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1 – 10 of 27Salvatore Alfonzetti, Giuseppe Borzì and Nunzio Salerno
The purpose of this paper is to improve the accuracy of the integral equation of the hybrid FEM‐RBCI (Finite Element Method‐Robin Boundary Condition Iteration) method for the…
Abstract
Purpose
The purpose of this paper is to improve the accuracy of the integral equation of the hybrid FEM‐RBCI (Finite Element Method‐Robin Boundary Condition Iteration) method for the numerical solution of two‐dimensional electromagnetic (or acoustic) scattering problems.
Design/methodology/approach
This accuracy improvement is achieved by selecting the integration curve as straight segments lying in the middle of the triangular finite elements. An accuracy improvement is obtained as compared with selecting the integration curve as constituted by element sides.
Findings
The improved FEM‐RBCI method described in this paper leads to accuracies of the numerical results which are better than those obtained by selecting the integration curve by element sides.
Originality/value
The paper presents results for a simple two‐dimensional structure: a dielectric circular cylinder.
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Michael E. Roloff, Gaylen D. Paulson and Jennifer Vollbrecht
Social systems devise rules for member conduct and often specify punitive action for nonconformity. However, confronting and signaling the intent to punish a rule violator may be…
Abstract
Social systems devise rules for member conduct and often specify punitive action for nonconformity. However, confronting and signaling the intent to punish a rule violator may be an inherently face‐threatening and volatile situation. As such, in this paper we seek to add to the research aimed at minimizing the negative effects of confrontation. We conducted an experiment to examine the impact of linguistic cues and coercive potential on message categorization and on receiver perceptions of threat and face‐sensitivity. Results suggest that threats might be considered a special class of warnings, distinguishable by a speaker‐based locus of punishment Locus of punishment did not, however, impact perceptions of having been warned. These findings thus call into question the assumed parallelism between researcher conceptualizations of threats and warnings and those of typical language‐users. Additionally, targets reported feeling less threatened and perceived more face‐sensitivity, in cases when the speaker was not the source of punishment. Perceptions of threat were decreased when disclaimers were employed and where the message originated from a peer rather than an authority. Power of speech had an impact in ambiguous situations. Implications for researchers and practitioners are discussed.
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.
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Giovanni Aiello, Salvatore Alfonzetti, Giuseppe Borzì, Emanuele Dilettoso and Nunzio Salerno
This paper aims to extend an efficient method to solve the global system of linear algebraic equations in the hybrid finite element method – boundary element method (FEM‐BEM…
Abstract
Purpose
This paper aims to extend an efficient method to solve the global system of linear algebraic equations in the hybrid finite element method – boundary element method (FEM‐BEM) solution of open‐boundary skin effect problems. The extension covers the cases in which the skin effect problem is set in a truncated domain in which no homogeneous Dirichlet conditions are imposed.
Design/methodology/approach
The extended method is based on use of the generalized minimal residual (GMRES) solver, which is applied virtually to the reduced system of equations in which the unknowns are the nodal values of the normal derivative of the magnetic vector potential on the fictitious truncation boundary. In each step of the GMRES algorithm the FEM equations are solved by means of the standard complex conjugate gradient solver, whereas the BEM equations are not solved but used to perform fast matrix‐by‐vector multiplications. The BEM equations are written in a non‐conventional way, by making the nodes for the potential non‐coinciding with the nodes for its normal derivative.
Findings
The paper shows that the method proposed is very competitive with respect to other methods to solve open‐boundary skin effect problems.
Originality/value
The paper illustrates a new method to solve efficiently skin effect problems in open boundary domains by means of the hybrid FEM‐BEM method.
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S. Alfonzetti, G. Borzì and N. Salerno
The Robin iteration procedure is a technique for the FEM computation of electromagnetic scattering fields in unbounded domains. It is based on the iterative improvement of the…
Abstract
The Robin iteration procedure is a technique for the FEM computation of electromagnetic scattering fields in unbounded domains. It is based on the iterative improvement of the known term of a non‐homogeneous Robin condition on a fictitious boundary enclosing the scatterer. In this paper it is shown that the procedure is equivalent to the application of the Richardson method to a reduced system and that the use of GMRES significantly reduces the computational effort.
