References of "Geuzaine, Christophe"
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See detailExperimental Correction of Radiation Patterns Between Electromagnetic Environments
Spirlet, Maxime ULg; Geuzaine, Christophe ULg; Beauvois, Véronique ULg

in IEEE Transactions on Antennas & Propagation (2017), 65(03),

This manuscript presents an experimental method to estimate a radiation pattern obtained in a particular echoic environment (for example from in-situ measurements) as if measurements were performed in a ... [more ▼]

This manuscript presents an experimental method to estimate a radiation pattern obtained in a particular echoic environment (for example from in-situ measurements) as if measurements were performed in a given anechoic chamber. The correction is achieved using some reference measurements collected both in echoic and anechoic environments. An angular transfer function is estimated from these two sets of measurements and deconvolved from the measured radiation pattern to be corrected. [less ▲]

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See detailPerfectly matched layers for convex truncated domains with discontinuous Galerkin time domain simulations
Modave, Axel; Lambrechts, Jonathan; Geuzaine, Christophe ULg

in Computers & Mathematics with Applications (2017), 73(4), 684-700

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See detailOptimized Schwarz Domain Decomposition Methods for Scalar and Vector Helmholtz Equations
Antoine, Xavier; Geuzaine, Christophe ULg

in Lahaye, Domenico; Tang, Jok; Vuik, Kees (Eds.) Modern Solvers for Helmholtz Problems (2017)

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See detailDesign sensitivity analysis for shape optimization based on the Lie derivative
Kuci, Erin ULg; Henrotte, François ULg; Duysinx, Pierre ULg et al

in Computer Methods in Applied Mechanics & Engineering (2017)

Abstract The paper presents a theoretical framework for the shape sensitivity analysis of systems governed by partial differential equations. The proposed approach, based on geometrical concepts borrowed ... [more ▼]

Abstract The paper presents a theoretical framework for the shape sensitivity analysis of systems governed by partial differential equations. The proposed approach, based on geometrical concepts borrowed from differential geometry, shows that sensitivity of a performance function (i.e. any function of the solution of the problem) with respect to a given design variable can be represented mathematically as a Lie derivative, i.e. the derivative of that performance function along a flow representing the continuous shape modification of the geometrical model induced by the variation of the considered design variable. Theoretical formulae to express sensitivity analytically are demonstrated in detail in the paper, and applied to a nonlinear magnetostatic and a linear elastic problem, following both the direct and the adjoint approaches. Following the analytical approach, one linear system of which only the right-hand side needs be evaluated (the system matrix being known already) has to be solved for each of the design variables in the direct approach, or for each performance functions in the adjoint approach. A substantial gain in computation time is obtained this way compared to a finite difference evaluation of sensitivity, which requires solving a second nonlinear system for each design variable. This is the main motivation of the analytical approach. There is some freedom in the definition of the auxiliary flow that represents the shape modification. We present a method that makes benefit of this freedom to express sensitivity locally as a volume integral over a single layer of finite elements connected to both sides of the surfaces undergoing shape modification. All sensitivity calculations are checked with a finite difference in order to validate the analytic approach. Convergence is analyzed in 2D and 3D, with first and second order finite elements. [less ▲]

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See detailWaveform relaxation for the computational homogenization of multiscale magnetoquasistatic problems
Niyonzima, Innocent; Geuzaine, Christophe ULg; Schöps, Sebastian

in Journal of Computational Physics (2016), 327

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See detailShape and Topology Optimization of Electrical Machines using Lie Derivative-Based Analytical Sensitivity Analysis
Kuci, Erin ULg; Henrotte, François ULg; Duysinx, Pierre ULg et al

Scientific conference (2016, November 13)

The paper addresses the optimal design of electric machines, through the general setting of both shape and topology optimization. The optimization problems are efficiently solved with a classical gradient ... [more ▼]

The paper addresses the optimal design of electric machines, through the general setting of both shape and topology optimization. The optimization problems are efficiently solved with a classical gradient-based mathematical programming algorithm. An analytical sensitivity analysis for the nonlinear magnetostatic problem that can handle both shape and topology design variables, based on the Lie derivative is derived and applied to the optimal design of an interior permanent magnet (IPM) machine. [less ▲]

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See detailEfficient Computation of the Minimum of Shape Quality Measures on Curvilinear Finite Elements
Johnen, Amaury ULg; Geuzaine, Christophe ULg; Toulorge, Thomas et al

in Procedia Engineering (2016, November), 163

We present a method for computing robust shape quality measures defined for any order of finite elements. All type of elements are considered, including pyramids. The measures are defined as the minimum ... [more ▼]

