Researcher Profile and Settings

Master

Affiliation (Master)

• Faculty of Information Science and Technology　Systems Science and Informatics　System Synthesis

Affiliation (Master)

• Faculty of Information Science and Technology　Systems Science and Informatics　System Synthesis

researchmap

Profile and Settings

Profile and Settings

• Contact Point

  igarashissi.ist.hokudai.ac.jp

• Name (Japanese)

  HAJIME

• Name (Kana)

  IGARASHI

• Name

  200901039092001174

Alternate Names

http://hbd.ist.hokudai.ac.jp/

Achievement

Research Interests

• Energy Harvesting   design optimization   Topology optimization   AI-based optimal design   computational electromagnetism   

Research Areas

• Manufacturing technology (mechanical, electrical/electronic, chemical engineering) / Electrical power engineering
• Informatics / Computational science
• Social infrastructure (civil Engineering, architecture, disaster prevention) / Safety engineering
• Social infrastructure (civil Engineering, architecture, disaster prevention) / Social systems engineering

Research Experience

• 2004/04 - Today Graduate School of Information Science, Hokkaido University Professor

Committee Memberships

• 2023/01 - Today   IEEE Sapporo Section Chair   IEEE Sapporo Section Chair
• 2007 - Today   International COMPUMAG Society   International COMPUMAG Society, Vice President

Awards

• 2024/09 電気学会 2023年電子・情報・システム部門大会企画賞
  
• 2024/05 電気学会 電気学術振興賞(著作賞)
   「電磁界解析による最適設計」森北出版 

  受賞者: 五十嵐一
• 2019/05 電気学会 電子・情報・システム部門貢献賞
   

  受賞者: 五十嵐 一
• 2017/10 日本AEM学会 功労賞
   

  受賞者: 五十嵐 一
• 2016/04 電気学会 電気学術振興賞(論文賞)
   

  受賞者: 五十嵐 一
• 2016/04 文部科学省 科学技術分野の文部科学大臣表彰科学技術賞(開発部門)
   

  受賞者: 五十嵐 一
• 2015/10 日本シミュレーション学会 論文賞
   

  受賞者: 五十嵐 一
• 2003 日本AEM学会 著作賞
   「計算電磁力学」 

  受賞者: 五十嵐 一

Published Papers

• Monte Carlo tree search applied to design of wireless power transfer system

  Shuli Yin, Kazuki Sato, Yuki Ito, Hiroaki Ota, Yoshitsugu Otomo, Hajime Igarashi

  International Journal of Applied Electromagnetics and Mechanics 1 - 13 1383-5416 2024/07/31 

  An automatic design optimization of a wireless power transfer system is performed using Monte Carlo tree search (MCTS). Several key factors, i.e., the compensation network, shapes and geometrical parameters of the coils are determined after searches, in order to achieve the high transfer efficiencies for coaxial aligned and misaligned cases. The improved Selection policy in MCTS, called first play urgency (FPU), is implemented for optimization. It proves to be a more promising technique for finding optimal solutions when the searching volume is limited, compared with the original MCTS with using the upper confidence bound applies to tree (UCB1).
• Multi-objective optimization and uncertainty quantification for inductors based on neural network

  Xiaohan Kong, Shuli Yin, Yunyi Gong, Hajime Igarashi

  COMPEL - The International Journal for Computation and Mathematics in Electrical and Electronic Engineering 43 (4) 890 - 903 0332-1649 2024/07/30 

  Purpose: The prolonged training time of the neural network (NN) has sparked considerable debate regarding their application in the field of optimization. The purpose of this paper is to explore the beneficial assistance of NN-based alternative models in inductance design, with a particular focus on multi-objective optimization and uncertainty analysis processes. Design/methodology/approach: Under Gaussian-distributed manufacturing errors, this study predicts error intervals for Pareto points and select robust solutions with minimal error margins. Furthermore, this study establishes correlations between manufacturing errors and inductance value discrepancies, offering a practical means of determining permissible manufacturing errors tailored to varying accuracy requirements. Findings: The NN-assisted methods are demonstrated to offer a substantial time advantage in multi-objective optimization compared to conventional approaches, particularly in scenarios where the trained NN is repeatedly used. Also, NN models allow for extensive data-driven uncertainty quantification, which is challenging for traditional methods. Originality/value: Three objectives including saturation current are considered in the multi-optimization, and the time advantages of the NN are thoroughly discussed by comparing scenarios involving single optimization, multiple optimizations, bi-objective optimization and tri-objective optimization. This study proposes direct error interval prediction on the Pareto front, using extensive data to predict the response of the Pareto front to random errors following a Gaussian distribution. This approach circumvents the compromises inherent in constrained robust optimization for inductance design and allows for a direct assessment of robustness that can be applied to account for manufacturing errors with complex distributions.
• Synthesis of Extended Cauer-Equivalent Circuit of Magnetic Components Considering Multiple Resonant Peaks

  Yuki Sato, Hirokazu Matsumoto, Hajime Igarashi, Kenji Kawano

  IEEJ Transactions on Fundamentals and Materials 144 (6) 214 - 221 0385-4205 2024/06/01 

  This paper introduces an extended Cauer-equivalent circuit model of magnetic components that can represent both eddy-current effects and capacitive properties. As this model considers the skin and proximity effects of the winding as well as the parasitic capacitance, it is accurate from DC to more than 500 MHz, even with multiple resonances. The resonant characteristics are expressed by RLC series circuits in parallel with a Cauer circuit representing the inductive part. The proposed circuit is applied to two test inductors, and then the effectiveness of this method is verified.
• Visual Interpretation of Topology Optimization Results Based on Deep Learning

  Hayaho Sato, Hajime Igarashi

  IEEE Transactions on Magnetics 60 (3) 1 - 4 0018-9464 2024/03/01 [Refereed][Not invited]
   

  In this study, an approach was proposed to interpret the shapes of electric motors obtained by topology optimization (TO). A convolutional neural network (CNN) model was trained on motor images and used to predict the degree of influence of local structures of motors on their characteristics. This prediction was obtained as heatmaps for visualizing the importance of each local structure. The proposed method was applied to a permanent magnet motor model. The proposed method facilitated successful visualization of the degree of influence on average torque, torque ripple, and mechanical stress. This was validated by comparing the obtained predictions with finite element analysis results. In addition, the proposed method allowed us to improve the motor characteristics through visualization. Therefore, this approach can improve the mechanical stress resistance while maintaining the torque characteristics.
• A Comprehensive Optimal Design of Inductors Using Monte Carlo Tree Search

  Shuli Yin, Hayaho Sato, Hajime Igarashi

  IEEE Transactions on Magnetics 60 (3) 0018-9464 2024/03/01 [Refereed][Not invited]
   

  This article presents a strategy of optimizing inductors with non-linear properties, using Monte Carlo tree search (MCTS). Compared with the existing optimization tools, the proposed method can simultaneously optimize global configuration, such as material, number of turns and winding arrangement, and local geometry. It indicates that the strategy statistically provides a best solution from global and local aspects after iterations with different lengths of chromosomes, which is challenging in conventional optimization techniques. The covariance matrix adaptation evolution strategy (CMA-ES) is used to solve the parametric optimization. For validation, the optimizations on 2-D inductors are performed. The proposed method is very suitable for the optimization of devices with possibly different global configurations. The most notable originality of this work is in the proposal of an inherited search for design targets with different emphases, suggesting that using an inherited search from the previous search history can make it easier to find the optimal solution.
• Topology Optimization of a Surface Permanent Magnet Motor With High Torque Density

  Shogo Hayashi, Manabu Yatsurugi, Yoshihisa Kubota, Shingo Soma, Hajime Igarashi

  IEEE Transactions on Magnetics 60 (3) 0018-9464 2024/03/01 [Refereed]
   

  This paper introduces a topology optimization method for a surface permanent magnet (SPM) motor with high torque density suitable for air mobility. The proposed method can be used to determine the material distribution and magnetization direction in PMs to maximize the torque density at a constant current. The torque performance of the optimized motor is superior to that of a conventional motor with a Halbach array, whose magnetization varies linearly along the circumferential direction. The novel optimized motor has a triangular magnetic material on the rotor surface and an air region inside the rotor.
• Parameter and Topology Optimizations for Wireless Power Transfer Device Considering Magnetic and Circuit Properties

  Yoshitsugu Otomo, Kazuki Sato, Ken Onozaka, Hajime Igarashi

  IEEE Transactions on Magnetics 60 (3) 1 - 5 0018-9464 2024/03/01 [Refereed]
   

  This paper proposes a novel optimization method to design the transmitting and receiving coils of a wireless power transfer (WPT) device considering its magnetic and circuit properties. In the proposed optimization, the coil shapes are determined by parameter optimization for manufacturability, whereas the magnetic core shapes introduced near them are determined by topology optimization. The power transfer efficiencies of the optimized WPT device are evaluated using the SPICE simulation considering the coupling with an electronic circuit. The circuit parameters of the optimized coils are computed using the homogenization-based finite element method, which can effectively evaluate the eddy current loss in the coil windings. It is shown that the optimized WPT device has a power transfer efficiency higher than 90 % even when there is a misalignment.
• Loss Evaluation of Magnetic Devices Using Cauer Equivalent Circuit Identified from Input Impedance

  Qiao Liu, Y. Uehara, N. Terauchi, N. Sato, Y. Matsuda, M. Nagano, Hajime Igarashi

  IEEE Transactions on Magnetics 60 (3) 1 - 5 0018-9464 2024/03/01 [Refereed][Not invited]
   

  This study proposes a method for analyzing magnetic devices such as inductors and wireless power-transfer (WPT) systems based on a Cauer equivalent circuit. The circuit parameters are determined based on computed or measured input impedance. It is possible to obtain dynamic response and eddy-current loss in the time domain for arbitrary drive voltage waveforms from the synthesized Cauer equivalent circuit. Magnetic saturation in the core of an inductor could be accurately represented using the Cauer circuit. Moreover, the transient response of a WPT device is shown to be modeled by the Cauer circuit, including the effect of misalignment.
• Topology Optimization of Microstrip Lines With Experimental Validation

  Takuto Jibiki, Takeshi Kawasaki, Masahiro Tanomura, Hajime Igarashi

  IEEE Transactions on Magnetics 60 (3) 0018-9464 2024/03/01 [Refereed][Not invited]
   

  This paper presents the topology optimization of a microstrip line to obtain a novel structure with desired characteristics. The line shape is represented by the weighted sum of normalized Gaussian functions whose weighting coefficients are determined by a stochastic algorithm. The optimized filter characteristics are compared with measured results as well as with those obtained by a conventional design method. A novel structure is shown to have advantages over conventional methods in terms of circuit length and other characteristics. Furthermore, a microwave coupler was successfully optimized by the proposed method, demonstrating its versatility.
• Homogenized Finite Element Analysis for Multi-Turn Coils Considering Parasitic Capacitances

  Yuki Sato, Daisuke Ishii, Hirokazu Matsumoto, Hajime Igarashi

  IEEE Transactions on Magnetics 60 (3) 1 - 1 0018-9464 2024/03/01 [Refereed]
   

  This study presents a novel homogenized finite element method that can consider parasitic capacitances of the multi-turn coils. In this method, a total capacitance, describing the parasitic capacitances, is parallel to the homogenized region, and the resonant peak is identified only by solving the electro- and magneto-static finite element analysis. The proposed method is applied to the solenoid and planar coil models, and it is confirmed that the impedance characteristics including the resonant peaks can be represented. Moreover, the computing cost is shown to be significantly lower than that of the conventional full-wave finite element analysis.
• Generalization Performance in Predicting Torque Characteristics Using Convolutional Neural Network and Stator Magnetic Flux

  Kazuhisa Iwata, Hidenori Sasaki, Hajime Igarashi, Daisuke Nakagawa, Tomoya Ueda

  IEEE Transactions on Magnetics 60 (3) 1 - 4 0018-9464 2024/03/01 [Refereed][Not invited]
   

  This study proposes a novel approach using convolutional neural networks (CNNs) to predict the torque characteristics of an interior permanent magnet (IPM) motor. The proposed method allows CNNs to predict the average torque and torque amplitude under various magnet configurations using the magnetic flux density distribution of the stator core. The proposed method, compared with methods trained only on the magnetic flux density distributions of the rotor core, improves the generalization performance in predicting torque characteristics. This significantly reduces the training data. In addition, the topology optimization (TO) time using the proposed method is reduced by 45% compared with the conventional method that only utilizes the finite element method (FEM).
• Parameter and Topology Optimization Method for IPM Motors using Multimodal Neural Network

  Kazuhisa Iwata, Hidenori Sasaki, Hajime Igarashi, Daisuke Nakagawa, Tomoya Ueda

  CEFC 2024 - 21st IEEE Biennial Conference on Electromagnetic Field Computation 2024 

  This study proposes a novel parameter and topology optimization method for an interior permanent magnet synchronous motor using a multimodal neural network. The optimized shape obtained by the proposed method improves the manufacturability compared to the conventional method. In addition, the computational time of the optimization using the proposed method is reduced by about 99.9% compared to the optimization using only the finite element method.
• Multi-objective optimization of permanent magnet motors using deep learning and CMA-ES

  Ryosuke Mikami, Hayaho Sato, Shogo Hayashi, Hajime Igarashi

  International Journal of Applied Electromagnetics and Mechanics 73 (4) 255 - 264 1383-5416 2023/12/14 [Refereed][Not invited]
   

  This paper proposes a multi-objective optimization method for permanent magnet motors using a fast optimization algorithm, Covariance Matrix Adaptation Evolution Strategy (CMA-ES), and deep learning. Multi-objective optimization with topology optimization is effective in the design of permanent magnet motors. Although CMA-ES needs fewer population size than genetic algorithm for single objective problems, this is not evident for multi-objective problems. For this reason, the proposed method generates training data by solving the single-objective optimization multiple times using CMA-ES, and constructs a deep neural network (NN) based on the data to predict performance from motor images at high speed. The deep NN is then used for fast solution of multi-objective optimization problems. Numerical examples demonstrate the effectiveness of the proposed method.
• トポロジー最適化を用いた統合設計

  五十嵐, 一, 佐藤 駿輔

  計算工学 28 (4) 4681 - 4684 2023/11 [Refereed][Invited]
  
• 総説 : AI応用の動向と今後の展望—特集 人工知能が広げるモータ設計・モータドライブ技術の可能性

  五十嵐 一

  電気学会誌 = The journal of the Institute of Electrical Engineers of Japan 電気学会 143 (10) 624 - 627 1340-5551 2023/10 [Refereed][Invited]
  
• Multi-objective topology design optimization combined with robust optimization

  Akito Maruo, Norihiko Itani, Ayano Hasome, Takashi Yamazaki, Hajime Igarashi

  Journal of Advanced Mechanical Design, Systems and Manufacturing 17 (3) 2023/06 [Refereed]
   

  Topology optimization (TO), which is a design optimization technique that does not require design parameters, has been attracting attention. TO has a high degree of freedom and can obtain a novel design shape suitable for desired purposes. However, the characteristics of the obtained design shape may be greatly damaged due to uncertainty such as variations in material properties. Also, when multi-objective optimization for TO is considered, an increase in the calculation load becomes a major problem. In this study, as a method for efficiently conducting multiobjective robust TO, multi-objective robust solutions can be obtained by using a single-objective robust covariance matrix adaptation evolution strategy and the hybrid method of robust genetic algorithm and multi-objective robust design optimization. The proposed method was applied to design problems of magnetic shields, and obtaining a wide range Pareto front with robustness that cannot be obtained by conventional methods is possible.
• Time-Domain Homogenized Finite Eddy Current Analysis Using Recursive Convolution Method

  Yuki Sato, Shingo Hiruma, Hajime Igarashi, Hirokazu Matsumoto

  IEEE Transactions on Magnetics 59 (5) 0018-9464 2023/05/01 [Refereed]
   

  This article presents a novel method for effectively and accurately performing time-domain homogenized finite-element analysis of multi-turn coil windings. In this method, the macroscopic complex permeability is represented by a partial fraction form, and then, the inverse Laplace transformation is performed using the recursive convolution (RC) method. The proposed method is approximately $100\times $ faster than the conventional finite-element analysis, with good agreement between the obtained results. Moreover, the results obtained by the proposed method were also in good agreement with those obtained by measurement.
• Multi-Objective Automatic Design of Permanent Magnet Motor Using Monte Carlo Tree Search

  Sato, Hayaho, Igarashi, Hajime

  IEEE transactions on magnetics 59 (5) 8201304  0018-9464 2023/05/01 [Refereed]
   

  This study proposes a novel multi-objective design method based on Monte Carlo tree search (MCTS) for the design of permanent magnet (PM) motors. The global configurations that define the entire structure are represented by nodes in a tree structure. After MCTS is performed to select a route extending from the root to leaf node, multi-objective topology optimization (TO) is performed at the leaf node to determine the detailed shape, considering a trade-off relationship among objective functions. The novelty of this work lies in the integration of MCTS with multi-objective TO where the score of a node is provided by the number of Pareto solutions obtained by selecting that node. This enables the scoring of nodes and the determination of the node selection criterion. The proposed method is applied to the multi-objective optimization of a PM motor with respect to average torque, and either torque ripple or iron loss. The proposed method successfully obtained Pareto solutions, which comprise various global configurations and shapes.
• Topology-Parameter Hybrid Optimization of Skewed Permanent Magnet Motor

  Shogo Hayashi, Yoshihisa Kubota, Shingo Soma, Satoyoshi Oya, Hajime Igarashi

  IEEE Transactions on Magnetics 59 (5) 0018-9464 2023/05/01 [Refereed]
   

  In this study, we present a topology-parameter hybrid optimization of a permanent magnet motor with a step-skewed rotor. This optimization simultaneously performed topology optimization (TO) of the core shape and parameter optimization (PO) of the skew angle. Simultaneous optimization provides optimized motors that are superior to those obtained by parameter, topology, and sequential optimizations. Moreover, the optimized shape was shown to be robust with respect to variations in the skew angle.
• Fast Topology Optimization for PM Motors Using Variational Autoencoder and Neural Networks With Dropout

  Sato, Hayaho, Igarashi, Hajime

  IEEE transactions on magnetics 59 (5) 8200904  0018-9464 2023/05/01 [Refereed]
   

  This study proposes a novel topology optimization (TO) method for permanent magnet (PM) motors based on a variational autoencoder (VAE) and a neural network (NN). The VAE is trained to embed various shapes generated from the TO into the latent space. The NN is trained to predict the characteristics of the PM motor from its latent representation derived using the VAE. After training, TO is performed in the latent space based on the prediction using the NN. We adopt the Monte Carlo dropout to maintain prediction reliability using the NN during optimization, where prediction deviation is evaluated and used to eliminate unreliable solutions. The proposed method yields Pareto solutions within 80 s in a single-thread CPU machine, which is considerably faster than numerical analysis-based optimization, such as finite-element analysis.
• Equivalent circuit of high frequency inductor to consider eddy currents and resonance

  Qiao Liu, Yoshitsugu Otomo, Yunyi Gong, Hajime Igarashi

  International Journal of Applied Electromagnetics and Mechanics 71 S275 - S282 1383-5416 2023/04/14 [Refereed]
   

  The resistance and inductance of an inductor working at high frequencies depend on frequency because of eddy currents caused by the skin and proximity effects. In addition, the stray capacitance among winding coils would give significant influence. This paper proposes an equivalent circuit model which can consider the displacement and eddy currents simultaneously in frequency and time domain. In the proposed circuit model, the capacitance and complex inductance are determined by solving electrostatic and magnetostatic equations with finite element method (FEM). It is shown that the input impedance of an air-core coil is consistent with that computed by FEM at low frequencies. Moreover, the former is shown to be consistent with the measured result.
• Parameter-topology hybrid optimization of electric motor with multiple permanent magnets

  Shogo Hayashi, Hajime Igarashi

  International Journal of Applied Electromagnetics and Mechanics 71 S245 - S255 1383-5416 2023 [Refereed]
   

  A hybrid optimization method that combines parameter optimization (PO) with topology optimization (TO) is proposed for the design of a permanent magnet (PM) motor. The PM shape, configuration, and flux barrier topology were simultaneously optimized using the proposed method. The conventional hybrid method that deals with a single PM is effectively extended to deal with multiple PMs parameterized by several geometrical parameters. The use of this extension makes it possible to search for the optimal rotor structure of the multiple-PM motor, which is widely used in electric vehicles. The results obtained by the proposed method are shown superior over those obtained by conventional method. The rotor structure with double-U shaped PMs with small flux barriers near the airgap was obtained by the optimization.
• Robust Covariance Matrix Adaptation Evolution Strategy: Optimal Design of Magnetic Devices Considering Material Variation

  Akito Maruo, Hajime Igarashi

  IEEE Access 2023 [Refereed]
   

  Uncertainties caused by material variation can significantly impair the characteristics of devices. Therefore, it is important to design devices whose performance is not significantly damaged even when material variations occur. Robust optimization seeks for the optimal solutions that are robust to fluctuations due to uncertainties caused by material variation, geometrical variation due to assembly tolerances, and changes in physical properties over time in real-world problems. However, naive robust optimization requires iterative calculations to compute the expected values, which need a huge computational burden. This paper introduces a novel robust optimization method for magnetic devices using the covariance matrix adaptation evolution strategy (CMA-ES). In this method, called RCMA-ES (robust CMA-ES), the expected value of the objective function is evaluated using the local average of neighboring individuals without increasing the computation cost. For validation, RCM-ES and robust genetic algorithm (RGA), one of the robust optimization methods without increasing the computational load, was applied to the topology optimization of a magnetic shield and actuator, considering the uncertainty in the BH characteristics. RCM-ES was demonstrated to be particularly more effective for topology optimization with a large number of dimensions compared to RGA and provides robust optimal shapes that are insensitive to variations in BH characteristics.
• Gradient Coil Design Method Specifically for Permanent-Magnet-Type Low Field Portable MRI Brain Scanner.

  Xiaohan Kong, Zheng Xu 0007, Sheng Shen, Jiamin Wu, Yucheng He, Liang Xuan, Hajime Igarashi

  IEEE Trans. Instrum. Meas. 72 1 - 12 2023 [Refereed]
  
• Unified design using Monte Carlo tree searcg and hybridized topology-parameter optimization

  Hayaho Sato, Hajime Igarashi

  日本AEM学会誌 30 (4) 384 - 389 2022/12 [Refereed][Invited]
  
• What AI can do for you: for researchers who plan to apply it to their study

  Hajime Igarashi

  日本AEM学会誌 30 (4) 365 - 372 2022/12 [Refereed][Invited]
  
• Study on sequence problem optimization using variation-robust multi-objective optimization genetic algorithm

  Takashi YAMAZAKI, Akito MARUO, Ayano HASOME, Jun TANIGUCHI, Hajime IGARASHI

  Journal of Advanced Mechanical Design, Systems, and Manufacturing 16 (5) No.22-00102  2022/10 [Refereed][Not invited]
  
• Topology Optimization of Electromagnetic Devices Using Digital Annealer

  Akito Maruo, Takeshi Soeda, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 58 (9) 0018-9464 2022/09 [Refereed]
   

  Topology optimization (TO) has been formulated as a quadratic unconstrained binary optimization (QUBO) problem that can be solved by Digital Annealer (DA) and quantum computers, which can realize massive parallelization. It is shown that the 3-D TO of a permanent magnet (PM), with 600 unknowns, is successfully performed by the DA with the aid of the finite element method (FEM) for field computations. Moreover, it is shown to perform TO of a magnetic core, with 758 unknowns, in such a way that the QUBO and field problems are iteratively solved to determine the optimal solution in which the magnetic field and optimal core structure are self-consistent.
• Topology Optimization of Permanent Magnet Synchronous Motor Considering the Control System

  Shogo Hayashi, Yoshihisa Kubota, Shingo Soma, Makoto Ohtani, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 58 (9) 0018-9464 2022/09 [Refereed]
   

  This article proposes a novel topology optimization approach for permanent magnet synchronous motors (PMSMs) driven by a pulsewidth modulation (PWM) current control system operating in different modes such as maximum torque per ampere (MTPA) and weakening flux controls. The cost function consits of iron and copper losses, which are computed by considering the spatial and time harmonics in the current generated under these conditions. It is demonstrated that the total loss of the optimized model is reduced compared with that of the conventional model in the operating region.
• Automatic Design of PM Motor Using Monte Carlo Tree Search in Conjunction With Topology Optimization

  Hayaho Sato, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 58 (9) 0018-9464 2022/09 [Refereed]
   

  A novel automatic design method for permanent magnet (PM) motors using a Monte Carlo tree search is presented. The optimal motor structures are determined through a tree search, in which the motors with different numbers of poles, current phase angles, PM configurations, and numbers of PMs are simultaneously considered. At the leaf nodes, parameter and topology optimizations are performed to obtain the optimal material shape and distribution. The proposed method was applied to the optimization of a 24-slot motor. It was shown to be effective in finding the optimal motor structure and geometry to maximize the average torque while considering iron loss. The proposed method can be applied not only to the design of PM motors but also to many types of electric apparatus and other systems.
• Neural Network for Both Metal Object Detection and Coil Misalignment Prediction in Wireless Power Transfer

  Yunyi Gong, Yoshitsugu Otomo, Hajime Igarashi

  IEEE Transactions on Magnetics 58 (9) 1 - 4 0018-9464 2022/09 [Refereed]
  
• Fast Multi-Objective Optimization of Electromagnetic Devices Using Adaptive Neural Network Surrogate Model

  Hayaho Sato, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 58 (5) 0018-9464 2022/05 [Refereed]
   

  This article presents a fast population-based multi-objective optimization of electromagnetic devices using an adaptive neural network (NN) surrogate model. The proposed method does not require any training data or construction of a surrogate model before the optimization phase. Instead, the NN surrogate model is built from the initial population in the optimization process, and then it is sequentially updated with high-ranking individuals. All individuals were evaluated using the surrogate model. Based on this evaluation, high-ranking individuals are reevaluated using high-fidelity electromagnetic field computation. The suppression of the execution of expensive field computations effectively reduces the computing costs. It is shown that the proposed method works two to four times faster, maintaining optimization performance than the original method that does not use surrogate models.
• Direct Inverse Modeling for Electromagnetic Components Using Gaussian Kernel Regression

  Yuki Sato, Kenji Kawano, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 58 (5) 0018-9464 2022/05 [Refereed]
   

  This article proposes a novel direct inverse modeling (DIM) of electromagnetic (EM) devices using Gaussian kernel regression. In this method, the nonlinear multivariate relationship between design and electrical properties is represented by the Gaussian kernels. Once the regression function is built, the device parameters that lead to the required electrical properties can be directly computed using the Newton method. It is shown that the proposed DIM can find the multiple solutions in case of both 2-D and 3-D inductor design with less computing cost compared with the conventional modeling method.
• Topology optimization of magnetic cores for WPT using the geometry projection method

  Yoshitsugu Otomo, Hajime Igarashi

  COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING 41 (3) 889 - 899 0332-1649 2022/04 [Refereed]
   

  Purpose The purpose of this study is to search for an optimal core shape that is robust against misalignment between the transmitting and receiving coils of the wireless power transfer (WPT) device. During the optimization process, the authors maximize the coupling coefficients while minimizing the leakage flux around the coils to ensure the safety of the WPT device. Design/methodology/approach In this study, a novel topology optimization method for WPT devices using the geometry projection method is proposed to optimize the magnetic core shape. This method facilitates the generation of bar-shaped magnetic cores because the material distribution is represented by a set of elementary bars. Findings It is shown that an optimized core shape, which is obtained through topology optimization, effectively increases the net magnetic flux interlinked with the receiving coil and outperforms the conventional core. Originality/value In the previous topology optimization method, the material distribution is represented by a linear combination of Gaussian functions. However, this method does not usually result in bar-shaped cores, which are widely used in WPT. In this study, the authors propose a novel topology optimization method for WPT devices using geometry projection that is used in structural optimization, such as beam and cantilever shapes.
• Deep learning-based surrogate model for fast multi-material topology optimization of IPM motor

  Hayaho Sato, Hajime Igarashi

  COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING 41 (3) 900 - 914 0332-1649 2022/04 [Refereed]
   

  Purpose This paper aims to present a deep learning-based surrogate model for fast multi-material topology optimization of an interior permanent magnet (IPM) motor. The multi-material topology optimization based on genetic algorithm needs large computational burden because of execution of finite element (FE) analysis for many times. To overcome this difficulty, a convolutional neural network (CNN) is adopted to predict the motor performance from the cross-sectional motor image and reduce the number of FE analysis. Design/methodology/approach To predict the average torque of an IPM motor, CNN is used as a surrogate model. From the input cross-sectional motor image, CNN infers dq-inductance and magnet flux to compute the average torque. It is shown that the average torque for any current phase angle can be predicted by this approach, which allows the maximization of the average torque by changing the current phase angle. The individuals in the multi-material topology optimization are evaluated by the trained CNN, and the limited individuals with higher potentials are evaluated by finite element method. Findings It is shown that the proposed method doubles the computing speed of the multi-material topology optimization without loss of search ability. In addition, the optimized motor obtained by the proposed method followed by simplification for manufacturing is shown to have higher average torque than a reference model. Originality/value This paper proposes a novel method based on deep learning for fast multi-material topology optimization considering the current phase angle.
• Prediction of IPM Machine Torque Characteristics Using Deep Learning Based on Magnetic Field Distribution

  Hidenori Sasaki, Yuki Hidaka, Hajime Igarashi

  IEEE Access 10 60814 - 60822 2022 [Refereed]
  
• Error Estimator for Cauer Ladder Network Representation

  Shingo Hiruma, Stephane Clenet, Hajime Igarashi, Thomas Henneron

  IEEE Transactions on Magnetics 1 - 1 0018-9464 2022 [Refereed]
  
• Fast Time-Domain Analysis of Darwin Model of Maxwell’s Equations using Arnoldi-based Model Order Reduction

  Shingo Hiruma, Hajime Igarashi

  IEEE Transactions on Magnetics 1 - 1 0018-9464 2022 [Refereed]
  
• 2.5-D Multi-Phase Topology Optimization of Permanent Magnet Motor Using Gaussian Basis Function

  Yoshitsugu Otomo, Hajime Igarashi, Tomohiro Sato, Yoshihisa Suetsugu, Eiji Fujioka

  IEEE Transactions on Magnetics 58 (9) 1 - 1 0018-9464 2022 [Refereed]
  
• Prediction of Current-dependent Motor Torque Characteristics Using Deep Learning for Topology Optimization

  Taiga Aoyagi, Yoshitsugu Otomo, Hajime Igarashi, Hidenori Sasaki, Yuki Hidaka, Hideaki Arita

  IEEE Transactions on Magnetics 58 (9) 1 - 1 0018-9464 2022 [Refereed]
  
• Machine Learning Based Metal Object Detection for Wireless Power Transfer Using Differential Coils

  Yunyi Gong, Yoshitsugu Otomo, Hajime Igarashi

  JOURNAL OF ADVANCED SIMULATION IN SCIENCE AND ENGINEERING 9 (1) 20 - 29 2188-5303 2022 [Refereed]
   

  This paper presents the machine learning-based detection of foreign metal object for the wireless power transfer device including differential coils. To test the proposed method, the differential voltages are computed using finite element method for about 1500 cases with and without an aluminum cylinder at driving frequency of 85 kHz considering misalignment between the primal and secondary coils. It has been shown that gradient boosting decision tree and random forests classifier have the accuracy over 90% when input voltages and differential voltages are inputted together.
• Design Optimization Based on Electromagnetism and Artificial Intelligence (AI) [II・Finish]: Deep Learning and Monte Carlo Tree Search

  五十嵐一, 佐々木秀徳

  電子情報通信学会誌 105 (2) 0913-5693 2022 [Refereed][Invited]
  
• Design Optimization Based on Electromagnetism and Artificial Intelligence (AI) [I]: Topology Optimization

  五十嵐一, 伊藤桂一

  電子情報通信学会誌 105 (1) 0913-5693 2022 [Refereed][Invited]
  
• Analysis of Litz Wire Losses Using Homogenization-Based FEM

  Yoshitsugu Otomo, Hajime Igarashi, Hiroyuki Sano, Takashi Yamada

  IEEE TRANSACTIONS ON MAGNETICS 57 (8) 0018-9464 2021/08 [Refereed]
   

  This article proposes a novel analysis method for the losses in a litz wire considering the circulating and eddy currents. In the proposed method, the macroscopic complex permeability is introduced to evaluate the eddy current loss owing to the proximity effect. Homogenization-based finite element analysis using the macroscopic complex permeability can effectively compute the proximity effect loss. The loss owing to the circulating currents is evaluated by solving the corresponding circuit equation. It is shown that the eddy current loss is dominant for the solenoidal and spiral coils without magnetic cores because of the uniform magnetic field distribution along the wire. Moreover, the magnetic reactors in which the circulating current loss cannot be ignored are analyzed using the proposed method. It is shown that the losses computed by the proposed method agree well with the measured results.
• Topology Optimization Using Gabor Filter: Application to Synchronous Reluctance Motor

  Yoshitsugu Otomo, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 57 (6) 8203004  0018-9464 2021/06 [Refereed]
   

  This article proposes a novel topology optimization method using the Gabor filter, which is widely used in the field of image processing. The proposed method is applied to the optimization of a synchronous reluctance motor; its average torque is maximized, and simultaneously, the torque ripple is minimized. It is shown that the proposed method results in a motor with thin layer-shaped flux barriers, which achieves a better torque performance in comparison with a conventional model and a motor optimized using normalized Gaussian network (NGnet).
• Synthesis of a cauer equivalent circuit for electric devices from computed and measured data

  Yoshitsugu Otomo, Hajime Igarashi

  IEEE Transactions on Power Electronics 36 (4) 4513 - 4521 0885-8993 2021/04 [Refereed][Not invited]
   

  This article proposes a method for modeling electric devices based on a Cauer circuit whose circuit parameters are directly determined from measured or computed data using the adjoint variable method. It has been shown that electric devices that are governed by the quasi-static Maxwell's equation can be modeled by the Cauer circuit. From the synthesized Cauer circuit, eddy current losses can be evaluated for a wide frequency range. Moreover, it can be embedded into a circuit simulator to perform the time-domain analysis. It is shown that the Cauer circuit whose parameters are identified using the proposed method works better for a simple numerical model than that whose parameters are identified using a genetic algorithm. Moreover, the Cauer equivalent circuit of a reactor and a power inductor is synthesized from the measured data using the proposed method. It is shown that the input impedance of the reactor and power inductor is well approximated by the Cauer circuit over the frequency domain of interest.
• Topology optimization of magnetic cores for WPT using the geometry projection method

  Yoshitsugu Otomo, Hajime Igarashi

  COMPEL - The International Journal for Computation and Mathematics in Electrical and Electronic Engineering 0332-1649 2021 [Refereed]
   

  Purpose: The purpose of this study is to search for an optimal core shape that is robust against misalignment between the transmitting and receiving coils of the wireless power transfer (WPT) device. During the optimization process, the authors maximize the coupling coefficients while minimizing the leakage flux around the coils to ensure the safety of the WPT device. Design/methodology/approach: In this study, a novel topology optimization method for WPT devices using the geometry projection method is proposed to optimize the magnetic core shape. This method facilitates the generation of bar-shaped magnetic cores because the material distribution is represented by a set of elementary bars. Findings: It is shown that an optimized core shape, which is obtained through topology optimization, effectively increases the net magnetic flux interlinked with the receiving coil and outperforms the conventional core. Originality/value: In the previous topology optimization method, the material distribution is represented by a linear combination of Gaussian functions. However, this method does not usually result in bar-shaped cores, which are widely used in WPT. In this study, the authors propose a novel topology optimization method for WPT devices using geometry projection that is used in structural optimization, such as beam and cantilever shapes.
• Sensorless metal object detection for wireless power transfer using machine learning

  Yunyi Gong, Yoshitsugu Otomo, Hajime Igarashi

  COMPEL - The International Journal for Computation and Mathematics in Electrical and Electronic Engineering 0332-1649 2021 [Refereed]
   

  Purpose: This study aims to realize a sensorless metal object detection (MOD) using machine learning, to prevent the wireless power transfer (WPT) system from the risks of electric discharge and fire accidents caused by foreign metal objects. Design/methodology/approach: The data constructed by analyzing the input impedance using the finite element method are used in machine learning. From the loci of the input impedance of systems, the trained neural network (NN), support vector machine and naive Bayes classifier judge if a metal object exists. Then the proposed method is tested by experiments too. Findings: In the test using simulated data, all of the three machine learning methods show high accuracy of over 80% for detecting an aluminum cylinder. And in the experimental verifications, the existence of an aluminum cylinder and empty can are successfully identified by a NN. Originality/value: This work provides a new sensorless MOD method for WPT using three machine learning methods. And it shows that NNs obtain high accuracy than the others in both simulated and experimental verifications.
• Deep learning-based surrogate model for fast multi-material topology optimization of IPM motor

  Hayaho Sato, Hajime Igarashi

  COMPEL - The International Journal for Computation and Mathematics in Electrical and Electronic Engineering 0332-1649 2021 [Refereed]
   

  Purpose: This paper aims to present a deep learning–based surrogate model for fast multi-material topology optimization of an interior permanent magnet (IPM) motor. The multi-material topology optimization based on genetic algorithm needs large computational burden because of execution of finite element (FE) analysis for many times. To overcome this difficulty, a convolutional neural network (CNN) is adopted to predict the motor performance from the cross-sectional motor image and reduce the number of FE analysis. Design/methodology/approach: To predict the average torque of an IPM motor, CNN is used as a surrogate model. From the input cross-sectional motor image, CNN infers dq-inductance and magnet flux to compute the average torque. It is shown that the average torque for any current phase angle can be predicted by this approach, which allows the maximization of the average torque by changing the current phase angle. The individuals in the multi-material topology optimization are evaluated by the trained CNN, and the limited individuals with higher potentials are evaluated by finite element method. Findings: It is shown that the proposed method doubles the computing speed of the multi-material topology optimization without loss of search ability. In addition, the optimized motor obtained by the proposed method followed by simplification for manufacturing is shown to have higher average torque than a reference model. Originality/value: This paper proposes a novel method based on deep learning for fast multi-material topology optimization considering the current phase angle.
• Fast Analysis of Electric Motor Properties using Interpolation-type Model Order Reduction

  Sakamoto Hiroki, Hajime Igarashi

  IEEJ Transactions on Industry Applications 一般社団法人 電気学会 141 (2) 193 - 198 0913-6339 2021 [Refereed][Not invited]
   

  This paper proposes simplified model order reduction for the fast dynamic simulation of electric motors. In this method, magnetic fields expressed by reduced variables are stored into memory and restored using interpolation in the current-state space to enable the properties of an electric motor to be computed fast. It is shown that the iron losses considering higher harmonics are computed accurately and effectively usingthe proposed method. Moreover, the proposed method is successfully coupled with flux-based circuit equations.

