1. School of Mathematics and Statistics, Chongqing Three Gorges University, Chongqing 404020, China
2. School of Computer Science, Guangdong University of Science & Technology, Dongguan 523083, China
3. State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining 810016, China
4. School of Sciences, Nanchang Institute of Technology, Nanchang 330099, China
5. Department of Computer Technology and Applications, Qinghai University, Xining 810016, China