Time-Domain Surface Impedance Boundary Conditions Enhanced by Coarse Volume Finite-Element Discretisation V Sabariego, Ruth ; Geuzaine, Christophe ; Dular, Patrick et al (2011) The time-domain surface impedance boundary conditions allow to accurately account for the high-frequency flux components while removing the massive conducting regions from the computation domain. In this ... [more ▼] The time-domain surface impedance boundary conditions allow to accurately account for the high-frequency flux components while removing the massive conducting regions from the computation domain. In this paper, a coarse volume finite-element discretization of the conductors together with a fictitious frequency-dependent conductivity are added to capture the slow varying flux components. This hybrid approach extends thus the frequency range of these impedance conditions. A 2-D test case illustrates the method. [less ▲] Detailed reference viewed: 30 (1 ULg)Considering Laminated Cores and Eddy Currents in 2D and 3D Finite Element Simulation of Electrical Machines ; Geuzaine, Christophe ; V Sabariego, Ruth (2011) This paper deals with a time-domain homogeniza- tion method for laminated cores and its application to the 2D finite element simulation of rotating electrical machines. The number of additional degrees of ... [more ▼] This paper deals with a time-domain homogeniza- tion method for laminated cores and its application to the 2D finite element simulation of rotating electrical machines. The number of additional degrees of freedom of the model, for considering the variation of the flux density along the lamination thickness, can be tuned so as to reach a good compromise between accuracy and computation time. The results obtained for a switched reluctance motor agree very well with those produced by a precise full 3D model in which eddy currents are explicitly modeled. [less ▲] Detailed reference viewed: 245 (3 ULg)High Quality Surface Remeshing Using Harmonic Maps. Part II: Surfaces with High Genus and of Large Aspect Ratio ; ; et al in International Journal for Numerical Methods in Engineering (2011), 86(11), 1303-1321 Detailed reference viewed: 37 (1 ULg)Quasi-Optimal Convergence of Non Overlapping Domain Decomposition Method: the Helmholtz Equation ; ; Geuzaine, Christophe in Proceedings of the AMS 2010 Fall Central Section Meeting (2010, November) Detailed reference viewed: 30 (2 ULg)High Quality Surface Remeshing Using Harmonic Maps: Surfaces with High Genus and of Large Aspect Ratio ; Geuzaine, Christophe ; in Proceedings of the Third Workshop on Grid Generation for Numerical Computations, Tetrahedron III (2010, September) Detailed reference viewed: 32 (1 ULg)An Amplitude Finite Element Formulation for Multiple-Scattering by a Collection of Convex Obstacles Geuzaine, Christophe ; Vion, Alexandre ; Gaignaire, Roman et al in IEEE Transactions on Magnetics (2010), 46(8), 2963-2966 We present a multiple-scattering solver for nonconvex geometries obtained as the union of a finite number of convex obstacles. The algorithm is a finite element reformulation of a high-frequency integral ... [more ▼] We present a multiple-scattering solver for nonconvex geometries obtained as the union of a finite number of convex obstacles. The algorithm is a finite element reformulation of a high-frequency integral equation technique proposed previously. It is based on an iterative solution of the scattering problem, where each iteration leads to the resolution of a single scattering problem in terms of a slowly oscillatory amplitude. [less ▲] Detailed reference viewed: 86 (21 ULg)Finite Element Magnetic Models via a Coupling of Subproblems of Lower Dimensions Dular, Patrick ; V Sabariego, Ruth ; Geuzaine, Christophe et al in IEEE Transactions on Magnetics (2010), 46(8), 2827-2830 Model refinements of magnetic circuits are performed via a subdomain finite element method based on a perturbation technique. A complete problem is split into subproblems, some of lower dimensions, to ... [more ▼] Model refinements of magnetic circuits are performed via a subdomain finite element method based on a perturbation technique. A complete problem is split into subproblems, some of lower dimensions, to allow a progression from 1-D to 3-D models. Its solution is then expressed as the sum of the subproblem solutions supported by different meshes. A convenient and robust correction procedure is proposed allowing independent overlapping meshes for both source and reaction fields, the latter being free of cancellation error in magnetic materials. The procedure simplifies both meshing and solving processes, and quantifies the gain given by each model refinement on both local fields and global quantities. [less ▲] Detailed reference viewed: 50 (6 ULg)Stochastic Uncertainty