Corresponding author.Bu Zeng was born in 1975. He received his M.S. degree from Chongqing Normal University of China in 2006. Now he is a Ph.D. candidate in College of Economics and Management, Nanjing University of Aeronautics and Astronautics. His research interests are grey system theory and software design on complicated mathematical models. E-mail: zbljh2@ 163.com Sifeng Liu was born in 1955. He is a professor in the College of Economics and Management, Nanjing University of Aeronautics and Astronau- tics (NUAA). He received his Ph.D. degree in grey theory of Huazhong University of Science and Technology. He is the dean of College of Economics and Management of NUAA. He is the chairman of IEEE Grey System Society and vice chairman of IEEE SMC China (Beiiing) Branch.His research interests include grey systems theory, management science and project management. E-mail: sfliu@ nuaa.edu.cn Naiming Xie was born in 1981. He is a lecturer in the College of Economics and Management of Nanjing University of Aeronautics and Astro- nautics (NUAA). He received his B.S., M.S. and Ph.D. degrees in grey systems theory of NUAA. His research interests include grey systems theory, management science and project management. E-mail: xienaiming @ y ahoo.com.cn