Valve Action Research Articles

Computer analysis of the effects of valve actions on initial transients in organ flue pipes

Computer measurements have been made of the onset transients of a set of experimental “Principal” organ pipes. The pipes were played individually from a number of valves closely resembling the two most common types of pipe organ valve actions. One action (representative of many electro-pneumatic types) has a small circular valve directly beneath the pipe; the other action (tracker type) consists of a long rectangular valve which admits air into a chamber which feeds the pipe. The analysis was a time-tracking correlation of the fundamental frequency from the time of valve opening through to the steady state. Partials were treated as a quasiharmonic series and analyzed similarly. Steady-state spectra of the same pipe played on different valve actions shows results which are contrary to that reported by some previous researchers. (The pipes and experimental wind chest were donated by the M. P. Moller Co., Hagerstown, MD.)

Construction and evaluation of a hydromechanical simulation facility for the assessment of mitral valve prostheses.

A hydromechanical simulator of the human left heart and systemic circulation system has been built for evaluating the dynamic actions of mitral valve prostheses. The facility includes a transparent and compliant model ventricle pumping into a simulation of the systemic circulation impedance. Transparent materials permit detailed high speed photography of valve action from the left ventricular aspect. This action has been analyzed by digitizing the valve open area and computing the variation of area with time. Additionally, pressures across and flows through the valves have been measured. Comparison has been made between the maximum observed valve open areas and the areas computed using the appropriate pressure and flow measurements substituted in clinically used equations.

A theoretical model for the calculation of large transients in nuclear natural-circulation U-tube steam generators (Digital code UTSG)

A newly developed nonlinear transient model for the calculation of the dynamic behaviour of a vertical natural-circulation U-tube steam generator together with its steam removal system is presented. The steam generator is considered to consist of a heat exchange section, a top plenum, a downcomer region and a steam removal system with a sequence of relief and/or safety valves, isolation, bypass, turbine-trip and turbine-control valves and a steam turbine. Possible perturbations from outside can be: inlet water temperature, inlet water mass flow and system pressure on the primary side, feed water temperature, feed water mass flow and outlet steam mass flow disturbed by actions of the different valves within the steam removal system on the secondary side. Based on this theoretical model the digital code UTSG has been established. Post-calculations of start-up tests at a PWR nuclear power plant simulating perturbations both on the primary and secondary side of the steam generator and similar calculations for the corresponding ATWS-cases will show the efficiency of the code UTSG and the underlying theoretical model.

Selective reinnervation of paralyzed musculature in the head and neck: functioning autotransplantation of the canine larynx.

Previous work has demonstrated the possibility of reinnervation of paralyzed muscle groups in the head and neck by the nerve‐muscle pedicle technique. The ability to transplant a human larynx would be feasible if three problems could be overcome. The first of these is the reestablishment of blood supply, most of which problem has already been solved by the work of Ogura and others. The second is the need to restore function of the vocal cords sufficient to provide the necessary valve action of the larynx. It would then be able to maintain airway, prevent aspiration and restore some use of the voice. Previous work by the present author and others has demonstrated that the nerve‐muscle pedicle technique can theoretically be applied to reinnervate a transplanted larynx. The third problem, that of immunosuppression, remains to be solved.The experiment reported in this paper successfully combines the first two of these criteria in reimplantation of totally excised canine larynges. It follows logically that, if a means of immunosuppression satisfactory for use in human beings who have recently had a malignant process could be found successful human laryngeal transplantation would be a realistic possibility.

Ultrasonic measurement of prosthetic heart valve action.

An in-vitro study has been made of the echo patterns obtained during ultrasonic Time-Motion (T-M) scanning of commonly used prosthetic heart valves. Studies have been undertaken of Starr-Edwards, Beal, and Björk-Shilley valves. From the recorded traces information has been obtained regarding the orientations of the ultrasound beam to the central axes of the valves for which accurate measurements can be made. The orientations have been determined for which the opening and closing times of the valves can be measured to within 20 ms. Characteristics of the T-M trances have been noted which allow the angle between the direction of an ultrasound beam and a central valve axis to be reduced to less than 20 degrees. This makes the error due to angular misalignment of the beam less than --6% when the range of movement of a ball, disc, or flap is being measured. Finally a number of artefacts are considered which can arise when prosthetic valves are examined with ultrasound.

