Global Geology     2016 19 (1):  33-40    ISSN: 1673-9736:  CN: 22-1371/P Inversion of 3D density interface with PSO- BP method ZHANG Dailei and ZHANG Chong College of Geo- Exploration Science and Technology，Jilin University，Changchun 130026，China Received null  Revised null  Online 2016-03-25 Reference   Corresponding author: