1. Guangxi Key Laboratory of Embedded Technology and Intelligent System, Guilin University of Technology, 319 Yanshan Street, Guilin, Guangxi, P. R. China
2. School of Information Science and Engineering, Guilin University of Technology, 319 Yanshan Street, Guilin, Guangxi, P. R. China
3. School of Information Engineering, Nanjing Audit University, 86 Yushan West Road, Nanjing, Jiangsu, P. R. China