction of more engineering designs into the curriculum, adopting the virtual industry, and laboratory machine as a methodology to teach alternating electric circuit. This paper discusses the use of this new methodology in detailed form. An example is discussed, along with mathematical models, which describes electric circuit behavior, and it helps each team of students to have a specific homework. The approach presented in this paper can be adapted to any other course in engineering/science that involves mathematical calculations. So far, the course evaluations suggest that the students are more motivated and excited about electrical engineering as a career.

Implementation of power transformer controlled switching algorithm

Purpose – The paper presents two new algorithms of controlled switching the power transformer. The purpose of this paper is to obtain formulas that determine the moments of closing of the circuit breaker poles. The study contains projects of control systems for both algorithms. Design/methodology/approach – Mathematical formulas for the time instants of the breaker poles closing were developed on the basis of electric circuit theory and magnetic circuit theory. The presented systems were simulated using a model created in the Alternative Transients Program/Electromagnetic Transients Program software. Findings – Numerical simulations have proved that the shown systems properly perform the controlled switching carried out in accordance with the proposed algorithms. The times of the poles closing were correctly determined and the inrush currents were reduced to a level of the current of unloaded transformer. Originality/value – The results achieved are better than those shown in the literature. The solutions presented in the literature provide a reduction of inrush current to a value comparable to the rated current of the transformer, which is ten times greater than the no-load current. Additional achievement of the work is the development of analytical formulas that determine the times of the breaker poles closing.

Teaching and Learning of Fundamental Concepts of Ground Water Flow by a Specific Educational Software

Abstract The educational software FATSIM-A has been developed to simulate transient, non-lineal, conjugate problems of fluid flow and solute transport in porous media. Characteristics of the commercial codes, such as communications with the user in a pleasant windows environment, selection of the mesh grid, capabilities of advanced programming, etc. are installed in the software. The resulting simulation data (concentration and stream function isolines), including animations, are graphically shown in the environment of FATSIM-A itself or using MATLAB, due to suitable routines implemented in the software. The program can be used as a low cost laboratory educational tool for teaching groundwater flow with solute transport processes, such as saline intrusion, salt lake and salt dome problems. The program allows the user the information of the text file Spice code, whose structure and design rules can be easily accessed by graduate and under-graduate students with a basic knowledge of electrical circuit theory. Models designed by FATSIM-A of several sceneries implemented by students were explained to check the understanding of the problem.

New analytical methodologies for radiative heat transfer in enclosures based on matrix formalism and network analogy

This study proposes new matrix relationships of the radiative interactions in enclosures along with their corresponding applications. By means of several transformations one establishes matrix formulae based on equations of radiative exchanges containing variables defined in a discrete analog form, and further on, by means of a multidisciplinary approach, the solutions are organized in algorithms that use the theory of networks, graphs and electric circuits. The theoretical advancements consist in two different paths: the matrix formalism method (MFM) and the network analogy method (NAM). As a result of the advancements, a high degree of parameterization of the problem of radiative transfer in an enclosure is achieved and it facilitates superior physical interpretations at the level of the ensemble. It will be simple to use the developed methodologies in designs, balances and simulations.The conceived analytical methods are valuable, compact instruments for performing accurate radiative design for various technical systems: buildings, furnaces, solar collectors, etc.A mathematical formula det(F−I)=0 that is a consequence of the closed shape property of the enclosures is put forth for the first time. The inverse problem that may rise from the proposed boundary conditions is considered and solved. A validation of the analytical instruments provided by MFM and NAM is performed by using the Ansys Fluent tool that confirmed the results in margins less than 5%.The importance of the study resides in its applicability in diverse disciplines. In addition to the theoretical advancements, a comprehensive example is provided.

Transience and Recurrence of Random Walks on Percolation Clusters in an Ultrametric Space

We study transience and recurrence of simple random walks on percolation clusters in the hierarchical group of order N, which is an ultrametric space. The connection probability on the hierarchical group for two points separated by distance k is of the form \(c_k/N^{k(1+\delta )}, \delta >0\), with \(c_k=C_0+C_1\log k+C_2k^\alpha \), non-negative constants \(C_0, C_1, C_2\), and \(\alpha >0\). Percolation occurs for \(\delta 0\) and sufficiently large \(C_2\). We show that in the case \(\delta 0,\alpha >0\) there exists a critical \(\alpha _\mathrm{c}\in (0,\infty )\) such that the walk is recurrent for \(\alpha \alpha _\mathrm{c}\). The proofs involve ultrametric random graphs, graph diameters, path lengths, and electric circuit theory. Some comparisons are made with behaviours of simple random walks on long-range percolation clusters in the one-dimensional Euclidean lattice.

