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See detailCorner asymptotics of the magnetic potential in the eddy-current model
Dauge, Monique; Dular, Patrick ULiege; Krähenbühl, Laurent et al

in Mathematical Methods in the Applied Sciences (2014), 37(13), 19241955

In this paper, we describe the scalar magnetic potential in the vicinity of a corner of a conducting body embedded in a dielectric medium in a bidimensional setting. We make explicit the corner asymptotic ... [more ▼]

In this paper, we describe the scalar magnetic potential in the vicinity of a corner of a conducting body embedded in a dielectric medium in a bidimensional setting. We make explicit the corner asymptotic expansion for this potential as the distance to the corner goes to zero. This expansion involves singular functions and singular coefficients. We introduce a method for the calculation of the singular functions near the corner and we provide two methods to compute the singular coefficients: the method of moments and the method of quasi-dual singular functions. Estimates for the convergence of both approximate methods are proven. We eventually illustrate the theoretical results with finite element computations. The specific non-standard feature of this problem lies in the structure of its singular functions: They have the form of series whose first terms are harmonic polynomials and further terms are genuine non-smooth functions generated by the piecewise constant zeroth order term of the operator. [less ▲]

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See detailOptimizing the geometrical accuracy of 2D curvilinear finite element meshes
Remacle, Jean-François; Lambrechts, Jonathan; Toulorge, Thomas et al

Conference (2014, June 27)

Detailed reference viewed: 20 (5 ULiège)
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See detailDouble Sweep Preconditioners for propagation problems solved by Optimized Schwarz Methods
Vion, Alexandre ULiege; Geuzaine, Christophe ULiege

in Proceedings of the 6th International Conference on Advanced COmputational Methods in ENgineering, ACOMEN 2014 (2014, June)

Detailed reference viewed: 25 (7 ULiège)
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See detailComparison of implementation techniques for Galerkin projection between different meshes
Wang, Zifu; Henneron, Thomas; Dular, Patrick ULiege et al

in International Journal of Numerical Modeling: Electronic Networks, Devices and Fields (2014), 27(3), 517-526

To solve multiphysics problems, weak coupling of finite element calculations can be carried out: the subproblems of which the physical nature differs are solved separately on their own meshes. In this ... [more ▼]

To solve multiphysics problems, weak coupling of finite element calculations can be carried out: the subproblems of which the physical nature differs are solved separately on their own meshes. In this case, Galerkin projection provides useful tool to ensure the transfer of physical fields between different meshes. In terms of implementation, the Galerkin projection system can be either accurately assembled over the intersection of two meshes or approximately integrated over the target mesh. This paper describes and compares these two implementation techniques for the Galerkin projection. [less ▲]

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See detailAnalysis of transient scattering problems using a discontinuous Galerkin method: application to the shielding effectiveness of enclosures with heterogeneous walls
Boubekeur, Mohamed; Kameni, Abelin; Pichon, Lionel et al

in International Journal of Numerical Modelling: Electronic Networks, Devices and Fields (2014), 27(3), 626-635

In this paper, different formulations of Maxwell equations are combined for computing the shielding effectiveness of enclosures made from heterogeneous periodic materials. The validity of the homogenized ... [more ▼]

In this paper, different formulations of Maxwell equations are combined for computing the shielding effectiveness of enclosures made from heterogeneous periodic materials. The validity of the homogenized parameters given by Maxwell-Garnett rules in the frequency domain are tested in the time domain using a nodal discontinuous Galerkin method, which uses an interface condition based on analytical solution in the frequency domain to replace a conductive sheet. This interface condition allows to avoid meshing the thin sheet, thus reducing the computational cost. Results of scattering by composite enclosures are presented in the frequency domain thanks to a Fast Fourier Transform. [less ▲]

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See detailOptimized Waveform Relaxation Methods for Modeling Electromagnetic Field-Circuit Problems
Nshimiyimana, Jean de Dieu ULiege; Plumier, Frédéric ULiege; Dular, Patrick ULiege et al

in Proceedings of Sixteenth Biennal IEEE Conference on Electromagnetic Field Computation (2014, April)

The convergence of classical and optimized waveform relaxation methods is compared for the simulation of field-circuit problems, where a finite element solver is used for the solution of the field problem ... [more ▼]

