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Sample records for actual valve timing

  1. VALVE

    DOEpatents

    Arkelyan, A.M.; Rickard, C.L.

    1962-04-17

    A gate valve for controlling the flow of fluid in separate concentric ducts or channels by means of a single valve is described. In one position, the valve sealing discs engage opposed sets of concentric ducts leading to the concentric pipes defining the flow channels to block flow therethrough. In another position, the discs are withdrawn from engagement with the opposed ducts and at the same time a bridging section is interposed therebetween to define concentric paths coextensive with and connecting the opposed ducts to facilitate flow therebetween. A wedge block arrangement is employed with each sealing disc to enable it to engage the ducts. The wedge block arrangement also facilitates unobstructcd withdrawal of the discs out of the intervening space between the sets of ducts. (AEC)

  2. Device for varying engine valve timing

    SciTech Connect

    Hampton, K.

    1988-07-05

    A device is described for angularly displacing a camshaft relative to the crankshaft of an IC engine to vary the engine valve timing, comprising; a hub member; means to attach the hub member to the engine crankshaft; a drive member rotatably mounted on the hub member, and means connecting the drive member in driving relationship with the engine crankshaft; an advancing member; a first means interconnecting the advancing member with the hub member affecting limited axial movement of the advancing member relative to the hub member; a second means interconnecting the advancing member with the drive member which upon axial movement of the advancing member causes limited rotation of the drive member relative to the hub member; an annular means mounted on the hub member, the advancing member mounted on the annular means; coacting meshing means formed in part on the annular means for moving the advancing member axially relative to the hub upon limited rotation of the annular means relative to the hub; and a non-rotational retarder means which when actuated applies a retarding torque to the annular means causing limited rotation of the annular means relative to the hub and thus cause the advancing member to move axially of the hub whereby the drive member is moved a limited angular distance relative to the hub member.

  3. Real-Time Prognostics of a Rotary Valve Actuator

    NASA Technical Reports Server (NTRS)

    Daigle, Matthew

    2015-01-01

    Valves are used in many domains and often have system-critical functions. As such, it is important to monitor the health of valves and their actuators and predict remaining useful life. In this work, we develop a model-based prognostics approach for a rotary valve actuator. Due to limited observability of the component with multiple failure modes, a lumped damage approach is proposed for estimation and prediction of damage progression. In order to support the goal of real-time prognostics, an approach to prediction is developed that does not require online simulation to compute remaining life, rather, a function mapping the damage state to remaining useful life is found offline so that predictions can be made quickly online with a single function evaluation. Simulation results demonstrate the overall methodology, validating the lumped damage approach and demonstrating real-time prognostics.

  4. Valve

    DOEpatents

    Cho, Nakwon

    1980-01-01

    A positive acting valve suitable for operation in a corrosive environment is provided. The valve includes a hollow valve body defining an open-ended bore for receiving two, axially aligned, spaced-apart, cylindrical inserts. One insert, designated the seat insert, terminates inside the valve body in an annular face which lies within plane normal to the axis of the two inserts. An elastomeric O-ring seal is disposed in a groove extending about the annular face. The other insert, designated the wedge insert, terminates inside the valve body in at least two surfaces oppositely inclined with respect to each other and with respect to a plane normal to the axis of the two inserts. An elongated reciprocable gate, movable between the two inserts along a path normal to the axis of the two inserts, has a first flat face portion disposed adjacent and parallel to the annular face of the seat insert. The gate has a second face portion opposite to the first face portion provided with at least two oppositely inclined surfaces for mating with respective inclined surfaces of the wedge insert. An opening is provided through the gate which registers with a flow passage through the two inserts when the valve is open. Interaction of the respective inclined surfaces of the gate and wedge insert act to force the first flat face portion of the gate against the O-ring seal in the seat insert at the limits of gate displacement where it reaches its respective fully open and fully closed positions.

  5. VALIDATION OF SPRING OPERATED PRESSURE RELIEF VALVE TIME TO FAILURE AND THE IMPORTANCE OF STATISTICALLY SUPPORTED MAINTENANCE INTERVALS

    SciTech Connect

    Gross, R; Stephen Harris, S

    2009-02-18

    The Savannah River Site operates a Relief Valve Repair Shop certified by the National Board of Pressure Vessel Inspectors to NB-23, The National Board Inspection Code. Local maintenance forces perform inspection, testing, and repair of approximately 1200 spring-operated relief valves (SORV) each year as the valves are cycled in from the field. The Site now has over 7000 certified test records in the Computerized Maintenance Management System (CMMS); a summary of that data is presented in this paper. In previous papers, several statistical techniques were used to investigate failure on demand and failure rates including a quantal response method for predicting the failure probability as a function of time in service. The non-conservative failure mode for SORV is commonly termed 'stuck shut'; industry defined as the valve opening at greater than or equal to 1.5 times the cold set pressure. Actual time to failure is typically not known, only that failure occurred some time since the last proof test (censored data). This paper attempts to validate the assumptions underlying the statistical lifetime prediction results using Monte Carlo simulation. It employs an aging model for lift pressure as a function of set pressure, valve manufacturer, and a time-related aging effect. This paper attempts to answer two questions: (1) what is the predicted failure rate over the chosen maintenance/ inspection interval; and do we understand aging sufficient enough to estimate risk when basing proof test intervals on proof test results?

  6. Variable valve timing in a homogenous charge compression ignition engine

    DOEpatents

    Lawrence, Keith E.; Faletti, James J.; Funke, Steven J.; Maloney, Ronald P.

    2004-08-03

    The present invention relates generally to the field of homogenous charge compression ignition engines, in which fuel is injected when the cylinder piston is relatively close to the bottom dead center position for its compression stroke. The fuel mixes with air in the cylinder during the compression stroke to create a relatively lean homogeneous mixture that preferably ignites when the piston is relatively close to the top dead center position. However, if the ignition event occurs either earlier or later than desired, lowered performance, engine misfire, or even engine damage, can result. The present invention utilizes internal exhaust gas recirculation and/or compression ratio control to control the timing of ignition events and combustion duration in homogeneous charge compression ignition engines. Thus, at least one electro-hydraulic assist actuator is provided that is capable of mechanically engaging at least one cam actuated intake and/or exhaust valve.

  7. ASME XI stroke time testing of solenoid valves at Connecticut Yankee Station

    SciTech Connect

    Martin, C.W.

    1996-12-01

    Connecticut Yankee Atomic Power Company has developed the capability of measuring the stroke times of AC and DC solenoid valves. This allows the station to measure the stroke time of any solenoid valve in the plant, even those valves which do not have valve stem position indicators. Connecticut Yankee has adapted the ITI MOVATS Checkmate 3 system, using a signal input from a Bruel and Kjaer (B&K) Model 4382 acoustic accelerometer and the Schaumberg Campbell Associates (SCA) Model SCA-1148 dual sensor, which is a combined accelerometer and gaussmeter.

  8. Significant improvements in the area of stroke timing of motor-operated valves for nuclear plants

    SciTech Connect

    Wohld, P.R. ); Newsome, R.C. )

    1990-01-01

    This paper reports on valve stroke timing test equipment developed and tested for use in a nuclear power plant main control room that can provide significant advantages to the user for valve surveillance testing required by the Nuclear Regulatory Commission. The equipment is particularly suitable for Motor-Operated Valves (MOVs) because of its accuracy and repeatability that is necessary to detect the effects of small changes in actuator motor RPM.

  9. From Mouth-to-Mouth to Bag-Valve-Mask Ventilation: Evolution and Characteristics of Actual Devices—A Review of the Literature

    PubMed Central

    Khoury, Abdo; Hugonnot, Sylvère; Cossus, Johan; Desmettre, Thibaut; Sall, Fatimata Seydou; Capellier, Gilles

    2014-01-01

    Manual ventilation is a vital procedure, which remains difficult to achieve for patients who require ventilatory support. It has to be performed by experienced healthcare providers that are regularly trained for the use of bag-valve-mask (BVM) in emergency situations. We will give in this paper, a historical view on manual ventilation's evolution throughout the last decades and describe the technical characteristics, advantages, and hazards of the main devices currently found in the market. Artificial ventilation has developed progressively and research is still going on to improve the actual devices used. Throughout the past years, a brand-new generation of ventilators was developed, but little was done for manual ventilation. Many adverse outcomes due to faulty valve or misassembly were reported in the literature, as well as some difficulties to ensure efficient insufflation according to usual respiratory parameters. These serious incidents underline the importance of BVM system routine check and especially the unidirectional valve reassembly after sterilization, by only experienced and trained personnel. Single use built-in devices may prevent disassembly problems and are safer than the reusable ones. Through new devices and technical improvements, the safety of BVM might be increased. PMID:24971346

  10. Investigation of a rotary valving system with variable valve timing for internal combustion engines: Final technical report

    SciTech Connect

    Cross, P.C.; Hansen, C.N.

    1994-11-18

    The objective of the program was to provide a functional demonstration of the Hansen Rotary Valving System with Variable Valve timing (HRVS/VVT), capable of throttleless inlet charge control, as an alternative to conventional poppet-valves for use in spark ignited internal combustion engines. The goal of this new technology is to secure benefits in fuel economy, broadened torque band, vibration reduction, and overhaul accessibility. Additionally, use of the variable valve timing capability to vary the effective compression ratio is expected to improve multi-fuel tolerance and efficiency. Efforts directed at the design of HRVS components proved to be far more extensive than had been anticipated, ultimately requiring that proof-trial design/development work be performed. Although both time and funds were exhausted before optical or ion-probe types of in-cylinder investigation could be undertaken, a great deal of laboratory data was acquired during the course of the design/development work. This laboratory data is the basis for the information presented in this Final Report.

  11. Model-Based Estimation of Aortic and Mitral Valves Opening and Closing Timings in Developing Human Fetuses.

    PubMed

    Marzbanrad, Faezeh; Kimura, Yoshitaka; Funamoto, Kiyoe; Oshio, Sayaka; Endo, Miyuki; Sato, Naoaki; Palaniswami, Marimuthu; Khandoker, Ahsan H

    2016-01-01

    Electromechanical coupling of the fetal heart can be evaluated noninvasively using doppler ultrasound (DUS) signal and fetal electrocardiography (fECG). In this study, an efficient model is proposed using K-means clustering and hybrid Support Vector Machine-Hidden Markov Model (SVM-HMM) modeling techniques. Opening and closing of the cardiac valves were detected from peaks in the high frequency component of the DUS signal decomposed by wavelet analysis. It was previously proposed to automatically identify the valve motion by hybrid SVM-HMM based on the amplitude and timing of the peaks. However, in the present study, six patterns were identified for the DUS components which were actually variable on a beat-to-beat basis and found to be different for the early gestation (16-32 weeks), compared to the late gestation fetuses (36-41 weeks). The amplitude of the peaks linked to the valve motion was different across the six patterns and this affected the precision of valve motion identification by the previous hybrid SVM-HMM method. Therefore in the present study, clustering of the DUS components based on K-means was proposed and the hybrid SVM-HMM was trained for each cluster separately. The valve motion events were consequently identified more efficiently by beat-to-beat attribution of the DUS component peaks. Applying this method, more than 98.6% of valve motion events were beat-to-beat identified with average precision and recall of 83.4% and 84.2% respectively. It was an improvement compared to the hybrid method without clustering with average precision and recall of 79.0% and 79.8%. Therefore, this model would be useful for reliable screening of fetal wellbeing. PMID:27123499

  12. Internal combustion engine with rotary valve assembly having variable intake valve timing

    DOEpatents

    Hansen, Craig N.; Cross, Paul C.

    1995-01-01

    An internal combustion engine has rotary valves associated with movable shutters operable to vary the closing of intake air/fuel port sections to obtain peak volumetric efficiency over the entire range of speed of the engine. The shutters are moved automatically by a control mechanism that is responsive to the RPM of the engine. A foot-operated lever associated with the control mechanism is also used to move the shutters between their open and closed positions.

  13. Development of an effective valve packing program

    SciTech Connect

    Hart, K.A.

    1996-12-01

    Current data now shows that graphite valve packing installed within the guidance of a controlled program produces not only reliable stem sealing but predictable running loads. By utilizing recent technological developments in valve performance monitoring for both MOV`s and AOV`s, valve packing performance can be enhanced while reducing maintenance costs. Once known, values are established for acceptable valve packing loads, the measurement of actual valve running loads via the current MOV/AOV diagnostic techniques can provide indication of future valve stem sealing problems, improper valve packing installation or identify the opportunity for valve packing program improvements. At times the full benefit of these advances in material and predictive technology remain under utilized due to simple past misconceptions associated with valve packing. This paper will explore the basis for these misconceptions, provide general insight into the current understanding of valve packing and demonstrate how with this new understanding and current valve diagnostic equipment the key aspects required to develop an effective, quality valve packing program fit together. The cost and operational benefits provided by this approach can be significant impact by the: elimination of periodic valve repacking, reduction of maintenance costs, benefits of leak-free valve operation, justification for reduced Post Maintenance Test Requirements, reduced radiation exposure, improved plant appearance.

  14. Valve timing effect on the cooling performance of a 4 K pulse tube cooler

    NASA Astrophysics Data System (ADS)

    Qiu, L. M.; Thummes, G.

    2002-05-01

    Generally, a compressor together with a rotary valve system generates the pressure oscillation in GM-type cryocoolers. The timing of the rotary valve, which is one of the key operating parameters for cryocoolers, determines the relationship between intake and exhaust processes. A systematic investigation of valve timing effects on cooling performance of a two-stage 4 K pulse tube cooler (PTC) is reported. The experiments show that the optimization of valve timing can considerably improve the cooling performance for both stages. For the same PTC, a performance comparison for operation on different compressors with various input powers ranging from 0.5 to 6.0 kW is also presented.

  15. Real-time 3D visualization of cellular rearrangements during cardiac valve formation.

    PubMed

    Pestel, Jenny; Ramadass, Radhan; Gauvrit, Sebastien; Helker, Christian; Herzog, Wiebke; Stainier, Didier Y R

    2016-06-15

    During cardiac valve development, the single-layered endocardial sheet at the atrioventricular canal (AVC) is remodeled into multilayered immature valve leaflets. Most of our knowledge about this process comes from examining fixed samples that do not allow a real-time appreciation of the intricacies of valve formation. Here, we exploit non-invasive in vivo imaging techniques to identify the dynamic cell behaviors that lead to the formation of the immature valve leaflets. We find that in zebrafish, the valve leaflets consist of two sets of endocardial cells at the luminal and abluminal side, which we refer to as luminal cells (LCs) and abluminal cells (ALCs), respectively. By analyzing cellular rearrangements during valve formation, we observed that the LCs and ALCs originate from the atrium and ventricle, respectively. Furthermore, we utilized Wnt/β-catenin and Notch signaling reporter lines to distinguish between the LCs and ALCs, and also found that cardiac contractility and/or blood flow is necessary for the endocardial expression of these signaling reporters. Thus, our 3D analyses of cardiac valve formation in zebrafish provide fundamental insights into the cellular rearrangements underlying this process.

  16. A method for real-time in vitro observation of cavitation on prosthetic heart valves.

    PubMed

    Zapanta, C M; Liszka, E G; Lamson, T C; Stinebring, D R; Deutsch, S; Geselowitz, D B; Tarbell, J M

    1994-11-01

    A method for real-time in vitro observation of cavitation on a prosthetic heart valve has been developed. Cavitation of four blood analog fluids (distilled water, aqueous glycerin, aqueous polyacrylamide, and aqueous xanthan gum) has been documented for a Medtronic/Hall prosthetic heart valve. This method employed a Penn State Electrical Ventricular Assist Device in a mock circulatory loop that was operated in a partial filling mode associated with reduced atrial filling pressure. The observations were made on a valve that was located in the mitral position, with the cavitation occurring on the inlet side after valve closure on every cycle. Stroboscopic videography was used to document the cavity life cycle. Bubble cavitation was observed on the valve occluder face. Vortex cavitation was observed at two locations in the vicinity of the valve occluder and housing. For each fluid, cavity growth and collapse occurred in less than one millisecond, which provides strong evidence that the cavitation is vaporous rather than gaseous. The cavity duration time was found to decrease with increasing atrial pressure at constant aortic pressure and beat rate. The area of cavitation was found to decrease with increasing delay time at a constant aortic pressure, atrial pressure, and beat rate. Cavitation was found to occur in each of the fluids, with the most cavitation seen in the Newtonian fluids (distilled water and aqueous glycerin). PMID:7869722

  17. Magnetic timing valves for fluid control in paper-based microfluidics.

    PubMed

    Li, Xiao; Zwanenburg, Philip; Liu, Xinyu

    2013-07-01

    Multi-step analytical tests, such as an enzyme-linked immunosorbent assay (ELISA), require delivery of multiple fluids into a reaction zone and counting the incubation time at different steps. This paper presents a new type of paper-based magnetic valves that can count the time and turn on or off a fluidic flow accordingly, enabling timed fluid control in paper-based microfluidics. The timing capability of these valves is realized using a paper timing channel with an ionic resistor, which can detect the event of a solution flowing through the resistor and trigger an electromagnet (through a simple circuit) to open or close a paper cantilever valve. Based on this principle, we developed normally-open and normally-closed valves with a timing period up to 30.3 ± 2.1 min (sufficient for an ELISA on paper-based platforms). Using the normally-open valve, we performed an enzyme-based colorimetric reaction commonly used for signal readout of ELISAs, which requires a timed delivery of an enzyme substrate to a reaction zone. This design adds a new fluid-control component to the tool set for developing paper-based microfluidic devices, and has the potential to improve the user-friendliness of these devices.

  18. Real-time imaging required for optimal echocardiographic assessment of aortic valve calcification

    PubMed Central

    Yousry, Mohamed; Rickenlund, Anette; Petrini, Johan; Gustavsson, Tomas; Prahl, Ulrica; Liska, Jan; Eriksson, Per; Franco-Cereceda, Anders; Eriksson, Maria J; Caidahl, Kenneth

    2012-01-01

    Introduction Aortic valve calcification (AVC), even without haemodynamic significance, may be prognostically import as an expression of generalized atherosclerosis, but techniques for echocardiographic assessment are essentially unexplored. Methods Two-dimensional (2D) echocardiographic recordings (Philips IE33) of the aortic valve in short-axis and long-axis views were performed in 185 consecutive patients within 1 week before surgery for aortic stenosis (n = 109, AS), aortic regurgitation (n = 61, AR), their combination (n = 8) or dilation of the ascending aorta (n = 7). The grey scale mean (GSMn) of the aortic valve in an end-diastolic short-axis still frame was measured. The same frame was scored visually 1–5 as indicating that the aortic valve was normal, thick, or had mild, moderate or severe calcification. The visual echodensity of each leaflet was determined real time applying the same 5-grade scoring system for each leaflet, and the average for the whole valve was calculated. Finally, a similar calcification score for the whole valve based on inspection and palpation by the surgeon was noted. Results Visual assessment of real-time images using the proposed scoring system showed better correlation with the surgical evaluation of the degree of valve calcification (r = 0·83, P<0·001) compared to evaluation of stop frames by visual assessment (r = 0·66, P<0·001) or the GSMn score (r = 0·64, P<0·001). High inter- and intra-observer correlations were observed for real-time visual score (both intraclass correlation coefficient = 0·93). Conclusion Real-time evaluation of the level of AVC is superior to using stop frames assessed either visually or by dedicated computer grey scale measurement software. PMID:23031068

  19. Pneumatic shutoff and time-delay valve operates at controlled rate

    NASA Technical Reports Server (NTRS)

    Horning, J. L.; Tomlinson, L. E.

    1966-01-01

    Shutoff and time delay valve, which incorporates a metering spool that moves at constant velocity under pneumatic pressure and spring compression, increases fluid-flow area at a uniform rate. Diaphragm areas, control cavity volume, and bleed-orifice size may be varied to give any desired combination of time delay and spool travel time.

  20. Testing two temporal upscaling schemes for the estimation of the time variability of the actual evapotranspiration

    NASA Astrophysics Data System (ADS)

    Maltese, A.; Capodici, F.; Ciraolo, G.; La Loggia, G.

    2015-10-01

    Temporal availability of grapes actual evapotranspiration is an emerging issue since vineyards farms are more and more converted from rainfed to irrigated agricultural systems. The manuscript aims to verify the accuracy of the actual evapotranspiration retrieval coupling a single source energy balance approach and two different temporal upscaling schemes. The first scheme tests the temporal upscaling of the main input variables, namely the NDVI, albedo and LST; the second scheme tests the temporal upscaling of the energy balance output, the actual evapotranspiration. The temporal upscaling schemes were implemented on: i) airborne remote sensing data acquired monthly during a whole irrigation season over a Sicilian vineyard; ii) low resolution MODIS products released daily or weekly; iii) meteorological data acquired by standard gauge stations. Daily MODIS LST products (MOD11A1) were disaggregated using the DisTrad model, 8-days black and white sky albedo products (MCD43A) allowed modeling the total albedo, and 8-days NDVI products (MOD13Q1) were modeled using the Fisher approach. Results were validated both in time and space. The temporal validation was carried out using the actual evapotranspiration measured in situ using data collected by a flux tower through the eddy covariance technique. The spatial validation involved airborne images acquired at different times from June to September 2008. Results aim to test whether the upscaling of the energy balance input or output data performed better.

  1. Effects of decreasing inspiratory times during simulated bag-valve-mask ventilation.

    PubMed

    von Goedecke, Achim; Bowden, Kevin; Wenzel, Volker; Keller, Christian; Gabrielli, Andrea

    2005-03-01

    During CPR, an inspiratory time of 2 s is recommended when the airway is unprotected; indicating that approximately 30% of the resuscitation attempt is spent on ventilation, but not on chest compressions. Since survival rates may not decrease when ventilation levels are relatively low, and uninterrupted chest compressions with a constant rate of approximately 100/min have been shown to be lifesaving, it may be beneficial to cut down the time spent on ventilation, and instead, increase the time for chest compressions. In an established bench model of a simulated unprotected airway, we evaluated if inspiratory time can be decreased from 2 to 1 s at different lower oesophageal sphincter pressure (LOSP) levels during ventilation with a bag-valve-mask device. In comparison with an inspiratory time of 2 s, 1 s resulted in significantly (p < 0.001) higher peak airway pressure and peak inspiratory flow rate, while lung tidal volumes at all LOSP levels were clinically comparable. Neither ventilation strategy produced stomach inflation at 20 cmH2O LOSP, and 1 s versus 2 s inspiratory time did not produce significantly higher (mean +/- S.D.) stomach inflation at 15 (8 +/-9 ml versus 0 +/- 0 ml; p < 0.01) and 10 cmH2O LOSP (69 +/- 20 ml versus 34 +/- 18 ml; p < 0.001), and significantly lower stomach inflation at 5 cmH2O LOSP (219 +/- 16 ml versus 308 +/- 21 ml; p < 0.001) per breath. Total cumulative stomach inflation volume over constantly decreasing LOSP levels with an inspiratory time of 2 s versus 1 s was higher (6820 ml versus 5920 ml). In conclusion, in this model of a simulated unprotected airway, a reduction of inspiratory time from 2 to 1 s resulted in a significant increase of peak airway pressure and peak inspiratory flow rate, while lung tidal volumes remained clinically comparable (up to approximately 15% difference), but statistically different due to the precise measurements. Theoretically, this may increase the time available for, and consequently the actual

  2. A microfluidic timer for timed valving and pumping in centrifugal microfluidics.

    PubMed

    Schwemmer, F; Zehnle, S; Mark, D; von Stetten, F; Zengerle, R; Paust, N

    2015-03-21

    Accurate timing of microfluidic operations is essential for the automation of complex laboratory workflows, in particular for the supply of sample and reagents. Here we present a new unit operation for timed valving and pumping in centrifugal microfluidics. It is based on temporary storage of pneumatic energy and time delayed sudden release of said energy. The timer is loaded at a relatively higher spinning frequency. The countdown is started by reducing to a relatively lower release frequency, at which the timer is released after a pre-defined delay time. We demonstrate timing for 1) the sequential release of 4 liquids at times of 2.7 s ± 0.2 s, 14.0 s ± 0.5 s, 43.4 s ± 1.0 s and 133.8 s ± 2.3 s, 2) timed valving of typical assay reagents (contact angles 36-78°, viscosities 0.9-5.6 mPa s) and 3) on demand valving of liquids from 4 inlet chambers in any user defined sequence controlled by the spinning protocol. The microfluidic timer is compatible to all wetting properties and viscosities of common assay reagents and does neither require assistive equipment, nor coatings. It can be monolithically integrated into a microfluidic test carrier and is compatible to scalable fabrication technologies such as thermoforming or injection molding. PMID:25648105

  3. Depressurization valve

    DOEpatents

    Skoda, G.I.

    1989-03-28

    A depressurization valve for use in relieving completely the pressure in a simplified boiling water reactor is disclosed. The normally closed and sealed valve is provided with a valve body defining a conduit from an outlet of a manifold from the reactor through a valve seat. A closing valve disk is configured for fitting to the valve seat to normally close the valve. The seat below the disk is provided with a radially extending annulus extending a short distance into the aperture defined by the seat. The disk is correspondingly provided with a longitudinally extending annulus that extends downwardly through the aperture defined by the seat towards the high pressure side of the valve body. A ring shaped membrane is endlessly welded to the seat annulus and to the disk annulus. The membrane is conformed over the confronted surface of the seat and disk in a C-sectioned configuration to seal the depressurization valve against the possibility of weeping. The disk is held to the closed position by an elongate stem extending away from the high pressure side of the valve body. The stem has a flange configured integrally to the stem for bias by two springs. The first spring acts from a portion of the housing overlying the disk on the stem flange adjacent the disk. This spring urges the stem and attached disk away from the seat and thus will cause the valve to open at any pressure. A second spring-preferably of the Belleville variety-acts on a latch plate surrounding and freely moving relative to the end of the stem. This second spring overcomes the bias of the first spring and any pressure acting upon the disk. This Belleville spring maintains through its spring force the valve in the closed position. At the same time, the latch plate with its freedom of movement relative to the stem allows the stem to thermally expand during valve temperature excursion.

  4. Modelling bulk surface resistance from MODIS time series data to estimate actual regional evapotranspiration

    NASA Astrophysics Data System (ADS)

    Autovino, Dario; Minacapilli, Mario; Provenzano, Giuseppe

    2015-04-01

    Estimation of actual evapotraspiration by means of Penman-Monteith (P-M) equation requires the knowledge of the so-called 'bulk surface resistance', rc,act, representing the vapour flow resistance through the transpiring crop and evaporating soil surface. The accurate parameterization of rc,act still represents an unexploited topic, especially in the case of heterogeneous land surface. In agro-hydrological applications, the P-M equation commonly used to evaluate reference evapotranspiration (ET0) of a well-watered 'standardized crop' (grass or alfalfa), generally assumes for the bulk surface resistance a value of 70 s m-1. Moreover, specific crop coefficients have to be used to estimate maximum and/or actual evapotranspiration based on ET0. In this paper, a simple procedure for the indirect estimation of rc,act as function of a vegetation index computed from remote acquisition of Land Surface Temperature (LST), is proposed. An application was carried out in an irrigation district located near Castelvetrano, in South-West of Sicily, mainly cultivated with olive groves, in which actual evapotranspiration fluxes were measured during two years (2010-2011) by an Eddy Covariance flux tower (EC). Evapotranspiration measurements allowed evaluating rc,actbased on the numerical inversion of the P-M equation. In the same study area, a large time series of MODIS LST data, characterized by a spatial resolution of 1x1 km and a time step of 8-days, was also acquired for the period from 2000 to 2014. A simple Vegetation Index Temperatures (VTI), with values ranging from 0 to 1, was computed using normalized LST values. Evapotranspiration fluxes measured in 2010 were used to calibrate the relationship between rc,act and VTI, whereas data from 2011 were used for its validation. The preliminary results evidenced that, for the considered crop, an almost constant value of rc,act, corresponding to about 250 s m-1, can be considered typical of periods in which the crop is well

  5. [A new approach to the tricuspid valve in Ebstein's anomaly by real time 3D echocardiography].

    PubMed

    Taktak, A; Acar, P; Dulac, Y; Abadir, S; Chilon, T; Roux, D; Glock, Y; Fournial, G

    2005-05-01

    Ebstein's anomaly affects the tricuspid valve with a large range of anatomical forms. Successful tricuspid valvuloplasty depends mainly on the ability to mobilise the leaflets. Evaluation of the leaflet surface is difficult with 2D echocardiography whereas 3D echocardiography provides intracardiac views of the valve. The authors used this method in 10 patients with 3 modes of imaging: biplane, real time and total volume. The study population (age: 1 day to 30 years) included: 1 prenatal diagnosis, 1 neonate with refractory cyanosis, 5 patients with mild tricuspid regurgitation, 3 patients with severe tricuspid regurgitation, 2 of whom underwent valvuloplasty. 3D echocardiography was disappointing in the foetus and neonate because of poor spatial resolution. The ventricular view of the tricuspid valve in older children and adults allowed analysis of tricuspid leaflet coaptation and of the mechanism of regurgitation. The commissures and leaflet surfaces were assessed. The results of surgical valvuloplasty could be evaluated by 3D echocardiography. 3D echocardiography is now transthoracic and a real time investigation. Technical advances are required before it comes into routine usage: a more manoeuvrable matricial probe (integrating pulsed and continuous wave Doppler) and larger volume real time 3D imaging with better resolution. Its role in the assessment of Ebstein's anomaly should be evaluated in a larger series of patients. PMID:15966604

  6. Pacing strategy in simulated cycle time-trials is based on perceived rather than actual distance.

    PubMed

    Nikolopoulos, V; Arkinstall, M J; Hawley, J A

    2001-06-01

    This study determined the pacing strategies and performance responses of six well-trained cyclists/triathletes (peak O2 uptake 66.4+/-3.7 ml x kg(-1) x min(-1), mean+/-SD) during seven simulated time-trials (TT) conducted on a wind-braked cycle ergometer. All subjects first performed a 40 km familiarisation ride (TT1). They were then informed they would be riding a further four 40 km TT for the purpose of a reliability study. Instead, the actual distances ridden for the next three TT were a random order of 34 (TT2), 40 (TT3) and 46 km (TT4). The only feedback given to subjects during TT1-4 was the percentage distance of that ride remaining. During a further 40 km TT (TT5) subjects were allowed to view their heart rate (HR) responses throughout the ride. Despite the significantly different performance times across the three distances (47:23+/-4:23 vs 55:57+/-3:24 vs 65:41+/-3:56 min for the 34, 40 and 46 km respectively, P<0.001), average power output (296+/-48 vs 294+/-48 vs 286+/-40 W) and HR (173+/-11 vs 174+/-12 vs 173+/-12 beats x min(-1)) were similar. The true nature of the first part of the study was then revealed to subjects who subsequently completed an additional 34 km and 46 km TT TT6-7) in which the actual and perceived distance ridden was the same. Power output and HR responses were similar for both unknown (TT2 and TT6) and known (TT4 and TT7) rides for both distances: 296+/-48 vs 300+/-55 W and 173+/-11 vs 177+/-11 beats x min(-1) (34 km) and 286+/-40 vs 273+/-42 W and 173+/-12 vs 174+/-12 beats x min(-1) (46 km). In conclusion, well-trained cyclists rode at similar power outputs and HR during time trials they perceived to be the same distance, but which varied in actual distance from 34 to 46 km.

  7. Indium-111 labeled platelet survival time studies in patients with prosthetic heart valves

    SciTech Connect

    Martinovitch, U.; Carrick, P.; Lieberman, L.M.

    1985-05-01

    Platelet survival time (PST) studies are useful to demonstrate whether or not patients with prosthetic heart valves have normal or shortened PST. During treatment for recurrent TIAs the PST will signal whether the patient is returning towards a normal PST. Using Indium-111 labeled platelets (ILP) the authors studied 10 patients suffering recurrent TIAs after prosthetic valve surgery to determine whether low dose aspirin increased their PST toward normal and whether the treatment had a beneficial effect on their TIA episodes. The authors conclude that low dose aspirin therapy as studied by ILP has no beneficial effect on PST or in preventing recurrent TIA. ILP is an important technique that allows the physician to identify those patients with shortened PST and to determine response to therapy.

  8. A hybrid disturbance rejection control solution for variable valve timing system of gasoline engines.

    PubMed

    Xie, Hui; Song, Kang; He, Yu

    2014-07-01

    A novel solution for electro-hydraulic variable valve timing (VVT) system of gasoline engines is proposed, based on the concept of active disturbance rejection control (ADRC). Disturbances, such as oil pressure and engine speed variations, are all estimated and mitigated in real-time. A feed-forward controller was added to enhance the performance of the system based on a simple and static first principle model, forming a hybrid disturbance rejection control (HDRC) strategy. HDRC was validated by experimentation and compared with an existing manually tuned proportional-integral (PI) controller. The results show that HDRC provided a faster response and better tolerance of engine speed and oil pressure variations.

  9. Time-dependent biaxial mechanical behavior of the aortic heart valve leaflet.

    PubMed

    Stella, John A; Liao, Jun; Sacks, Michael S

    2007-01-01

    Despite continued progress in the treatment of aortic valve (AV) disease, current treatments continue to be challenged to consistently restore AV function for extended durations. Improved approaches for AV repair and replacement rests upon our ability to more fully comprehend and simulate AV function. While the elastic behavior the AV leaflet (AVL) has been previously investigated, time-dependent behaviors under physiological biaxial loading states have yet to be quantified. In the current study, we performed strain rate, creep, and stress-relaxation experiments using porcine AVL under planar biaxial stretch and loaded to physiological levels (60 N/m equi-biaxial tension), with strain rates ranging from quasi-static to physiologic. The resulting stress-strain responses were found to be independent of strain rate, as was the observed low level of hysteresis ( approximately 17%). Stress relaxation and creep results indicated that while the AVL exhibited significant stress relaxation, it exhibited negligible creep over the 3h test duration. These results are all in accordance with our previous findings for the mitral valve anterior leaflet (MVAL) [Grashow, J.S., Sacks, M.S., Liao, J., Yoganathan, A.P., 2006a. Planar biaxial creep and stress relaxatin of the mitral valve anterior leaflet. Annals of Biomedical Engineering 34 (10), 1509-1518; Grashow, J.S., Yoganathan, A.P., Sacks, M.S., 2006b. Biaxial stress-stretch behavior of the mitral valve anterior leaflet at physiologic strain rates. Annals of Biomedical Engineering 34 (2), 315-325], and support our observations that valvular tissues are functionally anisotropic, quasi-elastic biological materials. These results appear to be unique to valvular tissues, and indicate an ability to withstand loading without time-dependent effects under physiologic loading conditions. Based on a recent study that suggested valvular collagen fibrils are not intrinsically viscoelastic [Liao, J., Yang, L., Grashow, J., Sacks, M.S., 2007

  10. Education and Decision Making at the Time of Triptan Prescribing: Patient Expectations vs Actual Practice

    PubMed Central

    Mathew, Paul G.; Pavlovic, Jelena M.; Lettich, Alyssa; Wells, Rebecca E.; Robertson, Carrie E.; Mullin, Kathleen; Charleston, Larry; Dodick, David W.; Schwedt, Todd J.

