作者机构:[1]Department of Mathematics, Shanghai Normal University, Shanghai 200234, China, [2]Business Information Management School, Shanghai Institute of Foreign Trade, Shanghai 201620 China.
相关基金:Supported by NSFC grant (10671129), the Special istry(20060270002), E-Institutes of Shanghai Municipal Academic Discipline Project (S30405). Funds for Doctoral Authorities of Education Min- Education Commission(E03004), Shanghai Leading