1. College of Computer Science and Electronic Engineering, Hunan University, Changsha, Hunan Province, P.R. China
2. Department of Computer and Information Sciences, Temple University, Philadelphia, PA, USA
3. Institute of Artificial Intelligence and Future Networks, Beijing Normal University & UIC, Zhuhai, Guangdong Province, P. R. China
4. School of Computer Science and Cyber Engineering, Guangzhou University, Guangzhou, Guangdong Province, P.R. China