中文摘要：

俞嘉地：To whom correspondence should be addressed. E-mail：{jdyu,li-ml}@ cs.sjtu, edu. cn； Jiadi Yu, born in 1975. He is a postdoc in the Ad Hoc Network and Network Computing Center and the De- partment of Computer Science and Engineering of Shang-hai Jiaotong University. He received his Ph. D degree in Computer Science Department of Shanghai Jiaotong University in 2007. He also received his B.S. and M.S. degrees from Xi＇an Technological University in 1997 and 2002 respectively. His research interests include P2P computing, grid computing, and Ad Hoc network.