1. School of Computer and Software Engineering, Xihua University, Chengdu, People's Republic of China
2. Xihua Honor College, Xihua University, Chengdu, People's Republic of China
3. School of Computer Science and Engineering, Hunan University of Science and Technology, Xiangtan, People's Republic of China
4. Department of Computer Science and Mathematics, Sul Ross State University, Alpine, TX, USA
5. Zhejiang Informatization Development Institute, Hangzhou Dianzi University, Hangzhou, People's Republic of China