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A Perfectly Matched Layer for the Nonlinear Dispersive finite-element Time-Domain Method

IEEE TRANSACTIONS ON MAGNETICS 2019年第6期55卷 1-4页

作者： Abraham, David S. Giannacopoulos, Dennis D. McGill Univ Dept Elect & Comp Engn Montreal PQ H3A 0E9 Canada

A novel implementation of a perfectly matched layer (PML) is presented for the truncation of finite-element time-domain (FETD) meshes containing electrically complex materials, exhibiting any combination of linear dispersion, instantaneous nonlinearity, and dispersive nonlinearity. Based on the complex coordinate stretching formulation of the PML, the presented technique yields an artificial absorbing layer whose matching condition is independent of material parameters. Moreover, by virtue of only modifying spatial derivatives, the incorporation of the PML into existing solvers for complex media is simple and straightforward. The resulting material-independent PML is incorporated into a nonlinear dispersive method for the vector wave equation, which leverages the z transform and Newton-Raphson techniques to yield an implementation free from recursive convolutions, auxiliary differential equations, and linearizations. This permits the unprecedented truncation and attenuation of nonlinear phenomena, such as spatial and temporal solitons, within the FETD method.

关键词： Dispersive media finite-element methods nonlinear media perfectly matched layers (PMLs)

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Analysis and Reduction of Circulating Current Loss of Armature Wires in Permanent Magnet Synchronous Machines

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IEEE TRANSACTIONS ON INDUSTRY APPLICATIONS 2019年第6期55卷 5888-5896页

作者： Yamazaki, Katsumi Furuhashi, Takahiro Yui, Haiyan Ohguchi, Hideki Imamori, Satoshi Shuto, Masao Chiba Inst Technol Narashino Chiba 2750016 Japan Hitachi Ind Equipment Syst Co Ltd Tokyo 1010022 Japan Tokai Univ Hiratsuka Kanagawa 2591292 Japan Fuji Elect Co Ltd R&D Sect Hino Tokyo 1918502 Japan Fuji Elect Co Ltd Suzuka 5138633 Japan

In this article, we investigate the loss reduction of permanent magnet machines, whose armature windings consist of parallel wires. First, the impact of the loss caused by the circulating currents in the parallel armature wires is estimated by finite-element analysis. The calculated total electrical loss is compared with the experimental result of a prototype motor. The measured and calculated results are found to be in good agreement. In addition, it is revealed that the circulating armature current loss is larger than the usual copper loss, which is estimated only by the total armature current and the armature winding resistance. Next, the loss reduction by reducing the number of parallel wires is discussed. The optimal number of parallel wires is found by considering the tradeoff between the reduction of circulating current loss and increases in the other losses, such as usual copper loss and core loss.

关键词： Eddy currents finite-element methods losses permanent magnet machines

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Optimization of a Horizontal Axis HTS ZFC Levitation Bearing Using Genetic Decision Algorithms Over finite element Results

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IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 2020年第2期30卷

作者： Fernandes, Joao F. P. Costa, Antonio J. Arsenio Arnaud, Joao Univ Lisbon Inst Super Tecn IDMEC P-1649004 Lisbon Portugal

In this article, a multiobjective optimization is done to minimize the cost and volume of a horizontal axis high-temperature superconductors (HTS) levitation bearing. The optimization is done using 3-D finite-element analysis (FEA) and an equivalent magnetic permeability model for HTS bulks depending on the applied magnetic field. The use of this equivalent permeability model rather than the HTS magnetization Kim's model is required to perform the optimization process in a feasible time. The computation time for 3-D FEA with Kim's HTS model is 43.6 h and with the equivalent permeability model is 2.2 min. The equivalent permeability model is described and calibrated using experimental results from a previously developed D5 levitation bearing and is then used in the optimization process. From the cost optimization, results show that it is possible to reduce by 45.9% the cost of the levitation bearing by reducing the HTS volume by 55.4% and increasing the permanent magnet's (PM's) volume by 69.6%, while maintaining the same net lifting forces. From the volume optimization, it was possible to reduce both HTS and PM's volume by 16.2% and 22.4%, respectively, and to reduce the overall levitation bearing cost by 16.6%. From the optimization, it was verified that the solution from the cost optimization provided an increase of stability (guidance forces).

关键词： Equivalent permeability model finite-element methods high-temperature superconductors (HTS) Kim's model magnetic levitation optimization

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Multi-objective optimization of an electrode pair for electrochemotherapy: M-NSGA and μ-BIMO comparison

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INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS 2019年第Sup1期60卷 S163-S172页

作者： Di Barba, Paolo Dughiero, Fabrizio Mognaschi, Maria Evelina Sieni, Elisabetta Univ Pavia Dept Elect Comp & Biomed Engn Pavia Italy Univ Padua Dept Ind Engn Padua Italy Insubria Univ Dept Theoret & Appl Sci Via Dunant 3 I-21100 Varese Italy

In the paper, a multi-objective optimization of an electrode pair for electrochemotherapy is performed. The aim is to design the electrode pair geometry in order to obtain an effective treatment, which means a homogeneous and suitable electric field distribution. To solve this problem, two recently developed algorithms, M-NSGA and mu-BiMO, are applied.

关键词： Electric field electrochemotherapy finite-element methods optimal design

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Multi-objective optimization of an electrode pair for electrochemotherapy: M-NSGA and μ-BIMO comparison

Multi-objective optimization of an electrode pair for electr...

