1. Faculty of Information Technology, Beijing University of Technology, Beijing 100124, China
2. Department of Computer Science, King Khalid University, Abha 61421, Saudi Arabia
3. School of Computing and Mathematical Science, Faculty of Engineering and Science, University of Greenwich, London SE10 9LS, UK
4. School of Engineering, Edith Cowan University, Perth, WA 6027, Australia
5. School of Computer Science and Engineering, University of Salford, Manchester M5 4BR, UK