1. School of Mathematics and Computational Science, Xiangtan University, Xiangtan, China
2. College of Information Science and Technology, Jinan University, Guangzhou, China
3. School of Computer Science, Xiangtan University, Xiangtan, China
4. Department of Software, Ajou University, Suwon, South Korea
5. Graduate School of Advanced Integration Science, Chiba University, Chiba, Japan