1. School of Computer Science and Information Engineering, Hefei University of Technology, Hefei, China
2. Guangzhou Institute of Technology, Xidian University, Guangzhou, China
3. Faculty of Computer Science and Engineering, Xi’an University of Technology, Xi’an, China
4. Department of Information and Electronic Engineering, Muroran Institute of Technology, Muroran, Japan
5. School of Computer Science, University of Oklahoma, Norman, OK, USA
6. Distributed Systems Group, TU Wien, Vienna, Austria