1. School of Computer Science and Technology, Hainan University, Haikou, China
2. Department of Computer Science, St. Francis Xavier University, Antigonish, NS, Canada
3. Institute of Information Engineering, Chinese Academy of Sciences, Beijing, China
4. School of Automation Science and Electrical Engineering, Beihang University, Beijing, China
5. Department of Electrical and Computer Engineering, McMaster University, Hamilton, ON, Canada