    2014-01-01

    Background Optimizing patient satisfaction with their medical care and maximizing patient adherence with treatment plans requires an understanding of patient preferences regarding education and their role in decision making when treatments are prescribed. Objective To assess the congruence between patient expectations and actual practice regarding education and decision making at the time a triptan is prescribed. Methods This multicenter cross-sectional survey was performed by headache fellow members of the American Headache Society Headache Fellows Research Consortium at their respective tertiary care headache clinics. Migraine patients who were new patients to the headache clinic and who were current triptan users (use within prior 3 months and for ≥1 year) or past triptan users (no use within 6 months; prior use within 2 years) completed questionnaires that assessed the education they received and their role in decision making at the time a triptan was first prescribed as well as their desire for education and participation in decision making when a triptan is prescribed. Results Consistent with patient preference, most participants received the majority of their education about the triptan from the prescriber's office (70.2%). In descending rank order, participants most desired to be informed about how to decide if a triptan should be taken, when during the course of migraine a triptan should be taken, possible side effects, cost, and how to obtain refills. Regarding side effects, most participants preferred to receive education about the most common side effects of a triptan rather than addressing all possible side effects. Regarding triptan dosing, participants desired to be informed in descending order of importance about taking other medications with triptans, how many doses can be taken for each migraine, how many doses can be taken each week/month, what to do if the triptan does not work, and the triptan mechanism of action. The vast majority of

  11. Time interval moderates the relationship between psyching-up and actual sprint performance.

    PubMed

    Hammoudi-Nassib, Sarra; Chtara, Moktar; Nassib, Sabri; Briki, Walid; Hammoudi-Riahi, Sabra; Tod, David; Chamari, Karim

    2014-11-01

    This study attempted to test whether the strongest effect of psyching-up (PU) strategy on actual sprint performance can be observed when the strategy is used immediately (or almost) before performance compared with when there is a delay between PU and performance. To do so, 16 male sprinters (age, 20.6 ± 1.3 years; body mass, 77.5 ± 7.1 kg; height, 180.8 ± 5.6 cm) were enrolled in a counterbalanced experimental design in which participants were randomly assigned to 10 sessions (2 [Experimental Condition: imagery vs. distraction] × 5 [Time Intervals: no interval, 1 minute, 2 minutes, 3 minutes, and 5 minutes]). Before performing the experimental tasks, participants rated: (a) the Hooper index, (b) their degree of self-confidence, and (c) after the completion of the experimental test; they rated their perceived effort. Findings showed that the imagery significantly improved sprint performance. Specifically, the imagery enhanced performance on the phase of acceleration (0-10 m) and on the overall sprint (0-30 m) when used immediately before performance and at 1- and 2-minute intervals but not for 3- and 5-minute intervals. These findings support the hypothesis that the potential effect of the PU strategy on performance vanishes over time. The pre-experimental task Hooper and self-efficacy indexes did not change across the 10 experimental sessions, reinforcing the view that the observed performance changes were directly caused by the experimental manipulation and not through any altered status of the athletes (self-efficacy, fatigue/recovery, and stress). The potential mechanisms underlying such a process and practical applications are discussed.

  12. Depressurization valve

    DOEpatents

    Skoda, George I.

    1989-01-01

    A depressurization valve for use in relieving completely the pressure in a simplified boiling water reactor is disclosed. The normally closed and sealed valve is provided with a valve body defining a conduit from an outlet of a manifold from the reactor through a valve seat. A closing valve disk is configured for fitting to the valve seat to normally close the valve. The seat below the disk is provided with a radially extending annulus extending a short distance into the aperture defined by the seat. The disk is correspondingly provided with a longitudinally extending annulus that extends downwardly through the aperture defined by the seat towards the high pressure side of the valve body. A ring shaped membrane is endlessly welded to the seat annulus and to the disk annulus. The membrane is conformed over the confronted surface of the seat and disk in a C-sectioned configuration to seal the depressurization valve against the possibility of weeping. The disk is held to the closed position by an elongate stem extending away from the high pressure side of the valve body. The stem has a flange configured integrally to the stem for bias by two springs. The first spring acts from a portion of the housing overlying the disk on the stem flange adjacent the disk. This spring urges the stem and attached disk away from the seat and thus will cause the valve to open at any pressure. A second spring--preferably of the Belleville variety--acts on a latch plate surrounding and freely moving relative to the end of the stem. This second spring overcomes the bias of the first spring and any pressure acting upon the disk. This Belleville spring maintains through its spring force the valve in the closed position. At the same time, the latch plate with its freedom of movement relative to the stem allows the stem to thermally expand during valve temperature excursion. The latch plate in surrounding the stem is limited in its outward movement by a boss attached to the stem at the end of

  13. Combustion, Control, and Fuel Effects in a Spark Assisted HCCI Engine Equipped with Variable Valve Timing

    SciTech Connect

    Bunting, Bruce G

    2006-01-01

    Widespread implementation of homogeneous charge compression ignition (HCCI) engines is presently hindered by stability, control, and load range issues. Although the operable HCCI speed/load range is expanding, it is likely that the initial HCCI engines will rely on conventional combustion for part of the operating cycle. In the present study, we have investigated the role of fuel properties and chemistry on the operation of a spark-assisted gasoline HCCI engine. The engine employed is a single cylinder, 500 cc, port fuel injected research engine, operating near lambda = 1.0 and equipped with hydraulic variable valve actuation. HCCI is initiated by early exhaust valve closing to retain exhaust in the cylinder, thereby increasing the cylinder gas temperature. This is also referred to as a 'negative overlap' strategy. A total of 10 custom blended gasolines and three different batches of indolene from two suppliers were run at 5 speed-load combinations and performance was characterized by timing sweeps. Within the quality of the data set, we can say the all fuels provided equivalent combustion and performance characteristics when compared at the same combustion phasing. The fuels did, however, require different degrees of retained exhaust as measured by exhaust valve closing angle to achieve the same combustion phasing. Fuels with higher octane sensitivity were found to ignite more easily or more quickly and to burn more quickly than fuels with lower octane sensitivity. This is an expected result since the engine is naturally aspirated and operates with high compression temperatures due to the high retained exhaust fraction and recompression.

  14. Molecular Analysis of Oral Bacteria in Heart Valve of Patients With Cardiovascular Disease by Real-Time Polymerase Chain Reaction

    PubMed Central

    Oliveira, Francisco Artur Forte; Forte, Clarissa Pessoa Fernandes; Silva, Paulo Goberlânio de Barros; Lopes, Camile B.; Montenegro, Raquel Carvalho; dos Santos, Ândrea Kely Campos Ribeiro; Sobrinho, Carlos Roberto Martins Rodrigues; Mota, Mário Rogério Lima; Sousa, Fabrício Bitu; Alves, Ana Paula Negreiros Nunes

    2015-01-01

    Abstract Structural deficiencies and functional abnormalities of heart valves represent an important cause of cardiovascular morbidity and mortality, and a number of diseases, such as aortic stenosis, have been recently associated with infectious agents. This study aimed to analyze oral bacteria in dental plaque, saliva, and cardiac valves of patients with cardiovascular disease. Samples of supragingival plaque, subgingival plaque, saliva, and cardiac valve tissue were collected from 42 patients with heart valve disease. Molecular analysis of Streptococcus mutans, Prevotella intermedia, Porphyromonas gingivalis, and Treponema denticola was performed through real-time PCR. The micro-organism most frequently detected in heart valve samples was the S. mutans (89.3%), followed by P. intermedia (19.1%), P. gingivalis (4.2%), and T. denticola (2.1%). The mean decayed, missing, filled teeth (DMFT) was 26.4 ± 6.9 (mean ± SD), and according to the highest score of periodontal disease observed for each patient, periodontal pockets > 4 mm and dental calculus were detected in 43.4% and 34.7% of patients, respectively. In conclusion, oral bacteria, especially S. mutans, were found in the cardiac valve samples of patients with a high rate of caries and gingivitis/periodontitis. PMID:26632711

  15. Molecular Analysis of Oral Bacteria in Heart Valve of Patients With Cardiovascular Disease by Real-Time Polymerase Chain Reaction.

    PubMed

    Oliveira, Francisco Artur Forte; Forte, Clarissa Pessoa Fernandes; Silva, Paulo Goberlânio de Barros; Lopes, Camile B; Montenegro, Raquel Carvalho; Santos, Ândrea Kely Campos Ribeiro Dos; Sobrinho, Carlos Roberto Martins Rodrigues; Mota, Mário Rogério Lima; Sousa, Fabrício Bitu; Alves, Ana Paula Negreiros Nunes

    2015-11-01

    Structural deficiencies and functional abnormalities of heart valves represent an important cause of cardiovascular morbidity and mortality, and a number of diseases, such as aortic stenosis, have been recently associated with infectious agents. This study aimed to analyze oral bacteria in dental plaque, saliva, and cardiac valves of patients with cardiovascular disease. Samples of supragingival plaque, subgingival plaque, saliva, and cardiac valve tissue were collected from 42 patients with heart valve disease. Molecular analysis of Streptococcus mutans, Prevotella intermedia, Porphyromonas gingivalis, and Treponema denticola was performed through real-time PCR. The micro-organism most frequently detected in heart valve samples was the S. mutans (89.3%), followed by P. intermedia (19.1%), P. gingivalis (4.2%), and T. denticola (2.1%). The mean decayed, missing, filled teeth (DMFT) was 26.4 ± 6.9 (mean ± SD), and according to the highest score of periodontal disease observed for each patient, periodontal pockets > 4 mm and dental calculus were detected in 43.4% and 34.7% of patients, respectively. In conclusion, oral bacteria, especially S. mutans, were found in the cardiac valve samples of patients with a high rate of caries and gingivitis/periodontitis. PMID:26632711

  16. Molecular Analysis of Oral Bacteria in Heart Valve of Patients With Cardiovascular Disease by Real-Time Polymerase Chain Reaction.

    PubMed

    Oliveira, Francisco Artur Forte; Forte, Clarissa Pessoa Fernandes; Silva, Paulo Goberlânio de Barros; Lopes, Camile B; Montenegro, Raquel Carvalho; Santos, Ândrea Kely Campos Ribeiro Dos; Sobrinho, Carlos Roberto Martins Rodrigues; Mota, Mário Rogério Lima; Sousa, Fabrício Bitu; Alves, Ana Paula Negreiros Nunes

    2015-11-01

    Structural deficiencies and functional abnormalities of heart valves represent an important cause of cardiovascular morbidity and mortality, and a number of diseases, such as aortic stenosis, have been recently associated with infectious agents. This study aimed to analyze oral bacteria in dental plaque, saliva, and cardiac valves of patients with cardiovascular disease. Samples of supragingival plaque, subgingival plaque, saliva, and cardiac valve tissue were collected from 42 patients with heart valve disease. Molecular analysis of Streptococcus mutans, Prevotella intermedia, Porphyromonas gingivalis, and Treponema denticola was performed through real-time PCR. The micro-organism most frequently detected in heart valve samples was the S. mutans (89.3%), followed by P. intermedia (19.1%), P. gingivalis (4.2%), and T. denticola (2.1%). The mean decayed, missing, filled teeth (DMFT) was 26.4 ± 6.9 (mean ± SD), and according to the highest score of periodontal disease observed for each patient, periodontal pockets > 4 mm and dental calculus were detected in 43.4% and 34.7% of patients, respectively. In conclusion, oral bacteria, especially S. mutans, were found in the cardiac valve samples of patients with a high rate of caries and gingivitis/periodontitis.

  17. Is the time-dependent behaviour of the aortic valve intrinsically quasi-linear?

    NASA Astrophysics Data System (ADS)

    Anssari-Benam, Afshin

    2014-05-01

    The widely popular quasi-linear viscoelasticity (QLV) theory has been employed extensively in the literature for characterising the time-dependent behaviour of many biological tissues, including the aortic valve (AV). However, in contrast to other tissues, application of QLV to AV data has been met with varying success, with studies reporting discrepancies in the values of the associated quantified parameters for data collected from different timescales in experiments. Furthermore, some studies investigating the stress-relaxation phenomenon in valvular tissues have suggested discrete relaxation spectra, as an alternative to the continuous spectrum proposed by the QLV. These indications put forward a more fundamental question: Is the time-dependent behaviour of the aortic valve intrinsically quasi-linear? In other words, can the inherent characteristics of the tissue that govern its biomechanical behaviour facilitate a quasi-linear time-dependent behaviour? This paper attempts to address these questions by presenting a mathematical analysis to derive the expressions for the stress-relaxation G( t) and creep J( t) functions for the AV tissue within the QLV theory. The principal inherent characteristic of the tissue is incorporated into the QLV formulation in the form of the well-established gradual fibre recruitment model, and the corresponding expressions for G( t) and J( t) are derived. The outcomes indicate that the resulting stress-relaxation and creep functions do not appear to voluntarily follow the observed experimental trends reported in previous studies. These results highlight that the time-dependent behaviour of the AV may not be quasi-linear, and more suitable theoretical criteria and models may be required to explain the phenomenon based on tissue's microstructure, and for more accurate estimation of the associated material parameters. In general, these results may further be applicable to other planar soft tissues of the same class, i.e. with the same

  18. Nanosecond spin relaxation times in single layer graphene spin valves with hexagonal boron nitride tunnel barriers

    NASA Astrophysics Data System (ADS)

    Singh, Simranjeet; Katoch, Jyoti; Xu, Jinsong; Tan, Cheng; Zhu, Tiancong; Amamou, Walid; Hone, James; Kawakami, Roland

    2016-09-01

    We present an experimental study of spin transport in single layer graphene using atomic sheets of hexagonal boron nitride (h-BN) as a tunnel barrier for spin injection. While h-BN is expected to be favorable for spin injection, previous experimental studies have been unable to achieve spin relaxation times in the nanosecond regime, suggesting potential problems originating from the contacts. Here, we investigate spin relaxation in graphene spin valves with h-BN barriers and observe room temperature spin lifetimes in excess of a nanosecond, which provides experimental confirmation that h-BN is indeed a good barrier material for spin injection into graphene. By carrying out measurements with different thicknesses of h-BN, we show that few layer h-BN is a better choice than monolayer for achieving high non-local spin signals and longer spin relaxation times in graphene.

  19. Standing valve

    SciTech Connect

    Coleman, S.B.

    1990-08-28

    This patent discusses an apparatus for removing fluids from a wellbore. It comprises a valve housing fixedly secured to a wellbore tubing string, the housing having perforations and a valve seating surface; a valve stem alignment guide secured to the valve housing; a valve stem adapted for movement in the valve stem alignment guide; and a valve seating device attached to the valve stem and capable of contacting the valve seating surface, thereby preventing fluid flow through the valve housing and past the valve seating surface when the seating device and valve seating surface are in contact.

  20. Evaluation of mitral valve prolapse using newly developed real-time three-dimensional echocardiographic system with real-time volume rendering.

    PubMed

    Goktekin, Omer; Matsumura, Makoto; Omoto, Ryozo; Kyo, Shunei; Mochizuki, Tsuyoshi

    2003-02-01

    The development of a real-time three-dimensional (RT3D) image acquisition system and direct digital links between ultrasound equipment and the data processing computer facilitate improved 3D image reconstruction. However, at present time, it is hard to promptly display 3D images and is also ineffective for a practical use. The objective of this study was to assess the feasibility of a new transthoracic RT3D echocardiographic system for evaluation of mitral valve prolapse. Eighteen patients with mitral valve prolapse diagnosed by transthoracic two-dimensional (2D) echocardiography and M-mode were examined through this technique (11 male, mean age 42 +/- 17 years). Since visualization of mitral valve from apical four-chamber view was better than that of the parasternal approach, only apical approach was used for mitral valve evaluation. This system is capable of acquiring volumetric data from mechanical scanning of the phased-array transducer (3.5 MHz) as well as displaying the volume rendered images of the structure without storing the image data and reconstruction of the object. The prolapse of leaflet could be seen in 14/ 18 (77%) of patients with mitral valve prolapse based on conventional echocardiography. The newly developed transthoracic RT 3D ultrasound system without a reconstruction process seemed to be a useful noninvasive tool for diagnosis of mitral valve prolapse and detection of prolapsed leaflet or scallop, which is very important for deciding on a reliable surgical technique.

  1. Fast acting check valve

    NASA Technical Reports Server (NTRS)

    Perkins, Gerald S. (Inventor)

    1979-01-01

    A check valve which closes more rapidly to prevent wearing of the valve seat and of the valve member that seals thereagainst, including a solenoid or other actuator that aids the normal spring to quickly close the valve at approximately the time when downpath fluid flow would stop, the actuator then being deenergized. The control circuit that operates the actuator can include a pair of pressure sensors sensing pressure both upstream and downstream from the valve seat. Where the valve is utilized to control flow to or from a piston pump, energization of the actuator can be controlled by sensing when the pump piston reaches its extreme of travel.

  2. TIME DEPENDENT BIAXIAL MECHANICAL BEHAVIOR OF THE AORTIC HEART VALVE LEAFLET

    PubMed Central

    Stella, John A.; Liao, Jun; Sacks, Michael S.

    2007-01-01

    Despite continued progress in the treatment of aortic valve (AV) disease, current treatments continue to be challenged to consistently restore AV function for extended durations. Improved approaches toward AV repair and replacement rests upon our ability to more fully comprehend and simulate AV function. While the elastic behavior the AV leaflet (AVL) has been previously investigated, time dependent behaviors under physiological biaxial loading states have yet to be quantified. In the current study, we performed strain rate, creep, and stress relaxation experiments using porcine AVL under planar biaxial stretch and loaded to physiological levels (60 N/m equi-biaxial tension), with strain rates ranging from quasi-static to physiologic. The resulting stress-strain responses were found to be independent of strain rate, as was the observed low level of hysteresis (∼17%). Stress relaxation and creep results indicated that while the AVL exhibited significant stress relaxation, it exhibited negligible creep over the three hour test duration. These results are all in accordance with our previous findings for the mitral valve anterior leaflet (MVAL) (Grashow et al., 2006, ABME vol. 34, pp. 315-25; Grashow et al., ABME, Vol. 34, pp. 1509-18, 2006), and support our observations that valvular tissues are functionally anisotropic, quasi-elastic biological materials. These results appear to be unique to valvular tissues, and indicate an ability to withstand loading without time-dependent effects under physiologic loading conditions. Based on a recent study that suggested valvular collagen fibrils are not intrinsically viscoelastic (Liao, et al., JBME, vol. 129, 2007), we speculate that the mechanisms underlying this quasi-elastic behavior may be attributed to supra-fibrillar structure unique to valvular tissue. These mechanisms are an important functional aspect of native valvular tissues, and are likely critical to improve our understanding of valvular disease and help guide

  3. System for detecting operating errors in a variable valve timing engine using pressure sensors

    DOEpatents

    Wiles, Matthew A.; Marriot, Craig D

    2013-07-02

    A method and control module includes a pressure sensor data comparison module that compares measured pressure volume signal segments to ideal pressure volume segments. A valve actuation hardware remedy module performs a hardware remedy in response to comparing the measured pressure volume signal segments to the ideal pressure volume segments when a valve actuation hardware failure is detected.

  4. Safety valve

    DOEpatents

    Bergman, Ulf C.

    1984-01-01

    The safety valve contains a resilient gland to be held between a valve seat and a valve member and is secured to the valve member by a sleeve surrounding the end of the valve member adjacent to the valve seat. The sleeve is movable relative to the valve member through a limited axial distance and a gap exists between said valve member and said sleeve.

  5. Microblower assisted barometric valve

    DOEpatents

    Rossabi, Joseph; Hyde, Warren K.; Riha, Brian D.; Jackson, Dennis G.; Sappington, Frank

    2005-12-06

    A gas exchange apparatus is provided which provides for both passive fluid flow and blower associated fluid flow through a barometric valve. A battery powered blower is provided which allows for operation of the barometric valve during times when the barometric valve would otherwise be closed, and provides for enhanced volume of gas exchange.

  6. Time-resolved DPIV analysis of vortex dynamics in a left ventricular model through bileaflet mechanical and porcine heart valve prostheses.

    PubMed

    Pierrakos, Olga; Vlachos, Pavios P; Telionis, Demetri P

    2004-12-01

    The performance of the heart after a mitral valve replacement operation greatly depends on the flow character downstream of the valve. The design and implanting orientation of valves may considerably affect the flow development. A study of the hemodynamics of two orientations, anatomical and anti-anatomical, of the St. Jude Medical (SJM) bileaflet valve are presented and compared with those of the SJM Biocor porcine valve, which served also to represent the natural valve. We document the velocity field in a flexible, transparent (LV) using time-resolved digital particle image velocimetry (TRDPIV). Vortex formation and vortex interaction are two important physical phenomena that dominate the filling and emptying of the ventricle. For the three configurations, the following effects were examined: mitral valve inlet jet asymmetry, survival of vortical structures upstream of the aortic valve, vortex-induced velocities and redirection of theflow in abidance of the Biot-Savart law, domain segmentation, resonant times of vortical structures, and regions of stagnantflow. The presence of three distinct flow patterns, for the three configurations, was identified by the location of vortical structures and level of coherence corresponding to a significant variation in the turbulence level distribution inside the LV. The adverse effect of these observations could potentially compromise the efficiency of the LV and result in flow patterns that deviate from those in the natural heart. PMID:15796330

  7. Integration of Remote Sensing derived Actual Evapotranspiration with Meteorological Data for Real Time Demand Forecasting in Semi-arid Regions

    NASA Astrophysics Data System (ADS)

    Ullah, M. K.; Hafeez, M. M.; Chemin, Y.; Faux, R.; Sixsmith, J.

    2010-12-01

    Irrigated agriculture is major consumer of fresh water, but a large part of the water devour for irrigation is wasted due to poor management of irrigation systems. Improving water management in irrigated areas require the analysis of real time water demand in order to determine the possibilities in which it may be modified and rationalised. Real time water demand information in irrigated areas is a key for planning about sustainable use of irrigation water. These activities are needed not only to improve water productivity, but also to increase the sustainability of irrigated agriculture by saving irrigation water. Demand forecasting entail the complete understanding of spatial and expected temporal variability of metrological parameters and evapotranspiration (ET). ET is the overriding aspect for irrigation demand forecasting at farm to catchment scale. Many models have been used to measure the ET rate, either empirical or functional. The major disadvantage of this approach is that most methods generate only point values, resulting in estimates that are not representative of large areas. These methods are based on crop factors under ideal conditions and cannot therefore represent actual crop ET. Satellite remote sensing is a powerful mean to estimate ET over various spatial and temporal scales. For improved irrigation system management and operation, a holistic approach of integrating remote sensing derived ET from SAM-ET (spatial algorithm for mapping ET) algorithm, for Australian agro-ecosystem, with forecasted meteorological data and field application loss functions for major crops were used to forecast actual water demand in Coleambally Irrigation Area (CIA), New South Wales, Australia. It covers approximately 79,000 ha of intensive irrigation and comprise of number of secondary and tertiary canals. In order to capture the spatial variability, CIA has been divided into 22 nodes based on direction of flow and connectivity. All hydrological data of inflow (i

  8. Mesofluidic two stage digital valve

    DOEpatents

    Jansen, John F; Love, Lonnie J; Lind, Randall F; Richardson, Bradley S

    2013-12-31

    A mesofluidic scale digital valve system includes a first mesofluidic scale valve having a valve body including a bore, wherein the valve body is configured to cooperate with a solenoid disposed substantially adjacent to the valve body to translate a poppet carried within the bore. The mesofluidic scale digital valve system also includes a second mesofluidic scale valve disposed substantially perpendicular to the first mesofluidic scale valve. The mesofluidic scale digital valve system further includes a control element in communication with the solenoid, wherein the control element is configured to maintain the solenoid in an energized state for a fixed period of time to provide a desired flow rate through an orifice of the second mesofluidic valve.

  9. ESTIMATED SIL LEVELS AND RISK COMPARISONS FOR RELIEF VALVES AS A FUNCTION OF TIME-IN-SERVICE

    SciTech Connect

    Harris, S.

    2012-03-26

    Risk-based inspection methods enable estimation of the probability of spring-operated relief valves failing on demand at the United States Department of Energy's Savannah River Site (SRS) in Aiken, South Carolina. The paper illustrates an approach based on application of the Frechet and Weibull distributions to SRS and Center for Chemical Process Safety (CCPS) Process Equipment Reliability Database (PERD) proof test results. The methodology enables the estimation of ANSI/ISA-84.00.01 Safety Integrity Levels (SILs) as well as the potential change in SIL level due to modification of the maintenance schedule. Current SRS practices are reviewed and recommendations are made for extending inspection intervals. The paper compares risk-based inspection with specific SILs as maintenance intervals are adjusted. Groups of valves are identified in which maintenance times can be extended as well as different groups in which an increased safety margin may be needed.

  10. Annular sizing using real-time three-dimensional intracardiac echocardiography-guided trans-catheter aortic valve replacement

    PubMed Central

    Rendon, Alejandro; Hamid, Tahir; Kanaganayagam, Gajen; Karunaratne, Devinda; Mahadevan, Vaikom S

    2016-01-01

    Objective Transcatheter aortic valve replacement (TAVR) has been established as an alternative therapy for patients with severe aortic stenosis who are unfit for the surgical aortic valve replacements. Pre and periprocedural imaging for the TAVR procedure is the key to procedural success. Currently transesophageal echocardiography (TOE), including real-time three-dimensional (RT-3D) imaging TOE, has been used for peri-interventional monitoring and guidance for TAVR. We describe our initial experience with real-time three-dimensional intracardiac echocardiography (RT-3DICE), imaging technology for the use in the TAVR procedure. Methods We used RT-3DICE using an ACUSON SC2000 2.0v (Siemens Medical Solution), and a 10F AcuNav V catheter (Siemens-Acuson, Inc, Mountain View, California, USA) in addition to preoperative multislice CT (MSCT) in total of five patients undergoing TAVR procedure. Results Aortic annulus and sinus of valsalva diameters were measured using RT-3DICE. Aortic valve measurements obtained using RT-3DICE are comparable to those obtained using MSCT with no significant difference in our patients. Conclusions This small study of five patients shows the safe use of RT-3DICE in TAVR Procedure and may help the procedures performed under local anaesthesia without the need for TOE. PMID:27158522

  11. Simplified pulse reactor for real-time long-term in vitro testing of biological heart valves.

    PubMed

    Schleicher, Martina; Sammler, Günther; Schmauder, Michael; Fritze, Olaf; Huber, Agnes J; Schenke-Layland, Katja; Ditze, Günter; Stock, Ulrich A

    2010-05-01

    Long-term function of biological heart valve prostheses (BHV) is limited by structural deterioration leading to failure with associated arterial hypertension. The objective of this work was development of an easy to handle real-time pulse reactor for evaluation of biological and tissue engineered heart valves under different pressures and long-term conditions. The pulse reactor was made of medical grade materials for placement in a 37 degrees C incubator. Heart valves were mounted in a housing disc moving horizontally in culture medium within a cylindrical culture reservoir. The microprocessor-controlled system was driven by pressure resulting in a cardiac-like cycle enabling competent opening and closing of the leaflets with adjustable pulse rates and pressures between 0.25 to 2 Hz and up to 180/80 mmHg, respectively. A custom-made imaging system with an integrated high-speed camera and image processing software allow calculation of effective orifice areas during cardiac cycle. This simple pulse reactor design allows reproducible generation of patient-like pressure conditions and data collection during long-term experiments.

  12. Assessing daily actual evapotranspiration through energy balance: an experiment to evaluate the selfpreservation hypothesis with acquisition time

    NASA Astrophysics Data System (ADS)

    Maltese, A.; Capodici, F.; Ciraolo, G.; La Loggia, G.; Rallo, G.

    2013-10-01

    An operational use of the actual evapotranspiration estimates requires the integration from instantaneous to daily values. This can commonly be achieved under the hypothesis of daytime self-preservation of the evaporative fraction. In this study, it has been evaluated the effect of this assumption on the assessment of daily evapotranspiration from proximity sensing images acquired at hourly intervals over a homogeneous olive groove. Results have been validated by comparison with observations made by a micrometeorological (EC-flux tower) and an eco-physiological (sap flux) sensor. SEBAL model has been applied to thermal and multispectral images acquired during a clear day on August 2009 trough a FLIR A320G thermal camera and a Tetracam MCA II multispectral camera, installed on a tethered helium balloon. Thermal and multispectral images were characterized by very high spatial resolution. This experiment aims to analyze two effects: 1) the consistency of the self-preservation hypothesis for daily estimates of the actual evapotranspiration from hourly assessments at different times of the day; 2) the effects of the spatial resolution on the performances of the energy balance model. To evaluate the effects of the spatial resolution, semi-hourly observations made by a flux tower and sap-flow measures were compared to the evapotranspiration estimates performed using downscaled images at resolutions close to canopy sizes (2, 5 and 10 m). Results show that the best estimates are obtained with a spatial resolution comparable to the average size of the canopy with images taken approximately at 10 UTC.

  13. Plug valve

    DOEpatents

    Wordin, John J.

    1989-01-01

    An improved plug valve wherein a novel shape for the valve plug and valve chamber provide mating surfaces for improved wear characteristics. The novel shape of the valve plug is a frustum of a body of revolution of a curved known as a tractrix, a solid shape otherwise known as a peudosphere.

  14. ELECTROSTRICTION VALVE

    DOEpatents

    Kippenhan, D.O.

    1962-09-25

    An accurately controlled, pulse gas valve is designed capable of delivering output pulses which vary in length from one-tenth millisecond to one second or more, repeated at intervals of a few milliseconds or- more. The pulsed gas valve comprises a column formed of barium titanate discs mounted in stacked relation and electrically connected in parallel, with means for applying voltage across the discs to cause them to expand and effect a mechanical elongation axially of the column. The column is mounted within an enclosure having an inlet port and an outlet port with an internal seat in communication with the outlet port, such that a plug secured to the end of the column will engage the seat of the outlet port to close the outlet port in response to the application of voltage is regulated by a conventional electronic timing circuit connected to the column. (AEC)

  15. An Analysis of the Impact of Valve Closure Time on the Course of Water Hammer

    NASA Astrophysics Data System (ADS)

    Kodura, Apoloniusz

    2016-06-01

    The knowledge of transient flow in pressure pipelines is very important for the designing and describing of pressure networks. The water hammer is the most common example of transient flow in pressure pipelines. During this phenomenon, the transformation of kinetic energy into pressure energy causes significant changes in pressure, which can lead to serious problems in the management of pressure networks. The phenomenon is very complex, and a large number of different factors influence its course. In the case of a water hammer caused by valve closing, the characteristic of gate closure is one of the most important factors. However, this factor is rarely investigated. In this paper, the results of physical experiments with water hammer in steel and PE pipelines are described and analyzed. For each water hammer, characteristics of pressure change and valve closing were recorded. The measurements were compared with the results of calculations perfomed by common methods used by engineers - Michaud's equation and Wood and Jones's method. The comparison revealed very significant differences between the results of calculations and the results of experiments. In addition, it was shown that, the characteristic of butterfly valve closure has a significant influence on water hammer, which should be taken into account in analyzing this phenomenon. Comparison of the results of experiments with the results of calculations? may lead to new, improved calculation methods and to new methods to describe transient flow.

  16. What Is Mitral Valve Prolapse?

    MedlinePlus

    ... may not close tightly. These flaps normally help seal or open the valve. Much of the time, ... and tricuspid valves close. They form a tight seal that prevents blood from flowing back into the ...

  17. Perceval Sutureless Valve – are Sutureless Valves Here?

    PubMed Central

    Chandola, Rahul; Teoh, Kevin; Elhenawy, Abdelsalam; Christakis, George

    2015-01-01

    With the advent of transcatheter aortic valve implantation (TAVI) techniques, a renewed interest has developed in sutureless aortic valve concepts in the last decade. The main feature of sutureless aortic valve implantation is the speed of insertion, thus making implantation easier for the surgeon. As a result, cross clamp times and myocardial ischemia may be reduced. The combined procedures (CABG with AVR in particular) can be done with a short cross clamp time. Perceval valve also provides an increased effective orifice area as compared with a stented bioprosthesis. Sutureless implantation of the Perceval valve is not only associated with shorter cross-clamp and cardiopulmonary bypass times but improved clinical outcomes too. This review covers the sutureless aortic valves and their evolution, with elaborate details on Perceval S valve in particular (which is the most widely used sutureless valve around the globe). PMID:25394851

  18. Check valve

    DOEpatents

    Upton, Hubert Allen; Garcia, Pablo

    1999-08-24

    A check valve for use in a GDCS of a nuclear reactor and having a motor driven disk including a rotatable armature for rotating the check valve disk over its entire range of motion is described. In one embodiment, the check valve includes a valve body having a coolant flow channel extending therethrough. The coolant flow channel includes an inlet end and an outlet end. A valve body seat is located on an inner surface of the valve body. The check valve further includes a disk assembly, sometimes referred to as the motor driven disc, having a counterweight and a disk shaped valve. The disk valve includes a disk base having a seat for seating with the valve body seat. The disk assembly further includes a first hinge pin member which extends at least partially through the disk assembly and is engaged to the disk. The disk valve is rotatable relative to the first hinge pin member. The check valve also includes a motor having a stator frame with a stator bore therein. An armature is rotatably positioned within the stator bore and the armature is coupled to the disk valve to cause the disk valve to rotate about its full range of motion.

  19. Check valve

    DOEpatents

    Upton, H.A.; Garcia, P.

    1999-08-24

    A check valve for use in a GDCS of a nuclear reactor and having a motor driven disk including a rotatable armature for rotating the check valve disk over its entire range of motion is described. In one embodiment, the check valve includes a valve body having a coolant flow channel extending therethrough. The coolant flow channel includes an inlet end and an outlet end. A valve body seat is located on an inner surface of the valve body. The check valve further includes a disk assembly, sometimes referred to as the motor driven disc, having a counterweight and a disk shaped valve. The disk valve includes a disk base having a seat for seating with the valve body seat. The disk assembly further includes a first hinge pin member which extends at least partially through the disk assembly and is engaged to the disk. The disk valve is rotatable relative to the first hinge pin member. The check valve also includes a motor having a stator frame with a stator bore therein. An armature is rotatably positioned within the stator bore and the armature is coupled to the disk valve to cause the disk valve to rotate about its full range of motion. 5 figs.

