1. School of Mathematics and Statistics, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, P. R. China
2. Key Laboratory of Jiangxi Province, for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou, Jiangxi 341000, P. R. China
3. Interdisciplinary Center for Fundamental and Frontier Sciences, Nanjing University of Science and Technology, Jiangyin, Jiangsu 214443, P. R. China
4. School of Mathematical Science, Yangzhou University, Yangzhou, Jiangsu 225009, P. R. China
5. College of Mathematics and Computer Science, Zhejiang Normal University, Jinhua, Zhejiang 321004, P. R. China
6. Department of Mathematics, Columbus State University, Columbus, GA 31907, USA