The galvanic corrosion of the Q-phase/Al couple in 0.1 M NaCl solutions has been studied using the scanning vibrating electrode technique (SVET)f the scanning ion-selective electrode technique (SIET) and energy disper...The galvanic corrosion of the Q-phase/Al couple in 0.1 M NaCl solutions has been studied using the scanning vibrating electrode technique (SVET)f the scanning ion-selective electrode technique (SIET) and energy dispersive X-ray spectroscopy (EDX). The galvanic corrosion of the Q-phase/Al couple was found to be dependent on pH and immersion time. Current density maps obtained by SVET shows that the anodic oxidation processes emerge from Al in a localized manner in pH 2 and 6 solutions but is initiated in a uniform manner in pH 13 solution, whereas, the cathodic processes are more homogeneously distributed over the Q-phase at pH 2.6 and 13. It is seen that the Q-phase remains cathodic in the Q-phase/Al couple in acidic, neutral and alkaline solutions indicating that the galvanic polarity of the Q-phase is independent of pH. The effect of the galvanic corrosion was largest at pH 2 and 13 compared to pH 6. The pH map obtained by SIET indicates that the galvanic activity of the Q-phase/Al couple proceeds via heavy alkalization of the Q-phase surface with the generation of appreciable amounts of OH~ ions. The enrichment of Cu indicated by EDX is responsible for the observed cathodic activity of the Q-phase in the Q-phase/Al couple.展开更多
A ternary system comprising Ca_(20)Al_(26)Mg_(3)Si_(3)O_(68)(Q-phase),limestone,and metakaolin is proposed,and its hydration behavior,hydration product phases,microstructure,and mechanical properties are investigated ...A ternary system comprising Ca_(20)Al_(26)Mg_(3)Si_(3)O_(68)(Q-phase),limestone,and metakaolin is proposed,and its hydration behavior,hydration product phases,microstructure,and mechanical properties are investigated and compared with pure Q-phase cement.The results indicate that the ternary system exhibits exceptional and sustained compressive strength even under a 40℃environment,significantly outperforming pure Q-phase.The mechanism lies in that metakaolin effectively inhibits the transformation of metastable phase.Meanwhile,the interactions among Q-phase,limestone,and metakaolin further enhance the cementitious performance.The ternary system effectively addresses potential issues of strength loss in Q-phase cement application,and as a low-carbon cementitious material system,it holds promising potential applications.展开更多
地震波在储层岩石中传播会形成流体压力梯度,引起孔隙间流体相对流动,表现为速度频散及衰减现象,进而影响地震波场特征.然而,传统考虑流体赋存影响的衰减岩石物理模型均假设孔隙中流体不相溶,而实际上流体之间必然发生溶解及扩散作用,...地震波在储层岩石中传播会形成流体压力梯度,引起孔隙间流体相对流动,表现为速度频散及衰减现象,进而影响地震波场特征.然而,传统考虑流体赋存影响的衰减岩石物理模型均假设孔隙中流体不相溶,而实际上流体之间必然发生溶解及扩散作用,导致其无法有效刻画孔隙流体赋存影响,影响了地震岩石物理模型精度.波致气体溶解出溶机制(Wave Induced Gas Exsolution and Dissolution,WIGED)能够很好地解释在多相流体相互溶解和扩散导致的衰减作用.目前,尚无针对性的岩石物理实验观测在双相流体中压力梯度引起的溶解-扩散作用,制约了基于该衰减理论的岩石物理模型应用.本文针对双相(气、液)、可相溶流体饱和岩石中的地震波衰减展开测量及衰减特征分析.通过搭建岩石物理衰减测量仪器,观测到了气泡随压力(地震波产生的压力扰动)变化而发生的形变,理论模型数值计算验证了波致气体溶解出溶(WIGED)机制描述地震频带内衰减的有效性.这种地震波衰减特征与地层温度、压力、流体赋存状态、孔隙结构、裂缝发育等因素关系密切,衰减曲线特征可基于标准线性固体模型有效刻画.展开更多
采用磁控管做功率源的低能电子直线加速器在医疗、辐照、X射线检测等领域得到较为广泛的应用。磁控管产生的微波信号输入到加速管,对电子束进行加速,磁控管的工作频率稳定性对加速器电子束能量、能散及发射度产生直接的影响。但磁控管...采用磁控管做功率源的低能电子直线加速器在医疗、辐照、X射线检测等领域得到较为广泛的应用。磁控管产生的微波信号输入到加速管,对电子束进行加速,磁控管的工作频率稳定性对加速器电子束能量、能散及发射度产生直接的影响。但磁控管是一种振荡器,其频率受到温度、振动、负载牵引的影响会产生漂移,所以需要一套自动频率控制系统(Automatic Frequency Control,AFC)机构对磁控管进行频率控制。目前普遍采用的AFC机构主要是行波控相或双腔鉴频,对两路检波信号差分放大进而控制伺服电机进行调谐的方法实现磁控管的频率稳定。随着数字化I/Q和FPGA(Field-Programmable Gate Array)技术的不断发展,运用该技术进行磁控管的频率控制完全具备可行性。本文从理论和工程设计上阐述了数字化I/Q技术在磁控管频率控制上的应用。展开更多
