1. College of Computer Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China
2. School of Computer Science and Engineer, Southeast University, Nanjing 210096, China
3. Department of Mathematics and Science Education, Faculty of Education, Harran University, Sanliurfa, Turkey
4. School of Information Science and Technology, Yunnan Normal University, Kunming 650500, China