Search results

1 – 10 of over 3000
To view the access options for this content please click here
Article
Publication date: 11 November 2013

Giovanni Aiello, Salvatore Alfonzetti, Giuseppe Borzì, Santi Agatino Rizzo and Nunzio Salerno

– The purpose of this paper is to compare the hybrid FEM-BEM and FEM-DBCI methods for the solution of open-boundary static and quasi-static electromagnetic field problems.

Abstract

Purpose

The purpose of this paper is to compare the hybrid FEM-BEM and FEM-DBCI methods for the solution of open-boundary static and quasi-static electromagnetic field problems.

Design/methodology/approach

After a brief review of the two methods (both coupling a differential equation for the interior problem with an integral equation for the exterior one), they are compared in terms of accuracy, memory and computing time requirements by means of a set of simple examples.

Findings

The comparison suggests that FEM-BEM is more accurate than FEM-DBCI but requires more computing time.

Practical implications

Then FEM-DBCI appears more appropriate for applications which require a shorter computing time, for example in the stochastic optimization of electromagnetic devices. Conversely, FEM-BEM is more appropriate in cases in which a high level of precision is required in a single computation.

Originality/value

Note that the FEM-BEM considered in this paper is a non standard one in which the nodes of the normal derivative on the truncation boundary are placed in positions different from those of the potential.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 32 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

To view the access options for this content please click here
Article
Publication date: 27 October 2020

Michael Minkov and Anneli Kaasa

Recent studies exposed serious issues with Hofstede's popular model of culture, especially his uncertainty avoidance (UA) and masculinity-femininity (MAS–FEM) dimensions…

Abstract

Purpose

Recent studies exposed serious issues with Hofstede's popular model of culture, especially his uncertainty avoidance (UA) and masculinity-femininity (MAS–FEM) dimensions. However those studies did not focus on work-related issues as in Hofstede’s research.

Design/methodology/approach

We followed Hofstede’s approach to his dimensions more closely than anyone before in a large cross-cultural study. We used data from the nationally representative International Social Survey Program (over 50,000 respondents from 47 countries), measuring work goals and work-related stress in a way similar to Hofstede's.

Findings

UA and MAS–FEM, as measured and described by Hofstede, did not replicate. They lack internal consistency and the items that target them are not associated with Hofstede's UA and MAS–FEM indices. Instead, some of those items follow a very different and sound logic, invalidating Hofstede's UA and MAS–FEM theories. Our study provides additional evidence that UA and MAS–FEM are misleading artifacts of Hofstede's IBM database, with no analogues outside IBM. An improved, recently reported version of individualism-collectivism (IDV-COLL) replicated nearly perfectly, solidifying the validity of that dimension of national culture. A revised version of long-term orientation, called flexibility–monumentalism (FLX–MON) also replicated well.

Research limitations/implications

We discuss lessons for the cross-cultural field, including cross-cultural management, as well as policy-making by national governments, to be drawn from the controversial story of Hofstede's model. We advise a stronger focus on empirical confirmation and replication rather than excessive faith in fascinating, yet unproven theory.

Practical implications

To avoid further confusion, we advise researchers, consultants and managers to reconsider the use of Hofstede's UA and MAS–FEM and focus on the valid dimensions in the revised Minkov-Hofstede model.

Social implications

A number of national governments recently launched large-scale studies of their national cultures, based on Hofstede's model. The goal of those studies was to involve culture in the design of social and economic development policies. Studies of this kind should be founded on empirically sound models or else they can result in the formulation of flawed policies.

Originality/value

This is the first study of large samples from many nations showing that even when Hofstede's method is followed closely by focusing on work-related issues, UA and MAS–FEM do not emerge from the data, and this is not because of data deficiencies but because the logic of UA and MAS–FEM is demonstrably flawed. Our study also demonstrates new methods for the replication of IDV-COLL and FLX–MON, though without claiming that they are superior to existing ones.