• Novel Hybridization of Parameter and Topology Optimizations: Application to Permanent Magnet Motor

  Shingo Hiruma, Makoto Ohtani, Shingo Soma, Yoshihisa Kubota, Hajime Igarashi

  IEEE Transactions on Magnetics 0018-9464 2021 [Refereed][Not invited]
   

  This paper introduces novel hybridization of parameter optimization (PO) and topology optimization (TO) methods. The proposed method is applied to the optimization of a permanent magnet motor. The magnet shape and topology of the flux barrier of the rotor core are optimized by performing PO and TO simultaneously. In the optimization, automatic mesh generation is adopted to improve the resolution of the shape representation. It is shown that the increase in the average torque resulting from the proposed hybrid optimization is larger than that obtained by the conventional TO in which only the topology of the flux barrier is optimized. The decomposition of the total torque to the magnet and reluctance torques suggests that the reluctance torque is effectively generated in the rotor optimized by the proposed method.
• Explainable Deep Neural Network for Design of Electric Motors

  Hidenori Sasaki, Yuki Hidaka, Hajime Igarashi

  IEEE Transactions on Magnetics 57 (6) 0018-9464 2021 [Refereed][Not invited]
   

  This study presents a novel two-step optimization method that incorporates explainable neural networks into topology optimization. The deep neural network (DNN) is trained to infer the torque performance from the input image of the motor cross-section. The sensitive region that has a significant influence on the average torque is extracted using gradient-weighted class activation mapping (Grad-CAM) constructed from the DNN. Then, the optimization with respect to the torque ripple is performed only in the incentive region with little influence on the average torque. The proposed method is shown to increase the average torque of an Interior Permanent Magnet (IPM) motor by 14% and reduce torque ripple by 79% compared to the original model.
• Three-dimensional Analysis of Soft Magnetic Composite Using Discrete Element Method in Frequency Domain

  Hayaho Sato, Hajime Igarashi

  IEEE Transactions on Magnetics 0018-9464 2021 [Refereed][Not invited]
   

  This paper proposes a method based on three-dimensional discrete element and finite element methods to numerically evaluate the effect of the particle size distribution of soft composite material (SMC) on the electromagnetic property. The three SMC models which obey Gaussian, homogeneous and twin-peak distributions are compared using the proposed method. It is shown that Gaussian model has the highest permeability and lowest loss at high frequencies under the condition that the three models have the same filling rate.
• Topology Optimization using Deep Learning: Comparison of Simultaneous and Additional Learning

  Hidenori Sasaki, Yuki Hidaka, Hajime Igarashi

  IEEJ Transactions on Power and Energy 140 (12) 858 - 865 0385-4213 2020/12 [Refereed][Not invited]
  
• Cauer-Equivalent Circuit for Inductors Considering Hysteresis Magnetic Properties for SPICE Simulation

  Yuki Sato, Kenji Kawano, Dongbin Hou, Jeffrey Morroni, Hajime Igarashi

  IEEE Transactions on Power Electronics 35 (9) 9663 - 9670 0885-8993 2020/09 [Refereed][Not invited]
   

  © 1986-2012 IEEE. This article presents a new method to synthesize the Cauer-equivalent circuit for inductors that can represent the hysteresis, eddy current, anomalous core losses, dc and ac winding losses as well as inductance. Only the measurement of inductor loss under the sinusoidal excitation is required to synthesize the SPICE loss model. The proposed circuit model can be used to evaluate the loss under arbitrary voltage/current excitations. In the proposed approach, the measured loss is subdivided into the ac and hysteresis losses. Then, the Cauer-equivalent circuit for SPICE simulation is synthesized from the loss model. It is shown that the losses evaluated by the proposed model are in good agreement with the measured results under the condition of the sinusoidal and triangular cases with and without dc bias current.
• Optimization of Planar Magnet Array Using Digital Annealer

  Akito Maruo, Hajime Igarashi, Hirotaka Oshima, Satoshi Shimokawa

  IEEE Transactions on Magnetics 56 (3) 0018-9464 2020/03 [Refereed][Not invited]
   

  © 1965-2012 IEEE. This article presents a fast optimization of a 2-D magnetic array using digital annealer, a hardware system which solves quadratic unconstrained binary optimization problems with massive parallelization. The magnetic-array structure, which is used for a vibration energy harvester and a planar motor, is optimized so that the induced voltage in coils placed above the array is maximized. A novel structure of a planar magnet array without the non-magnetic region is obtained as an extension of the Halbach array.
• Transfer Learning through Deep Learning: Application to Topology Optimization of Electric Motor

  Jo Asanuma, Shuhei Doi, Hajime Igarashi

  IEEE Transactions on Magnetics 56 (3) 0018-9464 2020/03 [Refereed][Not invited]
   

  © 1965-2012 IEEE. This article proposes the use of transfer learning for the deep neural network to reduce the computing cost of the topology optimization of electric motors based on a genetic algorithm (GA). The average torque and torque ripple values are shown to be accurately inferred by the transfer learning with small learning data. The individuals on the Pareto front are only evaluated by the finite-element method, while others are fast evaluated only by convolutional neural networks (CNNs). The proposed method makes it possible to reduce the computing cost to less than 15% of the conventional topology optimization method.
• Model Order Reduction for Linear Time-Invariant System with Symmetric Positive-Definite Matrices: Synthesis of Cauer-Equivalent Circuit

  Shingo Hiruma, Hajime Igarashi

  IEEE Transactions on Magnetics 56 (3) 0018-9464 2020/03 [Refereed][Not invited]
   

  © 1965-2012 IEEE. This article introduces a new model order reduction method for a linear time-invariant system with symmetric positive-definite matrices. The proposed method allows the construction of a reduced model, represented by a Cauer-equivalent circuit, from the original system. The method is developed by extending the Cauer ladder network method for the quasi-static Maxwell's equations, which is shown to be regarded as the Lanczos algorithm with respect to a self-adjoint matrix. As a numerical example, a Cauer-equivalent circuit is generated from a simple mathematical model as well as the finite-element (FE) model of a magnetic reactor that is driven by a pulsewidth modulation voltage wave. The instantaneous power obtained from the circuit analysis is shown to be in good agreement with that obtained from the original FE model.
• Equivalent Circuit Allowing Loss Separation Synthesized from Field Computations: Application to Induction Heating

  Toshihito Shimotani, Hajime Igarashi, Eiji Hashimoto, Hiroyuki Imanari

  IEEE Transactions on Magnetics 56 (2) 0018-9464 2020/02 [Refereed][Not invited]
   

  © 1965-2012 IEEE. This article presents a method to synthesize the equivalent circuit of an induction heating (IH) machine used in the hot strip mill (HSM) process. The equivalent circuit not only allows to evaluate eddy current losses in different forms, such as iron plate and coils, but also compute the transient responses in online environments. The frequency characteristic of the IH machine is effectively computed by proper orthogonal decomposition. The equivalent circuit of the IH is synthesized through curve fitting to the computed characteristics in conjunction with Tikhonov's regularization. The equivalent circuit is shown to have good accuracy and works much faster than the finite-element method. The proposed equivalent circuit is expected to be used in online control of the HSM process.
• Fast Analysis of Rotating Machine Using Simplified Model-Order Reduction Based on POD

  Hiroki Sakamoto, Kazuya Okamoto, Hajime Igarashi

  IEEE Transactions on Magnetics 56 (2) 0018-9464 2020/02 [Refereed][Not invited]
   

  © 1965-2012 IEEE. This article proposes a simplified model-order reduction for the fast dynamic simulation of electric motors. The magnetic fields are snapshotted for different input currents at each mechanical angle to construct a data matrix. The basis vectors are then computed by the singular value decomposition applied to the data matrix. The interpolation along the mechanical angle is performed by the dynamic mode decomposition. Fast computation of the magnetic field for arbitrary input current and mechanical angle is performed through interpolation of the basis vectors in the space of input currents for the dynamic analysis of motors.
• Time-Domain Analysis of Magnetically Shielded Wire Coils Using Homogenized Finite-Element Method

  Shogo Fujita, Shingo Hiruma, Hajime Igarashi

  IEEE Transactions on Magnetics 56 (2) 0018-9464 2020/02 [Refereed][Not invited]
   

  © 1965-2012 IEEE. A magnetically shielded wire (MSW) is effective for the reduction of the eddy-current loss due to the proximity effect. When using the finite-element method (FEM), it is challenging to analyze the electric apparatus, including MSWs, because its radius is much smaller than the overall machine size. This problem can be circumvented by modeling a multiturn MS coil (MSC) as uniform material with the macroscopic complex permeability defined in the frequency domain. This article presents an extension of this homogenization method to the time domain. The inverse Laplace transform is effectively performed by expanding the complex permeability into partial fractions. It is shown that the proposed method is accurate even when the magnetic saturation of the magnetic core is in effect.
• Homogenization Method Based on Cauer Circuit via Unit Cell Approach

  Shingo Hiruma, Hajime Igarashi

  IEEE Transactions on Magnetics 56 (2) 0018-9464 2020/02 [Refereed][Not invited]
   

  © 1965-2012 IEEE. This article proposes a novel homogenization method based on the unit cell approach which provides the continued fraction and, equivalently, the Cauer circuit representation of the complex permeability of fine structure materials. The proposed method makes it possible to perform the homogenization analysis in time domain. It is shown that the proposed method provides a more accurate resistance factor in comparison to the Dowell method and other classical methods.
• Multi-objective topology optimization of magnetic couplers for wireless power transfer

  Yunyi Gong, Yoshitsugu Otomo, Hajime Igarashi

  INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS 64 (1-4) 325 - 333 1383-5416 2020 

  In this paper, the multi-objective topology optimizations of wireless power transfer (WPT) devices with two different coil geometries are proposed for obtaining the designs with good balance between transfer efficiency and safety. For this purpose, the proposed method adopts the normalized Gaussian network (NGnet) and Non-dominated Sorting Genetic Algorithm II (NSGA-II). In addition, the optimization under the different constraint on ferrite volume is carried out to verify its influence on optimization results. It has been shown that the proposed method successfully provides the Pareto solution to the design problem of the WPT device.
• Three-dimensional optimization of meander inductor

  Takahiro Sasaki, Hajime Igarashi

  INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS 64 (1-4) 343 - 350 1383-5416 2020 [Refereed]
   

  This paper presents a three-dimensional optimization method of a meander inductor for high-frequency circuits. The proposed method determines the structure of the meander line using the micro-genetic algorithm in which the eddy current loss and inductance are evaluated by finite element method. It is shown that the total loss composed of the eddy current loss in the magnetic core and Joule loss in the meander line is successfully minimized keeping the inductance to the specified value by this optimization.
• Simulation Methods for Power Inductors : Homogenization and Model Order Reduction

  五十嵐 一, 比留間 真悟, 佐藤 駿輔

  まぐね = Magnetics Japan 日本応用磁気学会 15 (3) 173 - 178 1880-7208 2020 [Refereed][Invited]
  
• 3-D topology optimization of claw-pole alternator using Gaussian-basis function with global and local searches

  Yoshitsugu Otomo, Hajime Igarashi, Yuki Hidaka, Taiga Komatsu, Masaki Yamada

  IEEE Transactions on Magnetics 56 (1) 0018-9464 2020/01 [Refereed][Not invited]
   

  © 1965-2012 IEEE. This article proposes a two-step topology optimization method based on the normalized Gaussian functions. The proposed method is shown to be effective for design of a claw-pole alternator. In this method, the global search using the micro-genetic algorithm (μ GA) is followed by the local search using the sensitivity analysis based on the adjoint variable method. The 3-D structure of the rotor is optimized using the proposed method under low- and high-speed conditions.
• Time-domain analysis of homogenized finite-element method for eddy current analysis with reduced unknown variables

  Shingo Hiruma, Hajime Igarashi

  IEEE Transactions on Magnetics 56 (1) 0018-9464 2020/01 [Refereed][Not invited]
   

  © 1965-2012 IEEE. This article presents a new method for time-domain analysis based on the homogenized finite-element method (FEM). The permeability in the homogenized domain is expressed by the Cauer-equivalent circuit. The auxiliary unknowns relevant to the Cauer circuit are then eliminated using the finite-difference method. The homogenized finite-element (FE) equation without the auxiliary unknowns can be effectively solved.
• Synthesis of Equivalent Circuit from Homogenized FE Equation using Model Order Reduction

  Shingo Hiruma, Hajime Igarashi

  IEEJ Transactions on Power and Energy 140 (2) 134 - 139 0385-4213 2020 [Refereed][Not invited]
   

  © 2020 The Institute of Electrical Engineers of Japan. This paper introduces a novel method for synthesis of the equivalent circuit of an electromagnetic system described by a homogenized FE equation via model order reduction. The homogenization method replaces fine-structured material such as multi-turn coils, soft magnetic composite and laminated iron sheets with uniform material with complex permeability. The present method reduces the FE equation including the complex permeability to a circuit equation for small variables which can be solved with small computational cost. The present method is effective for time-domain analysis and makes it possible to consider magnetic saturations.
• Time-Domain Finite Element Analysis of Multi-turn Coil with Elliptic Cross Section using based on Homogenization Method

  Fujita Shogo, Igarashi Hajime

  IEEJ Transactions on Power and Energy 一般社団法人 電気学会 140 (5) 402 - 408 0385-4213 2020 [Refereed][Not invited]
   

  In this paper, a homogenized finite element method for transient analysis of electric apparatus including a multi-turn coil with elliptic cross-section. The tensor-type complex permeability of the multi-turn coil is expanded into partial fractions, which can then be transformed into time-domain. The convolution integral is effectively evaluated using the RC method which does not need large memory storage. It is shown that the power computed by the proposed method is in good agreement with that computed by the conventional finite element method without homogenization.

• Implementation of Simplified Model Order Reduction Based on POD for Dynamic Simulation of Electric Motors

  Kazuya Okamoto, Hiroki Sakamoto, Hajime Igarashi

  COMPUMAG 2019 - 22nd International Conference on the Computation of Electromagnetic Fields 2019/07/01 

  This paper proposes a fast method for dynamic simulation of electric motors using the simplified model order reduction based on the proper orthogonal decomposition (POD). In the proposed method, the reduced variables multiplied to the basis vectors of magnetic field are directly interpolated using finite elements on the space spanned by the input currents. The field quantities such as torque and iron loss are computed at high computational efficiency without solving equations in the dynamic simulation. It is shown that the proposed method works more than fifty times faster than the conventional finite element method at high accuracy.
• Multi-Objective Topology Optimization of Rotating Machines Using Deep Learning

  Doi Shuhei, Sasaki Hidenori, Igarashi Hajime

  IEEE TRANSACTIONS ON MAGNETICS IEEE (Institute of Electrical and Electronics Engineers) 55 (6) 7202605 - 7202605 0018-9464 2019/06 [Refereed][Not invited]
  
• Reduction of Eddy Current Loss in Rectangular Coils Using Magnetic Shield: Analysis With Homogenization Method

  Fujita Shogo, Igarashi Hajime

  IEEE TRANSACTIONS ON MAGNETICS 55 (6) 0018-9464 2019/06 [Refereed][Not invited]
  
• Identification of Magnetization Characteristics of Material From Measured Inductance Data

  Maruo Akito, Igarashi Hajime, Sato Yuki, Kawano Kenji

  IEEE TRANSACTIONS ON MAGNETICS 55 (6) 0018-9464 2019/06 [Refereed][Not invited]
  
• Analysis of Magnetic Properties of Soft Magnetic Composite Using Discrete Element Method

  Maruo Akito, Igarashi Hajime

  IEEE TRANSACTIONS ON MAGNETICS 55 (6) 0018-9464 2019/06 [Refereed][Not invited]
  
• A 3-D Topology Optimization of Magnetic Cores for Wireless Power Transfer Device

  Otomo Yoshitsugu, Igarashi Hajime

  IEEE TRANSACTIONS ON MAGNETICS 55 (6) 0018-9464 2019/06 [Refereed][Not invited]
   

  This paper presents the topology optimization of the magnetic core for a wireless power transfer (WPT) device. In this optimization, the coil and magnetic-core shapes for WPT are represented by the Gaussian basis functions. They are sequentially optimized using the genetic algorithm and 3-D finite-element analysis so that the coupling coefficient of the WPT device is maximized. Moreover, a robust optimization method is proposed to keep the interlinkage flux as large as possible against misalignment in the coils. It is shown by the computational and experimental results that the optimized device outperforms the conventional devices.
• Topology Optimization Accelerated by Deep Learning

  Sasaki Hidenori, Igarashi Hajime

  IEEE TRANSACTIONS ON MAGNETICS IEEE (Institute of Electrical and Electronics Engineers) 55 (6) 7401305 - 7401305 0018-9464 2019/06 [Refereed][Not invited]
  
• Homogenization of multi-turn coil with elliptic cross-section using complex permeability

  Fujita Shogo, Igarashi Hajime

  COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING 38 (3) 999 - 1008 0332-1649 2019/05/07 [Refereed][Not invited]
  
• Topology Optimization of Metamaterial Using Gaussian-Basis Functions

  Ye Fangzhou, Hajime Igarashi

  JOURNAL OF ADVANCED SIMULATION IN SCIENCE AND ENGINEERING 6 (1) 149 - 156 2188-5303 2019 [Refereed][Not invited]
   

  This paper presents topology optimization of electromagnetic metamaterial using the on/off method based on the Normalized Gaussian network (NGnet). In this work, the conductor shape printed on a dielectric slab of fixed dimensions is optimized to have a negative macroscopic permeability at a prescribed frequency band for realization of metamaterial. It is shown that the proposed method successfully provides the metamaterial that works at any desired operating frequency.
• Topology optimization of IPM motor with aid of deep learning

  Sasaki Hidenori, Igarashi Hajime

  INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS 59 (1) 87 - 96 1383-5416 2019 [Refereed][Not invited]
   

  This paper presents a new topology optimization of interior permanent magnet (IPM) motors using the genetic algorithm with aid of the deep leaning. The data composed of the rotor shape of an IPM motor and its performance, obtained by a prior topology optimization process, is input to a convolutional neural network (CNN). After the learning process, CNN is shown to provide fairly accurate estimate of the motor performance. During the posterior topology optimization, the finite element analysis (FEA) is carried out only for the limited number of individuals; probability that FEA is performed increases with the motor performance evaluated by CNN. It is shown that the computing time is reduced to about 1/10 without deterioration of the optimization performance with aid of the deep learning.
• Magnetic circuit modeling of chaotic vibration energy harvester

  Maruo Akito, Igarashi Hajime

  INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS 59 (2) 567 - 575 1383-5416 2019 [Refereed][Not invited]
  
• Fast computation of copper and iron losses using model order reduction

  Hiruma Shingo, Igarashi Hajime

  INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS 60 S79 - S86 1383-5416 2019 [Refereed][Not invited]
  
• 3-D topology optimization of magnetic cores for wireless power transfer with double-sided winding coils

  Otomo Yoshitsugu, Igarashi Hajime

  INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS 60 S115 - S123 1383-5416 2019 [Refereed][Not invited]
   

  This paper presents three-dimensional topology optimization of magnetic cores for wireless power transfer with double-sided winding coils. In this optimization, the magnetic core shape is represented by the linear combination of the normalized Gaussian functions. The core shape is optimized so that the coupling coefficient between the transmitting and receiving coils is maximized. Moreover, robustness against misalignment between the coils is taken into account in the optimization. It is found that the optimized core shape effectively increases the net magnetic flux interlinked with the receiving coil, and outperforms the conventional core shapes.
• Finite element analysis of multi-turn magnetoplated coils using homogenization method

  Shogo Fujita, Hajime Igarashi

  Electrical Engineering in Japan (English translation of Denki Gakkai Ronbunshi) 205 23 - 31 0424-7760 2018/12 [Refereed][Not invited]
   

  © 2018 Wiley Periodicals, Inc. Magnetoplated wires (MPW) are effective to reduce eddy current losses in power devices such as converters and contactless power transfer systems. In the conventional finite element analysis (FEA) of MPW, elements must be sufficiently smaller than the skin depth. This results in large number of unknowns. This article proposes a homogenization method using complex permeability for FEA of magnetoplated coils so as to circumvent this problem. The coil impedances obtained by the proposed method with coarse elements are shown to agree well with those computed in the conventional FEA with fine elements.
• A passive SPICE model for rectennas

  Polyanna Mara Pereira, Felipe Campelo, Takuya Mori, Hajime Igarashi, Ricardo Adriano

  COMPEL - The International Journal for Computation and Mathematics in Electrical and Electronic Engineering 37 1905 - 1917 0332-1649 2018/11 [Refereed][Not invited]
   

  © 2018, Emerald Publishing Limited. Purpose: This paper aims to present a SPICE model to represent antennas in receiving mode. The model can be used to evaluate the performance of the antenna when it is coupled to several different nonlinear electric circuits. The proposed methodology is particularly suitable for rectenna applications, as it allows the analysis of different configurations for a rectenna more efficiently than using full-wave analysis simulators coupled directly to each rectifier circuit. Design/methodology/approach: The model presented uses reciprocity theory to calculate the ideal voltage source of the Thevenin-equivalent circuit for an antenna. Vector fitting is then used to approximate the model to rational functions that can be converted to Resistor, Inductor and Capacitor circuits. Additional components are added to the circuit to prevent numerical instability. Findings: Two rectennas are used to illustrate the performance of the proposed model, one based on a 2.45-GHz rectangular patch antenna and another based on a planar spiral antenna. The second antenna has impedance with positive and negative real parts along the frequency range, which could lead to numerical instabilities. The proposed method is shown to be stable while working with these negative resistance values, which may appear during circuit parameterization. Research limitations/implications: The equivalent SPICE circuit model for the antenna makes it easy to simulate nonlinear circuits connected to the antenna and perform transient analyses. The computational cost of antenna analysis is reduced, being more computationally efficient than methods that involve full-wave simulation. This characteristic makes it an interesting approach for working with rectennas, or any application where the time constant of the circuit is much longer than the period of the incident wave. Originality/value: For most antenna applications, the numerical stability of the circuit can be achieved using passive enforcement. However, depending on the phase response of the antenna, the impedance that represents its far-field characteristic may present a negative real part, in which case, passive enforcement will fail. In this paper, the problem of numerical instability is solved by introducing an offset resistance and a current-controlled voltage source to the model.
• Development of small dielectric lens for slot antenna using topology optimization with normalized Gaussian network

  Keiichi Itoh, Haruka Nakajima, Hideaki Matsuda, Masaki Tanaka, Hajime Igarashi

  IEICE Transactions on Electronics E101C 784 - 790 0916-8524 2018/10 [Refereed][Not invited]
   

  Copyright © 2018 The Institute of Electronics, Information and Communication Engineers. This paper reports a novel 3D topology optimization method based on the finite difference time domain (FDTD) method for a dielectric lens antenna. To obtain an optimal lens with smooth boundary, we apply normalized Gaussian networks (NGnet) to 3D topology optimization. Using the proposed method, the dielectric lens with desired radiation characteristics can be designed. As an example of the optimization using the proposed method, the width of the main beam is minimized assuming spatial symmetry. In the optimization, the lens is assumed to be loaded on the aperture of a waveguide slot antenna and is smaller compared with the wavelength. It is shown that the optimized lens has narrower beamwidth of the main beam than that of the conventional lens.
• Fast 3-D Optimization of Magnetic Coressc forsc Losssc and Volume Reduction

  Satoshi Shimokawa, Hirotaka Oshima, Koichi Shimizu, Yuji Uehara, Jun Fujisaki, Atsushi Furuya, Hajime Igarashi

  IEEE Transactions on Magnetics 0018-9464 2018/06 [Refereed][Not invited]
   

  IEEE This paper presents an effective design method for inductors which is based on the multi-objective optimization accelerated by the artificial neural network (ANN). In the learning phase prior to the optimization phase, ANN is trained for 1000 input-output data sets obtained from the finite-element analysis for randomly generated dimensional parameters. The magnetic hysteresis of the ferrite core is modeled by the play model to evaluate the hysteresis losses. The multi-objective optimization problems are solved by the genetic algorithm in which the magnetic loss is effectively computed by the trained ANN to reduce the core volume as well as magnetic loss. The Pareto solutions for an EI-shaped ferrite core are obtained for different inductances. It is shown that the proposed method works much faster than the conventional optimization, and the magnetic loss and the inductance of the optimized inductor agree well with the experimental results.
• Eddy Current Analysis of Litz Wire Using Homogenization-Based FEM in Conjunction with Integral Equation

  Shingo Hiruma, Yoshitsugu Otomo, Hajime Igarashi

  IEEE Transactions on Magnetics 54 (3) 0018-9464 2018/03/01 [Refereed][Not invited]
   

  A new method is introduced to evaluate the macroscopic permeability of a litz wire which is composed of stranded conductors. In this method, an integral equation is solved for the complex magnetization in the litz wire generated due to the proximity effect. The macroscopic permeability computed from the magnetization is used in the homogenization-based finite-element analysis of eddy currents in a litz-wire coil. It is shown that the wire twist has a little effect on the complex permeability.
• Synthesis of Equivalent Circuit of Wireless Power Transfer Device Using Homogenization-Based FEM

  Yoshitsugu Otomo, Yuki Sato, Shogo Fujita, Hajime Igarashi

  IEEE Transactions on Magnetics 54 (3) 0018-9464 2018/03/01 [Refereed][Not invited]
   

  In this paper, the multi-turn coil used in a wireless power transfer (WPT) device is modeled as a uniform material using the homogenization method to consider the proximity effect. By fitting the coil impedance to the numerical results, the Cauer equivalent circuit of the multi-turn coil is synthesized for the design and optimization of the power circuits in the WPT device. It is shown that the results obtained from the equivalent circuit and measurement are in good agreement. Moreover, the impedance of a flat WPT coil composed of a Litz wire is shown to be accurately evaluated by the proposed method when the contribution of capacitance is negligible.
• Topology optimization using basis functions for improvement of rotating machine performances

  Hidenori Sasaki, Hajime Igarashi

  IEEE Transactions on Magnetics 54 (3) 0018-9464 2018/03/01 [Refereed][Not invited]
   

  This paper presents a new topology optimization method based on basis functions for design of rotating machines. In this method, the core shape of a given rotating machine is represented by the linear combination of the basis functions. The shape is then freely deformed by changing the weighting coefficients to the basis functions to find the optimal shape. The proposed method is compared with the conventional shape optimization based on polygon morphing. The former is shown to outperform the latter in both interior permanent magnet and synchronous motor models.
• Finite-element analysis of magnetically shielded wire coils using homogenization method

  Shogo Fujita, Hajime Igarashi

  IEEE Transactions on Magnetics 54 (3) 0018-9464 2018/03/01 [Refereed][Not invited]
   

  A magnetically shielded wire (MSW), which has magnetic-conductive thin layers on the surface of a wire conductor, is expected to reduce the eddy current losses due to the proximity effect. The conventional finite-element method (FEM) needs unacceptably long computational time to analyze eddy currents in multi-turn MSWs. This paper proposes a homogenization method, which models MSW as a uniform material with complex permeability. The coil impedance evaluated by the homogenization-based FEM with coarse elements is shown to agree well with that obtained by the conventional FEM with much finer elements. Moreover, the optimal shield thickness is determined by the proposed method.
• Three-Dimensional Shape Optimization of Claw Pole-Motors

  Hidaka Yuki, Igarashi Hajime

  JOURNAL OF ADVANCED SIMULATION IN SCIENCE AND ENGINEERING 4 (1) 64 - 77 2188-5303 2018 [Refereed][Not invited]
  
• Properties of chaotic vibration energy harvester: comparison of numerical results with experiments

  Takeshi Sugisawa, Hajime Igarashi

  INTERNATIONAL JOURNAL OF NUMERICAL MODELLING-ELECTRONIC NETWORKS DEVICES AND FIELDS 30 (5) 0894-3370 2017/09 [Refereed][Not invited]
   

  Energy-harvesting devices have been developed for the use of voltage sources in low-powered wireless sensors. Vibration energy harvesters generate electric power from ambient vibration of constructions such as bridges, tunnel walls, and power pylons. Vibration energy harvesters are required to have high power generation efficiency over a wide vibration frequency. This paper presents a vibration energy harvester in which closed magnetic circuits are formed aiming at high efficiency and double-well potential is formed to have chaotic vibration to realize wide frequency-range power generation. In particular, the conditions for emergence of chaotic vibration are clarified based on numerical analysis and experiments.
• Fast Computation Method of Magnetic Field Homogeneity for NMR/MRI REBCO Pancake Coils

  Ryosuke Miyao, Hajime Igarashi, SeokBeom Kim, So Noguchi

  IEEE Transactions on Applied Superconductivity 27 (4) 1 - 4 1051-8223 2017/06 [Refereed]
  
• A New Adaptive Mesh Refinement Method in FEA Based on Magnetic Field Conservation at Elements Interfaces and Non-Conforming Mesh Refinement Technique

  So Noguchi, Takuto Naoe, Hajime Igarashi, Shinya Matsutomo, Vlatko Cingoski, Akira Ahagon, Akihisa Kameari

  IEEE TRANSACTIONS ON MAGNETICS 53 (6) 0018-9464 2017/06 [Refereed][Not invited]
   

  Mesh quality strongly affects the solution accuracy in electromagnetic finite-element analysis. Hence, the realization of adequate mesh generation becomes a very important task. Several adaptive meshing methods for automatic adjustments of the mesh density in accordance with the shape and complexity of the analyzed problem have been proposed. However, the most of them are not enough robust, some are quite laborious and could not be universally used for adaptive meshing of complex analysis models. In this paper, a new adaptive mesh refinement method based on magnetic field conservation at the border between finite elements is proposed. The proposed error estimation method provides easy mesh refinements, and generates smaller element within regions with large curvature of the magnetic flux lines. The proposed adaptive mesh refinement method based on non-conforming edge finite elements, which could avoid generation of flat or ill-shaped elements, was applied to a simple magnetostatic permanent magnet model. To confirm the validity and accuracy, the obtained results were compared with those obtained by means of the Zienkiewicz-Zhu (ZZ) error estimator. The results show that the computational error using the proposed method was reduced down to 1% compared with that of the ZZ method, which yields error of 8.6%, for the same model.
• Time-Domain Analysis of Soft Magnetic Composite Using Equivalent Circuit Obtained via Homogenization

  Yuki Sato, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 53 (6) 0018-9464 2017/06 [Refereed][Not invited]
   

  This paper presents a homogenized analysis of soft magnetic composite (SMC), which is composed of small iron particles embedded in insulating medium. The SMC core is modeled by uniform material with the macroscopic complex permeability which is analytically represented in frequency domain. The Cauer-equivalent circuit is synthesized from the macroscopic permeability for time-domain analysis of SMC. The proposed method is shown valid even when SMC is magnetically saturated.
• Homogenization Method Based on Model Order Reduction for FE Analysis of Multi-Turn Coils

  Yuki Sato, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 53 (6) 0018-9464 2017/06 [Refereed][Not invited]
   

  This paper presents a homogenization method based on the model order reduction (MOR) for finite element (FE) analysis of multi-turn coils. The multi-turn coils are replaced by a homogenous material with the complex permeability that is expressed by a rational polynomial of frequency. After the MOR process, the complex permeability can readily be computed at any frequency. It is shown that the present method can drastically reduce the computational time without loss of accuracy.
• Topology Optimization of Synchronous Reluctance Motors Considering Localized Magnetic Degradation Caused by Punching

  Yuki Hidaka, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 53 (6) 0018-9464 2017/06 [Refereed][Not invited]
   

  The magnetic characteristic of magnetic steel sheets used for rotating machines can be degraded by punching, cutting, or other manufacturing process. This degradation damages the performances of motors. This paper presents topology optimization of rotating machines considering the localized magnetic degradation caused by punching process. It is shown that the optimized synchronous reluctance motors obtained by this method satisfy the torque constraint under the existence of the magnetic degradation.
• Synthesis of Cauer-Equivalent Circuit Based on Model Order Reduction Considering Nonlinear Magnetic Property

  Yuki Sato, Toshihito Shimotani, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 53 (6) 0018-9464 2017/06 [Refereed][Not invited]
   

  The Cauer-equivalent circuit of electric apparatus is synthesized by applying the model order reduction to the finite-element equations. In this method, the admittance function of a given electric apparatus is expressed by a rational polynomial from which the Cauer-equivalent circuit is directly synthesized. Magnetic saturation in the magnetic core is considered by introducing nonlinearity in the primal inductance of the circuit. The synthesized circuit is shown to express the input-output properties of inductors and induction heating devices in good accuracy.
• Fast 3-D Analysis of Eddy Current in Litz Wire Using Integral Equation

  Shingo Hiruma, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 53 (6) 0018-9464 2017/06 [Refereed][Not invited]
   

  Eddy current loss in a litz wire which has 3-D structure is analyzed using the integral equation method considering the proximity effect. In the present method, each wire is modeled as a polygonal line. 1-D integral equation is solved for the dipole magnetization generated by the anti-parallel eddy currents in the wire. The discretized integral equation can effectively be solved using an iterative method solver to compute the eddy current distribution in the wire due to the proximity effect.
• Technical Development Report

  五十嵐 一, 佐々木 秀徳

  IEEJ Transactions on Industry Applications 一般社団法人 電気学会 137 (10) NL10_5 - NL10_5 2017
• トポロジー最適化によるアンテナ指向性の狭角化および広角化

  伊藤 桂一, 五十嵐 一

  電気関係学会東北支部連合大会講演論文集 電気関係学会東北支部連合大会実行委員会 2017 178 - 178 2017
• Topology Optimization for a SynRM Rotor Using Normalized Gaussian Basis Function

  Sasaki Hidenori, Igarashi Hajime

  The Proceedings of The Computational Mechanics Conference 一般社団法人 日本機械学会 2017 (0) 145 - 145 2017 

  本報告では既存の形状の性能改善のための正規化ガウス基底関数を用いたトポロジー形状最適化を提案する．本手法をシンクロナスリラクタンスモータに用いることで本手法の有用性を検討する．また，得られた形状をスムージングした際の特性への影響について考察を行う．
• Time-periodic eddy current analysis using model order reduction and time-periodic explicit error correction method

  Yuki Sato, Hajime Igarashi

  IEEJ Transactions on Power and Energy 137 (3) 202 - 207 1348-8147 2017 [Refereed][Not invited]
   

  This paper introduces a fast time-periodic eddy current analysis using model order reduction (MOR) and timeperiodic explicit error correction (TP-EEC) method. In this method, the size of the original system is reduced by MOR and simultaneously, the convergence to steady states is accelerated by TP-EEC. It is shown that the speedup ratio of the present method compared with the conventional FEM is more than 30 for a nonlinear test problem.
• Topology optimization of IPM motors using fourier series

  Hidenori Sasaki, Hajime Igarashi

  IEEJ Transactions on Power and Energy 電気学会 137 (3) 245 - 253 1348-8147 2017 [Refereed][Not invited]
   

  This paper proposes a topology optimization method for rotating machines, in which the rotor shape is represented in terms of the Fourier series. The rotor shape of an IPM motor is optimized to maximize the average torque and minimize radial torque variations using the present method. The proposed method is shown to provide the optimized rotors whose performances are comparable with those obtained by the NGnet-based method. The topology optimization performed by both methods can give useful information on the motor design.
• Finite element analysis of multi-turn magnetoplated coils using homogenization method

  Shogo Fujita, Hajime Igarashi

  IEEJ Transactions on Power and Energy 電気学会 137 (3) 223 - 229 1348-8147 2017 [Refereed][Not invited]
   

  Magnetoplated wires (MPW) are effective to reduce eddy current losses in power devices such as converters and contactless power transfer systems. In the convenient finite element (FE) analysis of MPW, elements must be sufficiently smaller than the skin depth. This results in large number of unknowns. This paper proposes a homogenization method using complex permeability for FE analysis of MP-coils so as to circumvent this problem. The coil impedances obtained by the proposed method with coarse elements are shown to agree well with those computed in the conventional FE analysis with fine elements.
• Topology optimization of rotation machine using on-off method with variable design region

  Yuki Hidaka, Hajime Igarashi

  IEEJ Transactions on Power and Energy 電気学会 137 (3) 208 - 215 1348-8147 2017 [Refereed][Not invited]
   

  This paper presents topology optimization of rotating machines using the On-Off method with variable design region. The flux barrier shape is optimized by the present method in which the thin design regions covering the boundary of the flux barriers are adaptively modified during the optimization process. Because the design region is strongly restricted, the optimized flux barrier boundaries are expected to be rather smooth even if the smoothing procedure is not employed. Moreover the present method is based on the evolutionary algorithm which has powerful searching abilities. In order to validate its effectiveness, the flux barrier shapes of the interior permanent magnetic motors and synchronous reluctance motors are optimized by the present method. The performance of the present method is shown to be superior over that of the Rosen-brock method.
• Semi-Analytical Approach for Finite-Element Analysis of Multi-Turn Coil Considering Skin and Proximity Effects

  Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 53 (1) 0018-9464 2017/01 [Refereed][Not invited]
   

  Native application of finite-element method (FEM) to the analysis of skin and proximity effects in multi-turn coils results in large equation systems, whose solution needs long computational time. This paper proposes a semi-analytical approach to overcome this problem. For the analysis of the proximity effect, the complex permeability of a round conducting wire immersed in uniform time-harmonic magnetic fields is represented in a closed form. Then, the homogenized complex permeability over the cross section of the multi-turn coil is analytically evaluated using the Ollendorff formula. The magnetoquasistatic problem is thus replaced by the magnetostatic one, in which the multi-turn coil is treated as a uniform material with the homogenized complex permeability. The skin effect is taken into consideration by introducing the corresponding impedance in the circuit equation. The proposed method is shown to give the impedance of multi-turn coils, which is in good agreement with that obtained by the conventional FEM as well as experiments.
• Adaptive Subdomain Model Order Reduction With Discrete Empirical Interpolation Method for Nonlinear Magneto-Quasi-Static Problems

  Yuki Sato, Markus Clemens, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 52 (3) 0018-9464 2016/03 [Refereed][Not invited]
   

  This paper presents a novel adaptive subdomain model order reduction (MOR) based on proper orthogonal decomposition (POD) and discrete empirical interpolation (DEI) methods for nonlinear magneto-quasi-static (MQS) problems. In this method, a nonlinear region is decomposed into two regions, where one of the regions includes all those finite elements that have a particularly strong saturation and the other region does not. MOR based on POD and DEI methods is applied only to the latter region. Both the regions are determined automatically at each time step. It is shown that this method can effectively reduce the computational time to solve the nonlinear MQS problems without losing the quality of accuracy.
• Effect of Magnetic Contact on Macroscopic Permeability of Soft Magnetic Composite

  Yasuhisa Ito, Hajime Igarashi, Michiaki Suzuki, Yoshiki Iwasaki, Kenji Kawano

  IEEE TRANSACTIONS ON MAGNETICS 52 (3) 0018-9464 2016/03 [Refereed][Not invited]
   

  It is revealed that the contact of magnetic particles in soft magnetic composite (SMC) significantly increases the macroscopic permeability. It is shown that Ollendorff's formula, which assumes homogenous magnetic particles and insulation layers, underestimates the macroscopic permeability of SMC. It is suggested that the excess in the permeability is due to the local contacts among the magnetic particles. The effect of the magnetic contact is evaluated using a magnetic circuit model.
• Equivalent-Circuit Generation From Finite-Element Solution Using Proper Orthogonal Decomposition

  Toshihito Shimotani, Yuki Sato, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 52 (3) 0018-9464 2016/03 [Refereed][Not invited]
   

  This paper presents the generation of equivalent circuits from a finite-element (FE) model of electromagnetic devices using proper orthogonal decomposition (POD). This method effectively computes the frequency response of the reduced FE model constructed by the POD-based model order reduction. Then, the circuit parameters are determined so as to minimize the error between the frequency responses of the reduced FE model and equivalent circuit. The frequency characteristics of an inductor and the induction heating machine evaluated by the equivalent circuit are shown to be in good agreement with those computed from the original FE model.
• Fast Finite-Element Analysis of Motors Using Block Model Order Reduction

  Toshihito Shimotani, Yuki Sato, Takahiro Sato, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 52 (3) 0018-9464 2016/03 [Refereed][Not invited]
   

  This paper proposes a model order reduction (MOR) based on the proper orthogonal decomposition (POD) to perform a fast analysis of motors. When a POD-based MOR is applied to the motor analysis, the number of basis vectors has to be increased to express the changes in the magnetic fields due to a rotational movement. Its computational efficiency is, thus, greatly deteriorated. To overcome this difficulty, the block-MOR is first applied to a motor analysis. In this method, a parameter space is subdivided into several blocks, which correspond to angular ranges in the motor analysis, in each of which the basis vectors are constructed from snapshotted fields. The computational time of the block-MOR is shown to be shorter than that of the conventional MOR, while the accuracy of both the methods is almost identical.
• Generation of Equivalent Circuit From Finite-Element Model Using Model Order Reduction

  Yuki Sato, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 52 (3) 0018-9464 2016/03 [Refereed][Not invited]
   

  This paper proposes an equivalent-circuit generation from the finite-element (FE) model of electromagnetic devices using a model order reduction (MOR). In this method, an equivalent circuit is directly generated from the reduced transfer function obtained using MOR based on Pade approximation via the Lanczos process. It is shown that the generated circuit yields sufficiently accurate results in both frequency and time domains. Moreover, the computational time of the present method is much shorter than that of the circuit generation based on frequency sweep using the conventional FE analysis.
• Fast Three-Dimensional Analysis of Eddy Currents in Litz Wire Using Integral Equation

  Shingo Hiruma, Hajime Igarashi

  2016 IEEE CONFERENCE ON ELECTROMAGNETIC FIELD COMPUTATION (CEFC) 2016 [Refereed][Not invited]
   

  Eddy current loss in a Litz wire which has three-dimensional structure is analyzed using integral equation method considering proximity effect. In the present method, one-dimensional integral equation is formulated for the perpendicular component of the complex magnetization vector generated by eddy currents in the wire. It can effectively be solved by iterative methods to compute the eddy currents due to proximity effect.
• Homogenization Method Based on Model Order Reduction for FE Analysis of Multi-turn Coils

  Yuki Sato, Hajime Igarashi

  2016 IEEE CONFERENCE ON ELECTROMAGNETIC FIELD COMPUTATION (CEFC) 2016 [Refereed][Not invited]
   

  This paper presents a homogenization method based on the model order reduction for FE analysis of multi-turn coils. In this method, using the Pade approximation via the Lanczos processes method, the macroscopic complex permeability of a multi-turn coil is expressed as a rational polynomial which is an explicit function of frequency. The macroscopic permeability which is used in FE analysis is, therefore, readily obtained for any frequency.
• Topology Optimization of Rotating Machine Rotors Considering Localized Magnetic Degradation Caused in Manufacturing Process

  Yuki Hidaka, Hajime Igarashi

  2016 IEEE CONFERENCE ON ELECTROMAGNETIC FIELD COMPUTATION (CEFC) 2016 [Refereed][Not invited]
   

  This paper presents topology optimization of rotating machine rotors considering localized magnetic degradation in rotor and stator cores caused by the manufacturing process. On the basis of experimental observation, magnetic reluctivity is assumed to exponentially decay as approaching to the processed surfaces. The present topology optimization seeks for optimal rotor shapes which are robust against the material degradation.
• Synthesis of Cauer-Equivalent Circuit Based on Model Order Reduction Considering Nonlinear Magnetic Property

  Yuki Sato, Toshihito Shimotani, Hajime Igarashi

  2016 IEEE CONFERENCE ON ELECTROMAGNETIC FIELD COMPUTATION (CEFC) 2016 [Refereed][Not invited]
   

  The Cauer-equivalent circuit of electric apparatuses is synthesized by applying the model order reduction (MOR) to their FE equations. The equivalent circuit is synthesized directly from the rational polynomial expression of the admittance function of an electric apparatus. Nonlinearity in the magnetic core of the electric apparatus can be modeled by the synthesized equivalent circuit, which is shown to accurately express the property of an inductor used in a DC-DC converter.
• Regularized Topology Optimization of IPM Motors and Post-Processing for Interpretation of Optimal Solutions