  20. Improved image guidance technique for minimally invasive mitral valve repair using real-time tracked 3D ultrasound

    NASA Astrophysics Data System (ADS)

    Rankin, Adam; Moore, John; Bainbridge, Daniel; Peters, Terry

    2016-03-01

    In the past ten years, numerous new surgical and interventional techniques have been developed for treating heart valve disease without the need for cardiopulmonary bypass. Heart valve repair is now being performed in a blood-filled environment, reinforcing the need for accurate and intuitive imaging techniques. Previous work has demonstrated how augmenting ultrasound with virtual representations of specific anatomical landmarks can greatly simplify interventional navigation challenges and increase patient safety. These techniques often complicate interventions by requiring additional steps taken to manually define and initialize virtual models. Furthermore, overlaying virtual elements into real-time image data can also obstruct the view of salient image information. To address these limitations, a system was developed that uses real-time volumetric ultrasound alongside magnetically tracked tools presented in an augmented virtuality environment to provide a streamlined navigation guidance platform. In phantom studies simulating a beating-heart navigation task, procedure duration and tool path metrics have achieved comparable performance to previous work in augmented virtuality techniques, and considerable improvement over standard of care ultrasound guidance.

  1. Valve Disease

    MedlinePlus

    ... the need for heart valve surgery. Percutaneous Interventions Balloon valvuloplasty is a procedure that may be used ... procedure works on valves in the same way balloon angioplasty does on the arteries. Like angioplasty, it ...

  2. Real time optical edge enhancement using a Hughes liquid crystal light valve

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin

    1989-01-01

    The discovery of an edge enhancement effect in using a Hughes CdS liquid crystal light valve (LCLV) is reported. An edge-enhanced version of the input writing image can be directly obtained by operating the LCLV at a lower bias frequency and bias voltage. Experimental conditions in which this edge enhancement effect can be optimized are described. Experimental results show that the SNR of the readout image using this technique is superior to that obtained using high-pass filtering. The repeatability of this effect is confirmed by obtaining an edge enhancement result using two different Hughes LCLVs. The applicability of this effect to improve discrimination capability in optical pattern recognition is addressed. The results show that the Hughes LCLV can be used in both continuous tone and edge-enhancing modes by simply adjusting its bias conditions.

  3. Identification of Reference Genes for Quantitative Real Time PCR Assays in Aortic Tissue of Syrian Hamsters with Bicuspid Aortic Valve

    PubMed Central

    Rueda-Martínez, Carmen; Fernández, M. Carmen; Soto-Navarrete, María Teresa; Jiménez-Navarro, Manuel; Durán, Ana Carmen; Fernández, Borja

    2016-01-01

    Bicuspid aortic valve (BAV) is the most frequent congenital cardiac malformation in humans, and appears frequently associated with dilatation of the ascending aorta. This association is likely the result of a common aetiology. Currently, a Syrian hamster strain with a relatively high (∼40%) incidence of BAV constitutes the only spontaneous animal model of BAV disease. The characterization of molecular alterations in the aorta of hamsters with BAV may serve to identify pathophysiological mechanisms and molecular markers of disease in humans. In this report, we evaluate the expression of ten candidate reference genes in aortic tissue of hamsters in order to identify housekeeping genes for normalization using quantitative real time PCR (RT-qPCR) assays. A total of 51 adult (180–240 days old) and 56 old (300–440 days old) animals were used. They belonged to a control strain of hamsters with normal, tricuspid aortic valve (TAV; n = 30), or to the affected strain of hamsters with TAV (n = 45) or BAV (n = 32). The expression stability of the candidate reference genes was determined by RT-qPCR using three statistical algorithms, GeNorm, NormFinder and Bestkeeper. The expression analyses showed that the most stable reference genes for the three algorithms employed were Cdkn1β, G3pdh and Polr2a. We propose the use of Cdkn1β, or both Cdkn1β and G3pdh as reference genes for mRNA expression analyses in Syrian hamster aorta. PMID:27711171

  4. Heart valve surgery

    MedlinePlus

    Valve replacement; Valve repair; Heart valve prosthesis; Mechanical valves, Prosthetic valves ... place. The main types of new valves are: Mechanical -- made of man-made materials, such as metal ( ...

  5. Fast valve

    DOEpatents

    Van Dyke, William J.

    1992-01-01

    A fast valve is disclosed that can close on the order of 7 milliseconds. It is closed by the force of a compressed air spring with the moving parts of the valve designed to be of very light weight and the valve gate being of wedge shaped with O-ring sealed faces to provide sealing contact without metal to metal contact. The combination of the O-ring seal and an air cushion create a soft final movement of the valve closure to prevent the fast air acting valve from having a harsh closing.

  6. Fast valve

    DOEpatents

    Van Dyke, W.J.

    1992-04-07

    A fast valve is disclosed that can close on the order of 7 milliseconds. It is closed by the force of a compressed air spring with the moving parts of the valve designed to be of very light weight and the valve gate being of wedge shaped with O-ring sealed faces to provide sealing contact without metal to metal contact. The combination of the O-ring seal and an air cushion create a soft final movement of the valve closure to prevent the fast air acting valve from having a harsh closing. 4 figs.

  7. Advances in the Treatment of Aortic Valve Disease: is it Time for Companion Diagnostics?

    PubMed Central

    Hinton, Robert B.

    2014-01-01

    Purpose of the review Aortic valve disease (AVD) is a growing public health problem, and the pathogenesis underlying AVD is complex. The lack of durable bioprostheses and pharmacologic therapies remain central needs in care. The purpose of this review is to highlight recent clinical studies that impact the care of children with AVD and to explore ongoing translational research efforts. Recent findings Clinical studies have evaluated the durability of bioprosthetics and surgical strategies, tested statins during early disease, and identified new predictive biomarkers. Large animal models have demonstrated the effectiveness of a novel bioprosthetic scaffold. Mouse models of latent AVD have advanced our ability to elucidate natural history and perform preclinical studies that test new treatments in the context of early disease. Summary Current priorities for AVD patients include identifying new pharmacologic treatments and developing durable bioprostheses. Multidisciplinary efforts are needed that bridge pediatric and adult programs, bring together different types of expertise and leverage network and consortium resources. As our understanding of the underlying complex genetics is better defined, companion diagnostics may transform future clinical trials and ultimately improve the care of patients with AVD by promoting personalized medicine and early intervention. PMID:25089943

  8. The advantages of live/real time three-dimensional transesophageal echocardiography in the assessment of tricuspid valve infective endocarditis.

    PubMed

    Sungur, Aylin; Hsiung, Ming C; Meggo Quiroz, Luis D; Oz, Tuğba Kemaloğlu; Haj Asaad, Ayman; Joshi, Deepak; Dönmez, Cevdet; Güvenç, Tolga S; Nanda, Navin C

    2014-11-01

    Currently, tricuspid valve infective endocarditis (TVIE) is encountered in daily clinical practice more frequently due to the increasing prevalence of illicit intravenous drug use and the implantation of intracardiac devices. In this study, we compared findings from intra-operative live/real time three-dimensional transesophageal echocardiograms (3DTEE) and two-dimensional transesophageal echocardiograms (2DTEE) of 10 patients who underwent surgery for native tricuspid valve (TV) endocarditis. Unlike 2DTEE, 3DTEE allowed en face visualization of the 3 TV leaflets from both, atrial and ventricular aspects, in 9 of the 10 cases. In the remaining patient, in whom 3DTEE could not identify all 3 leaflets en face, the TV was found essentially destroyed at surgery. Using 3DTEE, the number of vegetations was accurately reported when compared with the surgical record. Furthermore, the orientation of each vegetation was the same as noted in the surgical findings. 2DTEE missed the identification of vegetations in 5 patients. The attachment site of vegetations to the TV were also not characterized by 2DTEE in 5 patients. In all 10 cases, 3DTEE characterized the vegetations more accurately with larger dimensions, including those in the azimuthal axis, and volumes. In addition, a perivalvular abscess that lead to surgical intervention was identified by 3DTEE, however, missed by 2DTEE. In conclusion, 3DTEE allows en face visualization of the TV apparatus permitting accurate description of the number and dimensions of vegetations identified by our surgical standard, which ultimately informs patients' prognosis and dictates the timing and planning for surgical intervention. Its use should be in conjunction with 2DTEE when evaluating TVIE.

  9. 76 FR 77479 - Frontseating Service Valves From the People's Republic of China: Extension of Time for the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-13

    ... Countervailing Duty Administrative Reviews, 76 FR 30912 (May 27, 2011). The preliminary results of review are... International Trade Administration Frontseating Service Valves From the People's Republic of China: Extension of... order on frontseating service valves for Zhejiang Sanhua Co., Ltd. and Zhejiang DunAn Hetian Metal...

  10. Fast acting multiple element valve

    DOEpatents

    Yang, Jefferson Y. S.; Wada, James M.

    1991-01-01

    A plurality of slide valve elements having plural axial-spaced annular parts and an internal slide are inserted into a bulkhead in a fluid conduit from a downstream side of the bulkhead, locked in place by a bayonet coupling and set screw, and project through the bulkhead into the upstream conduit. Pneumatic lines connecting the slide valve element actuator to pilot valves are brought out the throat of the valve element to the downstream side. Pilot valves are radially spaced around the exterior of the valve to permit the pneumatic lines to be made identical, thereby to minimize adverse timing tolerances in operation due to pressure variations. Ring manifolds surround the valve adjacent respective pilot valve arrangements to further reduce adverse timing tolerances due to pressure variations, the manifolds being directly connected to the respective pilot valves. Position sensors are provided the valve element slides to signal the precise time at which a slide reaches or passes through a particular point in its stroke to initiate a calibrated timing function.

  11. Improve relief valve reliability

    SciTech Connect

    Nelson, W.E.

    1993-01-01

    This paper reports on careful evaluation of safety relief valves and their service conditions which can improve reliability and permit more time between testing. Some factors that aid in getting long-run results are: Use of valves suitable for service, Attention to design of the relieving system (including use of block valves) and Close attention to repair procedures. Use these procedures for each installation, applying good engineering practices. The Clean Air Act of 1990 and other legislation limiting allowable fugitive emissions in a hydrocarbon processing plant will greatly impact safety relief valve installations. Normal leakage rate from a relief valve will require that it be connected to a closed vent system connected to a recovery or control device. Tying the outlet of an existing valve into a header system can cause accelerated corrosion and operating difficulties. Reliability of many existing safety relief valves may be compromised when they are connected to an outlet header without following good engineering practices. The law has been enacted but all the rules have not been promulgated.

  12. Valve assembly

    SciTech Connect

    Marshala, D.L.

    1986-12-16

    This patent describes a subsurface pump actuated by a reciprocatable sucker rod for producing well liquids from a subsurface reservoir involving a piston adapted to reciprocate within a cylinder immersed in the reservoir, the piston being provided with a traveling valve. The improvement described here comprises valve means connected to the sucker tod for lifting a body of fluid during upstrokes of the sucker rod, the valve means comprising: a barrel assembly having an internal bore and comprising: a lower barrel member; and an upper barrel assembly connected to the lower barrel and having a beveled seating surface with at least one fluid port therethrough.

  13. Accuracy of a Mitral Valve Segmentation Method Using J-Splines for Real-Time 3D Echocardiography Data

    PubMed Central

    Siefert, Andrew W.; Icenogle, David A.; Rabbah, Jean-Pierre; Saikrishnan, Neelakantan; Rossignac, Jarek; Lerakis, Stamatios; Yoganathan, Ajit P.

    2013-01-01

    Patient-specific models of the heart’s mitral valve (MV) exhibit potential for surgical planning. While advances in 3D echocardiography (3DE) have provided adequate resolution to extract MV leaflet geometry, no study has quantitatively assessed the accuracy of their modeled leaflets versus a ground-truth standard for temporal frames beyond systolic closure or for differing valvular dysfunctions. The accuracy of a 3DE-based segmentation methodology based on J-splines was assessed for porcine MVs with known 4D leaflet coordinates within a pulsatile simulator during closure, peak closure, and opening for a control, prolapsed, and billowing MV model. For all time points, the mean distance error between the segmented models and ground-truth data were 0.40±0.32 mm, 0.52±0.51 mm, and 0.74±0.69 mm for the control, flail, and billowing models. For all models and temporal frames, 95% of the distance errors were below 1.64 mm. When applied to a patient data set, segmentation was able to confirm a regurgitant orifice and post-operative improvements in coaptation. This study provides an experimental platform for assessing the accuracy of an MV segmentation methodology at phases beyond systolic closure and for differing MV dysfunctions. Results demonstrate the accuracy of a MV segmentation methodology for the development of future surgical planning tools. PMID:23460042

  14. Nuclear radiation actuated valve

    DOEpatents

    Christiansen, David W.; Schively, Dixon P.

    1985-01-01

    A nuclear radiation actuated valve for a nuclear reactor. The valve has a valve first part (such as a valve rod with piston) and a valve second part (such as a valve tube surrounding the valve rod, with the valve tube having side slots surrounding the piston). Both valve parts have known nuclear radiation swelling characteristics. The valve's first part is positioned to receive nuclear radiation from the nuclear reactor's fuel region. The valve's second part is positioned so that its nuclear radiation induced swelling is different from that of the valve's first part. The valve's second part also is positioned so that the valve's first and second parts create a valve orifice which changes in size due to the different nuclear radiation caused swelling of the valve's first part compared to the valve's second part. The valve may be used in a nuclear reactor's core coolant system.

  15. The Effect of Valve Timing Upon the Performance of a Supercharged Engine at Altitude and an Unsupercharged Engine at Sea Level

    NASA Technical Reports Server (NTRS)

    Schey, Oscar W; Biermann, Arnold E

    1932-01-01

    This investigation was conducted to determine the comparative effects of valve timing on the performance of an unsupercharged engine at sea level and a supercharged engine at altitude. The tests were conducted on the NACA universal test engine. The timing of the four valve events was varied over a wide range; the engine speeds were varied between 1,050 and 1,500 r.p.m.; the compression ratios were varied between 4.35:1 and 7.35:1. The conditions of exhaust pressure and carburetor pressure of a supercharged engine were simulated for altitudes between 0 and 18,000 feet. The results show that optimum valve timing for a supercharged engine at an altitude of 18,000 feet differs slightly from that for an unsupercharged engine at sea level. A small increase in power is obtained by using the optimum timing for 18,000 feet for altitudes above 5,000 feet. The timing of the intake opening and exhaust closing becomes more critical as the compression ratio is increased.

  16. Method of operating a two-stroke-cycle engine with variable valve timing in a four-stroke-cycle mode

    SciTech Connect

    Richeson, W.E.

    1992-07-21

    This patent describes a method of operating an internal combustion engine of the type comprising a piston reciprocable in a cylinder, intake port means for admitting air into the cylinder, an exhaust valve that is opened and closed by valve actuator means independent of crankshaft position, spark ignition means, and fuel injection means. It comprises a first stroke wherein the piston moves from BDC to TDC, a second stroke wherein the piston moves from TDC to BDC, a third stroke wherein the piston moves from BDC to TDC, a fourth stroke wherein the piston moves from TDC to BDC.

  17. 30. Engine controls and valve gear, looking aft on main ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    30. Engine controls and valve gear, looking aft on main (promenade) deck level. Threaded admission valve lift rods (two at immediate left of chronometer) permit adjustment of valve timing in lower and upper admission valves of cylinder (left rod controls lower valve, right rod upper valve). Valve rods are lifted by jaw-like "wipers" during operation. Exhaust valve lift rods and wipers are located to right of chronometer. Crank at extreme right drives valve wiper shaft when engaged to end of eccentric rod, shown under "Crank Indicator" dial. Pair of handles to immediate left of admission valve rods control condenser water valves; handles to right of exhaust valve rods control feedwater flow to boilers from pumps. Gauges indicate boiler pressure (left) and condenser vacuum (right); "Crank Indicator" on wall aids engineer in keeping engine crank off "dead-center" at stop so that engine may be easily restarted. - Ferry TICONDEROGA, Route 7, Shelburne, Chittenden County, VT

  18. Valve-"Health"-Monitoring System

    NASA Technical Reports Server (NTRS)

    Jensen, Scott L.; Drouant, George J.

    2009-01-01

    A system that includes sensors and data acquisition, wireless data-communication, and data-processing subsystems has been developed as a means of both real-time and historical tracking of information indicative of deterioration in the mechanical integrity and performance of a highgeared ball valve or a linearly actuated valve that operates at a temperature between cryogenic and ambient.

  19. Perception Versus Actual Performance in Timely Tissue Plasminogen Activation Administration in the Management of Acute Ischemic Stroke

    PubMed Central

    Lin, Cheryl B; Cox, Margueritte; Olson, DaiWai M; Britz, Gavin W; Constable, Mark; Fonarow, Gregg C; Schwamm, Lee; Peterson, Eric D; Shah, Bimal R

    2015-01-01

    Background Timely thrombolytic therapy can improve stroke outcomes. Nevertheless, the ability of US hospitals to meet guidelines for intravenous tissue plasminogen activator (tPA) remains suboptimal. What is unclear is whether hospitals accurately perceive their rate of tPA “door-to-needle” (DTN) time within 60 minutes and how DTN rates compare across different hospitals. Methods and Results DTN performance was defined by the percentage of treated patients who received tPA within 60 minutes of arrival. Telephone surveys were obtained from staff at 141 Get With The Guidelines hospitals, representing top, middle, and lowDTN performance. Less than one-third (29.1%) of staff accurately identified their DTN performance. Among middle- and low-performing hospitals (n=92), 56 sites (60.9%) overestimated their performance; 42% of middle performers and 85% of low performers overestimated their performance. Sites that overestimated tended to have lower annual volumes of tPA administration (median 8.4 patients [25th to 75th percentile 5.9 to 11.8] versus 10.2 patients [25th to 75th percentile 8.2 to 17.3], P=0.047), smaller percentages of eligible patients receiving tPA (84.7% versus 89.8%, P=0.008), and smaller percentages of DTN ≤60 minutes among treated patients (10.6% versus 16.6%, P=0.002). Conclusions Hospitals often overestimate their ability to deliver timely tPA to treated patients. Our findings indicate the need to routinely provide comparative provider performance rates as a key step to improving the quality of acute stroke care. PMID:26201547

  20. Form and Actuality

    NASA Astrophysics Data System (ADS)

    Bitbol, Michel

    A basic choice underlies physics. It consists of banishing actual situations from theoretical descriptions, in order to reach a universal formal construct. Actualities are then thought of as mere local appearances of a transcendent reality supposedly described by the formal construct. Despite its impressive success, this method has left major loopholes in the foundations of science. In this paper, I document two of these loopholes. One is the problem of time asymmetry in statistical thermodynamics, and the other is the measurement problem of quantum mechanics. Then, adopting a broader philosophical standpoint, I try to turn the whole picture upside down. Here, full priority is given to actuality (construed as a mode of the immanent reality self-reflectively being itself) over formal constructs. The characteristic aporias of this variety of "Copernican revolution" are discussed.

  1. 76 FR 1135 - Frontseating Service Valves From the People's Republic of China: Extension of Time for the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-07

    ... holiday.\\2\\ \\1\\ See Initiation of Antidumping and Countervailing Duty Administrative Reviews, 75 FR 29976... Administrative Determination Deadlines Pursuant to the Tariff Act of 1930, As Amended, 70 FR 24533 (May 10, 2005... International Trade Administration Frontseating Service Valves From the People's Republic of China: Extension...

  2. 76 FR 52935 - Frontseating Service Valves From the People's Republic of China: Extension of Time for the Final...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-08-24

    ... 2008-2010 Antidumping Duty Administrative Review and Partial Rescission of Review, 76 FR 26686 (May 9... Determination Deadlines Pursuant to the Tariff Act of 1930, As Amended, 70 FR 24533 (May 10, 2005). Accordingly... International Trade Administration Frontseating Service Valves From the People's Republic of China: Extension...

  3. Actual timing of neodymium isotopic variations recorded by Fe-Mn crusts in the western North Atlantic

    USGS Publications Warehouse

    Burton, K.W.; Lee, D.-C.; Christensen, J.N.; Halliday, A.N.; Hein, J.R.

    1999-01-01

    Hydrogenetic ferromanganese (Fe-Mn) crusts from the western North Atlantic record variations in the Nd and Pb isotopic composition of Cenozoic deep water preserved during their growth. The timing and cause of the most striking change have been the subject of debate. Some have proposed that the shift took place after 4 Ma in response to the closure of the Panama gateway. Others have argued that the major change in isotope composition occurred as early as 8 Ma. This study presents high-resolution Nd isotope records for crusts previously dated using 10Be/9Be chronology. These data confirm that the shifts in Nd occurred after 4 Ma, consistent with a likely relationship with the closure of the Central American Isthmus and intensification of Northern Hemisphere Glaciation, and in accordance with changes seen in other physical and chemical records. These results illustrate the need for both a robust chronological framework and high-resolution records before a reliable paleoceanographic interpretation can be made of the variations recorded by Fe-Mn crusts.

  4. 49 CFR 236.383 - Valve locks, valves, and valve magnets.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Valve locks, valves, and valve magnets. 236.383... Inspection and Tests § 236.383 Valve locks, valves, and valve magnets. Valve locks on valves of the non-cut-off type shall be tested at least once every three months, and valves and valve magnets shall...

  5. 49 CFR 236.383 - Valve locks, valves, and valve magnets.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Valve locks, valves, and valve magnets. 236.383... Inspection and Tests § 236.383 Valve locks, valves, and valve magnets. Valve locks on valves of the non-cut-off type shall be tested at least once every three months, and valves and valve magnets shall...

  6. 49 CFR 236.383 - Valve locks, valves, and valve magnets.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Valve locks, valves, and valve magnets. 236.383... Inspection and Tests § 236.383 Valve locks, valves, and valve magnets. Valve locks on valves of the non-cut-off type shall be tested at least once every three months, and valves and valve magnets shall...

  7. 49 CFR 236.383 - Valve locks, valves, and valve magnets.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Valve locks, valves, and valve magnets. 236.383... Inspection and Tests § 236.383 Valve locks, valves, and valve magnets. Valve locks on valves of the non-cut-off type shall be tested at least once every three months, and valves and valve magnets shall...

  8. 49 CFR 236.383 - Valve locks, valves, and valve magnets.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Valve locks, valves, and valve magnets. 236.383... Inspection and Tests § 236.383 Valve locks, valves, and valve magnets. Valve locks on valves of the non-cut-off type shall be tested at least once every three months, and valves and valve magnets shall...

  9. Piezoelectric valve

    DOEpatents

    Petrenko, Serhiy Fedorovich

    2013-01-15

    A motorized valve has a housing having an inlet and an outlet to be connected to a pipeline, a saddle connected with the housing, a turn plug having a rod, the turn plug cooperating with the saddle, and a drive for turning the valve body and formed as a piezoelectric drive, the piezoelectric drive including a piezoelectric generator of radially directed standing acoustic waves, which is connected with the housing and is connectable with a pulse current source, and a rotor operatively connected with the piezoelectric generator and kinematically connected with the rod of the turn plug so as to turn the turn plug when the rotor is actuated by the piezoelectric generator.

  10. An Integer Batch Scheduling Model for a Single Machine with Simultaneous Learning and Deterioration Effects to Minimize Total Actual Flow Time

    NASA Astrophysics Data System (ADS)

    Yusriski, R.; Sukoyo; Samadhi, T. M. A. A.; Halim, A. H.

    2016-02-01

    In the manufacturing industry, several identical parts can be processed in batches, and setup time is needed between two consecutive batches. Since the processing times of batches are not always fixed during a scheduling period due to learning and deterioration effects, this research deals with batch scheduling problems with simultaneous learning and deterioration effects. The objective is to minimize total actual flow time, defined as a time interval between the arrival of all parts at the shop and their common due date. The decision variables are the number of batches, integer batch sizes, and the sequence of the resulting batches. This research proposes a heuristic algorithm based on the Lagrange Relaxation. The effectiveness of the proposed algorithm is determined by comparing the resulting solutions of the algorithm to the respective optimal solution obtained from the enumeration method. Numerical experience results show that the average of difference among the solutions is 0.05%.

  11. Valve assembly and fuel metering apparatus

    SciTech Connect

    Chute, R.

    1988-11-29

    This patent describes an improvement in a liquid flow valving assembly comprising valve body means, valve seating surface means carried by the body means, a purality of passages formed through the body means, each of the passages comprising an upstream inlet end generally surrounded by the seating surface means and a downstream outlet end, a valve member, the valve member comprising a valving surface means for at times sealingly engaging the seating surface means, the valve member being movable in a first direction for causing the valving surface means to sealingly engage the seating surface means to thereby terminate flow of liquid through each of the plurality of passages, the valve member being movable in a second direction opposite to the first direction to thereby open each of the passages to the flow of the liquid therethrough, wherein the first and second directions of movement comprise a single axis of movement, stationary stem-like guide means for guiding the valve member along the single axis of movement during the time that the valve member is moving in the first direction as well as during the time that the valve member is moving in the second direction, wherein the passages are each located in the body means as to be radially outwardly of the stem-like guide means and radially outwardly of the single axis of movement, means for causing the movement of the valve member along the stem-like guide means in the first and second directions, wherein the means for causing the movement of the valve member comprises electrically energizable coil means effective to cyclically produce a flux field for the corresponding cyclic movement of the valve member along the stem-like guide means and in the second direction, and wherein the valve member extends into the region of the coil means and the flux field as to be acted upon thereby.

  12. Aerosol penetration through respirator exhalation valves.

    PubMed

    Bellin, P; Hinds, W C

    1990-10-01

    Exhalation valves are a critical component of industrial respirators. They are designed to permit minimal inward leakage of air contaminants during inhalation and provide low resistance during exhalation. Under normal conditions, penetration of aerosol through exhalation valves is minimal. The exhalation valve is, however, a vulnerable component of a respirator and under actual working conditions may become dirty or damaged to the point of causing significant leakage. Aerosol penetration was measured for normal exhalation valves and valves compromised by paint or fine copper wires on the valve seat. Penetration increased with increasing wire diameter. A wire 250 microns in diameter allowed greater than 1% penetration into the mask cavity. Dirt or paint accumulated on the exhalation valve allowed a similar level of penetration. Work rate had little effect on observed penetration. Penetration decreased significantly with increasing aerosol particle size. The amount of material on the valve or valve seat necessary for significant (greater than 0.5%) inward leakage in a half-mask respirator could be readily observed by careful inspection of the exhalation valve and its seat in good lighting conditions.

  13. Excess flow shutoff valve

    DOEpatents

    Kiffer, Micah S.; Tentarelli, Stephen Clyde

    2016-02-09

    Excess flow shutoff valve comprising a valve body, a valve plug, a partition, and an activation component where the valve plug, the partition, and activation component are disposed within the valve body. A suitable flow restriction is provided to create a pressure difference between the upstream end of the valve plug and the downstream end of the valve plug when fluid flows through the valve body. The pressure difference exceeds a target pressure difference needed to activate the activation component when fluid flow through the valve body is higher than a desired rate, and thereby closes the valve.

  14. Plasma valve

    DOEpatents

    Hershcovitch, Ady; Sharma, Sushil; Noonan, John; Rotela, Elbio; Khounsary, Ali

    2003-01-01

    A plasma valve includes a confinement channel and primary anode and cathode disposed therein. An ignition cathode is disposed adjacent the primary cathode. Power supplies are joined to the cathodes and anode for rapidly igniting and maintaining a plasma in the channel for preventing leakage of atmospheric pressure through the channel.

  15. Thermostatic Radiator Valve Evaluation

    SciTech Connect

    Dentz, Jordan; Ansanelli, Eric

    2015-01-01

    A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market.

  16. Variable Valve Actuation

    SciTech Connect

    Jeffrey Gutterman; A. J. Lasley

    2008-08-31

    Many approaches exist to enable advanced mode, low temperature combustion systems for diesel engines - such as premixed charge compression ignition (PCCI), Homogeneous Charge Compression Ignition (HCCI) or other HCCI-like combustion modes. The fuel properties and the quantity, distribution and temperature profile of air, fuel and residual fraction in the cylinder can have a marked effect on the heat release rate and combustion phasing. Figure 1 shows that a systems approach is required for HCCI-like combustion. While the exact requirements remain unclear (and will vary depending on fuel, engine size and application), some form of substantially variable valve actuation is a likely element in such a system. Variable valve actuation, for both intake and exhaust valve events, is a potent tool for controlling the parameters that are critical to HCCI-like combustion and expanding its operational range. Additionally, VVA can be used to optimize the combustion process as well as exhaust temperatures and impact the after treatment system requirements and its associated cost. Delphi Corporation has major manufacturing and product development and applied R&D expertise in the valve train area. Historical R&D experience includes the development of fully variable electro-hydraulic valve train on research engines as well as several generations of mechanical VVA for gasoline systems. This experience has enabled us to evaluate various implementations and determine the strengths and weaknesses of each. While a fully variable electro-hydraulic valve train system might be the 'ideal' solution technically for maximum flexibility in the timing and control of the valve events, its complexity, associated costs, and high power consumption make its implementation on low cost high volume applications unlikely. Conversely, a simple mechanical system might be a low cost solution but not deliver the flexibility required for HCCI operation. After modeling more than 200 variations of the

  17. Force measuring valve assemblies, systems including such valve assemblies and related methods

    DOEpatents

    DeWall, Kevin George; Garcia, Humberto Enrique; McKellar, Michael George

    2012-04-17

    Methods of evaluating a fluid condition may include stroking a valve member and measuring a force acting on the valve member during the stroke. Methods of evaluating a fluid condition may include measuring a force acting on a valve member in the presence of fluid flow over a period of time and evaluating at least one of the frequency of changes in the measured force over the period of time and the magnitude of the changes in the measured force over the period of time to identify the presence of an anomaly in a fluid flow and, optionally, its estimated location. Methods of evaluating a valve condition may include directing a fluid flow through a valve while stroking a valve member, measuring a force acting on the valve member during the stroke, and comparing the measured force to a reference force. Valve assemblies and related systems are also disclosed.

  18. The valve motion characteristics of a reciprocating pump

    NASA Astrophysics Data System (ADS)

    Pei, Junfeng; He, Chao; Lv, Miaorong; Huang, Xianru; Shen, Kejun; Bi, Kunlei

    2016-01-01

    In previous studies on a reciprocating pump, the state, behavior simulation, or experimental analysis of the valve was seldom reported. In the paper, taking a triplex single-acting reciprocating pump as the research object, we established an experimental system for testing valve disc's motion parameters to directly acquire the valve disc motion parameters (acceleration, velocity, and displacement) under actual conditions. Moreover, testing results were compared with the calculation results obtained according to U. Adolph Theory and Approximation Theory. In Approximation Theory, the valve disc motion was not fully considered, thus leading to the large deviation from the actual situation. Compared with the Approximation Theory, U. Adolph Theory is more suitable for the determination of valve disc motion parameters during different strokes and can explain the jumping and hysteresis phenomena of the valve well. A new pump testing method and an experimental system were proposed to provide a new study approach for valve design theory, disc damage mechanism, and pump failure diagnosis.

  19. Ferroelectric Fluid Flow Control Valve

    NASA Technical Reports Server (NTRS)

    Jalink, Antony, Jr. (Inventor); Hellbaum, Richard F. (Inventor); Rohrbach, Wayne W. (Inventor)

    1999-01-01

    An active valve is controlled and driven by external electrical actuation of a ferroelectric actuator to provide for improved passage of the fluid during certain time periods and to provide positive closure of the valve during other time periods. The valve provides improved passage in the direction of flow and positive closure in the direction against the flow. The actuator is a dome shaped internally prestressed ferroelectric actuator having a curvature, said dome shaped actuator having a rim and an apex. and a dome height measured from a plane through said rim said apex that varies with an electric voltage applied between an inside and an outside surface of said dome shaped actuator.

  20. Quadricuspid aortic valves.

    PubMed

    Timperley, Jonathan; Milner, Robert; Marshall, Andrew J; Gilbert, Timothy J

    2002-12-01

    Quadricuspid aortic valves (QAV) are a rare but well recognized cause of significant aortic regurgitation. The first case was found reported in 1862. Since then there have been 110 reported cases of QAV and we report 4 more. Previously, these were diagnosed at the time of surgery or postmortem examination. With advances in echocardiography, including harmonic imaging, and also the advent of transesophageal echocardiography, more cases are being diagnosed prior to surgery. We describe four more cases, three diagnosed preoperatively and one at the time of surgery, and then review the previously reported cases. Of the 114 cases reported, 46 had the aortic valve replaced, most commonly in the 5th and 6th decade of life. Hurwitz and Roberts classified quadricuspid valves according to the size of the leaflets. It has previously been believed that QAVs with four equal sized leaflets were less likely to develop significant aortic regurgitation; however, on review of the available cases, this would not appear to be the case. The preoperative diagnosis of QAVs is important as they can be associated with abnormally placed coronary ostium. Of the 114 cases reported, there are 10 reports of abnormally placed ostia. There has been at least one reported case of death occurring because of obstruction of an abnormally placed right coronary ostium by a prosthetic aortic valve.

  1. VAPOR VALVE

    DOEpatents

    Wouters, L.F.

    1959-08-25

    Electromagnetically operated vapor valves are described for apparatus employed in the separation of isotopes or elements to control the flow of gaseous vapors between a vaporizing charge chamber and an ionizing chamber, The charge chamber and ionizing chamber are positioned in a magnetic field, and the flow of vapors through an orifice connecting the chambers is regulated by regulating the flow of current through a resilient metal strip rigidly mounted at one end and positioned in the magnetic field adjacent to the orifice.

  2. Degenerative mitral valve regurgitation: best practice revolution

    PubMed Central

    Adams, David H.; Rosenhek, Raphael; Falk, Volkmar

    2010-01-01

    Degenerative mitral valve disease often leads to leaflet prolapse due to chordal elongation or rupture, and resulting in mitral valve regurgitation. Guideline referral for surgical intervention centres primarily on symptoms and ventricular dysfunction. The recommended treatment for degenerative mitral valve disease is mitral valve reconstruction, as opposed to valve replacement with a bioprosthetic or mechanical valve, because valve repair is associated with improved event free survival. Recent studies have documented a significant number of patients are not referred in a timely fashion according to established guidelines, and when they are subjected to surgery, an alarming number of patients continue to undergo mitral valve replacement. The debate around appropriate timing of intervention for asymptomatic severe mitral valve regurgitation has put additional emphasis on targeted surgeon referral and the need to ensure a very high rate of mitral valve repair, particularly in the non-elderly population. Current clinical practice remains suboptimal for many patients, and this review explores the need for a ‘best practice revolution’ in the field of degenerative mitral valve regurgitation. PMID:20624767

  3. Mitral valve regurgitation

    MedlinePlus

    Mitral valve regurgitation; Mitral valve insufficiency; Heart mitral regurgitation; Valvular mitral regurgitation ... regurgitation is the most common type of heart valve disorder. Blood that flows between different chambers of ...

  4. Automatic shutoff valve

    NASA Technical Reports Server (NTRS)

    Hawkins, S. F.; Overbey, C. W.

    1980-01-01

    Cellulose-sponge disk absorbs incoming water and expands with enough force to shut valve. When water recedes, valve opens by squeezing sponge dry to its original size. This direct mechanical action is considered more reliable than solenoid valve.

  5. Aortic Valve Disease

    MedlinePlus

    ... Disease Tricuspid Valve Disease Cardiac Rhythm Disturbances Thoracic Aortic Aneurysm Pediatric and Congenital Heart Disease Heart abnormalities that ... Disease Tricuspid Valve Disease Cardiac Rhythm Disturbances Thoracic Aortic Aneurysm Aortic Valve Disease Overview The human heart has ...

