作者机构:[1]School of Mathematical Sience and Computing Technology, Central South University, Changsha 410083, P. R. China, [2]College of Mathematics and Computer Science, Hunan Normal University, Changsha 410081, P. R. China
相关基金:Project supported by the National Natural Science Foundation of China (No.10671002), the Natural Science Foundation of Hunan Province of China (No.04JJ3072) and the Science Foundation of the Education Department of Hunan Province of China (No.04C383)