作者机构:[1]Department of Mathematics and Statistics, Shanghai Lixin University of Commerce, Shanghai 201620, P. R. China, [2]College of Sciences, Shanghai University, Shanghai 200444, P. R. China, [3]Hunan Mass Media Technology College, Changsha 410100, P. R. China, [4]Department of Computer Engineering and Information Technology, City University of Hong Kong, Kowloon, Hong Kong, P. R. China
相关基金:Project supported by the National Natural Science Foundation of China (Nos. 10471088 and 60572126) and the Science Foundation of Shanghai Municipal Commission of Education (No.06ZZ84)