With respect to the crest spillway with large unit discharge and low Froude number, the hydraulics of the slit-type energy dissipater at the outlet should be noticed due to the complicated flow regimes. In the present...With respect to the crest spillway with large unit discharge and low Froude number, the hydraulics of the slit-type energy dissipater at the outlet should be noticed due to the complicated flow regimes. In the present paper, some issues about hydraulic characteristics were experimentally investigated by means of five slit-type outlets and four tetrahedrons, including the flow choking, impact to river banks and jet trajectory. The main findings are as follows. The critical Froude number for the flow choking decreases with increasing outlet width of the slit-type energy dissipater. If the flow Froude number is expressed by the parameters just before this energy dissipater, the tetrahedron placed inside the side wall of the outlet could efficiently avoid the flow impact to the river bank of same side, and compared with the jet trajectory of the slit-type energy dissipater, the outlet with tetrahedron has different trajectory trend, i.e., the distance of the jet trajectory decreases with the increase of the water head due to special form of the outlet tetrahedron.展开更多
Background Aortic valve replacement （AVR） improves survival in severe symptomatic aortic stenosis （AS）. Yet, in many patients with severe AS, the timing of AVR remains poorly defined. In particular, it is challeng...Background Aortic valve replacement （AVR） improves survival in severe symptomatic aortic stenosis （AS）. Yet, in many patients with severe AS, the timing of AVR remains poorly defined. In particular, it is challenging in patients with low mean pressure gradient （〈 40 mmHg） and severe AS （aortic valve area （AVA）≤1.0 cm^2） with preserved left ventricular （LV） ejection fraction.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.51179056)
文摘With respect to the crest spillway with large unit discharge and low Froude number, the hydraulics of the slit-type energy dissipater at the outlet should be noticed due to the complicated flow regimes. In the present paper, some issues about hydraulic characteristics were experimentally investigated by means of five slit-type outlets and four tetrahedrons, including the flow choking, impact to river banks and jet trajectory. The main findings are as follows. The critical Froude number for the flow choking decreases with increasing outlet width of the slit-type energy dissipater. If the flow Froude number is expressed by the parameters just before this energy dissipater, the tetrahedron placed inside the side wall of the outlet could efficiently avoid the flow impact to the river bank of same side, and compared with the jet trajectory of the slit-type energy dissipater, the outlet with tetrahedron has different trajectory trend, i.e., the distance of the jet trajectory decreases with the increase of the water head due to special form of the outlet tetrahedron.
文摘Background Aortic valve replacement （AVR） improves survival in severe symptomatic aortic stenosis （AS）. Yet, in many patients with severe AS, the timing of AVR remains poorly defined. In particular, it is challenging in patients with low mean pressure gradient （〈 40 mmHg） and severe AS （aortic valve area （AVA）≤1.0 cm^2） with preserved left ventricular （LV） ejection fraction.
