1. Guizhou Key Laboratory of Economics System Simulation, Guizhou University of Finance and Economics, Guiyang, P.R. China
2. School of Mathematics and Statistics, Guizhou University of Finance and Economics, Guiyang, P.R. China
3. School of Mathematics and Physics, University of South China, Hengyang, P.R. China
4. School of Mathematics and Statistics, Henan University of Science and Technology, Luoyang, P.R. China