中文摘要：

E-mail： Guo_Hang@emc.com Hang Guo received his Ph.D. degree from the Department of Computer Science and Technology, Tsinghua University in 2008. His research interests include text mining, machine learning and information re- trieval. E-mail：dcszlz@tsinghua．edu．cnLi-Zhu Zhou is a professor at the Department of Computer Science and Technology, Tsinghua University. He is a member of ACM. His current research interests include database, digital resource management, and data mining E-mail：fengling@tsinghua．edu．cnLing Feng is a professor at the Department of Computer Science and Technology, Tsinghua University. She is a member of CCF, IEEE and ACM. Her research interests include context-aware data management towards ambient intelligence, knowledge-based information systems, data mining and warehousing, and distributed object-oriented database management systems.