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Article
Publication date: 6 March 2009

Xiaohui Wang, David W.P. Thomas, Mark Sumner, John Paul and Sérgio H.L. Cabral

The purpose of this paper is to propose a robust method to estimate the parameters of Jiles‐Atherton model of ferromagnetic hysteresis by fitting the model to symmetrical…

835

Abstract

Purpose

The purpose of this paper is to propose a robust method to estimate the parameters of Jiles‐Atherton model of ferromagnetic hysteresis by fitting the model to symmetrical hysteresis loops. The performance of the method is evaluated by both theoretical and experimental data.

Design/methodology/approach

Jiles‐Atherton model with five parameters describes the hysteretic behaviour of ferromagnetic materials. To calculate the model parameters, the most common data displaying the hysteresis features are the hysteresis loops stimulated by symmetrical steady state excitations, e.g. sinusoidal sources. Using the characteristic equations at specific points on these hysteresis loops, the Jiles‐Atherton model parameters can be determined by curve fitting and numerical optimized iteration.

Findings

Practicality and robustness were not well considered by the conventional parameter estimation method: the initial curve starting from demagnetization is not always available and a direct iterative algorithm to solve the characteristic equations is sensitive to the initial values of the iteration and the evaluation order of the equations because of two main reasons. The first one is that the basic equation group has non‐unique solutions, which is caused by the nonlinearity of the characteristic equations and the fact that there are more unknown quantities (i.e. five model parameters) than the equations available; the second reason is the multimodal feature of the problem, which means that there are many local minima for the iteration algorithm to be trapped in. So curve fitting around the loop tips is proposed before numerical iteration. The goal is to make the initial values, particularly saturation magnetization Ms, not far away from the desired solution to increase the possibility of converging to a physical result. The optimized iterative method with the enhanced ability to avoid local minima and find global roots is then applied to obtain the model parameters.

Originality/value

The proposed method overcomes the difficulties of the other techniques which assume zero remanence. It is also robust as it is guaranteed to converge to physical solutions. The method can facilitate further development and it formed the preliminary basis of our earlier work, where the variation of the Jiles‐Atherton model parameters with different magnetic field strengths was investigated and applied to the simulation of transformer inrush current.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 28 no. 2
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 13 November 2007

Okan Ozgonenel, David W.P. Thomas and Christos Christopoulos

The purpose of this paper is to describe a technique for modeling transformer internal faults using transmission line modeling (TLM) method. In this technique, a model for…

806

Abstract

Purpose

The purpose of this paper is to describe a technique for modeling transformer internal faults using transmission line modeling (TLM) method. In this technique, a model for simulating a two winding single phase transformer is modified to be suitable for simulating an internal fault in both windings.

Design/methodology/approach

TLM technique is mainly used for modeling transformer internal faults. This was first developed in early 1970s for modeling two‐dimensional field problems. Since, then, it has been extended to cover three dimensional problems and circuit simulations. This technique helps to solve integro‐differential equations of the analyzed circuit. TLM simulations of a single phase transformer are compared to a custom built transformer in laboratory environment.

Findings

It has been concluded from the real time studies that if an internal fault occurs on the primary or secondary winding, the primary current will increase a bit and secondary current does not change much. However, a very big circulating current flows in the shorted turns. This phenomenon requires a detailed modeling aspect in TLM simulations. Therefore, a detailed inductance calculation including leakages is included in the simulations. This is a very important point in testing and evaluating protective relays. Since, the remnant flux in the transformer core is unknown at the beginning of the TLM simulation, all TLM initial conditions are accepted as zero.

Research limitations/implications

The modeling technique presented in this paper is based on a low frequency (up to a few kHz) model of the custom‐built transformer. A detailed capacitance model must be added to obtain a high‐frequency model of the transformer. A detailed arc model, aging problem of the windings will be applied to model with TLM + finite element method.

Originality/value

Using TLM technique for dynamical modeling of transformer internal faults is the main contribution. This is an extended version of an earlier referenced paper of the authors and includes inductance calculation, leakages calculation, and BH curve simulation while the referenced paper only includes piecewise linear inductance values. This modeling approach may help power engineers and power system experts understand the behavior of the transformer under internal faults.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 26 no. 5
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 5 January 2010

Wei Dong, Pericle Zanchetta and David W.P. Thomas

The knowledge of power network parameters (which are usually unknown or poorly quantified and cannot be measured directly) is very valuable for power system modelling, simulation…

390

Abstract

Purpose

The knowledge of power network parameters (which are usually unknown or poorly quantified and cannot be measured directly) is very valuable for power system modelling, simulation, protection and control; since it is fundamental for solving many problems such as minimizing the effect of voltage distortion, active filter control or relay setting. The purpose of this paper is to develop a new, easy, effective and reliable method for power network parameters identification.

