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Meta 2010 & FEM 2010 – Rome, 13-15 December 2010 Application of ON/OFF Method to New Conceptual Design of Magnetic Devices Norio Takahashi Dept. Electrical and Electronic Eng., Okayama Univ. Tsushima, Okayama 700-8530, Japan E-mail: norio@elec.okayama-u.ac.jp In the development of an electromagnetic device, the design based on the experience of designers is usually performed. Recently, various optimal design methods using electromagnetic field analysis are developed and applied to the design of actual magnetic devices. In those methods, we must imagine the outline of the optimal shape of the magnetic circuit, and the dimensions etc. are determined by the optimization software. Therefore, it may be difficult to get a newly developed magnetic circuit which we could not imagine beforehand. If a topology optimization method which can determine the optimal topology by distributing materials in a design domain is used, there is a possibility that a new magnetic circuit can be discovered, because it is not necessary to set design variables in advance. In this paper, the ON/OFF method which can determine the optimal topology considering 3-D shape and the nonlinearity of magnetic material is examined. The effectiveness of the newly developed ON/OFF method is shown applying it to the design of various magnetic devices, such as magnetic head[1], shield[2], motor[3] etc. Fig.1 shows the obtained shape of high density magnetic head. A reasonable shape is obtained. Fig. 2 shows the optimal shape of IPM motor which produces a higher driving torque. References [1] K.Akiyama, D. Miyagi, N.Takahashi, “Design of CF-SPT Head Having Large Recording Field and Small Stray Field Using 3-D ON/OFF Method”, IEEE Trans. on Magn., Vol. 42, No.10, pp.2431-2433, 2006. [2] N. Takahashi, S. Nakazaki, D. Miyagi: “ Examination of Optimal Design Method of Electromagnetic Shield Using ON/OFF Method”, IEEE Trans. on Magn., Vol. 45, no.3, pp.1546- 1549, 2009. [3] N. Takahashi, T. Yamada, D. Miyagi: “Examination Optimal Design of IPM Motor Using ON/OFF Method ”, IEEE Trans. on Magn., Vol.46, No. 8, pp.3149-3152, 2010. 26
Meta 2010 & FEM 2010 – Rome, 13-15 December 2010 Implementation of a 3D Micromagnetic Code on a Parallel and Distributed Architecture Carlo Ragusa (1) , Bartolomeo Montrucchio (2) , Vittorio Giovara (2) , Fiaz Khan (2) , Omar Khan (2) , Maurizio Repetto (1) (1, 3) , and Baochang Xie (1) Politecnico di Torino, Department of Electrical Engineering Torino, Italy – E-mail: carlo.ragusa@polito.it (2) Politecnico di Torino, Department of Control and Computer Engineering Torino, Italy – E-mail: bartolomeo.montrucchio@polito.it (3) Shanghai Jiaotong University (SJTU), Shanghai 200030,China We present the implementation of a full micromagnetic code developed on a low cost and low latency parallel and distributed architecture based on OpenMP [1] and MPI over Infiniband [2]. Since the most time consuming part of a micromagnetic code is the magnetostatic field computation algorithm, many existing parallel implementations take advantage of Ethernet-based computer clusters [3]. Moreover, in recent years, the availability of low cost multi-core and multi-processor computers have enabled the parallelization of micromagnetic programs on shared memory computer systems [4]. In our approach we use a low latency Infiniband network coupled with a low cost multi processor, multi core cluster. The hardware architecture includes a 16 cores cluster composed by two double processor computers. The two computers are connected by means of Infiniband network cards that are directly connected together, without using a switch. The general implementation scheme is summed up in the following. As first, any standard sequential loop is parallelized to fully exploit all the eight cores each single machine can offer. By setting up proper shared/private variables lists, the loop is divided among a given number of OpenMP threads and each carries out a portion of that iteration. Afterwards, the loop is split in two (n in the general case of a n nodes cluster) data sets, before executing OpenMP. Each part of the loop is submitted to a node of the cluster and separately executed. Eventually, at the end of the loop, data is exchanged back with MPI and merged so that the two (n) machines can continue working on complete arrays. References [1] R. Chandra, L. Dagum, D. Kohr, D. Maydan, J. McDonald, R. Menon, Parallel programming in OpenMP, Morgan Kaufmann Publishers, 2001 [2] W. Gropp, E. Lusk, A. Skjellum, Using MPI - Portable parallel programming with the Message- Passing Interface, Scientific and Engineering computation series, The MIT Press, 1999 [3] Y. Kanai, M. Saiki, K. Hirasawa, T. Tsukamomo, and K. Yoshida, IEEE Trans. on Magnetics, 44, 1602, 2008 [4] M.J. Donahue, “Parallelizing a micromagnetic program for use on multiprocessor shared memory computers” IEEE Trans. on Magnetics, 45, 3923-3925, 2009 27
Page 1 and 2: Meta 2010 & FEM 2010 - Rome, 13-15
Page 3 and 4: Meta 2010 - Committees Chairmen Met
Page 7 and 8: Meta 2010 Foreword Ladies and Gentl
Page 9 and 10: FEM 2010 Foreword Ladies and Gentle
Page 25: Session FEM-1 Magnetic device model
Page 43 and 44: Session FEM-3 Methods and solvers M
Page 47 and 48: Session FEM-4 Design and applicatio
Page 67 and 68: Author Index Meta 2010 & FEM 2010 -

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