The convergence of classical and optimized waveform relaxation methods is compared for the simulation of field-circuit problems, where a finite element solver is used for the solution of the field problem and a circuit simulator is used for the electronic circuit. [less ▲]

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See detailNonlinear Computational Homogenization Method for the Evaluation of Eddy Currents in Soft Magnetic Composites
Niyonzima, Innocent ULiege; Sabariego, Ruth Vazquez; Dular, Patrick ULiege et al

in IEEE Transactions on Magnetics (2014), 50(02),

In this paper, a heterogeneous multiscale method technique is applied to model the behavior of electromagnetic fields in soft magnetic composites (SMC). Two problems are derived from the two-scale ... [more ▼]

In this paper, a heterogeneous multiscale method technique is applied to model the behavior of electromagnetic fields in soft magnetic composites (SMC). Two problems are derived from the two-scale homogenization theory: a macroscale problem that captures the slow variations of the overall solution, and many mesoscale problems that allow determining the constitutive laws at the macroscale. As application, an SMC core is considered. [less ▲]

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See detailPerfect Conductor and Impedance Boundary Condition Corrections via a Finite Element Subproblem Method
Dular, Patrick ULiege; Péron, Victor; Perrussel, Ronan et al

in IEEE Transactions on Magnetics (2014), 50(2),

A finite element subproblem method is developed to correct the inaccuracies proper to perfect conductor and impedance boundary condition models, particularly near edges and corners of the conductors, for ... [more ▼]

A finite element subproblem method is developed to correct the inaccuracies proper to perfect conductor and impedance boundary condition models, particularly near edges and corners of the conductors, for a large range of conductivities and frequencies. Successive local corrections, supported by fine local meshes, can be obtained from each model to a more accurate one, allowing efficient extensions of their domains of validity. [less ▲]

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See detailRéseau Qualité des Laboratoires de l'ULg - Rapport d'activité Février 2014
Beauvois, Véronique ULiege; Dumont, Fabien ULiege; Hubert, Philippe ULiege et al

Diverse speeche and writing (2014)

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See detailModeling of Transformer Core Joints via a Subproblem FEM and a Homogenization Technique
Ferreira da Luz, Mauricio Valencia; Dular, Patrick ULiege; Vianei Leite, Jean et al

in IEEE Transactions on Magnetics (2014), 50(2),

A subproblem finite element method is developed for modeling the transformer core joints. It applies magnetostatic and magnetodynamic models on progressive geometries and different components of the ... [more ▼]

A subproblem finite element method is developed for modeling the transformer core joints. It applies magnetostatic and magnetodynamic models on progressive geometries and different components of the solution, supported by different meshes. It allows an efficient and robust analysis of magnetic circuits in any frequency range, with an accurate calculation of flux density, losses, reluctance, and impedance in transformer core joint zone. The models of the study properly account for the effects of core design parameters such as length of air gaps and overlap length in stacked-lamination cores. The proposed models, which include saturation, are applied to grain-oriented silicon steel and two types of step-lap joints are considered: single-step-lap (SSL) joints and multistep-lap (MSL) joints. The values of magnetic reluctance, impedance, and Joule losses obtained with SSL joint are bigger than with MSL joint. [less ▲]

Detailed reference viewed: 69 (2 ULiège)
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See detailComparison of Residual and Hierarchical Finite Element Error Estimators in Eddy Current Problems
Dular, Patrick ULiege; Tang, Zuqi; Le Ménach, Yvonnick et al

in IEEE Transactions on Magnetics (2014), 50(2),

The finite element computation of eddy current problems introduces numerical error. This error can only be estimated. Among all error estimators (EEs) already developed, two estimators, called residual ... [more ▼]

The finite element computation of eddy current problems introduces numerical error. This error can only be estimated. Among all error estimators (EEs) already developed, two estimators, called residual and hierarchical EEs, proven to be reliable and efficient, are theoretically and numerically compared. Both estimators show similar behaviors and locations of the error. [less ▲]

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See detailProgressive eddy current modeling via a finite element subproblem method
Dular, Patrick ULiege; Péron, Victor; Krähenbühl, Laurent et al

in International Journal of Applied Electromagnetics and Mechanics (2014), 46

The modeling of eddy currents in conductors is split into a sequence of progressive finite element subproblems. The source fields generated by the inductors alone are calculated at first via either the ... [more ▼]