基金financially supported by the National Natural Science Foundation of China (Grant No. 51571201)
文摘The galvanic corrosion of the Q-phase/Al couple in 0.1 M NaCl solutions has been studied using the scanning vibrating electrode technique (SVET)f the scanning ion-selective electrode technique (SIET) and energy dispersive X-ray spectroscopy (EDX). The galvanic corrosion of the Q-phase/Al couple was found to be dependent on pH and immersion time. Current density maps obtained by SVET shows that the anodic oxidation processes emerge from Al in a localized manner in pH 2 and 6 solutions but is initiated in a uniform manner in pH 13 solution, whereas, the cathodic processes are more homogeneously distributed over the Q-phase at pH 2.6 and 13. It is seen that the Q-phase remains cathodic in the Q-phase/Al couple in acidic, neutral and alkaline solutions indicating that the galvanic polarity of the Q-phase is independent of pH. The effect of the galvanic corrosion was largest at pH 2 and 13 compared to pH 6. The pH map obtained by SIET indicates that the galvanic activity of the Q-phase/Al couple proceeds via heavy alkalization of the Q-phase surface with the generation of appreciable amounts of OH~ ions. The enrichment of Cu indicated by EDX is responsible for the observed cathodic activity of the Q-phase in the Q-phase/Al couple.
基金Funded by the National Natural Science Foundation of China(No.52172026)the Science and Technology Development Project of China Railway Design Corporation(Nos.2023A0226407 and 2023B03040003)。
文摘A ternary system comprising Ca_(20)Al_(26)Mg_(3)Si_(3)O_(68)(Q-phase),limestone,and metakaolin is proposed,and its hydration behavior,hydration product phases,microstructure,and mechanical properties are investigated and compared with pure Q-phase cement.The results indicate that the ternary system exhibits exceptional and sustained compressive strength even under a 40℃environment,significantly outperforming pure Q-phase.The mechanism lies in that metakaolin effectively inhibits the transformation of metastable phase.Meanwhile,the interactions among Q-phase,limestone,and metakaolin further enhance the cementitious performance.The ternary system effectively addresses potential issues of strength loss in Q-phase cement application,and as a low-carbon cementitious material system,it holds promising potential applications.
文摘地震波在储层岩石中传播会形成流体压力梯度,引起孔隙间流体相对流动,表现为速度频散及衰减现象,进而影响地震波场特征.然而,传统考虑流体赋存影响的衰减岩石物理模型均假设孔隙中流体不相溶,而实际上流体之间必然发生溶解及扩散作用,导致其无法有效刻画孔隙流体赋存影响,影响了地震岩石物理模型精度.波致气体溶解出溶机制(Wave Induced Gas Exsolution and Dissolution,WIGED)能够很好地解释在多相流体相互溶解和扩散导致的衰减作用.目前,尚无针对性的岩石物理实验观测在双相流体中压力梯度引起的溶解-扩散作用,制约了基于该衰减理论的岩石物理模型应用.本文针对双相(气、液)、可相溶流体饱和岩石中的地震波衰减展开测量及衰减特征分析.通过搭建岩石物理衰减测量仪器,观测到了气泡随压力(地震波产生的压力扰动)变化而发生的形变,理论模型数值计算验证了波致气体溶解出溶(WIGED)机制描述地震频带内衰减的有效性.这种地震波衰减特征与地层温度、压力、流体赋存状态、孔隙结构、裂缝发育等因素关系密切,衰减曲线特征可基于标准线性固体模型有效刻画.
文摘采用磁控管做功率源的低能电子直线加速器在医疗、辐照、X射线检测等领域得到较为广泛的应用。磁控管产生的微波信号输入到加速管,对电子束进行加速,磁控管的工作频率稳定性对加速器电子束能量、能散及发射度产生直接的影响。但磁控管是一种振荡器,其频率受到温度、振动、负载牵引的影响会产生漂移,所以需要一套自动频率控制系统(Automatic Frequency Control,AFC)机构对磁控管进行频率控制。目前普遍采用的AFC机构主要是行波控相或双腔鉴频,对两路检波信号差分放大进而控制伺服电机进行调谐的方法实现磁控管的频率稳定。随着数字化I/Q和FPGA(Field-Programmable Gate Array)技术的不断发展,运用该技术进行磁控管的频率控制完全具备可行性。本文从理论和工程设计上阐述了数字化I/Q技术在磁控管频率控制上的应用。
