Vol.20 No.3 杜翠凤：爆破有毒气体的污染预报 ·223· Pollution Prediction of Poison Blasting Gases Du Cuifeng Yang Guoyun Li Huaiyu Resources Eningeering School,UST Beijig.Beijing 100083,China ABSTRACT The mushroom cloud forming in a very short time after blasting and the overflwing gases from the heap that emited very slowly from the heap made u p the amount of the explosive gases.According to their movement characterstics,the mushroom cloud was taken as the souce of instantaneous volume and the overflowing gases from the heap was taken as the irregular volume,their diffusion pattern is selected as the pattern of smoke volume integral.On the basis of consideration,the pollution evaluation pattern of an open-pit was established by simplifing the pattern and amending the diffu- sion coefficient.A reltively accurate pollution prediction on explosive gases in Dayie Iron Mine was carried out. KEY WORDS pollution prediction;pollution source;overflowing gases from the heap 中中平中中中中中中中中中中中中中中中中中中中中中中中平中中中中中中中中中中平中中平中中中中中中中学中中中中 TEM Study of Microcrack Nucleation and Propagation for 310 Stainless Steel Honggi Li Oizhi Chen Yizhong Huang Yanbin Wang Wuyang Chu Applied Science School,UST Beijing,Beijing 100083,China ABSTRACT TEM in situ tensile tests of 310 stainless steel show that a dislocation free zone (DFZ)forms if the displacement keeps constant after dislocations are emitted from a crack tip.The elastic DFZ is gradually thinned and the stress in the DFZ will reach the cohesive strength,resulting in nucleation of nanocracks in it and their bluntness into voids. If continuously tensioning,the inhomogeneously thinning ahead of the crack tip,initiat- ing and connecting of microcracks or microvoids will be observed rather than a DFZ, nanocracks'initiation and bluntness into voids.The inverse pile-up ahead of a loaded crack tip can move back to the crack tip when unloading. KEY WORDS 310 stainless steel;in situ TEM tension;dislocation free zone:initiation of nanocrack (Form:Journal of University of Science und Technology Beijing (English Edition),1998,4(2).100) 中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中中