1. School of Science, Harbin University of Science and Technology, Harbin, P. R. China
2. School of Information Engineering, Suihua University, Suihua, P. R. China
3. School of Mathematical Sciences, Heilongjiang University and Heilongjiang Provincial Key Laboratory of the Theory and Computation of Complex Systems, Harbin, P. R. China
4. Dalian University of Science and Technology, Dalian, P. R. China