[1] Beijing Univ Aeronaut & Astronaut, Sch Instrumentat Sci & Optoelect Engn, Beijing 100191, Peoples R China
[2] Beijing Univ Aeronaut & Astronaut, Beijing Engn Res Ctr High Speed Magnet Suspended, Beijing 100191, Peoples R China
[3] Hong Kong Univ Sci & Technol, Fok Ying Tung Grad Sch, Kowloon, Hong Kong, Peoples R China