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: 64 (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: 91 (14 ULg)Toward Convergent Methods for High-Frequency Wave Problems Geuzaine, Christophe Scientific conference (2010, July 15) Detailed reference viewed: 13 (7 ULg)High-quality remeshing using harmonic maps Geuzaine, Christophe ; ; in Proceedings of the 5th Advanced Computational Electromagnetics workshop (2010, July) Detailed reference viewed: 8 (1 ULg)GetDP et Gmsh Geuzaine, Christophe Scientific conference (2010, June 16) Detailed reference viewed: 62 (6 ULg)High Quality Surface Meshing using Harmonic Maps Geuzaine, Christophe Scientific conference (2010, June 09) Detailed reference viewed: 8 (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: 15 (1 ULg)Passive ACS of Delphi-C3 nanosatellite ; ; Geuzaine, Christophe in Proceedings of the URSI Forum 2010 (2010, May) Detailed reference viewed: 18 (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: 24 (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: 60 (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: 32 (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: 41 (13 ULg)High Performance Algorithms for High-Order High-Frequency Electromagnetic Scattering Geuzaine, Christophe Scientific conference (2010, April 28) Detailed reference viewed: 18 (2 ULg)Numerical methods for Electromagnetic Field Modeling, from quasistatic to high-frequency problems Geuzaine, Christophe Scientific conference (2010, March 31) Detailed reference viewed: 33 (4 ULg)High-Quality Remeshing using Harmonic Maps Geuzaine, Christophe Scientific conference (2010, March 30) Detailed reference viewed: 7 (0 ULg)Refinement of Inductor Models via a Subproblem Finite Element Method Dular, Patrick ; ; et al in Proceedings of the 14th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC2010) (2010) A sub-problem finite element method is developed for refining the inductor models in magnetic circuits. It applies electrokinetic, magnetostatic and magnetodynamic models on progressively more complicated ... [more ▼] A sub-problem finite element method is developed for refining the inductor models in magnetic circuits. It applies electrokinetic, magnetostatic and magnetodynamic models on progressively more complicated geometries and different components of the solution, supported by different meshes. It allows an efficient and robust analyze of magnetic circuits in any frequency range, with an accurate calculation of Joule losses and forces in inductors. [less ▲] Detailed reference viewed: 25 (1 ULg)Finite-Element Analysis of a Shielded Pulsed-Current Induction Heater -- Experimental Validation of a Time-Domain Thin-Shell Approach V Sabariego, Ruth ; ; et al in COMPEL (2010), 29(6), 1585-1595 Purpose – The aim of this paper is the experimental validation of an original time-domain thin-shell formulation. The numerical results of a three-dimensional thin-shell model are compared with the ... [more ▼] Purpose – The aim of this paper is the experimental validation of an original time-domain thin-shell formulation. The numerical results of a three-dimensional thin-shell model are compared with the measurements performed on a heating device at different working frequencies. Design/methodology/approach – A time-domain extension of the classical frequency-domain thin-shell approach is used for the finite-element analysis of a shielded pulse-current induction heater. The time-domain interface conditions at the shell surface are expressed in terms of the average flux density vector in the shell, as well as in terms of a limited number of higher-order components. Findings – A very good agreement between measurements and simulations is observed. A clear advantage of the proposed thin-shell approach is that the mesh of the computation domain does not depend on the working frequency anymore. It provides a good compromise between computational cost and accuracy. Indeed, adding a sufficient number of induction components, a very high accuracy can be achieved. Originality/value – The method is based on the coupling of a time-domain 1D thin-shell model with a magnetic vector potential formulation via the surface integral term. A limited number of additional unknowns for the magnetic flux density are incorporated on the shell boundary. [less ▲] Detailed reference viewed: 38 (2 ULg)Magnetic model refinement via a coupling of finite element subproblems Dular, Patrick ; V Sabariego, Ruth ; et al in Proceedings of Scientific Computing in Electrical Engineering (SCEE 2010) (2010) Model refinements of magnetic circuits are performed via a subdomain finite element method. A complete problem is split into subproblems with overlap- ping meshes, to allow a progression from source to ... [more ▼] Model refinements of magnetic circuits are performed via a subdomain finite element method. A complete problem is split into subproblems with overlap- ping meshes, to allow a progression from source to reaction fields, ideal to real flux tubes, 1-D to 3-D models, perfect to real materials, statics to dynamics, with any coupling of these changes. Its solution is then the sum of the subproblem solutions. The procedure simplifies both meshing and solving processes, and quantifies the gain given by each refinement on both local fields and global quantities. [less ▲] Detailed reference viewed: 14 (1 ULg)Iterative solution of high-frequency multiple-scattering problems using finite elements Geuzaine, Christophe ; Vion, Alexandre ; V Sabariego, Ruth in Proceedings of the IVth European Conference on Computational Mechanics (ECCM 2010) (2010) Detailed reference viewed: 39 (17 ULg)Dual approach for an accurate estimation of pull-in voltage Rochus, Véronique ; Lemaire, Etienne ; Geuzaine, Christophe in Proceedings of the IVth European Conference on Computational Mechanics (ECCM 2010) (2010) Detailed reference viewed: 28 (21 ULg) |
||