1. Department of Computer Science and Engineering, Zhuzhou Institute of Technology, Hunan, 412000, P. R. China
2. Department of Scientific Computing and Computer Application, Zhongshan University, P. R. China
3. Department of Computer Science, Hong Kong Baptist University, Kowloon Tong, Hong Kong, P. R. China
4. Department of Computer Science and Technology, Changsha Institute of Technology, P. R. China