1. School of Computer, Electronics and Information, Guangxi Key Laboratory of Multimedia Communications and Network Technology, Guangxi University, Nanning, China
2. School of Computer, Electronics and Information, Guangxi University, Nanning, China
3. Department of Computer Science, Montclair State University, Upper Montclair, NJ, USA
4. College of Information Engineering, Nanning University, Nanning, Guangxi, China