Design/methodology/approach

The proposed identification method is based on current transient injections performed by a pulse width modulated power converter (which can be a rectifier or an active filter already installed in the network) and the analysis of the resultant network voltage response at the point of common coupling using genetic algorithms optimization.

Findings

Simulation tests show the effectiveness of the proposed identification strategy achieving negligible errors, even in practical conditions when measurement noise is included. It is also a very flexible method since the optimization routine can be updated or modified in order to improve the performance.

Originality/value

The developed method is non‐invasive, and uses only hardware already present on the power system, identifying the single parameters rather than the total impedance. It will provide improvements to several areas of power quality control. For example, when used within a stand‐alone piece of instrumentation, it will be possible to build up mesh equivalent networks of unknown power and distribution systems, which can then be used for load flow studies, protection or harmonic penetration prediction.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 29 no. 1
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 April 2003

Georgios I. Zekos

Aim of the present monograph is the economic analysis of the role of MNEs regarding globalisation and digital economy and in parallel there is a reference and examination of some…

101260

Abstract

Aim of the present monograph is the economic analysis of the role of MNEs regarding globalisation and digital economy and in parallel there is a reference and examination of some legal aspects concerning MNEs, cyberspace and e‐commerce as the means of expression of the digital economy. The whole effort of the author is focused on the examination of various aspects of MNEs and their impact upon globalisation and vice versa and how and if we are moving towards a global digital economy.

Details

Managerial Law, vol. 45 no. 1/2
Type: Research Article
ISSN: 0309-0558

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Article
Publication date: 1 May 1983

In the last four years, since Volume I of this Bibliography first appeared, there has been an explosion of literature in all the main functional areas of business. This wealth of…

16778

Abstract

In the last four years, since Volume I of this Bibliography first appeared, there has been an explosion of literature in all the main functional areas of business. This wealth of material poses problems for the researcher in management studies — and, of course, for the librarian: uncovering what has been written in any one area is not an easy task. This volume aims to help the librarian and the researcher overcome some of the immediate problems of identification of material. It is an annotated bibliography of management, drawing on the wide variety of literature produced by MCB University Press. Over the last four years, MCB University Press has produced an extensive range of books and serial publications covering most of the established and many of the developing areas of management. This volume, in conjunction with Volume I, provides a guide to all the material published so far.

Details

Management Decision, vol. 21 no. 5
Type: Research Article
ISSN: 0025-1747

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Article
Publication date: 1 June 1985

The librarian and researcher have to be able to uncover specific articles in their areas of interest. This Bibliography is designed to help. Volume IV, like Volume III, contains…

12736

Abstract

The librarian and researcher have to be able to uncover specific articles in their areas of interest. This Bibliography is designed to help. Volume IV, like Volume III, contains features to help the reader to retrieve relevant literature from MCB University Press' considerable output. Each entry within has been indexed according to author(s) and the Fifth Edition of the SCIMP/SCAMP Thesaurus. The latter thus provides a full subject index to facilitate rapid retrieval. Each article or book is assigned its own unique number and this is used in both the subject and author index. This Volume indexes 29 journals indicating the depth, coverage and expansion of MCB's portfolio.

Details

Management Decision, vol. 23 no. 6
Type: Research Article
ISSN: 0025-1747

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Book part
Publication date: 27 October 2016

Alexandra L. Ferrentino, Meghan L. Maliga, Richard A. Bernardi and Susan M. Bosco

This research provides accounting-ethics authors and administrators with a benchmark for accounting-ethics research. While Bernardi and Bean (2010) considered publications in…

Abstract

This research provides accounting-ethics authors and administrators with a benchmark for accounting-ethics research. While Bernardi and Bean (2010) considered publications in business-ethics and accounting’s top-40 journals this study considers research in eight accounting-ethics and public-interest journals, as well as, 34 business-ethics journals. We analyzed the contents of our 42 journals for the 25-year period between 1991 through 2015. This research documents the continued growth (Bernardi & Bean, 2007) of accounting-ethics research in both accounting-ethics and business-ethics journals. We provide data on the top-10 ethics authors in each doctoral year group, the top-50 ethics authors over the most recent 10, 20, and 25 years, and a distribution among ethics scholars for these periods. For the 25-year timeframe, our data indicate that only 665 (274) of the 5,125 accounting PhDs/DBAs (13.0% and 5.4% respectively) in Canada and the United States had authored or co-authored one (more than one) ethics article.

