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See detailSubproblem Approach for Modeling Multiply Connected Thin Regions with an h-Conformal Magnetodynamic Finite Element Formulation
Dang, Quoc Vuong ULg; Dular, Patrick ULg; Vazquez Sabariego, Ruth ULg et al

in European Physical Journal : Applied physics (2013), in press

A subproblem h-conformal eddy current nite element method is proposed for correcting the inaccuracies inherent to thin shell models. Such models replace volume thin regions by surfaces but neglect border ... [more ▼]

A subproblem h-conformal eddy current nite element method is proposed for correcting the inaccuracies inherent to thin shell models. Such models replace volume thin regions by surfaces but neglect border e ects in the vicinity of their edges and corners. The developed surface-to-volume correction problem is de ned as a step of the multiple subproblems that can split a complete problem, consisting of inductors and magnetic or conducting regions, some of these being thin regions. The general case of multiply connected thin regions is considered [less ▲]

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See detailModeling of Electromagnetic Systems by Coupling of Subproblems – Application to Thin Shell Finite Element Magnetic Models
Dang, Quoc Vuong ULg

Doctoral thesis (2013)

The direct application of the finite element method to realistic electromagnetic problems is challenging, especially when modeling structures with thin conductive and/or magnetic parts. This work presents ... [more ▼]

The direct application of the finite element method to realistic electromagnetic problems is challenging, especially when modeling structures with thin conductive and/or magnetic parts. This work presents a subproblem method for correcting the inaccuracies inherent to classical thin shell models, and to efficiently handle geometrical and material variations in parametric studies. [less ▲]

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See detailSubproblem h-Conform Formulation for Accurate Thin Shell Models Between Conducting and Nonconducting Regions
Dang, Quoc Vuong ULg; Dular, Patrick ULg; Vazquez Sabariego, Ruth ULg et al

in Proceeding of the 9th International Symposium on Electric and Magnetic Fields, EMF 2013 (2013, April 23)

A subproblem method (SPM) with h-formulation is developed for correcting the inaccuracies near edges and corners that arise from using thin shell (TS) models to replace thin volume regions by surfaces ... [more ▼]

A subproblem method (SPM) with h-formulation is developed for correcting the inaccuracies near edges and corners that arise from using thin shell (TS) models to replace thin volume regions by surfaces. The developed surface-to-volume correction problem is defined as a step of multiple SPs, with inductors and magnetic or conducting regions, some of them being thin. The TS model assumes that the fields in the thin regions are approximated by a priori 1-D analytical distributions along the shell thickness (C. Geuzaine et al., “Dual formulations for the modeling of thin electromagnetic shells using edge elements,” IEEE Trans. Magn., vol. 36, no. 4, pp. 799–802, 2000). Their interior is not meshed and ratherextracted from the studied domain, which is reduced to a zero-thickness double layer with interface conditions (ICs) linked to 1-D analytical distributions that however neglect end and curvature effects. This leads to inaccuracies near edges and corners that increase with the thickness. To cope with these difficulties, the authors have recently proposed a SPM based on the h-formulation for a thin region located between non-conducting regions (Vuong Q. Dang et al., “Subproblem Approach for Thin Shell Dual Finite Element Formulations”, IEEE Trans. Magn., vol. 48, no. 2, pp. 407–410, 2012). The magnetic field h is herein defined in nonconducting regions by means of a magnetic scalar potential , i.e. h = -grad{\phi} , with discontinuities of through the TS. In this paper, the SPM is extended to account for thin regions located between conducting regions or between conducting and nonconducting regions, in the general case of multiply connected regions. In these regions, the potential is not defined anymore on both sides of the TS and the problem has to be expressed in terms of the discontinuities of h, possibly involving on one side only, to be strongly defined via an IC through the TS. In the proposed SP strategy, a reduced problem with only inductors is first solved on a simplified mesh without thin and volume regions. Its solution gives surface sources (SSs) as ICs for added TS regions, and volume sources (VSs) for possible added volume regions. The TS solution is further improved by a volume correction via SSs and VSs that overcome the TS assumptions, respectively suppressing the TS model and adding the volume model. Each SP has its own separate mesh, which increases the computational efficiency. Details on the proposed method will be given in the extended paper, with practical applications. [less ▲]

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See detailDual Formulations for Accurate Thin Shell Models in a Finite Element Subproblem Method
Dang, Quoc Vuong ULg; Dular, Patrick ULg; Vazquez Sabariego, Ruth ULg et al

in Proceeding of the 19th COMPUMAG Conference on the Computation of Electromagnetic Fields, 2013 (2013, April 01)

A subproblem finite with dual finite element magnetostatic and magnetodynamic formulations is developed for correcting the inaccuracies near edges and corners coming from thin shell models, that replace ... [more ▼]

