1. School of Mathematics and Computing Science, Guilin University of Electronic Technology, Guilin 541004, P. R. China
2. School of Information and Software Engineering, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
3. Key Laboratory of Data Analysis and Computing, Guangxi University Laboratory, Guilin 541004, China
4. College of Management Science, Chengdu University of Technology, Chengdu 610059, P. R. China