1. School of Computer Science and Engineering, South China University of Technology, Guangzhou, China
2. School of Medical Information Engineering, Guangdong Pharmaceutical University, Guangzhou, China
3. Engineering and Technology Institute, Dongguan University of Technology, Dongguan, China. E-mails: rywang@scut.edu.cn, liu.zhen@mail.scut.edu.cn, ming.tao@mail.scut.edu.cn, ling@scut.edu.cn