1. Associate Professor, Shanghai Key Laboratory of Digital Manufacture for Thin-Walled Structures, Shanghai Jiao Tong Univ., Shanghai 200240, P.R. China; State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong Univ., Shanghai 200240, P.R. China; and School of Mechanical Engineering, Shanghai Jiao Tong Univ., No. 800 Dongchuan Rd., Shanghai 200240, China.