1. School of Materials Science and Engineering Zhejiang University Hangzhou 310027 China
2. College of Engineering Zhejiang Normal University Jinhua 321004 China
3. College of Electrical Engineering Zhejiang University Hangzhou 310027 China
4. Key Laboratory of Urban Rail Transit Intelligent Operation and Maintenance Technology & Equipment of Zhejiang Province Zhejiang Normal University Jinhua 321004 China