To view the access options for this content please click here
Article
Publication date: 16 March 2020

Muhamad Husnain Mohd Noh, Mohd Akramin Mohd Romlay, Chuan Zun Liang, Mohd Shamil Shaari and Akiyuki Takahashi

Failure of the materials occurs once the stress intensity factor (SIF) overtakes the material fracture toughness. At this level, the crack will grow rapidly resulting in…

Abstract

Purpose

Failure of the materials occurs once the stress intensity factor (SIF) overtakes the material fracture toughness. At this level, the crack will grow rapidly resulting in unstable crack growth until a complete fracture happens. The SIF calculation of the materials can be conducted by experimental, theoretical and numerical techniques. Prediction of SIF is crucial to ensure safety life from the material failure. The aim of the simulation study is to evaluate the accuracy of SIF prediction using finite element analysis.

Design/methodology/approach

The bootstrap resampling method is employed in S-version finite element model (S-FEM) to generate the random variables in this simulation analysis. The SIF analysis studies are promoted by bootstrap S-version Finite Element Model (BootstrapS-FEM). Virtual crack closure-integral method (VCCM) is an important concept to compute the energy release rate and SIF. The semielliptical crack shape is applied with different crack shape aspect ratio in this simulation analysis. The BootstrapS-FEM produces the prediction of SIFs for tension model.

Findings

The mean of BootstrapS-FEM is calculated from 100 samples by the resampling method. The bounds are computed based on the lower and upper bounds of the hundred samples of BootstrapS-FEM. The prediction of SIFs is validated with Newman–Raju solution and deterministic S-FEM within 95 percent confidence bounds. All possible values of SIF estimation by BootstrapS-FEM are plotted in a graph. The mean of the BootstrapS-FEM is referred to as point estimation. The Newman–Raju solution and deterministic S-FEM values are within the 95 percent confidence bounds. Thus, the BootstrapS-FEM is considered valid for the prediction with less than 6 percent of percentage error.

Originality/value

The bootstrap resampling method is employed in S-FEM to generate the random variables in this simulation analysis.

Details

International Journal of Structural Integrity, vol. 11 no. 4
Type: Research Article
ISSN: 1757-9864

Keywords

To view the access options for this content please click here
Article
Publication date: 16 November 2010

Francisc Bölöni, Abdelkader Benabou and Abdelmounaïm Tounzi

Electrostatic microelectromechanical systems are characterized by the pull‐in instability, associated to a pull‐in voltage. A good design requires an accurate model of…

Abstract

Purpose

Electrostatic microelectromechanical systems are characterized by the pull‐in instability, associated to a pull‐in voltage. A good design requires an accurate model of this pull‐in phenomenon. The purpose of this paper is to present two approaches to building finite element method (FEM) based models.

Design/methodology/approach

Closed form expressions for the computation of the pull‐in voltage, can provide fast results within reliable accuracy, except when treating cases of extreme fringing fields. FEM‐based models come handy when high accuracy is needed. In the first model presented in this paper, the FEM is used to solve the electrostatic problem, while the mechanical problem is solved using a simplified Euler‐Bernoulli beam equation. The second model is a pure FEM model coupling the electrostatic and mechanical problems iteratively through the electrical force. Results for both scalar and vector potential formulations for the FEM models are presented.

Findings

In this paper a comparative study of simple pull‐in structures is presented, between analytical and 3D FEM‐based models. A comparison with analytical models and experimental results is also realized.

Research limitations/implications

The coupling between the electrostatic and mechanical problem in the presented approaches, is iterative. Therefore, to improve the accuracy of the presented model, a strong coupling is needed.

Originality/value

In the presented FEM‐analytical model, the electrostatic problem is solved in both, scalar and vector electric potential formulations. This allows defining an upper and a lower limit for the electrostatic force and consequently for the pull‐in voltage.

