It was found that copper powder after 20h of milling shows the formation of a number of mechanical twins. The observed twins belong to two types: multiple twins and high-order ones.It is suggested that Venables model ...It was found that copper powder after 20h of milling shows the formation of a number of mechanical twins. The observed twins belong to two types: multiple twins and high-order ones.It is suggested that Venables model on mechanical twins in face-center-cubic metals is reasonable in this case. The generation of mechanical twins could be explained as follows:the shear stress (P_(max)) induced by ball milling exceeds the critical shear stress for twinning(τ):the grain size decreases to a critical value below which twinning rather than slip is the preferred mode of deformation as well as the strain rate induced by ball milling is high.展开更多
A kind of new catalyst-carbonaceous catalyst-for CH_(4)-CO_(2) reformation has been developed in our laboratory.The effect of both oxygen-bearing functional group such as phenolic hydroxyl,carbonyl,carboxyl,and lacton...A kind of new catalyst-carbonaceous catalyst-for CH_(4)-CO_(2) reformation has been developed in our laboratory.The effect of both oxygen-bearing functional group such as phenolic hydroxyl,carbonyl,carboxyl,and lactonic,and ash such as Fe_(2)O_(3),Na_(2)CO_(3),and K_(2)CO_(3) in the carbonaceous catalyst on the CH_(4)-CO_(2) reforming has been investigated with a fixed-bed reactor.It has been found that the carbonaceous catalyst is an efficient catalyst on CO_(2)-CH_(4) reforming.With the decrease of oxygen-bearing functional group,the catalytic activity of carbonaceous catalyst decreases quickly.The oxygen-bearing functional groups play a significant role in the carbonaceous-catalyzed CO_(2)-CH_(4) reforming;the ash components in carbonaceous catalyst also have an important influence on the CO_(2)-CH_(4) reforming.Fe_(2)O_(3),Na_(2)CO_(3),and K_(2)CO_(3) in the ash can catalyze the CO_(2)-CH_(4) reforming reaction;CaO has little effect on CO_(2)-CH_(4) reforming reaction.CaO can catalyze the gasification between carbonaceous catalyst and CO_(2);Al_(2)O_(3) and MgO inhibit the CO_(2)-CH_(4) reforming.展开更多
基于BS EN 15227:2020标准对一列10辆编组市域地铁列车撞击15 t可变形障碍物耐撞性能进行研究。首先,根据标准要求,对15 t可变形障碍物进行有限元模拟,得到障碍物等效模型;其次,建立列车碰撞模型,进行车辆与障碍物三维碰撞分析;最后,对...基于BS EN 15227:2020标准对一列10辆编组市域地铁列车撞击15 t可变形障碍物耐撞性能进行研究。首先,根据标准要求,对15 t可变形障碍物进行有限元模拟,得到障碍物等效模型;其次,建立列车碰撞模型,进行车辆与障碍物三维碰撞分析;最后,对车辆司机室骨架进行结构优化,并进行最终仿真验证。验证结果表明,优化设计后的列车在与障碍物发生碰撞工况时,可满足列车司机室逃生空间、防爬、加速度等标准要求。展开更多
文摘It was found that copper powder after 20h of milling shows the formation of a number of mechanical twins. The observed twins belong to two types: multiple twins and high-order ones.It is suggested that Venables model on mechanical twins in face-center-cubic metals is reasonable in this case. The generation of mechanical twins could be explained as follows:the shear stress (P_(max)) induced by ball milling exceeds the critical shear stress for twinning(τ):the grain size decreases to a critical value below which twinning rather than slip is the preferred mode of deformation as well as the strain rate induced by ball milling is high.
基金the National Basic Research Program of China(2005CB221202)Shanxi Provincial Natural Science Foundation(20051020)for financial support of the present study。
文摘A kind of new catalyst-carbonaceous catalyst-for CH_(4)-CO_(2) reformation has been developed in our laboratory.The effect of both oxygen-bearing functional group such as phenolic hydroxyl,carbonyl,carboxyl,and lactonic,and ash such as Fe_(2)O_(3),Na_(2)CO_(3),and K_(2)CO_(3) in the carbonaceous catalyst on the CH_(4)-CO_(2) reforming has been investigated with a fixed-bed reactor.It has been found that the carbonaceous catalyst is an efficient catalyst on CO_(2)-CH_(4) reforming.With the decrease of oxygen-bearing functional group,the catalytic activity of carbonaceous catalyst decreases quickly.The oxygen-bearing functional groups play a significant role in the carbonaceous-catalyzed CO_(2)-CH_(4) reforming;the ash components in carbonaceous catalyst also have an important influence on the CO_(2)-CH_(4) reforming.Fe_(2)O_(3),Na_(2)CO_(3),and K_(2)CO_(3) in the ash can catalyze the CO_(2)-CH_(4) reforming reaction;CaO has little effect on CO_(2)-CH_(4) reforming reaction.CaO can catalyze the gasification between carbonaceous catalyst and CO_(2);Al_(2)O_(3) and MgO inhibit the CO_(2)-CH_(4) reforming.
文摘基于BS EN 15227:2020标准对一列10辆编组市域地铁列车撞击15 t可变形障碍物耐撞性能进行研究。首先,根据标准要求,对15 t可变形障碍物进行有限元模拟,得到障碍物等效模型;其次,建立列车碰撞模型,进行车辆与障碍物三维碰撞分析;最后,对车辆司机室骨架进行结构优化,并进行最终仿真验证。验证结果表明,优化设计后的列车在与障碍物发生碰撞工况时,可满足列车司机室逃生空间、防爬、加速度等标准要求。