  Hidenori Sasaki, Shintaro Furui, Hajime Igarashi, Hiroki Sakamoto, Takashi Abe, Kazuya Ogura

  2016 IEEE CONFERENCE ON ELECTROMAGNETIC FIELD COMPUTATION (CEFC) 2016 [Refereed][Not invited]
   

  A topology optimization method to maximize efficiency of IPM motors is proposed. In this method, the rotor topology is represented using on/off method based on the normalized Gaussian network. To obtain rotor shapes which are easily manufactured, a regularization term is introduced in the objective function. Moreover, a post-processing method which helps users interpret the optimization results is introduced.
• Time-domain Analysis of Soft Magnetic Composite Using Equivalent Circuit Obtained via Homogenization

  Yuki Sato, Hajime Igarashi

  2016 IEEE CONFERENCE ON ELECTROMAGNETIC FIELD COMPUTATION (CEFC) 2016 [Refereed][Not invited]
   

  This paper presents a homogenized analysis of soft magnetic composite (SMC) which is composed of small metallic magnetic particles embedded in insulating medium. The macroscopic complex permeability of SMC is obtained in frequency domain from complex permeability of the particles expressed in closed form and Ollendorff formula. On the basis of this formulation, the Cauer-equivalent circuit is synthesized for time-domain analysis of SMC.
• Three-Dimensional Shape Optimization of Claw-Pole Motors

  Yuki Hidaka, Hajime Igarashi

  2016 IEEE CONFERENCE ON ELECTROMAGNETIC FIELD COMPUTATION (CEFC) 2016 [Refereed][Not invited]
   

  This paper presents three-dimensional shape optimization of claw-pole motors. The claw-pole shape is determined from the binary state of hexahedral cells. The cell states are optimized to maximize induced voltage and minimize the field current using micro-genetic algorithm. The optimization is successfully carried out without time-consuming mesh generation.
• Equivalent circuit of antennas generated by model order reduction

  Yuki Sato, Takuya Mori, Toshihito Shimotani, Hajime Igarashi

  INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS 52 (1-2) 649 - 657 1383-5416 2016 [Refereed][Not invited]
   

  It is known that the proper orthogonal decomposition (POD), which is one of the effective approaches for model order reduction (MOR), can effectively reduce computational time for finite element method (FEM). This paper proposes a new method for generation of equivalent circuits based on POD-based FEM. In this method, the circuit parameters are determined by genetic algorithm so that the input impedance of the equivalent circuit is coincident with that computed by POD-based finite element method (FEM). For test of the proposed method, POD-based FEM is applied to analysis of a dipole antenna which is loaded with the Cockcroft Walton circuit. It is shown that this method can reduce the computational time to generate the equivalent circuit without deterioration of accuracy.
• Performance improvement of planar array antenna by small spherical dielectric lenses

  Keiichi Itoh, Kento Watanabe, Katsumasa Miyata, Hajime Igarashi

  INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS 52 (1-2) 623 - 630 1383-5416 2016 [Refereed][Not invited]
   

  This paper reports the performance improvement of the planar waveguide slot array antenna by loading the small spherical dielectric lenses. The proposed lens is sphere and small, and can be loaded on each slot independently. To design the antenna with the proposed lenses, other design parameters are fixed, and the optimal slot length is searched by using the finite difference time domain (FDTD) method. From both the calculated and the measured far-field radiation patterns, the optimized antenna with the proposed lenses shows good performance as the resonant uniformly distribution array. By comparing with the conventional antenna, it is found that the gain increase by loading small lens is estimated by 1.07 dB.
• Shape optimization of chipless RFID tags comprising fractal structures

  Yuta Watanabe, Hajime Igarashi

  INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS 52 (1-2) 609 - 616 1383-5416 2016 [Refereed][Not invited]
   

  This paper discusses the shape optimization of chipless radio frequency identification (RFID) tags comprising fractal structures. In the proposed optimization process, scattering electromagnetic waves from a chipless RFID tag are analyzed using a finite-difference time-domain (FDTD) method. The shapes of the chipless RFID tags are optimized by a micro-genetic algorithm (m-GA) to determine the frequencies of the subject scattering waves, as well as to maximize their associated amplitudes and quality factors. As such, a self-similar metal line and metal patch comprising fractal structures are assumed to be a chipless RFID tag. The optimized tags obtained using the FDTD method and m-GA ultimately maintain the selective frequencies, high amplitudes, and quality factors of the scattering electromagnetic waves.
• Topology optimization of wideband array antenna for microwave energy harvester

  Takuya Mori, Hajime Igarashi

  INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS 52 (1-2) 631 - 639 1383-5416 2016 [Refereed][Not invited]
   

  This paper presents optimal shape design of planar array antennas for microwave energy harvesters. The topology optimization of the C-4-symmetric array antenna is conducted to maximize their isotropic gain and minimize the return losses in a frequency band ranging from 1.5 to 3.5 GHz. Then, we design the rectifier by varying the circuit parameter based on measurement results to realize the impedance matching between the optimized antenna and rectifier. It is shown by experiment that the harvester composed of the optimized array antenna and rectifier has higher receiving voltage in comparison with the single one. Moreover, the resultant harvester is found to start operating when the arrival electric field is greater than 0.1 V/m.
• Direct synthesis of equivalent circuits from reduced FE models using proper orthogonal decomposition

  Toshihito Shimotani, Yuki Sato, Hajime Igarashi

  COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING 35 (6) 2035 - 2044 0332-1649 2016 [Refereed][Not invited]
   

  Purpose - The purpose of this paper is to propose a fast synthesis method of the equivalent circuits of electromagnetic devices using model order reduction. Finite element method (FEM) has been widely used to design electromagnetic devices. For FE analysis of these devices connected to control and deriving circuits, FE equations coupled with the circuit equations have to be solved for many times in their design processes. If the FE models are replaced by equivalent circuit models, computational time could be drastically reduced. Design/methodology/approach - In the proposed method, a reduced FE model is obtained using proper orthogonal decomposition (POD) in which the size of FE equation is effectively reduced so that the computational time for FE analysis is shortened. Then, the equivalent circuits are directly synthesized from the admittance function of the reduced system. Findings - Accuracy and computational efficiency of the proposed method are compared with those of another POD-based method in which the equivalent circuits are synthesized from fitting of frequency characteristics using optimization algorithm. There are no significant differences in the accuracy of both methods, while the speedup ratio of the former method is found larger than that for the latter method for the same sampling points. Originality/value - The equivalent circuits of electric machines and devices have been synthesized on the basis of physical insight of engineers. This paper proposes a novel method by which the equivalent circuits are automatically synthesized from FE model of the electric machines and devices using POD.
• Optimal Design of RF Energy Harvesting Device Using Genetic Algorithm

  T. Mori, Y. Sato, R. Adriano, H. Igarashi

  Sensing and Imaging 16 (1) 1573-9317 2015/11/04 [Refereed][Not invited]
   

  This paper presents optimal design of an RF energy harvesting device using genetic algorithm (GA). In the present RF harvester, a planar spiral antenna (PSA) is loaded with matching and rectifying circuits. On the first stage of the optimal design, the shape parameters of PSA are optimized using $$\\mu {\\rm GA}$$μGA. Then, the equivalent circuit of the optimized PSA is derived for optimization of the circuits. Finally, the parameters of RF energy harvesting circuit are optimized to maximize the output power using GA. It is shown that the present optimization increases the output power by a factor of five. The manufactured energy harvester starts working when the input electric field is greater than 0.5 V/m.
• Robust Optimization Considering Probabilistic Magnetic Degradation

  Yuki Hidaka, Shintaro Furui, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 51 (3) ROMBUNNO.7401204  0018-9464 2015/03 [Not refereed][Not invited]
   

  This paper presents robust topology optimization of electromagnetic machines by considering the magnetic degradation caused by mechanical and thermal stresses in punching, shrinking fitting, and other manufacturing processes. The topology optimization is performed using two methods: one is the robust genetic algorithm in which random noises are added to the magnetic characteristic parameters and the other takes the deviations in the objective and constraint functions due to the degradation into account. These methods are applied to optimization of the flux barrier shapes in an interior permanent magnetic motor to find that one can successfully realize robust design.
• Fast Shape Optimization of Antennas Using Model Order Reduction

  Yuki Sato, Felipe Campelo, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 51 (3) ROMBUNNO.7204304  0018-9464 2015/03 [Refereed][Not invited]
   

  This paper presents a fast shape optimization method for antennas using proper orthogonal decomposition (POD)-based model order reduction (MOR). In this method, the finite element region is subdivided into design and ambient regions. The former includes antennas, whose shapes are optimized, whereas the latter includes air and perfect matched layer. Since the electromagnetic fields significantly change in the design region during the optimization process, POD-based MOR is only applied to the ambient region. In addition, MOR for both shape and frequency responses is performed for optimization of wideband antennas. It is shown that the present method can effectively reduce the computational time without deteriorating performance in the optimization.
• Shape Optimization of Wideband Antennas for Microwave Energy Harvesters Using FDTD

  Takuya Mori, Ryo Murakami, Yuki Sato, Felipe Campelo, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 51 (3) ROMBUNNO.8000804  0018-9464 2015/03 [Refereed][Not invited]
   

  This paper presents parameter and topology optimizations of wideband antennas for microwave energy harvesters based on finite difference time-domain computations. The antenna shapes are optimized to reduce return losses in a specific frequency band using micro-genetic algorithm. The shape parameters of a two-arm planar spiral antenna are optimized. In addition, the topology optimization is performed using normalized Gaussian network, where spatial symmetries are assumed. It is shown that the return losses of the optimized antennas are <-10 dB from 1 to 2 GHz in which they have isotropic directivity.
• Multimaterial Topology Optimization of Electric Machines Based on Normalized Gaussian Network

  Takahiro Sato, Kota Watanabe, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 51 (3) ROMBUNNO.7202604  0018-9464 2015/03 [Refereed][Not invited]
   

  This paper presents a topology optimization method for multimaterial models based on the normalized Gaussian network. In this method, one can determine optimal shapes of machines that are composed of various materials, such as iron, magnetic, and nonmagnetic material. The present method is applied to the optimization of the average torque for interior permanent magnet motor to determine the distributions of magnetic core and flux barrier as well as magnets. The optimization results show that average torque can be improved using as small amount of magnet as possible. In addition, the characteristic of the present method is discussed in detail.
• Loss Computation of Soft Magnetic Composite Inductors Based on Interpolated Scalar Magnetic Property

  Takahiro Sato, Soichiro Aya, Hajime Igarashi, Michiaki Suzuki, Yoshiki Iwasaki, Kenji Kawano

  IEEE TRANSACTIONS ON MAGNETICS 51 (3) ROMBUNNO.8001704  0018-9464 2015/03 [Refereed][Not invited]
   

  This paper presents a new loss computation method for soft magnetic composite (SMC), which allows us to evaluate the loss for wide operating conditions. A formula for evaluation of eddy current and hysteresis losses is introduced. The effective volume fraction of the magnetic grain is determined from the sampled measured data. It is shown that the formula provides accurate estimate of the total loss in a toroidal SMC core. In addition, the loss of SMC inductor is shown to be also accurately evaluated at small computational burden using the proposed method.
• Topology Optimization of Synchronous Reluctance Motor Using Normalized Gaussian Network

  Shunpei Sato, Takahiro Sato, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 51 (3) ROMBUNNO.8200904  0018-9464 2015/03 [Refereed][Not invited]
   

  This paper presents the topology optimization of a synchronous reluctance motor using the normalized Gaussian network. In the optimization, the average torque and iron loss are considered. In the resultant motor, the area of the rotor surface adjacent to the stator is found to be reduced when the weight for the iron loss is sufficiently large. On the other hand, large flux barriers are present in the rotor when the average torque is maximized without considering the iron loss.
• Numerical Simulation of DC SQUID Taking Into Account Quantum Characteristic of Josephson Junction

  Naoya Terauchi, So Noguchi, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 51 (3) ROMBUNNO.7202804  0018-9464 2015/03 [Not refereed][Not invited]
   

  High-temperature superconducting quantum interference devices (HTS SQUIDs) have been developed as an extremely sensitive magnetic sensor. The HTS SQUIDs are required to have high robustness with respect to the magnetic noise for stable operation in an unshielded environment and also reduced cost to widen the application range. It is, therefore, necessary to clarify the quantum magnetic behavior of the HTS SQUID. However, a simulation tool, which can consider the quantum magnetic behavior, has not been developed yet. In this paper, an equivalent circuit of a Josephson junction comprising the HTS SQUID is more properly considered to represent the quantum behavior. It can consider the ac and dc Josephson effect. The obtained results are compared with an ordinary simulation using a simplified circuit model, and the results agree well with each other. Using the proposed simulation method instead of the ordinary simulation, the current path is more accurately simulated, so this new method will be used to evaluate the robustness of the SQUID.
• Shape optimization of rotor in interior permanent magnet motor based on topology optimization method using normalized gaussian network

  Takahiro Sato, Hajime Igarashi, Shinya Takahashi, Syo Uchiyama, Keisuke Matsuo, Daiki Matsuhashi

  IEEJ Transactions on Industry Applications The Institute of Electrical Engineers of Japan 135 (3) 291 - 298 1348-8163 2015/03/01 [Refereed][Not invited]
   

  This paper presents a new topology optimization method based on normalized Gaussian network (NGnet). In this method, the machine region is subdivided into small elements whose material states are determined from the output of NGnet so that the objective function is extremized under the given constraints. The present method is applied to shape optimization of the rotor in an interior permanent magnet motor. The rotor shape is optimized to minimize the torque ripple while keeping the average torque. It is shown that the optimization halves the torque ripple while the average torque remains unchanged. This result was validated through a comparison between the computed and measured torques.
• A chaotic vibration energy harvester using magnetic material

  Takahiro Sato, Hajime Igarashi

  Smart Materials and Structures 24 (2) 025033,1-8  0964-1726 2015/02 [Refereed][Not invited]
   

  This paper presents a new wideband electromagnetic vibration energy harvester (VEH) composed of a magnetic core embedded into the coil axis. The magnetic core generates a nonlinear magnetic force, which gives rise to the nonlinearity in the behavior of the VEH. Moreover, the magnetic core increases the flux linkage with the coil. These features improve the operational bandwidth and output power of the VEH. Numerical analysis and experimental measurements reveal that the operational bandwidth of the proposed VEH is over 30 Hz in which the output power is kept about 0.1 mW. Moreover, the proposed VEH operates by complicated oscillation due to nonlinear forces acting on the oscillator. Evaluation of the Lyapunov exponent for the measured oscillation suggests that the proposed VEH produces chaotic oscillation.
• Optimization of sensor network topology in deployed in inhomogeneous lossy media

  Rony Teguh, Hajime Igarashi

  Telkomnika (Telecommunication Computing Electronics and Control) 13 (2) 469 - 477 2302-9293 2015 

  This paper presents optimization of wireless sensor network (WSN) topology for forest fire detection. The sensors for this purpose are deployed in forest, grassland and open space, which have different attenuation properties in electromagnetic waves. For this reason, routers which receive signals from sensors and send them to the base station must be deployed considering these differences. In this work, we develop an optimization method for WSN topology based on simulated annealing considering the differences in the attenuation property. The vegetation data are taken from Landsat data. Using the present method, the necessary number of routers for full connection of the sensors deployed in diverse, irregular environments can be estimated.
• Numerical Analysis of Electromagnetic Wave Propagation in Forest

  TEGUH Rony, SATO Yuki, IGARASHI Hajime

  Journal of the Japan Society of Applied Electromagnetics and Mechanics The Japan Society of Applied Electromagnetics and Mechanics 23 (1) 131 - 136 0919-4452 2015 

  Wireless sensor networks (WSN) are effective to detect peat and forest fires which can give significant damages in environment and economics. To determine optimal network topology of WSN, one has to know characteristics of electromagnetic wave propagation in forest. In this work, the attenuation constant of waves is evaluated from complex permittivity and basal area of the forest using homogenization technique. It is possible to evaluate the attenuation constant from the measured permittivity of tree trunks and the basal area.
• Deflated Conjugate Gradient Method for Magnetostatic Analysis

  Watanabe Kota, Igarashi Hajime

  JASSE Japan Society for Simulation Technology 1 (1) 211 - 216 2188-5303 2015 

  The deflated conjugate gradient (CG) method which can improve the convergence of CG is discussed. The distorted finite element mesh produces the system matrix with a large condition number, which results in poor convergence of CG method. The deflation technique replaces small eigenvalues with zeros in the system matrix. Therefore the deflated CG method is a useful solver for such ill-conditioned finite element analyses. However, the computational cost to obtain the eigenvectors is significantly high. To solve this problem, quasi eigenvectors which can be obtained with low cost are used in this paper. Moreover, the robustness of deflated CG method against distorted finite mesh with flat elements which bring ill-condition is presented.
• 調査研究委員会レポート：先進電磁界解析による設計高度化技術調査専門委員会

  五十嵐 一, 阿波根 明, 岡本 吉史, 米津 大吾

  電気学会論文誌. B The Institute of Electrical Engineers of Japan 135 (3) NL3_25 - NL3_25 0385-4213 2015
• Model order reduction for moving objects: fast simulation of vibration energy harvesters

  Takahiro Sato, Yuki Sato, Hajime Igarashi

  COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING 34 (5) 1623 - 1636 0332-1649 2015 [Refereed][Not invited]
   

  Purpose - The finite element method (FEM) for 3D models needs heavy computational cost. The computational cost for FE analysis of moving objects, e.g. Vibration energy harvester, must be reduced to exploit the simulation of the dynamic system in its design. The paper aims to discuss these issues. Design/methodology/approach - To reduce the computational time of FEM, the model order reduction (MOR) based on proper orthogonal decomposition has been proposed. For the moving systems, MOR is modified. Findings - It is shown that proposed MOR makes it possible to drastically reduce the coupling analysis of the energy harvester in which the equations of motion, magnetostatics, and circuit are repeatedly solved. Originality/value - To reduce the computational time of FEM, block-MOR is presented, in which the whole domain is subdivided into N-blocks. As a result computational cost for MOR can be reduced.
• ON LEVELSET AND EVOLUTIONARY ON/OFF METHODS FOR TOPOLOGY OPTIMIZATION IN MAGNETOSTATIC PROBLEMS

  SATO TAKAHIRO, WATANABE KOTA, IGARASHI HAJIME

  計算数理工学論文集 日本計算数理工学会 14 13 - 18 1348-5245 2014/12 [Refereed][Not invited]
  
• Topology Optimization Method Based on On-Off Method and Level Set Approach

  Yuki Hidaka, Takahiro Sato, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 50 (2) 0018-9464 2014/02 [Refereed][Not invited]
   

  This paper proposes a two-step method for topology optimization, in which after global search is performed by the on-off method, and then local search is carried out by the level set approach. The genetic and gradient-based algorithms are employed for the former and latter optimizations, respectively. This present method is applied to two numerical examples; topology optimizations of a magnetic shield system and interior permanent magnetic motor. It is shown that this present method can find solutions with better performances in comparison with the conventional on-off method.
• Coupled Analysis of Electromagnetic Vibration Energy Harvester With Nonlinear Oscillation

  Takahiro Sato, Kota Watanabe, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 50 (2) 0018-9464 2014/02 [Refereed][Not invited]
   

  This paper presents a coupled analysis of electromagnetic vibration energy harvester (VEH) on the basis of the nonconforming voxel FEM. In this analysis method, the motion, Maxewell, and circuit equations are alternatively solved using the staggered method. The FE models can be generated in this method with low computational costs. By using the coupled analysis method, the characteristics of a VEH model, which contains the magnetic material in the coil, is analyzed changing the geometric parameters. It is shown from the analysis results that the VEH model has chaotic and linear oscillations. It is also shown that output power can be generated for a wide frequency range in the chaotic mode, and in the linear mode, large output power is obtained at the resonance.
• Matching of Antenna by Electromagnetic Analysis Technique

  ITOH Keiichi, KOMATSU Kaoru, MIYATA Katsumasa, IGARASHI Hajime

  Journal of the Japan Society of Applied Electromagnetics and Mechanics 2014 [Refereed][Not invited]
   

  The impedance matching is an important technique for the improvement of the transmission efficiency of the waveguide slot array antenna with the dielectric lenses. We apply the electromagnetic field analysis technique to the impedance matching method by inserting the tuning screw into the waveguide wall. To reduce the VSWR over the frequency band, the optimization method of the tuning screw by the μGA is proposed. The objective function of the μGA is calculated by the FDTD method. From the calculation results, the VSWR in the frequency range from 11.8 to 12.2 GHz is improved by optimizing the screw parameters. The antenna matching by the μGA shows good performance as compared with that by the conventional method. Also, the validity of the proposed method is confirmed by the measurement result.
• Experimental and simulation modeling studies of magnetic properties of Ni-Zn ferrite cores under dc bias

  H. Oshima, Y. Uehara, K. Shimizu, K. Inagaki, A. Furuya, J. Fujisaki, M. Suzuki, K. Kawano, T. Mifune, T. Matsuo, K. Watanabe, H. Igarashi

  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy 61 (S1) S238 - S241 0532-8799 2014 [Refereed][Not invited]
   

  Ni-Zn ferrite cores under dc bias are experimentally characterized, and the results are compared with those of simulation. Hysteretic behavior of a toroidal core at high frequencies and the effect of dc bias are well reproduced by simulation with a hysteresis model that we have developed recently, a grain magnetics (GM) model. The inductance and core loss of a wirewound inductor under high-frequency excitation with dc bias are also measured. We show that the finite element analysis with the hysteresis model provides simulation results close to the experimental data of the inductor.
• DC bias effect on the magnetic properties in NiZn ferrite

  M. Suzuki, K. Kawano, T. Matsuo, T. Mifune, Y. Uehara, A. Furuya, H. Igarashi, K. Watanabe

  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy 61 S245 - S247 0532-8799 2014 [Refereed][Not invited]
   

  Magnetic properties of mono-domain and multi-domain NiZn ferrites under dc magnetic flux densities were investigated with regard to actual performance in power circuits. Bias properties were measured along the initial magnetization curve. The magnetizing process in the multi-domain sample is mainly dominated by domain-wall motion even in the low ac magnetic flux density region. In contrast, in the mono-domain sample, magnetization is reversible and core loss is low regardless of the dc magnetic flux density because the spin rotation dominates if ac flux density is below 20 mT.
• Optimization of Router Deployment for Sensor Networks Using Genetic Algorithm

  Rony Teguh, Ryo Murakami, Hajime Igarashi

  ARTIFICIAL INTELLIGENCE AND SOFT COMPUTING ICAISC 2014, PT I 8467 468 - 479 0302-9743 2014 [Refereed][Not invited]
   

  This paper presents optimization of router deployment based on genetic algorithm for energy- constrained wireless sensor networks which are used for wildfire monitoring. The router positions are optimized so that the total communication distance is minimized to maximize the lifetime of the sensor network. To consider the real geographical features of the target field, the elevation differences are included in fitness evaluation. It is shown that one can reduce the total communication distance as well as the number of disconnected sensors for both flat and irregular terrains using the present optimization method.
• A Bistable Vibration Energy Harvester with Closed Magnetic Circuit

  Takahiro Sato, Takeshi Sugisawa, Hajime Igarashi

  14TH INTERNATIONAL CONFERENCE ON MICRO AND NANOTECHNOLOGY FOR POWER GENERATION AND ENERGY CONVERSION APPLICATIONS (POWERMEMS 2014) 557 1742-6588 2014 [Refereed][Not invited]
   

  In this work, to increase magnetic flux passing through the electric coil in a bistable vibration energy harvester, the magnetic circuit is made closed by introducing two coil systems which have magnetic core in their axis holes. The magnetic resistance of the magnetic circuit, composed of silicon steel and thin air gaps, is supressed to be small. The double well potential is realized from the spring force and nonlinear magnetic force between the magnets and the magnetic core. Two harvesters with opened and closed magnetic circuits are manufactured for comparison. It is also shown that the closed magnetic circuit can effectively improve the output power.
• Design Optimization Based on Electromagnetic Field Analysis Toward Computer-Aided Invention

  IGARASHI Hajime

  IEEJ Transactions on Sensors and Micromachines The Institute of Electrical Engineers of Japan 134 (10) 700 - 703 1340-5551 2014 [Not refereed][Invited]
   

  電磁界解析による設計最適化：Computer-Aided Inventionに向けて 五十嵐 一
• Electromagnetic Vibration Energy Harvester: Wideband Generation via Nonlinear Oscillation

  SATO Takahiro, IGARASHI Hajime

  Journal of the Japan Society of Applied Electromagnetics and Mechanics 日本AEM学会 22 (3) 374 - 379 0919-4452 2014 [Not refereed][Invited]
   

  This paper reports an electromagnetic vibration energy harvester with magnetic material in which nonlinear oscillation results in broadband operation frequency range for power generation. Moreover, the present harvester is shown to have double-well potential which yields chaotic oscillation.
• Accuracy evaluation of three-dimensional FE analysis based on nonconforming voxel element

  Takahiro Sato, Kota Watanabe, Hajime Igarashi

  COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING 33 (1-2) 181 - 190 0332-1649 2014 [Refereed][Not invited]
   

  Purpose - Three-dimensional (3D) mesh generation for shape optimizations needs long computational time. This makes it difficult to perform 3D shape optimizations. The purpose of this paper is to present a new meshing method with light computational cost for 3D shape optimizations. Design/methodology/approach - This paper presents a new meshing method on the basis of nonconforming voxel finite element method. The 3D mesh generation is performed with light computational cost keeping the computational accuracy. Findings - It is shown that the computational cost for 3D mesh generation can be reduced without deteriorating numerical accuracy in the FE analysis. It is reported the performance of the present method. Originality/value - The validity of the nonconforming voxel elements is tested to apply it to the optimization of 3D optimizations.
• Stochastic topology optimization based on level-set method

  Yuki Hidaka, Takahiro Sato, Kota Watanabe, Hajime Igarashi

  COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING 33 (6) 1904 - 1919 0332-1649 2014 [Refereed][Not invited]
   

  Purpose - Conventional level-set method tends to fall into local optima because optimization is conducted based on gradient method. The purpose of this paper is to develop a novel topology optimization in which simulated annealing (SA) is introduced to overcome the difficulties in level-set method. Design/methodology/approach - Level-set based topology optimization for two-dimensional optimization problem. Findings - It is shown in the numerical examples, where conventional and present methods are applied to shape optimization of ferrite inductor and Interior Permanent Magnetic (IPM)-motor, the present method can find solutions with better performance than those obtained by the conventional method. Originality/value - SA is introduced to improve the search performances of level-set method.
• A modified immune algorithm with spatial filtering for multiobjective topology optimisation of electromagnetic devices

  Takahiro Sato, Kota Watanabe, Hajime Igarashi

  COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING 33 (3) 821 - 833 0332-1649 2014 [Refereed][Not invited]
   

  Purpose - In the development of electromagnetic devices, multiobjective topology optimisation is effective to obtain diverse design candidates for production models. However, multiobjective topology optimisation has not widely been performed because it is difficult to obtain resultant shapes for engineering realisation due to large search spaces. The purpose of this paper is to present a new multiobjective topology optimisation method. Design/methodology/approach - This paper presents a new multiobjective topology optimisation method in which the Immune Algorithm is modified for multiobjecrive optimisation and a shape modification process based on spatial filtering is employed. Findings - The present method shows that better Pareto solutions can be found in comparison with the conventional methods. Originality/value - A new effective multiobjective topology optimisation is presented. This method enables to diverse design candidates for production models.
• Multi-Objective Shape Optimization of IPM-Motors Using On-Off Method Coupled With Level-Set Method

  Hidaka Yuki, Igarashi Hajime

  Transaction of the Japan Society for Simulation Technology 日本シミュレーション学会 6 (3) 37 - 42 1883-5031 2014 [Refereed][Not invited]
   

  This paper introduces a new method for multi-objective topology optimization problems. The present method is composed of two steps: global search based on genetic algorithm (GA), which is followed by local search using a gradient-based method. In the global search, the design region is subdivided into small elements, to which either of two states, On (material) or Off (non-material) is assigned. In the optimization process based on multi-objective GA, diverse device shapes are generated by changing these states independently to obtain Pareto solutions. In order to improve performance of the devices corresponding to the Pareto solutions, local search based on the level-set method is performed starting from those solutions.   The present method is applied to multi-objective design problem of IPM (Interior permanent magnet motor). The goal of this design is to maximize the average torque and minimize torque ripple. It is shown from the numerical results that the quality of the Pareto solutions can be improved by the local search. Moreover, it is found that manufacture of the optimized rotor becomes easier after the local search because small flux barriers disappear and the surface of the remained flux barriers becomes smooth. It is possible to obtain diverse IPM motors which have different average torques and torque ripples by the present method. The present method, therefore, gives useful information for the design of devices and machines.
• Computation of Macroscopic Electromagnetic Properties of Soft Magnetic Composite

  Yasuhisa Ito, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 49 (5) 1953 - 1956 0018-9464 2013/05 [Refereed][Not invited]
   

  This paper presents a new numerical method to compute the macroscopic electromagnetic properties of the soft magnetic composite (SMC). In present method, SMC is assumed to be composed of homogeneous magnetic bricks with periodicity. The macroscopic electromagnetic properties of SMC are obtained using the finite element method in which it is assumed that the homogenized energy is equal to that stored in a unit domain. We compare the macroscopic electromagnetic properties obtained by the present method with those obtained by Ollendorf's formula and magnetic circuit based on the nonmagnetic grain boundary model. It is shown that the three results are in good agreement when assuming constant permeability. It is also found that there are clear discrepancies among them due to magnetic saturations especially when the demagnetization coefficient is large.
• Shape Optimization of Double Antenna for Long Range Passive UHF-Band RFID

  Yuta Watanabe, Kota Watanabe, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 49 (5) 2133 - 2136 0018-9464 2013/05 [Refereed][Not invited]
   

  The passive RFID tag, which receives energy for its operation from electromagnetic waves radiated by RFID readers, changes the antenna impedance to modulate the back scattering waves caught by the reader. For this reason, during the back-scattering communication, the energy received by the RFID tag much reduces due to the impedance mismatch. To resolve this problem, the double antenna system which consists of receiving and sending antennas has been proposed. In this paper, the double antenna shapes are optimized on the basis of FDTD analysis and genetic algorithm to maximize the communication distance.
• Model Reduction of Three-Dimensional Eddy Current Problems Based on the Method of Snapshots

  Yuki Sato, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 49 (5) 1697 - 1700 0018-9464 2013/05 [Refereed][Not invited]
   

  The model reduction based on the method of snapshots is applied to the finite element analysis of three-dimensional transient eddy current problems. It is known that accuracy of the reduced model highly depends on the number of snapshots. In this paper, we introduce a novel method which determines the adequate number of snapshots automatically. It is shown that the computational time can be reduced when using the model reduction based on the present method.
• Performance of 3-D Infinite Elements for High-Frequency Electromagnetic Fields

  Yuta Watanabe, Yuki Sato, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 49 (5) 1673 - 1676 0018-9464 2013/05 [Refereed][Not invited]
   

  The infinite elements for edge based finite-element methods (FEMs) have been shown effective for open boundary problems. In the infinite elements, electromagnetic fields are expressed in terms of radially decaying basis functions. On the other hand, the perfect matched layer has widely been used for FEMs for high-frequency problems. In this paper, numerical performance of both methods is comparably discussed. The numerical experiments show that the former has higher computational efficiency.
• 3-D Optimization of Ferrite Inductor Considering Hysteresis Loss

  T. Sato, K. Watanabe, H. Igarashi, T. Matsuo, T. Mifune, K. Kawano, M. Suzuki, Y. Uehara, A. Furuya

  IEEE TRANSACTIONS ON MAGNETICS 49 (5) 2129 - 2132 0018-9464 2013/05 [Refereed][Not invited]
   

  This paper presents three-dimensional shape optimization of inductors for the dc-dc converters, in which the nonconforming voxel-based finite element method (FEM) is employed to realize fast FE mesh generation during the optimization. The operating point of the inductor under the bias current condition, which is estimated from the circuit analysis, is obtained by nonlinear FE analysis. Then, the FE equation linearized around the operating point is solved being coupled with the circuit equation to obtain the magnetic fields in the inductor. The hysteresis loss is computed from the Steinmetz formula. Validity of the field computation is tested by comparing the numerical results with measured data. The multiobjective optimization of the inductor shapes is performed to minimize the winding resistance and hysteresis loss. It is shown that the present method can effectively find the Pareto solutions which can lead to improvement in the efficiency of the dc-dc converter.
• Equivalent circuit modeling of DC and AC ferrite magnetic properties using H-input and B-input play models

  S. Ito, T. Mifune, T. Matsuo, K. Watanabe, H. Igarashi, K. Kawano, Y. Iijima, M. Suzuki, Y. Uehara, A. Furuya

  IEEE Transactions on Magnetics Institute of Electrical and Electronics Engineers 49 (5) 1985 - 1988 0018-9464 2013/05 [Refereed][Not invited]
   

  An equivalent circuit model is proposed to represent ferrite magnetic properties under ac and dc fields phenomenologically, where the H-input and B-input play models are used to handle hysteretic property accurately and concisely. A slow magnetization component is extracted from measured ac and dc properties. Frequency dependence of the ac loss is represented by an equivalent resistance. The simulated ac and dc magnetic properties agree with the measured properties.
• Numerical simulation of screening current distribution in HTS tape of high field magnet

  Ryusei Itoh, Yuki Oga, So Noguchi, Hajime Igarashi, Hiroshi Ueda

  Physica C: Superconductivity and its Applications 484 300 - 304 0921-4534 2013/01/15 [Refereed][Not invited]
   

  In recent years, properties of high temperature superconducting (HTS) tapes, especially in-field performance and mechanical strength, have been continuously improved. The HTS tapes have been widely used for high field (> 20 T) magnet researches and there are several technical challenges including field attenuation of an HTS magnet by screening currents induced within the HTS tapes. Several publications reported that the screening currents, induced by penetration of self magnetic fields into HTS tapes within an HTS magnet, weakened a field constant of the HTS magnet. The result may demonstrate that the screening current changes an overall current density distribution in HTS tapes and, as a consequence, the generated magnetic field. Therefore, it is necessary to investigate the screening current distribution in an HTS tape. This paper reports numerical simulation of the screening current distribution in an HTS tape of high field magnets using 2D finite element method with the E-J characteristic of the HTS tape taken into account. Self magnetic field distribution and its orientation to the HTS tape are also considered to compute critical currents and locally generated electric fields, two key components to figure out the distribution of screening currents.
• Meander line antenna design using an adaptive genetic algorithm

  Yuki Sato, Felipe Campelo, Hajime Igarashi

  IEEE Transactions on Magnetics 49 (5) 1889 - 1892 0018-9464 2013 [Refereed][Not invited]
   

  This paper presents the optimization of a meander line antenna finite-element model by means of an adaptive genetic algorithm (GA). To search for optimal antenna configurations, the present method employs a GA with an adaptive method that adjusts the characteristics of its selection, crossover, and mutation operators in order to maintain a diverse set of high-quality candidate solutions during its execution. It is shown that the present method can find an optimal solution faster than the conventional GA. Moreover, the fitness values of the optimal solutions obtained by the present method are better than those obtained by conventional GA. © 1965-2012 IEEE.
• A new mesh smoothing method to improve the condition number of submatrices of coefficient matrix in edge finite element method

  So Noguchi, Atsushi Takada, Fumiaki Nobuyama, Masahiko Miwa, Hajime Igarashi

  IEEE Transactions on Magnetics 49 (5) 1705 - 1708 0018-9464 2013 [Refereed][Not invited]
   

  A common mesh smoothing method strives to improve the shape quality of all elements. Generally a mesh consisting of only well-shaped elements is desired in finite element analysis. Although a perfect-shaped element yields short computation time, even a well-shaped element, whose shape is close to a regular polygon, sometimes prolongs the computation time of solving the system of equations derived with the edge-based finite element method. In this paper, we propose a new smoothing scheme of improving a convergence property of the system of equations by applying a common mesh smoothing method to some elements, which cause long computation time of the iterative solver. The proposed smoothing scheme utilizes the condition number of submatrices, into which coefficient matrix derived with the edge-based finite element method is subdivided, in order to choose ill-conditioned elements to be smoothed. As a result, the computation time is shortened applying a smoothing process only to the chosen ill-conditioned elements. © 1965-2012 IEEE.
• A New Wideband Electromagnetic Vibration Energy Harvester with Chaotic Oscillation

  Takahiro Sato, Hajime Igarashi

  13TH INTERNATIONAL CONFERENCE ON MICRO AND NANOTECHNOLOGY FOR POWER GENERATION AND ENERGY CONVERSION APPLICATIONS (POWERMEMS 2013) 476 1742-6588 2013 [Refereed][Not invited]
   

  This paper presents a new electromagnetic vibration energy harvester (VEH) which harvests the electric power in wide frequency range. The present VEH contains the ferrite core embedded in the axis hole of the coil bobbin which generates the magnetic force acting on the oscillator. The performance of the present VEH is estimated using the coupled analysis method for VEH in which motion, Ampere, and circuit equations are alternatively solved until convergence. Using the coupled analysis method, the output power characteristic in the present VEH against input frequency is analyzed. It is shown from the analysis results that the present VEH has chaotic oscillation and wide frequency range for power generation. Moreover, the condition that the present VEH has nonlinear oscillation is discussed.
• Robust optimization of patch antennas considering non-linear circuit for UHF-band passive RFID

  Yuta Watanabe, Hajime Igarashi

  INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS 43 (1-2) 77 - 84 1383-5416 2013 [Refereed][Not invited]
   

  This paper presents shape optimization of patch antennas loaded by the Cockcroft-Walton (CW) circuit for UHF-band passive RFID tags. In the present optimization, the antenna characteristics are analyzed by hybridization of the finite-difference time-domain method and modified nodal method. To accelerate the convergence to the steady state, the unknowns are decomposed into the fast and slowly convergence components, which are separately determined. The shape of patch antennas is optimized by using the micro genetic algorithm in order to maximize the output voltage of the CW circuit and obtain high robustness against the shape changes. The optimized antenna has higher output voltage of the CW circuit in comparison with the half-wave patch antenna.
• Classification and Size Estimation of Wafer Defects by Using Scattered Light Distribution

  Sugihara Yoshihiko, Honda Toshifumi, Urano Yuta, Watanabe Masahiro, Noguchi So, Igarashi Hajime

  IEEJ Transactions on Electronics, Information and Systems 一般社団法人 電気学会 133 (11) 2118 - 2124 0385-4221 2013 [Not refereed][Not invited]
   

  Usually, there are two processes in wafer inspection. One is detection of defects on a wafer, which is very important. The other is classification of the detected defects, which is done after defect detection as necessary. Recently, it has been necessary to simultaneously detect and classify defects on wafers in order to shorten the wafer inspection time with high resolution. Optical wafer inspection is the most effective method for detecting and classifying a defect and estimating its size in a short time. Optical wafer inspection utilizing scattered light distribution can easily detect and classify a defect since the distribution depends on both the type and size of the defect. The measured scattered light distribution is compared with a database of the previous scattered light distributions using pattern matching in order to classify the defect and estimate its size. Therefore, to achieve optical wafer inspection with scattered light distribution, it is necessary to gather scattered light distribution data for many various samples.The first aim of this study is to develop a defect classification and size estimation method utilizing scattered light distribution. We propose a way for classifying a defect on a wafer and estimating its size. The proposed method uses pattern matching utilizing a parametric eigenspace. The second aim of the paper is to validate the proposed method by applying it to scattered light distribution samples. The light scattering distribution samples are generated by Discrete Dipole Approximation (DDA) simulation. The database of the light scattering distributions is easily created using the simulation.
• Magnetic field analysis in far-field region by infinite edge element with boundary surface integration

  T. Yoshioka, Y. Tawada, K. Tsuzaki, S. Wakao, A. Kameari, T. Tokumasu, Y. Takahashi, H. Igarashi, K. Fujiwara

  IEEE Transactions on Magnetics 49 (5) 1681 - 1684 0018-9464 2013 [Refereed][Not invited]
   

  The electromagnetic phenomena intrinsically spread over the infinite space. Thus, the efficient handling of the open boundary is one of the main issues in the electromagnetic field computation. This paper proposes the infinite edge element method (IEEM) with the boundary surface integration to accurately obtain the magnetic field, i.e., the derivatives of vector potentials, in the far-field region. © 1965-2012 IEEE.
• Computational accuracy enhancement in magnetic field analysis by using orthogonalized infinite edge element method

  Kenta Tsuzaki, Yoshihiro Tawada, Shinji Wakao, Akihisa Kameari, Tadashi Tokumasu, Yasuhito Takahashi, Hajime Igarashi, Koji Fujiwara, Yoshiyuki Ishihara

  IEEJ Transactions on Power and Energy 133 (5) 8 - 472 0385-4213 2013 [Refereed][Not invited]
   

  The electromagnetic phenomena intrinsically spread over the infinite region. Thus, the efficient handling of open boundary is one of the main issues in the electromagnetic field computations. This paper deals with the orthogonalized infinite edge element method which efficiently performs precise analysis of the infinite region. In this method, there are several parameters to achieve its high accuracy. As one of the parameters, we focus on the reference point and investigate the effect of its position setting on the accuracy. Furthermore, we also evaluate the accuracy of the calculated magnetic field at distance region. By applying boundary element method (BEM) as post-processing, it is found that the high computational accuracy in the region can be effectively achieved. © 2013 The Institute of Electrical Engineers of Japan.
• Model-based defect detection in multidimensional vector spaces