A subproblem finite with dual finite element magnetostatic and magnetodynamic formulations is developed for correcting the inaccuracies near edges and corners coming from thin shell models, that replace thin volume regions by surfaces. The surface-to-volume correction problem is defined as one of the multiple subproblems applied to a complete problem, considering successive additions of inductors and magnetic or conducting regions, some of these being thin regions. Each SP requires a proper adapted mesh of its regions, which facilitates meshing and increases computational e ciency. [less ▲]

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See detailAccurate h-Conform Finite Element Model of Multiply Connected Thin Regions via a Subproblem Method
Dang, Quoc Vuong ULg; Dular, Patrick ULg; Vazquez Sabariego, Ruth ULg et al

in Proceedings of the 15th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC2012) (2012, November)

A subproblem method for solving eddy current finite element is developed to correct the inaccuracies near edges and corners arising from thin shell models. Such models replace thin volume regions by ... [more ▼]

A subproblem method for solving eddy current finite element is developed to correct the inaccuracies near edges and corners arising from thin shell models. Such models replace thin volume regions by surfaces but neglect border effects in the vicinity of their edges and corners. A thin shell solution, performed by a simplified mesh near the thin structures, serves as a source of a correction problem consisting of the actual volume thin regions alone and concentrating the meshing effort on the thin regions. The general case of multiply connected thin regions is considered. [less ▲]

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See detailSubproblem h-Conform Magnetodynamic Finite Element Formulation for Accurate Model of Multiply Connected Thin Regions
Dang, Quoc Vuong ULg; Dular, Patrick ULg; Vazquez Sabariego, Ruth ULg et al

in Proceedings of the 7th European Conference on Numerical Methods in Electromagnetism (NUMELEC 2012) (2012, July 03)

A subproblem $\vh$-conform eddy current finite element method is proposed for correcting the inaccuracies inherent to thin shell models. Such models replace volume thin regions by surfaces but neglect ... [more ▼]

A subproblem $\vh$-conform eddy current finite element method is proposed for correcting the inaccuracies inherent to thin shell models. Such models replace volume thin regions by surfaces but neglect border effects in the vicinity of their edges and corners. The developed surface-to-volume correction problem is defined as a step of the multiple subproblems applied to a complete problem, consisting of inductors and magnetic or conducting regions, some of these being thin regions. The general case of multiply connected thin regions is considered. [less ▲]

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See detailSubproblem Approach for Thin Shell Dual Finite Element Formulations
Dang, Quoc Vuong ULg; Dular, Patrick ULg; Vazquez Sabariego, Ruth ULg et al

in IEEE Transactions on Magnetics (2012), 48(2), 407-410

A subproblem technique is applied to dual thin shell finite element formulations. Both the magnetic vector potential and magnetic field formulations are considered. The subproblem approach developed ... [more ▼]

A subproblem technique is applied to dual thin shell finite element formulations. Both the magnetic vector potential and magnetic field formulations are considered. The subproblem approach developed herein couples three problems: a simplified model with only inductors, a thin region problem using approximate interface conditions and a correction problem to improve the accuracy of the thin shell approximation, in particular near their edges and corners. Each problem has its own geometry and is solved on its associated finite element mesh. [less ▲]

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See detailInfluence of contact resistance on shielding efficiency of shielding gutters for high-voltage cables
Koroglu, S.; Sergeant, P.; V Sabariego, Ruth ULg et al

in IET Electric Power Applications (2011), 5(9), 715-720

The shielding of buried three-phase high-voltage power lines can be done by placing them in conducting ferromagnetic U-shaped gutters covered with plates. In case of a perfect electrical contact between ... [more ▼]

The shielding of buried three-phase high-voltage power lines can be done by placing them in conducting ferromagnetic U-shaped gutters covered with plates. In case of a perfect electrical contact between adjacent gutters and between adjacent cover plates, induced currents in the shield efficiently reduce the magnetic field generated by the cables. As however a perfect contact cannot be guaranteed, in practice, it is useful to quantify the effect of a defective electrical contact on the field reduction. From two-dimensional/three-dimensional finite element computations and experiments, the influence of the contact resistance on the shielding efficiency is investigated, as a function of the ratio of axial length to height of the shield elements. Furthermore, the effect of other parameters on the shielding efficiency is studied: the ratio of axial length to height, a parasitic air gap between the gutter and the cover plate and the type of the shield material. It was found that a low contact resistance deteriorates much more the shielding in case of an aluminium shield than in case of a steel shield. As expected, the effect is larger for shield elements with relatively short axial length with regard to the other dimensions. Nevertheless, the effect remains quite significant for aluminium shields with practically convenient dimensions. [less ▲]

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See detailSubproblem method with dual finite element formulations for accurate thin shell models
Dang, Quoc Vuong ULg; Dular, Patrick ULg; V Sabariego, Ruth ULg et al

in Proceedings of the XV International Symposium on Electromagnetic Fields in Mechatronics, Electrical and Electronic Engineering (ISEF2011) (2011, September)

A subproblem method with dual finite element magnetostatic and magnetodynamic formulations is developed to correct the inaccuracies near edges and corners coming from thin shell models, that replace thin ... [more ▼]

