1. School of Mathematics and Statistics, Hainan University, Haikou 570228, China
2. Key Laboratory of Engineering Modeling and Statistical Computation of Hainan Province, Hainan University, Haikou 570228, China
3. The School of Mathematics, Tianjin University, Tianjin 300072, China
4. School of Cyberspace Security, Hainan University, Haikou 570228, China