Details

Research on Professional Responsibility and Ethics in Accounting
Type: Book
ISBN: 978-1-78560-973-2

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Article
Publication date: 1 March 1992

John Conway O'Brien

A collection of essays by a social economist seeking to balanceeconomics as a science of means with the values deemed necessary toman′s finding the good life and society enduring…

1244

Abstract

A collection of essays by a social economist seeking to balance economics as a science of means with the values deemed necessary to man′s finding the good life and society enduring as a civilized instrumentality. Looks for authority to great men of the past and to today′s moral philosopher: man is an ethical animal. The 13 essays are: 1. Evolutionary Economics: The End of It All? which challenges the view that Darwinism destroyed belief in a universe of purpose and design; 2. Schmoller′s Political Economy: Its Psychic, Moral and Legal Foundations, which centres on the belief that time‐honoured ethical values prevail in an economy formed by ties of common sentiment, ideas, customs and laws; 3. Adam Smith by Gustav von Schmoller – Schmoller rejects Smith′s natural law and sees him as simply spreading the message of Calvinism; 4. Pierre‐Joseph Proudhon, Socialist – Karl Marx, Communist: A Comparison; 5. Marxism and the Instauration of Man, which raises the question for Marx: is the flowering of the new man in Communist society the ultimate end to the dialectical movement of history?; 6. Ethical Progress and Economic Growth in Western Civilization; 7. Ethical Principles in American Society: An Appraisal; 8. The Ugent Need for a Consensus on Moral Values, which focuses on the real dangers inherent in there being no consensus on moral values; 9. Human Resources and the Good Society – man is not to be treated as an economic resource; man′s moral and material wellbeing is the goal; 10. The Social Economist on the Modern Dilemma: Ethical Dwarfs and Nuclear Giants, which argues that it is imperative to distinguish good from evil and to act accordingly: existentialism, situation ethics and evolutionary ethics savour of nihilism; 11. Ethical Principles: The Economist′s Quandary, which is the difficulty of balancing the claims of disinterested science and of the urge to better the human condition; 12. The Role of Government in the Advancement of Cultural Values, which discusses censorship and the funding of art against the background of the US Helms Amendment; 13. Man at the Crossroads draws earlier themes together; the author makes the case for rejecting determinism and the “operant conditioning” of the Skinner school in favour of the moral progress of autonomous man through adherence to traditional ethical values.

Details

International Journal of Social Economics, vol. 19 no. 3/4/5
Type: Research Article
ISSN: 0306-8293

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Article
Publication date: 1 February 1974

Frances Neel Cheney

Communications regarding this column should be addressed to Mrs. Cheney, Peabody Library School, Nashville, Term. 37203. Mrs. Cheney does not sell the books listed here. They are…

411

Abstract

Communications regarding this column should be addressed to Mrs. Cheney, Peabody Library School, Nashville, Term. 37203. Mrs. Cheney does not sell the books listed here. They are available through normal trade sources. Mrs. Cheney, being a member of the editorial board of Pierian Press, will not review Pierian Press reference books in this column. Descriptions of Pierian Press reference books will be included elsewhere in this publication.

Details

Reference Services Review, vol. 2 no. 2
Type: Research Article
ISSN: 0090-7324

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Article
Publication date: 1 March 1999

Allan Metz

President Bill Clinton has had many opponents and enemies, most of whom come from the political right wing. Clinton supporters contend that these opponents, throughout the Clinton…

894

Abstract

President Bill Clinton has had many opponents and enemies, most of whom come from the political right wing. Clinton supporters contend that these opponents, throughout the Clinton presidency, systematically have sought to undermine this president with the goal of bringing down his presidency and running him out of office; and that they have sought non‐electoral means to remove him from office, including Travelgate, the death of Deputy White House Counsel Vincent Foster, the Filegate controversy, and the Monica Lewinsky matter. This bibliography identifies these and other means by presenting citations about these individuals and organizations that have opposed Clinton. The bibliography is divided into five sections: General; “The conspiracy stream of conspiracy commerce”, a White House‐produced “report” presenting its view of a right‐wing conspiracy against the Clinton presidency; Funding; Conservative organizations; and Publishing/media. Many of the annotations note the links among these key players.

Details

Reference Services Review, vol. 27 no. 1
Type: Research Article
ISSN: 0090-7324

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