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Article
Publication date: 1 January 2006

A. Benabou, L. Vandenbossche, J. Gyselinck, S. Clenet, L. Dupré and P. Dular

Mechanical stress can heavily affect the magnetic behaviour law in ferromagnetic materials. This paper, aims to take into account the effect of mechanical stress into a

350

Abstract

Purpose

Mechanical stress can heavily affect the magnetic behaviour law in ferromagnetic materials. This paper, aims to take into account the effect of mechanical stress into a hystreresis model. This model is implemented in a finite element analysis code and tested in the case of a simple system.

Design/methodology/approach

A simple extension of the classical Preisach model is proposed, in which a function linked to the Preisach density is parameterized using the mechanical stress as a supplementary parameter. The methodology is based on experimental measurements for identifying the required function. As a first approach, a linear interpolation is used between the measurements in order to have a continuous evolution of the magneto‐mechanical behaviour. This model has been tested in the case of a steel sheet in which width is not constant in order to obtain a non‐uniform distribution of stress and magnetic flux density.

Findings

The model can predict the magneto‐mechanical behaviour with a good accuracy in the case of tensile stress. Implementation of the model in finite element analysis has shown that the model can predict the behaviour of steel sheet subject to a non‐uniform stress distribution.

Originality/value

This paper shows that a classical hysteresis model can be extended to take into account the magneto‐mechanical behaviour. This is useful for the design of electrical machines which are subject to non‐negligible mechanical stress.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 25 no. 1
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 January 2006

S. Taïbi, A. Tounzi and F. Piriou

Aims to determine the magnetic parameters at no‐load of a variable reluctance machine excited by DC and AC currents.

345

Abstract

Purpose

Aims to determine the magnetic parameters at no‐load of a variable reluctance machine excited by DC and AC currents.

Design/methodology/approach

Presents the linear analytical model used to determine the electro‐magnetic variables of a stator current excited reluctance machine. The 2D FEM approach is also introduced. Then the prototype designed in the laboratory is presented and its magnetic characteristics determined. The results are calculated using both models and compared with the experimental values.

Findings

According to the different results, apart from the atypical E(Ie) characteristic, for both excitation models, the doubly slotted machine excited by current in the stator can be modelled in a manner similar to that of a smooth rotor synchronous machine with an electromagnetic gear box.

Originality/value

This paper has succeeded in determining the magnetic parameters at no‐load of a variable reluctance machine excited by DC and AC currents.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 25 no. 1
Type: Research Article
ISSN: 0332-1649

Keywords

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Book part
Publication date: 19 January 2005

Thomas de Graaff and Henri L.F. de Groot

Abstract

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Urban Dynamics and Growth: Advances in Urban Economics
Type: Book
ISBN: 978-0-44451-481-3

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Article
Publication date: 4 March 2019

Joseph Deutsch, Audrey Dumas and Jacques Silber

The purpose of this paper is to analyze the determinants of scholastic performance using an efficiency analysis perspective.

257

Abstract

Purpose

The purpose of this paper is to analyze the determinants of scholastic performance using an efficiency analysis perspective.

Design/methodology/approach

The authors apply data envelopment analysis (DEA) at the pupil level using the 2009 PISA survey in Azerbaijan. Before applying DEA with multiple outputs, this paper integrates the maximum amount of available information on inputs via the use of correspondence analysis.

Findings

The results show that scholastic efficiency depends positively on the externalities due to the resources of the school and to a peer effect. The analysis of the determinants of these externalities shows how they influence scholastic performance and has some policy implications.

Practical implications

Education policies should promote the resource externality, because its effect is more homogeneous among pupils. The mechanisms generating school externalities should be taken into consideration by educational authorities, when allocating resources to school and should give some guidelines about how to use these resources and how to manage a school in order to promote peer effects externalities.

Originality/value

The authors distinguish various sources of efficiency: that of the pupil and that due to school externalities operating via resources and peer effects. The authors relate the efficiency due to school externalities to individual, family and school characteristics.

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Article
Publication date: 29 April 2019

Adam Jakubas, Radosław Jastrzębski and Krzysztof Chwastek

The purpose of this paper is to examine the effect of varying compaction pressure on magnetic properties of self-developed soft magnetic composite (SMC) cores. The change in shape…

135

Abstract

Purpose

The purpose of this paper is to examine the effect of varying compaction pressure on magnetic properties of self-developed soft magnetic composite (SMC) cores. The change in shape of ferromagnetic hysteresis curves has – in turn – the impact on the values of hysteresis model parameters. The phenomenological GRUCAD model is chosen for description of hysteresis curves.