  Toshifumi Honda, Kenji Obara, Minoru Harada, Hajime Igarashi

  ELECTRONICS AND COMMUNICATIONS IN JAPAN 95 (9) 44 - 53 1942-9533 2012/09 [Refereed][Not invited]
   

  A highly sensitive inspection algorithm is proposed that extracts defects in multidimensional vector spaces from multiple images. The proposed algorithm projects subtraction vectors calculated from test and reference images to control the noise by reducing the dimensionality of vector spaces. The linear projection vectors are optimized using a physical defect model, and the noise distribution is calculated from the images. Because the noise distribution varies with the intensity or texture of the pixels, the target image is divided into small regions and the noise distribution of the subtraction images are calculated for each divided region. The bidirectional local perturbation pattern matching (BD-LPPM), which is an enhanced version of the LPPM, is proposed to increase the sensitivity when calculating the subtraction vectors, especially when the reference image contains more high-frequency components than the test image. The proposed algorithm is evaluated using defect samples for three different scanning electron microscopy images. The results reveal that the proposed algorithm increases the signal-to-noise ratio by a factor of 1.32 relative to that obtained using the Mahalanobis distance algorithm. (c) 2012 Wiley Periodicals, Inc. Electron Comm Jpn, 95(9): 4453, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.11390
• Simulation of Chain of Quenches on Toroidal HTS-SMES Taking Account of B - J - theta Characteristics

  Yuki Oga, So Noguchi, Hajime Igarashi

  IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 22 (3) 4701604,1-4  1051-8223 2012/06 [Not refereed][Not invited]
   

  Recently, many HTS-SMES systems have been designed and investigated in many countries. They usually consist of some superconducting element coils owing to effectively storing excessively high energy. If one of the superconducting element coils transition into a resistive state, the energy stored in the resistive superconducting element coil has to be immediately dispersed by a shunt resistor to prevent the superconducting conductor from burning. However, the electromagnetic behavior of the HTS-SMES with some resistive superconducting element coils has not yet been well investigated. Therefore, we have developed a simulation code to investigate the electromagnetic behavior of the HTS-SMES magnet after one or more superconducting element coils transitions into the resistive state. In the simulation, the magnetic field analysis and the electrical circuit analysis are coupled with the critical current calculation considering the B - J - theta characteristics of HTS tape. By the electromagnetic simulation, it is indicated that a chain of quenches is caused by the quench of one element coil.
• Voxel Based Finite Element Method Using Homogenization

  Kota Watanabe, Yosuke Iijima, Kenji Kawano, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 48 (2) 543 - 546 0018-9464 2012/02 [Refereed][Not invited]
   

  A homogenization technique in order to improve accuracy of finite element analyses with voxel mesh is proposed. The voxel mesh is one of the effective techniques to reduce costs of mesh generation. However, poor ability of expression for curved surfaces is a drawback to be solved and decreases the accuracy of finite element analyses. In this paper, a homogenization method for the voxel elements on the surfaces of magnetic objects is introduced. The anisotropic permeability determined by the present method improves the accuracy of analyses. The numerical results show that the proposed method has smaller errors of inductance in a three dimensional magnetostatic analysis in comparison with the conventional method.
• Evolutional Design of Waveguide Slot Antenna With Dielectric Lenses

  Keiichi Itoh, Katsumasa Miyata, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 48 (2) 779 - 782 0018-9464 2012/02 [Refereed][Not invited]
   

  This paper reports novel design method of waveguide slot array antenna with dielectric lenses by using the evolutionary optimization. We adopt the micro-genetic algorithm (MGA) with the real-coded gene as the optimization method and the finite-difference time-domain (FDTD) method to evaluate the objective function. The purpose of this study is to establish the design method of the above antenna by optimizing slot length and offset parameters. In the optimization of the antenna aperture distribution, it is shown that the optimized aperture field becomes sufficiently uniform, and the side-lobe levels (SLL) are improved in comparison with those of conventional antennas. Another optimization in which the objective function is evaluated by the array factor controls directly the side-lobe levels, to design low side-lobe antennas. By using the proposed method, the target antenna is optimized to satisfy the given SLL. It is confirmed that the proposed design method is a promising tool for designing the antennas loaded with dielectric materials.
• Orthogonalized Infinite Edge Element Method-Convergence Improvement by Orthogonalization of Hilbert Matrix in Infinite Edge Element Method

  S. Tamitani, K. Tsuzaki, Shinji Wakao, T. Tokumasu, Y. Takahashi, A. Kameari, H. Igarashi, K. Fujiwara, Y. Ishihara

  IEEE TRANSACTIONS ON MAGNETICS 48 (2) 363 - 366 0018-9464 2012/02 [Refereed][Not invited]
   

  This paper proposes an orthogonalization of the Hilbert matrix in element matrices of the infinite edge elements. The validity of the infinite edge element is demonstrated in previous researches, but the Hilbert matrix results in extremely slow convergence in the ICCG method, especially when using higher order expansions. The proposed orthogonalization technique improves the convergence drastically and it makes the infinite elements practical in the electromagnetic FEM analysis of the open boundary problems in quasi-static magnetic fields.
• An Improvement of Convergence in Finite Element Analysis With Infinite Element Using Deflation

  Hiroki Ito, Kota Watanabe, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 48 (2) 667 - 670 0018-9464 2012/02 [Refereed][Not invited]
   

  This paper presents a deflation technique to improve the convergence of finite element (FE) analyses with infinite elements. In FE analyses of electromagnetic fields, large air regions must be discretized into FE meshes. This leads to increases in computational time. The infinite element in which electromagnetic fields in air region are accurately expressed has been introduced in order to solve this problem. However, when using the infinite element, convergence of iterative liner solvers deteriorates because the condition number of FE matrices becomes large. In this paper, a deflation technique to improve convergence of iterative solvers is introduced. Numerical examples show that the proposed technique can improve convergence characteristics in a magnetostatic analysis with finite and infinite elements.
• Why Error Correction Methods Realize Fast Computations

  Hajime Igarashi, Yuta Watanabe, Yasuhisa Ito

  IEEE TRANSACTIONS ON MAGNETICS 48 (2) 415 - 418 0018-9464 2012/02 [Refereed][Not invited]
   

  In this paper, deflation method, A-phi method, explicit and implicit error correction (EC) methods and time-periodic explicit error correction (TP-EEC) method are shown to be based on the same mathematical principle that the slowly converging errors are effectively eliminated through the EC process while the fast converging errors are reduced by iterative linear solvers. The properties of the TP-EEC are discussed in detail and the EC is shown to work as an error filter. The numerical experiments show that the error reduction in the time-periodic eddy current problem is in good agreement with those predicted by the present theory.
• Accelerated FDTD Analysis of Antennas Loaded by Electric Circuits

  Yuta Watanabe, Hajime Igarashi

  IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION 60 (2) 958 - 963 0018-926X 2012/02 [Refereed][Not invited]
   

  A fast FDTD method for the analysis of antennas loaded by nonlinear electric circuits is introduced. In the present analysis, the modified nodal analysis (MNA) method is coupled with the FDTD method. The time-periodic explicit error correction (TP-EEC) method is applied to the MNA method for accelerated computation of the transient processes. The present method is applied to analysis of simplified models of an RFID tag composed of a nonlinear electric circuit and line antenna. It is shown that the present method can effectively shorten the computational time by accelerating the transient processes.
• Non-conforming finite element method with tetrahedral elements

  Yasuhisa Ito, Hajime Igarashi, Kota Watanabe, Yosuke Iijima, Kenji Kawano

  INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS 39 (1-4) 739 - 745 1383-5416 2012 [Refereed][Not invited]
   

  This paper presents a non-conforming finite element (FE) method with tetrahedral elements, which is applied to 3-D shape optimization. In the present method, continuity of magnetic flux is directly enforced on the interfaces of different domains in which FE meshes are independently generated. The slave unknowns in one side which are linearly dependent on the unknowns in the other side are eliminated. It is shown that the present method yields accurate solutions to 3-D nonlinear magnetostatic problems. Moreover, evolutional shape optimization of an inductor is shown to be successfully carried out using the present method.
• Double antennas for passive long range UHF-band RFID

  Kota Watanabe, Yuta Watanabe, Hajime Igarashi, Hiroshi Waki

  INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS 39 (1-4) 671 - 676 1383-5416 2012 [Refereed][Not invited]
   

  This paper proposes double antennas which consist of receiver and backscatter antennas for passive long range UHF-band IC (Integrated Circuit) tags. The passive IC tags reply to reader's queries by using backscatter modulation. For this purpose, variable impedance elements are inserted between the antenna and a voltage multiplier which generate dc power. This decreases the efficiency of received power in the voltage multiplier and reduces the communication range. To solve this problem, we propose to use an independent antenna for backscatter modulation. Experimental results and numerical simulation results show that the double antennas successfully reply data from IC tag to the reader.
• Pareto optimization of antennas for passive UHF-band RFID

  Yuta Watanabe, Kota Watanabe, Hajime Igarashi

  INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS 39 (1-4) 747 - 752 1383-5416 2012 [Refereed][Not invited]
   

  This paper presents multi-objective optimization of meander line antennas (MLA) for passive UHF-band Radio Frequency Identification. The characteristics of the MLA loaded by Cockcroft-Walton (CW) circuit are analyzed by hybrid analysis of the finite difference time domain method and modified nodal analysis. The antenna shape is optimized in order to maximize the output voltage of the CW circuit and minimize the antenna size.
• Three dimensional optimization using voxel-based finite element method with homogenization

  Takahiro Sato, Kota Watanabe, Hajime Igarashi, Yosuke Iijima, Kenji Kawano

  INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS 39 (1-4) 761 - 768 1383-5416 2012 [Refereed][Not invited]
   

  In parameter optimization using the finite element method (FEM), re-meshing with long computational time must be performed many times. Although voxel-based FEM is one of the effective techniques to avoid the re-meshing, it has less accuracy in comparison with the conventional FEM because of stair-shaped boundaries. In this work, to improve the computational accuracy in the voxel-based FEM, a new homogenization method is presented. In the present method, the effective reluctivity of finite elements at material interfaces is determined on the basis of magnetic circuit. The present method is successfully applied to three dimensional shape optimization of an inductor model.
• A rationally oriented forgettable profit sharing

  Sadamori Koujaku, Kota Watanabe, Hajime Igarashi

  IEEJ Transactions on Electronics, Information and Systems 電気学会 132 (3) 15 - 454 1348-8155 2012 [Refereed][Not invited]
   

  In this paper, Rationally oriented Forgettable Profit Sharing method (RFPS) for reinforcement learning is proposed. Although the Profit Sharing (PS) provides good performances in real environments, its learning is often slow in long term tasks because it is difficult to determine the adequate discount rate which satisfies the Miyazaki rational theorem. There are several rationality-relaxed PS methods which work well for such tasks. However, these PS may result in many irrational loops. The proposed method fulfills the rationality by forgetting the reinforced irrational loops. This method can be easily combined with ordinary PS methods and performs well in long term tasks. The simulation results show that the proposed method can learn more efficiently than the conventional PS methods. © 2012 The Institute of Electrical Engineers of Japan.
• Monitoring system of railway using passive RFID in UHF band

  Hidetoshi Makimura, Kota Watanabe, Hajime Igarashi, Hiroshi Waki

  IEEJ Transactions on Electronics, Information and Systems 電気学会 132 (5) 691 - 696 1348-8155 2012 [Refereed][Not invited]
   

  This paper presents a novel temperature measurement system based on passive RFID operating at UHF band for monitoring system of conventional railways. The goal of this study is to realize wireless temperature measurement using UHF-band RFID whose communication distance is several meters under the assumption that the RFID reader/writer (R/W) has 4 W EIRP. A low power temperature measurement circuit, which is vital for the above purpose, has been developed using a thermistor and comparator. The temperature measured by this sensor, ranging from zero to 80 Celsius, is shown to be in good agreement with theoretical value. The consumption power of this circuit is evaluated to be 8 ìW by experiment. The sensor circuit is connected to an IC tag, which composed of a meander line antenna, whose shape has been optimized by genetic algorithm, Cockcroft-Walton circuit for booster and rectifier, and PIC for digital control. It is shown that the present wireless sensing system works well when distance between the IC tag and R/W, whose gain is 13 dBi, is set to 1 m and input power to R/W is 1 mW. From this result, the communication distance for 4 W EIRP is roughly estimated to be more than 10 m when neglecting polarization losses and other negative effects. © 2012 The Institute of Electrical Engineers of Japan.
• Medium Affect Reduction for UHF-band passive RFID(19th MAGDA Conference)

  Watanabe Yuta, Makimura Hidetoshi, Watanabe Kota, Igarashi Hajime

  Journal of the Japan Society of Applied Electromagnetics 日本AEM学会 19 (2) 286 - 291 0919-4452 2011/06 [Refereed][Not invited]
   

  This paper presents the influence of scattering objects such as dielectric and metallic plate upon UHF-band passive RFID, and the reduction of affect due to scattering objects. In this work, the IC tags are analyzed by FDTD method and hybridization of FDTD and MNA method. To overcome influence of scattering objects, the dielectric cover and layer having known dielectric permittivity are used for IC tags. It is shown that the presence technique successfully reduces the influence of scattering objects.
• Acquisition of walking behavior for robots using Central Pattern Generator and machine learning methods(19th MAGDA Conference)

  SATO Takahiro, WATANABE Kota, IGARASHI Hajime

  Journal of the Japan Society of Applied Electromagnetics 日本AEM学会 19 (2) 201 - 206 0919-4452 2011/06 [Refereed][Not invited]
   

  Biologically inspired approaches have received much attention for controlling behaviors of robots. In such methods, Central Pattern Generator (CPG) is one of the useful methods for controlling rhythmic behaviors of robots. However, this method has a problem that there are few theories to design CPG. In order to overcome this problem, we propose a combination method of Reinforcement Learning and Genetic Algorithm to obtain suitable parameters in CPG. Furthermore, we show that robots can acquire walking behavior thanks to the method.
• Optimization of Meander Line Antenna Considering Coupling Between Nonlinear Circuit and Electromagnetic Waves for UHF-Band RFID

  Yuta Watanabe, Kota Watanabe, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 47 (5) 1506 - 1509 0018-9464 2011/05 [Refereed][Not invited]
   

  This paper presents optimization of meander line antennas (MLA) for passive IC tags which contain nonlinear circuits. In the present analysis, the tag antenna loaded by the Cockcroft-Walton circuit is analyzed by solving coupling equations for electromagnetic waves and nonlinear circuit with FDTD method. The antenna shape is optimized so that the output voltage of the Cockcroft-Walton circuit is maximized using the micro genetic algorithm (mu GA). The computational burden in the optimization processes is effectively suppressed by truncating the transient computations. A criterion is introduced to evaluate the errors caused by the truncation. The present method yields the optimal MLA which has the greater output voltage in comparison with the dipole antenna.
• Evolutional Design of Small Antennas for Passive UHF-Band RFID

  Hidetoshi Makimura, Yuta Watanabe, Kota Watanabe, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 47 (5) 1510 - 1513 0018-9464 2011/05 [Refereed][Not invited]
   

  This paper presents evolutional design of antennas for UHF-band passive IC tags. The wire-antenna shapes are optimized using the genetic algorithm (GA) aiming at maximization of feeding power to the IC tag as well as minimization of the antenna size. The characteristics of the antennas printed on a dielectric substrate are evaluated using the moment method in the optimization processes. The genotypes for GA are introduced to express the shapes of lattice antennas, which include loops and floating lines, and spiral antennas. The present genotypes for the latter are also valid for optimization of spiral structure of, for example, inductors and filters. It is shown that optimized lattice and spiral antennas have smaller sizes in comparison with the conventional meander antennas.
• Deflation Techniques for Computational Electromagnetism: Theoretical Considerations

  Hajime Igarashi, Kota Watanabe

  IEEE TRANSACTIONS ON MAGNETICS 47 (5) 1438 - 1441 0018-9464 2011/05 [Refereed][Not invited]
   

  This paper describes deflation of finite element (FE) matrices for electromagnetic fields. The condition of the FE matrices is improved by the matrix deflation which replaces small eigenvalues with zeros. It is known that convergence of linear solvers for FE equations can be improved by using the AV method as well as explicit and implicit error correction (EC) methods which have been derived from the multigrid method. These numerical results are theorized on the basis of the matrix deflation. In particular, augmented matrices appeared in the AV and implicit EC methods are shown to have good conditioning after preconditioning. These results suggest that the above methods are based on a common mathematical principle.
• Multigrid Method With Adaptive IDR-Based Jacobi Smoother

  Kota Watanabe, Seiji Fujino, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 47 (5) 1210 - 1213 0018-9464 2011/05 [Refereed][Not invited]
   

  Multigrid (MG) methods are known to be fast linear solvers for large-scale finite-element analyses. The Gauss-Seidel method is usually adopted as the smoother for MG methods. However, recently, considerable attention has focused on induced dimension reduction (IDR)-based solvers because they are faster. In this paper, we investigate the convergence of IDR-based solvers and evaluate the performance of an MG method with an adaptive IDR-based Jacobi smoother. Numerical results show that this method has good convergence and good efficiency in parallel computations for finite-element analysis of electromagnetic fields.
• Optimization of Meander Line Antenna Considering Coupling Between Nonlinear Circuit and Electromagnetic Waves for UHF-Band RFID

  Yuta Watanabe, Kota Watanabe, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 47 (5) 1506 - 1509 0018-9464 2011/05 [Not refereed][Not invited]
   

  This paper presents optimization of meander line antennas (MLA) for passive IC tags which contain nonlinear circuits. In the present analysis, the tag antenna loaded by the Cockcroft-Walton circuit is analyzed by solving coupling equations for electromagnetic waves and nonlinear circuit with FDTD method. The antenna shape is optimized so that the output voltage of the Cockcroft-Walton circuit is maximized using the micro genetic algorithm (mu GA). The computational burden in the optimization processes is effectively suppressed by truncating the transient computations. A criterion is introduced to evaluate the errors caused by the truncation. The present method yields the optimal MLA which has the greater output voltage in comparison with the dipole antenna.
• FDTD法による導波管スロットアレーアンテナに装荷した 球形誘電体レンズの効果の解析

  日本AEM学会誌 19 (2) 378 - 383 2011 [Refereed][Not invited]
  
• 電波型パッシブRFIDのための媒質効果の低減

  日本AEM学会誌 19 (2) 286 - 291 2011 [Refereed][Not invited]
  
• 中枢パターン生成器と機械学習によるロボットの運動自動獲得

  日本AEM学会誌 19 (2) 201 - 206 2011 [Not refereed][Not invited]
  
• Optimization of Inductors Using Evolutionary Algorithms and Its Experimental Validation

  Kota Watanabe, Felipe Campelo, Yosuke Iijima, Kenji Kawano, Tetsuji Matsuo, Takeshi Mifune, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 46 (8) 3393 - 3396 0018-9464 2010/08 [Refereed][Not invited]
   

  This paper presents parameter and topology optimization of inductor shapes using evolutionary algorithms. The goal of the optimization is to reduce the size of inductors satisfying the specifications on inductance values under weak and strong bias-current conditions. The inductance values are computed from the finite-element (FE) method taking magnetic saturation into account. The result of the parameter optimization, which leads to significant reduction in the volume, is realized for test, and the dependence of inductance on bias currents is experimentally measured, which is shown to agree well with the computed values. Moreover, novel methods are introduced for topology optimization to obtain inductor shapes with homogeneous ferrite cores suitable for mass production.
• Complex Adjoint Variable Method for Finite-Element Analysis of Eddy Current Problems

  Hajime Igarashi, Kota Watanabe

  IEEE TRANSACTIONS ON MAGNETICS 46 (8) 2739 - 2742 0018-9464 2010/08 [Refereed][Not invited]
   

  This paper presents the adjoint variable method (AVM) for finite-element (FE) analysis of eddy current problems based on complex variables. In the sensitivity analysis based on FE analysis of time-harmonic eddy current fields, the functions for which sensitivity is evaluated are often real-valued, while unknown variables in the FE analysis are complex. When the AVM is applied to such problems, the real-valued functions are differentiated with respect to the complex variables. However, such differentiation cannot be defined because the Cauchy-Riemann equation does not hold. In this paper, the AVM for complex systems is introduced and applied to linear and nonlinear eddy current problems, in the latter of which the harmonic balance method is employed.
• Robust optimization for electromagnetic systems under uncertainty

  丸山 尚之, 渡邊 浩太, 五十嵐 一

  Journal of the Japan Society for Simulation Technology 日鉄技術情報センタ- 29 (1) 9 - 16 0285-9947 2010/03 [Refereed][Not invited]
  
• A robust optimization based on adjoint variable method

  Takayuki Maruyama, Kota Watanabe, Hajime Igarashi

  COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING 29 (6) 1524 - 1532 0332-1649 2010 [Refereed][Not invited]
   

  Purpose - The purpose of this paper is to present a new method to obtain robust solutions to electromagnetic optimization problems, solved with evolutional algorithms, which are insensitive to changes in design parameters such as spatial size, positioning and material constant. Design/methodology/approach - Adjoint variable method is employed to evaluate the sensitivity of individuals in evolutional processes. Findings - It is shown in the numerical examples, where the present method is applied to optimization of a superconducting energy storage system and C-shape magnet, that robust solutions are actually obtained which are insensitive to deviations in spatial sizes. Originality/value - Unlike usual optimization methods, the present method takes into account deviation in the design parameters due to production errors and long-term changes. Moreover, the present method is limited to about twice the computational cost of non-robust optimization methods.
• Robustness of Nested Multigrid Method for Edge-Based Finite Element Analysis

  Kota Watanabe, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 45 (3) 1088 - 1091 0018-9464 2009/03 [Refereed][Not invited]
   

  The multigrid method is known as. the faster linear solver for large scale finite element analysis. In the edge-based finite element analysis, the geometric multigrid (GMG) method requires careful treatment for the stable convergence. In this paper we investigate factors for stable convergence of nested GMG method. The Numerical results show that the unsuitable application of essential boundary condition to the system matrix results in poor convergence of GMG method. We indicate that the appropriate boundary condition for the system or restriction matrix enable the stable convergence.
• Hybrid Estimation of Distribution Algorithm Using Local Function Approximations

  Felipe Campelo, Frederico G. Guimaraes, Jaime A. Ramirez, Hajime Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 45 (3) 1558 - 1561 0018-9464 2009/03 [Refereed][Not invited]
   

  In this paper, we introduce an approach for the design of electromagnetic devices based on the use of Estimation of Distribution Algorithms (EDAs), coupled with approximation-based local search around the most promising solutions. The-main idea is to combine the power of EDAs in the solution of hard optimization problems with the faster convergence provided by the local search using local approximations. The resulting hybrid, algorithm is tested on a numerical benchmark problem.
• 球形誘電体レンズ装荷による導波管スロットアンテナの放射特性改善

  電子情報通信学会論文誌 J92-B (7) 1185 - 1192 2009 [Refereed][Not invited]
  
• Optimization in Electromagnetics Using the Real-coded Clonal Selection Algorithm

  Felipe Campelo, Frederico G. Guimaraes, Jaime A. Ramirez, Hajime Igarashi

  2008 IEEE CONFERENCE ON SOFT COMPUTING IN INDUSTRIAL APPLICATIONS SMCIA/08 89 - + 2009 [Refereed][Not invited]
   

  This work analyzes the Real-coded Clonal Selection Algorithm (RCSA) for mono objective optimization in electromagnetics. This algorithm presents a set of features enabling global search as well as the local improvement of the candidate solutions. An analysis of the sensitivity of the algorithm to its basic parameters shows that it is possible to suggest a basic configuration for the RCSA, narrowing the range of variation of the input parameters and simplifying the use of the algorithm. Results obtained on a test problem show that this algorithm is able to find higher-quality solutions, and also presents faster convergence than similar approaches for the problem considered.
• Design of mixed H-2/H infinity control systems using algorithms inspired by the immune system

  Frederico G. Guimaraes, Reinaldo M. Palhares, Felipe Campelo, Hajime Igarashi

  INFORMATION SCIENCES 177 (20) 4368 - 4386 0020-0255 2007/10 [Refereed][Not invited]
   

  We utilize optimization algorithms inspired by the immune system for treating the mixed H-2/H-infinity control problem. Both precisely known systems and uncertain systems with polytopic uncertainties are investigated. For the latter, a novel methodology is proposed to compute the worst case norms within the polytope of matrices. This methodology consists in defining the worst case norm computation as an implicit optimization problem with a special structure. We exploit this structure of the problem for its solution. The paper presents both mono and multiobjective optimization algorithms developed from the clonal selection principle. The former is the real-coded clonal selection algorithm (RCSA) and the latter is the multiobjective clonal selection algorithm (MOCSA). The complete design process involves the combination of synthesis and analysis. The RCSA is used for analysis, through the worst case norm computation for a given provided controller. The MOCSA is used for synthesis, working on a population of candidate coritrollers, until providing an estimate of the Pareto set for the mixed d H-2/H-infinity control problem. The numerical examples illustrate the power and the validity of the proposed approach for robust control design. Moreover, our approach for worst case norm evaluation is compared with other approaches available in literature. (c) 2007 ElsevierInc. All rights reserved.
• An analysis of shielding against DC magnetic fields generated by electric railways. Evaluation of effective permeability of fine structure

  Hiroshi Waki, Hajime Igarashi, Toshihisa Honma

  ELECTRICAL ENGINEERING IN JAPAN 160 (4) 7 - 15 0424-7760 2007/09 [Refereed][Not invited]
   

  This paper describes an effective analysis of magnetic shielding based on homogenization. The analyses become time-consuming if the problems include the magnetic substances having fine structure. The homogenization of the structure makes it possible to analyze effectively the magnetic fields. The authors introduce a method to estimate the effective permeability of the homogenized substance. This method can be applied to any periodic structure made of magnetic substance. The magnetic shielding effects by the structures against direct-current (DC) fields generated by electric railways are analyzed by using the present method. As a result, it is found that the overhead way and the protective fence near the railway work as a magnetic shield, whose effects can be improved by appropriate arrangement of those constructions. (C) 2007 Wiley Periodicals, Inc.
• Asymmetrical normal zone propagation analysis considering Hall effect for large aluminum stabilized superconductor

  So Noguchi, Nobuki Kawawada, Hajime Igarashi, Atsushi Ishiyama, Nagato Yanagi, Shinsaku Imagawa

  IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 17 (2) 2490 - 2493 1051-8223 2007/06 [Refereed][Not invited]
   

  Aluminum stabilized superconductors are used in accelerators, SMES, and fusion devices, such as the LHD helical coils. These superconductors have large cross-sectional area of high purity aluminum to improve their stability. However, one of the important properties of these superconductors is the transient stability, which is caused by a long duration of transport current transfer from the superconducting strands into the aluminum in a normal state region. Once a normal zone is initiated in such superconductors, excess joule heat is generated in a small region of the aluminum stabilizer near the superconducting strands during the transport current diffusion time. It hence deteriorates the transient stability. Therefore, it is important to investigate the characteristics of the transient stability by numerical analysis. The latest experiments of the LHD helical coil conductor showed an asymmetrical propagation of normal zone along the longitudinal direction of the conductor. The Hall effect is clearly one of the causes of this phenomenon. The Hall effect prevents the transport current from transferring between the superconducting strands and the aluminum stabilizer. It causes the asymmetrical transport current distribution, and affects the stability of the superconductor. In order to simulate the normal zone propagation in the superconductor more precisely and to clarify the cause of the asymmetrical propagation, we have developed a 2D finite element analysis code taking account of the Hall effect and investigated the characteristics of the normal zone propagation of large aluminum stabilized superconductors.
• Operating property analysis of parallelized resistive fault current limiter using YBCO thin films

  So Noguchi, Takanori Tanikawa, Hajime Igarashi

  IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 17 (2) 1835 - 1838 1051-8223 2007/06 [Refereed][Not invited]
   

  The resistive Superconducting Fault Current Limiters are very attractive devices for electric power circuits. We have investigated the operating properties of a parallelized superconducting fault current limiter made from YBCO thin film and gold film on sapphire substrate by numerical simulation. In order to improve the operating properties and the stability, the YBCO films need to be parallelized. However, it is necessary to investigate whether a few sheets of YBCO film with different critical current density will deteriorate the device's operating properties and stability. That is, when the fault current occurs in power circuit, all YBCO films with different critical current density have not simultaneously quenched. It causes the deterioration of the operating properties. Therefore, it is necessary to investigate the influence of the imbalanced critical current density on the quench characteristics of the parallelized superconducting fault current limiter by numerical simulation. The simulation is performed by a newly developed code coupling the thermal diffusion and the current circuit. It takes into account the E-J power low depending temperature, obtained by experiments. The current limiting properties and the recovery properties are evaluated from quench behavior when the YBCO films have some inhomogeneities. Moreover, the influence of the thickness of gold film on the current limiting properties is also investigated. To grasp such properties is required when the resistive fault current limiter using YBCO thin film is designed.
• Topology optimization based on immune algorithm and multigrid method

  Kota Watanabe, F. Campelo, H. Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 43 (4) 1637 - 1640 0018-9464 2007/04 [Refereed][Not invited]
   

  This paper describes topology optimization of electromagnetic systems using the multigrid method. The topology optimization employs uniform rectangular finite elements, in which the multigrid method works effectively as a fast linear solver. Moreover, the present method uses a new optimization algorithm, based on the artificial immune systems paradigm, in which the multilevel search is carried out.
• Optimization of cost functions using evolutionary algorithms with local learning and local search

  Frederico G. Guimaraes, Felipe Campelo, Hajime Igarashi, David A. Lowther, Jaime A. Ramirez

  IEEE TRANSACTIONS ON MAGNETICS 43 (4) 1641 - 1644 0018-9464 2007/04 [Refereed][Not invited]
   

  Evolutionary algorithms can benefit from their association with local search operators, giving rise to hybrid or memetic algorithms. The cost of the local search may be prohibitive, particularly when dealing with computationally expensive functions. We propose the use of local approximations in the local search phase of memetic algorithms for optimization of cost functions. These local approximations are generated using only information already collected by the algorithm during the evolutionary process, requiring no additional evaluations. The local search improves some individuals of the population, hence speeding up the overall optimization process. We investigate the design of a loudspeaker magnet with seven variables. The results show the improvement achieved by the proposed combination of local learning and search within evolutionary algorithms.
• An automatic hexahedral mesh generation to control shape of elements

  Hirotomo Fujimori, So Noguchi, Hajime Igarashi, Hideo Yamashita

  IEEE TRANSACTIONS ON MAGNETICS 43 (4) 1505 - 1508 0018-9464 2007/04 [Refereed][Not invited]
   

  In this paper, an automatic hexahedral mesh generation method is presented in order to control the element size along each direction. By utilizing Ellipsoidal Bubbles as mesh density data, the present method can generate the mesh with flat elements for analysis, including very thin domain such as eddy current regions of conductor, motor air gaps, and so on. In order to verify the effectiveness of the present method, the finite element analysis was actually performed.
• An Adaptive Mesh Generation With Parameterized Learning

  FUJIMORI Hirotomo, NOGUCHI So, IGARASHI Hajime

  IEEJ Transactions on Industry Applications 電気学会 127 (3) 293 - 299 0913-6339 2007/03 [Refereed][Not invited]
   

  This paper presents an adaptive mesh generation with parameterized learning. The present method does not need to perform iterative processes of field analysis in contrast with the conventional adaptive meshing methods. The present method evaluates mesh qualities for each element by means of evaluation function, which is weighted linear combination of shape and area of elements, distance from material corners and so on. The element which has the worst value of the evaluation function is divided into a few elements according to its shape, and this procedure is repeated until the prescribed nu...
• 六面体辺有限要素解析結果からの磁束線算出手法

  電気学会論文誌B 127 (11) 1205  2007 [Refereed][Not invited]
  
• Analysis of Planar and Curved Microstrip Antennas

  Jacobs R. T.

  Journal of Microwave and Optoelectronics 6 (1) 96 - 110 2007 [Refereed][Not invited]
  
• 3D topology optimization using an immune algorithm

  Felipe Campelo, Kota Watanabe, Hajime Igarashi

  COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING 26 (3) 677 - 688 0332-1649 2007 [Refereed][Not invited]
   

  Purpose - The paper introduces an evolutionary algorithm based on the artificial immune systems paradigm for topology optimization (TO) in 3D. Design/methodology/approach - The 3D TO algorithm is described, and experimentally validated on an electromagnetic design problem. Findings - The proposed method is capable of finding an optimal configuration for the validation problem used. Research limitations/implications - More tests are needed in order to fully assert the capabilities of the algorithm. Moreover, further improvements are needed in order to obtain smoother topologies at the end of the optimization procedure. Practical implications - The paper presents a novel tool for the design of electromagnetic devices, using a TO approach. Originality/value - So far most of the TO algorithms did not tackle true 3D problems, and the ones capable of 3D optimization do it at high computational costs. The algorithm presented here is capable of true 3D design at a reasonable computational budget.
• An efficient parallel PCG method for eddy current analysis

  Kota Watanabe, Hajime Igarashi

  COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING 26 (3) 888 - 898 0332-1649 2007 [Refereed][Not invited]
   

  Purpose - It is important to investigate large-scale numerical analyses of electromagnetic fields in design processes of electromagnetic machines. Thus, faster solvers for eddy current analyses are necessary. Parallel computation methods for linear solvers in electromagnetic field analyses have been investigated. These methods have gained importance due to the diffusion of PC clusters and multi-core CPUs in recent years. Design/methodology/approach - This paper discuses linear solvers for the finite element method in eddy current analyses on parallel computers. The preconditioned conjugate gradient method with overlapping domain decomposition is treated. Some techniques treated to improve the convergence was investigated. Findings - The numerical results show that the overlapping effect results in good convergence in eddy current analyses. Originality/value - The preconditioned conjugate gradient method with overlapping domain decomposition has been treated. The numerical results show that the overlapping method works more efficiently for eddy current analyses. Moreover, this method enables large-scale analyses on popular computers such as PC clusters.
• An Adaptive Mesh Generation With Parameterized Learning

  FUJIMORI Hirotomo, NOGUCHI So, IGARASHI Hajime

  IEEJ Transactions on Industry Applications 一般社団法人 電気学会 127 (3) 293 - 299 0913-6339 2007 [Refereed][Not invited]
   

  This paper presents an adaptive mesh generation with parameterized learning. The present method does not need to perform iterative processes of field analysis in contrast with the conventional adaptive meshing methods. The present method evaluates mesh qualities for each element by means of evaluation function, which is weighted linear combination of shape and area of elements, distance from material corners and so on. The element which has the worst value of the evaluation function is divided into a few elements according to its shape, and this procedure is repeated until the prescribed number of elements is obtained. By using the simple Genetic Algorithm (sGA), the weighting coefficients are optimized through learning with example models such that the resultant mesh has the lowest numerical error.
  The good mesh can be obtained without time-consuming computation, since the weight values for the mesh features are learned by the sGA. The present method would allow us to realize effective design and development of electromagnetic machine and devices.
• Clustering for Semiconductor Defect Using a Small Number of Training Data and Qualitative Knowledge

  Shimomura Shohei, Igarashi Hajime, Hiroi Takashi, Hosoya Naoki, Nakagawa Yasuo

  IEEJ Transactions on Electronics, Information and Systems 一般社団法人 電気学会 127 (6) 914 - 921 0385-4221 2007 [Refereed][Not invited]
   

  In semiconductor wafer manufacturing processes, defect candidates are usually extracted by an inspection system. The defect candidates are composed of true defects such as open circuits, contaminants, and bridge as well as non-defect patterns, called nuisances, which dominate true defects. The goal of this study is to classify the defects candidates into each true defect and nuisance using a small number of training data given by SEM inspection. It is shown that the accuracy of the clustering is considerably improved by introducing qualitative knowledge, which is a priori given by an inspector, in the clustering processes.
• Overview of artificial immune systems for multi-objective optimization

  Felipe Campelo, Frederico G. Guimaraes, Hajime Igarashi

  EVOLUTIONARY MULTI-CRITERION OPTIMIZATION, PROCEEDINGS 4403 937 - + 0302-9743 2007 [Refereed][Not invited]
   

  Evolutionary algorithms have become a very popular approach for multiobjective optimization in many fields of engineering. Due to the outstanding performance of such techniques, new approaches are constantly been developed and tested to improve convergence, tackle new problems, and reduce computational cost. Recently, a new class of algorithms, based on ideas from the immune system, have begun to emerge as problem solvers in the evolutionary multiobjective optimization field. Although all these immune algorithms present unique, individual characteristics, there are some trends and common characteristics that, if explored, can lead to a better understanding of the mechanisms governing the behavior of these techniques. In this paper we propose a common framework for the description and analysis of multiobjective immune algorithms.
• Transient stability analysis taking into account Hall effect for large aluminum stabilized superconductor

  Nobuki Kawawada, So Noguchi, Hajime Igarashi, Atsushi Ishiyama, Nagato Yanagi, Shinsaku Imagawa

  IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 16 (2) 1717 - 1720 1051-8223 2006/06 [Not refereed][Not invited]
   

  Aluminum stabilized superconductors are used in accelerators, SMES, and fusion devices, such as the LHD helical coils. These superconductors have large-cross sectional area of high purity aluminum to improve their stability. However, one of the important properties of these superconductors is the transient stability, which is caused by a long duration of transport current transfer from the superconducting strands into the aluminum in a normal-state region. Once a normal zone is initiated in such superconductors, excess joule heat is generated in a small region of the aluminum stabilizer near the superconducting strands during the transport current diffusion time. It hence deteriorates the transient stability. Therefore, it is important to investigate the characteristics of the transient stability by numerical analysis. The latest experiments of the LHD helical coil conductor show an asymmetrical propagation of normal zone along the longitudinal direction of the conductor. The Hall current generation is clearly one of the causes of this phenomenon. The Hall current generation prevents the transport current from transferring between the superconducting strands and the aluminum stabilizer. It causes the asymmetrical transport current distribution, and affects the stability of the superconductor. In order to simulate the normal-zone propagation in the superconductor more preciously and to clarify the cause of the asymmetrical propagation, we have developed a 2D finite element analysis code taking account of the Hall effect and investigated the transient stability of large aluminum stabilized superconductors.
• A new method for the robust design of high field, highly homogenous superconducting magnets using an immune algorithm

  Felipe Campelo, So Noguchi, Hajime Igarashi

  IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY 16 (2) 1316 - 1319 1051-8223 2006/06 [Not refereed][Not invited]
   

  When designing high-field superconducting magnets, such as the ones used in nuclear magnetic resonance, one is often interested in using the minimum winding volume, in order to reduce the construction costs. On the other hand, a highly homogeneous, highly regulated magnetic field is an essential requirement for this kind of system. Moreover, small variations in the design parameters are unavoidable in the construction of any equipment, and must be taken into account during the design process. Due to these many requirements, the design of magnets with high field homogencity is a very difficult task for traditional optimization methods. Optimization methods based in the artificial immune systems paradigm are usually able to perform global as well as local exploration of the search space. The local search feature can be used to perform an estimation of the sensitivity of the candidate solutions, thus enabling the algorithm to search for points that represent robust devices at a reasonable computational cost. In this work, we explore the design of a high-field, highly homogeneous superconducting magnets by using an immune-based robust optimization algorithm. The algorithm is described, and applied to the optimization of the device. The analysis of the results shows the validity of the proposed method.
• A multiobjective proposal for the TEAM benchmark problem 22

  FG Guimaraes, F Campelo, RR Saldanha, H Igarashi, RHC Takahashi, JA Ramirez

  IEEE TRANSACTIONS ON MAGNETICS 42 (4) 1471 - 1474 0018-9464 2006/04 [Not refereed][Not invited]
   

  The TEAM benchmark problem 22 is an important optimization problem in electromagnetic design, which can be formulated as a constrained mono-objective problem or a multiobjective one with two objectives. In this paper, we propose a multiobjective version with three objectives, whose third objective is related to the quench constraint and the better use of the superconducting material. The formulation proposed yields results that provide new alternatives to the designer. We solved the formulation proposed using the multiobjective clonal selection algorithm. After that, we selected a particular solution using a simple decision making procedure.
• A modified immune network algorithm for multimodal electromagnetic problems

  F Campelo, FG Guimaraes, H Igarashi, JA Ramirez, S Noguchi

  IEEE TRANSACTIONS ON MAGNETICS 42 (4) 1111 - 1114 0018-9464 2006/04 [Not refereed][Not invited]
   

  Some optimization algorithms based on theories from immunology have the feature of finding an arbitrary number of optima, including the global solution. However, this advantage comes at the cost of a large number of objective function evaluations, in most cases, prohibitive in electromagnetic design. This paper proposes a modified version of the artificial immune network algorithm (opt-AINet) for electromagnetic design optimization. The objective of this modified AINet (m-AINet) is to reduce the computational effort required by the algorithm, while keeping or improving the convergence characteristics. Another improvement proposed is to make it more suitable for constrained problems through the utilization of a specific constraint-handling technique. The results obtained over an analytical problem and the design of an electromagnetic device show the applicability of the proposed algorithm.
• A reduced model for finite element analysis of steel laminations

  H Igarashi, K Watanabe, A Kost

  IEEE TRANSACTIONS ON MAGNETICS 42 (4) 739 - 742 0018-9464 2006/04 [Not refereed][Not invited]
   