Details

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

Keywords

To view the access options for this content please click here
Article
Publication date: 17 August 2012

G.S. Aglietti, S.J.I. Walker and A. Kiley

The purpose of this paper is to assess the suitability of various methods for the reduction of a large finite element model (FEM) of satellites to produce models to be…

Abstract

Purpose

The purpose of this paper is to assess the suitability of various methods for the reduction of a large finite element model (FEM) of satellites to produce models to be used for correlation of the FEM with test results. The robustness of the cross‐orthogonality checks (COC) for the correlation process carried out utilizing the reduced model is investigated, showing its dependence on the number of mode shapes used in the reduction process. Finally the paper investigates the improvement in the robustness of the COC that can be achieved utilizing optimality criteria for the selection of the degrees of freedom (DOF) used for the correlation process.

Design/methodology/approach

A Monte Carlo approach has been used to simulate inaccuracies in the mode shapes (analysis and experimental) of a satellite FEM that are compared during the COC. The sensitivity of the COC to the parameters utilized during the reduction process, i.e. mode shapes and DOFs, is then assessed for different levels of inaccuracy in the mode shapes.

Findings

The System Equivalent Expansion Reduction Process (SEREP) has been identified as a particularly suitable method, with the advantage that a SEREP reduced model has the same eigenvalues and eigenvector of the whole system therefore automatically meeting the criteria on the quality of the reduced model. The inclusion of a high number of mode shapes in the reduction process makes the check very sensitive to minor experimental or modelling inaccuracies. Finally it was shown that utilizing optimality criteria in the selection of the DOFs to carry out the correlation can significantly improve the probability of meeting the COC criteria.

Research limitations/implications

This work is based on the FEM of the satellite Aeolus, and therefore the numerical values obtained in this study are specific for this application. However, this model represents a typical satellite FEM and therefore the trends identified in this work are expected to be generally valid for this type of structure.

Practical implications

The correlation of satellite FEM with test results involves a substantial effort, and it is crucial to avoid failures of the COC due to numerical issues rather than real model inaccuracies. This work shows also how an inappropriate choice of reduction parameters can lead to failure of the COC in cases when there are only very minor differences (e.g. due to minor amount of noise in the results) between analytical and test results. Vice versa, the work also shows how the robustness of the reduced model can be improved.

Originality/value

The paper shows how the robustness of the correlation process for a satellite FEM carried out utilising a SEREP reduced model needed to be investigated, to demonstrate the suitability of this method to reduce large FEM of satellites.

To view the access options for this content please click here
Article
Publication date: 28 October 2014

Giovanni Aiello, Salvatore Alfonzetti and Nunzio Salerno

The purpose of this paper is to present a modified version of the hybrid Finite Element Method-Dirichlet Boundary Condition Iteration method for the solution of…

Abstract

Purpose

The purpose of this paper is to present a modified version of the hybrid Finite Element Method-Dirichlet Boundary Condition Iteration method for the solution of open-boundary skin effect problems.

Design/methodology/approach

The modification consists of overlapping the truncation and the integration boundaries of the standard method, so that the integral equation becomes singular as in the well-known Finite Element Method-Boundary Element Method (FEM-BEM) method. The new method is called FEM-SDBCI. Assuming an unknown Dirichlet condition on the truncation boundary, the global algebraic system is constituted by the sparse FEM equations and by the dense integral equations, in which singularities arise. Analytical formulas are provided to compute these singular integrals. The global system is solved by means of a Generalized Minimal Residual iterative procedure.

Findings

The proposed method leads to slightly less accurate numerical results than FEM-BEM, but the latter requires much more computing time.

Practical implications

Then FEM-SDBCI appears more appropriate than FEM-BEM for applications which require a shorter computing time, for example in the stochastic optimization of electromagnetic devices.

Originality/value

Note that FEM-SDBCI assumes a Dirichlet condition on the truncation boundary, whereas FEM-BEM assumes a Neumann one.

