1. State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering and School of Mathematics, China University of Mining and Technology, Xuzhou 221116, P. R. China
2. Department of Mathematics, Faculty of Science, King Abdulaziz University P. O. Box 80257, Jeddah 21589, Saudi Arabia
3. Department of Mathematics, College of Science, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 02447, Republic of Korea
4. Qin Institute of Mathematics, Shanghai Hanjing Center of Science and Technology, Yexie Town 201609, Songjiang District, Shanghai, P. R. China