1. Three Gorges Mathematical Research Center, China Three Gorges University, Yichang 443002, P. R. China
2. School of Mathematics and Computer Science, Yunnan Minzu University, Kunming 650500, P. R. China
3. Engineering Research Center of Eco-Environment, in Three Gorges Reservoir Region, Ministry of Education, China Three Gorges University, Yichang 443002, P. R. China
4. Key Laboratory of IOT Application Technology of Universities in Yunnan Province, Yunnan Minzu University, Kunming 650500, P. R. China
5. Department of Applied Mathematics, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada