Corrosion leakages often occur in the air cooler of a hydrocracking unit,with the failure sites mainly located in the entrance area of the tubes.An analysis of the macroscopic morphology and corrosion products confirm...Corrosion leakages often occur in the air cooler of a hydrocracking unit,with the failure sites mainly located in the entrance area of the tubes.An analysis of the macroscopic morphology and corrosion products confirmed that the damage was caused by erosion-corrosion(E-C).Numerical and experimental methods were applied to investigate the E-C mechanism in the air cooler.Computational fluid dynamics(CFD)was used to calculate the hydrodynamic parameters of the air cooler.The results showed that there was a biased flow in the air cooler,which led to a significant increase in velocity,turbulent kinetic energy and wall shear within 0.2 m of the tube entrance.A visualization experiment was then performed to determine the principles of migration and transformation of multiphase flow in the air cooler tubes.Various flow patterns(pure droplet flow,mist flow,and annular flow)and their evolutionary processes were clearly depicted experimentally.The initiation mechanism and processes leading to the development of E-C in the air cooler were also determined.This study provided a comprehensive explanation for the E-C failures that occur in air coolers during operation.展开更多
目的探讨瑞芬太尼全身麻醉对剖宫产产妇血流动力学及新生儿结局的影响。方法纳入我院2019年7月至2020年7月收治的100例剖宫产产妇,根据麻醉方案不同将其分为对照组(n=50,常规麻醉)和试验组(n=50,瑞芬太尼全身麻醉)。比较两组的麻醉效果...目的探讨瑞芬太尼全身麻醉对剖宫产产妇血流动力学及新生儿结局的影响。方法纳入我院2019年7月至2020年7月收治的100例剖宫产产妇,根据麻醉方案不同将其分为对照组(n=50,常规麻醉)和试验组(n=50,瑞芬太尼全身麻醉)。比较两组的麻醉效果。结果拔管时、术后24 h,两组的皮质醇(Cor)、心房利钠肽(ANP)及C反应蛋白(CRP)水平均高于麻醉前,但试验组低于对照组(P<0.05)。插管后至手术结束时(T_(1)~T_(3))时,两组的平均动脉压(MAP)、心率(HR)均低于麻醉前(T_(0))时,但试验组高于对照组(P<0.05);T_(1)、T_(3)时,试验组的中心静脉压(CVP)、心排血量(CO)与T0时无显著差异(P>0.05)。两组的出生1 min Apgar评分及脐动脉血气指标无显著差异(P>0.05)。术后,试验组的白细胞分化抗原3阳性(CD3_(+))、白细胞分化抗原4阳性(CD4^(+))、白细胞分化抗原8阳性(CD8_(+))及CD4^(+)/CD8^(+)与术前无显著差异(P>0.05)。结论瑞芬太尼全身麻醉有助于减轻产妇的应激反应,维持产妇血流动力学稳定,且对新生儿影响较小,麻醉镇痛效果显著。展开更多
基金supported by the National Key R&D Program of China(2021YFB3301100)Beijing University of Chemical Technology Interdisciplinary Program(XK2023-07).
文摘Corrosion leakages often occur in the air cooler of a hydrocracking unit,with the failure sites mainly located in the entrance area of the tubes.An analysis of the macroscopic morphology and corrosion products confirmed that the damage was caused by erosion-corrosion(E-C).Numerical and experimental methods were applied to investigate the E-C mechanism in the air cooler.Computational fluid dynamics(CFD)was used to calculate the hydrodynamic parameters of the air cooler.The results showed that there was a biased flow in the air cooler,which led to a significant increase in velocity,turbulent kinetic energy and wall shear within 0.2 m of the tube entrance.A visualization experiment was then performed to determine the principles of migration and transformation of multiphase flow in the air cooler tubes.Various flow patterns(pure droplet flow,mist flow,and annular flow)and their evolutionary processes were clearly depicted experimentally.The initiation mechanism and processes leading to the development of E-C in the air cooler were also determined.This study provided a comprehensive explanation for the E-C failures that occur in air coolers during operation.
文摘目的探讨瑞芬太尼全身麻醉对剖宫产产妇血流动力学及新生儿结局的影响。方法纳入我院2019年7月至2020年7月收治的100例剖宫产产妇,根据麻醉方案不同将其分为对照组(n=50,常规麻醉)和试验组(n=50,瑞芬太尼全身麻醉)。比较两组的麻醉效果。结果拔管时、术后24 h,两组的皮质醇(Cor)、心房利钠肽(ANP)及C反应蛋白(CRP)水平均高于麻醉前,但试验组低于对照组(P<0.05)。插管后至手术结束时(T_(1)~T_(3))时,两组的平均动脉压(MAP)、心率(HR)均低于麻醉前(T_(0))时,但试验组高于对照组(P<0.05);T_(1)、T_(3)时,试验组的中心静脉压(CVP)、心排血量(CO)与T0时无显著差异(P>0.05)。两组的出生1 min Apgar评分及脐动脉血气指标无显著差异(P>0.05)。术后,试验组的白细胞分化抗原3阳性(CD3_(+))、白细胞分化抗原4阳性(CD4^(+))、白细胞分化抗原8阳性(CD8_(+))及CD4^(+)/CD8^(+)与术前无显著差异(P>0.05)。结论瑞芬太尼全身麻醉有助于减轻产妇的应激反应,维持产妇血流动力学稳定,且对新生儿影响较小,麻醉镇痛效果显著。