  6. Magnetically operated check valve

    NASA Technical Reports Server (NTRS)

    Morris, Brian G. (Inventor); Bozeman, Richard J., Jr. (Inventor)

    1994-01-01

    A magnetically operated check valve is disclosed. The valve is comprised of a valve body and a movable poppet disposed therein. A magnet attracts the poppet to hold the valve shut until the force of fluid flow through the valve overcomes the magnetic attraction and moves the poppet to an unseated, open position. The poppet and magnet are configured and disposed to trap a magnetically attracted particulate and prevent it from flowing to a valve seating region.

  7. Valve for controlling solids flow

    DOEpatents

    Feldman, David K.

    1980-01-01

    A fluidized solids control valve is disclosed that is particularly well adapted for use with a flow of coal or char that includes both large particles and fines. The particles may or may not be fluidized at various times during the operation. The valve includes a tubular body that terminates in a valve seat covered by a normally closed closure plate. The valve body at the seat and the closure plate is provided with aligned longitudinal slots that receive a pivotally supported key plate. The key plate is positionable by an operator in inserted, intermediate and retracted positions respecting the longitudinal slot in the valve body. The key plate normally closes the slot within the closure plate but is shaped and aligned obliquely to the longitudinal slot within the valve body to provide progressively increasing slot openings between the inserted and retracted positions. Transfer members are provided between the operator, key plate and closure plate to move the closure plate into an open position only when the key plate is retracted from the longitudinal slot within the valve body.

  8. Adjustable safety relief valve

    SciTech Connect

    Taylor, W.L.

    1990-06-12

    This patent describes a pressure relief valve having a relief set pressure. It comprises: a valve body having a fluid inlet and outlet, a spherical, metal valve seat associated with the inlet and a valve member comprising at least a portion of a spherical,metal ball attached to a ball holding element, the valve member being biased against the valve seat and thus providing a metal-to-metal seal preventing the passage of fluids past the valve seat when the fluid pressure in the inlet is below the relief pressure setting of the valve.

  9. Real-time optical correlator using computer-generated holographic filter on a liquid crystal light valve

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin; Yu, Jeffrey

    1990-01-01

    Limitations associated with the binary phase-only filter often used in optical correlators are presently circumvented in the writing of complex-valued data on a gray-scale spatial light modulator through the use of a computer-generated hologram (CGH) algorithm. The CGH encodes complex-valued data into nonnegative real CGH data in such a way that it may be encoded in any of the available gray-scale spatial light modulators. A CdS liquid-crystal light valve is used for the complex-valued CGH encoding; computer simulations and experimental results are compared, and the use of such a CGH filter as the synapse hologram in a holographic optical neural net is discussed.

  10. Bipropellant shut-off valve

    NASA Technical Reports Server (NTRS)

    Smith, J. V.

    1971-01-01

    An advanced design of an all metal, fast response, bipropellant, shut-off valve for use on long duration space missions is reported. The valve provides the flow control capability for a 1,000 lb thrust, bipropellant engine using oxygen difluoride and diborane as propellants. The shutoff seal selection is a soft-on-hard metal concept. The soft seal is a spherical shell that seats against a hard conical seat. Beryllium copper and beryllium nickel seals were selected to seal against an electrolyzed Inconel 718 seat. Poppet shaft sealing is achieved by use of hydroformed, Inconel 718 bellows. Two valve assemblies were fabricated and subjected to a series of tests including leak, response time, flow capacity, dry cycles, water cycles, liquid nitrogen cycles, liquid fluorine cycles, and lead-lag operation cycles. These tests demonstrated the ability of the valve to meet design goals.

  11. Microfluidic sieve valves

    DOEpatents

    Quake, Stephen R; Marcus, Joshua S; Hansen, Carl L

    2015-01-13

    Sieve valves for use in microfluidic device are provided. The valves are useful for impeding the flow of particles, such as chromatography beads or cells, in a microfluidic channel while allowing liquid solution to pass through the valve. The valves find particular use in making microfluidic chromatography modules.

  12. Remote actuated valve implant

    DOEpatents

    McKnight, Timothy E.; Johnson, Anthony; Moise, Kenneth J.; Ericson, Milton Nance; Baba, Justin S.; Wilgen, John B.; Evans, Boyd Mccutchen

    2016-05-10

    Valve implant systems positionable within a flow passage, the systems having an inlet, an outlet, and a remotely activatable valve between the inlet and outlet, with the valves being operable to provide intermittent occlusion of the flow path. A remote field is applied to provide thermal or magnetic activation of the valves.

  13. Rotary pneumatic valve

    DOEpatents

    Hardee, Harry C.

    1991-01-01

    A rotary pneumatic valve which is thrust balanced and the pneumatic pressure developed produces only radial loads on the valve cylinder producing negligible resistance and thus minimal torque on the bearings of the valve. The valve is multiplexed such that at least two complete switching cycles occur for each revolution of the cylinder spindle.

  14. Liquid rocket valve components

    NASA Technical Reports Server (NTRS)

    1973-01-01

    A monograph on valves for use with liquid rocket propellant engines is presented. The configurations of the various types of valves are described and illustrated. Design criteria and recommended practices for the various valves are explained. Tables of data are included to show the chief features of valve components in use on operational vehicles.

  15. Remote actuated valve implant

    DOEpatents

    McKnight, Timothy E; Johnson, Anthony; Moise, Jr., Kenneth J; Ericson, Milton Nance; Baba, Justin S; Wilgen, John B; Evans, III, Boyd McCutchen

    2014-02-25

    Valve implant systems positionable within a flow passage, the systems having an inlet, an outlet, and a remotely activatable valve between the inlet and outlet, with the valves being operable to provide intermittent occlusion of the flow path. A remote field is applied to provide thermal or magnetic activation of the valves.

  16. Valve-in-valve-in-valve: Treating endocarditis of a transcatheter heart valve.

    PubMed

    Nguyen, Caroline; Cheong, Adrian P; Himbert, Dominique

    2015-10-01

    Transcatheter heart valve endocarditis is a rare, but life threatening complication. We describe the case of a patient who was successfully treated by transcatheter aortic valve-in-valve-in-valve replacement with a favorable 1-year outcome, despite severe early complications.

  17. Dual stage check valve

    NASA Technical Reports Server (NTRS)

    Whitten, D. E. (Inventor)

    1973-01-01

    A dual stage seat valve head arrangement is described which consists of a primary sealing point located between a fixed orifice seat and a valve poppet, and a secondary sealing point between an orifice poppet and a valve poppet. Upstream of the valve orifice is a flexible, convoluted metal diaphragm attached to the orifice poppet. Downstream of the valve orifice, a finger spring exerts a force against the valve poppet, tending to keep the valve in a closed position. The series arrangement of a double seat and poppet is able to tolerate small particle contamination while minimizing chatter by controlling throttling or metering across the secondary seat, thus preserving the primary sealing surface.

  18. Valve-in-Valve Replacement Using a Sutureless Aortic Valve

    PubMed Central

    Dohmen, Pascal M.; Lehmkuhl, Lukas; Borger, Michael A.; Misfeld, Martin; Mohr, Friedrich W.

    2016-01-01

    Patient: Female, 61 Final Diagnosis: Tissue degeneration Symptoms: Dyspnea Medication: — Clinical Procedure: Redo valve replacement Specialty: Surgery Objective: Rare disease Background: We present a unique case of a 61-year-old female patient with homograft deterioration after redo surgery for prosthetic valve endocarditis with root abscess. Case Report: The first operation was performed for type A dissection with root, arch, and elephant trunk replacement of the thoracic aorta. The present re-redo surgery was performed as valve-in-valve with a sutureless aortic biopros-thesis. The postoperative course was uneventful and the patient was discharged on day 6. Conclusions: The current case report demonstrates that sutureless bioprostheses are an attractive option for surgical valve-in-valve procedures, which can reduce morbidity and mortality. PMID:27694795

  19. Scissor thrust valve actuator

    DOEpatents

    DeWall, Kevin G.; Watkins, John C; Nitzel, Michael E.

    2006-08-29

    Apparatus for actuating a valve includes a support frame and at least one valve driving linkage arm, one end of which is rotatably connected to a valve stem of the valve and the other end of which is rotatably connected to a screw block. A motor connected to the frame is operatively connected to a motor driven shaft which is in threaded screw driving relationship with the screw block. The motor rotates the motor driven shaft which drives translational movement of the screw block which drives rotatable movement of the valve driving linkage arm which drives translational movement of the valve stem. The valve actuator may further include a sensory control element disposed in operative relationship with the valve stem, the sensory control element being adapted to provide control over the position of the valve stem by at least sensing the travel and/or position of the valve stem.

  20. Bioprosthetic heart valves of the future.

    PubMed

    Manji, Rizwan A; Ekser, Burcin; Menkis, Alan H; Cooper, David K C

    2014-01-01

    Glutaraldehyde-fixed bioprosthetic heart valves (GBHVs), derived from pigs or cows, undergo structural valve deterioration (SVD) over time, with calcification and eventual failure. It is generally accepted that SVD is due to chemical processes between glutaraldehyde and free calcium ions in the blood. Valve companies have made significant progress in decreasing SVD from calcification through various valve chemical treatments. However, there are still groups of patients (e.g., children and young adults) that have accelerated SVD of GBHV. Unfortunately, these patients are not ideal patients for valve replacement with mechanical heart valve prostheses as they are at high long-term risk from complications of the mandatory anticoagulation that is required. Thus, there is no "ideal" heart valve replacement for children and young adults. GBHVs represent a form of xenotransplantation, and there is increasing evidence that SVD seen in these valves is at least in part associated with xenograft rejection. We review the evidence that suggests that xenograft rejection of GBHVs is occurring, and that calcification of the valve may be related to this rejection. Furthermore, we review recent research into the transplantation of live porcine organs in non-human primates that may be applicable to GBHVs and consider the potential use of genetically modified pigs as sources of bioprosthetic heart valves.

  1. Self-Organizing Hierarchical Particle Swarm Optimization with Time-Varying Acceleration Coefficients for Economic Dispatch with Valve Point Effects and Multifuel Options

    NASA Astrophysics Data System (ADS)

    Polprasert, Jirawadee; Ongsakul, Weerakorn; Dieu, Vo Ngoc

    2011-06-01

    This paper proposes a self-organizing hierarchical particle swarm optimization (SPSO) with time-varying acceleration coefficients (TVAC) for solving economic dispatch (ED) problem with non-smooth functions including multiple fuel options (MFO) and valve-point loading effects (VPLE). The proposed SPSO with TVAC is the new approach optimizer and good performance for solving ED problems. It can handle the premature convergence of the problem by re-initialization of velocity whenever particles are stagnated in the search space. To properly control both local and global explorations of the swarm during the optimization process, the performance of TVAC is included. The proposed method is tested in different ED problems with non-smooth cost functions and the obtained results are compared to those from many other methods in the literature. The results have revealed that the proposed SPSO with TVAC is effective in finding higher quality solutions for non-smooth ED problems than many other methods.

  2. Valve for fluid control

    SciTech Connect

    Oborny, Michael C.; Paul, Phillip H.; Hencken, Kenneth R.; Frye-Mason, Gregory C.; Manginell, Ronald P.

    2001-01-01

    A valve for controlling fluid flows. This valve, which includes both an actuation device and a valve body provides: the ability to incorporate both the actuation device and valve into a unitary structure that can be placed onto a microchip, the ability to generate higher actuation pressures and thus control higher fluid pressures than conventional microvalves, and a device that draws only microwatts of power. An electrokinetic pump that converts electric potential to hydraulic force is used to operate, or actuate, the valve.

  3. Shunt failure caused by valve collapse.

    PubMed

    Lundar, T; Langmoen, I A; Hovind, K H

    1991-06-01

    Shunt failure due to collapse of the Mini-Holter valve was observed 13 times in 11 out of 179 children with an implanted Mini-Holter ventriculo-peritoneal (VP) or ventriculo-atrial (VA) shunt during a 10 year period. Intussusception of the proximal or distal end of the valve thus caused a shunt failure rate of 6% of the children in this series. Two children experienced this complication twice. All collapsed valves were part of a VP shunt system. Because of this experience use of the mini valve was abandoned and an adult Holter valve was implanted in children over the age of one month. Breakdown of this particular valve has not occurred in 102 children and two hundred adults with the adult Holter shunt system.

  4. Supramolecular spin valves

    NASA Astrophysics Data System (ADS)

    Urdampilleta, M.; Klyatskaya, S.; Cleuziou, J.-P.; Ruben, M.; Wernsdorfer, W.

    2011-07-01

    Magnetic molecules are potential building blocks for the design of spintronic devices. Moreover, molecular materials enable the combination of bottom-up processing techniques, for example with conventional top-down nanofabrication. The development of solid-state spintronic devices based on the giant magnetoresistance, tunnel magnetoresistance and spin-valve effects has revolutionized magnetic memory applications. Recently, a significant improvement of the spin-relaxation time has been observed in organic semiconductor tunnel junctions, single non-magnetic molecules coupled to magnetic electrodes have shown giant magnetoresistance and hybrid devices exploiting the quantum tunnelling properties of single-molecule magnets have been proposed. Herein, we present an original spin-valve device in which a non-magnetic molecular quantum dot, made of a single-walled carbon nanotube contacted with non-magnetic electrodes, is laterally coupled through supramolecular interactions to TbPc2 single-molecule magnets (Pc=phthalocyanine). Their localized magnetic moments lead to a magnetic field dependence of the electrical transport through the single-walled carbon nanotube, resulting in magnetoresistance ratios up to 300% at temperatures less than 1 K. We thus demonstrate the functionality of a supramolecular spin valve without magnetic leads. Our results open up prospects of new spintronic devices with quantum properties.

  5. Supramolecular spin valves.

    PubMed

    Urdampilleta, M; Klyatskaya, S; Cleuziou, J-P; Ruben, M; Wernsdorfer, W

    2011-07-01

    Magnetic molecules are potential building blocks for the design of spintronic devices. Moreover, molecular materials enable the combination of bottom-up processing techniques, for example with conventional top-down nanofabrication. The development of solid-state spintronic devices based on the giant magnetoresistance, tunnel magnetoresistance and spin-valve effects has revolutionized magnetic memory applications. Recently, a significant improvement of the spin-relaxation time has been observed in organic semiconductor tunnel junctions, single non-magnetic molecules coupled to magnetic electrodes have shown giant magnetoresistance and hybrid devices exploiting the quantum tunnelling properties of single-molecule magnets have been proposed. Herein, we present an original spin-valve device in which a non-magnetic molecular quantum dot, made of a single-walled carbon nanotube contacted with non-magnetic electrodes, is laterally coupled through supramolecular interactions to TbPc(2) single-molecule magnets (Pc=phthalocyanine). Their localized magnetic moments lead to a magnetic field dependence of the electrical transport through the single-walled carbon nanotube, resulting in magnetoresistance ratios up to 300% at temperatures less than 1 K. We thus demonstrate the functionality of a supramolecular spin valve without magnetic leads. Our results open up prospects of new spintronic devices with quantum properties. PMID:21685902

  6. Where is the common sense in aortic valve replacement? A review of hemodynamics and sizing of stented tissue valves.

    PubMed

    Doenst, Torsten; Amorim, Paulo A; Al-Alam, Nidal; Lehmann, Sven; Mukherjee, Chirojit; Faerber, Gloria

    2011-11-01

    Heated debates revolve around the hemodynamic performance of stented aortic tissue valves. Because the opening area strongly influences the generation of a pressure gradient over the prosthesis, and the outer diameter determines which valve actually fits into the aortic root, it would seem logical that the valve with the greatest opening area in relation to its outer diameter should allow the best hemodynamic performance. Interestingly, neither of these 2 parameters is reflected by the manufacturing companies' size labels or suggested sizing strategies. In addition, it is known that valves with the same size label from different companies may differ significantly in their actual dimension (outer diameter). Finally, the manufacturer-suggested sizing strategies differ so much that expected differences from valve design may get lost because of differences in sizing. These size and sizing differences and the lack of information on the geometric opening area complicate true hemodynamic comparisons significantly. Furthermore, some fluid dynamic considerations regarding the determination of opening area by echocardiography (the effective orifice area) introduce additional obscuring factors in the attempt to compare hemodynamic performance data of different stented tissue valves. We analyzed the true dimensions of different tissue prostheses and the manufacturer-suggested sizing strategies in relation to published effective orifice areas. We have demonstrated how sizing and implantation strategy have much greater impact on postoperative valve hemodynamics than valve brand or type. In addition, our findings may explain the different opinions regarding valve hemodynamics of different tissue valves. PMID:21703637

  7. A new valve retractor for mitral valve procedures.

    PubMed

    Lucchese, F A; Kalil, R; Prates, P R; Nesralla, I A; Jatene, A D

    1980-02-01

    Optimal exposure greatly facilitates reconstructive mitral valve procedures. We describe an effective method for exposing this valve using a specially designed mitral valve retractor. This technique proved useful in 321 patients who underwent operation on the mitral valve.

  8. Ball valve extractor

    DOEpatents

    Herndon, Charles; Brown, Roger A.

    2002-01-01

    An apparatus and process for removing a ball valve is provided. The ball valve removal tool provides a handle sliding along the length of a shaft. One end of the shaft is secured within an interior cavity of a ball valve while the opposite end of the shaft defines a stop member. By providing a manual sliding force to the handle, the handle impacts the stop member and transmits the force to the ball valve. The direction of the force is along the shaft of the removal tool and disengages the ball valve from the ball valve housing.

  9. Quickly Removable Valve

    NASA Technical Reports Server (NTRS)

    Robbins, John S.

    1988-01-01

    Unit removed with minimal disturbance. Valve inlet and outlet ports adjacent to each other on same side of valve body. Ports inserted into special manifold on fluid line. Valve body attached to manifold by four bolts or, alternatively, by toggle clamps. Electromechanical actuator moves in direction parallel to fluid line to open and close valve. When necessary to clean valve, removed simply by opening bolts or toggle clamps. No need to move or separate ports of fluid line. Valve useful where disturbance of fluid line detrimental or where fast maintenance essential - in oil and chemical industries, automotive vehicles, aircraft, and powerplants.

  10. Pump isolation valve

    DOEpatents

    Kinney, Calvin L.; Wetherill, Todd M.

    1983-08-02

    The pump isolation valve provides a means by which the pump may be selectively isolated from the remainder of the coolant system while being compatible with the internal hydraulic arrangement of the pump during normal operation of the pump. The valve comprises a valve cylinder disposed around the pump and adjacent to the last pump diffuser with a turning vane attached to the lower end of the valve cylinder in a manner so as to hydraulically match with the discharge diffuser. The valve cylinder is connected to a drive means for sliding the valve cylinder relative to the diffuser support cylinder so as to block flow in either direction through the discharge diffuser when the valve is in the closed position and to aid in the flow of the coolant from the discharge diffuser by means of the turning vane when the valve is in the open position.

  11. Mitral Valve Disease

    MedlinePlus

    ... disease occurs when the mitral valve doesn’t work properly. Types of Mitral Valve Disease Types of ... until you are able to go back to work, depending on your job. Everyday activities such as ...

  12. Mitral valve surgery - open

    MedlinePlus

    ... place. There are two types of mitral valves: Mechanical, made of man-made (synthetic) materials, such as ... Mechanical heart valves do not fail often. They last from 12 to 20 years. However, blood clots ...

  13. Aortic valve surgery - open

    MedlinePlus

    ... There are two main types of new valves: Mechanical, made of man-made materials, such as titanium ... Mechanical heart valves do not fail often. However, blood clots can develop on them. If a blood ...

  14. Valve Health Monitor (VHM)

    NASA Technical Reports Server (NTRS)

    Perotti, Jose M.; Delgado, H. (Technical Monitor)

    2002-01-01

    This presentation reports on progress being made on developing a Valve Health Monitor (VHM) Smart Current Signature Sensor. Topics cover include: design needs, target valves, current signatures, VHM design approach and VHM status/conclusions.

  15. Aerodynamic Shutoff Valve

    NASA Technical Reports Server (NTRS)

    Horstman, Raymond H.

    1992-01-01

    Aerodynamic flow achieved by adding fixed fairings to butterfly valve. When valve fully open, fairings align with butterfly and reduce wake. Butterfly free to turn, so valve can be closed, while fairings remain fixed. Design reduces turbulence in flow of air in internal suction system. Valve aids in development of improved porous-surface boundary-layer control system to reduce aerodynamic drag. Applications primarily aerospace. System adapted to boundary-layer control on high-speed land vehicles.

  16. Overflow control valve

    DOEpatents

    Hundal, Rolv; Kessinger, Boyd A.; Parlak, Edward A.

    1984-07-24

    An overflow control valve for use in a liquid sodium coolant pump tank which valve can be extended to create a seal with the pump tank wall or retracted to break the seal thereby accommodating valve removal. An actuating shaft which controls valve disc position also has cams which bear on roller surfaces to force retraction of a sliding cylinder against spring tension to retract the cylinder from sealing contact with the pump tank.

  17. Stemless Ball Valve

    NASA Technical Reports Server (NTRS)

    Burgess, Robert K.; Yakos, David; Walthall, Bryan

    2012-01-01

    This invention utilizes a new method of opening and closing a ball valve. Instead of rotating the ball with a perpendicular stem (as is the case with standard ball valves), the ball is rotated around a fixed axis by two guide pins. This innovation eliminates the leak point that is present in all standard ball valves due to the penetration of an actuation stem through the valve body. The VOST (Venturi Off-Set-Technology) valve has been developed for commercial applications. The standard version of the valve consists of an off-set venturi flow path through the valve. This path is split at the narrowest portion of the venturi, allowing the section upstream from the venturi to be rotated. As this rotation takes place, the venturi becomes restricted as one face rotates with respect to the other, eventually closing off the flow path. A spring-loaded seal made of resilient material is embedded in the upstream face of the valve, making a leak-proof seal between the faces; thus a valve is formed. The spring-loaded lip seal is the only seal that can provide a class six, or bubble-tight, seal against the opposite face of the valve. Tearing action of the seal by high-velocity gas on this early design required relocation of the seal to the downstream face of the valve. In the stemless embodiment of this valve, inner and outer magnetic cartridges are employed to transfer mechanical torque from the outside of the valve to the inside without the use of a stem. This eliminates the leak path caused by the valve stems in standard valves because the stems penetrate through the bodies of these valves.

  18. Heart Valve Diseases

    MedlinePlus

    Your heart has four valves. Normally, these valves open to let blood flow through or out of your heart, and then shut to keep it from flowing ... close tightly. It's one of the most common heart valve conditions. Sometimes it causes regurgitation. Stenosis - when ...

  19. Liquid rocket valve assemblies

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The design and operating characteristics of valve assemblies used in liquid propellant rocket engines are discussed. The subjects considered are as follows: (1) valve selection parameters, (2) major design aspects, (3) design integration of valve subassemblies, and (4) assembly of components and functional tests. Information is provided on engine, stage, and spacecraft checkout procedures.

  20. Dump valve assembly

    DOEpatents

    Owen, T.J.

    1984-01-01

    A dump valve assembly comprising a body having a bore defined by a tapered wall and a truncated spherical valve member adapted to seat along a spherical surface portion thereof against said tapered wall. Means are provided for pivoting said valve member between a closed position engagable with said tapered wall and an open position disengaged therefrom.

  1. Lock For Valve Stem

    NASA Technical Reports Server (NTRS)

    Burley, Richard K.; Guirguis, Kamal S.

    1991-01-01

    Simple, cheap device locks valve stem so its setting cannot be changed by unauthorized people. Device covers valve stem; cover locked in place with standard padlock. Valve lock made of PVC pipe and packing band. Shears, drill or punch, and forming rod only tools needed.

  2. Outcomes and safety of percutaneous aortic valve replacement.

    PubMed

    Zajarias, Alan; Cribier, Alain G

    2009-05-19

    The concept of transcatheter aortic valve replacement was developed with the goal of offering a therapeutic solution to patients with severe symptomatic aortic stenosis who are not considered good candidates for surgical valve replacement. Initial attempts were complicated by vascular access problems and lack of appropriate tools. With time and experience, early problems were solved and the concepts of valve sizing, valve positioning, and patient selection were defined. Technological improvements allowed the use of smaller arterial sheaths to decrease vascular trauma, special catheters to facilitate valve delivery, and treatments on the valve prostheses that would ensure longer durability. After 5 years, the number of transcatheter aortic valve replacements has grown significantly, and will likely continue as this technology becomes increasingly available. Currently, 2 valve models, the Edwards SAPIEN valve (Edwards Lifescience, Irvine, California) and the CoreValve ReValving system (CoreValve Inc., Irvine, California), have been used in over 4,000 cases worldwide for the treatment of symptomatic aortic stenosis. Midterm follow-up shows no evidence of restenosis or prosthetic valve dysfunction. Transfemoral and transapical delivery routes can be selected depending on the quality of vascular access and the type of prosthesis used. Randomized trials that are currently underway will confirm procedural safety and guide the applicability of this technology.

  3. Dynamic characterization of a new accelerated heart valve tester.

    PubMed

    Menzler, F; Haubold, A D; Hwang, N H

    1997-01-01

    This paper presents a new accelerated prosthetic heart valve tester prototype that incorporates a camshaft and poppet valves. A three element Windkessel system is used to mimic the afterload of the human systemic circulation. The device is capable of testing eight valves simultaneously at a rate up to 1,250 cycles/min, while the flow rate, the pressure, and the valve loading can be monitored and adjusted individually. The tester was characterized and calibrated using a set of eight Carpentier-Edwards bioprostheses at a flow rate varying between 3 and 5 L/min. The experiment was carried out with the pressure difference across the closed heart valve maintained between 140 and 190 mmHg. Smooth and complete opening and closing of the valve leaflets was achieved at all cycling rates. This confirms that the velocity profiles approaching the test valves were uniform, an important factor that allows the test valves to open and close synchronously each time.

  4. Propellant isolation shutoff valve program

    NASA Technical Reports Server (NTRS)

    Merritt, F. L.

    1973-01-01

    An analysis and design effort directed to advancing the state-of-the-art of space storable isolation valves for control of flow of the propellants liquid fluorine/hydrazine and Flox/monomethylhydrazine is discussed. Emphasis is on achieving zero liquid leakage and capability of withstanding missions up to 10 years in interplanetary space. Included is a study of all-metal poppet sealing theory, an evaluation of candidate seal configurations, a valve actuator trade-off study and design description of a pneumo-thermally actuated soft metal poppet seal valve. The concepts and analysis leading to the soft seal approach are documented. A theoretical evaluation of seal leakage versus seal loading, related finishes and yield strengths of various materials is provided. Application of a confined soft aluminum seal loaded to 2 to 3 times yield strength is recommended. Use of either an electro-mechanical or pneumatic actuator appears to be feasible for the application.

  5. Prosthetic valves or tissue valves--a vote for mechanical prostheses.

    PubMed

    Horstkotte, D

    1985-01-01

    Thirty years of effort to obtain better substitutes for destroyed human heart valves brought continuous improvement of the various designs and materials used for the prostheses. However, none of the mechanical or tissue valves currently available meet all the requirements of an ideal artificial heart valve. Accurate comparison of results after implantation of mechanical and tissue valves is difficult because there are no randomized studies and most of the published results are gathered from patient groups operated on in different centers and over different time frames. Reliable comparison therefore presumes criteria to assess the success of valve replacement. The late outcome of heart valve replacement can be determined by subjective improvement, improvement of functional capacity and central hemodynamics, normalization of impaired ventricular function and by the frequency of complications related to or induced by the prostheses. Subjective improvement and improvement of functional capacity is obviously dependent on the degree of postoperative normalization of the hemodynamics. The hemodynamic properties of modern mechanical prostheses are superior to those of tissue valves because of the significantly more favourable relation between total prosthetic valve area and effective prosthetic valve orifice area, conditioned by design. These unfavourable hemodynamics are manifest especially when prostheses of smaller sizes are implanted. The main disadvantage of biological valves is their limited durability due to calcification with tissue damage resulting in degeneration and dysfunction. In addition to the risk of re-operation of tissue valves, for some patients hemodynamical deterioration with consecutive decrease of their functional capacity must be expected a considerable time before a second operation is mandatory. When compared with tissue valves, the most important disadvantage of mechanical valves is their thrombogenicity with the need for life

  6. Minimally Invasive Valve Surgery

    PubMed Central

    Pope, Nicolas H.; Ailawadi, Gorav

    2014-01-01

    Cardiac valve surgery is life saving for many patients. The advent of minimally invasive surgical techniques has historically allowed for improvement in both post-operative convalescence and important clinical outcomes. The development of minimally invasive cardiac valve repair and replacement surgery over the past decade is poised to revolutionize the care of cardiac valve patients. Here, we present a review of the history and current trends in minimally invasive aortic and mitral valve repair and replacement, including the development of sutureless bioprosthetic valves. PMID:24797148

  7. Stentless aortic valve replacement: an update

    PubMed Central

    Kobayashi, Junjiro

    2011-01-01

    Although porcine aortic valves or pericardial tissue mounted on a stent have made implantation techniques easier, these valves sacrifice orifice area and increase stress at the attachment of the stent, which causes primary tissue failure. Optimizing hemodynamics to prevent patient–prosthetic mismatch and improve durability, stentless bioprostheses use was revived in the early 1990s. The purpose of this review is to provide a current overview of stentless valves in the aortic position. Retrospective and prospective randomized controlled studies showed similar operative mortality and morbidity in stented and stentless aortic valve replacement (AVR), though stentless AVR required longer cross-clamp and cardiopulmonary bypass time. Several cohort studies showed improved survival after stentless AVR, probably due to better hemodynamic performance and earlier left ventricular (LV) mass regression compared with stented AVR. However, there was a bias of operation age and nonrandomization. A randomized trial supported an improved 8-year survival of patients with the Freestyle or Toronto valves compared with Carpentier–Edwards porcine valves. On the contrary, another randomized study did not show improved clinical outcomes up to 12 years. Freedom from reoperation at 12 years in Toronto stentless porcine valves ranged from 69% to 75%, which is much lower than for Carpentier–Edwards Perimount valves. Cusp tear with consequent aortic regurgitation was the most common cause of structural valve deterioration. Cryolife O’Brien valves also have shorter durability compared with stent valves. Actuarial freedom from reoperation was 44% at 10 years. Early prosthetic valve failure was also reported in patients who underwent root replacement with Shelhigh stentless composite grafts. There was no level I or IIa evidence of more effective orifice area, mean pressure gradient, LV mass regression, surgical risk, durability, and late outcomes in stentless bioprostheses. There is no

  8. Inorganic mercury detection by valve closure response in the freshwater clam Corbicula fluminea: integration of time and water metal concentration changes.

    PubMed

    Tran, Damien; Fournier, Elodie; Durrieu, Gilles; Massabuau, Jean-Charles

    2007-07-01

    The objective of the present study was to monitor water-quality assessment by a biological method. Optimum dissolved inorganic mercury sensitivity in the freshwater bivalve Corbicula fluminea was estimated using a combined approach to determine their potentials and limits in detecting contaminants. Detection by bivalves is based on shell closure, a protective strategy when exposed to a water contaminant. To take the rate of spontaneous closures into account, stress associated with fixation by one valve in common valvometers was integrated, and the spontaneous rhythm was associated with daily activity. The response in conditions where the probability of spontaneous closing is the lowest was thus taken into account. To develop dose-response curves, impedance valvometry, in which lightweight impedance electrodes are applied to study free-ranging animals in low-stress conditions, also was used combined with a new analytical approach. The logistic regression dose-response curves take into account variations in both response time and metal concentration in water to significantly improve the methods aiming at determining the optimal sensitivity threshold response. This approach demonstrates that in C. fluminea, inorganic mercury concentrations under the range of 2.0 to 5.1 microg/L (95% confidence interval) cannot be detected within 5 h of addition. PMID:17665698

  9. Main Oxidizer Valve Design

    NASA Technical Reports Server (NTRS)

    Addona, Brad; Eddleman, David

    2015-01-01

    A developmental Main Oxidizer Valve (MOV) was designed by NASA-MSFC using additive manufacturing processes. The MOV is a pneumatically actuated poppet valve to control the flow of liquid oxygen to an engine's injector. A compression spring is used to return the valve to the closed state when pneumatic pressure is removed from the valve. The valve internal parts are cylindrical in shape, which lends itself to traditional lathe and milling operations. However, the valve body represents a complicated shape and contains the majority of the mass of the valve. Additive manufacturing techniques were used to produce a part that optimized mass and allowed for design features not practical with traditional machining processes.

  10. Importance of mitral valve repair associated with left ventricular reconstruction for patients with ischemic cardiomyopathy: a real-time three-dimensional echocardiographic study

    NASA Technical Reports Server (NTRS)

    Qin, Jian Xin; Shiota, Takahiro; McCarthy, Patrick M.; Asher, Craig R.; Hail, Melanie; Agler, Deborah A.; Popovic, Zoran B.; Greenberg, Neil L.; Smedira, Nicholas G.; Starling, Randall C.; Young, James B.; Thomas, James D.

    2003-01-01

    BACKGROUND: Left ventricular (LV) reconstruction surgery leads to early improvement in LV function in ischemic cardiomyopathy (ICM) patients. This study was designed to evaluate the impact of mitral valve (MV) repair associated with LV reconstruction on LV function 1-year after surgery in ICM patients assessed by real-time 3-dimensional echocardiography (3DE). METHODS AND RESULTS: Sixty ICM patients who underwent the combination surgery (LV reconstruction in 60, MV repair in 30, and revascularization in 52 patients) were studied. Real-time 3DE was performed and LV volumes were obtained at baseline, discharge, 6-month and >or=12-month follow-up. Reduction in end-diastolic volumes (EDV) by 29% and in end-systolic volumes by 38% were demonstrated immediately after surgery and remained at subsequent follow-up (P<0.0001). The LV ejection fraction significantly increased by about 10% at discharge and was maintained >or=12-month (P<0.0001). Although the LV volumes were significantly larger in patients with MV repair before surgery (EDV, 235+/-87 mL versus 193+/-67 mL, P<0.05), they were similar to LV volumes of the patients without MV repair at subsequent follow-ups. However, the EDV increased from 139+/-24 mL to 227+/-79 mL (P<0.01) in 7 patients with recurrent mitral regurgitation (MR). Improvement in New York Heart Association functional class occurred in 81% patients during late follow-up. CONCLUSIONS: Real-time 3DE demonstrates that LV reconstruction provides significant reduction in LV volumes and improvement in LV function which is sustained throughout the 1-year follow-up with 84% cardiac event free survival. If successful, MV repair may prevent LV redilation, while recurrent MR is associated with increased LV volumes.