Details

COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, vol. 33 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

To view the access options for this content please click here
Article
Publication date: 6 July 2015

Amir R. Khoei, R. Yasbolaghi and S.O.R. Biabanaki

In this paper, the polygonal-FEM technique is presented in modeling large deformation – large sliding contact on non-conformal meshes. The purpose of this paper is to…

Abstract

Purpose

In this paper, the polygonal-FEM technique is presented in modeling large deformation – large sliding contact on non-conformal meshes. The purpose of this paper is to present a new technique in modeling arbitrary interfaces and discontinuities for non-linear contact problems by capturing discontinuous deformations in elements cut by the contact surface in uniform non-conformal meshes.

Design/methodology/approach

The geometry of contact surface is used to produce various polygonal elements at the intersection of the interface with the regular FE mesh, in which the extra degrees-of-freedom are defined along the interface. The contact constraints are imposed between polygonal elements produced along the contact surface through the node-to-surface contact algorithm.

Findings

Numerical convergence analysis is carried out to study the convergence rate for various polygonal interpolation functions, including the Wachspress interpolation functions, the metric shape functions, the natural neighbor-based shape functions, and the mean value shape functions. Finally, numerical examples are solved to demonstrate the efficiency of proposed technique in modeling contact problems in large deformations.

Originality/value

A new technique is presented based on the polygonal-FEM technique in modeling arbitrary interfaces and discontinuities for non-linear contact problems by capturing discontinuous deformations in elements cut by the contact surface in uniform non-conformal meshes.

Details

Engineering Computations, vol. 32 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

To view the access options for this content please click here
Article
Publication date: 1 September 2017

Michael Minkov

Hofstede’s model of national culture has enjoyed enormous popularity but rests partly on faith. It has never been fully replicated and its predictive properties have been…

Abstract

Purpose

Hofstede’s model of national culture has enjoyed enormous popularity but rests partly on faith. It has never been fully replicated and its predictive properties have been challenged. The purpose of this paper is to provide a test of the model’s coherence and utility.

Design/methodology/approach

Analyses of secondary data, including the World Values Survey, and a new survey across 56 countries represented by nearly 53,000 probabilistically selected respondents.

Findings

Improved operationalizations of individualism-collectivism (IDV-COLL) suggest it is a robust dimension of national culture. A modern IDV-COLL index supersedes Hofstede’s 50 year-old original one. Power distance (PD) seems to be a logical facet of IDV-COLL, rather than an independent dimension. Uncertainty avoidance (UA) lacks internal reliability. Approval of restrictive societal rules and laws is a facet of COLL and is not associated with national anxiety or neuroticism. UA is not a predictor of any of its presumed main correlates: importance of job security, preference for a safe job, trust, racism and xenophobia, subjective well-being, innovation, and economic freedom. The dimension of masculinity-femininity (MAS-FEM) lacks coherence. MAS and FEM job goals and broader values are correlated positively, not negatively, and are not related to the MAS-FEM index. MAS-FEM is not a predictor of any of its presumed main correlates: achievement and competition orientation, help and compassion, preference for a workplace with likeable people, work orientation, religiousness, gender egalitarianism, foreign aid. After a radical reconceptualization and a new operationalization, the so-called “fifth dimension” (CWD or long-term orientation) becomes more coherent and useful. The new version, called flexibility-monumentalism (FLX-MON), explains the cultural differences between East Asian Confucian societies at one extreme and Latin America plus Africa at the other, and is the best predictor of national differences in educational achievement.

Research limitations/implications

Differences between subsidiaries of a multinational company, such as IBM around 1970, are not necessarily a good source of knowledge about broad cultural differences. A model of national culture must be validated across a large number of countries from all continents and its predictions should withstand various plausible controls. Much of Hofstede’s model (UA, MAS-FEM) fails this test while the remaining part (IDV-COLL, PD, LTO) needs a serious revision.

Practical implications

Consultancies and business schools still teach Hofstede’s model uncritically. They need to be aware of its deficiencies.

Originality/value

As UA and MAS-FEM are apparently misleading artifacts of Hofstede’s IBM data set, a thorough revision of Hofstede’s model is proposed, reducing it to two dimensions: IDV-COLL and FLX-MON.

