1. School of Mathematics and Statistics, Nanjing University of Science and Technology, Nanjing, P. R. China
2. Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques, Gannan Normal University, Ganzhou, P. R. China
3. Interdisciplinary Center for Fundamental and Frontier Sciences, Nanjing University of Science and Technology, Jiangyin, P. R. China
4. National Navel Orange Engineering Research Center, Gannan Normal University, Ganzhou, P. R. China
5. College of Mathematics, Taiyuan University of Technology, Taiyuan, P. R. China
6. Department of Mathematics, Columbus State University, Columbus, GA, USA