Quantification of the Conductivity in EEG Source Analysis by Using Polynomial Chaos Decomposition Gaignaire, Roman ; ; et al in IEEE Transactions on Magnetics (2010), 46(8), 3457-3460 The electroencephalogram (EEG) is one of the techniques used for the non-invasive diagnosis of patients suffering from epilepsy. EEG source localization identifies the neural activity, starting from ... [more ▼] The electroencephalogram (EEG) is one of the techniques used for the non-invasive diagnosis of patients suffering from epilepsy. EEG source localization identifies the neural activity, starting from measured EEG. This numerical localization procedure has a resolution, which is difficult to determine due to uncertainties in the EEG forward models. More specifically, the conductivities of the brain and the skull in the head models are not precisely known. In this paper, we propose the use of a non-intrusive stochastic method based on a polynomial chaos decomposition for quantifying the possible errors introduced by the uncertain conductivities of the head tissues. The accuracy and computational advantages of this non-intrusive method for EEG source analysis is illustrated. Further, the method is validated by means of Monte Carlo simulations. [less ▲] Detailed reference viewed: 71 (12 ULg)Surface-Impedance Boundary Conditions in Dual Time-Domain Finite-Element Formulations V Sabariego, Ruth ; Dular, Patrick ; Geuzaine, Christophe et al in IEEE Transactions on Magnetics (2010), 46(8), 3524-3531 This paper deals with time-domain surface-impedance boundary conditions in computational magnetodynamics considering two dual finite-element formulations and a nonlinear magnetic constitutive law. Based ... [more ▼] This paper deals with time-domain surface-impedance boundary conditions in computational magnetodynamics considering two dual finite-element formulations and a nonlinear magnetic constitutive law. Based on the resolution of the 1-D eddy-current problem in a semi-infinite slab, the massive conducting region is accounted for by choosing a number of exponentially decreasing trigonometric basis functions covering the relevant frequency range of the application in hand. Herein the method is elaborated for the magnetic-vector- potential formulation and the magnetic-field formulation. Results for both formulations are compared and validated on 2-D linear and nonlinear test cases. [less ▲] Detailed reference viewed: 98 (14 ULg)Toward Convergent Methods for High-Frequency Wave Problems Geuzaine, Christophe Scientific conference (2010, July 15) Detailed reference viewed: 15 (7 ULg)High-quality remeshing using harmonic maps Geuzaine, Christophe ; ; in Proceedings of the 5th Advanced Computational Electromagnetics workshop (2010, July) Detailed reference viewed: 10 (1 ULg)GetDP et Gmsh Geuzaine, Christophe Scientific conference (2010, June 16) Detailed reference viewed: 69 (6 ULg)High Quality Surface Meshing using Harmonic Maps Geuzaine, Christophe Scientific conference (2010, June 09) Detailed reference viewed: 14 (1 ULg)Non-linear magnetic model refinement via a finite element subproblem method Dular, Patrick ; V Sabariego, Ruth ; et al in Proceedings of the XXI Symposium on Electromagnetic Phenomena in Nonlinear Circuits (EPNC 2010) (2010, June) Model refinements of non-linear magnetic circuits are performed via a finite element subproblem method. A complete problem is split into subproblems to allow a progression from 1- D to 3-D including ... [more ▼] Model refinements of non-linear magnetic circuits are performed via a finite element subproblem method. A complete problem is split into subproblems to allow a progression from 1- D to 3-D including linear to non-linear model corrections. Its solution is then expressed as the sum of the subproblem solutions supported by different meshes. A convenient and robust correction procedure is proposed allowing independent overlapping meshes for both source and reaction fields. The procedure simplifies both meshing and solving processes, and quantifies the gain given by each model refinement on both local fields and global quantities. [less ▲] Detailed reference viewed: 24 (1 ULg)Modeling high-temperature superconductors containing an array of holes Vanderheyden, Benoît ; ; Ausloos, Marcel et al Conference (2010, May 07) We have recently implemented a finite-element model for the penetration of the magnetic flux inside a bulk superconductor containing an array of holes (thin-wall superconductor), with the help of the open ... [more ▼] We have recently implemented a finite-element model for the penetration of the magnetic flux inside a bulk superconductor containing an array of holes (thin-wall superconductor), with the help of the open-source code GetDp. In this talk, I introduce the A-phi formulation