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A finite-element solution for EEG forward modeling with realistic individual head models ; Geuzaine, Christophe ; Phillips, Christophe Poster (2015, June) Detailed reference viewed: 31 (6 ULg)Progressive inductor modeling via a finite element subproblem method Dular, Patrick ; ; et al in COMPEL (2015), 34(3), 851-863 Purpose – The purpose of this paper is to develop a subproblem method (SPM) for progressive modeling of inductors, with model refinements of both source conductors and magnetic cores. Design/methodology ... [more ▼] Purpose – The purpose of this paper is to develop a subproblem method (SPM) for progressive modeling of inductors, with model refinements of both source conductors and magnetic cores. Design/methodology/approach – The modeling of inductors is split into a sequence of progressive finite element (FE) SPs. The source fields (SFs) generated by the source conductors alone are calculated at first via either the Biot-Savart (BS) law or FEs. With a novel general way to define the SFs via interface conditions (ICs), to lighten their evaluation process, the associated reaction fields for each added or modified region, mainly the magnetic cores, and in return for the source conductor regions themselves when massive, are then calculated with FE models. Changes of magnetic regions go from perfect magnetic properties up to volume linear and nonlinear properties, and from statics to dynamics. Findings – For any added or modified region, the novel proposed ICs to define the SFs appear of general usefulness, which opens the method to a wide range of model improvements. Originality/value – The resulting SPM allows efficient solving of parameterized analyses thanks to a proper mesh for each SP and the reuse of previous solutions to be locally corrected, in association with novel SF ICs that strongly lighten the quantity of BS evaluations. Significant corrections are progressively obtained for the fields, up to nonlinear magnetic core properties and skin and proximity effects in conductors, and for the related inductances and resistances. [less ▲] Detailed reference viewed: 21 (2 ULg)Subproblem Finite-Element Refinement of Homogenized Dielectric Layers in Wound Inductors for Accurate Local Stresses Computation ; Dular, Patrick ; et al in IEEE Transactions on Magnetics (2015), 51(3), Recently, a homogenized model in 2-D electrostatics has been proposed in order to avoid the meshing of the thin dielectric layers surrounding the conductors of transformers. The model performs a smoothing ... [more ▼] Recently, a homogenized model in 2-D electrostatics has been proposed in order to avoid the meshing of the thin dielectric layers surrounding the conductors of transformers. The model performs a smoothing of the physical fields, which leads to an incorrect estimation of the peak values of the electric field between the conductors. This issue is critical for a correct design of the transformer insulation. Therefore, in this paper, the subproblem finite-element method is employed, so as to refine the homogenized model on selected areas, and recover the small scale variations of the fields. [less ▲] Detailed reference viewed: 10 (0 ULg)Refinement of Homogenized Magnetodynamic Models of Wound Inductors Using Finite-Element Subproblems ; Dular, Patrick ; Gyselinck, Johan et al in IEEE Transactions on Magnetics (2015), 51(3), In this paper, a methodology for refining the large-scale solutions obtained by 2-D magnetodynamic homogenized models of high-frequency inductor windings is proposed, based on the subproblem finite ... [more ▼] In this paper, a methodology for refining the large-scale solutions obtained by 2-D magnetodynamic homogenized models of high-frequency inductor windings is proposed, based on the subproblem finite-element method. Two approaches are developed, depending on the type of source terms, which are employed to compute the corrections (namely, volumic or surfacic). An analysis of the error committed by the homogenized model, on the local (current densities in the conductors) as well as the global (resistance of the winding) level, is conducted, and appropriate correction strategies are proposed. For instance, it is shown that correcting some conductors in the vicinity of the air gap of an inductor is sufficient to get an acceptable value for the resistance. [less ▲] Detailed reference viewed: 8 (0 ULg)Subproblem Finite-Element Refinement of Inductors From Wire to Static and Dynamic Volume Models Dular, Patrick ; ; et al in IEEE Transactions on Magnetics (2015), 51(3), Progressive refinements of inductors are done with a subproblem method, from their wire or filament representations with Biot–Savart models up to their volume finite-element models, from statics to ... [more ▼] Progressive refinements of inductors are done with a subproblem method, from their wire or filament representations with Biot–Savart models up to their volume finite-element models, from statics to dynamics. The reaction fields of additional magnetic