COMPONENTS OF TOTAL ELECTRIC ENERGY LOSSES POWER IN PQR SPATIAL COORDINATES

Purpose. To obtain relations determining the components of the total losses power with p-q-r power theory for three-phase four-wire energy supply systems, uniquely linking four components: the lowest possible losses power, losses power caused by the reactive power, losses power caused by the instantaneous active power pulsations, losses power caused by current flowing in the neutral wire. Methodology. We have applied concepts of p-q-r power theory, the theory of electrical circuits and mathematical simulation in Matlab package. Results. We have obtained the exact relation, which allows to calculate the total losses power in the three-phase four-wire energy supply system using three components corresponding to the projections of the generalized vectors of voltage and current along the pqr axis coordinates. Originality. For the first time, we have established a mathematical relationship between spatial representation of instantaneous values of the vector components and the total losses power in the three-phase four-wire energy supply systems. Practical value. We have elucidated an issue that using the proposed methodology would create a measuring device for determining the current value of the components of total losses power in three-phase systems. The device operates with measuring information about instantaneous values of currents and voltages.

ESTIMATING THE LIMIT POSSIBILITIES OF THE STEP CHARGING SYSTEM FOR CAPACITIVE ENERGY STORAGE

The aim of the article is to estimate the limit possibilities of step-by-step charging the capacitive energy storage which are caused by the achievement of a balance among the processes of the receiving and losing of electromagnetic energy. Originality. For the first time a step the charging system as a high power converter for pulsed load was considered, that allow to simplify similar charging systems and make its chipper while saving output characteristics and common quality. Methodology of the analysis applied is based on the classic electric circuits theory. All of the resulted carried out, were obtained as the differential equation solutions and its behavior was analyses analytically. Results. The basic diagram of the step-by-step charging system what is an alternative to the traditional variant with the step-up transformer was described. This system realizes the serial charge voltage increasing by the separate portions of energy, which has been, accumulated preliminary in the inductive energy storage. The formulas for estimating the limit possibilities of the step-by-step charging were got. These limits are caused by achieving a balance of the entering and losing electromagnetic energy. The applicability of the formulas was illustrated by numerical examples. Practical value. According to the results that were obtained, it is possible to note, that the step charging system is acceptable to be used as a high power converter for capacitive storage charging. References 5, figures 1.

A problem with inverse time for a singularly perturbed integro-differential equation with diagonal degeneration of the kernel of high order

We consider an algorithm for constructing asymptotic solutions regularized in the sense of Lomov (see [1], [2]). We show that such problems can be reduced to integro-differential equations with inverse time. But in contrast to known papers devoted to this topic (see, for example, [3]), in this paper we study a fundamentally new case, which is characterized by the absence, in the differential part, of a linear operator that isolates, in the asymptotics of the solution, constituents described by boundary functions and by the fact that the integral operator has kernel with diagonal degeneration of high order. Furthermore, the spectrum of the regularization operator (see below) may contain purely imaginary eigenvalues, which causes difficulties in the application of the methods of construction of asymptotic solutions proposed in the monograph [3]. Based on an analysis of the principal term of the asymptotics, we isolate a class of inhomogeneities and initial data for which the exact solution of the original problem tends to the limit solution (as ) on the entire time interval under consideration, also including a boundary-layer zone (that is, we solve the so-called initialization problem). The paper is of a theoretical nature and is designed to lead to a greater understanding of the problems in the theory of singular perturbations. There may be applications in various applied areas where models described by integro-differential equations are used (for example, in elasticity theory, the theory of electrical circuits, and so on).

OHM'S LAW IS THE GENERAL LAW OF EXACT SCIENCES

Ponte Academic JournalJul 2016, Volume 72, Issue 7 OHM'S LAW IS THE GENERAL LAW OF EXACT SCIENCESAuthor(s): Alexander Alexandrovich AntonovJ. Ponte - Jul 2016 - Volume 72 - Issue 7 doi: 10.21506/j.ponte.2016.7.9 Abstract:It is shown that Ohm�s law in the interpretation of Steinmetz and special theory of relativity are antagonists in solving the problem of physical reality of concrete imaginary numbers, since Ohm's law has solved this problem successfully, whereas special theory of relativity has postulated impossibility of its solving. Therefore, being influenced by the special theory of relativity the problem has not been solved in the theory of electrical circuits, and the question of physical reality of imaginary reactance of capacitors and inductors has been left open. The paper proves physical reality of imaginary numbers. Physical reality of capacitive and inductive reactances is proved, including by Ohm's law. And thereby it proves the fallacy of the current version of the special theory of relativity. The paper presents the adjusted version of the special theory of relativity, which enables to develop a hypothesis of the hidden Multiverse. Parallel universes of such a Multiverse are mutually invisible in relation to each other, as they are in different dimensions. The hypothesis is confirmed by the data obtained by WMAP and Planck spacecrafts. It also explains the astrophysical phenomenon of dark matter and dark energy, which, in turn, is an experimental confirmation of existence of the hidden Multiverse. Download full text:Check if you have access through your login credentials or your institution Username Password