  11. Valve- And Switch-Monitoring Computer Program

    NASA Technical Reports Server (NTRS)

    Barry, Matthew R.; Lowe, Carlyle M., III

    1991-01-01

    Human operators freed from tedious, repetitive monitoring tasks. Computer program applies techniques of artificial intelligence to monitoring positions of many switches and valves. Uses combination of procedural and declarative programming techniques. NASA's C Language Integrated Production System (CLIPS) provides rule-processing capabilities. Host program, written in C, acquires necessary data and applies valuation algorithm to generate knowledge-based propositions. Written to assist human flight controllers in comparing actual with expected configuration of switches and valves in Space Shuttle; underlying programming concept applicable to other complicated systems as chemical-processing plants, power-plants, and automated assembly lines. Program works with present monitoring equipment and computers.

  12. The Effects of Positioning of Transcatheter Aortic Valve on Fluid Dynamics of the Aortic Root

    PubMed Central

    Su, Jimmy L; Kheradvar, Arash

    2015-01-01

    Transcatheter aortic valve implantation is a novel treatment for severe aortic valve stenosis. Due to the recent use of this technology and the procedural variability, there is very little data that quantifies the hemodynamic consequences of variations in valve placement. Changes in aortic wall stresses and fluid retention in the sinuses of Valsalva can have a significant effect on the clinical response a patient has to the procedure. By comprehensively characterizing complex flow in the sinuses of Valsalva using Digital Particle Image Velocimetry and an advanced heart flow simulator, various positions of a deployed transcatheter valve with respect to a bioprosthetic aortic valve (valve-in-valve) were tested in vitro. Displacements of the transcatheter valve were axial and directed below the simulated native valve annulus. It was determined that for both blood residence time and aortic Reynolds stresses, it is optimal to have the annulus of the transcatheter valve deployed as close to the aortic valve annulus as possible. PMID:25010918

  13. 40 CFR 265.1056 - Standards: Open-ended valves or lines.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... all times except during operations requiring hazardous waste stream flow through the open-ended valve... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Standards: Open-ended valves or lines...-ended valves or lines. (a)(1) Each open-ended valve or line shall be equipped with a cap, blind...

  14. 40 CFR 63.167 - Standards: Open-ended valves or lines.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... times except during operations requiring process fluid flow through the open-ended valve or line, or... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Standards: Open-ended valves or lines...: Open-ended valves or lines. (a)(1) Each open-ended valve or line shall be equipped with a cap,...

  15. 40 CFR 265.1056 - Standards: Open-ended valves or lines.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... all times except during operations requiring hazardous waste stream flow through the open-ended valve... 40 Protection of Environment 26 2011-07-01 2011-07-01 false Standards: Open-ended valves or lines...-ended valves or lines. (a)(1) Each open-ended valve or line shall be equipped with a cap, blind...

  16. 40 CFR 63.167 - Standards: Open-ended valves or lines.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... times except during operations requiring process fluid flow through the open-ended valve or line, or... 40 Protection of Environment 9 2011-07-01 2011-07-01 false Standards: Open-ended valves or lines...: Open-ended valves or lines. (a)(1) Each open-ended valve or line shall be equipped with a cap,...

  17. Engine valve actuation for combustion enhancement

    DOEpatents

    Reitz, Rolf Deneys; Rutland, Christopher J.; Jhavar, Rahul

    2008-03-04

    A combustion chamber valve, such as an intake valve or an exhaust valve, is briefly opened during the compression and/or power strokes of a 4-strokes combustion cycle in an internal combustion engine (in particular, a diesel or CI engine). The brief opening may (1) enhance mixing withing the combustion chamber, allowing more complete oxidation of particulates to decrease engine emissions; and/or may (2) delay ignition until a more desirable time, potentially allowing a means of timing ignition in otherwise difficult-to-control conditions, e.g., in HCCI (Homogeneous Charge Compression Ignition) conditions.

  18. Engine Valve Actuation For Combustion Enhancement

    DOEpatents

    Reitz, Rolf Deneys; Rutland, Christopher J.; Jhavar, Rahul

    2004-05-18

    A combustion chamber valve, such as an intake valve or an exhaust valve, is briefly opened during the compression and/or power strokes of a 4-stroke combustion cycle in an internal combustion engine (in particular, a diesel or CI engine). The brief opening may (1) enhance mixing withing the combustion chamber, allowing more complete oxidation of particulates to decrease engine emissions; and/or may (2) delay ignition until a more desirable time, potentially allowing a means of timing ignition in otherwise difficult-to-control conditions, e.g., in HCCI (Homogeneous Charge Compression Ignition) conditions.

  19. Avoid common relief-valve pitfalls

    SciTech Connect

    Bravo, F.; Contreras, D.; Jester, D.

    1995-08-01

    From the moment that the decision is made to add a relief valve to a process system and, continuing through its installation and operating life, engineers are involved with evaluations, sizing calculations, and documentation. Relief valves are critical to the safe, efficient operation of process systems. However, many times, these devices are not afforded the emphasis that they deserve and this can cause problems. The purpose of this article is to help the engineer to avoid some of the problems that are typically encountered with relief valves. In today`s competitive and quality-driven world, it is important to do it right the first time.

  20. Valve selection in aortic valve endocarditis

    PubMed Central

    Zubrytska, Yana

    2016-01-01

    Aortic prosthetic valve endocarditis (PVE) is a potentially life-threatening disease. Mortality and incidence of infective endocarditis have been reduced in the past 30 years. Medical treatment of aortic PVE may be successful in patients who have a prompt response after antibiotic treatment and who do not have prosthetic dysfunction. In advanced stages, antibiotic therapy alone is insufficient to control the disease, and surgical intervention is necessary. Surgical treatment may be lifesaving, but it is still associated with considerable morbidity and mortality. The aim of surgery is to perform a radical excision of all infected and necrotic tissue, reconstruction of the left ventricle outflow tract, and replacement of the aortic valve. There is no unanimous consensus on which is the optimal prosthesis to implant in this context, and several surgical techniques have been suggested. We aim to analyze the efficacy of the surgical treatment and discuss the issue of valve selection in patients with aortic valve endocarditis. PMID:27785132

  1. CAM operated fuel valve

    SciTech Connect

    Kelly, S.T.; Katchka, J.R.

    1991-09-03

    This patent describes improvement in a fuel control valve construction comprising a housing means having an inlet means adapted to be interconnected to a fuel source and a main outlet means adapted to be interconnected to a main burner means, the housing means having a main valve seat for interconnecting the inlet means with the main outlet means, the housing means having a movable main valve member for opening and closing the main valve seat, the housing means having a movable lever operatively associated with the main valve member and having a manually operable actuator means for controlling the operating positions of the lever, the lever having an intermediate cam follower portion and opposed ends disposed on each side of the cam follower portion with one end of the opposed ends being pivotally mounted to the housing means and with the other end of the opposed ends for operating the main valve member, the housing means having biasing means operatively interconnected to the lever to tend to pivot the lever in one direction that opens the main valve member away from its the main valve seat. The improvement comprises; the housing means has a thermostatically controlled means that is operatively associated with the lever and is adapted to engage and hold the lever in a position wherein the main valve member is in a closed condition against its the main valve seat when the thermostatically controlled means is in one operating condition thereof and the actuator means is in the on condition thereof.

  2. Electrodynamic actuators for rocket engine valves

    NASA Technical Reports Server (NTRS)

    Fiet, O.; Doshi, D.

    1972-01-01

    Actuators, employed in acoustic loudspeakers, operate liquid rocket engine valves by replacing light paper cones with flexible metal diaphragms. Comparative analysis indicates better response time than solenoid actuators, and improved service life and reliability.

  3. Intelligent Flow Control Valve

    NASA Technical Reports Server (NTRS)

    Kelley, Anthony R (Inventor)

    2015-01-01

    The present invention is an intelligent flow control valve which may be inserted into the flow coming out of a pipe and activated to provide a method to stop, measure, and meter flow coming from the open or possibly broken pipe. The intelligent flow control valve may be used to stop the flow while repairs are made. Once repairs have been made, the valve may be removed or used as a control valve to meter the amount of flow from inside the pipe. With the addition of instrumentation, the valve may also be used as a variable area flow meter and flow controller programmed based upon flowing conditions. With robotic additions, the valve may be configured to crawl into a desired pipe location, anchor itself, and activate flow control or metering remotely.

  4. Automatic rotary valve actuator

    SciTech Connect

    Cook, W.E.

    1985-03-28

    This report describes the design, construction, and operation of a microcomputer-controlled valve actuator for operating test valves requiring rotary motion of the valve stem. An AIM 65 microcomputer, using a FORTH language program, controls an air motor and air clutch mounted within an oven to accomplish testing at elevated temperatures. The valve actuator closes the test valve until a preset torque is reached and then opens the valve to its initial starting point. The number of cycles and extremes of rotation are tallied and printed as the test progresses. Provisions are made to accept remote signals to stop the test and to indicate to a remote device when the test has been stopped.

  5. JenaValve.

    PubMed

    Treede, Hendrik; Rastan, Ardawan; Ferrari, Markus; Ensminger, Stephan; Figulla, Hans-Reiner; Mohr, Friedrich-Wilhelm

    2012-09-01

    The JenaValve is a next-generation TAVI device which consists of a well-proven porcine root valve mounted on a low-profile nitinol stent. Feeler guided positioning and clip fixation on the diseased leaflets allow for anatomically correct implantation of the device without rapid pacing. Safety and efficacy of transapical aortic valve implantation using the JenaValve were evaluated in a multicentre prospective study that showed good short and midterm results. The valve was CE-mark released in Europe in September 2011. A post-market registry ensures on-going and prospective data collection in "real-world" patients. The transfemoral JenaValve delivery system will be evaluated in a first-in-man study in the near future. PMID:22995119

  6. Mitral valve-in-valve and valve-in-ring: technical aspects and procedural outcomes.

    PubMed

    Dvir, Danny; Webb, John

    2016-09-18

    There is a growing practice of transcatheter treatment of failed mitral valves after cardiac surgery, including valve-in-valve and valve-in-ring. Although commonly successful, these procedures can be associated with device malposition (including delayed malposition) and elevated post-procedural gradients (especially when performed inside small surgical valves). Valve-in-ring procedures have elevated risks of left ventricular outflow tract obstruction and post-procedural regurgitation. Careful patient selection and meticulous evaluation of patient anatomy and surgical implant characteristics are essential to achieve optimal clinical results with mitral valve-in-valve and valve-in-ring implantation. PMID:27640048

  7. Passively actuated valve

    DOEpatents

    Modro, S. Michael; Ougouag, Abderrafi M.

    2005-09-20

    A passively actuated valve for isolating a high pressure zone from a low pressure zone and discontinuing the isolation when the pressure in the high pressure zone drops below a preset threshold. If the pressure in the high pressure zone drops below the preset threshold, the valve opens and allows flow from the high pressure zone to the low pressure zone. The valve remains open allowing pressure equalization and back-flow should a pressure inversion between the two pressure zone occur.

  8. Development of Long-Lifetime Pulsed Gas Valves for Pulsed Electric Thrusters

    NASA Technical Reports Server (NTRS)

    Burkhardt, Wendel M.; Crapuchettes, John M.; Addona, Brad M.; Polzin, Kurt A.

    2015-01-01

    The design and test results for two types of pulsed gas valves are presented. The valves, a piezo valve and a solenoid actuated valve, must have exceedingly long lifetime to support gas-fed pulsed electric thruster operation for missions of interest. The performance of both valves was tested, with both demonstrating the capability to throttle the gas flow rate while maintaining low leakage levels below 10(exp -3) sccs of He at the beginning of valve lifetime. The piezo valve varies the flow rate by changing the amount that the valve is open, which is a function of applied voltage. This valve demonstrated continuous throttlability from 0-10 mL/s, with opening and closing times of 100 microsecond or less. The solenoid actuated valve flow rate changes as a function of the inlet gas pressure, with demonstrated flow rates in these tests from 2.7-11 mL per second. The valve response time is slower than the piezo valve, opening in 1-2 ms and closing in several ms. The solenoid actuated valve was tested to one million cycles, with the valve performance remaining relatively unchanged throughout the test. Galling of the sliding plunger caused the valve to bind and fail just after one million cycles, but at this point in the test the valve sealing surface leak rate still appeared to be well below the maximum target leak rake of 1×10(exp -3) sccs of He.

  9. Robotic mitral valve surgery.

    PubMed

    Kypson, Alan P; Nifong, L Wiley; Chitwood, W Randolph

    2003-12-01

    A renaissance in cardiac surgery has begun. The early clinical experience with computer-enhanced telemanipulation systems outlines the limitations of this approach despite some procedural success. Technologic advancements, such as the use of nitinol U-clips (Coalescent Surgical Inc., Sunnyvale, CA) instead of sutures requiring manual knot tying, have been shown to decrease operative times significantly. It is expected that with further refinements and development of adjunct technologies, the technique of computer-enhanced endoscopic cardiac surgery will evolve and may prove to be beneficial for many patients. Robotic technology has provided benefits to cardiac surgery. With improved optics and instrumentation, incisions are smaller. The ergometric movements and simulated three-dimensional optics project hand-eye coordination for the surgeon. The placement of the wristlike articulations at the end of the instruments moves the pivoting action to the plane of the mitral annulus. This improves dexterity in tight spaces and allows for ambidextrous suture placement. Sutures can be placed more accurately because of tremor filtration and high-resolution video magnification. Furthermore, the robotic system may have potential as an educational tool. In the near future, surgical vision and training systems might be able to model most surgical procedures through immersive technology. Thus, a "flight simulator" concept emerges where surgeons may be able to practice and perform the operation without a patient. Already, effective curricula for training teams in robotic surgery exist. Nevertheless, certain constraints continue to limit the advancement to a totally endoscopic computer-enhanced mitral valve operation. The current size of the instruments, intrathoracic instrument collisions, and extrathoracic "elbow" conflicts still can limit dexterity. When smaller instruments are developed, these restraints may be resolved. Furthermore, a working port incision is still required for

  10. Aortic or Mitral Valve Replacement With the Biocor and Biocor Supra

    ClinicalTrials.gov

    2016-03-09

    Aortic Valve Insufficiency; Aortic Valve Regurgitation; Aortic Valve Stenosis; Aortic Valve Incompetence; Mitral Valve Insufficiency; Mitral Valve Regurgitation; Mitral Valve Stenosis; Mitral Valve Incompetence

  11. Magnetic Check Valve

    NASA Technical Reports Server (NTRS)

    Morris, Brian G.; Bozeman, Richard J., Jr.

    1994-01-01

    Poppet in proposed check valve restored to closed condition by magnetic attraction instead of spring force. Oscillations suppressed, with consequent reduction of wear. Stationary magnetic disk mounted just upstream of poppet, also containing magnet. Valve body nonmagnetic. Forward pressure or flow would push poppet away from stationary magnetic disk so fluid flows easily around poppet. Stop in valve body prevents poppet from being swept away. When flow stopped or started to reverse, magnetic attraction draws poppet back to disk. Poppet then engages floating O-ring, thereby closing valve and preventing reverse flow. Floating O-ring facilitates sealing at low loads.

  12. Compact gate valve

    DOEpatents

    Bobo, Gerald E.

    1977-01-01

    This invention relates to a double-disc gate valve which is compact, comparatively simple to construct, and capable of maintaining high closing pressures on the valve discs with low frictional forces. The valve casing includes axially aligned ports. Mounted in the casing is a sealed chamber which is pivotable transversely of the axis of the ports. The chamber contains the levers for moving the valve discs axially, and an actuator for the levers. When an external drive means pivots the chamber to a position where the discs are between the ports and axially aligned therewith, the actuator for the levers is energized to move the discs into sealing engagement with the ports.

  13. Triple Starr Valve Replacement

    PubMed Central

    Braimbridge, M. V.; Clement, A. J.; Brown, A. Hedley; Sabar, E.; Mendel, D.

    1969-01-01

    Of nine patients who have had triple valve replacements for organic rheumatic triple valve disease two died in the postoperative period from inadequate myocardial reserve, and a third died four months later from cerebral embolism originating from clot on the left atrial wall. The remainder are well and, except for one, leading normal lives. Though cardiac transplantation has been recommended and used successfully for triple valve disease by Cooley, it is suggested that the long-term outlook today of triple valve replacement is likely to be better than that of transplantation. ImagesFig. 1Fig. 2Fig. 3 PMID:5809243

  14. Solid handling valve

    DOEpatents

    Williams, William R.

    1979-01-01

    The present invention is directed to a solids handling valve for use in combination with lock hoppers utilized for conveying pulverized coal to a coal gasifier. The valve comprises a fluid-actuated flow control piston disposed within a housing and provided with a tapered primary seal having a recessed seat on the housing and a radially expandable fluid-actuated secondary seal. The valve seals are highly resistive to corrosion, erosion and abrasion by the solids, liquids, and gases associated with the gasification process so as to minimize valve failure.

  15. Biological heart valves.

    PubMed

    Ciubotaru, Anatol; Cebotari, Serghei; Tudorache, Igor; Beckmann, Erik; Hilfiker, Andres; Haverich, Axel

    2013-10-01

    Cardiac valvular pathologies are often caused by rheumatic fever in young adults, atherosclerosis in elderly patients, or by congenital malformation of the heart in children, in effect affecting almost all population ages. Almost 300,000 heart valve operations are performed worldwide annually. Tissue valve prostheses have certain advantages over mechanical valves such as biocompatibility, more physiological hemodynamics, and no need for life-long systemic anticoagulation. However, the major disadvantage of biological valves is related to their durability. Nevertheless, during the last decade, the number of patients undergoing biological, rather than mechanical, valve replacement has increased from half to more than three-quarters for biological implants. Continuous improvement in valve fabrication includes development of new models and shapes, novel methods of tissue treatment, and preservation and implantation techniques. These efforts are focused not only on the improvement of morbidity and mortality of the patients but also on the improvement of their quality of life. Heart valve tissue engineering aims to provide durable, "autologous" valve prostheses. These valves demonstrate adaptive growth, which may avoid the need of repeated operations in growing patients.

  16. Hemodynamics driven cardiac valve morphogenesis.

    PubMed

    Steed, Emily; Boselli, Francesco; Vermot, Julien

    2016-07-01

    Mechanical forces are instrumental to cardiovascular development and physiology. The heart beats approximately 2.6 billion times in a human lifetime and heart valves ensure that these contractions result in an efficient, unidirectional flow of the blood. Composed of endocardial cells (EdCs) and extracellular matrix (ECM), cardiac valves are among the most mechanically challenged structures of the body both during and after their development. Understanding how hemodynamic forces modulate cardiovascular function and morphogenesis is key to unraveling the relationship between normal and pathological cardiovascular development and physiology. Most valve diseases have their origins in embryogenesis, either as signs of abnormal developmental processes or the aberrant re-expression of fetal gene programs normally quiescent in adulthood. Here we review recent discoveries in the mechanobiology of cardiac valve development and introduce the latest technologies being developed in the zebrafish, including live cell imaging and optical technologies, as well as modeling approaches that are currently transforming this field. This article is part of a Special Issue entitled: Cardiomyocyte Biology: Integration of Developmental and Environmental Cues in the Heart edited by Marcus Schaub and Hughes Abriel.

  17. Tricuspid valve replacement with a melody stented bovine jugular vein conduit.

    PubMed

    Hermsen, Joshua L; Permut, Lester C; McQuinn, Tim C; Jones, Thomas K; Chen, Jonathan M; McMullan, David Michael

    2014-11-01

    Atrioventricular valve replacement options are limited in infants and small children. The Melody stented bovine jugular vein conduit is being used with increasing frequency for percutaneous pulmonary valve replacement. The Melody valve can be serially dilated over time to accommodate the somatic growth of pediatric patients. We report the initial experience of using the Melody valve as a surgical tricuspid valve replacement in an infant. PMID:25441796

  18. A new technique for mounting and testing frame-supported homograft aortic valves

    PubMed Central

    Donnelly, R. J.; Dexter, F.; Deverall, P. B.; Watson, D. A.

    1971-01-01

    The mounting of homograft aortic valves on rigid frames often produces cusp distortion leading to mechanical dysfunction. This dysfunction can be demonstrated by a simple testing apparatus. A technique of valve mounting has been developed which consistently results in a competent valve with exact and correct cusp apposition. It is clear that the effect of different techniques of sterilization and preservation on valve function cannot be adequately assessed unless valves are mechanically correct at the time of insertion. Images PMID:5089798

  19. DISCONTINUED OR LITTLE USED LARGE GATE VALVE AND VALVE ASSEMBLY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    DISCONTINUED OR LITTLE USED LARGE GATE VALVE AND VALVE ASSEMBLY PATTERNS, PATTERN STORAGE BUILDING. - Stockham Pipe & Fittings Company, Pattern Storage, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  20. A piezoelectrically actuated ball valve

    NASA Technical Reports Server (NTRS)

    Erwin, L. R.; Schwartz, H. W.; Teitelbaum, B. R.

    1972-01-01

    Bimorph strip composed of two layers of poled piezoelectric ceramic material closes and opens valve. Strip performs like capacitator, allowing initial inrush of current when valve is energized and then only small leakage current flows as valve remains energized.

  1. Mitral valve surgery - minimally invasive

    MedlinePlus

    ... valve repair - partial upper or lower sternotomy; Robotically-assisted, endoscopic valve repair, Percutaneous mitral valvuloplasty ... of your life. Biological, made of human or animal tissue. These valves last 10 to 15 years ...

  2. Apparatus comprising magnetically actuated valves and uses thereof

    DOEpatents

    Edwards, Thayne L.; Harper, Jason C.

    2016-07-12

    The present invention, in part, relates to an apparatus having a single-use, normally-closed fluidic valve that is initially maintained in the closed position by a valve element bonded to an adhesive coating. The valve is opened using a magnetic force. The valve element includes a magnetic material or metal. In some examples, the valve is opened by bringing a magnet in proximity to the valve element to provide a magnetic force that delaminates the valve element from the adhesive coating. In particular, the apparatus can be useful for on-chip amplification and/or detection of various targets, including biological targets and any amplifiable targets. Such apparatuses and methods are useful for in-field or real-time detection of targets, especially in limited resource settings.

  3. Computational Analysis of Cryogenic Flow Through a Control Valve

    NASA Technical Reports Server (NTRS)

    Danes, Russell; Woods, Jody; Sulyma, Peter

    2003-01-01

    The initial efforts to develop the capability to model valves used in rocket engine component testing at Stennis Space Center are documented. An axisymmetric model of a control valve with LN2 as the working fluid was developed. The goal was to predict the effect of change in the plug/sear region of the valve prior to testing. The valve flow coefficient was predicted for a range of plug positions. Verification of the calculations was carried out to quantify the uncertainty in the numerical answer. The modeled results compared well qualitatively to experimental trends. Additionally, insights into the flow processes in the valve were obtained. Benefits from the verification process included the ability to use coarser grids and insight into ways to reduce computational time by using double precision accuracy and non-integer grid ratios. Future valve modeling activities will include shape optimization of the valve/seat region and dynamic grid modeling.

  4. Thermostatic Radiator Valve Evaluation

    SciTech Connect

    Dentz, J.; Ansanelli, E.

    2015-01-01

    A large stock of multifamily buildings in the Northeast and Midwest are heated by steam distribution systems. Losses from these systems are typically high and a significant number of apartments are overheated much of the time. Thermostatically controlled radiator valves (TRVs) are one potential strategy to combat this problem, but have not been widely accepted by the residential retrofit market. In this project, the ARIES team sought to better understand the current usage of TRVs by key market players in steam and hot water heating and to conduct limited experiments on the effectiveness of new and old TRVs as a means of controlling space temperatures and reducing heating fuel consumption. The project included a survey of industry professionals, a field experiment comparing old and new TRVs, and cost-benefit modeling analysis using BEopt™ (Building Energy Optimization software).

  5. Lightweight high-temperature fuel metering valves

    NASA Astrophysics Data System (ADS)

    Bennett, Joe

    AlliedSignal Fluid systems has provided fuel metering valve hardware to three aircraft engine manufacturers for evaluation. Two of the progams were Integrated High Performance Turbine Engine Technology (IHPTET) related. The third program was an IR&D effort. Bench tests and evaluation of all three valve designs have been completed, and one of the designs has actually been used for engine test. Engine testing of the other two valve designs is planned for the future. These three designs are similar, but each is intended to be usused in different system configurations, and each valve design offers unique features. The design approaches used for the three valve designs incorporate several new and innovative technologies, including high-temperature brushless dc motor actuators, low-pressure loss metering element design, fiber optic rotarty output position sensor, no-moving-parts oscillating jet flow meter, high-temperature RS (rapid solidification) aluminum alloy, high-temperature elastomeric seals, high-pressure shutoff capabilities, and closed loop electronic fuel flow metering.

  6. Non-plugging injection valve

    DOEpatents

    Carey, Jr., Henry S.

    1985-01-01

    A valve for injecting fluid into a conduit carrying a slurry subject to separation to form deposits capable of plugging openings into the conduit. The valve comprises a valve body that is sealed to the conduit about an aperture formed through the wall of the conduit to receive the fluid to be injected and the valve member of the valve includes a punch portion that extends through the injection aperture to the flow passage, when the valve is closed, to provide a clear channel into the conduit, when the valve is opened, through deposits which might have formed on portions of the valve adjacent the conduit.

  7. How Is Heart Valve Disease Treated?

    MedlinePlus

    ... and replacing it with a man-made or biological valve. Biological valves are made from pig, cow, or human ... the valve. Man-made valves last longer than biological valves and usually don’t have to be ...

  8. Multimodality imaging in heart valve disease

    PubMed Central

    Chambers, John B; Myerson, Saul G; Rajani, Ronak; Morgan-Hughes, Gareth J; Dweck, Marc R

    2016-01-01

    In patients with heart valve disease, echocardiography is the mainstay for diagnosis, assessment and serial surveillance. However, other modalities, notably cardiac MRI and CT, are used if echocardiographic imaging is suboptimal but can also give complementary information to improve assessment of the valve lesion and cardiac compensation to aid the timing of surgery and determine risk. This statement discusses the way these imaging techniques are currently integrated to improve care beyond what is possible with echocardiography alone. PMID:26977308

  9. Shutoff and throttling valve

    NASA Technical Reports Server (NTRS)

    Hays, L. G.

    1974-01-01

    Leaktight shutoff, precise flow control, and very low pressure drop are incorporated in all-metal valve designed for operation under extreme temperatures. Valve constructed with refractory metal is intended for control of high-temperature liquid cesium, but has applications related to control of high- and low-temperature liquids and gases.

  10. Simple, Internally Adjustable Valve

    NASA Technical Reports Server (NTRS)

    Burley, Richard K.

    1990-01-01

    Valve containing simple in-line, adjustable, flow-control orifice made from ordinary plumbing fitting and two allen setscrews. Construction of valve requires only simple drilling, tapping, and grinding. Orifice installed in existing fitting, avoiding changes in rest of plumbing.

  11. Valve for abrasive material

    DOEpatents

    Gardner, Harold S.

    1982-01-01

    A ball valve assembly for controlling the flow of abrasive particulates including an enlarged section at the bore inlet and an enlarged section at the bore outlet. A refractory ceramic annular deflector is positioned in each of the enlarged sections, substantially extending the useful life of the valve.

  12. Heimlich valve and pneumothorax

    PubMed Central

    Gogakos, Apostolos; Barbetakis, Nikolaos; Lazaridis, George; Papaiwannou, Antonis; Karavergou, Anastasia; Lampaki, Sofia; Baka, Sofia; Mpoukovinas, Ioannis; Karavasilis, Vasilis; Kioumis, Ioannis; Pitsiou, Georgia; Katsikogiannis, Nikolaos; Tsakiridis, Kosmas; Rapti, Aggeliki; Trakada, Georgia; Zissimopoulos, Athanasios; Tsirgogianni, Katerina; Zarogoulidis, Konstantinos

    2015-01-01

    The Heimlich valve is a small one-way valve used for chest drainage that empties into a flexible collection device and prevents return of gases or fluids into the pleural space. The Heimlich valve is less than 13 cm (5 inches) long and facilitates patient ambulation. Currently there are several systems in the market. It can be used in many patients instead of a traditional water seal drainage system. The Heimlich chest drainage valve was developed so that the process of draining the pleural cavity could be accomplished in a safe, relatively simple, and efficient manner. This valve system has replaced the cumbersome underwater drainage bottle system. Moreover; the Heimlich valve system connects to chest tubing and allows fluid and air to pass in one direction only. This system functions in any position, and it does not ever need to be clamped, a regulated suction can be attached to it if necessary. The valve drains into a plastic bag that can be held at any level, allowing the patient undergoing chest drainage to be ambulatory simply by carrying the bag. In the current mini review we will present the Heimlich valve system and method of insertion. PMID:25861609

  13. Linear motion valve

    NASA Technical Reports Server (NTRS)

    Chandler, J. A. (Inventor)

    1985-01-01

    The linear motion valve is described. The valve spool employs magnetically permeable rings, spaced apart axially, which engage a sealing assembly having magnetically permeable pole pieces in magnetic relationship with a magnet. The gap between the ring and the pole pieces is sealed with a ferrofluid. Depletion of the ferrofluid is minimized.

  14. Space Vehicle Valve System

    NASA Technical Reports Server (NTRS)

    Kelley, Anthony R. (Inventor); Lindner, Jeffrey L. (Inventor)

    2014-01-01

    The present invention is a space vehicle valve system which controls the internal pressure of a space vehicle and the flow rate of purged gases at a given internal pressure and aperture site. A plurality of quasi-unique variable dimension peaked valve structures cover the purge apertures on a space vehicle. Interchangeable sheet guards configured to cover valve apertures on the peaked valve structure contain a pressure-activated surface on the inner surface. Sheet guards move outwardly from the peaked valve structure when in structural contact with a purge gas stream flowing through the apertures on the space vehicle. Changing the properties of the sheet guards changes the response of the sheet guards at a given internal pressure, providing control of the flow rate at a given aperture site.

  15. Multiple-port valve

    DOEpatents

    Doody, Thomas J.

    1978-08-22

    A multiple-port valve assembly is designed to direct flow from a primary conduit into any one of a plurality of secondary conduits as well as to direct a reverse flow. The valve includes two mating hemispherical sockets that rotatably receive a spherical valve plug. The valve plug is attached to the primary conduit and includes diverging passageways from that conduit to a plurality of ports. Each of the ports is alignable wih one or more of a plurality of secondary conduits fitted into one of the hemispherical sockets. The other hemispherical socket includes a slot for the primary conduit such that the conduit's motion along that slot with rotation of the spherical plug about various axes will position the valve-plug ports in respect to the secondary conduits.

  16. ULTRA HIGH VACUUM VALVE

    DOEpatents

    Fry, W.A.

    1962-05-29

    A valve for high vacuum applications such as the CStellarator where chamber pressures as low as 2 x 10/sup -10/ mm Hg are necessary is designed with a line-of-sight path through the valve for visual inspection of the contents of reactants in such chambers. The valve comprises a turnable resilient metal ball having an aperture therethrough, means for selectively turning the ball to rotate the axis of its line-of-sight path, and soft, deformable opposing orifices that are movable relatively toward said ball to seal with opposite ball surfaces upon said movement of said axis of said line-of-sight path. The valve also includes a bellows seal connected between said orifices and internal actuating means that eliminates the requirement for gasketed turnable valve closing stems. (AEC)

  17. Fuel injection valve connection

    SciTech Connect

    Eshleman, E.S.; Field, M.J.; Penwright, J.L.

    1987-09-15

    A fuel injection valve connection is described which consists of a fuel injection valve having a cylindrical inlet fitting. The fitting has a threaded internal surface and a cylindrical external surface. A fuel connector has a projection with a threaded external surface that mates with the threaded internal surface of the fitting. The connector also has a sleeve with a cylindrical internal surface surrounding the fitting and an O-ring sealingly engaging the internal surface of the sleeve and the external surface of the fitting, whereby the valve may be rotated relative to the connector without breaking the sealing engagement between the valve and the connector, and wherein the connector also has a tab engageable with the injector to prevent unthreading of the valve from the connector.

  18. Transcatheter aortic valve implantation.

    PubMed

    Kapadia, Samir R; Tuzcu, E Murat

    2009-12-01

    Aortic stenosis is the most important valvular heart disease affecting the elderly population. Surgical aortic valve replacement is the mainstay of treatment, although a substantial number of patients are considered high risk for surgery. Many of these patients do not undergo surgery and have poor outcomes from medically treated symptomatic, severe aortic stenosis. Transcatheter aortic valve implantation (TAVI) provides a promising treatment option for some of these patients. Several devices are under investigation. The Edwards Sapien valve (Edwards Lifesciences, Irvine, CA) and the CoreValve (Medtronic, Minneapolis, MN) have the largest human experience to date. Initial data suggest that these devices have an acceptable safety profile and provide excellent hemodynamic relief of aortic stenosis. The Edwards Sapien valve is currently under investigation in the United States in the PARTNER (Placement of Aortic Transcatheter Valve) trial in high-risk surgical or inoperable patients; TAVI is available for clinical use in both Canada and Europe. TAVI is not used in low- or intermediate-risk surgical patients; however, future studies may prove its applicability in these subsets. The major complications of TAVI include access site-related problems and device malpositioning/migration. There are several new-generation prosthetic valves and delivery systems designed to be low profile and repositionable. Technical advances and refinement of the implantation methods may make TAVI even safer and ultimately a better treatment option, not only for patients with high surgical risk but also for those with moderate or low risk.

  19. Computational valve plate design

    NASA Astrophysics Data System (ADS)

    Kalbfleisch, Paul

    Axial piston machines are widely used in many industries for their designs compactness, flexibility in power transfer, variable flow rate, and high efficiencies as compared to their manufacturing costs. One important component of all axial piston machines that is a very influential on the performance of the unit is the valve plate. The aim of this research is to develop a design methodology that is general enough to design all types of valve plates and the simple enough not to require advanced technical knowledge from the user. A new style of valve plate designs has been developed that comprehensively considers all previous design techniques and does not require significant changes to the manufacturing processes of valve plates. The design methodology utilizes a previously developed accurate computer model of the physical phenomenon. This allows the precise optimization of the valve plate design through the use of simulations rather than expensive trial and error processes. The design of the valve plate is clarified into the form of an optimization problem. This formulation into an optimization problem has motivated the selection of an optimization algorithm that satisfies the requirements of the design. The proposed design methodology was successfully tested in a case study in the shown to be very successful in improving required performance of the valve plate design.

  20. Modification and performance evaluation of a mono-valve engine

    NASA Astrophysics Data System (ADS)

    Behrens, Justin W.

    A four-stroke engine utilizing one tappet valve for both the intake and exhaust gas exchange processes has been built and evaluated. The engine operates under its own power, but has a reduced power capacity than the conventional 2-valve engine. The reduction in power is traced to higher than expected amounts of exhaust gases flowing back into the intake system. Design changes to the cylinder head will fix the back flow problems, but the future capacity of mono-valve engine technology cannot be estimated. The back flow of exhaust gases increases the exhaust gas recirculation (EGR) rate and deteriorates combustion. Intake pressure data shows the mono-valve engine requires an advanced intake valve closing (IVC) time to prevent back flow of charge air. A single actuation camshaft with advanced IVC was tested in the mono-valve engine, and was found to improve exhaust scavenging at TDC and nearly eliminated all charge air back flow at IVC. The optimum IVC timing is shown to be approximately 30 crank angle degrees after BDC. The mono-valve cylinder head utilizes a rotary valve positioned above the tappet valve. The open spaces inside the rotary valveand between the rotary valve and tappet valve represent a common volume that needs to be reduced in order to reduce the base EGR rate. Multiple rotary valve configurations were tested, and the size of the common volume was found to have no effect on back flow but a direct effect on the EGR rate and engine performance. The position of the rotary valve with respect to crank angle has a direct effect on the scavenging process. Optimum scavenging occurs when the intake port is opened just after TDC.