A Field Test and Analytical Study of Intermittent Gas Lift

Abstract A series of controlled experiments of intermittent gas life were carried out in an instrumented well in the Conroe field, Montgomery County, Tex. The well was equipped with seven pressure transducers over the length of the tubing string so that progress of the lifted slug of liquid could be followed up the tubing. Unique to the experimental setup was a surface-controlled, bottom-hole hydraulic valve that allowed for letting a liquid load into the tubing, closing the valve, and isolating the well from the controlled test. Thus, individual intermittent slugs could be studied independent of the well performance. A wide range of slug sizes and injection gas volumes was covered in the 52 test runs.Understanding the action of the gas-life valve is quite important in predicting intermittent-gas-lift performance. Gas-Lift valve action depends somewhat performance. Gas-Lift valve action depends somewhat on the pressure and forces acting upon the stem of the valve. Gas-life literature has assumed that this pressure is equal to the pressure in the casing once pressure is equal to the pressure in the casing once the valve opens. Tests carried out as a result of valve action seen in the instrumented well clearly indicate that this assumption is not valid. Some pressure between the casing pressure and the tubing pressure between the casing pressure and the tubing pressure will exist on the valve stem when the valve pressure will exist on the valve stem when the valve is open; and it is extremely important to be aware of this in predicting valve action. Some design techniques predict the amount of solid liquid slug that will be predict the amount of solid liquid slug that will be brought to the surface and assume that any additional liquid produced in the afterflow of gas will be negligible. It was observed in these tests that a significant portion of the liquid produced at the surface sometimes as much as 50 percent was contributed by this afterflow there will be a considerable discrepancy between predicted and actual results.Liquid recovery from individual runs did not correlate directly with any of the measured parameters. However, it appears that the amount of the liquid slug that is not produced can be correlated with the average gas velocity produced can be correlated with the average gas velocity below the slug. Since the starting slug size is known, the correlation can be used as a predictive technique in intermittent-gas-lift design. The design method has been compared with a field test. Introduction Although intermittent gas lift has been used for artificial lift in oil wells for many years, little concrete technology has been developed for it. Design methods and behavior predictions are as much an art as a science. There have predictions are as much an art as a science. There have been two major attempts to remedy the situation. White et al. attempted to analyze the motion of a finite slug of liquid propelled to the surface by gas injected at high pressure underneath. Supporting their premise by a modicum pressure underneath. Supporting their premise by a modicum of experimentation, they published results in the form of design curves. Brown and Jessen, on the other hand, attempted no analytical solution, but did extensive field testing to develop an empirical foundation for intermittent-gas-lift technology. Unfortunately, there was considerable discrepancy in the results of the two studies.To improve the technology in intermittent gas lift, Shell Oil Co, ran a series of controlled experiments in a gas-life well in the Conroe Field, Montgomery County, Tex. The well instrumentation necessary to carry out the tests is shown in Figs. 1 and 2. (The instrumentation technology was provided by B. C. Sheffield of Shell Development Co.)To predict intermittent-lift behavior, analytical methods are needed to calculate the time rate behavior of the casing gas pressure and volume, the flow of gas through a gas-lift valve, the velocity with which a liquid slug will be raised to the surface by this gas, the amount of liquid that will be produced at the surface and the amount left behind, the pressure gradients during the process, and the time decay pressure gradients during the process, and the time decay curve for the blowdown of gas pressure after the slug has surfaced. None of these functions is independent of the others and all must be considered simultaneously in predicting lift behavior. SPEJ p. 502

The valve action of intensity receptor

The valve action of intensity receptor has the following properties which are essential to an encoder. (1) The response amplitude corresponds to the stimulus intensity in a one-to-one manner. (2) The dynamic ranges of the stimulus intensity and the response amplitude are respectively set and able to move in parallel with their axes. (3) The probability density distribution of the stimulus intensity may be transformed into that of the response amplitude by a stimulus-response relation. Concerning stimulus-response relations, three empirical formulae, i.e. logarithmic, power and tanh log functions, are well known. These formulae can be arranged for the forms to express the above three properties. Then, power and tanh log functions are converted to a logarithmic function as the exponents of them approach zero. From a viewpoint of information theory, the stimulus-response transformation may play a role to improve the probabilistic nature of stimuli in order to make an efficient code for a given channel of sensory fibre.

