1. Advanced Institute for Computational Science (AICS), RIKEN, 7-1-26, Minatojima-minami-machi, Chuo-Ku, Kobe, Hyogo 650-0047, Japan
2. Department of Mechanical Engineering and Intelligent Systems, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585, Japan