1. School of Computer and Electronic Information, Nanjing Normal University, Nanjing 210023, China
2. School of Electrical and Automation Engineering, Nanjing Normal University, Nanjing 210023, China
3. College of Electronic Engineering, Nanjing Xiaozhuang University, Nanjing 211171, China
4. Faculty of Engineering, Shizuoka University, Naka-Ku, Johoku, Hamamatsu 432-8561, Japan