Dynamic Pumping Performance of the Hemopump®-A Small Intraventricular Blood Pump

1992 ◽  
Vol 15 (8) ◽  
pp. 493-498 ◽  
Author(s):  
E.E. Kunst ◽  
J.A. Van Alsté
Keyword(s):  
Differential Equation ◽  
Order Differential Equation ◽  
Axial Flow ◽  
Pressure Head ◽  
Blood Pump ◽  
First Order ◽  
Mock Circulation ◽  
Temporary Support ◽  
Axial Flow Pump ◽  
Flow Pump

We studied the pumping characteristics of the Hemopump®, a commercially availabe miniature intraventricular blood pump for temporary support of failing hearts. The Hemopump® is an axial flow pump of which the characteristics can be described by turbomachine theory. Experiments with water and a mock circulation verified that the pumping characteristics of the Hemopump®, in terms of both pressure head and flow as a function of rotational speed, very well can be described by a first order differential equation. The influence of blood with its non-Newtonian character is being investigated

Interrelationship Between the Efficiency Characteristics and the Pressure Head Gradients Among Axial Flow Pumps

1996 ◽  
Author(s):  
Takaharu Tanaka
Keyword(s):  
Cross Section ◽  
Flow Rate ◽  
Axial Flow ◽  
Internal Flow ◽  
Pressure Head ◽  
Design Flow ◽  
Discharge Valve ◽  
Head Gradient ◽  
Axial Flow Pump ◽  
Flow Pump

There is a correlation between the efficiency of the pump to the head produced. On the axial flow pump, whose efficiency characteristic is favorable, the pressure head gradient between the impeller inlet and the outlet sections, at an equivalent flow rate, may become larger than that for the less favorable axial flow pump. This fundamental interrelation may be held in the flow passage regardless to the flow rate whichever they are operated at design or off design flow rate. There may be a direct correlation between the efficiency of an axial flow pump and the ratio of the discharge valve cross section divided by the pipeline cross section. The smaller this ratio is the better the pressure head gradient is for the same flow rates. This ratio may be useful to estimate relative grade of heads, pressure head gradients, internal flow conditions, and efficiency characteristics among axial flow pumps.

scholarly journals An exact expression of positive periodic solution for a first-order singular equation

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Yun Xin ◽  
Xiaoxiao Cui ◽  
Jie Liu
Keyword(s):  
Differential Equation ◽  
Periodic Solution ◽  
Lower Bounds ◽  
Topological Degree ◽  
Order Differential Equation ◽  
Positive Periodic Solution ◽  
Exact Expression ◽  
Upper And Lower Bounds ◽  
Singular Equation ◽  
First Order

Abstract The main purpose of this paper is to obtain an exact expression of the positive periodic solution for a first-order differential equation with attractive and repulsive singularities. Moreover, we prove the existence of at least one positive periodic solution for this equation with an indefinite singularity by applications of topological degree theorem, and give the upper and lower bounds of the positive periodic solution.

scholarly journals Investigation into the Influence of Division Pier on the Internal Flow and Pulsation in the Outlet Conduit of an Axial-Flow Pump

2021 ◽  
Vol 11 (15) ◽  
pp. 6774
Author(s):  
Fan Yang ◽  
Dongjin Jiang ◽  
Tieli Wang ◽  
Pengcheng Chang ◽  
Chao Liu ◽  
...  
Keyword(s):  
Velocity Distribution ◽  
Pressure Pulsation ◽  
Axial Flow ◽  
Hydraulic Loss ◽  
Main Frequency ◽  
Starting Position ◽  
The Difference ◽  
Axial Flow Pump ◽  
Outlet Conduit ◽  
Flow Pump

The outlet conduit is an important construction connecting the outlet of the pump guide vane and the outlet pool; in order to study the hydraulic performance of the straight outlet conduit of the axial-flow pump device, this paper adopts the method of numerical simulation and analyzes the influence of the division pier on the pressure and velocity distribution inside and near the wall of the straight outlet conduit based on three design schemes. Four pressure pulsation measuring points were arranged in the straight outlet conduit, and the low-frequency pulsation characteristic information inside the straight outlet conduit with and without the division pier was extracted by wavelet packet reconstruction. The results show that the addition of a division pier has an effect on the hydraulic loss, near-wall pressure and velocity distribution in the straight outlet conduit. A small high-pressure zone is formed near the wall at the starting position of the division pier, and a large high-speed zone is formed on the left side at the starting position of the division pier. The length of the division pier has no significant effect on the flow distribution of the straight outlet conduit and the pressure and velocity distribution near the wall. Under different working conditions, each monitoring point has the maximum energy in the sub-band (0~31.25 Hz). With the increase of the flow rate, the total pressure energy of the straight outlet conduit decreases gradually. Under each condition, the difference of the energy proportion of the horizontal monitoring points of the straight outlet conduit is small, and the difference of the energy proportion of the two monitoring points at the top and bottom of the outlet channel is relatively large. The energy of the two monitoring points in the straight outlet conduit with a division pier is smaller than that of the two monitoring points in the straight outlet conduit without a division pier. There are differences in the main frequency and the power spectrum corresponding to the main frequency of the monitoring points in the straight outlet conduit, and the reasonable setting of the division pier is conducive to reducing the pressure pulsation of the flow in the straight outlet conduit and is beneficial to the safe and stable operation of the pump device.

