1. School of Electrical and Information Engineering, Tianjin University, Tianjin, China
2. School of Information Technology, Jiangxi University of Finance and Economics, Nanchang, China
3. School of Computer and Software, Nanjing University of Information Science and Technology, Nanjing, China
4. Department of Computer Science and Engineering, Santa Clara University, Santa Clara, CA, USA
5. Department of Computer Science, City University of Hong Kong, Hong Kong, China