The single crystal of nickel-base super alloy is widely used for making turbine blades.The microstructure of the alloy,especially the deviation of preferred orientation of single crystal,possesses the most important e...The single crystal of nickel-base super alloy is widely used for making turbine blades.The microstructure of the alloy,especially the deviation of preferred orientation of single crystal,possesses the most important effects on the mechanical properties of the blades.In this study,the single crystal ingot and blade of DZ417G alloy are prepared by means of the spiral crystal selector as well as the directional solidification method,and the effect of the parameters(i.e.,the shape of samples,the withdrawal rate)and the structure of the spiral crystal selector on the formation of single crystal and the crystal orientation are investigated.This method can prepare not only the single crystal ingot with simple shape but also the single crystal blades with the complex shape,the simple with rod-shape can form the single crystal easily with a relatively fast withdrawal rate,but the blade with complex shape requires much slower withdrawal rate to form single crystal.The length of the crystal selector almost has no effect on the crystal orientation.However,the angle of selector plays an obvious role on the orientation;the selector with a smaller angle can effectively reduce the deviation of preferred orientation;the appropriate angle of selector to obtain optimal orientation is found to be around30°and the deviation of preferred orientation is about30°for this selector.展开更多
Enantioseparation of salbutamol solute was carried out in liquid-supported membrane by using a polyvinylidene fluoride hollow-fiber module. The enantioselective transport of solute was facilitated by combinatorial chi...Enantioseparation of salbutamol solute was carried out in liquid-supported membrane by using a polyvinylidene fluoride hollow-fiber module. The enantioselective transport of solute was facilitated by combinatorial chiral selectors, which were dissolved in toluene organic solvent. The effects of molar concentration ratios of salbutamol to combinatorial chiral selectors, and the pH value of buffer solution on enantioseparation were investigated. The results show that when the molar concentration ratio is 2∶1∶1, the maximum separation factor and enantiomer excess are 1.49 and 19.74%, respectively, and the R-enantiomer flux is more than S-enantiomer; the pH value of buffer solution influences the performances of enantioseparartion obviously, and the appropriate range of pH value is 7.07.2.展开更多
风电系统的故障特征导致了传统选相元件存在适用性问题。在分析相电压暂态特征的基础上,提出一种适用于风电接入系统的时域选相元件。理论分析发现,不同故障类型下的各相电压暂态特征之间的相关性存在差异,据此提出了基于相关性的选相...风电系统的故障特征导致了传统选相元件存在适用性问题。在分析相电压暂态特征的基础上,提出一种适用于风电接入系统的时域选相元件。理论分析发现,不同故障类型下的各相电压暂态特征之间的相关性存在差异,据此提出了基于相关性的选相判据。新选相原理利用电压量,不受风电系统弱馈性的影响;基于时域暂态量,受风电系统背侧阻抗不稳定的影响较小。利用PSCAD(power systems computer aided design)软件的建模仿真结果及现场故障录波数据验证了新选相方法的有效性。展开更多
基金Project(51074105)supported by the National Natural Science Foundation of ChinaProjects(08DZ1130100,10520706400)supported by the Science and Technology Commission of Shanghai Municipality,ChinaProject(2007CB613606)supported by the National Basic Research Program of China
文摘The single crystal of nickel-base super alloy is widely used for making turbine blades.The microstructure of the alloy,especially the deviation of preferred orientation of single crystal,possesses the most important effects on the mechanical properties of the blades.In this study,the single crystal ingot and blade of DZ417G alloy are prepared by means of the spiral crystal selector as well as the directional solidification method,and the effect of the parameters(i.e.,the shape of samples,the withdrawal rate)and the structure of the spiral crystal selector on the formation of single crystal and the crystal orientation are investigated.This method can prepare not only the single crystal ingot with simple shape but also the single crystal blades with the complex shape,the simple with rod-shape can form the single crystal easily with a relatively fast withdrawal rate,but the blade with complex shape requires much slower withdrawal rate to form single crystal.The length of the crystal selector almost has no effect on the crystal orientation.However,the angle of selector plays an obvious role on the orientation;the selector with a smaller angle can effectively reduce the deviation of preferred orientation;the appropriate angle of selector to obtain optimal orientation is found to be around30°and the deviation of preferred orientation is about30°for this selector.
文摘Enantioseparation of salbutamol solute was carried out in liquid-supported membrane by using a polyvinylidene fluoride hollow-fiber module. The enantioselective transport of solute was facilitated by combinatorial chiral selectors, which were dissolved in toluene organic solvent. The effects of molar concentration ratios of salbutamol to combinatorial chiral selectors, and the pH value of buffer solution on enantioseparation were investigated. The results show that when the molar concentration ratio is 2∶1∶1, the maximum separation factor and enantiomer excess are 1.49 and 19.74%, respectively, and the R-enantiomer flux is more than S-enantiomer; the pH value of buffer solution influences the performances of enantioseparartion obviously, and the appropriate range of pH value is 7.07.2.
文摘风电系统的故障特征导致了传统选相元件存在适用性问题。在分析相电压暂态特征的基础上,提出一种适用于风电接入系统的时域选相元件。理论分析发现,不同故障类型下的各相电压暂态特征之间的相关性存在差异,据此提出了基于相关性的选相判据。新选相原理利用电压量,不受风电系统弱馈性的影响;基于时域暂态量,受风电系统背侧阻抗不稳定的影响较小。利用PSCAD(power systems computer aided design)软件的建模仿真结果及现场故障录波数据验证了新选相方法的有效性。
