1. Department of Mathematics, School of Mathematics and Information Science, Henan Normal University, Xinxiang 453007, P. R. China
2. Henan Engineering Laboratory for Big Data Statistical Analysis and Optimal Control, School of Mathematics and Information Science, Henan Normal University, Xinxiang 453007, P. R. China
3. School of Mathematics and Statistics, Nanyang Normal University, Nanyang 473061, P. R. China