1. Prof. Dr. W. Liu, D. Li, Prof. Dr. N. Li, Dr. J. Yan; School of Manufacturing Science and Engineering, Sichuan University; Chengdu, 610065 P. R. China
2. D. Li; Department of Mechanical and Electrical Engineering, Chengdu Aeronautic Polytechnic; Chengdu China
3. Prof. Dr. W. Liu, Prof. Dr. S. Shi; Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom; Kowloon Hong Kong