作者机构:[1]School of Mathematical Sciences, Qufu Normal University, Qufu 273165, China, [2]Department of Statistics and Actuarial Science, The University of Hong Kong, Hong Kong,China
相关基金:Acknowledgements The authors thank two anonymous referees for their constructive suggestions which have led to much improvement on the paper. The first author is grateful to Professor Xiaowen Zhou for useful discussion. The research of Yuen was supported by a university research grant of the University of Hong Kong. The research of Yin was supported by the National Natural Science Foundation of China (No. 11171179), the Research Fund for the Doctoral Program of Higher Education of China (No. 20133705110002), and the Program for Scientific Research Innovation Team in Colleges and Universities of Shandong Province.