We present a method for computing robust shape quality measures defined for any order of finite elements. All type of elements are considered, including pyramids. The measures are defined as the minimum of the pointwise quality of curved elements. The computation of the minimum, based on previous work presented by Johnen et al. (2013) [1] and [2], is very efficient. The key feature is to expand polynomial quantities into Bézier bases which allows to compute sharp bounds on the minimum of the pointwise quality measures. [less ▲]

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See detailUsing a Jiles‐Atherton vector hysteresis model for isotropic magnetic materials with the finite element method, Newton‐Raphson method, and relaxation procedure
Guérin, Christophe; Jacques, Kevin ULg; Vazquez Sabariego, Ruth et al

in International Journal of Numerical Modelling: Electronic Networks, Devices and Fields (2016)

This paper deals with the use of a Jiles‐Ather ton vector hysteresis model included in 2D finite element modeling. The hysteresis model is only valid for isotropic materials. It is implemented with the ... [more ▼]

This paper deals with the use of a Jiles‐Ather ton vector hysteresis model included in 2D finite element modeling. The hysteresis model is only valid for isotropic materials. It is implemented with the vector potential formulation in 2D along with electric circuit equations to account for a possible external circuit. The Newton‐Raphson algorithm is used with a relaxation procedure, whereby at each iteration, th e relaxation coefficient is sought so as to minimize the Euclidean norm of the residual of the finite element nonlinear system of equations. We have simulated several numerical examples with the proposed approach. First, simulation s on a square domain were conducted so as to validate the model. We have further simulated a T‐shaped magnetic circuit (exhibiting rotating flux) and a 3‐phase 3‐limb transformer model. For these 2 cases, the eddy current losses in the laminations are taken into account by a low‐frequency model. We have finally performed simulations on the TEAM workshop problem 32, which consists of a 3‐limb transformer with 2 windings, for which current and local magnetic flux density measurements are available. We obtained a good agreement between computed and measured results. [less ▲]

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See detailCo-simulation of Electromagnetic Transients and Phasor Models: a Relaxation Approach
Plumier, Frédéric ULg; Aristidou, Petros; Geuzaine, Christophe ULg et al

in IEEE Transactions on Power Delivery (2016), 31(5),

Co-simulation opens new opportunities to combine mature ElectroMagnetic Transients (EMT) and Phasor-Mode (PM) solvers, and take advantage of their respective high accuracy and execution speed. In this ... [more ▼]

Co-simulation opens new opportunities to combine mature ElectroMagnetic Transients (EMT) and Phasor-Mode (PM) solvers, and take advantage of their respective high accuracy and execution speed. In this paper, a relaxation approach is presented, iterating between an EMT and a PM solver. This entails interpolating over time the phasors of the PM simulation, extracting phasors from the time evolutions of the EMT simulation, and representing each sub-system by a proper multiport equivalent when simulating the other sub-system. Various equivalents are reviewed and compared in terms of convergence of the PM-EMT iterations. The paper also considers the update with frequency of the Thévenin impedances involved in the EMT simulation, the possibility to compute the EMT solution only once per time step, and the acceleration of convergence through a prediction over time of the boundary variables. Results are presented on a 74-bus, 23-machine test system, split into one EMT and one PM sub-system with several interface buses. [less ▲]

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See detailEstimation of semi-anechoic chamber radiation patterns from in-situ measurements using the angular responses of the environment
Spirlet, Maxime ULg; Geuzaine, Christophe ULg; Beauvois, Véronique ULg

Conference (2016, July 11)

This paper presents an experimental method to estimate a radiation pattern obtained in a particular echoic environment (for example from in-situ measurements) as if measurements were performed in a given ... [more ▼]

This paper presents an experimental method to estimate a radiation pattern obtained in a particular echoic environment (for example from in-situ measurements) as if measurements were performed in a given (semi or full) anechoic chamber. To achieve the correction of the radiation pattern, some reference measurements have to be collected in the echoic and anechoic environments. Using these two sets of measurements, an angular transfer function is built and deconvolved from the measured radiation pattern to be corrected. [less ▲]

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See detailNumerical Properties of a Discontinuous Galerkin formulation for electro-thermal coupled problems
Homsi, Lina; Geuzaine, Christophe ULg; Noels, Ludovic ULg

in Papadrakakis, M.; Papadopoulos, V.; Stefanou, G. (Eds.) et al Proceedings of the VII European Congress on Computational Methods in Applied Sciences and Engineering, Crete Island, Greece, 5–10 June 2016 (2016, June 05)