An hydraulically actuated isolated ventricle.

An apparatus is described that hydraulically actuates an excised dog ventricle. Cam-operated pumps programme flow through the heart valves to approximate in-vivo blood flow. The intact valves and the tortuous ventricular surface provide the authentic mixing influences that are important for indicator dilution studies. The apparatus is also a useful tool for studying heart valve action.

Asymmetric permeability of vectorized membranes

A membrane with composition gradient shows directionality of transport properties if the local permeability is nonideal and can be represented by an irreducible function of location and pressure or concentration. The diffusion current is larger if the side with larger deviation from ideality is exposed to higher pressure or concentration. According to the theory, asymmetriesΔ up to one and even a little more can be achieved. The rapid saturation, however, very soon sets such a low limit toΔ that even with most extreme composition variation of a continuous membrane no efficient valve action can be expected. As a by-product of the investigation one also finds thatFicks first law is inapplicable to permeant diffusion in nonideal membranes.

The Place of Fundoplication in the Treatment of Hiatal Hernia1

Experiences with Nissen's operation of fundoplication by the abdominal route in the treatment of sliding hiatal hernia with reflux are described. Cadaver studies were carried out, and showed that the fundal cuff encircling the lower arsophagus has a positive valve action preventing reflux. Twenty‐eight fundo plications were performed, and 23 of these were followed for periods ranging from six months to three years. These patients are compared with another group of 25 patients treated by other operations. Fundoplication provided complete control of reflux clinically and radiologically in over 95% of cases, and the results were superior to those of the other operations. The sequela of fundoplication were more acceptable to patients than those of vagotomy and pyloroplasty. It proved an effective and safe addition to the repair of the hiatus, and its use is advocated selectively for patients with severe reflux œsophagitis. Some modifications of the technique of operation are suggested.

Practical Hydraulics of Positive Displacement Pumps for High-Pressure Waterflood Installations

Pressure surges, cavitation, and mechanical vibration prevent water Pressure surges, cavitation, and mechanical vibration prevent water injection systems from operating at maximum efficiency. They cause premature failure of the equipment and excessive operating cost. By using premature failure of the equipment and excessive operating cost. By using the engineering principles outlined here, detrimental effects due to inadequate net positive suction head and poor pipe streamlining can be minimized. Introduction As the demand for oil continues its dynamic climb upward, waterflooding will be an increasingly important factor in this country's energy picture. In 1970, waterflooding accounted for 1 of every 4 bbl of oil produced in the U. S. This number will increase to 1 of every 3 bbl by 1980. To meet this demand, many waterfloods are being installed in fields that were considered nonfloodable just a few years ago because of high fluid injection pressures required. Good engineering is imperative in pressures required. Good engineering is imperative in the design of high-pressure installations and will pay for itself many times over in reduced maintenance costs. The purpose of this paper is to present a summary of the technology used in the hydraulic design of positive displacement pump systems for high-pressure waterflood service. Of the three flow regions in a positive displacement high-pressure waterflood systemthe suction, the pump, and the dischargethe pump is the consistent pump, and the dischargethe pump is the consistent element. The manufacturers spend a great deal of time and money on the hydraulics and mechanics and their pumps. To increase volumetric efficiency, the effects of path tortuosity, entrance and exit losses, and fluid compressibility in the design of pump fluid ends are minimized. The elementary principles of fluid mechanics used for the design and analysis of fluid ends can also be used for the inlet and outlet systems. Poor design of suction and discharge piping results in increased pump repair and decreased life of equipment due to overstressing of components by cavitation, excessive pulsation and mechanical vibration. In the design of new systems good sense must be used to avoid these pitfalls and insure the best possible hydraulic and mechanical operating conditions. Positive Displacement Pumps Positive Displacement Pumps The positive displacement pump is the most widely used pump for high-pressure water injection. (In this paper, 2,500 psi and above is considered high pressure.) paper, 2,500 psi and above is considered high pressure.) It is better adapted to high-pressure service than the centrifugal pump because of its high uniform efficiency. (For typical plunger pumps used in oilfield service, the volumetric efficiency is 95 percent and the mechanical efficiency is 90 percent.)A plunger pump, which is the positive displacement pump used in waterflooding, is relatively simple. Fig. pump used in waterflooding, is relatively simple. Fig. 1 shows a cross-section of a typical plunger pump. The fluid is pumped by use of a plunger and a series of valves. The plunger delivers a specific amount of fluid into the discharge line during the discharge stroke. In this part of the operation, the discharge valve is open and the suction valve is closed. During the charge stroke, the specific amount of fluid is taken from the suction line and the valve action is reversed. It is this action of the pump that causes pressure surges. These pressure surges are natural for all positive displacement pumps and if the system is properly positive displacement pumps and if the system is properly designed, should not be troublesome. JPT P. 173

