Electrical Engineering Community Research Articles

Working, reflected and detrimental active powers

The active power P is one of the best established power quantities, commonly regarded as the useful power. There is awareness in the electrical engineering community, however, that some components of this power in systems with non-sinusoidal and asymmetrical voltages and currents are not useful for customers. Owing to an increase in cost of energy, increase in expectations towards the supply reliability and security, electrical power system technology faces a need of extensive changes. Even the best established concepts can be challenged and revised. Therefore the concept of the active power is revised in this study. It is shown that the active power P can be decomposed into three components of different usefulness, referred to as working, reflected and detrimental active powers. It is shown, that energy accounts based on the working, instead of the active energy, might create economic incentives for reducing harmonics and asymmetry both on the energy provider and the customer sides. This idea challenges deeply rooted standards; therefore the study can be regarded only as an initiation of a debate on the very sensitive issue of rationalisation of energy accounts in systems with non-sinusoidal and asymmetrical voltages and currents.

An aid for teaching hybrid propulsion systems with emphasis on their electric drive unit

PurposeThe purpose of this paper is to propose an approach to teach to post‐graduate students the basis of hybrid propulsion systems (HPS) with emphasis on their electric drive unit.Design/methodology/approachFollowing the introduction of the basic topologies of HPS, a case study is focused with an analysis of its current features. Of particular interest, those related to the flux‐weakening range extension and the cost‐effectiveness improvement are rethought in an attempt to stimulate the innovative capabilities of the students.FindingsThe adopted methodology has been integrated in a master course and has been found attractive and informative by the students.Practical implicationsThe proposed teaching approach should be complemented by appropriate laboratory courses.Originality/valueThanks to the proposed methodology, the basis of HPS is no longer restricted to a selected population of the electrical engineering community.

ELLEIEC Project: A contribution to harmonise the European Higher Education Area

This paper presents the objective and current state of the ELLEIEC [1] project (Enhancing Lifelong Learning for the Electrical and Information Engineering Community). The implementation of the Bologna process offers us an opportunity to create a European dimension to our EIE (Electrical and Information Engineering) Degrees in the World Wide education area by convergence of our curricula and strengthening the links and sharing of resources between European Higher Education Institutions.

Numerical convergence and physical fidelity analysis for Maxwell’s equations in metamaterials

In this paper, we develop a leap-frog mixed finite element method for solving Maxwell’s equations resulting from metamaterials. Our scheme is similar to the popular Yee’s FDTD scheme used in electrical engineering community, and is preferable for three dimensional large scale modeling since no storage of the large coefficient matrix is needed. Our scheme is proved to obey the Gauss’s law automatically if the initial fields satisfy that. Furthermore, the conditional stability and optimal error estimate for the proposed scheme are proved. To our best knowledge, we are unaware of any other publications devoted to the convergence analysis of this leap-frog explicit scheme for Maxwell’s equations even in a simple medium, while our results for metamaterials automatically reduce to the standard Maxwell’s equations in vacuum by dropping some terms resulting from the constitutive equations. Numerical results confirming our analysis are presented.

Handbook of Biosensors and Biochips (Marks, R.S., et al., Eds.; 2007) [Book Review

This book is meant to serve as a reference for those wishing to obtain a broad overview of biosensors and biochips. It includes more than 80 articles from over 150 contributors from academia, governmental institutions, and industry. The entire work is divided into ten parts spanning two volumes. Each part begins with a one- to three-page introduction, written by one of the editors, which provides a general description of each article in the section and helpful commentary that ties all the articles together. Some of the topics covered include: a general overview of biosensor and bioarray technologies and the history of modern biosensor development; biological and molecular recognition systems; biological-material interfaces; tranducer technologies; array technologies; data analysis; applications; and commercialization and regulatory issues. The book is recommended for those involved in signal processing research as well as to the broader electrical and biomedical engineering communities.

