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Article
Publication date: 13 September 2011

P. Alotto, M. Guarnieri, F. Moro and A. Stella

The purpose of this paper is to simulate in the time domain three‐dimensional electrical, thermal, mechanical coupled contact problems arising in electric resistance…

Abstract

Purpose

The purpose of this paper is to simulate in the time domain three‐dimensional electrical, thermal, mechanical coupled contact problems arising in electric resistance welding (ERW) processes.

Design/methodology/approach

A three‐dimensional multiphysical numerical model for analyzing contact problems is proposed. Electrical and thermal field equations in bulk domains are discretized with the cell method (CM). Welding resistance at contact interfaces is described locally by synthetic statistic parameters and contacting domains are matched together by a non‐overlapping domain decomposition method. Contact pressure distribution is resolved by a finite‐element procedure. The model is validated with 3D FEM software package.

Findings

The semi‐analytical model describing the electric and thermal resistances at contact interfaces can be easily embedded in CM formulations, where problem variables are expressed directly in integral form. Compatibility conditions between contact members are enforced by a domain decomposition approach. System conditioning and computing time are improved by a solution strategy based on the Schur complement method.

Research limitations/implications

The electrical‐thermal analysis is not coupled strongly with the mechanical analysis and contact pressure distribution is assumed to be not depending on thermal stresses, which can be considerable near the contact area where localized joule heating occurs.

Practical implications

Resistance welding processes involve mechanical, electrical, and thermal non‐linear coupled effects that cannot be simulated by standard commercial software packages. The proposed numerical model can be used instead for designing and optimizing ERW processes.

Originality/value

The paper shows that numerical modeling of ERW processes requires a careful prediction of the localized joule heating occurring at the electrode‐material interface. This effect is reconstructed by the proposed approach simulating coupled electrical, thermal, and mechanical effects on different spatial scales.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 30 no. 5
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 6 March 2017

Lorenzo Codecasa, Federico Moro and Piergiorgio Alotto

This paper aims to propose a fast and accurate simulation of large-scale induction heating problems by using nonlinear reduced-order models.

Abstract

Purpose

This paper aims to propose a fast and accurate simulation of large-scale induction heating problems by using nonlinear reduced-order models.

Design/methodology/approach

A projection space for model order reduction (MOR) is quickly generated from the first kernels of Volterra’s series to the problem solution. The nonlinear reduced model can be solved with time-harmonic phasor approximation, as the nonlinear quadratic structure of the full problem is preserved by the projection.

Findings

The solution of induction heating problems is still computationally expensive, even with a time-harmonic eddy current approximation. Numerical results show that the construction of the nonlinear reduced model has a computational cost which is orders of magnitude smaller than that required for the solution of the full problem.

Research limitations/implications

Only linear magnetic materials are considered in the present formulation.

Practical implications

The proposed MOR approach is suitable for the solution of industrial problems with a computing time which is orders of magnitude smaller than that required for the full unreduced problem, solved by traditional discretization methods such as finite element method.

Originality/value

The most common technique for MOR is the proper orthogonal decomposition. It requires solving the full nonlinear problem several times. The present MOR approach can be built directly at a negligible computational cost instead. From the reduced model, magnetic and temperature fields can be accurately reconstructed in whole time and space domains.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 36 no. 2
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 7 March 2008

J.D. Lavers

To provide a selective bibliography for researchers and graduate students who have an interest in induction processes applied to the electromagnetic processing of materials.

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Abstract

Purpose

To provide a selective bibliography for researchers and graduate students who have an interest in induction processes applied to the electromagnetic processing of materials.

Design/methodology/approach

The objective is to provide references that identify seminal, early work, and references that represent the current state of the art. References are listed in categories that cover the broad range of induction modeling and application issues.

Findings

A brief overview of the key areas in induction processing of materials is provided, but greater emphasis and space is devoted to the references provided.

Research limitations/implications

The middle years of each topic area are not covered.

Practical implications

A very comprehensive coverage of material is provided to those with an interest in induction processing of materials.

Originality/value

This paper fulfils an identified information/resources need.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 27 no. 2
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 16 November 2010

Massimo Guarnieri and Federico Moro

The purpose of this paper is to simulate passive proton exchange membrane fuel cells (PEMFCs) for portable electronic devices by means of a non‐linear lumped circuit based…

Abstract

Purpose

The purpose of this paper is to simulate passive proton exchange membrane fuel cells (PEMFCs) for portable electronic devices by means of a non‐linear lumped circuit based on electrical, mass transfer and electro‐kinetic equations.

Design/methodology/approach

Electrical, mass transfer and electro‐kinetic equations are combined in order to derive a non‐linear lumped circuit. The dynamic circuit model is tested in realistic operating conditions.