  This paper describes a method which reduces the number of unknowns in the finite element analysis of steel laminations. In the present method, the global variation in the electromagnetic field is assumed to be piecewise linear or polynomial while periodical, local variation is analyzed by the finite element method. This method allows us to make accurate analysis of the field including edge effects in steel laminations with low memory consumption and short computing time.
• Analysis of magnetic shielding effect of layered shields based on homogenization

  H Waki, H Igarashi, T Honma

  IEEE TRANSACTIONS ON MAGNETICS 42 (4) 847 - 850 0018-9464 2006/04 [Not refereed][Not invited]
   

  This paper describes a nonlinear analysis of magnetic field based on homogenization. The analysis of a magnetic field is time-consuming when the problem includes magnetic substance with fine structure. Simplification of the fine structure by homogenization makes it possible to analyze them efficiently. The authors have introduced a homogenization method to estimate effective permeability of magnetic composite structure for a static field. This method can be applied not only for linear problems but also nonlinear ones. In this paper, the magnetic shielding effect of layered nonlinear material is analyzed by using the homogenization method, and the applicability of this method is discussed.
• Estimation of non-linear effective permeability of magnetic materials with fine structure

  H Waki, H Igarashi, T Honma

  PHYSICA B-CONDENSED MATTER 372 (1-2) 383 - 387 0921-4526 2006/02 [Refereed][Not invited]
   

  This paper describes a homogenization method for magnetic materials with fine structure. In this method, the structures of the magnetic materials are assumed to be periodic, and the unit cell is defined. The effective permeability is determined on the basis of magnetic energy balance in the unit cell. This method can be applied not only for linear problems but also for non-linear ones. In this paper, estimation of the effective permeability of non-linear magnetic materials by using the homogenization method is described in detail, and then the validity for the non-liner problems is tested for two-dimensional problems. It is shown that this homogenization method gives accurate non-linear effective permeability. (c) 2005 Elsevier B.V. All rights reserved.
• Local learning and search in memetic algorithms

  Frederico G. Guimaraes, Elizabeth F. Wanner, Felipe Campelo, Ricardo H. C. Takahashi, Hajime Igarashi, David A. Lowther, Jaime A. Ramirez

  2006 IEEE CONGRESS ON EVOLUTIONARY COMPUTATION, VOLS 1-6 2921 - + 2006 [Not refereed][Not invited]
   

  The use of local search in evolutionary techniques is believed to enhance the performance of the algorithms, giving rise to memetic or hybrid algorithms. However, in many continuous optimization problems the additional cost required by local search may be prohibitive. Thus we propose the local learning of the objective and constraint functions prior to the local search phase of memetic algorithms, based on the samples gathered by the population through the evolutionary process. The local search operator is then applied over this approximated model. We perform some experiments by combining our approach with a real-coded genetic algorithm. The results demonstrate the benefit of the proposed methodology for costly black-box functions.
• F. Campelo, F.G. Guimaraes, H. Igarashi, K. Watanabe, J.A. Ramirez

  Proc. IEEE world congress on computational intelligence 10973  2006 [Not refereed][Not invited]
  
• An immune-based algorithm for topology optimization

  Felipe Campelo, Frederico G. Guimaraes, Hajime Igarashi, Kota Watanabe, Jaime A. Ramirez

  2006 IEEE CONGRESS ON EVOLUTIONARY COMPUTATION, VOLS 1-6 3189 - + 2006 [Refereed][Not invited]
   

  Traditional shape optimization of engineering devices usually starts with an initial user-defined configuration of material. Optimization algorithms are then applied for optimizing objective functions of predefined parameters. While this approach can yield efficient results, it is essentially limited, since limitations in the initial design forbid the computational methods to explore different distributions of material as solutions for a given problem. In other words, the algorithms are not allowed to exhibit creativity in the design process. Topology optimization is a paradigm for optimization that allows such creativity to emerge. Instead of optimizing functions of user-defined parameters, this paradigm optimizes the material properties of each point of the design space, and its methods are theoretically able to describe all possible devices within a limited space. This work presents a new methodology for topology optimization, based on an evolutionary paradigm known as artificial immune systems. The proposed technique is capable of exploring the space locally as well as globally, efficiently searching for the optimal distribution of material. It also incorporates strategies for the evolution of smoother, more regular shapes, in order to generate physically feasible solutions for engineering problems.
• Visualization of optimal solutions using self-organizing maps in computational electromagnetism

  H Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 41 (5) 1816 - 1819 0018-9464 2005/05 [Not refereed][Not invited]
   

  In this paper, the self-organizing map is applied for visualization and clustering of optimal solutions in parameter spaces. The present method is tested for the simplified version of De Jong's function and TEAM workshop problem 22. It is shown that the present method successfully visualizes the distribution of optimal solutions, and allows us to classify the optimal solutions into clusters. Moreover, the optimal regions which include clustered optimal solutions in the parameter space can be obtained by the present method.
• A clonal selection algorithm for optimization in electromagnetic

  F Campelo, FG Guimaraes, H Igarashi, JA Ramirez

  IEEE TRANSACTIONS ON MAGNETICS 41 (5) 1736 - 1739 0018-9464 2005/05 [Not refereed][Not invited]
   

  This paper proposes the real-coded clonal selection algorithm (RCSA) for use in electromagnetic design optimization. Some features of the algorithm, such as the number of clones, mutation range, and the fraction of the population selected each generation are discussed. The TEAM Workshop problem 22 is investigated, in order to illustrate the performance of the algorithm in a real electromagnetic problem. The results obtained, a set of optimal solutions representing a broader range of options for the designer, are compared with those achieved by a genetic algorithm, showing the efficiency of the RCSA in practical optimization problems.
• Comparison of geometric and algebraic multigrid methods in edge-based finite-element analysis

  K Watanabe, H Igarashi, T Honma

  IEEE TRANSACTIONS ON MAGNETICS 41 (5) 1672 - 1675 0018-9464 2005/05 [Not refereed][Not invited]
   

  This paper discusses the comparison between the geometric multigrid (GMG) method and the algebraic multigrid (AMG) method in edge-based finite-element (FE) analysis. The GMG method requires the hierarchical meshes. On the other hand, the AMG method requires the only a single mesh information. The system matrices of the coarse grids are generated using algebraic operation in AMG. The numerical results show that both multigrid methods are faster than the conventional solvers in large-scale analysis. Although multigrid methods require the setup procedures, the calculation time of these procedures is comparatively short and increase linearly with the number of unknowns.
• Estimation of ettective permeability of magnetic composite materials

  H Waki, H Igarashi, T Honma

  IEEE TRANSACTIONS ON MAGNETICS 41 (5) 1520 - 1523 0018-9464 2005/05 [Not refereed][Not invited]
   

  This paper describes a method to estimate effective permeability of magnetic composite materials for static field. In the present method, the structures of the composite materials are assumed to be periodic, and the unit cell is defined. The effective permeability is determined on the basis of magnetic energy balance in the unit cell. The present method considers magnetic interaction between inclusions of the composite materials, and is more accurate and useful. Therefore, the present method can be more widely applied than conventional models, for example, the Maxwell-Garnett formula and the Bruggeman formula. Validity of the present method is confirmed by numerical analyses. This approach can be applied also to nonlinear magnetic composite materials.
• An analysis of magnetic shielding against DC power lines based on homogenization

  H Waki, H Igarashi, T Honma

  COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING 24 (2) 566 - 580 0332-1649 2005 [Not refereed][Not invited]
   

  Purpose - To analyze effectively magnetic shielding effects by shields with fine structure. Design/methodology/approach - Simplification of the fine structure makes it possible to analyze them efficiently. The authors have introduced a homogenization method to estimate effective permeability of magnetic composite structure for the static field. The homogenization method is applied to the analysis of magnetic shields composed of steel plates and steel rods against DC power lines to test its feasibility. Findings - The properties of the magnetic shielding are analyzed by using the homogenization method. The errors of the magnetic fields increase in case of very few layers. Originality/value - The simplification of the magnetic shields with fine structure by using the homogenization method makes it possible to analyze efficiently magnetic shielding effects, although the accuracy becomes worse in case of very few layers.
• On robustness of edge-based FE analysis using algebraic multigrid method

  K Watanabe, H Igarashi

  COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING 24 (2) 408 - 417 0332-1649 2005 [Not refereed][Not invited]
   

  Purpose - This paper discusses the robustness of the algebraic multigrid (AMG) method as well as geometric multigrid (GMG) method against mesh distortion in edge-based finite element analysis. Design/methodology/approach - Analyzes a simple magnetostatic problem, in which the model consists of a cubic iron and the surrounding air region. Prepares three meshes which have same number of elements to evaluate the robustness of multigrid against the distortion of mesh. Findings - The AMG method is shown to be more robust against mesh distortion than the GMG method. Originality/value - Shows that the AMG is more robust than the GMG. This result is of practical interest to the researchers in this field.
• An Analysis of Shielding against DC Magnetic Fields Generated by Electric Railways: Evaluation of Effective Permeability of Fine Structures

  Hiroshi Waki, Hajime Igarashi, Toshihisa Honma

  IEEJ Transactions on Fundamentals and Materials 125 (4) 309 - 316 1347-5533 2005 [Not refereed][Not invited]
   

  This paper describes an effective analysis of magnetic shielding based on homogenization. The analyses become time-consuming if the problems include the magnetic substances having fine structure. The homogenization of the structure makes it possible to analyze effectively the magnetic fields. The authors introduce a method to estimate the effective permeability of the homogenized substance. This method can be applied to any periodic structure made of magnetic substance. The magnetic shielding effects by the structures against direct-current (DC) fields generated by electric railways are analyzed by using the present method. As a result, it is found that the overhead way and the protective fence near the railway work as a magnetic shield, whose effects can be improved by appropriate arrangement of those constructions. © 2005, The Institute of Electrical Engineers of Japan. All rights reserved.
• Robustness of the multigrid method for edge-based finite element analysis

  K Watanabe, H Igarashi, T Honma

  ELECTRICAL ENGINEERING IN JAPAN 148 (1) 75 - 81 0424-7760 2004/07 [Refereed][Not invited]
   

  The dependence of the multigrid finite element method solving three-dimensional magnetostatic fields on the quality of the finite element mesh is reported. It is shown that the convergence of the multigrid method is strongly influenced by the mesh quality. Moreover, the multigrid method with ICCG smoother is shown to be more robust against mesh distortion than that with Gauss-Seidel and SOR smoothers. (C) 2004 Wiley Periodicals, Inc.
• A finite-element analysis of surface wave plasmas

  H Igarashi, K Watanabe, T Ito, T Fukuda, T Honma

  IEEE TRANSACTIONS ON MAGNETICS 40 (2) 605 - 608 0018-9464 2004/03 [Not refereed][Not invited]
   

  This paper describes a finite-element analysis of surface microwaves coupled to a cold nonmagnetized plasma for chemical vapor deposition (CVD). The microwave-plasma coupling is taken into account by introducing the frequency-dependent permittivity. The computed resonant modes of the surface wave on the interface between the dielectric and plasma in a cylindrical vessel are shown to be in good agreement with the theoretical ones. Moreover, the computed field distribution for a waveguide loaded cylindrical vessel agrees well with that computed by the finite-difference time-domain (FDTD) method.
• On Robustness of Multigrid Method for Edge-Based Finite Element Analysis.

  Kota Watanabe, Hajime Igarashi, TosMhisa Honma

  IEEJ Transactions on Industry Applications 123 (3) 257 - 262 1348-8163 2003/09/01 [Not refereed][Not invited]
   

  The dependence of the multigrid-finite element method solving three dimensional magnetostatic fields onthe quality of the finite element mesh is reported. It is shown that the convergence of the muitigrid method is strongly influenced by the mesh quality. Moreover, the muitigrid method with ICCG-smoother is shown to be more robust against mesh distortion than that with Gauss-Seidel and SOR smoothers. © 2003, The Institute of Electrical Engineers of Japan. All rights reserved.
• On Robustness of Multigrid Method for Edge-Based Finite Element Analysis.

  Kota Watanabe, Hajime Igarashi, TosMhisa Honma

  IEEJ Transactions on Industry Applications 電気学会 123 (3) 257 - 262 1348-8163 2003/09/01 [Not refereed][Not invited]
   

  The dependence of the multigrid-finite element method solving three dimensional magnetostatic fields onthe quality of the finite element mesh is reported. It is shown that the convergence of the muitigrid method is strongly influenced by the mesh quality. Moreover, the muitigrid method with ICCG-smoother is shown to be more robust against mesh distortion than that with Gauss-Seidel and SOR smoothers. © 2003, The Institute of Electrical Engineers of Japan. All rights reserved.
• An inverse analysis of permeability distribution in construction (Special Issue on Inverse Problems)

  WAKI Hiroshi, IGARASHI Hajime, HONMA Toshihisa

  Journal of the Japan Society of Applied Electromagnetics 日本AEM学会 11 (2) 82 - 87 0919-4452 2003/06/10 [Not refereed][Not invited]
   

  This paper discusses reconstruction of permeability distribution in constructions. Electronic devises such as cathode ray tubes and electron microscopes are often severely affected by the terrestrial magnetism as well as magnetic fields generated from traffic systems. Those environmental magnetic fields are disturbed by steel frames embedded in constructions, and magnetic fields can thus become highly non-uniform in rooms. It is effective for the design of the magnetic shielding to take the non-uniformity of the magnetic fields into account. However it is often difficult to know the position and magnetic permeability of the steel frames in existing constructions. In this work, the magnetic permeability distribution inside a construction is reconstructed from magnetic fields measured on the construction surface. In particular it is shown that the convergence of the inferred permeability can effectively be accelerated by using a priori knowledge of the permeability.
• Convergence of multigrid method for edge-based finite-element method

  K Watanabe, H Igarashi, T Honma

  IEEE TRANSACTIONS ON MAGNETICS 39 (3) 1674 - 1676 0018-9464 2003/05 [Not refereed][Not invited]
   

  This paper discusses robustness of the multigrid (MG) method against distortion of finite elements. The convergence of MG method becomes considerably worse as the finite elements become flat. It is shown that the smoother used in the MG method cannot effectively eliminate the high-frequency component of the residue for flat elements, and this gives rise to deterioration in the convergence. Moreover, the multigrid method with conjugate gradient (CG) smoother is shown to be more robust against mesh distortion than that with Gauss-Seidel smoother.
• Convergence of preconditioned conjugate gradient method applied to driven microwave problems

  H Igarashi, T Honma

  IEEE TRANSACTIONS ON MAGNETICS 39 (3) 1705 - 1708 0018-9464 2003/05 [Not refereed][Not invited]
   

  Driven microwave problems can be solved with the finite-element method formulated in terms of the electric field, as well as the vector and scalar potentials. It is known that the latter gives faster convergence of the preconditioned conjugate gradient method than the former. This can be understood from the following facts: namely; the preconditioned finite-element matrix of the former method can contain small negative eigenvalues which make the matrix condition worse. On the other hand, in the latter, such eigenvalues are shown to be composed of zeros and normalized ones.
• Convergence of Multigrid Finite Element Method in Eddy Current Analysis

  Kota Watanabe, Hajime Igarashi, Toshihisa Honma

  Annual Review of Progress in Applied Computational Electromagnetics 775 - 778 2003 

  The dependence of the multigrid-finite element method solving three-dimensional quasistatic electromagnetic fields on the frequency of the source current is reported. It is show that the decrease in frequency makes the convergence of multigrid method worse. Moreover, the multigrid method with ICCG-smoother is shown to be more robust against the decrease in frequency than that with Gauss-Seidel smoother.
• "構造物内部の透磁率分布の逆解析"

  日本AEM学会誌 11 82 - 87 2003 [Not refereed][Not invited]
  
• H. Igarashi, K. Ooi and T. Honma, "A Magnetostatic Reconstruction of Permeability Distribution in Material", Inverse Problems in Engineering Mechanics IV, ed. M. Tanaka, 383-388 (Elsevier, Berlin) (2003)*

  2003 [Not refereed][Not invited]
  
• On convergence of ICCG applied to finite-element equation for quasi-static fields

  H Igarashi, T Honma

  IEEE TRANSACTIONS ON MAGNETICS 38 (2) 565 - 568 0018-9464 2002/03 [Not refereed][Not invited]
   

  This paper discusses convergence of the incomplete Cholesky conjugate gradient method (ICCG) which solves edge-based finite-element equations for quasi-static electromagnetic fields. It has been observed in numerical computations that convergence of ICCG for the A-V method is faster than that for the A method. This phenomenon is found to be explained by the fact that, in the A-V method, the preconditioning eliminates the small singular values which deteriorate the condition number while they remain after the preconditioning in the case of the A method.
• Property of Second Order Edge Elements in a Class

  International Journal of Applied Electromagnetics and Mechanics 14 15 - 18 2002 [Not refereed][Not invited]
  
• Igarashi, H. and Honma, T.:"A Direct Reconstruction of Magnetic Charge for Non-Destructive Testing ", Electromagnetic Nondestructive Evaluation IV, (IOS Press)29-34(2002)*

  2002 [Not refereed][Not invited]
  
• Reconstruction of Planar Magnetic Charge Distribution

  International Journal of Applied Electromagnetics and Mechanics 15 257 - 260 2002 [Not refereed][Not invited]
  
• A direct reconstruction of magnetic charge for non-destructive testing

  H Igarashi, T Honma

  ELECTROMAGNETIC NONDESTRUCTIVE EVALUATION (VI) 23 29 - 34 1383-7281 2002 [Refereed][Not invited]
   

  The magnetic charge, which is due to martensite transformation around a crack in ferromagnetic materials, is reconstructed from the magnetic fields measured on a plane above the charge region. It is shown that both Tikhonov method with an appropriate regularization term and iterative regularization based on the CG method solving a modified normal equation yield satisfactory solutions. The regularization parameter for the Tikhonov method can be determined from the L-curve when the noise level is under 10% of measurement data. The residual tolerance of CG iteration, which gives great influence on the solution, can roughly be estimated from the discrepancy principle.
• On the property of the curl-curl matrix in finite element analysis with edge elements

  H Igarashi

  IEEE TRANSACTIONS ON MAGNETICS 37 (5) 3129 - 3132 0018-9464 2001/09 [Not refereed][Not invited]
   

  This paper discusses properties of the curl-curl matrix in the finite element formulation with edge elements. Moreover the observed deceleration in convergence of the CG and ICCG methods applied to magnetostatic problems through the tree-cotree gauging is explained on the basis of the eigenvalue separation property. From the eigenvalue separation property it follows that neither minimum nonzero eigenvalue of the curl-curl matrix nor maximum one Increase through the tree-cotree gauging. Hence it is concluded that the condition number of the curl-curl matrix tends to grow by its definition. Moreover the maximum eigenvalue tends to keep constant whereas the minimum nonzero eigenvalue reduces. This property also makes the condition number worse.
• Properties of second-order edge elements

  Hajime Igarashi, Toshihisa Honma

  International Journal of Applied Electromagnetics and Mechanics 14 (1-4) 15 - 18 1383-5416 2001 

  This paper discusses properties of the second-order edge elements for the finite element analysis. It is shown that the condition number, which dominates the convergence of the ICCG method, can be different even for the equivalent second-order elements which have common basis vectors. Moreover the computed eigenvalues and condition numbers of the local and global stiffness matrices are shown to be consistent with the reported convergence of the ICCG method. It is suggested that the spectrum of the local stiffness matrix is useful for prediction of the ICCG convergence.
• Igarashi, H. and Honma, T., "On Identification of Magnetic Sources in Materials", Inverse Problems in Engineering Mechanics III, eds. M. Tanaka and G.S. Dulikravich, Elsevier, 403-410 (2001)*

  2001 [Not refereed][Not invited]
  
• Inverse inference of magnetization distribution in cylindrical permanent magnets

  H Igarashi, T Honma, A Kost

  IEEE TRANSACTIONS ON MAGNETICS 36 (4) 1168 - 1171 0018-9464 2000/07 [Not refereed][Not invited]
   

  In this paper the magnetization distribution in a cylindrical permanent magnet, called magnet roller, used in copy machines and laser printers, is determined from the magnetic fields measured on a circle outside the roller, The system matrix, which is singular because of luck of uniqueness of the solution, is regularized by the Tikhonov method. The determination of the optimal regularization parameter based on the L-curve method is discussed. It is shown that the uniform and distributed magnetization patterns are successfully reconstructed by the present method.
• 円筒形永久磁石の順・逆解析

  電気学会論文誌 A 120巻 (8/9号) 791 - 797 2000 [Not refereed][Not invited]
  
• Igarashi, H.:"On the Reconstruction of Magnetic Source in Cylindrical Permanent Magnets", Inverse Problems in Engineering Mechanics II, eds. Tanaka, M. and Dulikravich, G.S., Elsevier: 467-476 (2000)*

  2000 [Not refereed][Not invited]
  
• On the parameter identification and application of the Jiles-Atherton hysteresis model for numerical modelling of measured characteristics

  D Lederer, H Igarashi, A Kost, T Honma

  IEEE TRANSACTIONS ON MAGNETICS 35 (3) 1211 - 1214 0018-9464 1999/05 [Refereed][Not invited]
   

  The application of the Jiles-Atherton hysteresis model for numerical modelling of measured magnetic hysteresis characteristics of constructional steel is investigated. Parameter identification is done using the stochastic optimization method "simulated annealing". Modifications of the original model, which were proposed to overcome its drawbacks, are examined, resulting in a new combined Jiles-Atherton and scaling model.
• A time-domain analysis of Schrodinger equation for single electron in magnetic field

  H Igarashi, T Yoshikawa, T Honma

  IEEE TRANSACTIONS ON MAGNETICS 35 (3) 1518 - 1521 0018-9464 1999/05 [Refereed][Not invited]
   

  In this paper the time-dependent Schrodinger equation governing dynamics of single electron in magnetic fields is solved by the finite difference method (FDM) with the explicit central difference scheme and Trotter-Suzuki method (TSM). Motion of a wave packet in rectangular and stadium-shaped domains immersed in uniform magnetic field is analyzed. The performance of the two numerical methods is compared. It is shown that FDM is superior over TSM for accuracy and computing efficiency while TSM is superior for numerical stability. Moreover the probability density of an electron in the stadium is shown to form complex spatial patterns which, suggest quantum chaos.
• Effective reluctivity calculation versus time step calculation of magnetic shielding with ferromagnetic material

  D Lederer, H Igarashi, A Kost, T Honma

  COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING 18 (3) 410 - 421 0332-1649 1999 [Refereed][Not invited]
   

  The calculation of magnetic shielding with ferromagnetic material by an effective reluctivity method and a time step method based on the finite element calculation is investigated The calculation results of both methods are compared with measurement results and with each other in order to check their reliability and accuracy. It turns out that both methods give similar results for the field inside the shielding material, whereas in the surrounding air the effective reluctivity method gives more accurate results than the present time step method.
• A three dimensional analysis of magnetic fields around a thin magnetic conductive layer using vector potential

  H Igarashi, A Kost, T Honma

  IEEE TRANSACTIONS ON MAGNETICS 34 (5) 2539 - 2542 0018-9464 1998/09 [Refereed][Not invited]
   

  This paper describes a method for the three dimensional analysis of quasi-static magnetic fields around a thin magnetic conductive layer, The impedance boundary conditions (IBCs) for the vector potential are introduced on both sides of the layer surface. The magnetic field around the layer is numerically determined under the IBCs. The present method does not require numerical analysis of the electromagnetic field inside the layer which is formidable due to its extreme spatial structure. The present method gives reasonable solutions to numerical examples.
• A numerical investigation of Preisach and Jiles models for magnetic hysteresis

  H Igarashi, D Lederer, A Kost, T Honma, T Nakata

  COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING 17 (1-3) 357 - 363 0332-1649 1998 [Refereed][Not invited]
   

  The Preisach and Jiles models for hysteresis are applied to reconstruct BH loops from measurement data for constructional steel St 37. The distribution function for the Preisach model is determined from all the available, 18, measured BH loops starting from the initial curve. The five unknown parameters in Jiles model are determined by the simulated annealing method to minimize the distance between the largest measured BH loop and the corresponding computed loop. Although Jiles model gives differences from the measured BH loops for low applied fields, it provides results fitted well to the largest measured loop for which the parameters are optimized. The Preisach model gives good fitting over a wide range of the applied field.
• A numerical method for thin structures: An FEM-BEM hybridization for the analysis of ferromagnetic layers

  H Igarashi, D Lederer, T Honma, A Kost

  NON-LINEAR ELECTROMAGNETIC SYSTEMS 13 653 - 656 1383-7281 1998 [Refereed][Not invited]
   

  This paper describes a numerical method for analysis of electromagnetic fields around thin ferromagnetic layers with time-dependent source currents. In this method, the electromagnetic fields inside the thin layer are assumed to obey the one dimensional magnetic-diffusion equation while the field in air around the layer is assumed to be a quasi-static magnetic field in full dimensions. The nonlinearity in the magnetic characteristics of the ferromagnetic material is taken into account. The interior and exterior fields are analyzed by finite and boundary element methods, respectively. The present method gives results similar to experimental results for a shielding thin plate.
• Impedance boundary condition for vector potentials on thin layers and its application to integral equations

  H Igarashi, A Kost, T Honma

  EUROPEAN PHYSICAL JOURNAL-APPLIED PHYSICS 1 (1) 103 - 109 1286-0042 1998/01 [Refereed][Not invited]
   

  Thin layers of magnetic substance are often used in magnetic shieldings. Since the scale of the spatial change in electromagnetic fields in the direction of the thickness of such a thin layer is considerably different from that in the transverse directions, the numerical treatment of the interior electromagnetic fields is formidable. In this paper, it is shown that the impedance boundary conditions on the surfaces of the thin magnetic layer, which have been written in former papers by the scalar potentials, can be expressed in terms of the vector potentials, Moreover, a new numerical method for analysis of eddy currents on thin magnetic layers is introduced, in which the quasi-static magnetic field in an air region ambient the thin layer is analyzed by solving the boundary integral equations under the impedance boundary conditions without any numerical treatment of the interior field, This formulation has no difficulties even when the skin depth is very short compared with the thickness of the layer. It is shown that the numerical results obtained by the present method in two-dimensional and axisymmetric systems agree well with the results analytically obtained or computed by a conventional numerical method.
• A boundary element analysis of magnetic shielding for electron microscopes

  H Igarashi, A Kost, T Honma

  COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING 17 (5-6) 585 - 594 0332-1649 1998 [Refereed][Not invited]
  
• The Newton-Raphson method for complex equation systems

  Dieter Lederer, Hajime Igarashi, Arnulf Kost

  Applied Computational Electromagnetics Society Journal 12 (2) 113 - 116 1054-4887 1997/03 

  A formulation for the complex Newton-Raphson method is proposed. The derivation is obtained on the assumption of a nonanalytical equation system. The method is applied to the finite element calculation of shielding problems with sinusoidal excitation and ferromagnetic material. An application example for which measurement data are available is given in order to judge the convergence characteristics and the reliability of the proposed method.
• A kinetic analysis of plasma sheaths by integral equation method

  K Tsubota, H Igarashi, T Honma

  IEEE TRANSACTIONS ON MAGNETICS 33 (2) 1366 - 1369 0018-9464 1997/03 [Not refereed][Not invited]
   

  We report the analysis of plasma sheaths which occur between plasma and the wall. The plasma equation which governs sheaths[1] has been already solved by Bissell et al[2], but the serious numerical errors occur in their results because the singularity exists in the equation, We consider the singularity and develop the method which regularizes the singularity, so that we confirm the errors are improved, We think this method is available for another calculation of the equation which includes the singularity.
• Kost, A. and Igarashi, H. : "Different Numerical Methods for Electromagnetic Field Calculation with Respect to EMC Problems", Electromagnetic Field Problems and Applications, 276-281 (1997)＊

  1997 [Not refereed][Not invited]
  
• Lederer, D., Igarashi, H. and Kost, A. : "A Newton-Raphson Method for Complex Systems・h, ACES Journal, 12(2) : 113-116 (1997)＊

  1997 [Not refereed][Not invited]
  
• Igarashi, H., Honma, T. and Kost, A. : "A Three-Dimensional Analysis of Magnetic Shielding with Thin Layers", ACES Journal, 12(2) : 71-74 (1997)＊

  1997 [Not refereed][Not invited]
  
• Different numerical methods for electromagnetic field computation with thin shielding sheets

  A Kost, H Igarashi

  IEEE 1997 INTERNATIONAL SYMPOSIUM ON ELECTROMAGNETIC COMPATIBILITY - SYMPOSIUM RECORD 248 - 253 1997 [Refereed][Not invited]
   

  The disturbance of sensitive measurement and control equipment by electromagnetic fields is a central problem in electromagnetic compatibility. A removal or reduction of such a disturbance is achieved by thin shielding sheets, the optimum design of which nowadays can be found by numerical methods. This paper describes the principles of three new methods for this task. The first method is the conventional hybrid FEM/BEM-method, which analyzes a 3D distribution of the fields numerically in the interior of the shielding sheet as well as in its surroundings, In the case of linear shielding material the 3D discretization can be replaced by a 2D one on the shielding sheet surface in the second and third method. While the second method leads to a more appropriate FEM/BEM formulation for thin shielding sheets than the first one, the third one has the advantage that only a BEM formulation is needed to solve the problem. Some EMC applications and their results illustrate the use of the methods.
• Different numerical methods for electromagnetic field calculation with respect to EMC problems

  A Kost, H Igarashi

  ELECTROMAGNETIC FIELD PROBLEMS AND APPLICATIONS (ICEF '96) 276 - 281 1997 [Refereed][Not invited]
   

  This paper describes two different numerical methods for the analysis of electromagnetic fields with respect to EMC problems. The methods can analyze electromagnetic fields, ranging from static to high-frequency fields, with thin shielding materials. In the methods, FEM is employed to solve a couple of differential equations which express the relation between the magnetic fields on both surfaces of the shielding material. The magnetic fields in vacuum regions are modeled by means of BEM. The FEM-BEM coupled equations are solved to evaluate shielding property. The first method described in this paper employs the potentials and the normal components of magnetic fields on the surfaces of the shielding material for unknowns. It is impossible to apply this method to the analysis of shielding materials with open surfaces unless a fictitious boundary is introduced in vacuum region. One the other hand, the second method, which employs the jump in the potential and normal component of the magnetic fields across the thin shielding material as unknown variables, can analyze shielding materials with both open and closed surfaces. The number of unknowns in the latter is half of that in the former. Though both methods give slight discrepancies in the computed shielding factors at high frequencies, the results computed by them are almost identical.
• A boundary element method for potential fields with corner singularities

  H Igarashi, T Honma

  APPLIED MATHEMATICAL MODELLING 20 (11) 847 - 852 0307-904X 1996/11 [Not refereed][Not invited]
   

  It is known that the spatial derivatives of a potential function become infinite at corner points on a boundary under certain conditions. Numerical methods such as finite and boundary element methods cannot adequately analyse the potential fields with those field singularities since they conventionally employ piecewise polynomials. This paper presents a boundary element formulation for the accurate analysis of two-dimensional potential fields with the field singularities. In this method boundary integral equations are formulated for unknown regularised functions, which are introduced by subtracting off the field singularities from the original potential function. Moreover at the singular corner points boundary integral equations are formulated to determine the unknown expansion coefficients that characterize the behavior of the potential function around the singular corner points. By simultaneously solving the boundary integral equations for the regularized function and the expansion coefficients the original potential function is accurately determined. (C) 1996 by Elsevier Science Inc.
• A boundary element analysis of transmission-line parameters using singular elements

  H Igarashi, Y Mizuyama, T Honma

  IEEE TRANSACTIONS ON MAGNETICS 32 (3) 686 - 689 0018-9464 1996/05 [Not refereed][Not invited]
   

  This paper presents a boundary element analysis of transmission-line parameters on the basis of the quasi-TEM assumption. Singular boundary elements are employed to adequately express the corner singularities at sharp conductor edges. The boundary integrals consisting of the Green function and singular interpolation functions are regularized by a Taylor expansion technique, and are then evaluated using the standard Gaussian quadrature, The numerical results for test problems show the reliability of the present method.
• An analysis of thin magnetic materials using hypersingular integral equations

  H Igarashi, T Honma

  IEEE TRANSACTIONS ON MAGNETICS 32 (3) 682 - 685 0018-9464 1996/05 [Not refereed][Not invited]
   

  This paper describes a two-dimensional analysis of magnetic fields with thin magnetic materials using hypersingular integral equations. In this analysis, the thin materials are modeled as infinitesimally thin sheets, on which hypersingular integral equations for the vector potential are formulated, The hypersingular integral equation is discretized by boundary element method, on the basis of the Hadamard finite part integral, to numerically compute magnetic fields. The present method is shown to give an accurate magnetic field in a cylindrical magnetic shell with linear permeability. Moreover, numerical results for the shell with non-linear permeability are provided.
• H. Igarashi, K. Watanabe, T. Honma and A. Kost : "Regularization of Nearly Singular Boundary Integrals in Three-Dimensional Potential Problem", Boundary Element Communications, 7 : 164-170 (1996)＊

  1996 [Not refereed][Not invited]
  
• A finite element method for scalar Helmholtz equation with field singularities

  H Igarashi, T Honma

  IEICE TRANSACTIONS ON ELECTRONICS E79C (1) 131 - 138 0916-8524 1996/01 [Not refereed][Not invited]
   

  This paper describes a finite element method to obtain an accurate solution of the scalar Helmholtz equation with field singularities. It is known that the spatial derivatives of the eigenfunction of the scalar Helmholtz equation become infinite under certain conditions. These field singularities undermine the accuracy of the numerical solutions obtained by conventional finite element methods based on piecewise polynomials. In this paper, a regularized eigenfunction is introduced by subtracting the field singularities from the original eigenfunction. The finite element method formulated in terms of the regularized eigenfunction is expected to improve the accuracy and convergence of the numerical solutions. The finite element matrices for the present method can be easily evaluated since they do not involve any singular integrands. Moreover, the Dirichlet type boundary conditions are explicitly imposed on the variables using a transform matrix while the Neumann-type boundary conditions are implicitly imposed in the functional. The numerical results for three test problems show that the present method clearly improves the accuracy of the numerical solutions.
• STRATEGIES FOR THE ACCURATE COMPUTATION OF POTENTIAL DERIVATIVES IN BOUNDARY-ELEMENT METHOD - APPLICATION TO 2-DIMENSIONAL PROBLEMS

  H IGARASHI, T HONMA

  JOURNAL OF COMPUTATIONAL PHYSICS 119 (2) 244 - 251 0021-9991 1995/07 [Refereed][Not invited]
   

  This paper describes two strategies for the accurate computations of potential derivatives in boundary element methods. The first method regularizes the quasi singularity in a fundamental solution by referring the potential and its derivatives at the boundary point nearest to a calculation point in a domain. In the second method, a system of coupled equations for an unknown potential and its derivatives at a calculation point is solved to improve accuracy. Green's theorem unifies the derivation of the above methods, which are shown to be suitable for computer implementation. Numerical results show that the present methods considerably improve the accuracy in the computations of potential derivatives. The errors in the present methods are analyzed to evaluate their performance for general cases. Although this paper describes the regularization methods for only two-dimensional problems, it is suggested that those can be easily extended to three-dimensional problems. (C) 1995 Academic Press, Inc.
• REGULARIZED FORMULAS FOR BE ANALYSIS OF EDDY-CURRENT PROBLEMS

  H IGARASHI, T HONMA

  IEEE TRANSACTIONS ON MAGNETICS 31 (3) 1492 - 1495 0018-9464 1995/05 [Refereed][Not invited]
   

  This paper provides new regularized formulas for the boundary element analysis of the modified Helmholtz equation describing eddy current fields. The present formulas are shown to regularize near singularity in the kernels and effectively to improve the accuracy in the computation of fields near boundaries.
• A NUMERICAL COMPUTATION OF EXTERNAL Q OF RESONANT CAVITIES

  H IGARASHI, Y SUGAWARA, T HONMA

  IEEE TRANSACTIONS ON MAGNETICS 31 (3) 1642 - 1645 0018-9464 1995/05 [Refereed][Not invited]
   

  This paper describes a simple numerical method based on the finite element method for the analysis of the resonant frequencies and external Q values of a waveguide loaded cavity. The present method solves a second order proper equation with a damping term, which can be reduced to a linear one. It is shown that the present method provides the reasonable resonant frequencies and corresponding Q values for wide range of the electromagnetic coupling.
• Numerical estimation of bootstrap current in tokamaks under different approximations

  H IGARASHI, M YOSHIDA, T HONMA

  ADVANCED COMPUTATIONAL AND DESIGN TECHNIQUES IN APPLIED ELECTROMAGNETIC SYSTEMS 6 521 - 524 1995 [Refereed][Not invited]
  
• AN ANALYSIS OF ELECTROMAGNETIC-WAVES BY A COMPLEMENTARY FINITE-ELEMENT METHOD

  H IGARASHI, T HONMA

  IEEE TRANSACTIONS ON MAGNETICS 30 (5) 3104 - 3107 0018-9464 1994/09 [Refereed][Not invited]
   

  This paper describes an analysis of electromagnetic waves in a waveguide using the finite element method based on the complementary variational principle. The vector Helmholtz equation is represented in dual forms, in which the solenoidal and irrotational transverse fields are chosen to be unknowns, and they are approximated by the edge and facet elements, respectively. The dual representations are then shown to provide the lower bounds of the eigenfrequencies of a waveguide, with the aid of the complementary variational principle.
• A BOUNDARY-ELEMENT ANALYSIS OF MAGNETIC-FIELDS NEAR SURFACES

  H IGARASHI, T HONMA

  BOUNDARY ELEMENT TECHNOLOGY VIII 157 - 166 1993 [Refereed][Not invited]
  
• A VECTORIAL FINITE-ELEMENT FORMULATION FOR ELECTROMAGNETIC-WAVE PROPAGATION IN HELICAL SYSTEMS

  H IGARASHI, T HONMA

  JOURNAL OF APPLIED PHYSICS 71 (11) 5689 - 5693 0021-8979 1992/06 [Refereed][Not invited]
   

  This paper describes a vectorial finite element method for the analysis of electromagnetic waves propagating in helical systems. The present method can be as easily used as the methods for guided electromagnetic waves in systems with translational and axial symmetries. The functional for the vector Helmholtz equation is minimized using twisted coordinates in which the problem becomes two-dimensional. The spurious solutions, which do not satisfy the divergence-free condition, are removed on the basis of the penalty method. Two finite element equations for the covariant and contravariant components of electromagnetic fields are derived and boundary conditions for both formulations are described. The present method is applied to the analysis of a twisted waveguide with a rectangular cross section and the numerical solutions are shown to be in good agreement with the perturbed solutions for a small helical pitch.
• ON AXIALLY AND HELICALLY SYMMETRICAL FUNDAMENTAL-SOLUTIONS TO MODIFIED HELMHOLTZ-TYPE EQUATIONS

  H IGARASHI, T HONMA

  APPLIED MATHEMATICAL MODELLING 16 (6) 314 - 319 0307-904X 1992/06 [Refereed][Not invited]
   

  Fundamental solutions to modified Helmholtz-type equations, which often appear in electrostatics and magnetostatics, are investigated. In particular, this paper defines the relation among two-dimensional (or symmetric) fundamental solutions that play an important role in boundary element analyses. The fundamental solutions for axially and helically symmetric systems are derived from the integration of three-dimensional fundamental solutions along a ring and a helix, respectively. These derivations are performed on the basis of the Fourier-Bessel theorem.
• BE AND FE SOLUTIONS TO OPEN BOUNDARY POTENTIAL PROBLEMS WITH HELICAL SYMMETRY

  H IGARASHI, T HONMA

  IEEE TRANSACTIONS ON MAGNETICS 28 (2) 1671 - 1674 0018-9464 1992/03 [Refereed][Not invited]
   

  This paper presents boundary element (BE) and finite element (FE) solutions to open boundary potential problems with helical symmetry. The BE and FE equations are introduced in the twisted coordinates in which helical potential fields can be regarded as being two-dimensional. In the FE analysis, 'transfinite' elements are used for modeling open boundaries. Magnetic fields around a helical solenoid are analyzed using the above mentioned methods and those numerical solutions are shown to be in good agreement with analytic solutions. Moreover, electric fields around a twisted-pair line are calculated and it is shown that the fields come to concentrate in the vicinity of the lines as the helical pitch is increased.
• A BOUNDARY ELEMENT ANALYSIS OF HELICALLY SYMMETRICAL POTENTIAL FIELDS

  H IGARASHI, T HONMA

  ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS 10 (2) 131 - 136 0955-7997 1992 [Refereed][Not invited]
   

  This paper presents a boundary element analysis of helically symmetric potential fields. A two dimensional boundary integral equation is introduced in general curvilinear coordinates. On the basis of this formulation, a boundary integral equation for helically symmetric potential problems is obtained using twisted coordinates. Moreover, the boundary element solution by the present scheme is compared with perturbation and finite element solutions for a simple potential problem and it is shown that the boundary element solution is in good agreement with the finite element solution for arbitrary helical pitch values while the perturbed solution becomes inaccurate for large pitch values.
• A FINITE-ELEMENT ANALYSIS OF TE MODES IN TWISTED WAVE-GUIDES

  H IGARASHI, T HONMA

  IEEE TRANSACTIONS ON MAGNETICS 27 (5) 4052 - 4055 0018-9464 1991/09 [Refereed][Not invited]
   

