WEI Xiu-ye is now a PhD candidate and an associate professor in the College of Mechanical Engineering and Automation, North University of China. Her research interests include mechanical design and theory, mechanical fault diagnosis and evolutionary algorithms. PAN Hong-xia is now a professor in the College of Mechanical Engineering and Automation, North University of China. His research interests include mechanical structural dynamics, mechanical fault diagnosis and evolutionary algorithms. I-IUANG Jin-ying is now a professor in the College of Mechanical Engineering and Automation, North University of China. Her research interests include fault diagnosis and dynamic analysis & vibration control. WANG Fu-jie is now an assistant in the College of Mechanical Engineering and Automation, North University of China. His research interests include signal process and computer vision.