Findings

An original equivalent circuit model for simulating the transient behavior of passive PEMFCs is proposed. The PEMFC is represented as a non‐linear equivalent circuit with controlled lumped parameters depending on pressure, temperature, hydration, and system capacity.

Research limitations/implications

Lumped parameters are synthesized assuming a one‐dimensional fuel cell model since layer thicknesses are much smaller than other dimensions. Heat generation and transfer are not modeled even though lumped parameters depend on temperature.

Practical implications

The proposed circuit model can be implemented directly in circuit simulators for designing power management units needed to interface small‐passive PEMFCs and portable electronics such as PDAs, laptops, or mobile phones.

Originality/value

The fuel cell is represented as a non‐linear controlled generator whose parameters are derived directly from multiphysics equations rather than empirical relationships. The dynamic behaviour of PEMFCs can be simulated on completely different times scales, i.e. during transients or during the discharge phase.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 29 no. 6
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 15 November 2011

Piergiorgio Alotto

The purpose of this paper is to show that the performance of differential evolution (DE) can be substantially improved by a combination of techniques. These enhancements…

Abstract

Purpose

The purpose of this paper is to show that the performance of differential evolution (DE) can be substantially improved by a combination of techniques. These enhancements are applicable to both single and multiobjective problems. Their combined use allows the optimization of complex 3D electromagnetic devices.

Design/methodology/approach

DE is improved by a combination of techniques which are applied in a cascade way and their single and combined effect is tested on well‐known benchmarks and domain‐specific applications.

Findings

It is shown that the combined use of enhancement techniques provides substantial improvements in the speed of convergence for both single and multiobjective problems.

Research limitations/implications

The increased speed of convergence may come at the price of a somewhat decreased robustness. However, such behavior is justified by the CPU time constraints under which the optimization has to be performed.

Practical implications

The proposed approach appears to be an efficient general purpose stochastic optimizer for electromagnetic design problems.

Originality/value

This paper explorers the combined use of many of the most recent and successful algorithmic improvements to DE and applies them to both single and multiobjective problems.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 30 no. 6
Type: Research Article
ISSN: 0332-1649

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Book part
Publication date: 8 October 2018

Christin L. Munsch and Elizabeth S. Zack

An accelerometer is a device that measures force due to gravity or a change in speed or direction of travel. This paper describes accelerometers and their application in…

Abstract

Purpose

An accelerometer is a device that measures force due to gravity or a change in speed or direction of travel. This paper describes accelerometers and their application in other disciplines and, by way of an example, explores the utility of accelerometers for studying aggression. We end with a discussion of additional ways accelerometers might be used in group processes research.

Methodology

We first review the use of accelerometers in other disciplines. We then present the results of four studies that demonstrate the use of accelerometers to measure aggression. Study 1 establishes the measure’s concurrent validity. Study 2 concerns its stability and representative reliability. Study 3 seeks to establish the measure’s predictive validity by associating it with an existing measure. Study 4 demonstrates the ability of accelerometers to address a sociological research question.

Findings

In Studies 1 and 2, we find that accelerometers can be used to differentiate between distinct levels of aggression. In Study 3, we find that men’s average peak acceleration correlates with a previously validated measure of aggression. Study 4 uses accelerometers to reproduce a well-established finding in the aggression literature.

Practical Implications

We conclude that accelerometers are a flexible tool for group processes’ researchers and social scientists more broadly. Our findings should prove useful to social scientists interested in measuring aggression or in employing accelerometers in their work.

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Book part
Publication date: 10 June 2014

Now well into the 21st century, the world’s most powerful organizations’ highest executive levels and boards of directors still fail to represent a diverse collection of…

Abstract

Now well into the 21st century, the world’s most powerful organizations’ highest executive levels and boards of directors still fail to represent a diverse collection of people shaped by unique social identity dimensions according to age, class, culture, ethnicity, faith/spirituality, gender, physical/psychological ability, sexual orientation, and more. Offered in this book is an investigation into why a homophily framework, or a similarity-attraction hypothesis, continues to perpetuate leadership by predominantly Caucasian/White males and reinforces barriers that keep qualified people possessing a multiplicity of social identity dimensions from achieving their full human potential.