  1. Valve body for oilfield applications

    SciTech Connect

    Bailey, T.F.; Campbell, J.E.

    1992-01-21

    This patent describes a valve to pump fluids, save valve sealingly cooperating with a valve set having a throughbore. It comprises a valve head having an axial cavity with an interior annular side wall; a valve body attached to the valve head, the valve body including an axial neck portion received within the cavity of the valve head and having an outer annular surface corresponding to the interior annular side wall of the cavity; and means to lockingly attach the valve body to the valve head, the valve head being made of a metal material and the valve body being made of an elastomer material, the locking means including at least one annular tongue formed on the outer annular surface of the neck portion of the valve body, the at least one tongue having a frusto-conical upper surface, a cylindrical intermediate surface and a curved lower surface the at least one annular tongue lockingly engaging at least one corresponding annular groove formed in the interior annular side wall of the internal cavity of the valve head thereby preventing inadvertent withdrawal of the neck portion from the cavity and separation of the valve body from the valve head.

  2. Face-Sealing Butterfly Valve

    NASA Technical Reports Server (NTRS)

    Tervo, John N.

    1992-01-01

    Valve plate made to translate as well as rotate. Valve opened and closed by turning shaft and lever. Interactions among lever, spring, valve plate, and face seal cause plate to undergo combination of translation and rotation so valve plate clears seal during parts of opening and closing motions.

  3. Sliding-gate valve

    DOEpatents

    Usnick, George B.; Ward, Gene T.; Blair, Henry O.; Roberts, James W.; Warner, Terry N.

    1979-01-01

    This invention is a novel valve of the slidable-gate type. The valve is designed especially for long-term use with highly abrasive slurries. The sealing surfaces of the gate are shielded by the valve seats when the valve is fully open or closed, and the gate-to-seat clearance is swept with an inflowing purge gas while the gate is in transit. A preferred form of the valve includes an annular valve body containing an annular seat assembly defining a flow channel. The seat assembly comprises a first seat ring which is slidably and sealably mounted in the body, and a second seat ring which is tightly fitted in the body. These rings cooperatively define an annular gap which, together with passages in the valve body, forms a guideway extending normal to the channel. A plate-type gate is mounted for reciprocation in the guideway between positions where a portion of the plate closes the channel and where a circular aperture in the gate is in register with the channel. The valve casing includes opposed chambers which extend outwardly from the body along the axis of the guideway to accommodate the end portions of the gate. The chambers are sealed from atmosphere; when the gate is in transit, purge gas is admitted to the chambers and flows inwardly through the gate-to-seat-ring, clearance, minimizing buildup of process solids therein. A shaft reciprocated by an external actuator extends into one of the sealed chambers through a shaft seal and is coupled to an end of the gate. Means are provided for adjusting the clearance between the first seat ring and the gate while the valve is in service.

  4. [MINIMALLY INVASIVE AORTIC VALVE REPLACEMENT].

    PubMed

    Tabata, Minoru

    2016-03-01

    Minimally invasive aortic valve replacement (MIAVR) is defined as aortic valve replacement avoiding full sternotomy. Common approaches include a partial sternotomy right thoracotomy, and a parasternal approach. MIAVR has been shown to have advantages over conventional AVR such as shorter length of stay and smaller amount of blood transfusion and better cosmesis. However, it is also known to have disadvantages such as longer cardiopulmonary bypass and aortic cross-clamp times and potential complications related to peripheral cannulation. Appropriate patient selection is very important. Since the procedure is more complex than conventional AVR, more intensive teamwork in the operating room is essential. Additionally, a team approach during postoperative management is critical to maximize the benefits of MIAVR.

  5. Long life valve design concepts

    NASA Technical Reports Server (NTRS)

    Jones, J. R.; Hall, A. H., Jr.

    1975-01-01

    Valve concept evaluation, final candidate selection, design, manufacture, and demonstration testing of a pneumatically actuated 10-inch hybrid poppet butterfly shutoff valve are presented. Conclusions and recommendations regarding those valve characteristics and features which would serve to guide in the formulation of future valve procurements are discussed. The pertinent design goals were temperature range of plus 200 to minus 423 F, valve inlet pressure 35 psia, actuation pressure 750 psia, main seal leakage 3 x 0.00001 sccs at 35 psia valve inlet pressure, and a storage and operating life of 10 years. The valve was designed to be compatible with RP-1, propane, LH2, LO2, He, and N2.

  6. Percutaneous Pulmonary Valve Placement

    PubMed Central

    Prieto, Lourdes R.

    2015-01-01

    Patients with congenital heart disease and pulmonary valve disease need multiple procedures over their lifetimes to replace their pulmonary valves. Chronic pulmonary stenosis, regurgitation, or both have untoward effects on ventricular function and on the clinical status of these patients. To date, all right ventricle–pulmonary artery conduits have had relatively short lifespans. Percutaneous pulmonary valve implantation, although relatively new, will probably reduce the number of operative procedures that these patients will have to undergo over a lifetime. Refinement and further development of this procedure holds promise for the extension of this technology to other patient populations. PMID:26175629

  7. Performance of needle valves.

    PubMed

    Hutton, P; Boaden, R W

    1986-08-01

    The pressure-flow characteristics of needle valves used on anaesthetic equipment were investigated. It was found that, under normal conditions of use, the valves behaved in a manner similar to convergent nozzles with sonic velocity at the throat. This means that, once the valve has been set, the mass flow rate of gas is effectively independent of the downstream changes in resistance and compliance encountered in normal anaesthetic practice. The error in a preset flow induced by the permissible variations in the upstream pipeline pressure was measured.

  8. Quartz ball valve

    NASA Technical Reports Server (NTRS)

    Goetz, C.; Ingle, W. M. (Inventor)

    1980-01-01

    A ball valve particularly suited for use in the handling of highly corrosive fluids is described. It is characterized by a valve housing formed of communicating segments of quartz tubing, a pair of communicating sockets disposed in coaxial alignment with selected segments of tubing for establishing a pair of inlet ports communicating with a common outlet port, a ball formed of quartz material supported for displacement between the sockets and configured to be received alternately thereby, and a valve actuator including a rod attached to the ball for selectively displacing the ball relative to each of the sockets for controlling fluid flow through the inlet ports.

  9. On the actual variety of plate dynamical mechanisms and how mantle evolution affected them through time, from core formation to the Indian collision

    NASA Astrophysics Data System (ADS)

    Osmaston, Miles

    2010-05-01

    If horizontal plate motions were driven by thermal convection of the mantle, they would display the action of slow-to-change body forces. Yet rapid changes of spreading rate and direction, and ridge jumps, are well-documented for the past 130Ma. Also convection cannot readily cause rotations of a plate (e.g. Africa) about a pole within the plate or near it. And plate motions, especially that of India, scarcely fit a convective pattern. To address these problems we look first at mantle motivation at both ends of earth history, beginning with core formation. I then introduce 3 important properties of mantle materials, whose neglect by mantle modellers has surely impaired the value of their work, but whose recognition illuminates the present plate dynamical situation and provides the Earth with a heat engine that is not thermal convection. Finally I sketch the intervening changes in behaviour over time, the sharpest of which brought about the rise of atmospheric oxygen at ~2.25Ga. Core formation. As the very high specific angular momentum of mean planetary material (>105-fold relative to solar) can only be achieved if the planets were wholly accreted in presence of the nebula [1], the iron percolation model is ruled out, because it takes too long. This validates the A.E.Ringwood model (1960-1978) involving nebular H reaction with erupting FeO. The iron then loads the downgoing limb of what is then not a truly thermal convection system. Huge volumes of reaction water were produced, giving the early Earth a wet mantle, a (diminishing) feature that we'll see has constrained mantle behaviour ever since. Plate dynamics since 150Ma. Multiple plate dynamical evidence [2], which will be rapidly re-presented here, shows that currently (a) the Earth has a 2-layer mantle system with a boundary at ~660km and (b) that most cratons have tectospheric keels that reach right to that boundary, or nearly so. The argument is the simple and persuasive one (even to seismologists) of mantle

  10. How People Actually Use Thermostats

    SciTech Connect

    Meier, Alan; Aragon, Cecilia; Hurwitz, Becky; Mujumdar, Dhawal; Peffer, Therese; Perry, Daniel; Pritoni, Marco

    2010-08-15

    Residential thermostats have been a key element in controlling heating and cooling systems for over sixty years. However, today's modern programmable thermostats (PTs) are complicated and difficult for users to understand, leading to errors in operation and wasted energy. Four separate tests of usability were conducted in preparation for a larger study. These tests included personal interviews, an on-line survey, photographing actual thermostat settings, and measurements of ability to accomplish four tasks related to effective use of a PT. The interviews revealed that many occupants used the PT as an on-off switch and most demonstrated little knowledge of how to operate it. The on-line survey found that 89% of the respondents rarely or never used the PT to set a weekday or weekend program. The photographic survey (in low income homes) found that only 30% of the PTs were actually programmed. In the usability test, we found that we could quantify the difference in usability of two PTs as measured in time to accomplish tasks. Users accomplished the tasks in consistently shorter times with the touchscreen unit than with buttons. None of these studies are representative of the entire population of users but, together, they illustrate the importance of improving user interfaces in PTs.

  11. Ceramic valve development for heavy-duty low heat rejection diesel engines

    NASA Technical Reports Server (NTRS)

    Weber, K. E.; Micu, C. J.

    1989-01-01

    Monolithic ceramic valves can be successfully operated in a heavy-duty diesel engine, even under extreme low heat rejection operating conditions. This paper describes the development of a silicon nitride valve from the initial design stage to actual engine testing. Supplier involvement, finite element analysis, and preliminary proof of concept demonstration testing played a significant role in this project's success.

  12. Fibrinolytic therapy for mechanical pulmonary valve thrombosis.

    PubMed

    Khajali, Zahra; Mohammadzadeh, Shabnam; Maleki, Majid; Peighambari, Mohammad Mehdi; Sadeghpoor, Anita; Ghavidel, Alireza; Elahi, Behrad; Mirzaaghayan, Mohammadreza

    2015-01-01

    Treatment of prosthetic heart valve thrombosis using intravenous thrombolytics, although an acceptable alternative to surgery, is not complication free, and the literature has a dearth of data on the subject. This study analyzed the results of fibrinolytic treatment (FT) among a single-center group of patients with mechanical pulmonary valve thrombosis. Between 2000 and 2013, 23 consecutive patients with 25 episodes of pulmonary valve thrombosis received FT. The diagnosis of mechanical pulmonary valve thrombosis was established by fluoroscopy and echocardiography. Streptokinase (SK) was used in 24 cases and alteplase in 1 case. The FT was continued a second day for 14 patients (58.3%), a third day for 1 patient, and a fourth day for 1 patient. Echocardiography and fluoroscopy were performed every day until improvement of malfunction was achieved. Of the 23 patients, 19 had complete resolution of hemodynamic abnormalities after FT, 1 had partial resolution, and 2 showed no change. No patient had major complications. Five minor complications were detected, namely, fever, nausea, thrombophlebitis, epistaxi, and pain. Seven patients (30%) experienced recurrence of thrombosis, whereas four patients had surgery (biological pulmonary valve replacement) without re-thrombolytic therapy, one patient was treated with Alteplase, one patient received SK, and one patient received intense anticoagulation using heparin and warfarin. Overall, FT had a success rate of 84%. The results indicate that regardless of the time to pulmonary valve replacement and echocardiographic and fluoroscopic findings, FT was effective in most cases of mechanical pulmonary valve thrombosis. The efficacy increased with second-day thrombolytic therapy. Major complications were not common after lytic therapy for mechanical pulmonary valve thrombosis.

  13. Preliminary characterization of active MEMS valves.

    SciTech Connect

    Barnard, Casey Anderson

    2010-08-01

    Partial characterization of a series of electrostatically actuated active microfluidic valves is to be performed. Tests are performed on a series of 24 valves from two different MEMS sets. Focus is on the physical deformation of the structures under variable pressure loadings, as well as voltage levels. Other issues that inhibit proper performance of the valves are observed, addressed and documented as well. Many microfluidic applications have need for the distribution of gases at finely specified pressures and times. To this end a series of electrostatically actuated active valves have been fabricated. Eight separate silicon die are discussed, each with a series of four active valves present. The devices are designed such that the valve boss is held at a ground, with a voltage applied to lower contacts. Resulting electrostatic forces pull the boss down against a series of stops, intended to create a seal as well as prevent accidental shorting of the device. They have been uniquely packaged atop a stack of material layers, which have inlaid channels for application of fluid flow to the backside of the valve. Electrical contact is supplied from the underlying printed circuit board, attached to external supplies and along traces on the silicon. Pressure is supplied from a reservoir of house compressed air, up to 100 Psig. This is routed through a Norgren R07-200-RGKA pressure regulator, rated to 150 Psig. From there flow passes a manually operated ball valve, and to a flow meter. Two flow meters were utilized; initially an Omega FMA1802 rated at 10 sccm, and followed by a Flocat model for higher flow rates up to 100 sccm. An Omega DPG4000-500 pressure gauge produced pressure measurements. Optical measurements were returned via a WYKO Interferometry probe station. This would allow for determination of physical deformations of the device under a variety of voltage and pressure loads. This knowledge could lead to insight as to the failure mechanisms of the device

  14. Fast valve based on double-layer eddy-current repulsion for disruption mitigation in Experimental Advanced Superconducting Tokamak.

    PubMed

    Zhuang, H D; Zhang, X D

    2015-05-01

    A fast valve based on the double-layer eddy-current repulsion mechanism has been developed on Experimental Advanced Superconducting Tokamak (EAST). In addition to a double-layer eddy-current coil, a preload system was added to improve the security of the valve, whereby the valve opens more quickly and the open-valve time becomes shorter, making it much safer than before. In this contribution, testing platforms, open-valve characteristics, and throughput of the fast valve are discussed. Tests revealed that by choosing appropriate parameters the valve opened within 0.15 ms, and open-valve times were no longer than 2 ms. By adjusting working parameter values, the maximum number of particles injected during this open-valve time was estimated at 7 × 10(22). The fast valve will become a useful tool to further explore disruption mitigation experiments on EAST in 2015.

  15. Current status of valve replacement in children.

    PubMed

    Schaff, H V; Danielson, G K

    1986-01-01

    Management of valve diseases in children demands an eclectic approach by the surgeon. Whenever possible, valve function should be restored by repair rather than prosthetic replacement. Recent evidence firmly demonstrates that there are accelerated calcification and degeneration of porcine heterografts in children, especially in the aortic and mitral positions. For this reason, we reserve the use of heterograft prostheses for the right atrioventricular position and for conduits from the right ventricle to the pulmonary artery. Such patients are observed carefully for signs of valve degeneration. Long-term followup of the Starr-Edwards prosthesis in children demonstrates excellent durability and a thromboembolic rate that is equal to or lower than that found in adult patients. Hemodynamic properties of the Starr-Edwards valve are adequate even in the smallest size used in infants and have allowed children to reach early adolescence at which time valve re-replacement with an adult-sized prosthesis is possible. Intermediate-term experience with the Bjork-Shiley valve in children has also been favorable. At present we continue to use systemic anticoagulation with warfarin in all children with mechanical prostheses. PMID:3742534

  16. Placement of Neochords in Mitral Valve Repair: Enhanced Exposure of the Papillary Muscles Using a Standard Valve Sizer.

    PubMed

    Erlebach, Magdalena; Lange, Ruediger; Mazzitelli, Domenico

    2016-01-01

    Minimally invasive mitral valve repair with placement of artificial chordae for mitral valve regurgitation has become the standard of care. In some cases, such as Barlow's disease or bileaflet prolapse, papillary muscle exposure may be difficult. By using a valve sizer to retract both leaflets, visualization can be optimized, thus simplifying suture placement and thereby minimizing cross-clamp and cardiopulmonary bypass times. This technique is simple, is cost effective, and can be applied quickly. PMID:26694289

  17. Mitral valve prolapse

    MedlinePlus

    ... to keep blood from moving backwards when the heart beats (contracts). Mitral valve prolapse is the term used ... Dizziness Fatigue Panic attacks Sensation of feeling the heart beat ( palpitations ) Shortness of breath with activity or when ...

  18. Transcatheter Aortic Valve Implantation.

    PubMed

    Malaisrie, S Chris; Iddriss, Adam; Flaherty, James D; Churyla, Andrei

    2016-05-01

    Severe aortic stenosis (AS) is a life-threatening condition when left untreated. Aortic valve replacement (AVR) is the gold standard treatment for the majority of patients; however, transcatheter aortic valve implantation/replacement (TAVI/TAVR) has emerged as the preferred treatment for high-risk or inoperable patients. The concept of transcatheter heart valves originated in the 1960s and has evolved into the current Edwards Sapien and Medtronic CoreValve platforms available for clinical use. Complications following TAVI, including cerebrovascular events, perivalvular regurgitation, vascular injury, and heart block have decreased with experience and evolving technology, such that ongoing trials studying TAVI in lower risk patients have become tenable. The multidisciplinary team involving the cardiac surgeon and cardiologist plays an essential role in patient selection, procedural conduct, and perioperative care.

  19. Mitral Valve Prolapse.

    ERIC Educational Resources Information Center

    Bergy, Gordon G.

    1980-01-01

    Mitral valve prolapse is the most common heart disease seen in college and university health services. It underlies most arrhythmia and many chest complaints. Activity and exercise restrictions are usually unnecessary. (Author/CJ)

  20. Flow metering valve

    DOEpatents

    Blaedel, Kenneth L.

    1985-01-01

    An apparatus for metering fluids at high pressures of about 20,000 to 60,000 psi is disclosed. The apparatus includes first and second plates which are positioned adjacent each other to form a valve chamber. The plates are made of materials which have substantially equal elastic properties. One plate has a planar surface area, and the other a recessed surface area defined by periphery and central lips. When the two plates are positioned in adjacent contacting relationship, a valve chamber is formed between the planar surface area and the recessed surface area. Fluid is introduced into the chamber and exits therefrom when a deformation occurs at positions where they no longer form a valve seat. This permits the metering of fluids at high pressures and at slow variable rates. Fluid then exits from the chamber until an applied external force becomes large enough to bring the valve seats back into contact.

  1. Valve Repair or Replacement

    MedlinePlus

    ... valve surgery can be done using a robot. Robotic surgery does not require a large incision in ... The Texas Heart Institute has a robot. With robotic surgery, the surgeon has a control console, a ...

  2. Bidirectional piston valve

    DOEpatents

    Fischer, Harry C.

    1977-01-01

    This invention is a reversing valve having an inlet, an outlet, and an inlet-outlet port. The valve is designed to respond to the introduction of relatively high-pressure fluid at its inlet or, alternatively, of lower-pressure fluid at its inlet-outlet port. The valve includes an axially slidable assembly which is spring-biased to a position where it isolates the inlet and connects the inlet-outlet port to the outlet. The admission of high-pressure fluid to the inlet displaces the slidable assembly to a position where the outlet is isolated and the inlet is connected to the inlet-outlet port. The valve is designed to minimize pressure drops and leakage. It is of a reliable and comparatively simple design.

  3. THERMALLY OPERATED VAPOR VALVE

    DOEpatents

    Dorward, J.G. Jr.

    1959-02-10

    A valve is presented for use in a calutron to supply and control the vapor to be ionized. The invention provides a means readily operable from the exterior of the vacuum tank of the apparatuss without mechanical transmission of forces for the quick and accurate control of the ionizing arc by a corresponding control of gas flow theretos thereby producing an effective way of carefully regulating the operation of the calutron. The invention consists essentially of a tube member extending into the charge bottle of a calutron devices having a poppet type valve closing the lower end of the tube. An electrical heating means is provided in the valve stem to thermally vary the length of the stem to regulate the valve opening to control the flow of material from the charge bottle.

  4. Flow metering valve

    DOEpatents

    Blaedel, K.L.

    1983-11-03

    An apparatus for metering fluids at high pressures of about 20,000 to 60,000 psi is disclosed. The apparatus includes first and second plates which are positioned adjacent each other to form a valve chamber. The plates are made of materials which have substantially equal elastic properties. One plate has a planar surface area, and the other a recessed surface area defined by periphery and central lips. When the two plates are positioned in adjacent contacting relationship, a valve chamber is formed between the planar surface area and the recessed surface area. Fluid is introduced into the chamber and exits therefrom when a deformation occurs at positions where they no longer form a valve seat. This permits the metering of fluids at high pressures and at slow variable rates. Fluid then exits from the chamber until an applied external force becomes large enough to bring the valve seats back into contact.

  5. When a Mechanical Valve Goes Freestyle: A Patient Tailored Valve-In-Valve Implantation.

    PubMed

    François, J; Cathenis, K; Hamerlijnck, R

    2015-01-01

    In case of a redo operation after a full root replacement there are two possible options: replacing the entire root or performing a more conservative valve-in-valve implantation. Regarding the relatively high morbidity and mortality of a redo root replacement, the valve-in-valve implantation is the preferred choice if technically feasible. We present the case of a valve-in-valve implantation with a St. Jude mechanical valve in a Medtronic bioprosthesis in a 57-year old man. Follow-up echocardiography after 1 month showed a mean gradient of 17 mmHg and no paravalvular leakage. The combination of a St. Jude bileaflet mechanical valve implanted in a Freestyle root prosthesis has not been described. This case shows that patient tailored treatment with a St. Jude bileaflet mechanical valve in a Freestyle aortic root valve can be safely performed and might be the preferred choice for younger patients, if technically feasible. PMID:26560005

  6. Valve for gas centrifuges

    DOEpatents

    Hahs, Charles A.; Burbage, Charles H.

    1984-01-01

    The invention is a pneumatically operated valve assembly for simultaneously (1) closing gas-transfer lines connected to a gas centrifuge or the like and (2) establishing a recycle path between two of the lines so closed. The valve assembly is especially designed to be compact, fast-acting, reliable, and comparatively inexpensive. It provides large reductions in capital costs for gas-centrifuge cascades.

  7. VACUUM TRAP AND VALVE COMBINATION

    DOEpatents

    Milleron, N.; Levenson, L.

    1963-02-19

    This patent relates to a vacuum trap and valve combination suitable for use in large ultra-high vacuum systems. The vacuum trap is a chamber having an inlet and outlet opening which may be made to communicate with a chamber to be evacuated and a diffusion pump, respectively. A valve is designed to hermeticaliy seal with inlet opening and, when opened, block the line-of- sight'' between the inlet and outlet openings, while allowing a large flow path between the opened vaive and the side walls of the trap. The interior of the trap and the side of the valve facing the inlet opening are covered with an impurity absorbent, such as Zeolite or activated aluminum. Besides the advantage of combining two components of a vacuum system into one, the present invention removes the need for a baffle between the pump and the chamber to be evacuated. In one use of a specific embodiment of this invention, the transmission probability was 45 and the partial pressure of the pump fluid vapor in the vacuum chamber was at least 100 times lower than its vapor pressure. (AEC)

  8. Aortic valve replacement with sutureless and rapid deployment aortic valve prostheses.

    PubMed

    Berretta, Paolo; Di Eusanio, Marco

    2016-09-01

    Aortic valve stenosis is the most common valve disease in the western world. Over the past few years the number of aortic valve replacement (AVR) interventions has increased with outcomes that have been improved despite increasing age of patients and increasing burden of comorbidities. However, despite such excellent results and its well-established position, conventional AVR has undergone great development over the previous two decades. Such progress, by way of less invasive incisions and use of new technologies, including transcatheter aortic valve implantation and sutureless valve prostheses, is intended to reduce the traumatic impact of the surgical procedure, thus fulfilling lower risk patients' expectations on the one hand, and extending the operability toward increasingly high-risk patients on the other. Sutureless and rapid deployment aortic valves are biological, pericardial prostheses that anchor within the aortic annulus with no more than three sutures. The sutureless prostheses, by avoiding the passage and the tying of the sutures, significantly reduce operative times and may improve outcomes. However, there is still a paucity of robust, evidence-based data on the role and performance of sutureless AVR. Therefore, strongest long-term data, randomized studies and registry data are required to adequately assess the durability and long-term outcomes of sutureless aortic valve replacement. PMID:27582765

  9. Aortic valve replacement with sutureless and rapid deployment aortic valve prostheses

    PubMed Central

    Berretta, Paolo; Di Eusanio, Marco

    2016-01-01

    Aortic valve stenosis is the most common valve disease in the western world. Over the past few years the number of aortic valve replacement (AVR) interventions has increased with outcomes that have been improved despite increasing age of patients and increasing burden of comorbidities. However, despite such excellent results and its well-established position, conventional AVR has undergone great development over the previous two decades. Such progress, by way of less invasive incisions and use of new technologies, including transcatheter aortic valve implantation and sutureless valve prostheses, is intended to reduce the traumatic impact of the surgical procedure, thus fulfilling lower risk patients' expectations on the one hand, and extending the operability toward increasingly high-risk patients on the other. Sutureless and rapid deployment aortic valves are biological, pericardial prostheses that anchor within the aortic annulus with no more than three sutures. The sutureless prostheses, by avoiding the passage and the tying of the sutures, significantly reduce operative times and may improve outcomes. However, there is still a paucity of robust, evidence-based data on the role and performance of sutureless AVR. Therefore, strongest long-term data, randomized studies and registry data are required to adequately assess the durability and long-term outcomes of sutureless aortic valve replacement. PMID:27582765

  10. Actuator-valve interface optimization

    SciTech Connect

    Burchett, O.L.; Jones, R.L.

    1986-01-01

    A computer code, Actuator Valve Response (AVR), has been developed to optimize the explosive actuator-valve interface parameters so that the valve plunger velocity is at a maximum when the plunger reaches the valve tubes. The code considers three forces to act on the valve plunger before the plunger reaches the valve tubes. These are the pressure force produced by the actuator, the shear force necessary to shear the seal disks on the actuator and the valve plunger, and the friction force caused by friction between the plunger and the plunger bore. The three forces are modeled by expressions that are explicitly functions of the plunger displacement. A particular actuator-valve combination was analyzed with the computer code AVR with four different combinations of valve plunger seal disk shear strength and initial friction force. (LEW)

  11. Ceramic valve guide and seat

    SciTech Connect

    Mott, D.H.; Schmidt, H.

    1987-08-25

    For molded inclusion in a cast metal cylinder head of a internal combustion engine, an integral ceramic valve seat and valve stem guide assembly are described for operative engagement with and support of a conventional poppet-type valve with its enlarged head portion with a sealing surface thereon and an elongated cylindrical stem portion. The guide and seat consist of: valve seat forming means cast in ceramic material having an annular configuration operatively conforming to the configuration of the sealing surface of the valve and defining an annular seating surface for sealing engagement with the enlarged valve head when the valve is in a closed position; valve stem support means cast in ceramic having a generally tubular configuration with an internal bore and defining a support for reciprocation of the cylindrical stem portion of the valve as the valve moves between open and closed operative position; connecting means cast in ceramic and integral with both the valve set forming means and the valve stem supporting guide means for aligning the means so that a plane through the annular seating surface is normal to the axis of the tubular guide means and coaxially supporting the annular valve set forming means and the tubular guide portion whereas the integral valve seat forming means.

  12. Transcatheter aortic valve implantation.

    PubMed

    Nielsen, Hans Henrik Møller

    2012-12-01

    Transcatheter aortic valve implantation (TAVI) was introduced experimentally in 1989, based on a newly developed heart valve prosthesis - the stentvalve. The valve was invented by a Danish cardiologist named Henning Rud Andersen. The new valve was revolutionary. It was foldable and could be inserted via a catheter through an artery in the groin, without the need for heart lung machine. This allowed for a new valve implantation technique, much less invasive than conventional surgical aortic valve replacement (SAVR). Surgical aortic valve replacement is safe and improves symptoms along with survival. However, up to 1/3 of patients with aortic valve stenosis cannot complete the procedure due to frailty. The catheter technique was hoped to provide a new treatment option for these patients. The first human case was in 2002, but more widespread clinical use did not begin until 2006-2010. Today, in 2011, more than 40,000 valves have been implanted worldwide. Initially, because of the experimental character of the procedure, TAVI was reserved for patients who could not undergo SAVR due to high risk. The results in this group of patients were promising. The procedural safety was acceptable, and the patients experienced significant improvements in their symptoms. Three of the papers in this PhD-thesis are based on the outcome of TAVI at Skejby Hospital, in this high-risk population [I, II and IV]. Along with other international publications, they support TAVI as being superior to standard medical treatment, despite a high risk of prosthetic regurgitation. These results only apply to high-risk patients, who cannot undergo SAVR. The main purpose of this PhD study has been to investigate the quality of TAVI compared to SAVR, in order to define the indications for this new procedure. The article attached [V] describes a prospective clinical randomised controlled trial, between TAVI to SAVR in surgically amenable patients over 75 years of age with isolated aortic valve stenosis

  13. Comparison of accuracy of aortic valve area assessment in aortic stenosis by real time three-dimensional echocardiography in biplane mode versus two-dimensional transthoracic and transesophageal echocardiography.

    PubMed

    Blot-Souletie, Nathalie; Hébrard, Aurélien; Acar, Philippe; Carrié, Didier; Puel, Jacques

    2007-11-01

    Our aim was to validate the clinical feasibility of assessment of the area of the aortic valve orifice (AVA) by real time three-dimensional echocardiography (RT3DE) in biplane mode by planimetry and to compare it with the echo-Doppler methods more commonly used to evaluate valvular aortic stenosis (AS).RT3DE in biplane mode is a novel technique that allows operators to visualize the aortic valve orifice anatomy in any desired plane orientation. Its usefulness and accuracy have not previously been established. Using this technique, we studied a series of patients with AS and compared the results with those obtained by two-dimensional transesophageal echocardiography (TEE) planimetry and two-dimensional transthoracic echocardiography using the continuity equation (TTE-CE). RT3DE planimetries in biplane mode were measured by two independent observers. Bland-Altman analysis was used to compare these two methods.Forty-one patients with AS were enrolled in the study (15 women, 26 men, mean age 73.5 +/- 8.2 years). RT3DE planimetry was feasible in 92.7%. Average AVA determined by TTE-CE was 0.76 +/- 0.20 cm, by TEE planimetry 0.73 +/- 0.1 cm, and by RT3DE planimetry 0.76 +/- 0.20 cm(2). The average differences in AVA were-0.001 +/- 0.254 cm(2) and 0.03 +/- 0.155 cm(2) (RT3DE/TEE). The correlation coefficient for AVA (RT3DE/TTE-CE) was 0.82 and for AVA (RT3DE/TEE) it was 0.94, P < 0.0001. No significant intra- and interobserver variability was observed. In conclusion, RT3DE in biplane mode provides a feasible and reproducible method for measuring the area of the aortic valve orifice in aortic stenosis.

  14. Electromechanically Actuated Valve for Controlling Flow Rate

    NASA Technical Reports Server (NTRS)

    Patterson, Paul

    2007-01-01

    A proposed valve for controlling the rate of flow of a fluid would include an electric-motor-driven ball-screw mechanism for adjusting the seating element of the valve to any position between fully closed and fully open. The motor would be of a type that can be electronically controlled to rotate to a specified angular position and to rotate at a specified rate, and the ball screw would enable accurate linear positioning of the seating element as a function of angular position of the motor. Hence, the proposed valve would enable fine electronic control of the rate of flow and the rate of change of flow. The uniqueness of this valve lies in a high degree of integration of the actuation mechanism with the flow-control components into a single, relatively compact unit. A notable feature of this integration is that in addition to being a major part of the actuation mechanism, the ball screw would also be a flow-control component: the ball screw would be hollow so as to contain part of the main flow passage, and one end of the ball screw would be the main seating valve element. The relationships among the components of the valve are best understood by reference to the figure, which presents meridional cross sections of the valve in the fully closed and fully open positions. The motor would be supported by a bracket bolted to the valve body. By means of gears or pulleys and a timing belt, motor drive would be transmitted to a sleeve that would rotate on bearings in the valve body. A ball nut inside the sleeve would be made to rotate with the sleeve by use of a key. The ball screw would pass through and engage the ball nut. A key would prevent rotation of the ball screw in the valve body while allowing the ball screw to translate axially when driven by the ball nut. The outer surface of the ball screw would be threaded only in a mid-length region: the end regions of the outer surface of the ball screw would be polished so that they could act as dynamic sealing surfaces

  15. Valve performance concept move from preventive to condition-oriented maintenance

    SciTech Connect

    Zanner, G.; Kradepohl, P.

    1996-12-01

    As a turnkey supplier of nuclear and fossil power plants, Siemens must pay attention in concentrating, maintaining, and developing the expertise in many areas such as system design, components, materials, quality assurance, and qualification testing within centralized organizations. In the company segment VALVES, Siemens/KWU is staffed with experienced professionals who have serviced the power plant industry for about 25 years. The valve engineers deal with all kinds of valve and actuator-related activities like design ratings, development, qualifications, and ongoing improvements. In this regard, the engineers are involved in nearly all actual problems and suggested solutions through continuing dialogues with utilities, authorities, and vendors of valves and actuators.

  16. 9. BUTTERFLY VALVE CONTROL DIABLO POWERHOUSE. BUTTERFLY VALVES WERE MANUFACTURED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. BUTTERFLY VALVE CONTROL DIABLO POWERHOUSE. BUTTERFLY VALVES WERE MANUFACTURED BY THE PELTON WATER WHEEL COMPANY IN 1931, 1989. - Skagit Power Development, Diablo Powerhouse, On Skagit River, 6.1 miles upstream from Newhalem, Newhalem, Whatcom County, WA

  17. Pressure valve for needle gate valve control. June 13, 1913. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Pressure valve for needle gate valve control. June 13, 1913. Photocopy of original drawing. Drawing on file at the Salt River Project Archives. Phoenix, Arizona - Cross Cut Hydro Plant, North Side of Salt River, Tempe, Maricopa County, AZ

  18. Automatic Mesh Generation of Hybrid Mesh on Valves in Multiple Positions in Feedline Systems

    NASA Technical Reports Server (NTRS)

    Ross, Douglass H.; Ito, Yasushi; Dorothy, Fredric W.; Shih, Alan M.; Peugeot, John

    2010-01-01

    Fluid flow simulations through a valve often require evaluation of the valve in multiple opening positions. A mesh has to be generated for the valve for each position and compounding. The problem is the fact that the valve is typically part of a larger feedline system. In this paper, we propose to develop a system to create meshes for feedline systems with parametrically controlled valve openings. Herein we outline two approaches to generate the meshes for a valve in a feedline system at multiple positions. There are two issues that must be addressed. The first is the creation of the mesh on the valve for multiple positions. The second is the generation of the mesh for the total feedline system including the valve. For generation of the mesh on the valve, we will describe the use of topology matching and mesh generation parameter transfer. For generation of the total feedline system, we will describe two solutions that we have implemented. In both cases the valve is treated as a component in the feedline system. In the first method the geometry of the valve in the feedline system is replaced with a valve at a different opening position. Geometry is created to connect the valve to the feedline system. Then topology for the valve is created and the portion of the topology for the valve is topology matched to the standard valve in a different position. The mesh generation parameters are transferred and then the volume mesh for the whole feedline system is generated. The second method enables the user to generate the volume mesh on the valve in multiple open positions external to the feedline system, to insert it into the volume mesh of the feedline system, and to reduce the amount of computer time required for mesh generation because only two small volume meshes connecting the valve to the feedline mesh need to be updated.