Further Results on Resistance Distance and Kirchhoff Index in Electric Networks

In electric circuit theory, it is of great interest to compute the effective resistance between any pairs of vertices of a network, as well as the Kirchhoff index. LetQ(G)be the graph obtained fromGby inserting a new vertex into every edge ofGand by joining by edges those pairs of these new vertices which lie on adjacent edges ofG. The set of such new vertices is denoted byI(G). TheQ-vertex corona ofG1andG2, denoted byG1⊙QG2, is the graph obtained from vertex disjointQ(G1)andVG1copies ofG2by joining theith vertex ofV(G1)to every vertex in theith copy ofG2. TheQ-edge corona ofG1andG2, denoted byG1⊖QG2, is the graph obtained from vertex disjointQ(G1)andIG1copies ofG2by joining theith vertex ofI(G1)to every vertex in theith copy ofG2. The objective of the present work is to obtain the resistance distance and Kirchhoff index for composite networks such asQ-vertex corona andQ-edge corona networks.

選好度付セットベースデザイン（PSD）手法のフィルタ設計への適用の検討

Electrical design is usually made with the concepts based on the electric circuit theory. Nowadays it needs to consider the electromagnetic (EM) fields generated in devices, components, and equipment to achieve their expected performances and satisfy the electromagnetic compatibility (EMC) regulations as well. In such kind of design, it is required to pursue a solution which satisfies simultaneously multi-objective performances sometimes including conflicting requirements. In this paper, the application of a multi-objective satisfactory design method to electrical design is discussed. The method, named preference set-based design (PSD), is developed as a concurrent design method in the field of mechanical engineering. As a first application to electric and electronic fields, the method is applied to filter designs and its validity is discussed. Applied filter is an ordinary five-order low-pass filter composed of plural element parameters and objectives or performances of attenuation characteristics. In practical cases, some design uncertainties should be taken into account, for example an unnecessary magnetic fields coupling between inductors. Design solution expressed in terms of point value cannot easily and effectively handle the design uncertainties since there is no theoretical guarantee that the solution converges in such case. Such an uncertainty problem is treated in this study. By using the resultant parameter sets, the attenuation characteristics are analyzed and confirmed whether the required performances are satisfied.

Pushing the Wireless Data Rate to the Internet Speed

This paper intends to answer the question how to achieve wireless data rates that can catch up with current Internet speed, from a basic physics point of view. It is shown that the traditional electric circuit theory and design methodology that have been used for generations are unfortunately not adequate for wireless communications in the future. Instead, disruptive approaches, such as six-port modulators for processing of electromagnetic waves and optical pulses, should be employed to push up the wireless data rate above 100 Gb/s. The key variables to consider for high-speed digital communications are bandwidth, modulation order, and signal-to-noise ratio. In principle, it should be possible to achieve a wireless data rate at 100 Gb/s within the frequency spectrum below 20 GHz.

Memristive Model of the Barnacle Giant Muscle Fibers

The generation of action potentials (oscillations) in biological systems is a complex, yet poorly understood nonlinear dynamical phenomenon involving ions. This paper reveals that the time-varying calcium ion and the time-varying potassium ion, which are essential for generating action potentials in Barnacle giant muscle fibers are in fact generic memristors in the perspective of electrical circuit theory. We will show that these two ions exhibit all the fingerprints of memristors from the equations of the Morris–Lecar model of the Barnacle giant muscle fibers. This paper also gives a textbook reference to understand the difference between memristor and nonlinear resistor via analysis of the potassium ion-channel memristor and calcium ion-channel nonlinear resistor. We will also present a comprehensive in-depth analysis of the generation of action potentials (oscillations) in memristive Morris–Lecar model using small-signal circuit model and the Hopf bifurcation theorem.

Research Related Electromechanical Processes in an Asynchronous Traction Motor - Asynchronous Generator with Common Shaft Based on Field Model

Creating energy efficiency traction induction motors with frequency control for hybrid drive vehicles defines practical interest for new methods of testing and simulation. Tests of these machines, it is desirable to carry out with energy recovery in the motor-generator, where a common shaft unites the machines. At present, the system simulation of motor-generator is carried out on simplified models without saturation, surface effect, jagged cores, and non-sinusoidal voltage of frequency converters. A refined interrelated mathematical model of asynchronous motor and generator operating with a common shaft, based on the theory of electrical circuits and field theory. Models allow the related modelling and study of static and dynamic modes electrical machines taking into account the saturation, skin effect, toothed cores, non-sinusoidal voltage of the frequency inverter, and variation parameters of the windings.

Adjustment of the Special Theory of Relativity according to the Ohm’s Law

It is shown that the whole practice of using Ohm’s law in the theory of electrical circuits is actually a theoretical and experimental evidence for physical reality of imaginary numbers. Therefore, the current interpretation of the special theory of relativity, which denies physical reality of imaginary numbers, requires appropriate adjustment. The adjusted version of the special theory of relativity can explain the phenomena of dark matter and dark energy. Other exact sciences also require adjustment with regard to the principle of physical reality of imaginary numbers.