Flow in tidal rivers periodically propagates upstream or downstream under tidal influence. Hydrodynamic models based on the Saint-Venant equations （the SVN model） are extensively used to model tidal rivers. A force-...Flow in tidal rivers periodically propagates upstream or downstream under tidal influence. Hydrodynamic models based on the Saint-Venant equations （the SVN model） are extensively used to model tidal rivers. A force-corrected term expressed as the combination of flow velocity and the change rate of the tidal fevel was developed to represent tidal effects in the SVN model. A momentum equation incorporating with the corrected term was derived based on Newton＇s second law. By combing the modified momentum equation with the continuity equation, an improved SVN model for tidal rivers （the ISVN model） was constructed. The simulation of a tidal reach of the Qiantang River shows that the ISVN model performs better than the SVN model. It indicates that the corrected force derived for tidal effects is reasonable; the ISVN model provides an appropriate enhancement of the SVN model for flow simulation of tidal rivers.展开更多
Transverse pressure gradient(TPG)is one of the key factors influencing the boundary layer airflow diversion in a bump inlet.This paper proposes a novel TPG-based hypersonic bump inlet design method.This method consist...Transverse pressure gradient(TPG)is one of the key factors influencing the boundary layer airflow diversion in a bump inlet.This paper proposes a novel TPG-based hypersonic bump inlet design method.This method consists of two steps.First,a parametric optimization approach is employed to design a series of 2D inlets with various compression efficiencies.Then,according to the prescribed TPG,the optimized inlets are placed in different osculating planes to generate a 3D bump inlet.This method provides a means to directly control the aerodynamic parameters of the bump rather than the geometric parameters.By performing this method to a hypersonic chin inlet,a long and wide bump surface is formed in the compression wall,which leads to good integration of the bump/inlet.Results show that a part of the near-wall boundary layer flow is diverted by the bump,resulting in a slight decrease in the mass flow but a significant improvement in the total pressure recovery.In addition,the starting ability is significantly improved by adding the bump surface.Analysis reveals that the bump has a 3D rebuilding effect on the large-scale separation bubble of the unstarted inlet.Finally,a mass flow correction is performed on the designed bump inlet to increase the mass flow to full airflow capture.The results show that the mass flow rate of the corrected bump inlet reaches up to 0.9993,demonstrating that the correction method is effective.展开更多
BACKGROUND Bivalirudin,a direct thrombin inhibitor,is used in anticoagulation therapies as a substitute for heparin,especially during cardiovascular procedures such as percutaneous coronary intervention.AIM To explore...BACKGROUND Bivalirudin,a direct thrombin inhibitor,is used in anticoagulation therapies as a substitute for heparin,especially during cardiovascular procedures such as percutaneous coronary intervention.AIM To explore the effect of bivalirudin on myocardial microcirculation following an intervention and its influence on adverse cardiac events in elderly patients with acute coronary syndrome(ACS).METHODS In total,165 patients diagnosed with acute myocardial at our hospital between June 2020 and June 2022 were enrolled in this study.From June 2020 to June 2022,elderly patients with ACS with complete data were selected and treated with interventional therapy.The study cohort was randomly divided into a study group(n=80,administered bivalirudin)and a control group(n=85,administered unfractionated heparin).Over a 6-mo follow-up period,differences in emergency processing times,including coronary intervention,cardiac function indicators,occurrence of cardiovascular events,and recurrence rates,were analyzed.RESULTS Significant differences were observed between the study cohorts,with the observation group showing shorter emergency process times across all stages:Emergency classification;diagnostic testing;implementation of coronary intervention;and conclusion of emergency treatment(P<0.05).Furthermore,the left ventricular ejection fraction in the observation group was significantly higher(P<0.05),and the creatine kinase-MB and New York Heart Association scores were CONCLUSION In elderly patients receiving interventional therapy for ACS,bivalirudin administration led to increased activated clotting time achievement rates,enhanced myocardial reperfusion,and reduced incidence of bleeding complications and adverse cardiac events.展开更多
基金supported by the National Key Technologies R&D Program of China for the Eleventh Five-Year Plan Period (Grant No. 2008BAB29B08-02)the Program for the Ministry of Education and State Administration of Foreign Experts Affairs of China (Grant No. B08408)
文摘Flow in tidal rivers periodically propagates upstream or downstream under tidal influence. Hydrodynamic models based on the Saint-Venant equations （the SVN model） are extensively used to model tidal rivers. A force-corrected term expressed as the combination of flow velocity and the change rate of the tidal fevel was developed to represent tidal effects in the SVN model. A momentum equation incorporating with the corrected term was derived based on Newton＇s second law. By combing the modified momentum equation with the continuity equation, an improved SVN model for tidal rivers （the ISVN model） was constructed. The simulation of a tidal reach of the Qiantang River shows that the ISVN model performs better than the SVN model. It indicates that the corrected force derived for tidal effects is reasonable; the ISVN model provides an appropriate enhancement of the SVN model for flow simulation of tidal rivers.
