1. School of Mathemat-ics and Computer Sciences, Nanchang University, Nanchang, China
2. Department of Computer Science, Illinois Institute of Technology, Chicago, IL, USA
3. School of Computer Science, Wuhan University, Wuhan, China
4. Department of Computer Science, Hong Kong Baptist University, Hong Kong, China
5. School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore