1. School of Software, and the Key Laboratory for Ubiquitous Network and Service Software of Liaoning Province, Dalian University of Technology, Dalian, China
2. International School of Information Science and Engineering, and the Key Laboratory for Ubiquitous Network and Service Software of Liaoning Province, Dalian University of Technology, Dalian, China
3. Research School of Computer Science, Australian National University, Canberra, ACT, Australia
4. Cardiff University, Cardiff, United Kingdom