1. Shanxi Key Laboratory of Mathematical Techniques and Big Data Analysis on Disease Control and Prevention, Complex Systems Research Center, Shanxi University, Taiyuan 030006, P. R. China
2. Key Laboratory of Complex Systems and Intelligent Optimization of Guizhou Province, School of Mathematics and Statistics, Qiannan Normal University for Nationalities, Duyun 558000, P. R. China
3. School of Mathematics and Statistics, Southwest University, Chongqing 400715, P. R. China