1. College of Computer Science and Electronic Engineering, Hunan University, Changsha, Hunan, China
2. Chow Yei Ching School of Graduate Studies, City University of Hong Kong, Kowloon Tong, Hong Kong
3. Computer Science and Engineering Department, The Chinese University of Hong Kong, Shatin, Hong Kong
4. School of Computing Science, Simon Fraser University, Burnaby, BC, Canada
5. Department of Computer Science, TU Wien, Vienna, Austria
6. School of Computer Engineering, Nanyang Technological University, Jurong West, Singapore