  19. 46 CFR 193.15-16 - Lockout valves.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... lockout valve must be provided on any carbon dioxide extinguishing system protecting a space over 6,000... complete isolation of the system from the protected space or spaces, making it impossible for carbon... the valve is locked open at all times, except while maintenance is being performed on...

  20. Sliding pressure control valve for pneumatic hammer drill

    SciTech Connect

    Polsky, Yarom

    2011-08-30

    A pneumatic device control apparatus and method comprising a ported valve slidably fitted over a feed tube of the pneumatic device, and using a compliant biasing device to constrain motion of the valve to provide asymmetric timing for extended pressurization of a power chamber and reduced pressurization of a return chamber of the pneumatic device. The pneumatic device can be a pneumatic hammer drill.

  1. 49 CFR 192.181 - Distribution line valves.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE SAFETY TRANSPORTATION OF NATURAL AND OTHER GAS... time to shut down a section of main in an emergency. The valve spacing is determined by the operating... the flow or pressure of gas in a distribution system must have a valve installed on the inlet...

  2. Instantiating a mechatronic valve schedule for a hydrocephalus shunt.

    PubMed

    Momani, Lina; Alkharabsheh, Abdel Rahman; Al-Zuibi, Nayel; Al-Nuaimy, Waleed

    2009-01-01

    Hydrocephalus is caused by blockage or reabsorption difficulty that upsets the natural balance of production and absorption of cerebrospinal fluid in the brain, resulting in a build-up of the fluid in the ventricles of the brain. One of the recent advances in the treatment of hydrocephalus is the invention of a mechatronic valve. The desirability of such valve lies in the potential of having shunt that not only control hydrocephalus but also seeks to treat it. In contrast to current valves, such a valve is regulated based on a time based schedule not on the differential pressure across the valve. Thus the effectiveness of such valve is highly dependant on selecting an appropriate valve schedule that delivers personal dynamic treatment for every individual patient. Providing such a schedule is likely to be one of the obstacles facing the implementation of the mechatronic valve. In this paper, an algorithm is proposed to help in developing such a schedule that dynamically change based on the patients' own intracranial pressure data and a novel figure of merit, thus providing the physician with an easy tool that facilitate the use of the mechatronic valve. The algorithm was implemented in M ATLAB and Simulink. Real ICP data for three hydrocephalus patients (before shunting) were used to test this algorithm and the resulted schedules along with the resulted intracranial pressure data have illustrated the effectiveness of the algorithm in providing schedule that maintain ICP within the normal limits. PMID:19963474

  3. Seismic response for qualification of valves at nuclear plants

    SciTech Connect

    Bhargava, D.

    1996-12-01

    Power-operated valves constitute about a quarter to one-third of all safety-related components at a typical US nuclear plant. While extensive work has been done in the industry to quantify amplification factors for components such as electrical cabinets, little guidance is available to estimate amplification factors that can be applied to floor or piping anchor seismic response spectra to obtain valve responses. This paper establishes bounding amplification factors from which amplified response spectra and peak acceleration values can be obtained for the seismic qualification of valves. Parametric analyses of three representative nuclear piping systems consisting of different pipe sizes and support configurations are performed by the time-history method. Parameters such as the shape, frequency and energy content of the floor seismic spectra, peak shifting, size, weight and natural frequencies of the valves, support locations, and modal and spectral damping values are varied. Based on this study, amplified response spectra at the valve location for a variety of conditions are developed for each system. Amplification factors are then obtained by comparing spectra at the valve with the floor spectra. The peak seismic accelerations, which can be used in a valve`s static analysis, are automatically obtained form these results. They are, by definition, the zero period accelerations of the amplified response spectra at the valve.

  4. A high performance magnetorheological valve with a meandering flow path

    NASA Astrophysics Data System (ADS)

    Imaduddin, Fitrian; Amri Mazlan, Saiful; Rahman, Mohd Azizi Abdul; Zamzuri, Hairi; Ubaidillah; Ichwan, Burhanuddin

    2014-06-01

    The huge developments in the field of magnetorheological (MR) fluid-based devices will have a great influence on the future of mechatronic applications due to the ease of interfacing between electronic controls and the mechanical components that they provide. Among various MR fluid-based devices, an MR valve would be particularly significant for the development of other devices, if it could be successfully achieved. One of the most challenging obstacles to MR valve development is the difficulty of achieving device miniaturization while, at the same time, improving the achievable performance. This study demonstrates a novel design for an MR valve, using the meandering flow path approach in order to increase the effective area so that the MR fluid can be regulated within a small-sized valve. The meandering flow path is formed by combining multiple annular, radial and orifice flow channels. In order to analyze the valve performance, a mathematical model of the proposed MR valve is derived and combined with numerical simulation using the finite element method, with the intention of predicting the achievable pressure drop that can be generated by the valve. The predicted MR valve performances are then experimentally evaluated using an oscillation-disturbed bypass hydraulic cylinder. The simulation results show that the proposed MR valve design could yield substantial pressure drop improvement, which is confirmed by the experiment.

  5. Sutureless aortic valve replacement

    PubMed Central

    Phan, Kevin

    2015-01-01

    The increasing incidence of aortic stenosis and greater co-morbidities and risk profiles of the contemporary patient population has driven the development of minimally invasive aortic valve surgery and percutaneous transcatheter aortic valve implantation (TAVI) techniques to reduce surgical trauma. Recent technological developments have led to an alternative minimally invasive option which avoids the placement and tying of sutures, known as “sutureless” or rapid deployment aortic valves. Potential advantages for sutureless aortic prostheses include reducing cross-clamp and cardiopulmonary bypass (CPB) duration, facilitating minimally invasive surgery and complex cardiac interventions, whilst maintaining satisfactory hemodynamic outcomes and low paravalvular leak rates. However, given its recent developments, the majority of evidence regarding sutureless aortic valve replacement (SU-AVR) is limited to observational studies and there is a paucity of adequately-powered randomized studies. Recently, the International Valvular Surgery Study Group (IVSSG) has formulated to conduct the Sutureless Projects, set to be the largest international collaborative group to investigate this technology. This keynote lecture will overview the use, the potential advantages, the caveats, and current evidence of sutureless and rapid deployment aortic valve replacement (AVR). PMID:25870807

  6. Safety check valve

    SciTech Connect

    Spears, H.L.

    1992-02-11

    This patent describes a safety check valve, for use with a pumping unit for petroleum fluids, the pumping unit including a polished rod and a stuffing box. It comprises: a valve housing having upper and lower ends and a central bore extending between the upper and lower ends and adapted to have the polished rod pass through the central bore; a ball seating surface associated with the central bore; a non-spring bias ball; a ball housing for the ball and associated with the valve housing; and means for moving the ball from the ball housing into the central bore upon the polished rod not being disposed in the central bore, including a ball receiving cavity associated with the ball housing, the ball hoising having first and second ends, the first end of the ball housing being in communication with the central bore of the valve housing, the second end being closed; the ball receiving cavity having a ball support surface upon which the ball may rest, when the ball is disposed in the ball receiving cavity, the ball support surface sloping downwardly toward the first end of the ball housing, whereby if the polished rod is not disposed within the central bore of the valve housing, the ball moves down the ball support surface, under the force of gravity, from the ball receiving cavity into the central bore and seats on the ball seating surface.

  7. Fast closing valve

    DOEpatents

    Hanson, Clark L.

    1984-01-10

    A valve is provided for protecting the high vacuum of a particle accelera in the event of air leakage, wherein the valve provides an axially symmetrical passage to avoid disturbance of the partical beam during normal operation, and yet enables very rapid and tight closure of the beam-carrying pipe in the event of air leakage. The valve includes a ball member (30) which can rotate between a first position wherein a bore (32) in the member is aligned with the beam pipe, and a second position out of line with the pipe. A seal member (38) is flexibly sealed to the pipe, and has a seal end which can move tightly against the ball member after the bore has rotated out of line with the pipe, to thereby assure that the seal member does not retard rapid rotation of the ball valve member. The ball valve member can be rapidly rotated by a conductive arm (40) fixed to it and which is rotated by the discharge of a capacitor bank through coils (44, 45) located adjacent to the arm.

  8. Application of Model-based Prognostics to a Pneumatic Valves Testbed

    NASA Technical Reports Server (NTRS)

    Daigle, Matthew; Kulkarni, Chetan S.; Gorospe, George

    2014-01-01

    Pneumatic-actuated valves play an important role in many applications, including cryogenic propellant loading for space operations. Model-based prognostics emphasizes the importance of a model that describes the nominal and faulty behavior of a system, and how faulty behavior progresses in time, causing the end of useful life of the system. We describe the construction of a testbed consisting of a pneumatic valve that allows the injection of faulty behavior and controllable fault progression. The valve opens discretely, and is controlled through a solenoid valve. Controllable leaks of pneumatic gas in the testbed are introduced through proportional valves, allowing the testing and validation of prognostics algorithms for pneumatic valves. A new valve prognostics approach is developed that estimates fault progression and predicts remaining life based only on valve timing measurements. Simulation experiments demonstrate and validate the approach.

  9. Aortic valve surgery - minimally invasive

    MedlinePlus

    ... There are two main types of new valves: Mechanical, made of man-made materials, such as titanium ... Mechanical heart valves do not fail often. However, blood clots can develop on them. If a blood ...

  10. Locking apparatus for gate valves

    DOEpatents

    Fabyan, Joseph; Williams, Carl W.

    1988-01-01

    A locking apparatus for fluid operated valves having a piston connected to the valve actuator which moves in response to applied pressure within a cylinder housing having a cylinder head, a catch block is secured to the piston, and the cylinder head incorporates a catch pin. Pressure applied to the cylinder to open the valve moves the piston adjacent to the cylinder head where the catch pin automatically engages the catch block preventing futher movement of the piston or premature closure of the valve. Application of pressure to the cylinder to close the valve, retracts the catch pin, allowing the valve to close. Included are one or more selector valves, for selecting pressure application to other apparatus depending on the gate valve position, open or closed, protecting such apparatus from damage due to premature closing caused by pressure loss or operational error.

  11. Locking apparatus for gate valves

    DOEpatents

    Fabyan, J.; Williams, C.W.

    A locking apparatus for fluid operated valves having a piston connected to the valve actuator which moves in response to applied pressure within a cylinder housing having a cylinder head, a catch block is secured to the piston, and the cylinder head incorporates a catch pin. Pressure applied to the cylinder to open the valve moves the piston adjacent to the cylinder head where the catch pin automatically engages the catch block preventing further movement of the piston or premature closure of the valve. Application of pressure to the cylinder to close the valve, retracts the catch pin, allowing the valve to close. Included are one or more selector valves, for selecting pressure application to other apparatus depending on the gate valve position, open or closed, protecting such apparatus from damage due to premature closing caused by pressure loss or operational error.

  12. 46 CFR 196.30-20 - Breaking of safety valve seal.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Breaking of safety valve seal. 196.30-20 Section 196.30... OPERATIONS Reports of Accidents, Repairs, and Unsafe Equipment § 196.30-20 Breaking of safety valve seal. (a) If at any time it is necessary to break the seal on a safety valve for any purpose, the...

  13. 46 CFR 196.30-20 - Breaking of safety valve seal.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Breaking of safety valve seal. 196.30-20 Section 196.30... OPERATIONS Reports of Accidents, Repairs, and Unsafe Equipment § 196.30-20 Breaking of safety valve seal. (a) If at any time it is necessary to break the seal on a safety valve for any purpose, the...

  14. 40 CFR 61.242-6 - Standards: Open-ended valves or lines.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... end at all times except during operations requiring process fluid flow through the open-ended valve or... 40 Protection of Environment 8 2011-07-01 2011-07-01 false Standards: Open-ended valves or lines... for Equipment Leaks (Fugitive Emission Sources) § 61.242-6 Standards: Open-ended valves or lines....

  15. 77 FR 28669 - Pipeline Safety: Information Collection Activities, Excess Flow Valve Census

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-15

    ..., Excess Flow Valve Census AGENCY: Pipeline and Hazardous Materials Safety Administration (PHMSA), DOT..., PHMSA invites comments on a new one-time Information Collection (IC) on Excess Flow Valves (EFVs). PHMSA... Collection on Excess Flow Valves.'' In 1996, PHMSA's predecessor agency, the Research and Special...

  16. 40 CFR 61.242-6 - Standards: Open-ended valves or lines.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... end at all times except during operations requiring process fluid flow through the open-ended valve or... 40 Protection of Environment 8 2010-07-01 2010-07-01 false Standards: Open-ended valves or lines... for Equipment Leaks (Fugitive Emission Sources) § 61.242-6 Standards: Open-ended valves or lines....

  17. 40 CFR 63.1014 - Open-ended valves or lines standards.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... process fluid flow through the open-ended valve or line, or during maintenance. The operational provisions... valves but shall comply with paragraph (b)(1) of this section at all other times. (c) Emergency shutdown exemption. Open-ended valves or lines in an emergency shutdown system that are designed to...

  18. 46 CFR 196.30-20 - Breaking of safety valve seal.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Breaking of safety valve seal. 196.30-20 Section 196.30... OPERATIONS Reports of Accidents, Repairs, and Unsafe Equipment § 196.30-20 Breaking of safety valve seal. (a) If at any time it is necessary to break the seal on a safety valve for any purpose, the...

  19. 46 CFR 196.30-20 - Breaking of safety valve seal.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Breaking of safety valve seal. 196.30-20 Section 196.30... OPERATIONS Reports of Accidents, Repairs, and Unsafe Equipment § 196.30-20 Breaking of safety valve seal. (a) If at any time it is necessary to break the seal on a safety valve for any purpose, the...

  20. 46 CFR 196.30-20 - Breaking of safety valve seal.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Breaking of safety valve seal. 196.30-20 Section 196.30... OPERATIONS Reports of Accidents, Repairs, and Unsafe Equipment § 196.30-20 Breaking of safety valve seal. (a) If at any time it is necessary to break the seal on a safety valve for any purpose, the...

  1. Josephson magnetic rotary valve

    SciTech Connect

    Soloviev, I. I.; Klenov, N. V.; Bakurskiy, S. V.; Bol'ginov, V. V.; Ryazanov, V. V.; Kupriyanov, M. Yu.; Golubov, A. A.

    2014-12-15

    We propose a control element for a Josephson spin valve. It is a complex Josephson device containing ferromagnetic (F) layer in the weak-link area consisting of two regions, representing 0 and π Josephson junctions, respectively. The valve's state is defined by mutual orientations of the F-layer magnetization vector and boundary line between 0 and π sections of the device. We consider possible implementation of the control element by introduction of a thin normal metal layer in a part of the device area. By means of theoretical simulations, we study properties of the valve's structure as well as its operation, revealing such advantages as simplicity of control, high characteristic frequency, and good legibility of the basic states.

  2. Valve-spring Surge

    NASA Technical Reports Server (NTRS)

    Marti, Willy

    1937-01-01

    Test equipment is described that includes a system of three quartz indicators whereby three different pressures could be synchronized and simultaneously recorded on a single oscillogram. This equipment was used to test the reliction of waves at ends of valve spring, the dynamical stress of the valve spring for a single lift of the valve, and measurement of the curve of the cam tested. Other tests included simultaneous recording of the stress at both ends of the spring, spring oscillation during a single lift as a function of speed, computation of amplitude of oscillation for a single lift by harmonic analysis, effect of cam profile, the setting up of resonance, and forced spring oscillation with damping.

  3. Well valve control system

    SciTech Connect

    Schwendemann, K.L.; McCracken, O.W.; Mondon, C.G.; Wortham, L.C.

    1987-01-13

    A system is described for controlling well testing through an upper and lower test string with a subsea test tree connected therebetween and latch means to release the upper test string from the subsea test tree comprising: a. first and second selectively programmable microprocessor means; b. means for storing system operating limits in each microprocessor means; c. means for changing the operating limits in response to changes in well conditions; d. means for communicating operating fluid pressure to the subsurface test tree and the latch means; e. solenoid pilot valves controlling the flow of the operating fluid pressure to the subsea test tree and the latch means; f. the first microprocessor means located at a central control console; g. the second microprocessor means located near the solenoid valves; h. means for transmitting signals between the first and second microprocessor means and validating the accuracy of the signals; and i. electronic circuits to control operation of the solenoid valves in response to validated signals.

  4. Mitral valve prolapse.

    PubMed

    Guy, T Sloane; Hill, Arthur C

    2012-01-01

    Mitral valve prolapse is defined as abnormal bulging of the mitral valve leaflets into the left atrium during ventricular systole. Mitral valve prolapse is a common condition that is a risk factor for mitral regurgitation, congestive heart failure, arrhythmia, and endocarditis. Myxomatous degeneration is the most common cause of mitral prolapse in the United States and Europe, and progression of myxomatous mitral prolapse is the most common cause of mitral regurgitation that requires surgical treatment. Myxomatous degeneration appears to have genetic etiology. The genetics of myxomatous degeneration is complex and not fully worked out; it appears to be heterogeneous with multi-gene, multi-chromosomal autosomal dominance with incomplete penetrance. The molecular disorder of myxomatous degeneration appears to consist of a connective tissue disorder with altered extracellular matrix status and involves the action of matrix metalloproteinase, cysteine endoproteases, and tenomodulin. Treatment of mitral prolapse with regurgitation is complex, and the technological advances that are currently in development will be challenging and controversial.

  5. Hydrogen gas relief valve

    DOEpatents

    Whittlesey, Curtis C.

    1985-01-01

    An improved battery stack design for an electrochemical system having at least one cell from which a gas is generated and an electrolyte in communication with the cell is described. The improved battery stack design features means for defining a substantially closed compartment for containing the battery cells and at least a portion of the electrolyte for the system, and means in association with the compartment means for selectively venting gas from the interior of the compartment means in response to the level of the electrolyte within the compartment means. The venting means includes a relief valve having a float member which is actuated in response to the level of the electrolyte within the compartment means. This float member is adapted to close the relief valve when the level of the electrolyte is above a predetermined level and open the relief valve when the level of electrolyte is below this predetermined level.

  6. 46 CFR 154.544 - Quick-closing shut-off valves.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Quick-closing shut-off valves. 154.544 Section 154.544... and Process Piping Systems § 154.544 Quick-closing shut-off valves. The quick-closing shut-off valve under §§ 154.530, 154.532 and 154.538 must: (a) Be a shut-off valve; (b) Close from the time...

  7. 46 CFR 154.544 - Quick-closing shut-off valves.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Quick-closing shut-off valves. 154.544 Section 154.544... and Process Piping Systems § 154.544 Quick-closing shut-off valves. The quick-closing shut-off valve under §§ 154.530, 154.532 and 154.538 must: (a) Be a shut-off valve; (b) Close from the time...

  8. Automatic monitoring of valve status

    SciTech Connect

    Prinz, F.B.; Chern, J.H.

    1989-06-01

    Authors propose establishing the relationship between valve leaking and thermal gradient to allow detection of valve leakage by observing the piping system`s temperature profile and using an expert system to infer the valve condition. They describe their work toward this and their January 1988 report thereon. The authors also suggest designing modem power plants to accommodate a remotely controlled or autonomous vehicle which would carry a device for thermal-gradient leak detection to examine valves in situ.

  9. Self-regulating valve

    DOEpatents

    Humphreys, D.A.

    1982-07-20

    A variable, self-regulating valve having a hydraulic loss coefficient proportional to a positive exponential power of the flow rate. The device includes two objects in a flow channel and structure which assures that the distance between the two objects is an increasing function of the flow rate. The range of spacing between the objects is such that the hydraulic resistance of the valve is an increasing function of the distance between the two objects so that the desired hydraulic loss coefficient as a function of flow rate is obtained without variation in the flow area.

  10. Tide gate valve

    SciTech Connect

    Raftis, S. G.

    1985-01-08

    A tide gate check valve in which at least three converging sides are provided at a tapered region of a flexible sleeve, so that on reverse back pressure build-up of fluid, reverse fluid flow is prevented, while the valve sleeve does not invert or collapse. The present configuration features embedded reinforcing elements for resisting inversion or collapsing when the back pressure builds up. This feature is especially important for large-sized conduits of 36'' or 72'' diameter, or even larger, such as are common in storm sewer applications.

  11. Lightweight Valve Closes Duct Quickly

    NASA Technical Reports Server (NTRS)

    Fournier, Walter L.; Burgy, N. Frank

    1991-01-01

    Expanding balloon serves as lightweight emergency valve to close wide duct. Uninflated balloon stored in housing of duct. Pad resting on burst diaphragm protects balloon from hot gases in duct. Once control system triggers valve, balloon inflates rapidly to block duct. Weighs much less than does conventional butterfly, hot-gas, or poppet valve capable of closing duct of equal diameter.

  12. Valve stem and packing assembly

    DOEpatents

    Wordin, John J.

    1991-01-01

    A valve stem and packing assembly is provided in which a rotatable valve stem includes a first tractrix surface for sliding contact with a stem packing and also includes a second tractrix surface for sliding contact with a bonnet. Force is applied by means of a spring, gland flange, and gland on the stem packing so the stem packing seals to the valve stem and bonnet. This configuration serves to create and maintain a reliable seal between the stem packing and the valve stem. The bonnet includes a second complementary tractrix surface for contacting the second sliding tractrix surface, the combination serving as a journal bearing for the entire valve stem and packing assembly. The journal bearing so configured is known as a Schiele's pivot. The Schiele's pivot also serves to maintain proper alignment of the valve stem with respect to the bonnet. Vertical wear between the surfaces of the Schiele's pivot is uniform at all points of contact between the second sliding tractrix surface and the second complementary tractrix surface of a bonnet. The valve stem is connected to a valve plug by means of a slip joint. The valve is opened and closed by rotating the valve stem. The slip joint compensates for wear on the Schiele's pivot and on the valve plug. A ledge is provided on the valve bonnet for the retaining nut to bear against. The ledge prevents overtightening of the retaining nut and the resulting excessive friction between stem and stem packing.

  13. Valve stem and packing assembly

    DOEpatents

    Wordin, J.J.

    1991-09-03

    A valve stem and packing assembly is provided in which a rotatable valve stem includes a first tractrix surface for sliding contact with a stem packing and also includes a second tractrix surface for sliding contact with a bonnet. Force is applied by means of a spring, gland flange, and gland on the stem packing so the stem packing seals to the valve stem and bonnet. This configuration serves to create and maintain a reliable seal between the stem packing and the valve stem. The bonnet includes a second complementary tractrix surface for contacting the second sliding tractrix surface, the combination serving as a journal bearing for the entire valve stem and packing assembly. The journal bearing so configured is known as a Schiele's pivot. The Schiele's pivot also serves to maintain proper alignment of the valve stem with respect to the bonnet. Vertical wear between the surfaces of the Schiele's pivot is uniform at all points of contact between the second sliding tractrix surface and the second complementary tractrix surface of a bonnet. The valve stem is connected to a valve plug by means of a slip joint. The valve is opened and closed by rotating the valve stem. The slip joint compensates for wear on the Schiele's pivot and on the valve plug. A ledge is provided on the valve bonnet for the retaining nut to bear against. The ledge prevents over tightening of the retaining nut and the resulting excessive friction between stem and stem packing. 2 figures.

  14. Prosthetic Valve Thrombosis: Diagnosis and Management.

    PubMed

    Garg, Jalaj; Palaniswamy, Chandrasekar; Pinnamaneni, Sowmya; Sarungbam, Judy; Jain, Diwakar

    2016-01-01

    St. Jude mechanical prosthesis is the most commonly used prosthetic device with least valvular complications with excellent hemodynamics. However, prosthetic valve thrombosis is one of the serious complications, with rates between 0.03% and 0.13% per patient-year depending on the type of anticoagulation used and compliance to the therapy. Transthoracic echocardiography (TTE) is the initial screening tool (class I) that would provide clues for the assessment of valvular hemodynamics. Fluoroscopy is an alternate imaging modality for the assessment of mechanical leaflet motion, especially in patients when prosthetic valves are difficult to image on TTE or transesophageal echocardiography. A complete fluoroscopic evaluation of a prosthetic valve includes assessment of valvular motion and structural integrity. Opening and closing angles can be measured fluoroscopically to determine whether a specific valve is functioning properly. We discuss a case of a 91-year-old man with thrombosis of bileaflet mechanical mitral prosthesis that was demonstrated on real-time fluoroscopy (not evident on TTE). An algorithmic approach to diagnosis and management of prosthetic heart valve thrombosis is outlined. PMID:25486519

  15. Cylinder To Cylinder Balancing Using Intake Valve Actuation

    DOEpatents

    Duffy, Kevin P.; Kieser, Andrew J.; Kilkenny, Jonathan P.

    2005-01-18

    A method and apparatus for balancing a combustion phasing between a plurality of cylinders located in an engine. The method and apparatus includes a determining a combustion timing in each cylinder, establishing a baseline parameter for a desired combustion timing, and varying actuation of at least one of a plurality of intake valves, each intake valve being in fluid communication with a corresponding cylinder, such that the combustion timing in each cylinder is substantially equal to the desired combustion timing.

  16. Electromagnetically driven, fast opening and closing gas jet valve

    NASA Astrophysics Data System (ADS)

    Krishnan, Mahadevan; Elliott, Kristi Wilson; Geddes, C. G. R.; van Mourik, R. A.; Leemans, W. P.; Murphy, H.; Clover, M.

    2011-03-01

    The design and performance are presented of an electromagnetically driven gas valve [M. Krishnan, J. Wright, and T. Ma, Proceedings of the 13th Advanced Accelerator Concepts Workshop, Santa Cruz, CA, AIP Conf. Proc. No. 1086 (AIP, New York, 2008)] that opens in <100μs, closes in <500μs, and can operate at pressures of ˜1000psia to drive supersonic nozzles. Such a valve has applications to laser-plasma accelerators, where the fast opening and closing would allow sharper edges to the flow and also allow higher rep-rate operation without loading the vacuum chamber. The valve action is effected by a flyer plate accelerated by the electromagnetic impulse of a low inductance, spiral wound, strip-line coil driven by a capacitor. Gas flows out of the valve when the seal between this flyer plate and the valve seat is broken. The electromagnetic force greatly exceeds the restoring forces provided by a spring and the gas pressure against the valve seat. Piezoresistive sensor and laser interferometer measurements of flow show that the valve opens in ˜100μs for all pressures up to 800 psia. The closing time is 500μs, set by the spring constant and mass. The prototype valve has been operated with helium at 0.5 Hz and at 500 psia for ˜1 hour at a time with no cooling.

  17. Comment on 'Shang S. 2012. Calculating actual crop evapotranspiration under soil water stress conditions with appropriate numerical methods and time step. Hydrological Processes 26: 3338-3343. DOI: 10.1002/hyp.8405'

    NASA Technical Reports Server (NTRS)

    Yatheendradas, Soni; Narapusetty, Balachandrudu; Peters-Lidard, Christa; Funk, Christopher; Verdin, James

    2014-01-01

    A previous study analyzed errors in the numerical calculation of actual crop evapotranspiration (ET(sub a)) under soil water stress. Assuming no irrigation or precipitation, it constructed equations for ET(sub a) over limited soil-water ranges in a root zone drying out due to evapotranspiration. It then used a single crop-soil composite to provide recommendations about the appropriate usage of numerical methods under different values of the time step and the maximum crop evapotranspiration (ET(sub c)). This comment reformulates those ET(sub a) equations for applicability over the full range of soil water values, revealing a dependence of the relative error in numerical ET(sub a) on the initial soil water that was not seen in the previous study. It is shown that the recommendations based on a single crop-soil composite can be invalid for other crop-soil composites. Finally, a consideration of the numerical error in the time-cumulative value of ET(sub a) is discussed besides the existing consideration of that error over individual time steps as done in the previous study. This cumulative ET(sub a) is more relevant to the final crop yield.

  18. Improved Merge Valve

    NASA Technical Reports Server (NTRS)

    George-Falvy, Dez

    1992-01-01

    Circumferential design combines compactness and efficiency. In remotely controlled valve, flow in tributary duct along circumference of primary duct merged with flow in primary duct. Flow in tributary duct regulated by variable throat nuzzle driven by worm gear. Design leak-proof, and most components easily fabricated on lathe.

  19. Valve for cryogenic service

    DOEpatents

    Worwetz, H.A.

    1975-09-02

    This patent relates to a valve for use with a liquefied gas at cryogenic temperatures in which a pair of joined knife edges are bellows controlled to contact an indium alloy seat in an annular slot when flow is to be stopped. The sealing alloy may be renewed by heating in situ. (auth)

  20. Vent Relief Valve Test

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Shown is the disassembly, examination, refurbishment and testing of the LH2 ( liquid hydrogen) and LOX (liquid oxygen) vent and relief valves for the S-IVB-211 engine stage in support of the Constellation/Ares project. This image is extracted from high definition video and is the highest resolution available.

  1. Eustachian valve endocarditis.

    PubMed Central

    Vilacosta, I; San Roman, J A; Roca, V

    1990-01-01

    M mode and cross sectional echocardiography showed a highly mobile globular pedunculated mass(3.0 cm long with a maximum diameter of i.5 cm) attached to the eustachian valve in a heroin addict with staphylococcal endocarditis. Images Figure 1 Figure 2 PMID:2245118

  2. Valve for gas centrifuges

    DOEpatents

    Hahs, C.A.; Rurbage, C.H.

    1982-03-17

    The invention is pneumatically operated valve assembly for simulatenously (1) closing gas-transfer lines connected to a gas centrifuge or the like and (2) establishing a recycle path between two on the lines so closed. The value assembly is especially designed to be compact, fast-acting, reliable, and comparatively inexpensive. It provides large reductions in capital costs for gas-centrifuge cascades.

  3. TUBE SHEARING VALVE

    DOEpatents

    Wilner, L.B.

    1960-05-24

    Explosive operated valves can be used to join two or more containers in fluid flow relationship, one such container being a sealed reservoir. The valve is most simply disposed by mounting it on the reservoir so thst a tube extends from the interior of the reservoir through the valve body, terminating at the bottom of the bore in a closed end; other containers may be similarly connected or may be open connected, as desired. The piston of the valve has a cutting edge at its lower end which shears off the closed tube ends and a recess above the cutting edge to provide a flow channel. Intermixing of the fluid being transferred with the explosion gases is prevented by a copper ring at the top of the piston which is force fitted into the bore at the beginning of the stroke. Although designed to avoid backing up of the piston at pressures up to 10,000 psi in the transferred fluid, proper operation is independent of piston position, once the tube ends were sheared.

  4. EVALUATION OF SPRING OPERATED RELIEF VALVE MAINTENANCE INTERVALS AND EXTENSION OF MAINTENANCE TIMES USING A WEIBULL ANALYSIS WITH MODIFIED BAYESIAN UPDATING

    SciTech Connect

    Harris, S.; Gross, R.; Mitchell, E.

    2011-01-18

    The Savannah River Site (SRS) spring operated pressure relief valve (SORV) maintenance intervals were evaluated using an approach provided by the American Petroleum Institute (API RP 581) for risk-based inspection technology (RBI). In addition, the impact of extending the inspection schedule was evaluated using Monte Carlo Simulation (MCS). The API RP 581 approach is characterized as a Weibull analysis with modified Bayesian updating provided by SRS SORV proof testing experience. Initial Weibull parameter estimates were updated as per SRS's historical proof test records contained in the Center for Chemical Process Safety (CCPS) Process Equipment Reliability Database (PERD). The API RP 581 methodology was used to estimate the SORV's probability of failing on demand (PFD), and the annual expected risk. The API RP 581 methodology indicates that the current SRS maintenance plan is conservative. Cost savings may be attained in certain mild service applications that present low PFD and overall risk. Current practices are reviewed and recommendations are made for extending inspection intervals. The paper gives an illustration of the inspection costs versus the associated risks by using API RP 581 Risk Based Inspection (RBI) Technology. A cost effective maintenance frequency balancing both financial risk and inspection cost is demonstrated.

  5. Multi-port valve assembly

    DOEpatents

    Guggenheim, S. Frederic

    1986-01-01

    A multi-port fluid valve apparatus is used to control the flow of fluids through a plurality of valves and includes a web, which preferably is a stainless steel endless belt. The belt has an aperture therethrough and is progressed, under motor drive and control, so that its aperture is moved from one valve mechanism to another. Each of the valve mechanisms comprises a pair of valve blocks which are held in fluid-tight relationship against the belt. Each valve block consists of a block having a bore through which the fluid flows, a first seal surrounding the bore and a second seal surrounding the first seal, with the distance between the first and second seals being greater than the size of the belt aperture. In order to open a valve, the motor progresses the belt aperture to where it is aligned with the two bores of a pair of valve blocks, such alignment permitting a flow of the fluid through the valve. The valve is closed by movement of the belt aperture and its replacement, within the pair of valve blocks, by a solid portion of the belt.

  6. International Expert Consensus on Sutureless and Rapid Deployment Valves in Aortic Valve Replacement Using Minimally Invasive Approaches

    PubMed Central

    Glauber, Mattia; Moten, Simon C.; Quaini, Eugenio; Solinas, Marco; Folliguet, Thierry A.; Meuris, Bart; Miceli, Antonio; Oberwalder, Peter J.; Rambaldini, Manfredo; Teoh, Kevin H. T.; Bhatnagar, Gopal; Borger, Michael A.; Bouchard, Denis; Bouchot, Olivier; Clark, Stephen C.; Dapunt, Otto E.; Ferrarini, Matteo; Fischlein, Theodor J. M.; Laufer, Guenther; Mignosa, Carmelo; Millner, Russell; Noirhomme, Philippe; Pfeiffer, Steffen; Ruyra-Baliarda, Xavier; Shrestha, Malakh Lal; Suri, Rakesh M.; Troise, Giovanni; Gersak, Borut

    2016-01-01

    Objective To define the benefit of sutureless and rapid deployment valves in current minimally invasive approaches in isolated aortic valve replacement. Methods A panel of 28 international experts with expertise in both minimally invasive aortic valve replacement and rapid deployment valves was constituted. After thorough literature review, the experts rated evidence-based recommendations in a modified Delphi approach. Results No guideline could be retrieved. Thirty-three clinical trials and 9 systematic reviews could be identified for detailed text analysis to obtain a total of 24 recommendations. After rating by the experts 12, final recommendations were identified: preoperative computed tomographic scan as well as intraoperative transesophageal echocardiography are highly recommended. Suitable annular sizes are 19 to 27 mm. There is a contraindication for bicuspid valves only for type 0 and for annular abscess or destruction due to infective endocarditis. The use of sutureless and rapid deployment valves reduces extracorporeal circulation and aortic cross-clamp time and leads to less early complications as prolonged ventilation, blood transfusion, atrial fibrillation, pleural effusions, paravalvular leakages and aortic regurgitation, and renal replacement therapy, respectively. These clinical outcomes result in reduced intensive care unit and hospital stay and reduced costs. The use of sutureless and rapid deployment valves will lead to a higher adoption rate of minimally invasive approaches in aortic valve replacement. Respect should be taken to a necessary short learning curve for both sutureless and minimally invasive programs. Conclusions Sutureless and rapid deployment aortic valve replacement together with minimally invasive approaches offers an attractive option in aortic valve placement for patients requiring biological valve replacement. PMID:27540996

  7. Field test comparison of natural gas engine exhaust valves

    SciTech Connect

    Bicknell, W.B.; Hay, S.C.; Shade, W.N.; Statler, G.R.