and/or conducting regions are also considered. Accuracy improvements are efficiently obtained for local fields and global quantities, i.e., inductances, resistances, Joule losses, and forces. [less ▲] Detailed reference viewed: 20 (0 ULg)Efficient finite element assembly of high order Whitney forms Marsic, Nicolas ; Geuzaine, Christophe in IET Science, Measurement & Technology (2015), 9(2), 204-210 This study presents an efficient method for the finite element assembly of high order Whitney elements. The authors start by reviewing the classical assembly technique and by highlighting the most time ... [more ▼] This study presents an efficient method for the finite element assembly of high order Whitney elements. The authors start by reviewing the classical assembly technique and by highlighting the most time consuming part. Then, they show how this classical approach can be reformulated into a computationally efficient matrix-matrix product. They also address the global orientation problem of the vector valued basis functions. They conclude by presenting numerical results for a three-dimensional wave propagation problem. [less ▲] Detailed reference viewed: 74 (28 ULg)The generation of valid curvilinear meshes Geuzaine, Christophe ; Johnen, Amaury ; et al in IDIHOM: Industrialization of High-Order Methods - A Top-Down Approach (2015) Detailed reference viewed: 25 (3 ULg)Computational advances in quasi-optimal domain decomposition methods for time-harmonic electromagnetic wave problems Marsic, Nicolas ; Vion, Alexandre ; Geuzaine, Christophe Conference (2015) In this talk we will present recent advances in the construction of quasi-optimal domain decomposition methods for time-harmonic electromagnetic wave problems. In particular, we will discuss the parallel ... [more ▼] In this talk we will present recent advances in the construction of quasi-optimal domain decomposition methods for time-harmonic electromagnetic wave problems. In particular, we will discuss the parallel implementation and computational efficiency of sweeping-type preconditioners, as well as the use of high order finite element discretizations, potentially mixing orders for the volume and interface formulations. Results on several large scale test cases will be analysed. [less ▲] Detailed reference viewed: 32 (2 ULg)Anisotropic and feature sensitive triangular remeshing using normal lifting ; ; Geuzaine, Christophe in Journal of Computational and Applied Mathematics (2015), 289 Detailed reference viewed: 11 (1 ULg)Pragmatic two-step homogenisation technique for ferromagnetic laminated cores ; ; et al in IET Science, Measurement Technology (2015), 9(2), 152-159 Detailed reference viewed: 21 (2 ULg)A quasi-optimal domain decomposition algorithm for the time-harmonic Maxwell's equations ; ; et al in Journal of Computational Physics (2015), 294 Detailed reference viewed: 32 (4 ULg)A finite-element reciprocity solution for EEG forward modeling with realistic individual head models Ziegler, Erik ; Chellappa, Sarah Laxhmi ; Gaggioni, Giulia et al in NeuroImage (2014), 103 Highlights • Creates EEG forward models suitable for high-resolution source localization. • Automatic T1-based whole-head finite element meshing and leadfield computation. • Pipelines can incorporate ... [more ▼] Highlights • Creates EEG forward models suitable for high-resolution source localization. • Automatic T1-based whole-head finite element meshing and leadfield computation. • Pipelines can incorporate conductivity tensors from diffusion-weighted images. • Open-source toolbox shared under a permissive software license. • Accuracy comparable to SimBio FEM and superior to OpenMEEG BEM solutions. [less ▲] Detailed reference viewed: 101 (23 ULg)Optimizing Perfectly Matched Layers in Discrete Contexts Modave, Axel ; Delhez, Eric ; Geuzaine, Christophe in International Journal for Numerical Methods in Engineering (2014), 99(6), 410437 Perfectly Matched Layers (PMLs) are widely used for the numerical simulation of wave-like problems defined on large or infinite spatial domains. However, for both the time-dependent and the time-harmonic ... [more ▼] Perfectly Matched Layers (PMLs) are widely used for the numerical simulation of wave-like problems defined on large or infinite spatial domains. However, for both the time-dependent and the time-harmonic cases, their performance critically depends on the so-called absorption function. This paper deals with the choice of this function when classical numerical methods are used (based on finite differences, finite volumes, continuous finite elements and discontinuous finite elements). After reviewing the properties of the PMLs at the continuous level, we analyse how they are altered by the different spatial discretizations. In the light of these results, different shapes of absorption function are optimized and compared by means of both one- and two-dimensional representative time-dependent cases. This study highlights the advantages of the so-called shifted hyperbolic function, which is efficient in all cases and does