Numerical methods in the simulation of charge transport in solid dielectrics

This paper introduces some numerical methods pertaining to the simulation of charge transport in solid dielectrics that can be of interest to the electrical engineering community. These methods are generally scattered over numerical analysis and computing literature making difficult for the non-specialist to select the appropriate computing schemes. In the first part we consider an example of a set of physical parameters needed to describe charge transport and we introduce mathematical equations that must be solved. A series of numerical schemes are compared for one-dimensional convection problems in a second part. Numerical results show that a third order upwind scheme named QUICKEST, combined with a flux limiter (ULTIMATE) is competent for the resolution of the transport equation in solid dielectrics, avoiding numerical oscillations and numerical diffusion. The third part deals with numerical resolution of the Poisson's equation comparing two different methods.

The pulsed electro-acoustic technique in research on dielectrics for electrical engineering. Today's achievements and perspectives for the future

The pulsed electro-acoustic technique is presented to the Electrical Engineering community where it can find many applications, from the development of improved materials for electrical insulation to the control of electrostatic surface discharge (ESD) phenomena. After a short introduction of the space charge problem, we introduce the technique itself and we show how consistent quantitative information can be extracted from this simple method taking examples of dielectrics under field or charged by an electron beam. Non-polar and polar materials are considered and it is shown that space charge and polarization effects can be separated from the spectra analysis. In a last part, we review new perspectives open by this technique to understand and to model electrical transport in dielectrics

Simple theoretical estimation of the dielectric strength of gases

Understanding how a gas is able to strongly insulate electric devices is certainly of great importance to the electrical engineering community. More precisely, modeling how a dielectric gas stops an electric current requires to understand what makes a gas a good dielectric, or in other words, what makes a gas presenting a high dielectric strength (DS). We show how to easily estimate the DS of a gas by calculating its ability to absorb light.

Analysis of the finite difference time domain technique to solve the Schrödinger equation for quantum devices

An extension of the finite difference time domain is applied to solve the Schrödinger equation. A systematic analysis of stability and convergence of this technique is carried out in this article. The numerical scheme used to solve the Schrödinger equation differs from the scheme found in electromagnetics. Also, the unit cell employed to model quantum devices is different from the Yee cell used by the electrical engineering community. A bound for the time step is derived to ensure stability. Several numerical experiments in quantum structures demonstrate the accuracy of a second order, comparable to the analysis of electromagnetic devices with the Yee cell.

A thorough look at the nonuniqueness of the electromagnetic scattering integral equation solutions as compared to the scalar acoustic ones

It is well‐known that solutions of electromagnetic scattering integral equations of the first or second kind (EFIE and MFIE) for perfectly electric or perfectly magnetic conducting scatterers are nonunique for those frequencies which correspond to interior Maxwell resonances of the scatterer; hence, the null spaces of the respective interior problem operators are under concern. In principle, all mathematical facts and proofs regarding this problem and cited in this paper are available from the book by Colton and Kress [1983], yet, these authors mainly concentrate on single and double layer potentials for the scalar acoustic (Dirichlet and Neumann) as well as the magnetic dipole layer ansatz for the perfectly electric conducting (Maxwell) problem and treat the Huygens‐type representation, which is more common in the electrical engineering community, not in the same detail. This might be the reason that part of the electrical engineering literature suffers from some confusion regarding the proper null spaces and their physical relevance, in particular, if the electromagnetic problem is considered in 2‐D, where it reduces to scalar TM/TE‐problems. The present contribution comments on these issues emphasizing that the null spaces of 2‐D electromagnetics are the nonphysical null spaces originating from the Huygens‐type representation of scalar acoustics.

