1. College of Economics and Management, Shandong University of Science and Technology, Qingdao, China and School of Computer Science, Qufu Normal University, Rizhao, China
2. College of Engineering, Qufu Normal University, Rizhao, China
3. School of Computer Science, Qufu Normal University, Rizhao, China
4. Faculty of Information Technology and Electrical Engineering, University of Oulu, Oulu, Finland
5. Department of Computer Science and Technology, Tsinghua University, Beijing, China
6. College of Intelligence and Computing, Tianjin University, Tianjin, China
7. College of Economics and Management, Shandong University of Science and Technology, Qingdao, China