Echocardiographic Diagnosis of Left Atrial Myxoma

As artial myxomata are clinically serious but potentially curable tumors, early diagnosis is desirable. Left atrial myxoma usually produces signs of mitral stenosis and sometimes of mitral regurgitation as well. Although certain diagnostic clues such as variation of the clinical findings with changes in position occasionally arouse the suspicion of an atrial tumor, the diagnosis is usually made either at operation or during cardiac catheterization. 1 Goodwin JF Diagnosis of left atrial myxoma. Lancet. 1963; I: 464 Abstract Scopus (126) Google Scholar , 2 Greenwood FW Profile of atrial myxoma. Amer J Cardiol. 1968; 21: 367 Abstract Full Text PDF PubMed Scopus (124) Google Scholar , 3 Goodwin JF Stanfield CA Steiner RE Clinical features of the left atrial myxoma. Thorax. 1962; 17: 91 Crossref PubMed Scopus (27) Google Scholar , 4 Dembo DH Cowley RA Left atrial thrombosis with ball valve action: report of a case with successful surgical removal. Arch Intern Med. 1964; 114: 139 Crossref PubMed Scopus (6) Google Scholar Several reports have indicated that the diagnosis may be made by reflected ultrasound. 6 Effert VS Dominig E Diagnostik intraaurikularer tumoren und grober thromben mit dem ultrraschall-echoverfahren. Dtsch Med Wschr. 1959; 84: 6 Crossref PubMed Scopus (41) Google Scholar , 7 Schattenberg TT Echocardiographic diagnosis of left atrial myxoma. Mayo Clinic Proc. 1968; 43: 620 PubMed Google Scholar This, however, has not been widely recognized. The purpose of this communication is to report a case of left atrial myxoma in which the correct diagnosis was made by echocardiography and was later confirmed by cineangiography and surgery.

Effects of bradykinin on the pulmonary vascular bed of the intact dog

Intravenous infusion of bradykinin in intact dogs resulted in a significant increase in cardiac output, pulmonary blood volume, pulmonary artery pressure and pulmonary vein pressure and a significant decrease in systemic and total pulmonary vascular resistances. The decrease in total pulmonary vascular resistance was due to dilatation of the pulmonary arterioles, whereas the increase in pulmonary vein pressure was considered to be due to a shift of blood into the pulmonary venous system. The increase in pulmonary vein pressure with no change in left atrial pressure suggested a throttle valve action of the pulmonary veins, probably at the veno-left atrial junction. No evidence was obtained during these experiments to indicate that bradykinin actively dilates the pulmonary veins.

Computer simulation studies of the venous circulation.

An analog computer model of the human cardiovascular system has been set up in which detailed attention is given to the representation of pressure and flow events in the veins, including effects of gravity, collapse, breathing, and the action of venous valves. This model, which includes a control loop for heart rate, was checked against human venous pressure waveforms and against response of the human to tilt-table experiments. These comparisons indicate that the model is valid for the study of postulated venous tone control characteristics; it should also be useful in the study of the mechanisms of venous return and circulatory system response during unusual acceleration conditions.