Explosion prevention−the broader picture

Over 100 years, the electrical engineering community has developed and refined a whole series of ways to create electrical equipment that can be used safely where flammable substances are present in the surroundings. The initial designs were intended to cope with gas atmospheres in mines. These were followed by designs for a wider range of applications in the expanding chemical and oil refining industries, while bringing up the rear were standards for use in dusty atmospheres, as found, for example, in flour milling, wood finishing and some chemical processes. Despite all this effort, we have not stopped fires and explosions from occurring, sometimes with quite localised effects, and sometimes with devastating consequences. It is clearly necessary to address not just the ignition risks from electrical equipment, but all the potential sources of ignition in a plant, and other approaches to making a site acceptably safe. The author discusses ignition sources, avoidance of explosive atmospheres, measuring vapour levels, mitigation measures, European Directives, nonelectrical equipment standards, and equipment reliability. The author concludes that with so many uncertainties in the equation, perhaps it is not wise to base safety on the single technique of avoiding ignition sources, unless the plant is extremely simple.

Get a clear view of simulated and measured data

Present-day operating systems have graphical user interfaces (GUI) that are of great help in designing good user interfaces for application programs. Also, there have been dramatic improvements in computer power and power-to-price ratio. Acknowledgement is growing, even in technical environments, that good man-machine interfaces (MMI) have so many advantages that they are worth the effort of design and implementation. A good MMI can reduce the chance of making trivial errors that could be detected only very late during the simulation process, resulting in a great deal of wasted time. Nevertheless, in the electrical engineering community, programs that are not optimal on the MMI side are still in use. This article focuses on a study of the MMI main issues for a plotting program to visualize simulation and measurement data effectively. The resulting program, PlotXY, was developed in the rapid application development (RAD) environment of Borland C++ Builder, which is distributed for free and described in this article, along with the main ideas behind its interface.

Comparison of Analytical Calculations to Finite-Difference Time-Domain Simulations of One-Dimensional Spatially Varying Anisotropic Liquid Crystal Structures

There is a need for an accurate optical simulation tool for liquid crystal structures with director variations in more than one dimension. Finite-difference time-domain (FDTD) computation of Maxwell's equations is one approach to consider. The FDTD method has been in use in the electrical engineering community for years, but has only recently been applied to liquid crystal structures. Little is known about the accuracy of FDTD simulations of typical liquid crystal structures, in which the dielectric tensor can undergo large local spatial variations. This paper compares FDTD simulations and analytic solutions of two liquid crystal problems: the twisted-nematic cell and Bragg reflection from a planar cholesteric layer.

Chairman's corner IEEE SAC

Why do we have student activities in the IEEE? It is because the IEEE leadership recognizes where the future practitioners of the electrical engineering profession, and the future strength of the Institute, will come from. The well-being of the electrical engineering community and the quality of its contribution to society depend on the preparation of the graduates entering the field. The IEEE contributes to that preparation through student activities.

Abstract: A quarter of a century of magnetism: Personal reminiscences

The 25 years that have elapsed since the first Magnetism Conference constitute a virtual history of magnetism in the U. S. At the first post-war International Conference on Magnetism held in Grenoble in 1950 (four years prior to the first of the regular U. S. Conferences on Magnetism that were the joint creation of the Physics and Electrical Engineering communities) fewer than ten Americans participated. Then, as two years later at the Maryland Conference, the focus was on ferromagnetism, the magnetization curve, domain wall motions and a brief nod to the then relatively new phenomena of ferrimagnetism, nuclear magnetism and neutron diffraction. The only concession to theory at Maryland was an evening symposium on ferromagnetic exchange that will be remembered by those who attended primarily for the controversy engendered therein. The explosive growth of the field in the subsequent decade is probably as much a consequence of the technological emphasis on applications principally in computers as it is a result of the new theoretical powers made available by those same computers. In an aesthetic sense, the impact that magnetism research has had on kindred fields of science and engineering from lasers to DNA is testimony to the unboundedness of scientific inquiry whatever the initial motivation. It is probably in its impact on the rest of the world of science and engineering that magnetism research today holds its greatest potential.