1. School of Mathematics and Statistics Changshu Institute of Technology Changshu 215500 People's Republic of China
2. School of Mathematics China University of Mining and Technology Xuzhou 221116 People's Republic of China
3. State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and Technology Xuzhou 221116 People's Republic of China
4. Department of Mathematics, Faculty of Science King Abdulaziz University Jeddah 21589 Saudi Arabia
5. School of Mechanics and Civil Engineering China University of Mining and Technology Xuzhou 221116 People's Republic of China