基金the National Natural Science Foundation of China(No.12102470)the Hunan Provincial Innovation Foundation for Postgraduate(No.CX20200082),China。
文摘Transverse pressure gradient(TPG)is one of the key factors influencing the boundary layer airflow diversion in a bump inlet.This paper proposes a novel TPG-based hypersonic bump inlet design method.This method consists of two steps.First,a parametric optimization approach is employed to design a series of 2D inlets with various compression efficiencies.Then,according to the prescribed TPG,the optimized inlets are placed in different osculating planes to generate a 3D bump inlet.This method provides a means to directly control the aerodynamic parameters of the bump rather than the geometric parameters.By performing this method to a hypersonic chin inlet,a long and wide bump surface is formed in the compression wall,which leads to good integration of the bump/inlet.Results show that a part of the near-wall boundary layer flow is diverted by the bump,resulting in a slight decrease in the mass flow but a significant improvement in the total pressure recovery.In addition,the starting ability is significantly improved by adding the bump surface.Analysis reveals that the bump has a 3D rebuilding effect on the large-scale separation bubble of the unstarted inlet.Finally,a mass flow correction is performed on the designed bump inlet to increase the mass flow to full airflow capture.The results show that the mass flow rate of the corrected bump inlet reaches up to 0.9993,demonstrating that the correction method is effective.
文摘BACKGROUND Bivalirudin,a direct thrombin inhibitor,is used in anticoagulation therapies as a substitute for heparin,especially during cardiovascular procedures such as percutaneous coronary intervention.AIM To explore the effect of bivalirudin on myocardial microcirculation following an intervention and its influence on adverse cardiac events in elderly patients with acute coronary syndrome(ACS).METHODS In total,165 patients diagnosed with acute myocardial at our hospital between June 2020 and June 2022 were enrolled in this study.From June 2020 to June 2022,elderly patients with ACS with complete data were selected and treated with interventional therapy.The study cohort was randomly divided into a study group(n=80,administered bivalirudin)and a control group(n=85,administered unfractionated heparin).Over a 6-mo follow-up period,differences in emergency processing times,including coronary intervention,cardiac function indicators,occurrence of cardiovascular events,and recurrence rates,were analyzed.RESULTS Significant differences were observed between the study cohorts,with the observation group showing shorter emergency process times across all stages:Emergency classification;diagnostic testing;implementation of coronary intervention;and conclusion of emergency treatment(P<0.05).Furthermore,the left ventricular ejection fraction in the observation group was significantly higher(P<0.05),and the creatine kinase-MB and New York Heart Association scores were CONCLUSION In elderly patients receiving interventional therapy for ACS,bivalirudin administration led to increased activated clotting time achievement rates,enhanced myocardial reperfusion,and reduced incidence of bleeding complications and adverse cardiac events.
