1. College of Mathematics and Informatics, Fujian Normal University, Fuzhou, P.R. China
2. College of Mathematics and Informatics, Fujian Normal University, Fuzhou, 350007, China
3. Laboratory of Mathematics and Complex Systems (MOE), School of Mathematical Sciences, Beijing Normal University, Beijing, China
4. Laboratory of Mathematics and Complex Systems (MOE), School of Mathematical Sciences, Beijing Normal University, Beijing, 100875, China