1. Department of Computer Science and Engineering, The University of Aizu, Aizuwakamatsu, Japan
2. School of Intelligent System Engineering, Sun Yat-sen University, Guangzhou, Guangdong Province, China
3. Department of Computer Science, City University of Hong Kong, Hong Kong, Hong Kong
4. School of Electronics and Information Engineering, Nanjing University of Information Science & Technology, Nanjing, China
5. Department of IT, Melbourne Polytechnic, Prahran Campus, Melbourne, VIC, Australia