  In this paper, the scalar Helmholtz equation is solved by the use of finite element methods to analyze the TE mode in the twisted waveguide. For this purpose, on the basis of the weighted residual method, a two dimensional integral equation described in the twisted coordinates is introduced by reducing that in the general curvilinear coordinates. After the finite element formulation, it is shown that the numerical solution monotonously converges with increasing the number of nodes. Moreover, the cut-off constant and the dispersion relation calculated by the present scheme are shown to be in good agreement with those calculated by the perturbation method. Furthermore, on the basis of the numerical results, some comments are offered on the TE mode distributions in a twisted rectangular waveguide and on the influence of the shift of the waveguide on those distributions.
• BOUNDARY ELEMENT ANALYSIS OF ELECTROMAGNETIC-FIELDS IN HELICALLY SYMMETRICAL SYSTEM

  H IGARASHI, T HONMA

  BOUNDARY ELEMENT TECHNOLOGY VI 65 - 76 1991 [Refereed][Not invited]
  
• AN EQUILIBRIUM-ANALYSIS OF HELICALLY SYMMETRICAL PLASMAS USING BOUNDARY ELEMENT METHOD

  H IGARASHI, T HONMA

  IEEE TRANSACTIONS ON MAGNETICS 26 (5) 1774 - 1776 0018-9464 1990/09 [Refereed][Not invited]
  
• AN ANALYSIS OF ION-BEAM TRAJECTORIES BY USING BOUNDARY ELEMENT METHOD

  S SHIRAKAWA, H IGARASHI, T HONMA

  IEEE TRANSACTIONS ON MAGNETICS 26 (2) 555 - 558 0018-9464 1990/03 [Refereed][Not invited]
  

MISC

• On eddy current analysis using homogenization and Dowell methods

  五十嵐一, LIU Qiao, YIN Shuli  電気学会研究会資料(Web)  (SA-24-015-027/RM-24-015-027)  2024
• 深層学習とトポロジー最適化を併用した電気機器構造の高速逆解析手法に関する検討—A study on the High-Speed Inverse Analysis Method of Electrical Device Structures Using Deep Learning and Topology Optimization—静止器/回転機合同研究会・電磁界数値計算技術とその応用

  岩田 和久, 佐々木 秀徳, 五十嵐 一, 中川 大輔, 上田 智哉  電気学会研究会資料. RM / 電気学会回転機研究会 [編]  2023-  (68-79)  29  -34  2023/08/29
• Accelerating Topology Optimization for Electric Motors with Deep Learning

  佐々木秀徳, 五十嵐一  電気学会全国大会講演論文集(CD-ROM)  2023-  2023
• A study on the High-Speed Inverse Analysis Method of Electrical Device Structures Using Deep Learning and Topology Optimization

  岩田和久, 佐々木秀徳, 五十嵐一, 中川大輔, 上田智哉  電気学会研究会資料(Web)  (SA-23-069-080/RM-23-068-079)  2023
• Extended Cauer Equivalent Circuit Model of Inductors: Representing Multi-resonant Characteristics Due to Parasitic Capacitance

  Yuki Sato, Kenji Kawano, Hajime Igarashi, Hirokazu Matsumoto  Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC  2023-March-  3294  -3301  2023  [Refereed]
   

  This study presents an extended Cauer circuit model of power inductors that can represent both eddy current effects and capacitive properties. This model is valid from DC to higher frequencies beyond the resonance because it considers the skin and proximity effects of windings as well as the parasitic capacitance. The inductive part is represented by a Cauer circuit whose circuit parameters are recursively determined from the frequency properties of the inductor obtained through measurements or simulations. Moreover, the impedance profile around the resonance is expressed by introducing hierarchical RLC series circuits to the Cauer circuit. The extended Cauer circuit can be embedded in circuit simulators once constructed to perform time-domain simulations.
• 自動車駆動用モータにおける磁気回路設計の自動化と高速化に向けたモータの磁気特性予測の検討(第2報)—Examination of magnetic characteristic prediction of motors for automation and speeding up of magnetic circuit design in automobile drive motors(2nd report)—静止器/回転機合同研究会・電磁界数値計算技術とその応用

  中川 大輔, 上田 智哉, 佐々木 秀徳, 五十嵐 一  電気学会研究会資料. RM / 電気学会回転機研究会 [編]  2022-  (83-103)  37  -42  2022/09/30
• Study on Generalization of the Prediction Model of Rotating Machine Characteristics Using the Gap Flux Density Distribution

  佐々木秀徳, 五十嵐一, 中川大輔, 上田智哉  電気学会研究会資料(Web)  (SA-22-018-032/RM-22-018-032)  2022
• Basic Study on Multi-Step Topology Optimization of Motor Structures Using Deep Learning

  佐々木秀徳, 五十嵐一, 中川大輔, 上田智哉  電気学会産業応用部門大会(CD-ROM)  2022-  2022
• Prediction of IPMSM performance using deep learning with considering the position of magnets and distribution of rotor core

  岩田和久, 佐々木秀徳, 五十嵐一, 中川大輔, 上田智哉  MAGDAコンファレンス講演論文集  31st (CD-ROM)-  2022
• Time-Domain Homogenized Finite Eddy Current Analysis using Recursive Convolution Method

  Yuki Sato, Shingo Hiruma, Hajime Igarashi  CEFC 2022 - 20th Biennial IEEE Conference on Electromagnetic Field Computation, Proceedings  2022  

  This paper presents a novel method to effectively and accurately perform time-domain homogenized finite element analysis of the multi-turn coil windings. In this method, the macroscopic complex permeability is represented by the partial fraction and then the inverse Laplace transformation is performed by the recursive convolution method. It is shown that the results obtained by the present method are in good agreement with those obtained by the conventional FE analysis while the former works about 100 times faster than the latter.
• Error Estimator for Continued Fraction Approximation of Linear Dynamical System

  Shingo Hiruma, Stephane Clenet, Hajime Igarashi  CEFC 2022 - 20th Biennial IEEE Conference on Electromagnetic Field Computation, Proceedings  2022  

  Cauer ladder network (CLN) method, which enables to approximate the eddy current problems by a Cauer circuit, can be generalized to the continued fraction approximation of a transfer function of a finite dimensional linear dynamical system. A new error estimator for the continued fraction approximation is proposed in the paper, which provides guaranteed upper bounds of the error of reduction.
• A Study on Shape Optimization of IPM Motors Using Boolean Geometry Projection Method and Topology Optimization

  大友佳嗣, 阿部貴志, 五十嵐一, 加藤鷹志, 栗田洋敬  電気学会研究会資料(Web)  (SA-22-080-100/RM-22-083-103)  2022
• A Basic Study on Optimization of Permanent Magnet Configuration Using Boolean Geometry Projection Method for IPM Motors

  大友佳嗣, 五十嵐一, 加藤鷹志, 栗田洋敬  電気学会全国大会講演論文集(CD-ROM)  2022-  2022
• Core Loss Measurement of Metal Composite Materials Using Resonant Method Under DC Bias Field

  上原裕二, 寺内直也, 佐藤奈津子, 松田好文, 長野将典, 大友佳嗣, 五十嵐一  電気学会研究会資料(Web)  (SA-22-001-004.006-017/RM-22-001-004.006-017)  2022
• A Basic Study on Iron Loss Prediction for Inductors Using Response Surface Method

  大友佳嗣, 五十嵐一, 上原裕二, 寺内直也, 佐藤奈津子, 松田好文, 長野将典  電気学会研究会資料(Web)  (SA-22-001-004.006-017/RM-22-001-004.006-017)  2022
• 渦電流と寄生容量を考慮した準定常場解析の基礎検討(その2)—A study on quasi-static electromagnetic field analysis including eddy currents and capacitive effects(2)—静止器/回転機合同研究会・電磁界数値計算技術とその応用

  比留間 真悟, 五十嵐 一  電気学会研究会資料. SA / 電気学会静止器研究会 [編]  2021-  (1・3-14)  31  -36  2021/03
• A Basic Study on Equivalent Circuit Model Considering Displacement and Eddy Currents

  大友佳嗣, 五十嵐一  日本機械学会計算力学講演会論文集(CD-ROM)  34th-  2021
• A Basic Study on Equivalent Circuit Model Considering Displacement Current and Skin and Proximity Effects

  大友佳嗣, 五十嵐一  電気学会研究会資料(Web)  (SA-21-048-065/RM-21-069-086)  2021
• A Basic Study on 2.5-D Multi-Phase Topology Optimization of Permanent Magnet Motor

  大友佳嗣, 五十嵐一, 佐藤智宏, 末次恵久, 藤岡英二  電気学会産業応用部門大会(CD-ROM)  2021-  2021
• Characterization of Permanent Magnet Motor by Analytical Method

  山崎温生, 大友佳嗣, 五十嵐一  電気・情報関係学会北海道支部連合大会講演論文集(CD-ROM)  2021-  2021
• Topology Optimization of Electric Devices Using Digital Annealer

  丸尾昭人, 添田武志, 五十嵐一  電気学会全国大会講演論文集(CD-ROM)  2021-  2021
• A study on quasi-static electromagnetic field analysis including eddy currents and capacitive effects: II

  比留間真悟, 五十嵐一  電気学会研究会資料  (SA-21-001-014/RM-21-001-014)  2021
• Current characteristics prediction of permanent magnet motor using deep learning and its application to topology optimization

  青柳泰我, 大友佳嗣, 五十嵐一, 佐々木秀徳, 日高勇気, 有田秀哲  電気学会研究会資料  (SA-21-015-028/RM-21-015-028)  2021
• Automatic Design of Permanent Magnet Motor Using Monte Carlo Tree Search

  佐藤駿輔, 五十嵐一  電気学会研究会資料  (SA-21-015-028/RM-21-015-028)  2021
• Design Optimization of Coils and Magnets in Vibration Energy Harvester Using Digital Annealer

  Akito Maruo, Hirotaka Oshima, Hajime Igarashi  CEFC 2020 - Selected Papers from the 19th Biennial IEEE Conference on Electromagnetic Field Computation  2020/11/16  

  Vibration energy harvesters (VEHs), which convert ambient vibration energy into electrical energy, have been attracted great attentions as an energy source for wireless sensors in IoT technology. A new method using Digital Annealer for the simultaneous optimization of the coils and magnet arrays of an induction-type VEH is proposed to improve the performance of a VEH. It is found that the optimal arrangement, which strongly depends on the gap length between the coils and magnet arrays, improves the performance.
• Multi-material Topology Optimization of Permanent Magnet Motor with Arbitrary Adjacency Relationship of Materials

  Hayaho Sato, Shingo Hiruma, Hajime Igarashi  CEFC 2020 - Selected Papers from the 19th Biennial IEEE Conference on Electromagnetic Field Computation  2020/11/16  

  This study introduces a novel multi-material topology optimization method that can represent material distribution with an arbitrary adjacency relationship. Different state spaces for the representation of material distribution are applied to the optimization of a permanent magnet motor for comparison. It is shown that the proposed method yields a higher permanent magnet motor torque performance compared to that of conventional methods. The effect of topology optimization setting on the optimized motor structure is also discussed.
• Basic study on deep learning of torque performance of rotating machines based on magnetic field distribution

  佐々木 秀徳, 日高 勇気, 有田 秀哲, 伊藤 一将, 五十嵐 一  電気学会研究会資料. SA  2020-  (51)  51  -56  2020/09/04
• A Basic Study on Three-Dimensional Topology Optimization of Permanent Magnet Motors

  大友 佳嗣, 五十嵐 一  電気学会研究会資料. SA  2020-  (51)  45  -50  2020/09/04
• A study on quasi-static electromagnetic field analysis including eddy currents and capacitive effects

  比留間 真悟, 五十嵐 一  電気学会研究会資料. SA  2020-  (31)  93  -102  2020/09/03
• Inverse Modeling of Inductors Using Gauss Kernel Regression

  佐藤 佑樹, 河野 健二, 五十嵐 一  電気学会研究会資料. SA  2020-  (31)  43  -48  2020/09/03
• 動的モード関数のStieltjes連分数およびCauer回路表示について (諸科学分野を結ぶ基礎学問としての数値解析学)

  比留間 真悟, 五十嵐 一  数理解析研究所講究録  (2167)  75  -81  2020/07
• Topology optimization of rotating machines using Explainable AI : a fundamental study

  佐々木 秀徳, 日高 勇気, 伊藤 一将, 田中 敏則, 五十嵐 一  電気学会研究会資料. RM  2020-  (16)  25  -30  2020/01/24
• Optimization of magnet design of SPM motor with Digital Annealer to improve torque properties

  佐々木 真, 丸尾 昭人, 大島 弘敬, 五十嵐 一  電気学会研究会資料. RM  2020-  (16)  13  -18  2020/01/24
• 3D optimization of magnet array for thin SPM motor using Digital Annealer

  丸尾 昭人, 大島 弘敬, 五十嵐 一  電気学会研究会資料. RM  2020-  (16)  7  -12  2020/01/24
• Topology Optimization of PM Motors: representation of different magnetizations

  佐藤駿輔, 比留間真悟, 岡本和也, 五十嵐一  電気学会全国大会講演論文集(CD-ROM)  2020-  2020
• Cauer circuit representation of leakage impedance of transformer winding using complex permeability

  比留間真悟, 五十嵐一  電気学会全国大会講演論文集(CD-ROM)  2020-  2020
• Study on Topology Optimization Using Gabor Filter: Application to SPM motor

  大友佳嗣, 五十嵐一  電気学会全国大会講演論文集(CD-ROM)  2020-  2020
• Optimization of position and current for transverse flux induction heater

  佐々木隆宏, 五十嵐一, 下谷俊人, 橋本英二, 今成宏幸  MAGDAコンファレンス講演論文集  29th (CD-ROM)-  2020
• Design of Thin Dielectric Lens for Millimeter Wave Waveguide Slot Antenna

  戸賀瀬駿, 伊藤桂一, 田中将樹, 五十嵐一  MAGDAコンファレンス講演論文集  29th (CD-ROM)-  2020
• Generation of various permanent magnet motor shapes by multi objective topology optimization

  青柳泰我, 佐藤駿輔, 大友佳嗣, 五十嵐一  MAGDAコンファレンス講演論文集  29th (CD-ROM)-  2020
• Multi-material and multi-objective optimization of IPM motor considering constraints

  林翔吾, 比留間真悟, 五十嵐一  MAGDAコンファレンス講演論文集  29th (CD-ROM)-  2020
• Analysis of nonlinear magnetic properties of soft magnetic composite using 2D and 3D discrete element methods

  Hayaho Sato, Akito Maruo, Hajime Igarashi  INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS  64-  (1-4)  483  -492  2020  [Not refereed][Not invited]
   

  This paper presents the three-dimensional modeling of soft magnetic composite (SMC) based on the discrete element method. The proposed method makes it possible to take the possible contact among the magnetic particles in SMC as well as the distributed particle size into consideration. Based on this modeling, the macroscopic B-H characteristics is computed with the finite element method considering magnetic saturation. It is shown that the three-dimensional model of SMC can have larger initial permeability in comparison with the two-dimensional model even if they have the same filling factor.
• Topology Optimization of Electric Motor: Suppression of Mechanical Vibrations

  岡本和也, 五十嵐一  MAGDAコンファレンス講演論文集  28th-  350‐351  2019/10/30  [Not refereed][Not invited]
  
• Multi‐objective Topology Optimization Using Deep Learning―Comparison of Classification with Regression―

  土居周平, 浅沼丈, 五十嵐一  MAGDAコンファレンス講演論文集  28th-  348‐349  2019/10/30  [Not refereed][Not invited]
  
• Homogenized finite element analysis of reduction in copper loss of magnetically shielded wire coils

  藤田祥伍, 藤田祥伍, 五十嵐一  MAGDAコンファレンス講演論文集  28th-  238‐239  2019/10/30  [Not refereed][Not invited]
  
• Topology Optimization of Magnetic Couplers for Wireless Power Transfer Considering Electromagnetic Shields

  Yoshitsugu Otomo, Hajime Igarashi  IECON Proceedings (Industrial Electronics Conference)  2019-October-  4341  -4344  2019/10  [Not refereed][Not invited]
   

  © 2019 IEEE. This paper presents topology optimization of magnetic couplers for wireless power transfer (WPT) device considering electromagnetic shields. In this optimization, the magnetic coupler shape for WPT is represented by the Gaussian basis functions. The coupler shape is optimized so that the coupling factor is maximized while the leakage flux is minimized. Moreover, a robust optimization method is proposed to keep the interlinkage flux as large as possible against misalignment between the coils. It is shown by the computational and experimental results that the optimized coupler outperforms the conventional coupler.
• Study on Topology Optimization Using Gabor Filter : Application to Synchronous Reluctance Motor

  大友 佳嗣, 五十嵐 一  電気学会研究会資料. SA  2019-  (73)  41  -45  2019/09/13
• Acceleration of Multi‐objective Optimization Using Regression Deep Neural Network

  土居周平, 浅沼丈, 五十嵐一  電気学会研究会資料  (SA-19-073-091/RM-19-093-111)  23‐28  2019/09/12  [Not refereed][Not invited]
  
• A simplified proper orthogonal decomposition for fast analysis of IPM motors

  岡本和也, 五十嵐一, 坂本宏紀  電気学会研究会資料  (SA-19-073-091/RM-19-093-111)  71‐76  2019/09/12  [Not refereed][Not invited]
  
• Study on additional learning method in deep learning

  佐々木秀徳, 佐々木秀徳, 日高勇気, 伊藤一将, 田中敏則, 大友佳嗣, 五十嵐一  電気学会研究会資料  (SA-19-073-091/RM-19-093-111)  29‐34  2019/09/12  [Not refereed][Not invited]
  
• IPMモータの複数材料トポロジー最適化

  佐藤駿輔, 比留間真悟, 五十嵐一  電気学会電子・情報・システム部門大会講演論文集(CD-ROM)  2019-  ROMBUNNO.PS3‐6  2019/08/28  [Not refereed][Not invited]
  
• 損失を考慮したミアンダインダクタの3次元形状最適化

  佐々木隆宏, 五十嵐一  電気学会電子・情報・システム部門大会講演論文集(CD-ROM)  2019-  ROMBUNNO.PS6‐2  2019/08/28  [Not refereed][Not invited]
  
• 回帰型CNNによるトポロジー最適化の高速化

  土居周平, 浅沼丈, 五十嵐一  電気学会電子・情報・システム部門大会講演論文集(CD-ROM)  2019-  ROMBUNNO.PS3‐5  2019/08/28  [Not refereed][Not invited]
  
• 均質化有限要素解析による時間領域解析 : コイル巻線渦電流損失解析への適用—Time-domain analysis using homogenization-based finite element method : Application to analysis of eddy current loss in coil winding—静止器 回転機合同研究会・電磁界数値計算技術とその応用

  比留間 真悟, 五十嵐 一  電気学会研究会資料. SA / 電気学会静止器研究会 [編]  2019-  (1-15)  25  -30  2019/03/05
• Cauer‐Equivalent Circuit of Power Inductor Considering Magnetic Hysteresis Loss

  佐藤佑樹, 河野健二, 五十嵐一  電気学会研究会資料  (SA-19-001-015/RM-19-001-015)  7‐12  2019/03/05  [Not refereed][Not invited]
  
• Three‐dimensional topology optimization of claw‐pole alternator

  大友佳嗣, 五十嵐一, 日高勇気, 小松大河, 山田正樹  電気学会研究会資料  (SA-19-001-015/RM-19-001-015)  31‐34  2019/03/05  [Not refereed][Not invited]
  
• Time‐domain analysis using homogenization‐based finite element method: Application to analysis of eddy current loss in coil winding

  比留間真悟, 五十嵐一  電気学会研究会資料  (SA-19-001-015/RM-19-001-015)  25‐30  2019/03/05  [Not refereed][Not invited]
  
• 応答曲面とニューラルネットワークを用いた誘導加熱装置の3次元構造最適化

  石田智和, 五十嵐一, 下谷俊人, 橋本英二, 今成宏幸  電気学会全国大会講演論文集(CD-ROM)  2019-  ROMBUNNO.5‐131  2019/03/01  [Not refereed][Not invited]
  
• 異方性と渦電流を考慮した圧粉磁芯の均質化モデル

  藤田祥伍, 五十嵐一  電気学会全国大会講演論文集(CD-ROM)  2019-  ROMBUNNO.5‐130  2019/03/01  [Not refereed][Not invited]
  
• 随伴変数法を用いた等価回路定数の決定 リッツ線コイルへの適用

  大友佳嗣, 五十嵐一  電気学会全国大会講演論文集(CD-ROM)  2019-  ROMBUNNO.4‐034  2019/03/01  [Not refereed][Not invited]
  
• Topology Optimization of Magnetic Cores for EV Wireless Charging Device

  OTOMO Yoshitsugu, IGARASHI Hajime  The Proceedings of The Computational Mechanics Conference  2019-  (0)  43  -43  2019  

  This paper presents topology optimization of magnetic cores for EV wireless charging device. In this optimization, the magnetic core shape for wireless power transfer (WPT) is represented by the Gaussian basis function. The core shape is optimized so as to maximize the coupling factor. In addition, robustness against misalignment between transmitting and receiving coils is taken into account in the optimization. It is found that the optimized core shape effectively increases the net magnetic flux interlinked with the receiving coil, and outperforms the conventional core shape.

• Construction of control model for induction heating device using proper orthogonal decomposition: a basic study

  下谷俊人, 下谷俊人, 五十嵐一, 橋本英二, 今成宏幸  MAGDAコンファレンス講演論文集  27th-  80‐83  2018/10/20  [Not refereed][Not invited]
  
• Design of Dielectric Cover for Millimeter Wave Waveguide Slot Antenna

  伊藤桂一, 滝田和真, 五十嵐一  MAGDAコンファレンス講演論文集  27th-  92‐93  2018/10/20  [Not refereed][Not invited]
  
• 機械振動を考慮したIPMモータのトポロジー最適化の検討

  岡本和也, 五十嵐一  電気学会電子・情報・システム部門大会講演論文集(CD-ROM)  2018-  ROMBUNNO.MC1‐4  2018/09/05  [Not refereed][Not invited]
  
• 回転機のトポロジー多目的最適化への深層学習の適用について

  土居周平, 五十嵐一  電気学会電子・情報・システム部門大会講演論文集(CD-ROM)  2018-  ROMBUNNO.MC6‐4  2018/09/05  [Not refereed][Not invited]
  
• 振動発電のための平面磁石配置の最適設計

  丸尾昭人, 五十嵐一  電気学会電子・情報・システム部門大会講演論文集(CD-ROM)  2018-  ROMBUNNO.MC3‐1  2018/09/05  [Not refereed][Not invited]
  
• 伝達関数のStieltjes連分数展開による電磁機器の等価回路生成

  比留間真悟, 五十嵐一  電気学会電子・情報・システム部門大会講演論文集(CD-ROM)  2018-  ROMBUNNO.MC7‐3  2018/09/05  [Not refereed][Not invited]
  
• 随伴変数法を用いた電気機器の等価回路定数の決定

  大友佳嗣, 五十嵐一  電気学会電子・情報・システム部門大会講演論文集(CD-ROM)  2018-  ROMBUNNO.MC7‐4  2018/09/05  [Not refereed][Not invited]
  
• Time-domain analysis using homogenization-based finite element method: Continued fraction representation of complex permeability of unit cell

  比留間真悟, 五十嵐一  電気学会研究会資料  (SA-18-053-059.061-068/RM-18-072-078.080-087)  51‐56  2018/08/21  [Not refereed][Not invited]
  
• 均質化有限要素法とインピーダンス境界条件を用いた渦電流変位センサの電磁界解析

  藤田祥伍, 五十嵐一  電気学会全国大会講演論文集(CD-ROM)  2018-  ROMBUNNO.5‐119  2018/03/05  [Not refereed][Not invited]
  
• 非接触給電装置の磁気コアの3次元トポロジー最適化

  大友佳嗣, 五十嵐一  電気学会全国大会講演論文集(CD-ROM)  2018-  ROMBUNNO.5‐125  2018/03/05  [Not refereed][Not invited]
  
• 圧粉磁心の複素透磁率の粒子形状依存性

  丸尾昭人, 五十嵐一  電気学会全国大会講演論文集(CD-ROM)  2018-  ROMBUNNO.5‐129  2018/03/05  [Not refereed][Not invited]
  
• セイシキ カイテンキ ゴウドウ ケンキュウカイ ・ デンジカイ スウチ ケイサン ギジュツ 、 イッパン

  ヒルマ シンゴ, イガラシ ハジメ  電気学会研究会資料. SA / 電気学会静止器研究会 [編]  2018-  (1-15)  73  -80  2018/01/23
• Topology optimization of rotating machines using deep learning: II

  佐々木秀徳, 五十嵐一  電気学会研究会資料  (SA-18-016-031/RM-18-016-031)  29‐33  2018/01/23  [Not refereed][Not invited]
  
• Multi-objective parameter optimization by genetic algorithm in magnetic simulation with a magnetic hysteresis model

  下川聡, 大島弘敬, 清水香壱, 上原裕二, 藤崎淳, 古屋篤史, 五十嵐一  電気学会研究会資料  (SA-18-016-031/RM-18-016-031)  17‐22  2018/01/23  [Not refereed][Not invited]
  
• A study on orthogonal polynomials and Stieltjes continued fraction

  比留間真悟, 五十嵐一  電気学会研究会資料  (SA-18-001-015/RM-18-001-015)  73‐80  2018/01/23  [Not refereed][Not invited]
  
• AI技術と高精度電磁界解析を用いた最適設計

  五十嵐一, 佐々木秀徳  電気学会全国大会講演論文集(CD-ROM)  2018-  2018
• Wireless Sensor Using Electromagnetic Vibration Energy Harvester

  杉澤健, 丸尾昭人, 蟹江俊仁, 五十嵐一  日本AEM学会誌  26-  (2)  2018
• Wireless Sensor Using Electromagnetic Vibration Energy Harvester

  杉澤健, 丸尾昭人, 五十嵐一  MAGDAコンファレンス講演論文集  26th-  (2)  295‐300  -412  2017/10/26  [Not refereed][Not invited]
   

  A wireless sensor which is powered by a vibration energy harvester (VEH) with magnetic induction is proposed. The wireless sensor is composed of the VEH device, a voltage multiplier, boost converter and wireless communication module. The VEH device has double magnetic circuits which form almost magnetically closed paths. It is shown that the wireless sensor can work for input acceleration 0.1 G at around 30 Hz.

• Topology optimization of dielectric lens antenna using normalized Gaussian network

  伊藤桂一, 五十嵐一  電子情報通信学会技術研究報告  117-  (244(MW2017 82-110))  123‐127  2017/10/12  [Not refereed][Not invited]
  
• Synthesis of equivalent circuit of a system including macroscopic permeability

  比留間真悟, 五十嵐一  電気学会静止器研究会資料  SA-17-  (52-66)  67‐72  -72  2017/09/21  [Not refereed][Not invited]
  
• Three-dimensional FE analysis of Litz-wire based on homogenization method

  大友佳嗣, 五十嵐一, 鈴木理明, 佐野広征, 山田隆, 上田幸平, 西田雄亮  電気学会静止器研究会資料  SA-17-  (67-81)  7‐12  2017/09/21  [Not refereed][Not invited]
  
• Topology optimization of rotating machines using deep learning: a fundamental study

  佐々木秀徳, 五十嵐一  電気学会静止器研究会資料  SA-17-  (67-81)  83‐88  2017/09/21  [Not refereed][Not invited]
  
• Model Order Reduction and Synthesis of Equivalent Circuit

  五十嵐 一, 佐藤 佑樹  電気学会誌 = The journal of the Institute of Electrical Engineers of Japan  137-  (8)  545  -548,527  2017/08  [Not refereed][Invited]
  
• Numerical analysis of wireless power transfer system using homogenized FEM

  大友 佳嗣, 藤田 祥伍, 五十嵐 一  電気学会研究会資料. RM  2017-  (16)  41  -46  2017/01/19
• Time-Domain FE Analysis of Soft Magnetic Composite Using Homogenization

  佐藤 佑樹, 五十嵐 一  電気学会研究会資料. RM  2017-  (2)  51  -56  2017/01/18
• 深層学習によるトポロジー最適化の高速化-基礎的検討

  佐々木秀徳, 五十嵐一  電気・情報関係学会北海道支部連合大会講演論文集(CD-ROM)  2017-  2017
• 自己随伴Lanczos法を用いた伝達関数の連分数近似

  比留間真悟, 五十嵐一  電気・情報関係学会北海道支部連合大会講演論文集(CD-ROM)  2017-  2017
• 渦電流損失を考慮した非接触給電系の解析

  大友佳嗣, 五十嵐一  電気・情報関係学会北海道支部連合大会講演論文集(CD-ROM)  2017-  2017
• Preface to Special Issue on Electromagnetic Field Analysis of Electric Power Apparatus

  Igarashi Hajime  IEEJ Transactions on Power and Energy  137-  (3)  156  -156  2017  [Not refereed][Invited]
   

  <p>計算機を用いた電磁界解析手法には，有限要素法，境界要素法，時間領域差分法（FDTD 法），モーメント法，部分要素等価回路法（PEEC）などがあるが，電力・電気機器の電磁界解析には非線形解析に適し，柔軟な形状表現が可能な有限要素法が広く用いられている。有限要素法は1960 年</p>
• Introduction: Electromagnetic Field Analysis Realizes Model-based Design

  IGARASHI Hajime  The Journal of the Institute of Electrical Engineers of Japan  137-  (8)  528  -529  2017  [Not refereed][Invited]
   

  <p>1．電磁界解析による機器設計の広がり</p><p>研究開発において，理論的方法，実験的方法に加え，第三の方法として数値シミュレーションが活用されてきた。電気機器の設計においても，電磁界解析をはじめとした数値シミュレーションが積極的に導入されてきた。初期には，電磁界解析は現象の解析や可視化など補完的な役割を</p>
• Electromagnetic field analysis of electric power apparatus: The state of the art

  Hajime Igarashi, Akira Ahagon, Yoshifumi Okamoto, Daigo Yonetsu  IEEJ Transactions on Power and Energy  137-  (3)  157  -161  2017  [Not refereed][Invited]
   

  This paper surveys the recent advances in electromagnetic field analysis of electric power apparatus. The model order reduction and homogenization methods are effective to reduce the computational time. The Play model can express vector hysteresis characteristics with small computational burden. The topology optimization can lead to novel design of electric apparatus. The contactless power transfer and induction heat devices are effectively analyzed by the finite element method.
• 電磁誘導型振動発電機の広帯域化のための設計最適化

  杉澤健, 丸尾昭人, 五十嵐一  日本機械学会計算力学講演会論文集(CD-ROM)  29th-  ROMBUNNO.108  2016/09/21  [Not refereed][Not invited]
  
• 電波吸収体構造のトポロジー最適化

  上原雅広, 五十嵐一  日本機械学会計算力学講演会論文集(CD-ROM)  29th-  ROMBUNNO.167  2016/09/21  [Not refereed][Not invited]
  
• Homogenization Analysis of Magnetoplated Wires

  藤田祥伍, 五十嵐一  電子情報通信学会技術研究報告  116-  (212(EST2016 42-55))  7‐12  2016/08/31  [Not refereed][Not invited]
  
• Time-Domain Finite Element Analysis of Multi-Scale Problems Using Homogenization and Model Order Reduction

  佐藤佑樹, 五十嵐一  電子情報通信学会技術研究報告  116-  (212(EST2016 42-55))  109‐114  2016/08/31  [Not refereed][Not invited]
  
• The Topology Optimization of Motor using Basis Function

  佐々木秀徳, 五十嵐一  電子情報通信学会技術研究報告  116-  (212(EST2016 42-55))  301‐306  2016/08/31  [Not refereed][Not invited]
  
• 3D Topology Optimization of Small Dielectric Lens for Antenna

  伊藤桂一, 五十嵐一  電子情報通信学会技術研究報告  116-  (212(EST2016 42-55))  157‐160  2016/08/31  [Not refereed][Not invited]
  
• Integral equation using complex permeability: analysis of fine conductive lines

  比留間真悟, 藤田祥伍, 五十嵐一  電子情報通信学会技術研究報告  116-  (212(EST2016 42-55))  19‐24  2016/08/31  [Not refereed][Not invited]
  
• Topology Optimization of Rotation Machine using On-Off Method with Variable Design Region

  日高勇気, 日高勇気, 五十嵐一  電子情報通信学会技術研究報告  116-  (212(EST2016 42-55))  295‐300  2016/08/31  [Not refereed][Not invited]
  
• 損失を考慮した埋込磁石同期モータ固定子形状のトポロジー最適化

  佐々木秀徳, 古井真太郎, 五十嵐一  電気学会全国大会講演論文集(CD-ROM)  2016-  ROMBUNNO.5‐006  2016/03/05  [Not refereed][Not invited]
  
• Generation of Equivalent Circuit Using Model Order Reduction (2)-Generation of Cauer-Equivalent Circuit-

  佐藤佑樹, 佐藤佑樹, 下谷俊人, 五十嵐一  電気学会静止器研究会資料  SA-16-  (18-32.34)  1‐6  2016/01/20  [Not refereed][Not invited]
  
• A Basic Investigation of Many-objective Optimization of Electric Devices and Machines

  佐藤孝洋, 藤田真史, 五十嵐一  電気学会静止器研究会資料  SA-16-  (18-32.34)  23‐28  2016/01/20  [Not refereed][Not invited]
  
• Topology optimization of IPM motors considering iron losses

  古井真太郎, 五十嵐一, 坂本宏紀, 阿部崇志, 小倉和也  電気学会静止器研究会資料  SA-16-  (18-32.34)  29‐34  2016/01/20  [Not refereed][Not invited]
  
• Shape Optimization of 3-Dimentional Machines with Axis Inversion Periodic Boundary Conditions

  日高勇気, 日高勇気, 五十嵐一  電気学会静止器研究会資料  SA-16-  (18-32.34)  65‐68  2016/01/20  [Not refereed][Not invited]
  
• 群知能最適化手法に関する基礎検討

  LIU Xuanqi, 佐々木秀徳, 五十嵐一  電気・情報関係学会北海道支部連合大会講演論文集(CD-ROM)  2016-  2016
• IPMモータのトポロジー最適化における形状変化

  佐々木秀徳, 五十嵐一  電気・情報関係学会北海道支部連合大会講演論文集(CD-ROM)  2016-  2016
• 均質化有限要素法を用いた非接触給電系の等価回路生成

  大友佳嗣, 藤田祥伍, 五十嵐一  MAGDAコンファレンス講演論文集  25th-  2016
• ガウス基底を用いた回転機フラックスバリアの形状最適化

  佐々木秀徳, 五十嵐一  電気学会産業応用部門大会(CD-ROM)  2016-  ROMBUNNO.Y‐102  2016  [Not refereed][Not invited]
  
• 閉磁路型振動発電機の提案

  杉澤健, 五十嵐一  MAGDAコンファレンス講演論文集  24th-  307‐312  2015/11/12  [Not refereed][Not invited]
  
• 半球付誘電体カバーを装着した平面アンテナの数値解析

  伊藤桂一, 宮田克正, 五十嵐一  MAGDAコンファレンス講演論文集  24th-  489‐492  2015/11/12  [Not refereed][Not invited]
  
• 165 Topology Optimization of Rectenna for Energy Harvesters

  Mori Takuya, Igarashi Hajime  The Computational Mechanics Conference  2015-  (28)  "165  -1"-"165-2"  2015/10/10
• 162 Electromagnetic and Heat Conduction Analysis of Induction Heating Using Model Order Reduction

  Shimotani Toshihito, Sato Yuki, Igarashi Hajime, Hashimoto Eiji, Imanari Hiroyuki, Kihara Mirei  The Computational Mechanics Conference  2015-  (28)  "162  -1"-"162-2"  2015/10/10
• Acceleration of Motor Analysis Using Block Model Order Reduction

  下谷 俊人, 佐藤 佑樹, 五十嵐 一  電気学会研究会資料. RM  2015-  (126)  59  -64  2015/09/29
• Fast Analysis of Time-Periodic Eddy Current Problems Based on Time-Periodic Explicit Error Correction Method and Model Order Reduction

  佐藤 佑樹, 五十嵐 一  電気学会研究会資料. RM  2015-  (114)  55  -60  2015/09/28
• 電磁誘導型振動発電機と回路の結合系の数値シミュレーションおよび実験

  SUGISAWA TAKESHI, SATO TAKAHIRO, IGARASHI HAJIME  電磁力関連のダイナミックスシンポジウム講演論文集  27th-  449  -450  2015/05/14  [Not refereed][Not invited]
  
• Computational accuracy enhancement in magnetic field analysis by using orthogonalized infinite edge element method

  Kenta Tsuzaki, Yoshihiro Tawada, Shinji Wakao, Akihisa Kameari, Tadashi Tokumasu, Yasuhito Takahashi, Hajime Igarashi, Koji Fujiwara, Yoshiyuki Ishihara  Electrical Engineering in Japan (English translation of Denki Gakkai Ronbunshi)  191-  (1)  20  -28  2015/04/01  [Not refereed][Not invited]
   

  Electromagnetic phenomena intrinsically spread over an infinite region. Thus, effcient handling of open boundaries is one of the main issues in electromagnetic feld computations. This paper deals with the orthogonalized infinite edge element method that effciently performs precise analysis of the infinite region. In this method, several parameters are used to achieve high accuracy. As one of the parameters, we focus on the reference point and investigate the effect of its position setting on accuracy. We also evaluate the accuracy of the calculated magnetic feld in the far region. By applying boundary element method as postprocessing, it is found that high computational accuracy in the region can be effectively achieved.
• Comparison of Multi-Phase-Field and NGnet-based Topology Optimization Methods

  SATO TAKAHIRO, WATANABE KOTA, IGARASHI HAJIME  電気学会静止器研究会資料  SA-15-  (33-55)  63  -68  2015/03/05  [Not refereed][Not invited]
  
• Acceleration of Nonlinear Magneto-Quasi-Static Field Analysis Using Subdomain Model Order Reduction

  SATO YUKI, IGARASHI HAJIME, CLEMENS MARKUS  電気学会静止器研究会資料  SA-15-  (9-14.16-17.19-32)  25  -30  2015/03/05  [Not refereed][Not invited]
  
• Basic investigation of fast solver for optimization using finite element analysis

  WATANABE KOTA, TAIAMI YUKI, IGARASHI HAJIME  電気学会静止器研究会資料  SA-15-  (9-14.16-17.19-32)  7  -10  2015/03/05  [Not refereed][Not invited]
  
• Macroscopic magnetic properties considering eddy currents: analysis of fine conductive lines

  IGARASHI HAJIME, SATO YUKI, ITO YASUHISA  電気学会静止器研究会資料  SA-15-  (9-14.16-17.19-32)  111  -115  2015/03/05  [Not refereed][Not invited]
  
• フラクタル構造を有するチップレスRFIDタグの解析

  WATANABE YUTA, IGARASHI HAJIME  電気学会全国大会講演論文集(CD-ROM)  2015-  ROMBUNNO.1-023  2015/03/05  [Not refereed][Not invited]
  
• 倍電圧整流回路を接続した電磁誘導型振動発電の性能評価

  SUGISAWA TAKESHI, SATO TAKAHIRO, IGARASHI HAJIME  電気学会全国大会講演論文集(CD-ROM)  2015-  ROMBUNNO.3-117  2015/03/05  [Not refereed][Not invited]
  
• 強化学習を取り入れた免疫型アルゴリズムによる電磁機器の形状最適化

  WATANABE KOTA, IGARASHI HAJIME  MAGDAコンファレンス講演論文集  23rd-  237  -242  2014/12/04  [Not refereed][Not invited]
  
• 損失を考慮したシンクロナスリラクタンスモータのトポロジー最適化

  SATO SHUMPEI, SATO TAKAHIRO, FURUI SHINTARO, IGARASHI HAJIME  MAGDAコンファレンス講演論文集  23rd-  243  -246  2014/12/04  [Not refereed][Not invited]
  
• 誘電体レンズ装荷導波管平面アンテナのFDTD解析

  ITO KEIICHI, WATANABE KENTO, MIYATA KATSUMASA, IGARASHI HAJIME  MAGDAコンファレンス講演論文集  23rd-  55  -58  2014/12/04  [Not refereed][Not invited]
  
• パッシブ型無線温度センサの開発

  MURAKAMI RYO, IGARASHI HAJIME  MAGDAコンファレンス講演論文集  23rd-  483  -486  2014/12/04  [Not refereed][Not invited]
  
• 解析的手法および有限要素法を用いたリッツ線の特性解析

  AYA SOICHIRO, ITO YASUHISA, SATO YUKI, IGARASHI HAJIME  MAGDAコンファレンス講演論文集  23rd-  489  -490  2014/12/04  [Not refereed][Not invited]
  
• Coupled Analysis of Vibration Energy Harvester With Chaotic Oscillation Using Model Reduction

  Sato Takahiro, Sato Yuki, Igarashi Hajime  The Computational Mechanics Conference  2014-  (27)  110  -111  2014/11/22
• FE Analysis of Electromagnetic Devices Using Model Order Reduction Based on Proper Orthogonal Decomposition

  Shimotani Toshihito, Sato Yuki, Igarashi Hajime  The Computational Mechanics Conference  2014-  (27)  108  -109  2014/11/22
• Generation of Equivalent Circuits Using Model Order Reduction

  下谷 俊人, 佐藤 佑樹, 五十嵐 一  電気学会研究会資料. RM  2014-  (96)  1  -6  2014/09/26
• Macroscopic Magnetic Property of Soft Magnetic Composite Considering Eddy Currents

