1. School of Mathematical Sciences, Zhejiang University of Technology, Hangzhou, 310023, P. R. China
2. School of Statistics and Information, Shanghai University of International Business and Economics, Shanghai, 201620, P. R. China
3. School of Mathematical Science, Shanghai Jiao Tong University, Shanghai, 200240, P. R. China
4. Fuyao University of Science and Technology, Fuzhou, 350300, P. R. China