1. State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240, China e-mail:
2. State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240, China
3. Naval Research Center, Box 1303-14, Beijing 100073, China