Guizhou Key Laboratory of Economic Systems Simulation, School of Mathematics and Statistics, Guizhou College of Finance and Economics, Guiyang, Guizhou 550004, PR China
Lihui Yang
Department of Mathematics, Hunan City University, Yiyang, Hunan 413000, PR China
Daixi Liao
Basic Science Department, Hunan Institute of Technology, Hengyang, Hunan 421002, PR China