jgg     2010 30 (6):  31-36    ISSN: 0412-1961  CN: 21-1139/TG IMPROVED PARTICLE SWARM OPTIMIZATION ALGORITHM AND ITSAPPLICATION IN INVERSION OF SLIP VELOCITY OF FAULT Duan Hurong 1,2) ;Zhang Yongzhi 1) ; and Xu Haijun 1) 1)School of Geological Engineering and Surveying, Chang’an University, Xi’an 7100542)Shanxi Railway Institute, Weinan 714000 Received: 1900-01-01  Revised: 1900-01-01  Online: null Supporting info null