1. Key Laboratory of Urban Rail Transit Intelligent Operation and Maintenance Technology & Equipment of Zhejiang Province College of Engineering Zhejiang Normal University Jinhua 321004 P. R. China
2. Jinhua Intelligent Manufacturing Research Institute Jinhua 321004 P. R. China
3. Beijing Institute of Nanoenergy and Nanosystems Chinese Academy of Sciences Beijing 100083 P. R. China
4. MOE Key Laboratory of Hydraulic Machinery Transients School of Power and Mechanical Engineering Wuhan University Wuhan 430072 P. R. China
5. College of Nanoscience and Technology University of Chinese Academy of Sciences Beijing 100049 P. R. China
6. School of Materials Science and Engineering Georgia Institute of Technology Atlanta GA 30332 USA