1. Research Center of Dynamical Systems and Control, Suzhou University, Suzhou, Anhui 234000, P. R. China
2. School of Earth and Space Sciences, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China
3. Shanghai Hanjing Centre for Science and Technology, Qin Institute of Mathematics, Shanghai 201609, P. R. China
4. School of Resources and Civil Engineering, Suzhou University, Suzhou, Anhui 234000, P. R. China