Design/methodology/approach

Several cylinder-shaped cores have been made from a mixture of iron powder and suspense polyvinyl chloride using a hydraulic press with a form and a band with a thermocouple for controlling heat treatment conditions. The only varying parameter in the study is the compaction pressure. The magnetic properties of developed cores have been measured using a computer-acquisition card and LabView software. The obtained hysteresis curves are fitted to the equations of the phenomenological GRUCAD model. This description is compliant with the laws of irreversible thermodynamics. The variations of model parameters are presented as functions of compacting pressure.

Findings

The compaction pressure has a significant impact on magnetic properties of self-developed SMC cores. The paper provides a number of charts useful for checking how the parameters of the hysteresis model are affected.

Research limitations/implications

The present paper is limited to modelling symmetrical loops only. Description of more complex magnetization cycles is postponed to another, forthcoming paper.

Practical implications

The GRUCAD hysteresis model may be a useful tool for the designers of magnetic circuits. Its parameters depend on the processing conditions (in this study – the compaction pressure) of the SMC cores.

Originality/value

Modelling of magnetic properties of SMC cores has been carried so far using some well-known description like Preisach, Takács and Jiles–Atherton proposals. The GRUCAD model has a number of advantages, and it may be a useful alternative to the latter formalism. So far it has been used for description of hysteresis curves in conventional materials like non-oriented and grain-oriented electrical steels. In the present work, it is applied to novel SMC materials.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 38 no. 4
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 September 2004

Abdelkader Benabou, Stéphane Clénet and Francis Piriou

In this communication, the Preisach and Jiles‐Atherton models are studied to take hysteresis phenomenon into account in finite element analysis. First, the models and their…

648

Abstract

In this communication, the Preisach and Jiles‐Atherton models are studied to take hysteresis phenomenon into account in finite element analysis. First, the models and their identification procedure are briefly developed. Then, their implementation in the finite element code is presented. Finally, their performances are compared with an electromagnetic system made of soft magnetic composite. Current and iron losses are calculated and compared with the experimental results.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 23 no. 3
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 14 November 2017

Elaine Wallace, Isabel Buil and Leslie de Chernatony

This study aims to investigate the relationship between young people’s Conspicuous Donation Behaviour (CDB) on social media platforms and their offline donation behaviour…

9368

Abstract

Purpose

This study aims to investigate the relationship between young people’s Conspicuous Donation Behaviour (CDB) on social media platforms and their offline donation behaviour, specifically intentions to donate and volunteer time. It also explores materialism, self-esteem and self-monitoring as CDB trait antecedents, as a form of conspicuous consumption on social media. Finally, it considers the influence of altruism on these relationships.

Design/methodology/approach

A survey was conducted of regular Facebook users mentioning a charity brand on Facebook in the past year. Data from 234 participants were analysed and hypotheses tested using structural equation modeling.

Findings

Results confirm two forms of CDB – self and other-oriented. Materialistic consumers are more likely to engage in both forms of CDB on Facebook. High self-esteem increases self-oriented CDB; high self-monitoring increases other-oriented CDB. Self-oriented CDB is positively associated with donation intentions, but other-oriented CDB is negatively associated. Findings reveal how altruism moderates this model.

Research limitations/implications

Findings show how personality traits influence CDB and reveal the relationship between CDB, as virtual conspicuous consumption on social media platforms, and donation behaviour.

Practical implications

The study provides implications for managers about enhancing charitable donations through social media.

Originality/value

This is the first study to explore donation behaviour as a form of conspicuous consumption on social media, where virtual conspicuous consumption (i) does not require any offline consumption and (ii) may achieve the desired recognition, without any charitable act. It provides new insights into CDB, its antecedents and influence on donation behaviour.

Details

European Journal of Marketing, vol. 51 no. 11/12
Type: Research Article
ISSN: 0309-0566

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Article
Publication date: 7 September 2012

Juliana Luísa Müller, Raphaël Romary, Abdelkader Benabou, Thomas Henneron, Francis Piriou, João Pedro Assumpção Bastos and Jean‐Yves Roger

Interlaminar short circuits in turbo generator stators can lead to local damage of the iron core. The purpose of this paper is to model an interlaminar short circuit diagnosis…

168

Abstract

Purpose

Interlaminar short circuits in turbo generator stators can lead to local damage of the iron core. The purpose of this paper is to model an interlaminar short circuit diagnosis test on an existing structure.

