Perturbation Finite Element Method for Magnetic Model Refinement of Air Gaps and Leakage Fluxes

in IEEE Transactions on Magnetics (2009), 45(3), 1400-1403

Model refinements of magnetic circuits are performed via a subproblem finite element method based on a perturbation technique. An approximate problem considering ideal flux tubes and simplified air-gap ... [more ▼]

Model refinements of magnetic circuits are performed via a subproblem finite element method based on a perturbation technique. An approximate problem considering ideal flux tubes and simplified air-gap models is first solved. It gives the sources for a finite element perturbation problem considering the actual air gaps and flux tubes geometries with the exterior regions. The procedure simplifies both meshing and solving processes, and allows to quantify the gain given by each model refinement. [less ▲]

Perturbation Finite Element Method for Magnetostatic and Magnetodynamic Problems

in Proceedings of MOMAG2008 (2008, September)

Magnetic flux distributions are calculated in magnetostatic and magnetodynamic problems via a subproblem finite element method based on a perturbation technique. An approximate finite element problem ... [more ▼]

Magnetic flux distributions are calculated in magnetostatic and magnetodynamic problems via a subproblem finite element method based on a perturbation technique. An approximate finite element problem considering ideal flux tubes or ideal materials is first solved. It gives the source for finite element perturbation problems considering the flux tubes with their exterior regions, accounting thus for leakage fluxes, as well as for changes of material properties and shapes. The proposed technique aims to accurately quantify the gain given by each model refinement on both local fields and global quantities and to justify the usefulness of this refinement. It is also well adapted to parameterized analyses on geometrical and material data. [less ▲]

A perturbation finite element method for modeling moving conductive and magnetic regions without remeshing

in COMPEL (2007), 26(3), 700-711

Purpose - To develop a sub-domain perturbation technique for efficiently modeling moving systems in magnetodynamics with a magnetic field h-conform finite element (FE) formulation. Design/methodology ... [more ▼]

Purpose - To develop a sub-domain perturbation technique for efficiently modeling moving systems in magnetodynamics with a magnetic field h-conform finite element (FE) formulation. Design/methodology/approach - A reference problem is first solved in a global mesh excluding some moving regions and thus avoiding the inclusion of their meshes. Its solution gives the sources for a sequence of perturbation problems with the supplementary moving magnetic and conductive regions. Each of these sub-problems requires an appropriate proper volume mesh of the associated moving region and its surrounding region, with no need of interconnection. The solutions are transferred from one problem to the other through projections of source fields between meshes. Findings - The consideration of sub-problems and associated sources, in a sequence of perturbation problems, leads to a significant speed-up of the repetitive solutions in analyses of moving systems. A free movement in any direction can be considered with no need of remeshing. Originality/value - When working with the perturbation fields, the volume sources can be limited to the moving regions, what allows for homogeneous perturbation boundary conditions and reduces the computational efforts for projecting and evaluating the sources. The curl-conformity of the unknown magnetic field is preserved during the whole process thanks to the use of edge FEs for both the magnetic field and the intermediate source quantities. The sub-problem approach also gives an easy way to directly express the time derivatives in moving frames. [less ▲]

Perturbation finite element method for the analysis of earthing systems with vertical and horizontal rods

in Proceedings of the 6ème Conférence Européenne sur les Méthodes Numériques en Electromagnétisme (NUMELEC2008) (2008, December)

This paper deals with the electrokinetic modeling of earthing systems by means of a sub-domain perturbation finite element technique. An axisymmetric problem is solved for each single grounding rod or ... [more ▼]

This paper deals with the electrokinetic modeling of earthing systems by means of a sub-domain perturbation finite element technique. An axisymmetric problem is solved for each single grounding rod or cable. Its solution must then be corrected by taking into account the influence of the other rods and cables. The electric scalar potential is transferred from one problem to the other through projections between meshes. An inherently 3D problem can thus be solved as a succession of 2D sub-problems, which significantly speeds up the solution and enables to tackle complicated grounding systems. [less ▲]

A Perturbation Finite Element Technique for Modeling Electrostatic MEMS

Poster (2008, March 18)

Perturbation finite-element method for magnetic circuits

in IET Science, Measurement & Technology (2008), 2(6), 440-446

Accurate magnetic flux distributions are calculated in magnetic circuits via a subproblem finite-element (FE) method based on a perturbation technique. An approximate FE problem considering ideal flux ... [more ▼]

Accurate magnetic flux distributions are calculated in magnetic circuits via a subproblem finite-element (FE) method based on a perturbation technique. An approximate FE problem considering ideal flux tubes is first solved. It gives the source for FE perturbation problems considering the flux tubes with their exterior regions, accounting thus for leakage fluxes, as well as for changes of material properties and shapes. The proposed technique aims to accurately quantify the gain given by each model refinement on both local fields and global quantities and to justify the usefulness of this refinement. It is also well adapted to parameterised analyses on geometrical and material data. [less ▲]

A perturbation method for the 3D finite element modeling of electrostatically driven MEMS

in Sensors (2008), 8(2), 994-1003

In this paper, a finite element (FE) procedure for modeling electrostatically actuated MEMS is presented. It concerns a perturbation method for computing electrostatic field distortions due to moving ... [more ▼]

In this paper, a finite element (FE) procedure for modeling electrostatically actuated MEMS is presented. It concerns a perturbation method for computing electrostatic field distortions due to moving conductors. The computation is split in two steps. First, an unperturbed problem (in the absence of certain conductors) is solved with the conventional FE method in the complete domain. Second, a perturbation problem is solved in a reduced region with an additional conductor using the solution of the unperturbed problem as a source. When the perturbing region is close to the original source field, an iterative computation may be required. The developed procedure offers the advantage of solving sub-problems in reduced domains and consequently of benefiting from different problem-adapted meshes. This approach allows for computational efficiency by decreasing the size of the problem. [less ▲]

A perturbation method for the 3D Finite Element Modeling

Poster (2007, May 11)

Perturbation of actin dynamics induces NF-kappa B activation in myelomonocytic cells through an NADPH oxidase-dependent pathway

in Biochemical Journal (2005), 387(Pt 2), 531-540

Although several reports showed the effect of compounds disrupting microtubules on NF-kappa B (nuclear factor kappa B) activation, nothing is known about agents perturbing actin dynamics. In the present ... [more ▼]

Although several reports showed the effect of compounds disrupting microtubules on NF-kappa B (nuclear factor kappa B) activation, nothing is known about agents perturbing actin dynamics. In the present study, we have shown that actin cytoskeleton disruption induced by actin-depolymerizing agents such as cytochalasin D and latrunculin B and actin-polymerizing compounds such as jasplakinolide induced NF-kappa B activation in myelomonocytic cells. The transduction pathway involved the I kappa B (inhibitory kappa B) kinase complex and a degradation of I kappa B alpha. We have shown that NF-kappa B activation in response to the perturbation of actin dynamics required reactive oxygen species. as demonstrated by the effect of antioxidants. Actin cytoskeleton disruption by cytochalasin D induced O-2(-) release from human monocytes, through the activation of the NADPH oxidase, as confirmed by the phosphorylation and by the membrane translocation of p47(phox). NF-kappa B activation after actin cytoskeleton disruption could be physiologically relevant during monocyte activation and/or recruitment into injured tissues, where cellular attachment, migration and phagocytosis result in cyclic shifts in cytoskeletal organization and disorganization. [less ▲]

A perturbation technique for Finite Element Modelling of Piezoelectric Vibrations in Travelling Wave Ultrasonic Motors

in Proceedings of the second international conference on advanced computational methods in engineering, ACOMEN 2002 (2002)