not require the tuning of a free parameter, by contrast with the widely used polynomial functions. [less ▲] Detailed reference viewed: 106 (23 ULg)A relaxation scheme to combine Phasor-Mode and Electromagnetic Transients Simulations Plumier, Frédéric ; Aristidou, Petros ; Geuzaine, Christophe et al in Proceedings of the 18th Power System Computation Conference (2014, August) This paper deals with a new scheme for coupling phasor-mode and electromagnetic transients simulations. In each simulation, an iteratively updated linear equivalent is used to represent the effect of the ... [more ▼] This paper deals with a new scheme for coupling phasor-mode and electromagnetic transients simulations. In each simulation, an iteratively updated linear equivalent is used to represent the effect of the subsystem treated by the other simulation. Time interpolation and phasor extraction methods adapted to this scheme are presented and compared to existing methods. Finally, simulation results obtained with a 74-bus test system are reported. [less ▲] Detailed reference viewed: 173 (32 ULg)Geometrical validity of high-order pyramidal finite elements Johnen, Amaury ; Geuzaine, Christophe Conference (2014, July 24) Detailed reference viewed: 38 (15 ULg)Progressive inductor modeling via a finite element subproblem method Dular, Patrick ; ; Geuzaine, Christophe in Proceedings of EPNC 2014 - Electromagnetic phenomena in nonlinear circuits (2014, July) The modeling of inductors is split into a sequence of progressive finite element subproblems. The source fields generated by the coil conductors alone, with a wire representation, are calculated at first ... [more ▼] The modeling of inductors is split into a sequence of progressive finite element subproblems. The source fields generated by the coil conductors alone, with a wire representation, are calculated at first via either the Biot-Savart law or finite elements. The associated reaction fields for each added or modified region, mainly the magnetic cores, and in return for the source conductor regions themselves when massive, are then calculated with finite element models. Changes of magnetic regions go from perfect magnetic properties up to volume linear and nonlinear properties. 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 ▲] Detailed reference viewed: 15 (0 ULg)Progressive inductor modeling via a finite element subproblem method Dular, Patrick ; ; Geuzaine, Christophe in Proceedings of EPNC 2014 - Electromagnetic phenomena in nonlinear circuits (2014, July) The modeling of inductors is split into a sequence of progressive finite element subproblems. The source fields generated by the coil conductors alone, with a wire representation, are calculated at first ... [more ▼] The modeling of inductors is split into a sequence of progressive finite element subproblems. The source fields generated by the coil conductors alone, with a wire representation, are calculated at first via either the Biot-Savart law or finite elements. The associated reaction fields for each added or modified region, mainly the magnetic cores, and in return for the source conductor regions themselves when massive, are then calculated with finite element models. Changes of magnetic regions go from perfect magnetic properties up to volume linear and nonlinear properties. 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 ▲] Detailed reference viewed: 14 (0 ULg)On the convergence of relaxation schemes to couple phasor-mode and electromagnetic transients simulations Plumier, Frédéric ; Geuzaine, Christophe ; Van Cutsem, Thierry in Proceedings of the IEEE PES General Meeting (2014, July) Hybrid simulations combining phasor-mode and electromagnetic transients models aim at taking advantage of computational speed of the former and accuracy of the latter. For simulation accuracy, a ... [more ▼] Hybrid simulations combining phasor-mode and electromagnetic transients models aim at taking advantage of computational speed of the former and accuracy of the latter. For simulation accuracy, a relaxation process is used, which consists of iterating between both models. The convergence properties of this relaxation process are investigated. The speed of convergence is assessed when the variables exchanged at the interface between both models are respectively pure voltage/current sources, Norton/Thévenin equivalents, or a combination of them. Iteratively updated Norton/Thévenin equivalents are shown to drastically reduce the number of relaxation iterations. [less ▲] Detailed reference viewed: 122 (32 ULg)Optimizing the geometrical accuracy of 2D curvilinear finite element meshes ; ; et al Conference (2014, June 27) Detailed reference viewed: 27 (6 ULg)Double Sweep Preconditioners for propagation problems solved by Optimized Schwarz Methods Vion, Alexandre ; Geuzaine, Christophe in Proceedings of the 6th International Conference on Advanced COmputational Methods in ENgineering, ACOMEN 2014 (2014, June) Detailed reference viewed: 25 (7 ULg) |
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