To understand interactive processes through which discrimination is reproduced in the workplace, social identity theorists explore connections between ways that people create social identity and that organizations become socially constructed. Social identity theory explains how people seek to develop oneness with groups that help them to develop and/or to enhance positive self-esteem – and to better understand how people develop notions of high-status ingroups and low-status outgroups. Both of these frameworks are central to this book’s attention to difference in organizations. Difference is positioned as a positive advance in organizational dynamics; advocating respect and appreciation for multiple and intersecting social identities – not for profitability and other business case reasons – but because it is morally justified to eradicate inequitable and exclusionary practices in organizations. This book offers an introduction to doing difference research by introducing a number of theoretical underpinnings, addressing methodological challenges, and presenting a wide cross-section of numerous bodies of literature which have been attending to difference work. Chapter 1 is divided into subthemes of: applying social identity theory, emphasizing the “center” and the “margin,” managing organizational climate, and avoiding business case thinking and other flawed models by advocating for real diversity.

Details

Practical and Theoretical Implications of Successfully Doing Difference in Organizations
Type: Book
ISBN: 978-1-78350-678-1

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Book part
Publication date: 29 October 2018

H. Colleen Stuart, Sue H. Moon and Tiziana Casciaro

This chapter examines the implications of career achievement for divorce, and whether they differ for men and women. Consistent with theory suggesting that women’s…

Abstract

This chapter examines the implications of career achievement for divorce, and whether they differ for men and women. Consistent with theory suggesting that women’s workplace achievement violates traditional expectations of gender and marriage, therefore creating domestic strain, the authors predict that career achievement is associated with a greater risk of divorce for women, but not for men. Using data from the Academy Awards, the authors find that for women, a sudden shift in achievement from winning an Oscar increases their risk of divorce compared to Best Actress nominees. There was no difference in the risk of divorce between Best Actor winners and nominees. The authors additionally examine two potential mitigating factors: whether the actor was already successful at the time of their marriage, and whether their spouse was comparably successful. For Best Actress winners, but not for Best Actor winners, the authors find evidence for the latter, indicating that women’s marriages are more stable when spouses are equally successful, or when relative achievement within the couple aligns with broadly-held norms of traditional marriage.

Details

The Work-Family Interface: Spillover, Complications, and Challenges
Type: Book
ISBN: 978-1-78769-112-4

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Article
Publication date: 9 September 2013

Piergiorgio Alotto, Massimo Guarnieri, Federico Moro and Andrea Stella

The purpose of this paper is to show the main features of the redox flow battery technology, present the current state-of-the-art of both industrial and research systems…

Abstract

Purpose

The purpose of this paper is to show the main features of the redox flow battery technology, present the current state-of-the-art of both industrial and research systems and to highlight the main research challenges.

Design/methodology/approach

The study is based on an extensive survey of recent literature as well as on the authors' own experience in the modelling of RFB systems.

Findings

RFBs present unique features which make them suitable for distributed storage and thus particularly interesting in the context of smart grids. Current research aims at resolving some outstanding issues which still limit the widespread use of RFBs.

Practical implications

A more widespread use of energy storage technologies, and RFBs in particular, will allow a much higher penetration of renewable energy sources.

Originality/value

The paper presents one of the few comprehensive studies on RFBs including both technological and modelling aspects.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 32 no. 5
Type: Research Article
ISSN: 0332-1649

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Book part
Publication date: 10 June 2014

Social identity shaped by sexual orientation is unique because it is invisible (as compared to age and some ethnic identities); a circumstance that may activate homophobia…

Abstract

Social identity shaped by sexual orientation is unique because it is invisible (as compared to age and some ethnic identities); a circumstance that may activate homophobia perceptions when an individual’s sexual orientation becomes fodder for speculation. Chapter 7 enjoins a wide variety of related issues in order to sharpen a focus on sex in the workplace; love and sex in the literal sense, as well as social identity shaped by sexual orientation, sex-based discrimination, sex as political action, and important ways that sex intersects with other social identity dimensions including age, gender, ethnicity/race, and socioeconomic status. An important distinction made throughout the chapter is the degree that protections are offered to various groups with regard to sex and work. These protections (or lack of them) are critical for gays, lesbians, bisexuals, the transgendered, and queer or questioning people who consider whether or not to disclose information about their sexual identity at work.

While many multinational corporations have adopted policies or guidelines and implemented programs to communicate an inclusive perspective on sexual identity in the workplace and to promote diversity training for all employees, too few workplaces around the globe offer legal protections for workers relative to sexual identity. People are subject to workplace discrimination whether they are gay or lesbian, or simply appear to be so and sexual harassment according to gender remains a fixture of organizations. To explore the organizational research on sexuality, Chapter 7 attends to subthemes of: love, lust, and sex-based harassment in the workplace; how organizations address sexual orientation and sex-based harassment in the workplace; managing one’s sexual identity in the workplace; and intersectionalities of sexual identity with ethnicity, gender, and social class.

Details

Practical and Theoretical Implications of Successfully Doing Difference in Organizations
Type: Book
ISBN: 978-1-78350-678-1

Keywords

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