1. College of Information Science and Engineering, Ocean University of China, Qingdao 266100, China.
2. Department of Electrical and Computer Engineering, University of Windsor, Ontario, Canada.
3. College of Engineering, Ocean University of China, Qingdao 266100, China. (e-mail: likunqian@ouc.edu.cn)
4. College of Engineering, Ocean University of China, Qingdao 266100, China.