To test the validity of a theoretical model of aortic valve closure, based upon the observations in a two-dimensional analogue, the effect of some hemodynamic factors on aortic valve behaviour was studied in open-chest dogs. Direct cinematography was used to record aortic valve movements. The ECG, instantaneous ascending aortic blood flow as well as left ventricular and aortic pressures were re...

PURPOSE Ahmed glaucoma valves were implanted into the ciliary sulcus of two patients diagnosed with neovascular glaucoma with favorable outcomes. METHODS The study patients presented to our hospital with ocular pain caused by increased intraocular pressure (IOP). A thorough history was taken, and an ophthalmic examination was performed. RESULTS A 71-year-old male patient and a 57-year-old f...

Aorta is formed in a dynamic environment which gives rise to imbalances between many forces that tend to extend the diameter and length. Furthermore, internal forces tend to resist this extension. Impedance tomography can show this imbalance to stimulate the stenosis of aortic valve, growth of the elastic, collagen and to effectively reduce the stresses in the underlying tissue. In blood flow, ...

Internal pressure waves influence the performance of reciprocating compressors in two ways: Firstly they interact with the valve dynamics and secondly they excite an oscillating moment onto the piston. On the basis of 2-D and 3-D simulations using a commercial CFD code and the experiences of compressor manufacturers a 1-D flow model is introduced. Valve dynamics are described by a modified Cost...

In this study we analyzed both bending and impact stress of the discharge valve of the rotary compressor using a commercial FEM program MSC/NASTRAN and predicted the amount of maximum stress and the location it occurred. We measured the maximum stress of the valve in bolt case compressor using the resistance type strain gages. Good agreement was made by the comparison between the numerical anal...

Abstract Based on the structural principle of existing two-position anti-skid valve for urban rail vehicles, has been modified to increase pressure maintaining position based original only brake and release position, so as upgrade three-position valve. As pressure-maintaining is added, maximum braking force shall be kept far possible under premise control train, shorten distance ensure driving ...

Reed valves in many small compressors arc usually activated automatically by pressure differences across the valve. These valves arc sometime called automatic valves. They have a very simple geometry and construction but they comprise one of the most complicated performance characteristics. The unsteady vibration of the valve reed during the operation requires a proper design. Generally too sti...

The unbalanced barrel pitching system is a typical electro-hydraulic coupling servo control system, the performance of which determines response speed and hit probability vehicle mounted weapon equipment. However, in actual service process, its core component, high precision jet pipe valve, will produce gradual erosion pilot stage’s receivers power throttling edges, induce degradation finally g...