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Mohammed Ali Al Mallak, Lin Mei Tan and Fawzi Laswad
The purpose of this exploratory study is to examine the perceptions of Saudi university accounting students of the importance of developing generic skills in their accounting…
Abstract
Purpose
The purpose of this exploratory study is to examine the perceptions of Saudi university accounting students of the importance of developing generic skills in their accounting education, the levels of competence they should acquire and expect to achieve during the academic study, and the constraints that may hinder the development of generic skills in accounting education.
Design/methodology/approach
The study uses the skills outlined in the IFAC’s International Education Standards (IES) 3 (intellectual, personal, organizational and business management, and interpersonal and communication) and IES 4 (ethics in accounting/business). A survey questionnaire was used to collect the data.
Findings
The findings show that students perceived all five generic skill categories to be important, with ethical skills rated as the most important. However, the students expected that they would achieve a somewhat lower level of generic skill by the end of their studies in all areas, and they perceived a number of constraints that impede their skill development. The results indicate the importance of developing generic skills in accounting education and suggest that the Saudi accounting education system could do more to provide students with opportunities to develop generic skills to enable them to succeed in their future careers.
Originality/value
As little of the current literature has focused on generic skills in accounting education in a non-Western country, this research contributes to the literature on generic skills in a developing nation.
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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 open-boundary skin…
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.
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Giovanni Aiello, Salvatore Alfonzetti, Santi Agatino Rizzo and Nunzio Salerno
The optimization of the cross section of an axisymmetric induction heating device is performed by means of genetic algorithms (GAs).
Abstract
Purpose
The optimization of the cross section of an axisymmetric induction heating device is performed by means of genetic algorithms (GAs).
Design/methodology/approach
The hybrid finite element method–Dirichlet boundary condition iteration method is used to deal with the unbounded nature of the field. The formulation of the electromagnetic problems takes into account skin and proximity effects in the source currents.
Findings
The convergence of GAs towards the optimum is very fast, since less than a thousand analyses have been necessary.
Originality/value
A special derivation of the finite element global system is presented which allows us to save computing time.
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S. Alfonzetti, G. Aiello, E. Dilettoso and N. Salerno
This paper aims to discuss various numerical implementations of the integral equation in the hybrid finite element method‐Dirichlet boundary condition iteration (FEM‐DBCI) method…
Abstract
Purpose
This paper aims to discuss various numerical implementations of the integral equation in the hybrid finite element method‐Dirichlet boundary condition iteration (FEM‐DBCI) method for the numerical solution of unbounded static and quasi‐static electromagnetic field problems.
Design/methodology/approach
Three numerical implementations are described and compared from the point of view of accuracy and complexity, by means of two examples regarding simple electrostatic problems.
Findings
The implementation by means of a pair of integration surfaces made of element sides leads to accuracy levels which are much better than that of a single surface (made of element sides) and only a little worse than that of a single surface connecting point in the middle of finite element sides.
Practical implications
The former implementations, however, are simpler since they are practically the same as that of a standard boundary element method integral equation.
Originality/value
The paper constitutes a useful guide to the implementation of the FEM‐DBCI method.
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G. Aiello, S. Alfonzetti, E. Dilettoso and N. Salerno
This paper aims to propose a hybrid method, called finite element method‐Dirichlet boundary condition iteration (FEM‐DBCI), for the computation of time‐harmonic eddy current…
Abstract
Purpose
This paper aims to propose a hybrid method, called finite element method‐Dirichlet boundary condition iteration (FEM‐DBCI), for the computation of time‐harmonic eddy current problems inside a conductor heated by coils in 3D open‐boundary geometry.
Design/methodology/approach
The method assumes the electrical field as unknown on a mesh of tetrahedral edge elements. The heating power density inside the conductor is then computed and a steady‐state thermal analysis is performed on the same mesh of nodal tetrahedra to calculate the temperature distribution inside the heated piece, taking radiation and convection into account. A numerical example is also provided.
Findings
The method couples a differential equation for the interior problem in terms of the electric fields with an integral equation for the exterior one. The global algebraic system is efficiently solved in an iterative way.
Originality/value
The paper illustrates the computation of time‐harmonic eddy current problems inside a conductor heated by coils.
Details