1. School of Mathematical Science and Fujian Provincial Key Laboratory on Mathematical Modeling and High Performance Scientific Computing, Xiamen University, Xiamen, Fujian, 361005, P. R. China
2. School of Mathematical Sciences, Xiamen University, Xiamen, Fujian, 361005, P. R. China
3. School of Mathematics and Statistics, Minnan Normal University, Zhangzhou, Fujian, 363000, P. R. China