Details

Cross Cultural & Strategic Management, vol. 25 no. 2
Type: Research Article
ISSN: 2059-5794

Keywords

To view the access options for this content please click here
Article
Publication date: 4 September 2017

Lars Kielhorn, Thomas Rüberg and Jürgen Zechner

Electrical machines commonly consist of moving and stationary parts. The field simulation of such devices can be demanding if the underlying numerical scheme is solely…

Abstract

Purpose

Electrical machines commonly consist of moving and stationary parts. The field simulation of such devices can be demanding if the underlying numerical scheme is solely based on a domain discretization, such as in the case of the finite element method (FEM). This paper aims to present a coupling scheme based on FEM together with boundary element methods (BEMs) that neither hinges on re-meshing techniques nor deals with a special treatment of sliding interfaces. While the numerics are certainly more involved, the reward is obvious: the modeling costs decrease and the application engineer is provided with an easy-to-use, versatile and accurate simulation tool.

Design/methodology/approach

The authors present the implementation of a FEM-BEM coupling scheme in which the unbounded air region is handled by the BEM, while only the solid parts are discretized by the FEM. The BEM is a convenient tool to tackle unbounded exterior domains, as it is based on the discretization of boundary integral equations (BIEs) that are defined only on the surface of the computational domain. Hence, no meshing is required for the air region. Further, the BIEs fulfill the decay and radiation conditions of the electromagnetic fields such that no additional modeling errors occur.

Findings

This work presents an implementation of a FEM-BEM coupling scheme for electromagnetic field simulations. The coupling eliminates problems that are inherent to a pure FEM approach. In detail, the benefits of the FEM-BEM scheme are: the decay conditions are fulfilled exactly, no meshing of parts of the exterior air region is necessary and, most importantly, the handling of moving parts is incorporated in an intriguingly simple manner. The FEM-BEM formulation in conjunction with a state-of-the-art preconditioner demonstrates its potency. The numerical tests not only reveal an accurate convergence behavior but also prove the algorithm to be suitable for industrial applications.

Originality/value

The presented FEM-BEM scheme is a mathematically sound and robust implementation of a theoretical work presented a decade ago. For the application within an industrial context, the original work has been extended by higher-order schemes, periodic boundary conditions and an efficient treatment of moving parts. While not intended to be used under all circumstances, it represents a powerful tool in case that high accuracies together with simple mesh-handling facilities are required.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 36 no. 5
Type: Research Article
ISSN: 0332-1649

Keywords

To view the access options for this content please click here
Article
Publication date: 6 July 2015

Guanxin Huang, Hu Wang and Guangyao Li

– The purpose of this paper is to enhance the feasibility of the edge-based smoothed triangular (EST) element, some modifications are made in this study.

Abstract

Purpose

The purpose of this paper is to enhance the feasibility of the edge-based smoothed triangular (EST) element, some modifications are made in this study.

Design/methodology/approach

First, an efficient strategy based on graph theory is proposed to construct the edge system. Second, the stress is smoothed in global coordinate system based on edge instead of strain, which makes the theory of EST more rigorous and can be easily extended to the situation of multi elements sharing the same edge. Third, the singular degree of freedoms (DOFs) of the nodes linked by edges are restrained in edge local coordinate system, which makes the global stiffness matrix non-singular and can be decomposed successfully.

Findings

First, an efficient edge constructing strategy can make EST element more standout. Second, some modifications should be made to EST element to extend it to the situation with multi elements sharing the same edge, so that EST element can deal with the geometrical models with this kind of features. Third, the way to restrain the singular DOFs of EST element must be different from normal isoparametric triangle element, because the stiffness matrix of the smoothing domain is not computed in local coordinate system.

Originality/value

The modified EST element performs stably in engineering analysis including large scale problems and the situation with multi elements sharing the same edge, and the efficiency of edge system constructing is no longer the bottleneck.

Details

Engineering Computations, vol. 32 no. 5
Type: Research Article
ISSN: 0264-4401

Keywords

1 – 10 of over 3000