Discontinuous Galerkin (DG) methods are attractive tools to integrate several PDEs in engineering sciences, due to their high order accuracy and their high scalability in parallel simulations. The main ... [more ▼]

Discontinuous Galerkin (DG) methods are attractive tools to integrate several PDEs in engineering sciences, due to their high order accuracy and their high scalability in parallel simulations. The main interest of this work is to derive a constant and stable Discontinuous Galerkin method for two-way electro-thermal coupling analyses. A fully coupled nonlinear weak formulation for electro-thermal problems is developed based on continuum mechanics equations which are discretized using the Discontinuous Galerkin method. Toward this end, the weak form is written in terms of energetically conjugated fields gradients and fluxes. In order to validate the effectiveness of the formulation and illustrate the algorithmic properties, a numerical test for composite materials is performed. [less ▲]

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See detailEfficient Computation of the Extrema of Algebraic Quality Measures for Curvilinear Finite Elements
Johnen, Amaury ULg; Geuzaine, Christophe ULg; remacle, Jean-François

Conference (2016, June)

The development of high-order computational methods for solving partial differential equations on unstructured grids has been underway for many years. Such methods critically depend on the availability of ... [more ▼]

The development of high-order computational methods for solving partial differential equations on unstructured grids has been underway for many years. Such methods critically depend on the availability of high-quality curvilinear meshes, as one bad element can degrade the solution in the whole domain. The usual way of generating curved meshes is to first generate a (high-quality) straight-sided mesh. Then, mesh entities that are classified on the boundaries of the domain are curved. This operation introduces a "shape-distortion" that should be controlled. Quality measures allow to quantify to which point an element is well-shaped. They also provide tools to improve the quality of meshes through optimization. In this work we propose an efficient method to compute several quality measures for curved elements, based on the Jacobian of the mapping between the straight-sided elements and the curved ones. Contrary to the approach presented in "A. Gargallo-Peiró, X. Roca, J. Peraire, and J. Sarrate. Distortion and quality measures for validating and generating high-order tetrahedral meshes. Engineering with Computers, pages 1–15, 2014.", which relies on an L2-norm over the elements, we compute the actual minimum and maximum of the local quality measure for each element. The method is an extension of previous works on the validity of those elements (A. Johnen et al., 2013). The key feature is that we can adaptively expand functions based on the Jacobian matrix and its determinant in terms of Bézier functions. Bézier functions have both properties of boundedness and positivity, which allow sharp computation of minimum or maximum of the interpolated functions. [less ▲]

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See detailAutomatic derivation of multiharmonic formulations for nonlinear electromechanical problems with time dependent mesh deformation
Halbach, Alexandre ULg; Geuzaine, Christophe ULg

in 17th International Conference on Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems (EuroSimE) (2016, May 05)

This paper describes a method to automatically derive multiharmonic finite element formulations for coupled, nonlinear electromechanical problems. It focuses on models of electrically actuated ... [more ▼]

This paper describes a method to automatically derive multiharmonic finite element formulations for coupled, nonlinear electromechanical problems. It focuses on models of electrically actuated micromembranes using both a staggered and a monolithic Newton iteration scheme. Two- and three-dimensional examples highlight the main properties of the proposed method. [less ▲]

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See detailProper orthogonal decomposition versus Krylov subspace methods in reduced-order energy-converter models
Hasan M.D., Rokibul; V. Sabariego, Ruth; Geuzaine, Christophe ULg et al

Conference (2016, April)

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See detailFrame field smoothness-based approach for hex-dominant meshing
Bernard, Paul-Emile; Remacle, Jean-François; Kowalski, Nicolas et al

in Computer-Aided Design (2016), 72

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See detailNonlinear Interpolation on Manifold of Reduced Order Models in Magnetodynamic Problems
Paquay, Yannick ULg; Bruls, Olivier ULg; Geuzaine, Christophe ULg

in IEEE Transactions on Magnetics (2016), 52(3), 1-4

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See detailReduced Order Model for Accounting for High Frequency Effects in Power Electronic Components
Paquay, Yannick ULg; Geuzaine, Christophe ULg; Hasan, Md. Rokibul et al

in IEEE Transactions on Magnetics (2016)

Detailed reference viewed: 86 (20 ULg)