雾是指大量水滴及冰晶微粒悬浮在贴地层空气中,使水平能见度小于1 km 的一种天气现象。雾形成前期低空出现的逆温会使得城市及周边大气中烟尘污染物SO2及NO2在低空积聚,起雾前,随着SO2及NO2浓度的增加,凝结度迅速增长;雾期间,随着凝结...雾是指大量水滴及冰晶微粒悬浮在贴地层空气中,使水平能见度小于1 km 的一种天气现象。雾形成前期低空出现的逆温会使得城市及周边大气中烟尘污染物SO2及NO2在低空积聚,起雾前,随着SO2及NO2浓度的增加,凝结度迅速增长;雾期间,随着凝结度增长,SO2及NO2浓度反而下降。这表明城市大气污染物作为凝结核在低空堆积对触发雾的形成起重要作用。污染气体SO2、NOx、NH3 的排放产生的二次气溶胶对雾的形成具有重要影响。不考虑这些污染气体排放时,PM2.5 的总质量浓度均有约30%~60%的减少,平均雾水含量值可降低32.2%。展开更多
Copper alloys with high strength and high conductivity are an important functional material with full of potential applications.In the present investigation,a bronze with higher tin content(Cu-13.5 wt pct Sn) was prep...Copper alloys with high strength and high conductivity are an important functional material with full of potential applications.In the present investigation,a bronze with higher tin content(Cu-13.5 wt pct Sn) was prepared successfully by spray forming,the feasibility of cold rolling this alloy was investigated,and the cold rolling characteristics of this alloy have also been discussed.The results indicate that the spray-formed Cu-13.5 wt pct Sn alloy,compared with the as-cast ingot,shows a quite fine and homogeneous single-phase structure,and,therefore shows an excellent workability.It can be cold-rolled with nearly 15% reduction in the thickness per pass and the total reduction can reach 80%.The classical border between the wrought and cast alloys is shifted to considerably higher tin contents by spray forming.After proper thermo-mechanical treatment,spray-formed Cu-13.5 wt pct Sn alloy exhibits excellent comprehensive mechanical properties. Particularly,it shows a low elastic modulus(～88 GPa)and a high flow stress(over 800 MPa)after cold forming.This combination of properties is unique in the domain of metallic materials and could open new possibilities in spring technology field.展开更多
文摘雾是指大量水滴及冰晶微粒悬浮在贴地层空气中,使水平能见度小于1 km 的一种天气现象。雾形成前期低空出现的逆温会使得城市及周边大气中烟尘污染物SO2及NO2在低空积聚,起雾前,随着SO2及NO2浓度的增加,凝结度迅速增长;雾期间,随着凝结度增长,SO2及NO2浓度反而下降。这表明城市大气污染物作为凝结核在低空堆积对触发雾的形成起重要作用。污染气体SO2、NOx、NH3 的排放产生的二次气溶胶对雾的形成具有重要影响。不考虑这些污染气体排放时,PM2.5 的总质量浓度均有约30%~60%的减少,平均雾水含量值可降低32.2%。
基金the Hundred-Talent-Person Project of Chinese Academy of Sciences.
文摘Copper alloys with high strength and high conductivity are an important functional material with full of potential applications.In the present investigation,a bronze with higher tin content(Cu-13.5 wt pct Sn) was prepared successfully by spray forming,the feasibility of cold rolling this alloy was investigated,and the cold rolling characteristics of this alloy have also been discussed.The results indicate that the spray-formed Cu-13.5 wt pct Sn alloy,compared with the as-cast ingot,shows a quite fine and homogeneous single-phase structure,and,therefore shows an excellent workability.It can be cold-rolled with nearly 15% reduction in the thickness per pass and the total reduction can reach 80%.The classical border between the wrought and cast alloys is shifted to considerably higher tin contents by spray forming.After proper thermo-mechanical treatment,spray-formed Cu-13.5 wt pct Sn alloy exhibits excellent comprehensive mechanical properties. Particularly,it shows a low elastic modulus(～88 GPa)and a high flow stress(over 800 MPa)after cold forming.This combination of properties is unique in the domain of metallic materials and could open new possibilities in spring technology field.
