1. School of Science, Beijing University of Technology, Beijing 100124, China
2. School of Mathematics and Statistics, Nanyang Normal University, Nanyang 473061, China
3. School of Mathematical Sciences, Henan Institute of Science and Technology, Xinxiang 453003, China
4. Postdoctoral Research Station of Control Science and Engineering, Henan University of Science and Technology, Luoyang 471023, China