To whom correspondence should be addressed. E-mail: guoxd@usst.edu.cn Guo Xudong, born in 1980. She received her Ph. D degrees from Shanghai Jiaotong University in 2008. She also received her B.S. and M.S. degrees from Nan- jing University of Science and Technology in 2002 and 2004, respectively. Her main research interests include precision engineering and intelligent micro-system.