基金
This research is supported by the Key Project of the National Natural Science Foundation of China under Grant No. 10631070, the National Natural Science Foundation of China under Grant Nos. 10801112, 10971223, 11071252, and the Ph.D Graduate Start Research Foundation of Xinjiang University Funded Project under Grant No. BS080101. Thank Dr. Yong Wang from Institute of Systems Science, Academy of Mathematics and Systems Science for kind discussion and good suggestions.