used, with edge elements and spanning tree gauges. I explain how a time-iterative method allows one to make calculations with fewer time steps, and compare the obtained results with those derived by the Brandt method. [less ▲] Detailed reference viewed: 11 (2 ULg)Passive ACS of Delphi-C3 nanosatellite ; ; Geuzaine, Christophe in Proceedings of the URSI Forum 2010 (2010, May) Detailed reference viewed: 22 (1 ULg)Analyzing and Reducing Error in 2-D Frequency Domain Homogenization of Windings for R, L Parameters FE Computation ; ; et al in Proceedings of the 14th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC2010) (2010, May) In this work, the error made by frequency domain homogenization of windings in 2-D magnetodynamics is quantified. To that end, the homogenized fields are combined with the analytical solutions (a) of eddy ... [more ▼] In this work, the error made by frequency domain homogenization of windings in 2-D magnetodynamics is quantified. To that end, the homogenized fields are combined with the analytical solutions (a) of eddy currents flowing in a circular conductor placed in a uniform alternating magnetic induction (proximity effect) and (b) of current density in conductors with non-zero net current (skin effect). They are then compared to the fields from the fine model, taken as reference. It is shown that error on resistance can reach 10\% at high frequencies for magnetic components with a limited number of turns. Procedures to improve winding R, L parameters estimation from homogenized solution are introduced. [less ▲] Detailed reference viewed: 28 (9 ULg)Correction of Thin Shell Finite Element Magnetic Models via a Subproblem Method Dular, Patrick ; Dang, Quoc Vuong ; V Sabariego, Ruth et al in Proceedings of the 14th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC2010) (2010, May) A sub-problem finite element method is developed for correcting the inaccuracies near edges and corners inherent to thin shell models, for both magnetostatic and magnetodynamic problems. A thin shell ... [more ▼] A sub-problem finite element method is developed for correcting the inaccuracies near edges and corners inherent to thin shell models, for both magnetostatic and magnetodynamic problems. A thin shell solution, supported by a simplified mesh near the thin structures, serves as a source of a correction problem with the actual volumic thin regions alone in a homogeneous medium, concentrating the meshing effort on the thin regions only. Improvements of local fields are efficiently achieved and allow accurate force and loss calculations. [less ▲] Detailed reference viewed: 64 (32 ULg)Combining Surface Impedance Boundary Conditions with Volume Discretisation in Time-Domain Finite-Element Modeling ; Dular, Patrick ; Geuzaine, Christophe et al in Proceedings of the 14th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC2010) (2010, May) In this paper a hybrid approach for considering massive conducting regions in time-domain finite-element modeling is presented. Surface impedance boundary conditions, developed in the time domain as ... [more ▼] In this paper a hybrid approach for considering massive conducting regions in time-domain finite-element modeling is presented. Surface impedance boundary conditions, developed in the time domain as previously proposed by the authors, are adopted so as to allow for high-frequency flux components (in a certain frequency band) without the need for very fine discretisation of the conducting region near its surface. These surface conditions are combined with a coarse FE mesh inside the region for conveying slowly varying flux components. The correct impedance behaviour can thus be obtained in a wide frequency range, from DC flux on. The approach is briefly demonstrated by means of a simple 1D test case. [less ▲] Detailed reference viewed: 38 (5 ULg)A model reduction algorithm for solving multiple scattering problems using iterative methods Vion, Alexandre ; V Sabariego, Ruth ; Geuzaine, Christophe This paper presents a new method for solving scattering problems by multiple objects. A model reduction algorithm based on the Macro Basis Functions (MBFs) method is used to find an approximate solution ... [more ▼] This paper presents a new method for solving scattering problems by multiple objects. A model reduction algorithm based on the Macro Basis Functions (MBFs) method is used to find an approximate solution within a subspace of solutions, that are the solutions of several single scattering subproblems. Different iterative methods for the generation of the MBFs are compared. The whole process relies on a finite element approach and is applied to convex obstacles scattering. [less ▲] Detailed reference viewed: 47 (13 ULg) |
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