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15th Biennial International Workshop on Optimization and Inverse Problems in Electromagnetism (OIPE)

关键词： Electric field electrochemotherapy finite-element methods optimal design

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Analysis and Reduction of Circulating Current Loss of Armature Wires in Permanent Magnet Synchronous Machines

Analysis and Reduction of Circulating Current Loss of Armatu...

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10th Annual IEEE Energy Conversion Congress and Exposition (ECCE)

关键词： Eddy currents finite-element methods losses permanent magnet machines

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Using Gaussian process regression for efficient parameter reconstruction 33

Using Gaussian process regression for efficient parameter re...

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Conference on Metrology, Inspection, and Process Control for Microlithography XXXIII

作者： Schneider, Philipp-Immanuel Hammerschmidt, Martin Zschiedrich, Lin Burger, Sven JCMwave GmbH Bolivarallee 22 D-14050 Berlin Germany ZIB Takustr 7 D-14195 Berlin Germany

ISBN: (数字)9781510625662

ISBN: (纸本)9781510625662

Optical scatterometry is a method to measure the size and shape of periodic micro- or nanostructures on surfaces. For this purpose the geometry parameters of the structures are obtained by reproducing experimental measurement results through numerical simulations. We compare the performance of Bayesian optimization to different local minimization algorithms for this numerical optimization problem. Bayesian optimization uses Gaussian-process regression to find promising parameter values. We examine how pre-computed simulation results can be used to train the Gaussian process and to accelerate the optimization.

关键词： computational metrology optical metrology computational lithography Bayesian optimization machine learning finite-element methods nanooptics

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Strategic Dual Image Method for Non-Axisymmetric Three-dimensional Magnetic Field Problems

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IEICE TRANSACTIONS ON ELECTRONICS 2018年第1期E101C卷 52-55页

作者： Sugahara, Kengo Kindai Univ Higashiosaka Osaka 5778502 Japan

Strategic Dual Image method (SDI) for three-dimensional magnetic field problems is proposed. The basic idea of the SDI method is that the open boundary solution is in-between the Dirichlet and Neumann solutions. The relationship between the specific topology (e.g. sphere, and ellipsoid) of the boundary and the averaging weight has been discussed in the previous literature, however no discussions on the arbitrary topology. In this paper, combined with "the perturbation approach using equivalence theorem", the methodology to derive the averaging weight of Dirichlet and Neumann solutions on the arbitrary topology has been proposed. Some numerical examples are also demonstrated.

关键词： finite-element methods open boundary problem strategic dual image method

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Stabilized Reduced-Order Model of a Non-Linear Eddy Current Problem by a Gappy-POD Approach

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IEEE TRANSACTIONS ON MAGNETICS 2018年第12期54卷 1-8页

作者： Hasan, Md. Rokibul Montier, Laurent Henneron, Thomas Sabariego, Ruth V. Katholieke Univ Leuven EnergyVille Dept Elect Engn ESAT B-3001 Leuven Belgium Univ Lille HEI Arts & Metiers ParisTech L2EPCent Lille F-59000 Lille France

In this paper, a stabilized reduced-order model based on the gappy proper orthogonal decomposition (POD) technique is applied to an eddy-current problem with the non-linear material property. A classical magnetodynamic finite element formulation based on the magnetic vector potential is used as reference and starting point to build up the reduced models. The computational complexity of the non-linear problem might be reduced by the discrete empirical interpolation method-POD technique, but the eddy current effects may make this method unstable. In this paper, we propose an approach which is similar to the gappy method to successfully overcome this instability problem, while keeping the computational cost (time and memory) low.

关键词： Discrete empirical interpolation eddy currents finite-element methods gappy-proper orthogonal decomposition (POD) non-linear materials POD reduced-order models

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Impact and importance of hyperdiffusion on the spectral element method: A linear dispersion analysis

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JOURNAL OF COMPUTATIONAL PHYSICS 2018年 375卷 427-446页

作者： Ullrich, Paul A. Reynolds, Daniel R. Guerra, Jorge E. Taylor, Mark A. Univ Calif Davis Dept Land Air & Water Resources Davis CA 95616 USA Southern Methodist Univ Dept Math POB 750156 Dallas TX 75257 USA Sandia Natl Labs POB 5800MS 1320 Albuquerque NM 87185 USA

The spectral element method (SEM) is a mimetic finite element method with several properties that make it a desirable choice for numerical modeling. Although the linear dispersion properties of this method have been analyzed extensively for the case of the 1D inviscid advection equation, practical implementations of the SEM frequently employ hyperdiffusion for stabilization. As argued in this paper, hyperdiffusion has a pronounced impact on the accuracy of the discrete wave modes and the dispersive properties of the SEM. When applied with an appropriately large coefficient, hyperdiffusion is effective at removing the spectral gap and improving the stability of the 1D advection equation. This study also considers the SEM as applied to the 2D linearized shallow-water equations, where hyperdiffusion in the form of scalar diffusion, divergence damping, and vorticity damping are analyzed. To the extent possible, guidance on the choice of hyperdiffusion coefficients is provided. A brief discussion of the comparative impact of local element filtering is included. (C) 2018 Elsevier Inc. All rights reserved.

关键词： High-order Dispersion analysis Spectral-element method finite-element methods Linear gravity waves Dynamical core

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