Physical effects in red blood cell trauma

AbstractRed blood cell damage and destruction are important problems in the use of artificial valves, heart‐lung machines, and other devices which pump or process blood. An experimental study has been made on the mechanism of cell damage. Damage was defined by three types of observations on blood which had been subjected to trauma: (a) release of hemoglobin from cells (hemolysis), (b) morphological changes observed microscopically, and (c) red cell life span studies in rabbits using a Cr51 tagging technique.Three types of physical forces which might be injurious to red cells were studied; shearing stress (of known, constant magnitudes from a concentric cylinder viscometer), pressure variations (from studies in a static pressure cell), and direct impact of solid surfaces (from studies in a device which simulates the seating action of artificial heart valves).The study shows that high shearing stress may be primarily responsible for mechanical cell damage under certain important circumstances. There is a critical shearing stress above which cell damage increases markedly. Much of the cell damage does not appear as an immediate release of hemoglobin. Many cells undergo morphological changes and exhibit shortened average life span in vivo. The morphological changes due to shearing stress are very similar to the changes observed in patients who have hemolytic anemia associated with artificial valves.

Mitral valve action and the mode of ventricular filling.

DURING the past fifty years conflicting experimental evidence has been presented on the mechanism of ventricular filling and its response to exercise1. More recently, interest has been rekindled by the advent of open heart surgery and the routine replacement of diseased mitral valves with artificial prostheses. In particular, the haemodynamic results of mitral valve replacement using ball and disk valves have provided some important evidence about the way in which the ventricle fills and suggest that normally it is inseparable from mitral valve action.

Spectral Component Coupling in Wind Instruments

The input impedance curves of wind instruments generally show a limited number of resonance peaks. These peaks disappear at a frequency set by the bell cutoff or by the high-pass filter action of a series of open tone holes. The playing frequency and spectrum of a wind instrument tone can be correlated with the input impedance at the harmonics of the playing frequency because the spectral components are primarily coupled to the pipe resonances by the nonlinearity of the valving action of the reed. The basic formalism, which has been reported earlier, will be used to explain the observed connection between “rigidity” of pitch in certain wind instruments and the placement of higher pipe resonances. Clarinet throat tones will also be discussed with reference to the number of associated pipe resonance peaks. There are only two of these for the throat tones, while the other notes of the chalumeau register have three or more.

The effects of loading the respiratory pumps on the oxygen consumption of Callionymus lyra.

ABSTRACT A comparative study of the respiration of fishes from different ecological niches has shown that certain species are suited for the study of particular aspects of respiratory function because of their structure and physiological adaptations. In this context the study of the generally less active bottom-living forms has advantages where movements of the fish must be limited by the experimental arrangement. In the case of the dragonet, Callionymus lyra, there is the added advantage that water issuing from the opercular cavities can be readily collected into tubes fixed round the external openings without impairing the action of the opercular valves. These preparations proved of great value in making direct measurements of the ventilation volume under varying conditions (Hughes & Umezawa, 1968a). The relationship between ventilation volume and muscular activity was also studied very conveniently in this species (Hughes & Ballintijn, 1968).

A study of mitral valve action recorded by reflected ultrasound and its application in the diagnosis of mitral stenosis.

The movements of two ultrasound echo signals, believed to arise from the anterior mitral leaflet and from the mitral ring, were studied in 30 normal subjects and in 100 heart-catheterization patients. Fifty patients had proven mitral stenosis. The echo from the anterior mitral leaflet is shown to have a complex pattern of movement. This pattern is analyzed into the opening and closing movements of the leaflet, and the underlying movement transmitted from the mitral ring. In the normal condition, the characteristic feature of leaflet motion is a sharp closing movement that follows the initial opening in diastole. This sharp closing movement is not seen in the presence of mitral stenosis. It is believed that the demonstration of a sustained wide-open poisition of the leaflet in diastole has the same diagnostic significance as the finding of a persistent positive-pressure gradient across the valve. The value of this method in diagnosing the severity of the stenosis is discussed.

Shell Movements of a Wood Boring Bivalve

SOME bivalves of the super-family Adesmacea are known to penetrate wood by means of mechanical action of the shell valves. The process has been described by various authors, the most comprehensive account being that of Miller1 for Teredo. Although rocking movements of the shell valves about a dorso-ventral axis are known to be important in penetration of this substratum2, there seem to be no records for any wood boring bivalve of the type and frequency of the shell movements involved.