1. Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and Engineering, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031, PR China
2. The Graduate School of Information, Production and Systems, Waseda University, 2-7 Hibikino, Wakamatsu-ku, Kitakyushu, Fukuoka 808-0135, Japan