Asymptotics for third-order nonlinear differential equations: Non-oscillatory and oscillatory cases

2021 ◽  
pp. 1-19
Author(s):  
Calogero Vetro ◽  
Dariusz Wardowski
Keyword(s):  
Differential Equation ◽  
Differential Equations ◽  
Order Differential Equation ◽  
Nonlinear Differential Equations ◽  
Oscillatory Behavior ◽  
Third Order ◽  
First Order ◽  
Third Order Differential Equation ◽  
Comparison Technique ◽  
First Order Differential Equations

We discuss a third-order differential equation, involving a general form of nonlinearity. We obtain results describing how suitable coefficient functions determine the asymptotic and (non-)oscillatory behavior of solutions. We use comparison technique with first-order differential equations together with the Kusano–Naito’s and Philos’ approaches.

Foetal bypass: concepts and controversies

Perfusion ◽  
1998 ◽  
Vol 13 (2) ◽  
pp. 111-117 ◽  
Author(s):  
Joseph J Sistino
Keyword(s):  
Heart Defects ◽  
Open Heart Surgery ◽  
Axial Flow ◽  
Right Atrial ◽  
Cyclooxygenase Inhibitors ◽  
Pump System ◽  
Maternal Risk ◽  
Valvular Stenosis ◽  
Axial Flow Pump ◽  
Flow Pump

One of the most controversial and challenging surgical undertakings of the next century promises to be foetal cardiac surgery. Animal studies have been underway for several years to gain an understanding of the physiological mechanisms required to achieve this undertaking. Not since the days of crosscirculation has there been a maternal risk associated with open-heart surgery. The diagnosis of congenital heart defects with foetal ultrasound can now be made as early as 12 weeks gestation. Simple cardiac abnormalities, such as valvular stenosis or atresia, alter intracardiac flow patterns and affect normal cardiac chamber development. Without early intervention, these complex lesions often require major surgical reconstruction, beginning in the neonatal period. Foetal cardiac bypass techniques have evolved from the use of roller pumps and bubble oxygenators primed with maternal blood to the use of an axial flow pump incorporated in a right atrial to pulmonary artery or aortic shunt. Because the blood entering the right atrium is oxygenated by the placenta, an oxygenator in the bypass circuit is probably not needed. The low prime axial flow pump system avoids the dilution of the foetus with the maternal adult haemoglobin and improves the outcome. A major focus of research has concentrated on maintenance of placental blood flow with the use of vasodilators and cyclooxygenase inhibitors. Investigation with primates will be necessary to confirm the placental physiology before human operations can be performed. As the foetal bypass challenges are overcome, there is the potential for a reduction in the number of complex cardiac lesions requiring early surgical intervention in the twenty-first century.

scholarly journals WORLD VOLUME SOLITONS OF THE D3-BRANE IN THE BACKGROUND OF (p, q) FIVE-BRANES

2000 ◽  
Vol 15 (28) ◽  
pp. 4477-4498 ◽  
Author(s):  
P. M. LLATAS ◽  
A. V. RAMALLO ◽  
J. M. SÁNCHEZ DE SANTOS
Keyword(s):  
Differential Equation ◽  
Order Differential Equation ◽  
Brane World ◽  
Invariant Solutions ◽  
First Order ◽  
World Volume ◽  
The World ◽  
Energy Bound

We analyze the world volume solitons of a D3-brane probe in the background of parallel (p, q) five-branes. The D3-brane is embedded along the directions transverse to the five-branes of the background. By using the S duality invariance of the D3-brane, we find a first-order differential equation whose solutions saturate an energy bound. The SO(3) invariant solutions of this equation are found analytically. They represent world volume solitons which can be interpreted as formed by parallel (-q, p) strings emanating from the D3-brane world volume. It is shown that these configurations are 1/4 supersymmetric and provide a world volume realization of the Hanany–Witten effect.

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