نتایج جستجو برای: velocity pressure
تعداد نتایج: 530938 فیلتر نتایج به سال:
in this paper, the methodology of aircraft air distribution system has been analyzed theoretically and experimentally. to achieve that, ducting pressure loss and air flow throw gaspers calculations has been done for cabin ducts in according to exact location of individual air distribution system in the cabin. the length of gasper air flow was compared with the distance between gasper outlet and...
We propose a new method to derive aortic pressure from peripheral pressure and velocity by using a time domain approach. Peripheral pressure is separated into its forward and backward components, and these components are then shifted with a delay time, which is the ratio of wave speed and distance, and added again to reconstruct aortic pressure. We tested the method on a distributed model of th...
Continuous-wave Doppler echocardiography was used to estimate pulmonary artery pressures by measuring pulmonary regurgitant flow velocity in 21 patients with pulmonary hypertension (mean pulmonary artery pressure greater than or equal to 20 mm Hg) and 24 patients without pulmonary hypertension. The pulmonary regurgitant flow velocity patterns, characterized by a rapid rise in flow velocity imme...
BACKGROUND AND PURPOSE Computational fluid dynamics modeling is useful in the study of the hemodynamic environment of cerebral aneurysms, but patient-specific measurements of boundary conditions, such as blood flow velocity and pressure, have not been previously applied to the study of flow-diverting stents. We integrated patient-specific intravascular blood flow velocity and pressure measureme...
Background & Objective : Several indices have been introduced to estimate arterial stiffness that based on changes in brachial blood pressure. But because of the error resulted by the substitution of brachial blood pressure instead of the other central arteries, such as carotid, it will be very important to present elastic parameter based on the mechanical models without any emphasis on brach...
In this paper, a mathematical model is developed, taking into consideration the slip velocity at the wall of blood vessel of time-dependent Stenosis with unsteady flow through a tube in the presence of a Stenosis. Momentum integral method has been used to evaluate axial velocity and pressure gradient in time dependent Stenosis. Results have also been compared with and without the effect of slip...
Noninvasive evaluation of brachial artery diameter (pulsed Doppler velocimetry) and pulse wave velocity (strain gauge mechanography) was performed in 23 normal subjects and 49 patients with uncomplicated essential hypertension. Pulsatile arterial function was described in terms of derived characteristic impedance and arterial compliance. Compared with normal controls, hypertensive patients had ...
Aim of this study is the assessment of feasibility and clinical usefulness of a new index of stenosis severity, the slope of the instantaneous transstenotic pressure gradient/velocity relationship. Twenty-one patients scheduled for percutaneous revascularization procedures were studied with simultaneous measurement of poststenotic coronary pressure and flow velocity, in basal condition and duri...
The relation of the Doppler transmitral flow velocity profile to left ventricular loading conditions and diastolic properties remains poorly described. We studied seven adult mongrel dogs with an open-chest right heart bypass model in which left atrial pressure, representing preload, was varied by controlling blood flow into the pulmonary artery and left ventricular systolic pressure, represent...
BACKGROUND Lack of high-fidelity simultaneous measurements of pressure and flow velocity distal to a coronary artery stenosis has hampered the study of stenosis pressure drop-velocity (DeltaP-v) relationships in patients. METHODS AND RESULTS A novel 0.014-inch dual-sensor (pressure and Doppler velocity) guidewire was used in 15 coronary lesions to obtain per-beat averages of pressure drop and...
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