作者机构:[1]School of Mathematical Sciences, Dalian University of Technology, Liaoning 116024, P. R. China, [2]Department of Mathematics, Southeast University, Jiangsu 210096, P. R. China, [3]College of Applied Science, Beijing University of Technology, Beijing 100022, P. R. China
相关基金:Supported by the National Nature Science Foundation of China (Grant No. 10871220) and "Mathematics+X" of DLUT (Grant No. 842328).