  五十嵐 一, 伊藤 泰久, 佐藤 孝洋, 河野 健二, 鈴木 理明  電気学会研究会資料. RM  2014-  (80)  55  -60  2014/09/25
• Multiobjective Topology Optimization of IPM Motor Based on NGnet

  佐藤 孝洋, 渡辺 浩太, 五十嵐 一  電気学会研究会資料. RM  2014-  (80)  49  -54  2014/09/25
• Topology Optimization Considering Multimaterial Distribution Using Normalized Gaussian Network

  佐藤 孝洋, 渡辺 浩太, 五十嵐 一  電気学会研究会資料. RM  2014-  (16)  1  -6  2014/01/24
• 2-D Electromagnetic Analysis with Natural Element Method

  信山 史明, 野口 聡, 五十嵐 一  電気学会研究会資料. RM  2014-  (1)  1  -4  2014/01/23
• 510 Topology Optimization of IPM motors Considering Stress Distributions

  SATO Takahiro, IGARASHI Hajime, WATANABE Kota  The Computational Mechanics Conference  2013-  (26)  "510  -1"-"510-2"  2013/11/02
• 503 Finite Element Analysis of Electromagnetic Field Using Proper Orthogonal Decomposition

  SATO Yuki, IGARASHI Hajime  The Computational Mechanics Conference  2013-  (26)  "503  -1"-"503-2"  2013/11/02
• 509 Multi-Objective Optimization of Electromagnetic Devices

  HIDAKA Yuki, IGARASHI Hajime  The Computational Mechanics Conference  2013-  (26)  "509  -1"-"509-2"  2013/11/02
• ON SUBDOMAIN MODEL ORDER REDUCTION FOR COMPUTATIONAL ELECTROMAGNETISM

  佐藤 佑樹, 五十嵐 一  計算数理工学論文集  13-  109  -114  2013/11
• Acceleration of Shape Optimization for Electromagnetic Devices Based on Model Order Reduction

  SATO YUKI, IGARASHI HAJIME  電気学会静止器研究会資料  SA-13-  (59-74)  35  -40  2013/09/26  [Not refereed][Not invited]
  
• A Topology Optimization method for Electric Machines Based on Normalized Gaussian Network

  SATO TAKAHIRO, WATANABE KOTA, IGARASHI HAJIME  電気学会静止器研究会資料  SA-13-  (59-74)  29  -34  2013/09/26  [Not refereed][Not invited]
  
• Basic Investigation on Numerical Simulation of Vibration Harvester based on Electromagnetic Induction

  SATO TAKAHIRO, WATANABE KOTA, IGARASHI HAJIME  電気学会静止器研究会資料  SA-13-  (15-28)  5  -10  2013/01/24  [Not refereed][Not invited]
  
• An optimization method based on genetic algorithm coupled with level-set method

  HIDAKA YUKI, IGARASHI HAJIME  電気学会静止器研究会資料  SA-13-  (1-14)  55  -60  2013/01/24  [Not refereed][Not invited]
  
• Hysteresis Modeling of Ferrite Material by using Micromagnetics

  UEHARA YUJI, FURUYA ATSUSHI, FUJISAKI JUN, SHIMIZU KOICHI, OSHIMA HIROTAKA, SUZUKI MICHIAKI, KAWANO KENJI, MIFUNE KEN, MATSUO TETSUJI, WATANABE KOTA, IGARASHI HAJIME  電気学会マグネティックス研究会資料  MAG-12-  (146-159)  39  -44  2012/12/06  [Not refereed][Not invited]
  
• 708 Analysis Using Nonconforming Voxel Finite Element Method and Its Applications

  Sato Takahiro, Watanabe Kota, Igarashi Hajime  The Computational Mechanics Conference  2012-  (25)  328  -329  2012/10/06
• Finite Element Analysis of Quasi Static Electromagnetic Fields Based on Model Reduction

  SATO Yuki, IGARASHI Hajime  電気学会研究会資料. RM, 回転機研究会  2012-  (94)  13  -18  2012/09/10
• Finite Element Analysis of Macroscopic Magnetic Properties of Soft Magnetic Composite

  ITO Yasuhisa, IGARASHI Hajime  電気学会研究会資料. RM, 回転機研究会  2012-  (114)  41  -44  2012/09/10
• Three Dimensional Shape Optimization of Inductors for High-Efficiency Boost Circuits

  SATO Takahiro, IGARASHI Hajime, WATANABE Kota, KAWANO Kenji, SUZUKI Michiaki, MATSUO Tetsuji, MIFUNE Ken, UEHARA Yuji, FURUYA Atsushi  電気学会研究会資料. SA, 静止器研究会  2012-  (79)  7  -12  2012/09/10  [Not refereed][Not invited]
  
• Three dimensional Parameter Optimization of Electro Magnetic Devices Using Nonconforming Voxel Finite Element Method

  佐藤 孝洋, 渡辺 浩太, 五十嵐 一  計算工学講演会論文集 Proceedings of the Conference on Computational Engineering and Science  17-  4p  2012/05
• Design optimization of RFID tag antenna loaded by integrated circuit

  渡部 雄太, 渡辺 浩太, 五十嵐 一  計算工学講演会論文集 Proceedings of the Conference on Computational Engineering and Science  17-  4p  2012/05
• Verification of Computational Accuracy in Magnetic Field Analysis by Infinite Edge Element Method

  TSUZAKI Kenta, TAWADA Yoshihiro, WAKAO Shinji, KAMEARI Akihisa, TOKUMASU Tadashi, TAKAHASHI Yasuhito, IGARASHI Hajime, FUJIWARA Koji, ISHIHARA Yoshiyuki  電気学会研究会資料. SA, 静止器研究会  2012-  (1)  7  -12  2012/01/26  [Not refereed][Not invited]
  
• A Study on Tetrahedral Mesh Quality Improvement by Partial Mesh Smoothing for Edge Finite Element Analysis

  TAKADA Atsushi, NOGUCHI So, IGARASHI Hajime, MIWA Masahiko  電気学会研究会資料. SA, 静止器研究会  2012-  (1)  13  -18  2012/01/26  [Not refereed][Not invited]
  
• Three-dimensional Shape Optimization of Inductors with Non-conforming Finite Element Method

  ITO Yasuhisa, IGARASHI Hajime, WATANABE Kota, IIJIMA Yosuke, KAWANO Kenji  電気学会研究会資料. SA, 静止器研究会  2012-  (23)  17  -22  2012/01/26  [Not refereed][Not invited]
  
• Three Dimensional Shape Optimization Using Nonconforming Voxel Finite Elements

  SATO Takahiro, WATANABE Kota, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2012-  (23)  23  -28  2012/01/26  [Not refereed][Not invited]
  
• A study of forgetfulness for the rational theorem in Profit Sharing reinforcement learning

  幸若 完壮, 渡辺 浩太, 五十嵐 一  ファジィシステムシンポジウム講演論文集  27-  1307  -1311  2011/09/12
• Frequency Domain Analysis of Antennas using Infinite Edge Element

  WATABABE Yuta, IGARASHI Hajime, KAMEARI Akihisa  電気学会研究会資料. SA, 静止器研究会  2011-  (46)  1  -4  2011/08/25  [Not refereed][Not invited]
  
• A High Efficiency Design of Electromagnetic Devices Using Evolutionary Optimization Methods

  SATO Takahiro, WATANABE Kota, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2011-  (46)  23  -28  2011/08/25  [Not refereed][Not invited]
  
• Orthogonalization, Deflation and Error Correction in Electromagnetic Field Analysis

  IGARASHI Hajime, WATANABE Yuta, ITO Yasuhisa  電気学会研究会資料. SA, 静止器研究会  2011-  (46)  85  -90  2011/08/25  [Not refereed][Not invited]
  
• A Study on Convergence Property of ICCG Method to Element Distortion (2)

  TAKADA Atsushi, NOGUCHI So, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2011-  (1)  25  -29  2011/01/20  [Not refereed][Not invited]
  
• Adaptive profit sharing reinforcement learning method for dynamic environment

  Sadamori Koujaku, Kota Watanabe, Hajime Igarashi  Proceedings - 10th International Conference on Machine Learning and Applications, ICMLA 2011  1-  462  -465  2011  [Not refereed][Not invited]
   

  In this paper, an Adaptive Forgettable Profit Sharing reinforcement learning method is introduced. This method enables agents to adapt the environmental changes very quickly. It can be used to learn the robust and effective actions in the uncertain environments which have the non-markov property, especially the partial observable markov process (POMDP). Profit Sharing learns rational policy that is easy to be learned and results in good behavior in POMDP. However, the policy becomes worse in the dynamic and huge environment that changes frequently and require the lots of actions to achieve the goal. In order to handle such kind of environment, the forgetting, which gives the adaptability and rationality to Profit Sharing, is implemented. This method allows the agent to forget past experiences that reduce the rationality of its policy. The usefulness of the proposed algorithm is demonstrated through the numerical examples. © 2011 IEEE.
• Double Antennas for Passive Long Range UHF-Band RFID,

  Proceedings of 15th international symposium on applied electromagnetics and mechanics  113  -114  2011  [Not refereed][Not invited]
  
• Non-conforming Finite Element Method with Tetrahedral Elements

  Proceedings of 15th international symposium on applied electromagnetics and mechanics  357  -358  2011  [Not refereed][Not invited]
  
• Three Dimensional Optimization Using the Voxel Based Finite Element Method with Homogenization

  Proceedings of 15th international symposium on applied electromagnetics and mechanics  351  -352  2011  [Not refereed][Not invited]
  
• Pareto optimization of antenna for passive UHF-band RFID

  Proceedings of 15th international symposium on applied electromagnetics and mechanics  209  -210  2011  [Not refereed][Not invited]
  
• Multi-Objective Topology Optimization Based on Immune Algorithm for Electromagnetic Devices

  Proc. 30th JSST Annual Conference  236  -241  2011  [Not refereed][Not invited]
  
• FDTD Analysis of Ultraviolet Waves Scattered from Dielectric Surfaces

  Proc. 30th JSST Annual Conference  166  -170  2011  [Not refereed][Not invited]
  
• Evolutional Design of Waveguide Slot Antenna with Dielectric Lenses

  Proceedings of COMPUMAG2011  CMP682  2011  [Not refereed][Not invited]
  
• Voxel Based Finite Element Method Using Homogenization

  Proceedings of COMPUMAG2011  CMP704  2011  [Not refereed][Not invited]
  
• Orthogonalized Infinite Edge Element Method ?Convergence Improvement by Orthogonalization of Hilbert Matrix in Infinite Edge Element Method

  Proceedings of COMPUMAG2011  CMP696  2011  [Not refereed][Not invited]
  
• On Error Correction Methods for Acceleration of Convergence

  Proceedings of COMPUMAG2011  CMP685  2011  [Not refereed][Not invited]
  
• Robust Optimization of IC Tag Antennas

  Proceedings of COMPUMAG2011  CMP686  2011  [Not refereed][Not invited]
  
• An Improvement of Convergence in Finite element Analysis with Infinite Element Using Deflation

  Proceedings of COMPUMAG2011  CMP787  2011  [Not refereed][Not invited]
  
• Accelerated FDTD computation applied to antenna shape

  Proceedings of COMPUMAG2011  CMP627  2011  [Not refereed][Not invited]
  
• Topology Optimization of UHF-band Antennas

  Proc. 14th IGTE Symposium  277  -282  2011  [Not refereed][Not invited]
  
• On Unphysical Solutions Obtained by Moment Method in Optimization of Wire Antennas

  Proc. 14th IGTE Symposium  44  -49  2011  [Not refereed][Not invited]
  
• 磁性部品の構造最適化設計手法についての研究 (第46回[日本電子材料技術協会]秋期講演大会--優秀賞受賞論文と受賞者の感想)

  飯島 洋祐, 河野 健二, 五十嵐 一  日本電子材料技術協会会報  41-  (0)  40  -42  2010/11  [Not refereed][Not invited]
  
• A Study on Convergence Characteristics of ICCG Method to Element Distortion

  TAKADA Atsushi, NOGUCHI So, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2010-  (76)  21  -26  2010/09/28  [Not refereed][Not invited]
  
• Projection matrices and subspace corrections in computational electromagnetism

  IGARASHI Hajime, WATANABE Kota  電気学会研究会資料. SA, 静止器研究会  2010-  (76)  65  -70  2010/09/28  [Not refereed][Not invited]
  
• Acceleration for FDTD Analysis of Electromagnetic Waves Coupled with Electric Circuit

  WATANABE Yuta, WATANABE Kota, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2010-  (76)  71  -76  2010/09/28  [Not refereed][Not invited]
  
• 北海道大学大学院情報科学研究科システム情報科学専攻 システム複合情報学研究室

  五十嵐 一  電気学会論文誌. A, 基礎・材料・共通部門誌 = The transactions of the Institute of Electrical Engineers of Japan. A, A publication of Fundamentals and Materials Society  130-  (2)  223  -223  2010/02/01  [Not refereed][Not invited]
  
• Electromagnetic Field Analysis for Eddy Current Testing of Railways

  YONETA Kenji, WATANABE Kota, ARAI Yuki, MIYAZAKI Yoshiki, NAGASHIMA Ken, IGARASHI Hajime  電気学会研究会資料. MAG, マグネティックス研究会  2010-  (26)  25  -29  2010/01/29  [Not refereed][Not invited]
  
• A Study on Smoothing Method for Automatic Hexahedral Mesh Generation

  MOTOOKA Yuichiro, NOGUCHI So, IGARASHI Hajime  電気学会研究会資料. MAG, マグネティックス研究会  2010-  (1)  13  -17  2010/01/28  [Not refereed][Not invited]
  
• Visualization of Electromagnetic Field Analysis Result with Volumetric Display

  INABA Tomoaki, NOGUCHI So, IGARASHI Hajime  電気学会研究会資料. MAG, マグネティックス研究会  2010-  (1)  19  -23  2010/01/28  [Not refereed][Not invited]
  
• On finite element analysis of eddy currents and their sensitivity using complex variables

  WATANABE Kota, IGARASHI Hajime  電気学会研究会資料. MAG, マグネティックス研究会  2010-  (1)  111  -116  2010/01/28  [Not refereed][Not invited]
  
• A genetic algorithm for combinational optimization problems with uncertainties

  Kenta Hoshino, Hajime Igarashi  Proceedings of the IEEE International Symposium on Computer-Aided Control System Design  368  -373  2010  [Refereed][Not invited]
   

  This paper describes a genetic algorithm (GA) applied to combinational optimization problems in which the objective functions include uncertain constant parameters. In the present method, noises whose probabilistic distribution is assumed based on the problem environments are added to the parameters during the evaluations process. It is assumed that this allows us to make approximate evaluation of the expected values of the objective function under uncertainties. It is shown that the present method results in the robust solutions, which have higher expectation values than the ones obtained by the conventional GA, to the traveling salesman and knapsack problems with uncertainties. © 2010 IEEE.
• Acquiring of walking behavior for four-legged robots using actor-critic method based on policy gradient

  R. Inoue, K. Watanabe, H. Igarashi  2010 IEEE INTERNATIONAL SYMPOSIUM ON INTELLIGENT CONTROL  795  -800  2010  [Refereed][Not invited]
   

  Actor-critic method based on policy gradient is an effective method for problems with high-dimensional learning space. In walking behavior of robots, the movement of robot's joint is cyclic. For this purpose, we apply closed-loops of B-spline curve to cyclic movement. Hence, we propose a method combined actor-critic method based on policy gradient with B-spline curve. In this method, B-spline curve uses for controlling target such as joints in robot on continuous space. By using B-spline curve, the target for control can move smoothly and flexible. In this paper, we applied this method to a four-legged robot with 12 joints and simulated on the Open Dynamics Engine (ODE) which is a dynamics simulation software. The simulation results show that robots succeeded in getting walking behavior.
• An Image Recognition Based on Neural Oscillator Network

  Kenta Hoshino, Hajime Igarashi  2010 INTERNATIONAL JOINT CONFERENCE ON NEURAL NETWORKS IJCNN 2010  780  -785  2010  [Refereed][Not invited]
   

  This paper introduces a novel image recognition method based on the neural oscillator network. In the present method, the dynamics of neurons is determined from neural coupling strengths relevant to the similarities in pixel levels, which have been used in the conventional image segmentation, as well as geometrical local features obtained from the Gabor filtering. Then the image regions under resultant neural synchronization are identified. It is shown that the accuracy of the present method, applied to the image recognition for pairs of identical and different alphabetical letters, is 76.9% and 62.2%, respectively. Moreover, the simple polygons are also correctly recognized by the present method.
• Acquisition of adaptive walking behaviors using machine learning with Central Pattern Generator

  T. Sato, K. Watanabe, H. Igarashi  2010 INTERNATIONAL JOINT CONFERENCE ON NEURAL NETWORKS IJCNN 2010  552  -559  2010  [Refereed][Not invited]
   

  Recently, biologically inspired approaches have received much attention for robot control. A typical example of them is control of rhythmic behaviors by Central Pattern Generator (CPG). However, this control has a problem that there are few theories to determine parameters of CPG. For this reason, they are determined experimentally. In this paper, we propose a combination method of Genetic Algorithm and Reinforcement Learning for determining parameters of CPG, and apply to a quadruped robot with the CPG controller. Simulation results show that the robot obtains walking behaviors automatically through learning process without using the parameters set by knowledge of designers.
• Multigrid method with adaptive IDR-based jacobi smoother

  Kota Watanabe, Seiji Fujino, Hajime Igarashi  Digests of the 2010 14th Biennial IEEE Conference on Electromagnetic Field Computation, CEFC 2010  1689  2010  [Not refereed][Not invited]
   

  The multigrid (MG) method is known as the fast linear solver for large scale finite element analyses. In the iterations of MG, the Gauss-Seidel method is usually adopted as the smoother. Recently, Induced Dimension Reduction (IDR)-based methods receive much attention because these methods solve faster than the other strong solvers such as BiCGStab method. In this paper, we present a performance of MG with adaptive IDR-based Smoother method. Numerical results show that the present method has good convergence and good parallel efficiency in the electromagnetic analyses. © 2010 IEEE.
• Deflation techniques for computational electromagnetism, Part I: Theoretical considerations

  Proc. of 14th Biennial IEEE Conference on Electromagnetic Field Computation (CD-ROM)  1458  2010  [Not refereed][Not invited]
  
• Deflation techniques for computational electromagnetism, Part II: Numerical applications

  Proc. of 14th Biennial IEEE Conference on Electromagnetic Field Computation (CD-ROM)  1459  2010  [Not refereed][Not invited]
  
• Evolutional design of small antennas for passive UHF-band RFID

  Hidetoshi Makimura, Yuta Watanabe, Kota Watanabe, Hajime Igarashi  Digests of the 2010 14th Biennial IEEE Conference on Electromagnetic Field Computation, CEFC 2010  1378  2010  [Not refereed][Not invited]
   

  This paper presents optimal design of antennas for passive IC tags used in UHF-band radio frequency identification. To improve the performance of IC tags, the shape of the meander line antennas and planar lattice antennas are optimized using the genetic algorithm. In the optimization process, the objective function includes the terms relevant to the antenna size, gain and input impedance. The characteristics of the antennas printed on a dielectric substrate are evaluated using the moment method. The optimization results in desirable input impedance for impedance matching and miniaturizing. © 2010 IEEE.
• Optimization of Meander Line Antenna Considering Coupling between Non-linear Circuit and Electromagnetic Waves for UHF-band RFID

  Proc. of 14th Biennial IEEE Conference on Electromagnetic Field Computation (CD-ROM)  1349  2010  [Not refereed][Not invited]
  
• 第19回MAGDAコンファレンス in 札幌 講演論文集

  日本AEM学会  2010  [Not refereed][Not invited]
  
• Study of optimization for inductor shape using probabilistic optimizing method

  Yosuke Iijima, Kenji Kawano, Hajime Igarashi, Kota Watanabe, Tetsuji Matsuo, Takeshi Mifune  Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy  56-  (10)  619  -624  2009/10  [Not refereed][Not invited]
   

  Recently, the inductor has become an important component in order to obtain high performance of the electric devices such as mobile telephone, and further improvement of the inductor performance is needed. Especially, the inductance under superimposed DC current is one of key properties for the application using inductor. However, it is difficult to satisfy such high performance only by an improvement of the magnetic material. Therefore it is required to establish the inductor shape design technique considering with the magnetic material properties in order to improve the inductor performance. In this paper, the shape optimization method of inductor using probabilistic optimize algorithm is discussed and the availability of this method is examined through the comparison between the calculation and the experiment. As a result, ̃ 60% downsized shape can be derived from this optimization method maintaining the same performance of the original inductor.
• Investigation on Topology Optimization of Electromagnetic Machines Using Stochastic Optimization Method

  WATANABE Kota, CAMPELO Felipe, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2009-  (54)  1  -4  2009/09/16  [Not refereed][Not invited]
  
• On Electromagnetic Field Analysis Based on Deflation

  IGARASHI Hajime, WATANABE Kota  電気学会研究会資料. SA, 静止器研究会  2009-  (54)  27  -32  2009/09/16  [Not refereed][Not invited]
  
• An Optimal Design of RFID in UHF Band

  MAKIMURA Hidetoshi, WATANABE Yuta, WATANABE Kota, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2009-  (54)  33  -36  2009/09/16  [Not refereed][Not invited]
  
• Effect of Quality of Hexahedral Mesh on FEA

  MOTOOKA Yuichiro, NOGUCHI So, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2009-  (54)  53  -58  2009/09/16  [Not refereed][Not invited]
  
• A Novel Reliability Analysis of Electromagnetic Devices by Using Kriging

  MARUYAMA Takayuki, IGARASHI Hajime  日本シミュレーション学会大会発表論文集 : シミュレーション・テクノロジー・コンファレンス・計算電気・電子工学シンポジウム  28-  (0)  345  -348  2009/06/11  [Not refereed][Not invited]
  
• Optimal Design of IC-tag Antenna using Moment Method

  MAKIMURA Hidetoshi, WATANABE Kota, WATANABE Yuta, IGARASHI Hajime  日本シミュレーション学会大会発表論文集 : シミュレーション・テクノロジー・コンファレンス・計算電気・電子工学シンポジウム  28-  (0)  349  -352  2009/06/11  [Not refereed][Not invited]
  
• RFID System Communication Analysis by FDTD Method

  WATANABE Yuta, WATANABE Kota, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2009-  (17)  1  -5  2009/01/30  [Not refereed][Not invited]
  
• Finite-Element Analysis of Antennas Based on Iterative Absorbing Boundary

  NAGATANI Atsuki, WATANABE Kota, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2009-  (17)  7  -10  2009/01/30  [Not refereed][Not invited]
  
• Simple Evaluation of Solution Accuracy on FEA by calculating Magnetic Flux Lines

  Proceedings of 17th International Conference on the Computation of Electromagnetic Fields  1062  -1063  2009  [Not refereed][Not invited]
  
• Visualization Method of Magnetic Flux Lines with Accurate Allocation Applying Tube System

  Proceedings of 17th International Conference on the Computation of Electromagnetic Fields  867  -868  2009  [Not refereed][Not invited]
  
• A Comparison of Parallel Finite Element Analysis Using Domain Decomposition

  Proceedings of 17th International Conference on the Computation of Electromagnetic Fields  837  -838  2009  [Not refereed][Not invited]
  
• Complex Adjoint Variable Method for Finite Element Analysis of Eddy Current Problems

  Proceedings of 17th International Conference on the Computation of Electromagnetic Fields  695  -696  2009  [Not refereed][Not invited]
  
• FDTD Analysis of UHF-band RFID for Metallic Objects

  Proceedings of 17th International Conference on the Computation of Electromagnetic Fields  476  -477  2009  [Not refereed][Not invited]
  
• Quality Evaluation of Automatically Generated Hexahedral Mesh for FEA

  Proceedings of 17th International Conference on the Computation of Electromagnetic Fields  406  -407  2009  [Not refereed][Not invited]
  
• Optimization of Inductors Using Evolutionary Algorithms and Its Experimental Validation

  Proceedings of 17th International Conference on the Computation of Electromagnetic Fields  324  -325  2009  [Not refereed][Not invited]
  
• FDTD Analysis of UHF-band RFID Considering Dielectric Effects

  Proceeding of 8th International Symposium on Electric and Magnetic Fields  CD-ROM OB1-2  2009  [Not refereed][Not invited]
  
• Optimization of Meander Line Antenna on Dielectric Substrate for UHF-band RFID

  Proceeding of 8th International Symposium on Electric and Magnetic Fields  CD-ROM A2-1  2009  [Not refereed][Not invited]
  
• A Robust Optimization Method Based on Adjoint Variable Method

  Proc. 8th International Symposium on Electric and Magnetic Fields  CD-ROM OB2-3  2009  [Not refereed][Not invited]
  
• Design of Conventiona lC-core Magnets Using a Multi-Step Optimization Procedure

  Proceedings of 17th International Conference on the Computation of Electromagnetic Fields  410  -411  2009  [Not refereed][Not invited]
  
• Application of Magnetic Flux Line Visualization from Hexahedral Edge Finite Element Analysis

  NOGUCHI So, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2008-  (49)  7  -12  2008/09/18  [Not refereed][Not invited]
  
• A Study on Enhancement of Mesh Quality by Moving Nodes and Smoothing for Automatic Hexahedral Mesh Generation

  MOTOOKA Yuichiro, NOGUCHI So, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2008-  (49)  13  -17  2008/09/18  [Not refereed][Not invited]
  
• A Study on the Convergence of Geometric Multigrid Method in Static Magnetic Filed Analysis

  WATANABE Kota, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2008-  (49)  67  -70  2008/09/18  [Not refereed][Not invited]
  
• A Novel Robust Optimization Method Based on Adjoint Variable Method

  MARUYAMA Takayuki, WATANABE Kota, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2008-  (49)  89  -92  2008/09/18  [Not refereed][Not invited]
  
• Stochastic Optimization of Inductor Shapes

  IGARASHI H, WATANABE W, MATSUO T, MIFUNE T, KAWANO K, IIJIMA Y  電気学会研究会資料. SA, 静止器研究会  2008-  (49)  93  -98  2008/09/18  [Not refereed][Not invited]
  
• On real-coded evolutionary methods of optimization of electromagnetic systems

  WATANABE Kota, MARUYAMA Takayuki, IGARASHI Hajime, MATSUO Tetuji, MIFUNE Takeshi  日本シミュレーション学会大会発表論文集 : シミュレーション・テクノロジー・コンファレンス・計算電気・電子工学シンポジウム  27-  (0)  47  -50  2008/06/19  [Not refereed][Not invited]
  
• Multiobective optimization using compromise programming and an immune algorithm

  Felipe Campelo, Frederico G. Guimaraes, Hajime Igarashi  IEEE TRANSACTIONS ON MAGNETICS  44-  (6)  982  -985  2008/06  [Not refereed][Not invited]
   

  The m-AINet is a modified version of the artificial immune network algorithm for single-objective and multimodal optimization (opt-AINet), with constraint-handling capability and improvements aiming to reduce the computational effort required by the original algorithm. In this paper we extend this algorithm for multiobjective problems by using the compromise programming approach to aggregate the objectives in the evaluation step. We adopt a compromise programming formulation that is theoretically able to map the whole Pareto front. The proposed multiobjective m-AINet is tested on the design of a loudspeaker with two objectives, showing promising results.
• Generating parametric design models using information from topology optimization

  Felipe Campelo, Satoru Ota, Kota Watanabe, Hajime Igarashi  IEEE TRANSACTIONS ON MAGNETICS  44-  (6)  986  -989  2008/06  [Not refereed][Not invited]
   

  A new hybrid methodology for the design of engineering devices is presented in this paper. This technique employs a topology optimization (TO) algorithm in order to obtain an initial design for a given device under consideration, followed by a parameterization routine which transforms the TO solution into a parametric model. Finally, this model is further optimized by means of a parametric optimization algorithm. The whole process is executed without any user intervention, and is able to deliver innovative solutions to problems in electromagnetic design. Results obtained on the design of a C-core magnet are shown in order to illustrate the applicability of the proposed method.
• An optimal configuration design method for HTS-SMES coils tanking account of thermal and electromagnetic characteristics

  So Noguchi, Youichi Inaba, Hajime Igarashi  IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY  18-  (2)  762  -765  2008/06  [Not refereed][Not invited]
   

  This paper describes an optimal design method for SMES coils wound with high temperature superconducting tapes. Commonly, on the design stage of a SMES coil, its configuration is optimized to reduce the winding' volume and the weight under taking into account the electromagnetic characteristics of high temperature superconducting tapes. The better configuration can be optimally designed to taken into account its thermal characteristics. So, we propose an optimal design method for SMES coils wound with Bi2223/Ag tape taking into account both electromagnetic and thermal characteristics. In this paper, the designs of 72 MJ toroidal SMES coil are investigated using the Simulated Annealing as an optimization method and the Finite Element Method as a thermal analysis method.
• Effective robust optimization based on genetic algorithm

  Takayuki Maruyama, Hajime Igarashi  IEEE TRANSACTIONS ON MAGNETICS  44-  (6)  990  -993  2008/06  [Not refereed][Not invited]
   

  Although probabilistic optimization methods based on genetic algorithm (GA) provides accurate results, its performance is sometimes considerably sensitive to parameter changes. Moreover, the constraints are violated due to such parameter changes. A robust GA which performs random perturbation during optimization processes has been applied to some mathematical problems to show that it works as fast as the usual GAs. An adequate elite reservation technique for the robust GA is presented and applied to the robust GA for electromagnetic problems. Moreover, this method is shown to find solutions which are kept feasible against parameter changes.
• Effect of preconditioning in edge-based finite-element method

  Hajime Igarashi, Nobito Yamamoto  IEEE TRANSACTIONS ON MAGNETICS  44-  (6)  942  -945  2008/06  [Not refereed][Not invited]
   

  This paper discusses mathematical properties of preconditioned finite-element matrices based on vector potential formulation (A method) and vector and scalar potential formulation (A-V method) for eddy-current problems. Numerical results show that A-V method with preconditioning is stable at all frequencies in contrast to A method. In this paper, this property is mathematically discussed by considering the diagonal scaling which is one of the simple preconditioning methods. In addition, regularization of A method is discussed.
• Research about the Accuracy of Magnetic Flux Line Computation from Hexahedral Edge Finite Element Analysis

  HIRAHATAKE Masashi, NOGUCHI So, IGARASHI Hajime  電気学会研究会資料. MAG, マグネティックス研究会  2008-  (13)  7  -12  2008/01/24  [Not refereed][Not invited]
  
• Robust Optimization Method for Electromagnetic Design with Constraints

  MARUYAMA Takayuki, IGARASHI Hajime  電気学会研究会資料. MAG, マグネティックス研究会  2008-  (13)  13  -18  2008/01/24  [Not refereed][Not invited]
  
• Robustness of Nested Multigrid Method for Edge-based Finite Element

  Proc. CEFC2008  PA1-18  2008  [Not refereed][Not invited]
  
• Hybrid Estimation of Distribution Algorithm Using Local Function Approximations

  Proc. CEFC2008  PF2-6  2008  [Not refereed][Not invited]
  
• A Spectral Topology Optimization Approach to the Design of Magnetic

  Proc. CEFC2008  PD3-18  2008  [Not refereed][Not invited]
  
• Allocation Method of Magnetic Flux Lines Applying Tube System for

  Proc. CEFC2008  PC1-19  2008  [Not refereed][Not invited]
  
• Finite-Difference Time-Domain Analysis of Waveguide Slot Antenna

  Proc. CEFC2008  OC2-3  2008  [Not refereed][Not invited]
  
• A Reliability Analysis of Electromagnetic Devices Using Surrogate Model

  Proc. CEFC2008  PB4-7  2008  [Not refereed][Not invited]
  
• On Uncertainty Analysis of Three-Dimensional Magnetostatic Systems

  Proc. CEFC2008  PC1-8  2008  [Not refereed][Not invited]
  
• 電磁界解析のアプローチと特徴

  シミュレーション学会誌  27-  (3)  140  -148  2008  [Not refereed][Not invited]
  
• Investigation of the characteristics of conformal microstrip antennas

  Ralf T. Jacobs, Arnulf Kost, Hajime Igarashi, Alan J. Sangster  COMPEL-THE INTERNATIONAL JOURNAL FOR COMPUTATION AND MATHEMATICS IN ELECTRICAL AND ELECTRONIC ENGINEERING  27-  (1)  110  -121  2008  [Not refereed][Not invited]
   

  Purpose - The purpose of this paper is the analysis of the radiation and impedance characteristics of cavity backed patch antennas embedded in a curved surface. Single patch elements and small scale array antennas are considered. The impact of curvature on the performance of the patch antenna is investigated, and the effect of mutual coupling between the elements in an array is examined. Design/methodology/approach - A finite element-boundary integral procedure has been implemented to accurately determine the performance characteristics of the patch radiators on planar and cylindrical surfaces. Simulated results will be shown to be in good agreement with measurements. Findings - Mutual coupling effects between array elements are examined and it can be observed that an active element primarily interacts with the nearest neighbour elements. A comparison of an array element with a single patch radiator shows that the mutual coupling effects cause no significant mismatch between a patch and a feed network in practical applications. Originality/value - The characteristics of conformal microstrip antennas are investigated for single patch radiators and patch elements in array environments. Simulations are supported by measurements.
• An effective robust genetic algorithm based on reduced evaluation

  Takayuki Maruyama, Hajime Igarashi  INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS  28-  (1-2)  177  -185  2008  [Not refereed][Not invited]
   

  Robust optimization searches for optimal solutions which remain feasible under the effect of uncertainties. The conventional robust optimization, however, often requires great computational cost to find robust solutions. This paper introduces a novel robust optimization method based on genetic algorithm. In this method, individuals with "good" performance are selected and tested for their robustness for reduction of computational time. It is shown that the present method works in shorter time in comparison with the conventional robust optimization.
• Topology optimization with smoothness considerations

  Felipe Campelo, Kota Watanabe, Hajime Igarashi  INTERNATIONAL JOURNAL OF APPLIED ELECTROMAGNETICS AND MECHANICS  28-  (1-2)  187  -192  2008  [Not refereed][Not invited]
   

  Topology optimization (TO) is a promising field for the design of industrial devices, since it can allow computational tools to develop creative solutions independently of initial topologies. However, the generation of smooth solutions, i.e., solutions that can be physically implemented, remains a challenge for most TO techniques available. In this paper, we discuss a set of operators that allow smoother topologies to be generated by an evolutionary topology optimization algorithm based on the artificial immune systems paradigm. The design of an electromagnetic device is used as a test case for the proposed methodology.
• 電磁界解析のための前処理付き並列クリロフ部分空間法

  計算数理工学論文集  239  2008  [Not refereed][Not invited]
  
• A Study on Parallel Computation Using Domain Decomposition and Krylov Subspace Methods

  WATANABE Kota, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2007-  (54)  21  -24  2007/09/20  [Not refereed][Not invited]
  
• Report on Compumag 2007 (the 16^ Conference on the Computation of Electromagnetic Fields)

  FUJIWARA Koji, KAMEARI Akihisa, WAKAO Shinji, TAKAHASHI Yasuhito, IGARASHI Hajime, MATSUO Tetsuji, IWASHITA Takeshi, MURAMATSU Kazuhiro, OKAMOTO Yoshifumi, YAMADA Takashi, KAWASE Yoshihiro, YAMAZAKI Katsumi, HIRATA Katsuhiro  電気学会研究会資料. SA, 静止器研究会  2007-  (54)  91  -97  2007/09/20  [Not refereed][Not invited]
  
• Optimal Design of Cylindrical Permanent Magnet Linear Motor

  KITAMURA Masashi, TAJIMA Fumio, AKAMI Yusuke, UCHIMI Noriyuki, LEE Tomoyuki, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2007-  (17)  69  -73  2007/01/26  [Not refereed][Not invited]
  
• Research on improving versatility of the automatic hexahedral mesh generation

  FUJIMORI Hirotomo, NOGUCHI So, IGARASHI Hajime, YAMASHITA Hideo  電気学会研究会資料. SA, 静止器研究会  2007-  (1)  13  -18  2007/01/25  [Not refereed][Not invited]
  
• Topology Optimization Using Immune Algorithm and Multigrid Method

  WATANABE Kota, CAMPELO Felipe, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2007-  (1)  19  -24  2007/01/25  [Not refereed][Not invited]
  
• Analytical calculation of magnetic flux line from hexahedral edge finite element analysis and its allocation using the bubble system for visualization

  Masashi Hirahatake, So Noguchi, Hajime Igarashi, Hideo Yamashita  IEEJ Transactions on Power and Energy  127-  (11)  12  -1212  2007  [Not refereed][Not invited]
   

  This paper presents analytical calculation of magnetic flux line from hexahedral edge finite element analysis and its allocation using the Bubble System for visualization. Most of methods to draw magnetic flux lines can't take their distribution into sufficient consideration. As a result, such visualizations bring out observer's misunderstanding about the magnetic field and the phenomenon. Therefore, the method to appropriately allocate the magnetic flux lines in a space using the Bubble System is proposed. In the proposed method, the bubble's radius of the Bubble System depends on the magnetic flux density to consider the density of lines. The proposed method using the Bubble System can visualize magnetic flux lines appropriately. Then, the observer can correctly grasp the magnetic field and the phenomenon. © 2007 The Institute of Electrical Engineers of Japan.
• Topology Optimization with Smoothness Considerations

  Proceedings of ISEM2007  303  2007  [Not refereed][Not invited]
  
• Reduction of Computational Time for Robust Geneteic Algorithm

  Proceedings of ISEM  301  2007  [Not refereed][Not invited]
  
• Generating Parametric Design Models Using Information from Multimodal Topology Optimization

  Proceedings of COMPUMAG2007  961  2007  [Not refereed][Not invited]
  
• An Effective Robust Optimization Based on Genetic Algorithm

  Proceedings of COMPUMAG2007  951  2007  [Not refereed][Not invited]
  
• Multiobjective Optimization Using Compromise Programming and an Immune Algorithm

  Proceedings of COMPUMAG2007  949  2007  [Not refereed][Not invited]
  
• Computation of the Scattering Parameters of a Slot Antenna using FE-BI/FMM

  Proceedings of COMPUMAG2007  507  2007  [Not refereed][Not invited]
  
• Allocation Method of Magnetic Flux Lines Using Bubble System for Magnetic Field Visualization

  Proceedings of COMPUMAG2007  81  2007  [Not refereed][Not invited]
  
• On effect of preconditioning in edge-based finite element method

  Proceedings of COMPUMAG2007  73  2007  [Not refereed][Not invited]
  
• 電磁界解析法の最近の動向

  電気学会誌  711  2007  [Not refereed][Not invited]
  
• A Parallel Preconditioned Conjugate Gradient Method for FEM

  Proceedings of COMPUMAG2007  71  2007  [Not refereed][Not invited]
  
• Transient Stability Analysis for LHD Superconductor

  NOGUCHI So, IGARASHI Hajime, ISHIYAMA Atsushi, YANAGI Nagato, IMAGAWA Shinsaku  低温工学・超電導学会講演概要集 = Meetings of Cryogenics and Superconductivity  75-  (0)  248  -248  2006/11/15  [Not refereed][Not invited]
  
• Visualization of Magnetic Flux Lines using the Bubble System

  HIRAHATAKE Masashi, NOGUCHI So, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2006-  (58)  7  -12  2006/08/24  [Not refereed][Not invited]
  
• A Basic Study on Parallel Computation of PCG Method Using Domain Decomposition

  WATANABE Kota, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2006-  (58)  25  -29  2006/08/24  [Not refereed][Not invited]
  
• On Effective Robust Optimization of Electromagnetic Systems

  MARUYAMA Takayuki, IGARASHI Hajime  The papers of Joint Technical Meeting on Static Apparatus and Rotating Machinery, IEE Japan  2006-  (58)  37  -42  2006/08/24  [Not refereed][Not invited]
  
• Numerical Analysis for Behavior of Magnetic Granular Material in Magnetic Field

  KURIBAYASHI Natsuki, IGARASHI Hajime, HONMA Toshihisa  電気学会研究会資料. SA, 静止器研究会  2006-  (16)  35  -42  2006/01/27  [Not refereed][Not invited]
  
• High-speed and large-scale computation in electromagnetic analysis

  KAMEARI AKIHISA, IGARASHI HAJIME, WAKAO SHINJI, NOGUCHI SO, IKEDA FUMIAKI, ISHIBASHI KAZUHISA, ENOKIZONO MASATO, ENDO HISASHI, OBA AKITO, KANAI YASUSHI, KANAYAMA HIROSHI, KAMITANI ATSUSHI, KAWAMOTO TADASHI, KUBO TAKEHARU, KEISHI TOMOHIRO, SHIMAZAKI MASAAKI, KAN KOJI, TSUBOI HAJIME, TOKUMASU TADASHI, TOKUYOSHI SHIN, NISHIGUCHI ISOHARU, HANO MITSUO, FUSAYASU HIROSHI, FUJIWARA KOJI, HONMA TOSHIHISA, MATSUDA TETSUYA, MATSUBARA YOSHIO, MURAMATSU KAZUHIRO, MIYATA KENJI, MORITA KATSUAKI, YAMASHITA HIDEO, O KOU, MATSUO TETSUJI, MIFUNE KEN, YAMADA TAKASHI, IWASHITA TAKESHI, SHIMADA SHIGEKI, OGAMI KOJI, HAMADA SHOJI, SESHIMA NORIO  電気学会技術報告  (1043)  120P  2006/01/05  [Not refereed][Not invited]
  