A subproblem method with dual finite element magnetostatic and magnetodynamic formulations is developed to correct the inaccuracies near edges and corners coming from thin shell models, that replace thin volume regions by surfaces. The surface-to-volume correction problem is defined as one of the multiple subproblems applied to a complete problem, considering successive additions of inductors and magnetic or conducting regions, some of these being thin regions. Each subproblem is independently solved on its own domain and mesh, which facilitates meshing and solving while controlling the importance and usefulness of each correction. Parameterized analyses of thin regions are efficiently performed. [less ▲]

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See detailEvaluation of Eddy Losses Due to High Current Leads in Transformers Using a Subproblem Method
V.Ferreira da Luz, Mauricio; Dular, Patrick ULg; Dang, Quoc Vuong ULg et al

in ISEF 2011 - XV International Symposium on Electromagnetic Fields in Mechatronics, Electrical and Electronic Engineering (ISEF2011 ) (2011, September)

A subproblem finite element method is developed for evaluating the eddy losses due to high current leads in transformers. The structural component of the transformer is modeled with classical volumetric ... [more ▼]

A subproblem finite element method is developed for evaluating the eddy losses due to high current leads in transformers. The structural component of the transformer is modeled with classical volumetric elements or more efficiently with a thin shell model (surface impedance technique). Tools are then developed to correct the inaccuracies near edges and corners inherent to thin shell models for magnetodynamic problems. Improvements of local fields make possible accurate calculations of eddy losses and of temperature rise. [less ▲]

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See detailSubproblem Approach for Thin Shell Dual Finite Element Formulations
Dang, Quoc Vuong ULg; Dular, Patrick ULg; V Sabariego, Ruth ULg et al

in Proceedings of the 18th Conference on the Computation of Electromagnetic Fields (COMPUMAG2011) (2011, July)

A subproblem technique is applied on dual formu- lations to the solution of thin shell finite element models. Both the magnetic vector potential and magnetic field formulations are considered. The ... [more ▼]

A subproblem technique is applied on dual formu- lations to the solution of thin shell finite element models. Both the magnetic vector potential and magnetic field formulations are considered. The subproblem approach developed herein couples three problems: a simplified model with inductors alone, a thin region problem using approximate interface conditions, and a correction problem to improve the accuracy of the thin shell approximation, in particular near their edges and corners. Each problem is solved on its own independently defined geometry and finite element mesh. [less ▲]

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See detailCorrection of Thin Shell Finite Element Magnetic Models via a Subproblem Method
Dular, Patrick ULg; Dang, Quoc Vuong ULg; Vazquez Sabariego, Ruth ULg et al

in IEEE Transactions on Magnetics (2011), 47(5), 1158-1161

A subproblem 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 subproblem 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 ▲]

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See detailInfluence of contact resistance on shielding efficiency of shielding gutters for HV cables
Koruglu, Selim; Sergeant, Peter; V Sabariego, Ruth ULg et al

in Proceedings of the 14th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC2010) (2010, May)

Shielding of buried three phase high voltage cables can be done by placing the cables in conducting ferromagnetic U- shaped gutters covered by plates. In case of a perfect electrical contact between ... [more ▼]

Shielding of buried three phase high voltage cables can be done by placing the cables in conducting ferromagnetic U- shaped gutters covered by plates. In case of a perfect electrical contact between adjacent gutters and between adjacent cover plates, the induced currents in the shield efficiently reduce the field generated in the vicinity of the cables. However, as a perfect contact cannot be guaranteed, it is useful to quantify the effect of a bad electrical contact on the shielding performance. From 2D FEM, 3D FEM and experiments, it is observed that a bad contact does not influence significantly the shielding if the axial length of the plates is relatively long compared to their other dimensions. [less ▲]

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See detailCorrection of Thin Shell Finite Element Magnetic Models via a Subproblem Method
Dular, Patrick ULg; Dang, Quoc Vuong ULg; V Sabariego, Ruth ULg 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: 58 (31 ULg)
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See detailInfluence of contact resistance on shielding efficiency of shielding gutters for HV cables
Koroglu, Selim; Sergeant, Peter; V Sabariego, Ruth ULg et al

in Proceedings of the 14th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC2010) (2010)

Shielding of buried three phase high voltage cables can be done by placing the cables in conducting ferromagnetic U-shaped gutters covered by plates. In case of a perfect electrical contact between ... [more ▼]

Shielding of buried three phase high voltage cables can be done by placing the cables in conducting ferromagnetic U-shaped gutters covered by plates. In case of a perfect electrical contact between adjacent gutters and between adjacent cover plates, the induced currents in the shield efficiently reduce the field generated in the vicinity of the cables. However, as a perfect contact cannot be guaranteed, it is useful to quantify the effect of a bad electrical contact on the shielding performance. From 2D FEM, 3D FEM and experiments, it is observed that a bad contact does not influence significantly the shielding if the axial length of the plates is relatively long compared to their other dimensions. [less ▲]

Detailed reference viewed: 31 (7 ULg)