1. School of Science, Xi’an Polytechnic University, Xi’an 710048, China
2. College of Mathematics and Information Science, Shaanxi Normal University, Xi’an 710062, China
3. School of Computer Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China
4. Department of Mathematics, Faculty of Science, Al-Azhar University, Assiut 71524, Egypt