• 3D Topology Optimization Using an Immune Algorithm

  Proc. the 11th international IGTE symposium on numerical field calculation in electrical engineering  132  2006  [Not refereed][Not invited]
  
• On robustness of edge-based FE analysis using algebraic multigrid method

  Proc. the 11th international IGTE symposium on numerical field calculation in electrical engineering  90  2006  [Not refereed][Not invited]
  
• Automatic Generation of Robust Analogue Filters Using Genetic Algorithm

  Proc. 9th Workshop on Optimization and Inverse Problems in Electromagnetism  201  2006  [Not refereed][Not invited]
  
• Topology optimization based on immune algorithm and multi-grid method

  K. Watanabe, F. Campelo, H. Igarashi  12th Biennial IEEE Conference on Electromagnetic Field Computation, CEFC 2006  47  2006  [Not refereed][Not invited]
   

  This paper describes topology optimization of electromagnetic systems using the multi-grid method. The present topology optimization employs uniform rectangular finite elements, in which the multi-grid method effectively works as a fast linear solver. Moreover, the present method uses a new optimization algorithm, based on the artificial immune systems paradigm, in which multi-level search is carried out. ©2006 IEEE.
• Optimization of Cost Functions Using Evolutionary Algorithms With Local Learning and Local Search

  Proc. Twelfth Biennial IEEE Conference on Electromagnetic Field Computation  165  2006  [Not refereed][Not invited]
  
• Knowledge acquisition from optimization results of electromagnetic systems

  S. Ota, F. Campelo, H. Igarashi  12th Biennial IEEE Conference on Electromagnetic Field Computation, CEFC 2006  163  2006  [Not refereed][Not invited]
   

  This paper describes methods for acquisition of useful knowledge from optimization results of electromagnetic systems. Optimization of those systems on the basis of field computation often yields many quasi-optimal solutions which satisfy given criterion. In this study, such solutions are classified into clusters using the hierarchic method, principal component analysis and self-organizing map to extract useful knowledge for designers about them. ©2006 IEEE.
• An Automatic Hexhedral Mesh Generation to Control Shape of Elements

  Proc. Twelfth Biennial IEEE Conference on Electromagnetic Field Computation  53  2006  [Not refereed][Not invited]
  
• A parallel PCG method with overlapping domain decomposition

  K. Watanabe, H. Igarashi  12th Biennial IEEE Conference on Electromagnetic Field Computation, CEFC 2006  48  2006  [Not refereed][Not invited]
   

  This paper describes a liner solver for finite element analyses on parallel computers. The present method of parallel computation is based on the overlapping domain decomposition. This lead to the improvement of convergence as well as reduction of the communication cost between processor elements. The numerical results show that this method has good convergence in the eddy current analysis. © 2006 IEEE.
• A Topology Optimization Method Based on Immune Algorithm and Multi-Grid Method

  Proc. 9th Workshop on Optimization and Inverse Problems in Electromagnetism  187  2006  [Not refereed][Not invited]
  
• Transient Stability Analysis for LHD Superconductor Taking into Account Hall Effect

  KAWAWADA Nobuki, NOGUCHI So, IGARASHI Hajime, ISHIYAMA Atsushi, YANAGI Nagato, IMAGAWA Shinsaku  低温工学・超電導学会講演概要集 = Meetings of Cryogenics and Superconductivity  73-  (0)  33  -33  2005/11/21  [Not refereed][Not invited]
  
• 4005 On discrete forms of electromagnetic fields

  五十嵐 一  The Computational Mechanics Conference  2005-  (18)  643  -644  2005/11/17  [Not refereed][Not invited]
  
• Clustering of Optimal Solutions Using Self-Organizing Maps

  OTA Satoru, IGARASHI Hajime  日本シミュレーション学会大会発表論文集 : シミュレーション・テクノロジー・コンファレンス・計算電気・電子工学シンポジウム  24-  311  -314  2005/07/14
• A Study for Implementation of Reinforcement Learning on FPGA

  YAFUSO Yoshitaka, WATANABE Kota, MIYAZAKI Toshihiro, IGARASHI Hajime  日本シミュレーション学会大会発表論文集 : シミュレーション・テクノロジー・コンファレンス・計算電気・電子工学シンポジウム  24-  327  -330  2005/07/14
• 幾何マルチグリッド法の現状

  渡辺浩太, 野口聡, 五十嵐一  電気学会全国大会講演論文集  2005-  (5)  5.S11(5)-5.S11(8)  2005/03/17  [Not refereed][Not invited]
  
• 代数マルチグリッド法と幾何マルチグリッド法--電磁界解析への応用

  渡辺 浩太, 五十嵐 一  計算数理工学レビュー  2005-  (1)  1  -10  2005/03  [Not refereed][Not invited]
  
• An Immune Algorithm for Robust Optimization of Electromagnetical Devices

  CAMPELO Felipe, NOGUCHI So, IGARASHI Hajime  電気学会研究会資料. SA, 静止器研究会  2005-  (1)  51  -56  2005/01/27  [Not refereed][Not invited]
  
• An Analysis of Shielding against DC Magnetic Fields Generated by Electric Railways: Evaluation of Effective Permeability of Fine Structures

  Hiroshi Waki, Hajime Igarashi, Toshihisa Honma  IEEJ Transactions on Fundamentals and Materials  125-  (4)  309  -316  2005  [Not refereed][Not invited]
   

  This paper describes an effective analysis of magnetic shielding based on homogenization. The analyses become time-consuming if the problems include the magnetic substances having fine structure. The homogenization of the structure makes it possible to analyze effectively the magnetic fields. The authors introduce a method to estimate the effective permeability of the homogenized substance. This method can be applied to any periodic structure made of magnetic substance. The magnetic shielding effects by the structures against direct-current (DC) fields generated by electric railways are analyzed by using the present method. As a result, it is found that the overhead way and the protective fence near the railway work as a magnetic shield, whose effects can be improved by appropriate arrangement of those constructions. © 2005, The Institute of Electrical Engineers of Japan. All rights reserved.
• An Analysis of Magnetic Shielding Effect of Layered Shields Based on Homogenization

  Proc. COMPUMAG-2005  vol.3-  224  2005  [Not refereed][Not invited]
  
• Robust Optimization using the Real-coded Clonal Selection Algorithm

  Proc. COMPUMAG-2005  1-  58  -59  2005  [Not refereed][Not invited]
  
• Convergence of Geometric Multigrid Method for Electromagnetic Field Analysis

  ", Proc. 12th Int. Sympo. Interdisciplinary Electromagnetic, Mechanic and Biomedical Problems  444-445-445  2005  [Not refereed][Not invited]
  
• A Multi-Objective Proposal for the TEAM Benchmark Problem 22

  Proc. COMPUMAG-2005  vol.2-  270  2005  [Not refereed][Not invited]
  
• A Multigrid Method for Large Scale FE Analysis with Effective Memory Usage

  Proc. COMPUMAG-2005  vol.3-  82  2005  [Not refereed][Not invited]
  
• A Reduced Model for Finite Element Analysis of Steel Laminations

  Proc. COMPUMAG-2005  1-  6  -7  2005  [Not refereed][Not invited]
  
• Using Self-Organizing Maps for Decision Making in Multiobjective Optimization

  Proc. COMPUMAG-2005  vol.2-  62  2005  [Not refereed][Not invited]
  
• A Modified Immune Network Algorithm for Multimodal Electromagnetic Problems

  Proc. COMPUMAG-2005  vol.1-  60  2005  [Not refereed][Not invited]
  
• 8. 森林火災の延焼シミュレーション(<特集記事>大規模森林火災が及ぼす環境への影響)

  本間 利久, 上田 英典, 渡辺 浩太, 五十嵐 一, 福田 正己  自然災害科学  23-  (3)  344  -347  2004/11/30  [Not refereed][Not invited]
  
• (239)Survey of education systems of universities in the United States (Report No.2) : Summary of the survey of three universities ranked in top 5 in the US

  SHIMAZU Yoichiro, Ohnuki Somei, KOBAYASHI Yukinori, KANIE Shunji, IGARASHI Hajime  工学・工業教育研究講演会講演論文集  16-  473  -474  2004/07/30  [Not refereed][Not invited]
  
• Comparison of Algebraic Multigrid Methods in Large Scale FE Analysis

  WATANABE Kota, IGARASHI Hajime, HONMA Toshihisa  電気学会研究会資料. RM, 回転機研究会  2004-  (68)  13  -16  2004/07/08  [Not refereed][Not invited]
  
• An Analysis of Magnetic Shielding Using Homogenization Method

  WAKI Hiroshi, IGARASHI Hajime, HONMA Toshihisa  The Papers of Joint Technical Meeting on Static Apparatus and Rotating Machinery, IEE of Japan  2004-  (68)  61  -66  2004/07/08  [Not refereed][Not invited]
  
• Watanabe, K., Sato, K., Igarashi, H., Honma, T., "Post Processing for Large Scale Finite Element Analysis using Java Servlet and VRML", Computational Engineering I, JASCOME, 141-146 (2004)*

  2004  [Not refereed][Not invited]
  
• Igarashi, H., Yamamoto, A., Honma, T., "A Learnable Mesh Generation Technique Based on Genetic Algorithm", Computational Engineering I, JASCOME, 299-305 (2004)*

  2004  [Not refereed][Not invited]
  
• Watanabe, K., Igarashi, H., "On robustness of edge-based FE analysis using algebraic multigrid method", Proc. the 11th international IGTE symposium on numerical field calculation in electrical engineering, 90-95 (2004)*

  2004  [Not refereed][Not invited]
  
• Jacobs, R.T., Kost, A., Igarashi, H., Honma, T., Sangster, A.J., "Analysis of the Radiation Characteristics of Conformal Microstrip Antennas, Proc. 11th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC 2004), 280 (2004)*

  2004  [Not refereed][Not invited]
  
• Waki, H., Igarashi, H., Honma, T., "Estimation of Effective Permeability of Magnetic Composite Materials", Proc. 11th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC 2004), 86 (2004)*

  2004  [Not refereed][Not invited]
  
• Campelo, F., Guimareas, F.G., Saldanha, R.R., Takahashi, R.H.C., Igarashi, H., Noguchi, S., "A novel multiobjective immune algorithm using nondominated sorting", Proc. the 11th international IGTE symposium on numerical field calculation in electrical e・・・

  2004  [Not refereed][Not invited]
   

  Campelo, F., Guimareas, F.G., Saldanha, R.R., Takahashi, R.H.C., Igarashi, H., Noguchi, S., "A novel multiobjective immune algorithm using nondominated sorting", Proc. the 11th international IGTE symposium on numerical field calculation in electrical engineering, 308-313 (2004)*
• 「均質化手法による磁気シールドの解析」

  電気学会研究会資料  SA-04-55-  2004  [Not refereed][Not invited]
  
• Igarashi, H., Yamamoto, A., "A mesh generation method using machine learning based on genetic algorithm", Proc. the 11th international IGTE symposium on numerical field calculation in electrical engineering, 133-137 (2004)*

  2004  [Not refereed][Not invited]
  
• Waki, H., Igarashi, H., Honma, T., "An analysis of magnetic shielding against DC power lines based on homogenization", Proc. the 11th international IGTE symposium on numerical field calculation in electrical engineering, 272-275 (2004)*

  2004  [Not refereed][Not invited]
  
• Watanabe, K., Igarashi, H. Honma, T., "Comparison of Geometric and Algebraic Multigirid Methods in Edge-based FE Analysis", Proc. 11th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC 2004), 107 (2004)*

  2004  [Not refereed][Not invited]
  
• Waki, H., Igarashi, H., Honma, T., "Modeling of Reinforced Concrete Structures for Analysis of Environmental Magnetic Fields", Computational Engineering I, JASCOME, 117-124 (2004)*

  2004  [Not refereed][Not invited]
  
• Igarashi, H., "Visualization of Quasi-optimal Solutions in Stochastic Optimization", Proc. 11th Biennial IEEE Conference on Electromagnetic Field Computation (CEFC 2004), 398 (2004)*

  2004  [Not refereed][Not invited]
  
• 電磁界の有限要素解析における特異行列について (微分方程式の数値解法と線形計算)

  五十嵐 一, 本間 利久  数理解析研究所講究録  1320-  (0)  171  -178  2003/05  [Not refereed][Not invited]
  
• K. Watanabe, H. Igarashi and T. Honma: "Convergence of Multigrid Finite Element Method in Eddy Current Analysis", Proc. Applied Computational Electromagnetics Society (ACES) Conference, 775-778, (2003)*

  2003  [Not refereed][Not invited]
  
• Spectra of Finite Element Matrix for Magnetostatic and Quasi-static Electromagnetic Fields

  H. Igaras, T. Honma  Proc. Applied Computational Electromagnetics Society (ACES) Conference  779  -782  2003  [Not refereed][Not invited]
  
• K. Watanabe, H. Igarashi and T. Honma: Investigation of Parallel Multigrid Mathod Using Java Language, , COMPUMAG-Saratoga, Proc. vol.4, 34-35 (2003).*

  2003  [Not refereed][Not invited]
  
• H. Igarashi, K. Watanabe, T. Ito, T. Fukuda and T. Honma: A Finite Element Analysis of Surface Wave Plasmas, Proc. COMPUMAG-Saratoga, vol.4, 48-49 (2003)*

  2003  [Not refereed][Not invited]
  
• H. Igarashi, A. Yamamoto and T. Honma: Mesh Generation Based on Machine Learning, Proc. COMPUMAG-Saratoga, vol.1, 28-29 (2003)*

  2003  [Not refereed][Not invited]
  
• H. Igarashi, K. Ooi and T. Honma: Magnetostatic Permeability Tomography, Proc. COMPUMAG-Saratoga, vol.1, 126-127 (2003)*

  2003  [Not refereed][Not invited]
  
• Useful Formulas of Analytical Integration in Electromagnetic Field Computations (Part 1)

  WAKAO Shinji, IGARASHI Hajime, FUJIWARA Koji, KAMEARI Akihisa  電気学会研究会資料. RM, 回転機研究会  2002-  (58)  37  -42  2002/09/02  [Not refereed][Not invited]
  
• Application of Multigrid Method to Eddy Current Analysis by Finite Element Method

  WATANABE Kota, IGARASHI Hajime, HONMA Toshihisa  電気学会研究会資料. RM, 回転機研究会  2002-  (58)  49  -52  2002/09/02  [Not refereed][Not invited]
  
• Finite Element Analysis of Driven High-Frequency Problems : Convergence of ICCG method

  五十嵐 一, 福田 鉄平, 本間 利久  電気学会研究会資料. RM, 回転機研究会  2002-  (58)  77  -82  2002/09/02  [Not refereed][Not invited]
  
• Diagnosis of structural materials based on computational electromagnetism and inverse analysis

  五十嵐 一, 大井 健太郎, 本間 利久  電気学会研究会資料. RM, 回転機研究会  2002-  (58)  95  -100  2002/09/02  [Not refereed][Not invited]
  
• 電磁界解析におけるマルチグリッド法の有限要素法への適用について (産業上の非線形問題と数値シミュレーションと領域分割法)

  渡辺 浩太, 五十嵐 一, 本間 利久  数理解析研究所講究録  1288-  (0)  115  -121  2002/09  [Not refereed][Not invited]
  
• 「表面波プロセスプラズマのFDTD解析」<平成14年度電気関係学会北海道支部連合大会，北見>

  2002  [Not refereed][Not invited]
  
• 「フライホイールにおける渦電流場の有限要素解析」<平成14年度電気関係学会北海道支部連合大会，北見>

  2002  [Not refereed][Not invited]
  
• 「2次辺要素を用いた有限要素行列の条件数について」<平成14年度電気関係学会北海道支部連合大会，北見>

  2002  [Not refereed][Not invited]
  
• "計算電磁気学と逆問題手法による構造材の欠陥診断"

  電気学会静止器回転機合同研究会  SA-02-38-  RM-02-74  2002  [Not refereed][Not invited]
  
• "電磁界数値解析で役立つ解析積分公式集(その1)"

  電気学会静止器回転機合同研究会  SA-02-28-  RM-02-64  2002  [Not refereed][Not invited]
  
• 3次元静磁場有限要素法解析におけるマルチグリッド法のメッシュ依存性について

  第14回電磁力のダイナミクスシンポジウム講演論文集  93  -96  2002  [Not refereed][Not invited]
  
• "駆動源のある高周波問題の有限要素解析-ICCGの収束性-"

  電気学会静止器回転機合同研究会  SA-02-35-  RM-02-71  2002  [Not refereed][Not invited]
  
• Igarashi, H. and Honma, T.:"Convergence of Conjugate Gradient Method Applied to Driven Microwave Problems", Proc. CEFC-Perugia, 265(2002)*

  2002  [Not refereed][Not invited]
  
• 電磁場の有限要素解析におけるICCGの収束性

  第51回理論応用力学講演会講演論文集  621  -622  2002  [Not refereed][Not invited]
  
• 「静磁界による材料中の透磁率の同定」<平成14年度電気関係学会北海道支部連合大会，北見>

  2002  [Not refereed][Not invited]
  
• 「磁気ヘッドのアダプティブ有限要素解析」<平成14年度電気関係学会北海道支部連合大会，北見>

  2002  [Not refereed][Not invited]
  
• Javaを用いたプラズマ粒子シミュレーション

  第14回電磁力のダイナミクスシンポジウム講演論文集  97  -100  2002  [Not refereed][Not invited]
  
• "電磁界解析におけるマルチグリッド法の有限要素法への適用について"

  渡辺 浩太, 五十嵐 一, 本間 利久  京都大学数理解析研究所講究録1288  1288-  115  -121  2002  [Not refereed][Not invited]
  
• 電磁界解析におけるマルチグリッド法の有限要素法への適用について

  115  -121  2002  [Not refereed][Not invited]
  
• 高周波電磁界解析における有限要素行列のスペクトル

  平成14年電気学会全国大会  3-  (26-29/)  5  -165  2002  [Not refereed][Not invited]
  
• "マルチグリッド法を用いた有限要素法の渦電流解析への適用"

  電気学会静止器回転機合同研究会  SA-02-30-  RM-02-66  2002  [Not refereed][Not invited]
  
• Watanabe, K., Igarashi, H. and Honma, T.:"Convergence of Multigrid Method for Edge-based FEM", Proc. CEFC-Perugia, 76(2002)*

  2002  [Not refereed][Not invited]
  
• 「格子ガスオートマトン法による流体解析」<平成13年度電気関係学会北海道支部連合大会，札幌>

  2001  [Not refereed][Not invited]
  
• 「Pulsed Plasma Thruster(PPT)における電流層の数値シミュレーション」<平成13年度電気関係学会北海道支部連合大会，札幌>

  2001  [Not refereed][Not invited]
  
• 「要素形状によるマルチグリッド法の収束性に関する検討」<平成13年度電気関係学会北海道支部連合大会，札幌>

  2001  [Not refereed][Not invited]
  
• 「電磁粒子シミュレーションによる ビームプラズマ不安定性に関する研究」<平成13年度電気関係学会北海道支部連合大会，札幌>

  2001  [Not refereed][Not invited]
  
• 「PPT(パルス型プラズマスラスタ)プラズマの1次元解析」<平成13年度電気関係学会北海道支部連合大会，札幌>

  2001  [Not refereed][Not invited]
  
• Igarashi, H. and Honma T., "On the Convergence of ICCG Applied to Finite Element Equation for Quasi-Static Fields", Proc. COMPUMAG-Evian, II, 204-205 (2001)*

  2001  [Not refereed][Not invited]
  
• Igarashi, H., "On Identification of Magnetic Sources in Materials", Proc. ISIP2001, 202 (2001)*

  2001  [Not refereed][Not invited]
  
• 「電磁鋼板の磁区解析‐基礎検討‐」

  電気学会研究会資料  MAG-01-226-  2001  [Not refereed][Not invited]
  
• 「簡易モデルによるPPT(Pulsed Plasma Thruster)の解析」<原子力学会北海道支部第19回研究発表講演会，札幌>

  2001  [Not refereed][Not invited]
  
• 「電気的テザーシステムの性能解析」<平成13年度電気関係学会北海道支部連合大会，札幌>

  2001  [Not refereed][Not invited]
  
• 「有限要素法におけるマルチグリッド法の収束性について」

  電気学会研究会資料  SA-01-9-  (RM-01-77)  2001  [Not refereed][Not invited]
  
• 「渦電流解析における有限要素法の性質について」

  電気学会研究会資料  SA-01-07-  (RM-01-75)  2001  [Not refereed][Not invited]
  
• 「マルチグリッド法を用いたFEMによる3次元静磁場検証モデルの解析」<平成13年度電気関係学会北海道支部連合大会，札幌>

  2001  [Not refereed][Not invited]
  
• 「超伝導テープ線材の微視的解析」<平成13年度電気関係学会北海道支部連合大会，札幌>

  2001  [Not refereed][Not invited]
  
• Igarashi, H. and Honma, T., "Property of Second Order Edge Elements in a Class", Proc. ISEM-Tokyo, 243-244 (2001)*

  2001  [Not refereed][Not invited]
  
• Igarashi, H., Kost, A. and Honma, T., "Reconstruction of Planar Magnetic Charge Distribution, Proc. ISEM-Tokyo, 621-622 (2001)*

  2001  [Not refereed][Not invited]
  
• Igarashi, H. and Honma T., "A Direct Reconstruction of Magnetic Charge for Non-Destructive Testing", Proc. ENDE, 47-48 (2001)*

  2001  [Not refereed][Not invited]
  
• Investigation of FE-BE Coupled Nonlinear Magnetostatic Field Analysis Using Edge Element

  WATANABE Kouta, IGARASHI Hajime, HONMA Toshihisa  電気学会基礎・材料・共通部門大会講演論文集 = Proceeding of Annual Conference of Fundamentals and Materials Society, IEE Japan  2000-  (0)  368  -368  2000/09/07  [Not refereed][Not invited]
  
• 辺要素有限要素行列の基本性質-ゲージ, 退化次数, 固有値と条件数-

  五十嵐一  電気学会静止器・回転機合同研資  2000
• An Inverse Analysis of Permanent Magnets in Motors

  H. Igarashi, A. Kost, T. Honma  Digest of the 9th Biennial IEEE Conference of Electromagnetic Field Computation-CEFC2000  445  2000  [Not refereed][Not invited]
  
• Bastos, J.A., Kost, A., Jaenicke, L., Sadowski, N. and Igarashi, H. :"Using Very Flat Finite Elements for Plate Shielding Considering Nonlinearity", Proc. ICEF2000: 55-58 (2000)

  2000  [Not refereed][Not invited]
  
• Igarashi, H.: "On the Property of the Curl-Curl matrix in Finite Element Analysis with Edge Elements", Digest of the 9th Biennial IEEE Conference of Electromagnetic Field Computation-CEFC: 81 (2000)*

  2000  [Not refereed][Not invited]
  
• Igarashi, H.:"Finite Elements, Circuit Theory and Homology", Proc. JSST2000 Int. Conf. on Modeling, Control and Computation in Simulation: 35-38 (2000)

  2000  [Not refereed][Not invited]
  
• Mathematical Models of Magnetic Materials and Computational Electromagnetism

  IGARASHI Hajime  Journal of the Society of Materials Science, Japan  48-  (10)  1214  -1215  1999/10/15
• Numerical Simulation of Two-Dimensional Quantum Waves in Magnetic Field

  IGARASHI Hajime, HONMA Toshihisa, YOSHIKAWA Tomoyuki  シンポジウム電磁力関連のダイナミックス講演論文集  11-  (0)  313  -315  1999/10/13  [Not refereed][Not invited]
  
• An Inverse Inference of Spatial Distribution of Permanent Magnetization

  IGARASHI Hajime  電気学会研究会資料. RM, 回転機研究会  1999-  (55)  43  -48  1999/08/19
• Kost, A. and Igarashi, H. : "Different Numerical Methods for Electromagnetic Field Computation with Thin Shielding Sheets", Proc. IEEE Int. Symposium on Electromagnetic Compatibility, 248-253 (1997)＊

  1997  [Not refereed][Not invited]
  
• 境界要素法解析における疑似特異性の正則化 : 3次元ポテンシャル場の場合

  渡辺 浩太, 五十嵐 一, 本間 利久  電気学会研究会資料. RM, 回転機研究会  1995-  (63)  1  -10  1995/08/29  [Not refereed][Not invited]
  
• An Analysis of Plasma Sheath by Boundary Element Method

  TSUBOTA Keisuke, IGARASHI Hajime, HONMA Toshihisa  電気学会研究会資料. RM, 回転機研究会  1995-  (63)  11  -20  1995/08/29  [Not refereed][Not invited]
  
• 軸対称3次元問題の境界要素法解析(自由境界問題の数値解析とその周辺)

  本間 利久, 五十嵐 一, 槌本 昌則  数理解析研究所講究録  744-  (0)  239  -247  1991/02  [Not refereed][Not invited]
  

Books etc

• Topology optimization and AI‐based design of power electronic and electrical devices : principles and methods

  五十嵐, 一 (Single work)
  Academic Press 2024/02 (ISBN: 0323991661) 382
• 電磁界解析による最適設計：トポロジー最適化の基礎から機械学習まで

  五十嵐 一 
  森北出版 2023/03 (ISBN: 4627787715) 352
• Compendium on Electromagnetic Analysis: vol.3 Antennas, antenna arrays and microwave devices

  (ContributorChapter 8)
  World Scientific 2020/08
• Compendium on Electromagnetic Analysis: vol.2 The new generation of electric machines

  (ContributorChapter 2)
  World Scientific 2020/08
• シミュレーション辞典

  五十嵐 一 (Contributor)
  2012
• Computational Engineering I

  JASCOME 2004
• 新しい計算電磁気学―基礎と数理

  五十嵐 一, 加川 幸雄, アラン ボサビ, 亀有 昭久, 西口 磯春, Alain Bossavit (Joint work)
  培風館 2003/12 (ISBN: 4563067318) 295

  
• 数値電磁力学―基礎と応用 (計算電気・電子工学シリーズ (14))

  本間 利久, 五十嵐 一, 川口 秀樹 (Joint work)
  森北出版 2002/07 (ISBN: 4627716419) 251

  

Presentations

• 深層学習によるモータトポロジー最適化の高速化  [Invited]

  佐々木秀徳, 五十嵐一

  電気学会全国大会  2023/03
• モンテカルロ木探索を用いた最適設計  [Invited]

  佐藤駿輔, 五十嵐一

  電気学会全国大会  2023/03
• AI技術のモータ設計開発への応用  [Invited]

  五十嵐一

  電気学会全国大会  2023/03
• 電気電子機器のトポロジー最適化とAIによる最適設計  [Invited]

  五十嵐一

  システム制御情報学会セミナー2022  2022/11
• トポロジー最適化・機械学習を用いた最適設計  [Invited]

  五十嵐一

  モータ技術シンポジウム  2022/07
• Optimal Design of Electric Devices Based on Machine Learning  [Invited]

  Hajime Igarashi

  ISEM2022，Greece  2022/06
• 深層学習を用いた回転機磁気構造のトポロジー最適化技術  [Invited]

  佐々木, 五十嵐

  電子情報通信学会 総合大会  2022/03
• Optimal and automatic design of electric apparatus using machine learning  [Invited]

  Hajime Igarashi

  第3回インサイト・データサイエンスカンファレンス  2021/08
• Topology optimization of electric apparatus and automatic design using AI  [Invited]

  Hajime Igarashi

  Techno-Frontier 2021  2021/06
• Design technology based on topology optimization, deep learning and machine learning  [Invited]

  Hajime Igarashi

  サイエンス&テクノロジーセミナー  2021/04
• Application of deep learning and topology optimization to magnetic circuit design of electric motors  [Invited]

  Hajime Igarashi

  自動車技術会モータ技術部門委員会  2021/01
• Vibration energy harvester using electromagnetic induction  [Invited]

  Hajime Igarashi

  2020 年度 第 3 回 EH コンソーシアム 総会  2020/12
• AI Technology with Aid of Data-Driven Method Makes EM Simulation and Optimization More Effective  [Invited]

  Hajime Igarashi

  JMAG Users Conference 2020  2020/12
• Analysis and optimal design of electric apparatus using AI technology and big data  [Invited]

  Hajime Igarashi

  Panasonic総合技術シンポジウム 専門技術セッション  2020/11
• Data-driven methods for computational electromagnetism  [Invited]

  Hajime Igarashi

  International Symposium on Numerical Modeling towards Digital Twin in Electrical Engineering  2020/01
• 環境発電デバイスの発電効率を最適設計により向上させる技術を開発  [Not invited]

  五十嵐 一

  日本経済新聞  2019/07
• トポロジー最適化の基礎と応用およびAI技術の適用  [Invited]

  五十嵐 一

  サイエンス&テクノロジー社セミナー  2019/03
• 北大と明電舎，EV用モーターをAIで最適設計  [Not invited]

  五十嵐 一

  日本経済新聞社  2018/11
• Topology Optimization Based on Deep Learning and toward Their Coevolution  [Invited]

  IGARASHI HAJIME

  JSST2018  2018/09
• トポロジー最適化を用いたマイクロ波エネルギーハーベスタの開発  [Invited]

  五十嵐 一

  第51回野依フォーラム  2018/04
• AI技術と高精度電磁界解析を用いた最適設計  [Invited]

  五十嵐一, 佐々木秀徳

  平成30年電気学会全国大会シンポジウム講演  2018/03
• 遺伝的アルゴリズム を用いた電気機器 の最適設計  [Invited]

  五十嵐 一

  精密工学会「基礎講座 トポロジー最適化 －設計を変える！」」  2017/10
• 電磁界解析による最適設計技術  [Invited]

  五十嵐 一

  エレクトロニクス実装学会サマーセミナー  2017/08
• Model Order Reduction, Homogenization and Their Combination  [Invited]

  IGARASHI HAJIME

  COMPUMAG2017  2017/06
• マルチスケール問題の電磁界解析：均質化とモデル縮約法  [Invited]

  五十嵐 一

  平成28年度磁性流体連合講演会  2016/12
• モータ回転子・固定子のトポロジー最適化  [Invited]

  五十嵐 一

  第36回モータ技術シンポジウム  2016/04
• IPMモータのトポロジー最適化とその実験的検証  [Invited]

  五十嵐 一

  電気学会第25回電磁界解析に関するセミナー  2015/12
• 電磁界解析を用いた最適設計  [Invited]

  五十嵐 一

  JMAGユーザ会2015  2015/12
• 進化計算を用いた最適化デザイン  [Invited]

  五十嵐 一

  電子情報通信学会信越支部講演会  2015/10
• Macroscopic magnetic property of soft magnetic composite considering eddy current losses  [Invited]

  IGARASHI HAJIME

  日本ボンド磁性材料協会2014年例会  2014/09
• 電磁界解析による最適設計技術  [Invited]

  五十嵐 一

  平成25年度電気学会電子・情報・システム部門大会 先端技術セミナー  2013/09

Association Memberships

• 日本シミュレーション学会   日本AEM学会   電子情報通信学会   電気学会   International COMPUMAG Society   IEEE   計算数理工学会   

Research Projects

• Generation of new three-dimensional structure of permanent magnet motors using topology optimization

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2021/04 -2024/03 

  Author : 五十嵐 一

   

  トポロジー最適化は，寸法や位置などの形状パラメータを事前に設定して最適化するパラメータ最適化とは異なり，穴の生成・消滅を含めて自由に物体を変形して，最適形状を探査する．このため，設計者の想定を超える斬新な構造を得ることができる．このような背景から，産業的に重要な永久磁石モータのトポロジー最適化に関する研究が世界的に行われてきた．しかし，これまでのトポロジー最適化では，モータの断面形状のみを考えていたため，モータの3次元的な最適構造を見出すことができなかった． 本研究では，永久磁石モータの最適設計法を大きく拡張し，鉄心のみならず永久磁石の形状と配向を自由変化させるとともに，モータ軸方向への構造変化を包含する3次元トポロジー最適化を実現する．本研究により，電気自動車などに使用される薄型モータの性能向上を実現とするとともに，たとえば軸方向に回転子が磁石埋め込み型から表面磁石型に変化するような，全く新しいモータ3次元構造の獲得と，それによるモータ性能の飛躍的向上を目指す．さらに本最適化法を設計現場で活用可能にするため，3次元深層学習による高速化を実現する． 本年度は，上記目的のために次の研究を実施した．(1)パラメータ最適化とトポロジー最適化を同時に実行する新しい最適化手法を開発した．(2)トポロジー最適化を高速に実施するために，モータ構造からトルク特性を予測する深層学習機を開発した．さらにこの深層学習機による推定の根拠を理解するために，注目領域を可視化する方法を検討した．(3)永久磁石モータのトポロジー最適化の探索性能を改善するために，ガボールフィルタを基底関数として形状を表現する新しい方法を開発した．(4)モータの多材料トポロジー最適化を高速化するために，深層学習機による特性推定法を開発した．これらの研究成果を国際学術雑誌に論文として発表した．
• トポロジー最適化と深層学習の共進化による回転機の高速最適設計の実現

  日本学術振興会：科学研究費補助金 挑戦的研究(萌芽)

  Date (from‐to) : 2018/04 -2021/03 

  Author : 五十嵐 一
• ハルバッハアレー振動発電機によるインフラ構造物状態モニタリングの実現

  日本学術振興会：科学研究費補助金(基盤研究(B))

  Date (from‐to) : 2018/04 -2021/03 

  Author : 五十嵐 一
• Wide-band chaotic vibration harvester for safety surveillance of infrastrucrure

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2015 -2017 

  Author : Igarashi Hajime, KANIE Shunji

   

  In this study, we have developed a wireless sensor for monitoring of heath condition of infrastructures such as bridges, tunnels and transmission line towers. To realize the wireless sensor which works without batteries, we have developed a novel chaotic-vibration energy harvester which can harvest powers from the vibration of the infrastructures with wideband spectrum. It is experimentally shown that the energy harvester can drive the wireless sensor from the excited vibration whose amplitude is about 0.1G.
• モデル縮約による電磁機器の高速3次元最適化の実現

  日本学術振興会：科学研究費補助金 挑戦的萌芽研究

  Date (from‐to) : 2013/04 -2016/03 

  Author : 五十嵐 一
• 環境電磁波のエネルギーで動作する無線センサの開発

  JSPS：International Joint Research Project

  Date (from‐to) : 2013/04 -2015/03 

  Author : IGARASHI HAJIME
• 社会インフラの遠隔安全監視を行う振動発電式セミパッシブ無線センサ

  日本学術振興会：科学研究費補助金 基盤研究(B)

  Date (from‐to) : 2012/04 -2015/03 

  Author : 五十嵐一
• インフラ安全監視を行う無電源作動ワイヤレスセンサー

  日本学術振興会：科学研究費補助金 基盤研究(C)

  Date (from‐to) : 2009 -2011 

  Author : 五十嵐 一
• 発見的最適形状アルゴリズムを用いたインダクタ設計技術の構築

  JST：JST A-STEP

  Date (from‐to) : 2007/07 -2008/06 

  Author : IGARASHI HAJIME
• Development of the system to prevent the forest fire expansion in Siberia by field simulation informatics

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2004 -2006 

  Author : HONMA Toshihisa, KISHINAMI Takeshi, FUKUDA Masami, IGARASHI Hajime, WATANABE Kouta, KIMURA Keiji

   

  We made 5 subgroups of a) to e) and studied forward with changing the information: a) Fire Detection: We tried to make a method to change the parameters by each area and season to detect false alarms, and we tried to improve the detection rate. And we made a new method of fire detection with the edge of the smoke in order to detect small fires. b) Classification Vegetation We classified the vegetation from NOAA and MODIS imagery. We also analyzed the observed data by fire service and validated the vegetation classification. c) Database of Maps and Fire History: We analyzed the severely and activity of the forest fire with the data of the fire service. As a result, one of the main factors is the dead woods on the ground in the forest. d) Fire Expansion Simulation We built the forest fire expansion simulation about weather which makes the great effect to the fire behavior. We are incorporating the regional meteorological simulation into the forest fire expansion simulation. As a result, the adjusting rate grew better. e) Next Age GIS We charged the groups from a) to d). The results of the forest fire simulation were visualized. We are preparing to publish the information which fire fighters need thorough internet. We contributed many study and helps to the fire fighters with remote sensing technology and the ground truth.
• Study on machine learning for generation of finite element models of electrical machines

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 2003 -2005 

  Author : IGARASHI Hajime, NOGUCHI So, WATANABE Kota

   

  In this research, we have developed a new method to realize automatic generation of finite element meshes for electric machines. In this method, an initial course mesh is prepared, and element properties P are computed where P is a linear combination of element features such as magnitude of magnetic induction at the element, distance from the nearest corner of magnetic material, distance from the nearest current source and so on. The element with largest P is subdivided into two finer elements. And this process is repeated until the number of elements equals a prescribed number. The error in the finite element analysis on the obtained mesh is then computed. This error strongly depends on the mesh quality, which is dependent on the weights in the linear combination of the element features. We optimize the weights using the genetic algorithm. When the weights are optimized, this method can be applied for other similar finite element models of electrical machines. It is shown that the resultant finite element mesh using the above method, called the simple method, often have flat elements which are inadequate for finite element analysis. To resolve this difficulty, we introduce mesh control techniques so that the number of subdivision of element edges is determined from their length and a criterion to choose elements to be subdivided. The finite element meshes obtained using this method, called the mesh control method, are shown to be better than those obtained using the simple method. Although the mesh quality is improved by the mesh control method, it becomes worse when the initial course mesh includes flat elements. It is difficult to overcome this problem as long as the mesh is generated from the initial mesh. For this reason, we introduce another method where the density of nodes is determined using the above mentioned machine learning, and elements are generated using the Delaunay triangulation on the basis of the nodes obtained above. This method is shown to improve the mesh quality.
• ELECTROMAGNETIC MESOSCOPIC MODEL IN CONTINUOUS MEDIA

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 1995 -1997 

  Author : HONMA Toshihisa, MAGOS A, IVANYI A, JAKAB L, DEAK P, RICHTER P

   

  From 1995 to 1998, we studied on mesoscopic phenomena from view point of experimental and numerical aspect and considered its engineering application. Results are summarized as follows, (1) FLR (finite Larmor radius) - MHD (magnetohydrodynamics) model and gyro-fluid model are applied to understand the mechanism of the Landau damping and resonance between electromagnetic waves and particles in mesoscopic plasmas. In addition, super particle models are used to simulate an ion-electron two - stream instability with a parallel computer and MHD models are applied to study on a stability for tokamak plasmas with the negative shear. (2) We solved the Landau - Lifshitz - Gilbert equation for micromagnetics and presented hysteresis models in electromagnetic computation. And also, we studied on spin - polarized STM and exchange force microscopy, and analyzed 3 - D magnetic shield problems by using new BEM method. (3) Phenomena exhibited by ballistic 2 - D electron gas in magnetic fields were simulated as motion of electron waves in quantum wires. Concept of quantum - mechanical computers was discussed from view point of quantum information, computation, and multiparticle states. (4) Mesoscopic constitutive modes in type - II superconductors were developed and studies numerically, so that they were used in design and analysis of space equipments and electro - magneto devices. (5) Propose of finite element beam propagation method for nonlinear optical waveguides, development of optical memories system, application of acoustic - optic interaction systems, and experiments on a change in optical spectrum by spatial coherence have been done.
• Equilibrium analysis of free boundary MHD plasma with bootstrap current

  Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research

  Date (from‐to) : 1993 -1994 

  Author : IGARASHI Hajime, KAWAGUCHI Hideki, TSUCHIMOTO Masanori, HONMA Toshihisa

   

  In order to realize steady-state operations in tokamak-type nuclear fusion reactors, there is the method to use bootstrap currents form neoclassical transport theory, which are driven by the thermodynamic force of plasma. This means that plasma itself can sustain the toroidal current for long time. Development of the numerical MHD equilibrium code for free boundary plasma was carried out in 1993. We have compared several viscosity models and applied the Hirshman's rational approximations to the present analysis. In 1994, following analyzes were carried out by using the the numerical code. The bootstrap currents were compared with Ohmic and diamagnetic currents using iterative calculation with Hirshman's viscosity model. The bootstrap currents flow near the plasma surface more than at the center of plasma. That is why the plasma pressure gradient becomes low and no momentum exchange among trapped particles happen near the center of plasma. In comparison of the case with toroidal current Ip=22 (MA) and 15 (MA), ratio of the bootstrap currents of 15 (MA) is larger than that of 22 (MA) because of the poloidal magnetic field. Study for relation between plasma density and temperature was also carried out. Further analysis under consideration of the effects of impurity will be carried out by using the friction and viscosity matrix in the near future.
• Computational Electromagnetism, Soft Computing, System Simulation

  Date (from‐to) : 1989

Industrial Property Rights

• 特願2017-223831:形状最適化結果表示方法及びその装置  2017年/11/21

  五十嵐 一
• 特願2017-223830:形状最適化結果表示方法及びその装置  2017年/11/21

  五十嵐 一
• 特許5697233:環境情報計測装置，環境情報計測システム，及び環境情報計測方法    2015/02/20

  五十嵐 一
• 特願2014-144653:埋め込み型永久磁石回転機  2014年/07/15

  五十嵐 一
• インダクタの設計方法

  特開２０１０－６２２００

Others

• 2015/09 -2015/09 ISEM2015 OS organizer

  Organizer of Organized Session
• 2014/12 -2014/12 MAGDAシンポジウム OS オーガナイザ

  オーガナイズドセッション オーガナイザ
• 2014/11 -2014/11 JSST2015 OS organizer

  Organizer of Organized Session