LIU Bo-Ang Master student in the Department of Mathematical Sciences, Tsinghua University. Her research interest covers statistical analysis and its applications. E-mail: demetria@163.com YE t-Iao Professor in the Department of Automation, Tsinghua University. He received his bachelor and Ph.D. degrees in automation from Tsinghua University, in 1992 and 1996, respectively. His research interest covers fault detection and diagnosis of dynamic systems. Corresponding author of this paper. E-mail: haoye@tsinghua.edu.cn