The modeling of eddy currents in conductors is split into a sequence of progressive finite element subproblems. The source fields generated by the inductors alone are calculated at first via either the Biot-Savart law or finite elements. The associated reaction fields for each added conductive region, and in return for the source regions themselves when massive, are then calculated with finite element models, possibly with initial perfect conductor and/or impedance boundary conditions to be further corrected. The resulting subproblem method allows efficient solving of parameterized analyses thanks to a proper mesh for each subproblem and the reuse of previous solutions to be locally corrected. [less ▲]

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See detailShape Optimization of Interior Permanent Magnet Motor for Torque Ripple Reduction
Kuci, Erin ULiege; Geuzaine, Christophe ULiege; Dular, Patrick ULiege et al

in Proceedings of The 4th International Conference on Engineering Optimization: Lisbon (Portugal), 8-11 September 2014 (2014)

The objective of the paper is to present an open source environment to perform the design, simulation (Gmsh, GetDP) and optimization (OpenOpt) of electrical machines. The design of the permanent magnets ... [more ▼]

The objective of the paper is to present an open source environment to perform the design, simulation (Gmsh, GetDP) and optimization (OpenOpt) of electrical machines. The design of the permanent magnets of a v-shaped interior permanent magnet machine is then considered. The later is modeled using the finite element method with a formulation based on the magnetic vector potential. Optimization is based on mathematical programming approach. A semi-analytical sensitivity analysis is compared with the finite difference. Thanks to this approach, the design time is much shorter than that required by an approach of trial and error used by industry. The reduction of the torque ripple is about 70 \% with respect to the original design. [less ▲]

Detailed reference viewed: 193 (9 ULiège)
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See detailSpecial Issue: The 9th International Symposium on Electric and Magnetic Fields (EMF 2013)
Dupre, Luc; Geuzaine, Christophe ULiege

Book published by Wiley & Sons (2014)

Detailed reference viewed: 60 (5 ULiège)
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See detailEfficient finite element assembly of high order Whitney forms
Marsic, Nicolas ULiege; Geuzaine, Christophe ULiege

in IET Conference Proceedings (2014)

This paper presents an efficient method for the finite element assembly of high order Whitney elements. We start by reviewing the classical assembly technique and by highlighting the most time consuming ... [more ▼]

This paper presents an efficient method for the finite element assembly of high order Whitney elements. We start by reviewing the classical assembly technique and by highlighting the most time consuming part. Then, we show how this classical approach can be reformulated into a computationally efficient matrix - matrix product. We also address the problem of the basis orientation by considering more than one reference space. We conclude by presenting numerical results on a wave guide problem. [less ▲]

Detailed reference viewed: 53 (17 ULiège)
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See detailParallel Finite Element Assembly of High Order Whitney Forms
Marsic, Nicolas ULiege; Geuzaine, Christophe ULiege

Conference (2014)

This paper presents an efficient method for the finite element assembly of high order Whitney elements. We start by reviewing the classical assembly technique and by highlighting the most time consuming ... [more ▼]

This paper presents an efficient method for the finite element assembly of high order Whitney elements. We start by reviewing the classical assembly technique and by highlighting the most time consuming part. This classical approach can be reformulated into a computationally efficient matrix-matrix product. We conclude by presenting numerical results on a wave guide problem. [less ▲]

Detailed reference viewed: 16 (2 ULiège)
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See detailDouble sweep preconditioner for optimized Schwarz methods applied to the Helmholtz problem
Vion, Alexandre ULiege; Geuzaine, Christophe ULiege

in Journal of Computational Physics (2014), 266

Detailed reference viewed: 37 (10 ULiège)
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See detailParallel Finite Element Assembly of High Order Whitney Forms
Marsic, Nicolas ULiege; Geuzaine, Christophe ULiege

Conference (2014)

This paper presents an efficient method for the finite element assembly of high order Whitney elements. We start by highlighting the most time consuming parts of the classical assembly technique. This ... [more ▼]

This paper presents an efficient method for the finite element assembly of high order Whitney elements. We start by highlighting the most time consuming parts of the classical assembly technique. This approach can be reformulated into a computationally efficient matrix-matrix product. We conclude by presenting numerical results. [less ▲]

Detailed reference viewed: 15 (2 ULiège)