Design/methodology/approach

This work presents the modeling of short‐circuited laminations in a stator yoke of a turbo‐generator. A 3D finite element model, associated to a homogenization technique, is used to calculate the short‐circuit current. The diagnosis test known as El Cid has been modelled as well.

Findings

Calculation results are compared with the experiment. The same tendency has been observed both in experimental and numerical results.

Research limitations/implications

Additional calculations may be performed (parametric studies) in order to investigate El Cid measuring under different conditions (different material properties, fault position, size), which may lead to a better interpretation of the results.

Practical implications

Modelling of short circuit diagnosis tests under different conditions may help with the interpretation of measuring results, predicting the fault size/seriousness and location. So, only the concerned parts of the stator have to be disassembled and repaired/rebuilt.

Originality/value

It is not easy to model numerically a structure with a short circuit inside, since different dimensions are involved: the fault and the varnish between laminations are much smaller than the stator itself. Thus, homogenization techniques have been used to model the lamination stack region. The combination of this technique with the modelling of the El Cid test constitutes a tool to study this kind of fault and calculate its severity and location in a stator.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 31 no. 5
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 1 September 2004

J. Gyselinck, P. Dular, N. Sadowski, J. Leite and J.P.A. Bastos

This paper deals with the incorporation of a vector hysteresis model in 2D finite‐element (FE) magnetic field calculations. A previously proposed vector extension of the…

961

Abstract

This paper deals with the incorporation of a vector hysteresis model in 2D finite‐element (FE) magnetic field calculations. A previously proposed vector extension of the well‐known scalar Jiles‐Atherton model is considered. The vectorised hysteresis model is shown to have the same advantages as the scalar one: a limited number of parameters (which have the same value in both models) and ease of implementation. The classical magnetic vector potential FE formulation is adopted. Particular attention is paid to the resolution of the nonlinear equations by means of the Newton‐Raphson method. It is shown that the application of the latter method naturally leads to the use of the differential reluctivity tensor, i.e. the derivative of the magnetic field vector with respect to the magnetic induction vector. This second rank tensor can be straightforwardly calculated for the considered hysteresis model. By way of example, the vector Jiles‐Atherton is applied to two simple 2D FE models exhibiting rotational flux. The excellent convergence of the Newton‐Raphson method is demonstrated.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 23 no. 3
Type: Research Article
ISSN: 0332-1649

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Article
Publication date: 8 May 2009

Krzysztof Chwastek, Jan Szczygłowski and Wiesław Wilczyński

The aim of the paper is to present a simple approach to modelling minor hysteresis loops in grain‐oriented steel sheets under quasi‐static and dynamic conditions. The hysteresis…

730

Abstract

Purpose

The aim of the paper is to present a simple approach to modelling minor hysteresis loops in grain‐oriented steel sheets under quasi‐static and dynamic conditions. The hysteresis phenomenon is described with a recently developed hybrid model, which combines ideas inherent in the product Preisach model and the Jiles‐Atherton description. The dynamic effects due to eddy currents are taken into account in the description using a lagged response with respect to the input.

Design/methodology/approach

It is assumed that some model parameters might be dependent on the level of relative magnetization within the material. Their dependencies could be given as power laws. The values of scaling coefficients in power laws are determined.

Findings

A satisfactory agreement of experimental and modelled quasi‐static and dynamic hysteresis loops is obtained.

Research limitations/implications

The present study provides a starting point for further verification of the approach for other classes of soft magnetic materials, which could be described with the developed model. At present, the approach to model minor loops by the update of model parameters is verified for the B‐sine excitation case.

Practical implications

The “branch‐and‐bound” optimization algorithm is a useful tool for recovery of the values of both model parameters and scaling coefficients as well.

Originality/value

The recently developed hybrid description of hysteresis phenomenon can be successfully extended to take into account symmetric minor loops. The developed approach could be a framework to develop a comprehensive description of magnetization phenomena in the future.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 28 no. 3
Type: Research Article
ISSN: 0332-1649

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