    1996-12-31

    As part of a product improvement program, an extensive spark-ignited, turbocharged, natural gas engine exhaust valve test program was conducted using laboratory and field engines. Program objectives were to identify a valve and seat insert combination that increased mean time between overhauls (MTBO) while reducing the risk of premature valve cracking and failure. Following a thorough design review, a large number of valve and seat insert configurations were tested in a popular 900 RPM, 166 BHP (0.123 Mw) per cylinder industrial gas engine series. Material, head geometry, seat angle and other parameters were compared. Careful in-place measurements and post-test inspections compared various configurations and identified optimal exhaust valving for deployment in new units and upgrades of existing engines.

  8. Mechanical valve obstruction: Review of diagnostic and treatment strategies

    PubMed Central

    Salamon, Jason; Munoz-Mendoza, Jerson; Liebelt, Jared J; Taub, Cynthia C

    2015-01-01

    Prosthetic valve obstruction (PVO) is a rare but feared complication of mechanical valve replacement. Diagnostic evaluation should focus on differentiating prosthetic valve thrombosis (PVT) from pannus formation, as their treatment options differ. History of sub-optimal anti-coagulation and post-op time course to development of PVO are useful clinical characteristics in differentiating thrombus from pannus formation. Treatment of PVT is influenced by the patient’s symptoms, valve location, degree of obstruction and thrombus size and may include thrombolysis or surgical intervention. Alternatively, pannus formation requires surgical intervention. The purpose of this article is to review the pathophysiology, epidemiology, diagnostic approach and treatment options for aortic and mitral valve PVO. PMID:26730292

  9. Micro-valve pump light valve display

    DOEpatents

    Yeechun Lee.

    1993-01-19

    A flat panel display incorporates a plurality of micro-pump light valves (MLV's) to form pixels for recreating an image. Each MLV consists of a dielectric drop sandwiched between substrates, at least one of which is transparent, a holding electrode for maintaining the drop outside a viewing area, and a switching electrode from accelerating the drop from a location within the holding electrode to a location within the viewing area. The sustrates may further define non-wetting surface areas to create potential energy barriers to assist in controlling movement of the drop. The forces acting on the drop are quadratic in nature to provide a nonlinear response for increased image contrast. A crossed electrode structure can be used to activate the pixels whereby a large flat panel display is formed without active driver components at each pixel.

  10. Micro-valve pump light valve display

    DOEpatents

    Lee, Yee-Chun

    1993-01-01

    A flat panel display incorporates a plurality of micro-pump light valves (MLV's) to form pixels for recreating an image. Each MLV consists of a dielectric drop sandwiched between substrates, at least one of which is transparent, a holding electrode for maintaining the drop outside a viewing area, and a switching electrode from accelerating the drop from a location within the holding electrode to a location within the viewing area. The sustrates may further define non-wetting surface areas to create potential energy barriers to assist in controlling movement of the drop. The forces acting on the drop are quadratic in nature to provide a nonlinear response for increased image contrast. A crossed electrode structure can be used to activate the pixels whereby a large flat panel display is formed without active driver components at each pixel.

  11. Torque characteristics of a 122-centimeter butterfly valve with a hydro/pneumatic actuator

    NASA Technical Reports Server (NTRS)

    Lin, F. N.; Moore, W. I.; Lundy, F. E.

    1981-01-01

    Actuating torque data from field testing of a 122-centimeter (48 in.) butterfly valve with a hydro/pneumatic actuator is presented. The hydraulic cylinder functions as either a forward or a reverse brake. Its resistance torque increases when the valve speeds up and decreases when the valve slows down. A reduction of flow resistance in the hydraulic flow path from one end of the hydraulic cylinder to the other will effectively reduce the hydraulic resistance torque and hence increase the actuating torque. The sum of hydrodynamic and friction torques (combined resistance torque) of a butterfly valve is a function of valve opening time. An increase in the pneumatic actuating pressure will result in a decrease in both the combined resistance torque and the actuator opening torque; however, it does shorten the valve opening time. As the pneumatic pressure increases, the valve opening time for a given configuration approaches an asymptotical value.

  12. Design, maintenance extend FGD system slurry valve life

    SciTech Connect

    LeMay, B.; Willyard, B.; Polasek, S.; Clarkson, C.W.

    1995-08-01

    This article describes how power plants in Florida, Oklahoma and Texas adopted improved maintenance techniques and sought better design criteria to gain greater slurry valve reliability. Slurry valves, a vital part of a flue gas desulfurization (FGD) system, are critical to a power plant`s ability to meet or exceed acid rain emission requirements. The performance and reliability of these valves can significantly affect unit operation and load capacity. For example, slurry valves installed on the suction and discharge ends of scrubber tower pumps are a main point of isolation. When these valves malfunction, the scrubber tower must be shut down. Problems with valves that control the feed system and reaction tank alter slurry pH and density, and also affect unit load. In addition, a single valve that serves dual-pumping systems from the slurry storage tank to the reaction tank can cause a system outage. Because of their key role in system operation, specific maintenance approaches were developed at several power plants to improve slurry valve reliability and run times.

  13. Factors affecting the valve movements in freshwater unionids

    SciTech Connect

    Pynnoenen, K.S.; Englund, V.P.M.

    1994-12-31

    In order to avoid harmful conditions, freshwater unionids are able to close their valves and to resist extended long periods of complete anoxia. Xenobiotics and diverse abiotic and biotic factors can change the rhythm of valve movements and thus affect the accumulation of heavy metals in these bivalves. When bivalves are used a bioindicators in the field and when the accumulation of toxicants are studied under the laboratory conditions, the effects of valve movements and shell closure have to be involved. In this study, the authors have recorded valve movements of two different unionid species (Anodonta anatina, Unio tumidus) in the field and in the laboratory using a digital monitoring system. Several experimental arrangements were compared (caged mussels vs. sediment dwelling mussels, flow-through vials vs. static aquaria with and without sediment). Some parameters of the mussel hemolymph, such as electrolytes, gases and acid base status, were compared with the results on the valve activity (time with valves open, number of adductions). The natural valve activity of the two unionid species differed clearly. In the field, effects of transfer and caging were found, and in the laboratory, sediment and water flow changed their behavior. The level of the blood oxygen was most affected, whereas, the acid-base status and the concentrations of electrolytes were effectively regulated by the unionids. The correlation between valve movements and the hemolymph parameters was weaker than expected.

  14. Classification of heart valve condition using acoustic measurements

    SciTech Connect

    Clark, G.

    1994-11-15

    Prosthetic heart valves and the many great strides in valve design have been responsible for extending the life spans of many people with serious heart conditions. Even though the prosthetic valves are extremely reliable, they are eventually susceptible to long-term fatigue and structural failure effects expected from mechanical devices operating over long periods of time. The purpose of our work is to classify the condition of in vivo Bjork-Shiley Convexo-Concave (BSCC) heart valves by processing acoustic measurements of heart valve sounds. The structural failures of interest for Bscc valves is called single leg separation (SLS). SLS can occur if the outlet strut cracks and separates from the main structure of the valve. We measure acoustic opening and closing sounds (waveforms) using high sensitivity contact microphones on the patient`s thorax. For our analysis, we focus our processing and classification efforts on the opening sounds because they yield direct information about outlet strut condition with minimal distortion caused by energy radiated from the valve disc.

  15. Trends in development of automatically controlled pipeline valves

    SciTech Connect

    Popov, N.P.; Il`in, A.Yu.

    1994-07-01

    One of the directions being taken in the field of modern chemical and petroleum machinery construction is the design of reliable, cost-competitive, electrically and actuated valves for pipelines and automatic control systems (ACS) for such valves. The requirements imposed on reliability and quality in the manufacture of automatically controlled pipeline valves are becoming more and more stringent. In order to determine the factors influencing valve reliability indexes, a study was made of a batch of valves with nominal diameter D = 100 mm and rated pressure p = 1.6 MPa, with metal-to-metal seating. It was found that with a seating force corresponding to the design value, initial leakage was observed after 3270 cycles, and with a 140% increase after 2740 cycles. The probability of trouble-free operation of these valves during the course of the guaranteed life (3300 cycles) decreases from 0.999 under the design conditions to 0.79 when the seating force is increased by 60% above the design value. The main factors contributing to greater seating force in comparison with the nominal (design) value are the rigidity of the valve/drive system (determined by the valve design, the type of seating contact, and the construction of the electric drive), the moment of inertia of the rotating parts in the drive, the accuracy of adjustment of the drive, and the response time of the drive when actuated by the ACS.

  16. Mitral valve repair at the time of continuous-flow left ventricular assist device implantation confers meaningful decrement in pulmonary vascular resistance.

    PubMed

    Taghavi, Sharven; Hamad, Eman; Wilson, Lynn; Clark, Rachael; Jayarajan, Senthil N; Uriel, Nir; Goldstein, Daniel J; Takayama, Hiroo; Naka, Yoshifumi; Mangi, Abeel A

    2013-01-01

    We hypothesized that the addition of mitral valve replacement or repair (MVR) to implantation of continuous-flow left ventricular assist device (cf-LVAD) may further decrease pulmonary vascular resistance (PVR) over Heartmate II (HMII) implantation alone. Patients undergoing MVR with concomitant HMII implantation were compared with those undergoing HMII implantation alone. Of the 57 patients undergoing cf-LVAD implantation, 21 (36.8%) underwent concomitant MVR and 36 (63.2%) underwent cf-LVAD implantation alone. Patients receiving MVR had greater decrement in PVR (59.4% vs. 35.2%, p = 0.01). Decrease in end-diastolic diameter was greater for patients receiving MVR but did not reach statistical significance (18.2 vs. 13.5 mm, p = 0.33). Duration of mechanical ventilation (121.6 vs. 181.4 hours, p = 0.45) and inotropic support (162.4 vs. 153.2 hours, p = 0.86), change in creatinine (0.19 vs. -0.26 mg/dl, p = 0.34), increase in bilirubin (2.54 vs. 1.55 mg/dl, p = 0.63), intensive care unit stay (168.0 vs. 231.5 hours, p = 0.38), and overall length of stay (32.0 vs. 42.5 days, p = 0.75) were similar. There was no difference in survival at 3 months (89.7% vs. 83.3%) and 1 year (83.7 vs. 67.3%, p = 0.34). Addition of MVR may result in greater decrement of PVR than HMII implantation alone. This may permit certain patients thought to be ineligible for transplantation to become candidates.

  17. Valve-in-valve transcatheter aortic valve implantation overcoming hostile anatomy: Evolut R for the treatment of Mitroflow bioprosthesis dysfunction.

    PubMed

    Ruparelia, Neil; Colombo, Antonio; Latib, Azeem

    2016-10-01

    Redo surgery is regarded as the first-line treatment option for patients presenting with prosthetic valve degeneration. However, many patients have concomitant co-morbidities and this option is associated with significant risk. Transcatheter valve-in-valve implantation is an alternative strategy depending on the bioprosthetic valve that is being treated. The Sorin Mitroflow bioprosthetic aortic valve has been regarded as a contraindication to valve-in-valve treatment due to the high risk of coronary obstruction. We here present the case of a patient with small peripheral vasculature who underwent successful transfemoral valve-in-valve implantation and subsequently discuss the challenges and technical aspects that require consideration.

  18. Construction and characterization of a valve for rapid gas injection

    NASA Astrophysics Data System (ADS)

    Uedo, M.; Rossi, J. O.; Aso, Y.; Mangueira, L. S.; Pereira, C. A.

    1989-01-01

    An electromagnetic valve for fast gas injection was built and characterized. This type of gas injection valve is routinely applied to various plasma experiments: in magnetic confinement devices as TOKAMAK, FRP, and Compact Toroids as well as intense ion beam and neutral particle generators. The valve is capable of injecting gas pulses with up to 80 m Torr peak pressure, rising time less than 400 microsec and duration time of 40 ms, in the present experimental set-up. It is easy to build and its components can be totally acquired in the country.

  19. Development of Small-sized Fluid Control Valve with Self-holding Function Using Permanent Magnet

    NASA Astrophysics Data System (ADS)

    Akagi, Tetsuya; Dohta, Shujiro; Ueda, Hirofumi

    Recently, force feedback devices in virtual reality and power assisted nursing care systems have received much attention and active research. In such a control system, an actuator and a driving device such as a control valve are mounted on the human body. In this condition, the size and weight of the control valve become serious problems. At the same time, the valve should be operated with lower energy consumption because of using a limited electrical power. The typical electro magnetic solenoid valve drives its spool using a larger solenoid to open the valve. The complex construction of the valve for sealing makes its miniaturization and the fabrication of a low cost valve more difficult. In addition, the solenoid in the valve consumes more electrical power while the valve is kept opening. The purpose of our study is to develop a small-sized, lightweight, lower energy consumption and flexible control valve that can be safe enough to mount on the human body at a lower cost. In our pervious study, we proposed and tested the control valve that can open using a vibration motor. In this study, we propose and test a new type of fluid control valve with a self-holding function. The new valve uses a permanent magnet ball. It has a cylindrical magnet and two solenoids. The self-holding function of the valve is done as follows. When one side of the solenoid is stimulated by the current momentarily, the solenoid gives a repulsive force to the cylindrical magnet. The magnet moves toward the opposite side of the solenoid and is attracted to the iron core. Then, the magnet ball moves toward the cylindrical magnet and opens the orifice. The valve can keep open without electrical energy. As a result, the valve with the extremely lower energy consumption can be developed.

  20. Teenagers' Perceived and Actual Probabilities of Pregnancy.

    ERIC Educational Resources Information Center

    Namerow, Pearila Brickner; And Others

    1987-01-01

    Explored adolescent females' (N=425) actual and perceived probabilities of pregnancy. Subjects estimated their likelihood of becoming pregnant the last time they had intercourse, and indicated the dates of last intercourse and last menstrual period. Found that the distributions of perceived probability of pregnancy were nearly identical for both…

  1. PATIENT-SPECIFIC BICUSPID VALVE DYNAMICS: AN OVERVIEW OF METHODS AND CHALLENGES

    PubMed Central

    Chandran, Krishnan B.; Vigmostad, Sarah C.

    2012-01-01

    About 1–2% of the babies are born with bicuspid aortic valves instead of the normal aortic valve with three leaflets. A significant portion of the patients with the congenital bicuspid valve morphology suffer from aortic valve stenosis and/or ascending aortic dilatation and dissection thus requiring surgical intervention when they are young adults. Patients with bicuspid aortic valves (BAVs) have also been found to develop valvular stenosis earlier than those with the normal aortic valve. This paper overviews current knowledge of BAVs, where several studies have suggested that the mechanical stresses induced on the valve leaflets and the abnormal flow development in the ascending aorta may be an important factor in the diseases of the valve and the aortic root. The long-term goals of the studies being performed in our laboratory are aimed towards potential stratification of bicuspid valve patients who may be at risk for developing these pathologies based on analyzing the hemodynamic environment of these valves using fluid-structure interaction (FSI) modeling. Patient-specific geometry of the normal tri-cuspid and bicuspid valves are reconstructed from real-time 3D ultrasound images and the dynamic analyses performed in order to determine the potential effects of mechanical stresses on the valve leaflet and aortic root pathology. This paper describes the details of the computational tools and discusses challenges with patient-specific modeling. PMID:23182904

  2. The challenges of managing rheumatic disease of the mitral valve in Jamaica.

    PubMed

    Little, Sherard G

    2014-12-01

    Between January, 2009 and December, 2013, 84 patients were identified who underwent isolated mitral valve surgery in Jamaica at The University Hospital of the West Indies and The Bustamante Hospital for Children. The most common pathology requiring surgery was rheumatic heart disease, accounting for 84% of the procedures performed. The majority of patients had regurgitation of the mitral valve (67%), stenosis of the mitral valve (22%), and mixed mitral valve disease (11%). The most common procedure performed was replacement of the mitral valve (69%), followed by mitral valve repair (29%). Among the patients, one underwent closed mitral commissurotomy. The choice of procedure differed between age groups. In the paediatric population (<18 years of age), the majority of patients underwent repair of the mitral valve (89%). In the adult population (18 years and above), the majority of patients underwent mitral valve replacement (93%). Overall, of all the patients undergoing replacement of the mitral valve, 89% received a mechanical valve prosthesis, whereas 11% received a bioprosthetic valve prosthesis. Of the group of patients who underwent mitral valve repair for rheumatic heart disease, 19% required re-operation. The average time between initial surgery and re-operation was 1.2 years. Rheumatic fever and rheumatic heart disease remain significant public health challenges in Jamaica and other developing countries. Focus must remain on primary and secondary prevention strategies in order to limit the burden of rheumatic valvulopathies. Attention should also be directed towards improving access to surgical treatment for young adults.

  3. Realizing actual feedback control of complex network

    NASA Astrophysics Data System (ADS)

    Tu, Chengyi; Cheng, Yuhua

    2014-06-01

    In this paper, we present the concept of feedbackability and how to identify the Minimum Feedbackability Set of an arbitrary complex directed network. Furthermore, we design an estimator and a feedback controller accessing one MFS to realize actual feedback control, i.e. control the system to our desired state according to the estimated system internal state from the output of estimator. Last but not least, we perform numerical simulations of a small linear time-invariant dynamics network and a real simple food network to verify the theoretical results. The framework presented here could make an arbitrary complex directed network realize actual feedback control and deepen our understanding of complex systems.

  4. Optimal Control of the Valve Based on Traveling Wave Method in the Water Hammer Process

    NASA Astrophysics Data System (ADS)

    Cao, H. Z.; Wang, F.; Feng, J. L.; Tan, H. P.

    2011-09-01

    Valve regulation is an effective method for process control during the water hammer. The principle of d'Alembert traveling wave theory was used in this paper to construct the exact analytical solution of the water hammer, and the optimal speed law of the valve that can reduce the water hammer pressure in the maximum extent was obtained. Combining this law with the valve characteristic curve, the principle corresponding to the valve opening changing with time was obtained, which can be used to guide the process of valve closing and to reduce the water hammer pressure in the maximum extent.

  5. Rotary multiposition valve

    DOEpatents

    Barclay, John A.; Dyson, Jack E.

    1985-01-01

    The disclosure is directed to a rotary multiposition valve for selectively directing the flow of a fluid through a plurality of paths. The valve comprises an inner member and a hollow housing with a row of ducts on its outer surface. The ducts are in fluid communication with the housing. An engaging section of the inner member is received in the housing. A seal divides the engaging section into a hollow inlet segment and a hollow outlet segment. A plurality of inlet apertures are disposed in the inlet segment and a plurality of outlet apertures are disposed in the outlet segment. The inlet apertures are disposed in a longitudinally and radially spaced-apart pattern that can be a helix. The outlet apertures are disposed in a corresponding pattern. As the inner member is rotated, whenever an inlet aperture overlaps one of the ducts, the corresponding outlet aperture overlaps a different duct, thus forming a fluid pathway.

  6. Percutaneous Pulmonary Valve Implantation

    PubMed Central

    Lee, Hyoung-Doo

    2012-01-01

    Pulmonary regurgitation (PR) is a frequent sequelae after repair of tetralogy of Fallot, pulmonary atresia, truncus arteriosus, Rastelli and Ross operation. Due to patient growth and conduit degeneration, these conduits have to be changed frequently due to regurgitation or stenosis. However, morbidity is significant in these repeated operations. To prolong conduit longevity, bare-metal stenting in the right ventricular outflow tract (RVOT) obstruction has been performed. Stenting the RVOT can reduce the right ventricular pressure and symptomatic improvement, but it causes PR with detrimental effects on the right ventricle function and risks of arrhythmia. Percutaneous pulmonary valve implantation has been shown to be a safe and effective treatment for patients with pulmonary valve insufficiency, or stenotic RVOTs. PMID:23170091

  7. Cells need safety valves.

    PubMed

    Danchin, Antoine

    2009-07-01

    In Escherichia coli, the role of lacA, the third gene of the lactose operon, has remained an enigma. I suggest that its role is the consequence of the need for cells to have safety valves that protect them from the osmotic effect created by their permeases. Safety valves allow them to cope with the buildup of osmotic pressure under accidental transient conditions. Multidrug resistance (MDR) efflux, thus named because of our anthropocentrism, is ubiquitous. Yet, the formation of simple leaks would result in futile influx/efflux cycles. Versatile modification enzymes with low sensitivity solve the problem if the modified metabolite is the one exported by MDR permeases. This may account for the pervasive presence of acetyltransferases, such as LacA, associated to acetyl-metabolite exporters. This scenario of constraints imposed by efficient influx of metabolites provides us with a model that should be followed when constructing synthetic cells. PMID:19472369

  8. Rotary multiposition valve

    DOEpatents

    Barclay, J.A.; Dyson, J.E.

    1984-04-06

    The disclosure is directed to a rotary multiposition valve for selectively directing the flow of a fluid through a plurality of paths. The valve comprises an inner member and a hollow housing with a row of ducts on its outer surface. The ducts are in fluid communication with the housing. An engaging section of the inner member is received in the housing. A seal divides the engaging section into a hollow inlet segment and a hollow outlet segment. A plurality of inlet apertures are disposed in the inlet sgegment and a plurality of outlet apertures are disposed in the outlet segment. The inlet apertures are disposed in a longitudinally and radially spaced-apart pattern that can be a helix. The outlet apertures are disposed in a corresponding pattern. As the inner member is rotated, whenever an inlet aperture overlaps one of the ducts, the corresponding outlet aperture overlaps a different duct, thus forming a fluid pathway.

  9. Aspergillus prosthetic valve endocarditis.

    PubMed Central

    Petheram, I S; Seal, R M

    1976-01-01

    The clinical, laboratory, and histopathological features of seven cases of Aspergillus fumigatus prosthetic valve endocarditis are presented. The exact nature of the lesion, a combination of infective fungal endocarditis and thrombosis on the prosthetic valve, is discussed and the difficulties in clinical diagnosis are emphasized. Helpful indications were sudden unexplained heart failure with the appearance of new murmurs, and emboli to large or medium-sized systemic arteries. Fever and anaemia were inconstant, and in no case was blood culture or precipitin investigation helpful. Spore contamination of operating theatre air was the likely source of infection, and measures taken to overcome this and other predisposing factors are discussed. Since medical diagnosis is usually late and the few reported cures in this condition have included replacement of the prosthesis, early surgical intervention combined with antifungal chemotherapy is advised. Images PMID:788218

  10. Stemless ball valve

    NASA Technical Reports Server (NTRS)

    Burgess, Kevin (Inventor); Yakos, David (Inventor); Walthall, Bryan (Inventor)

    2011-01-01

    A stemless ball valve comprising two flanges and a ball with a channel, two axis pins and two travel pins. One end of each axis and travel pin is fixedly attached to the ball, and the other end of each axis pin is lodged into a notch in the first or second flange such that the axis pin is allowed to rotate in the notch. The guide sleeve comprises two channels, and one end of each travel pin is situated within one of the two channels in the guide sleeve. An outer magnetic cartridge causes the inner magnetic cartridge and guide sleeve to rotate, and when the guide sleeve rotates, the travel pins move up and down within the channels in the guide sleeve. The movement of the travel pins within the channels in the guide sleeve causes the ball to rotate, thereby opening and closing the ball valve.

  11. Fast-acting valve and uses thereof

    DOEpatents

    Meyer, James A.

    1982-01-01

    A very fast acting valve capable of producing a very well-defined plug of gas suitable for filling a theta pinch vacuum vessel is given. The valve requires no springs, instead being stopped mainly by a nonlinear force. Thus, the valve is not subject to bouncing; and the ratio of the size of the valve housing to the size of the valve stem is smaller than it would be if springs were needed to stop the valve stem. Furthermore, the valve can be used for thousands of valve firings with no apparent valve damage.

  12. Fast-acting valve and uses thereof

    DOEpatents

    Meyer, J.A.

    1980-05-16

    A very fast acting valve capable of producing a very well-defined plug of gas suitable for filling a theta pinch vacuum vessel is given. The valve requires no springs, instead being stopped mainly by a nonlinear force. Thus, the valve is not subject to bouncing; and the ratio of the size of the valve housing to the size of the valve stem is smaller than it would be if springs were needed to stop the valve stem. Furthermore, the valve can be used for thousands of valve firings with no apparent valve damage.

  13. Solenoid Valve With Self-Compensation

    NASA Technical Reports Server (NTRS)

    Woeller, Fritz H.; Matsumoto, Yutaka

    1987-01-01

    New solenoid-operated miniature shutoff valve provides self-compensation of differential pressure forces that cause jamming or insufficient valve closure as in single-seal valves. Dual-seal valve is bidirectional. Valve simultaneously seals both inlet and outlet tubes by pressing single disk of silicone rubber against ends of both.

  14. Performance Characteristics of an Isothermal Freeze Valve

    SciTech Connect

    Hailey, A.E.

    2001-08-22

    This document discusses performance characteristics of an isothermal freeze valve. A freeze valve has been specified for draining the DWPF melter at the end of its lifetime. Two freeze valve designs have been evaluated on the Small Cylindrical Melter-2 (SCM-2). In order to size the DWPF freeze valve, the basic principles governing freeze valve behavior need to be identified and understood.

  15. Controlled PCV valve

    SciTech Connect

    Zeigler, T.W. Jr.; Romanczuk, C.S.; Betterton, J.T.; Glover, A.H.

    1987-08-18

    A positive crankcase ventilation control device is described for use with an internal combustion engine and, specifically, for controlling the flow of emission laden vaporous fluids from the crankcase thereof, the control device including selective power means for substantially increasing the flow of emission laden air through the device, comprising: a generally hollow housing with an inlet forming portion adapted to be fluidly connected to the interior spaces of an internal combustion engine to receive emission laden air therefrom; the housing having an outlet forming device adapted to be fluidly connected to the air and fuel inletting portion of the internal combustion engine for disposing of the emission laden air from the engine, the inlet and outlet portions being connected within the interior of the housing by a flow control passage of specific flow area; an elongated valve plug member within the housing and having an end portion with a conically tapered configuration adapted to move progressively into the aforesaid flow control passage thereby decreasing the flow area thereof and, consequently, the total flow through the device; yieldable means urging the elongated valve member toward a position ensuring maximum flow through the flow control passage, but being yieldable to allow the valve member to move so that the conically tapered portion progressively extends further into the flow control passage to thereby decrease the flow area.

  16. The dilemma of complicated shunt valves: How to identify patients with posthemorrhagic hydrocephalus after aneurysmatic subarachnoid hemorrhage who will benefit from a simple valve?

    PubMed Central

    von der Brelie, Christian; Meier, Ullrich; Gräwe, Alexander; Lemcke, Johannes

    2016-01-01

    Background: Sophisticated shunt valves provide the possibility of pressure adjustment and antisiphon control but have a higher probability of valve dysfunction especially in a posthemorrhagic setting. The aim of the present study is to analyze the clinical outcome of patients with shunt dependent posthemorrhagic hydrocephalus after aneurysmatic subarachnoid hemorrhage (SAH) in order to identify patients who would benefit from a simple differential pressure valve. Methods: From 2000 to 2013, 547 patients with aneurysmatic SAH were treated at our institution, 114 underwent ventricular shunt placement (21.1%). 47 patients with available pre- and post-operative computed tomography scans, and an available follow-up of minimum 6 months were included. In order to measure the survival time which a nonprogrammable differential pressure valve would have had in an individual patient we defined the initial equalized shunt survival time (IESS). IESS is the time until surgical revisions of fixed differential pressure or flow-regulated valves for the treatment of over- or under-drainage as well as re-programming of adjustable valves due to over- or under-drainage. Results: Twenty patients were treated with fixed differential pressure valves, 15 patients were treated with flow-regulated valves, and 12 underwent ventriculoperitoneal (VP) shunt placement with differential pressure valves assisted by a gravitational unit. Patients who reacted with remarkable changes of the ventricular width after the insertion of external ventricular drainage (EVD), before shunt placement, showed a significantly longer IESS. Conclusions: Decline of the ventricular width after EVD placement was a predictor for successful VP shunt therapy in the later course of disease. Possibly, this could allow identifying patients who benefit from a simple differential pressure valve or a flow-regulated valve, and thus could possibly avoid valve-associated complications of a programmable valve in the later course of

  17. Intraoperative echocardiographic detection of regurgitant jets after valve replacement

    NASA Technical Reports Server (NTRS)

    Morehead, A. J.; Firstenberg, M. S.; Shiota, T.; Qin, J.; Armstrong, G.; Cosgrove, D. M. 3rd; Thomas, J. D.

    2000-01-01

    BACKGROUND: Paravalvular jets, documented by intraoperative transesophageal echocardiography, have prompted immediate valve explantation by others, yet the significance of these jets is unknown. METHODS: Twenty-seven patients had intraoperative transesophageal two-dimensional color Doppler echocardiography, performed to assess the number and area of regurgitant jets after valve replacement, before and after protamine. Patients were grouped by first time versus redo operation, valve position and type. RESULTS: Before protamine, 55 jets were identified (2.04+/-1.4 per patient) versus 29 jets after (1.07+/-1.2 per patient, p = 0.0002). Total jet area improved from 2.0+/-2.2 cm2 to 0.86+/-1.7 cm2 with protamine (p<0.0001). In all patients jet area decreased (average decrease, 70.7%+/-27.0%). First time and redo operations had similar improvements in jet number and area (both p>0.6). Furthermore, mitral and mechanical valves each had more jets and overall greater jet area when compared to aortic and tissue valves, respectively. CONCLUSIONS: Following valve replacement, multiple jets are detected by intraoperative transesophageal echocardiography. They are more common and larger in the mitral position and with mechanical valves. Improvement occurs with reversal of anticoagulation.

  18. Semi-active compressor valve

    DOEpatents

    Brun, Klaus; Gernentz, Ryan S.

    2010-07-27

    A method and system for fine-tuning the motion of suction or discharge valves associated with cylinders of a reciprocating gas compressor, such as the large compressors used for natural gas transmission. The valve's primary driving force is conventional, but the valve also uses an electromagnetic coil to sense position of the plate (or other plugging element) and to provide an opposing force prior to impact.

  19. Streamline coal slurry letdown valve

    DOEpatents

    Platt, R.J.; Shadbolt, E.A.

    1983-11-08

    A streamlined coal slurry letdown valve is featured which has a two-piece throat comprised of a seat and seat retainer. The two-piece design allows for easy assembly and disassembly of the valve. A novel cage holds the two-piece throat together during the high pressure letdown. The coal slurry letdown valve has long operating life as a result of its streamlined and erosion-resistance surfaces. 5 figs.

  20. Streamline coal slurry letdown valve

    DOEpatents

    Platt, Robert J.; Shadbolt, Edward A.

    1983-01-01

    A streamlined coal slurry letdown valve is featured which has a two-piece throat comprised of a seat and seat retainer. The two-piece design allows for easy assembly and disassembly of the valve. A novel cage holds the two-piece throat together during the high pressure letdown. The coal slurry letdown valve has long operating life as a result of its streamlined and erosion-resistance surfaces.

  1. Sequenced drive for rotary valves

    DOEpatents

    Mittell, Larry C.

    1981-01-01

    A sequenced drive for rotary valves which provides the benefits of applying rotary and linear motions to the movable sealing element of the valve. The sequenced drive provides a close approximation of linear motion while engaging or disengaging the movable element with the seat minimizing wear and damage due to scrubbing action. The rotary motion of the drive swings the movable element out of the flowpath thus eliminating obstruction to flow through the valve.

  2. The actual goals of geoethics

    NASA Astrophysics Data System (ADS)

    Nemec, Vaclav

    2014-05-01

    The most actual goals of geoethics have been formulated as results of the International Conference on Geoethics (October 2013) held at the geoethics birth-place Pribram (Czech Republic): In the sphere of education and public enlightenment an appropriate needed minimum know how of Earth sciences should be intensively promoted together with cultivating ethical way of thinking and acting for the sustainable well-being of the society. The actual activities of the Intergovernmental Panel of Climate Changes are not sustainable with the existing knowledge of the Earth sciences (as presented in the results of the 33rd and 34th International Geological Congresses). This knowledge should be incorporated into any further work of the IPCC. In the sphere of legislation in a large international co-operation following steps are needed: - to re-formulate the term of a "false alarm" and its legal consequences, - to demand very consequently the needed evaluation of existing risks, - to solve problems of rights of individuals and minorities in cases of the optimum use of mineral resources and of the optimum protection of the local population against emergency dangers and disasters; common good (well-being) must be considered as the priority when solving ethical dilemmas. The precaution principle should be applied in any decision making process. Earth scientists presenting their expert opinions are not exempted from civil, administrative or even criminal liabilities. Details must be established by national law and jurisprudence. The well known case of the L'Aquila earthquake (2009) should serve as a serious warning because of the proven misuse of geoethics for protecting top Italian seismologists responsible and sentenced for their inadequate superficial behaviour causing lot of human victims. Another recent scandal with the Himalayan fossil fraud will be also documented. A support is needed for any effort to analyze and to disclose the problems of the deformation of the contemporary

  3. Double-disc gate valve

    DOEpatents

    Wheatley, Seth J.

    1979-01-01

    This invention relates to an improvement in a conventional double-disc gate valve having a vertically movable gate assembly including a wedge, spreaders slidably engaged therewtih, a valve disc carried by the spreaders. When the gate assembly is lowered to a selected point in the valve casing, the valve discs are moved transversely outward to close inlet and outlet ports in the casing. The valve includes hold-down means for guiding the disc-and-spreader assemblies as they are moved transversely outward and inward. If such valves are operated at relatively high differential pressures, they sometimes jam during opening. Such jamming has been a problem for many years in gate valves used in gaseous diffusion plants for the separtion of uranium isotopes. The invention is based on the finding that the above-mentioned jamming results when the outlet disc tilts about its horizontal axis in a certain way during opening of the valve. In accordance with the invention, tilting of the outlet disc is maintained at a tolerable value by providing the disc with a rigid downwardly extending member and by providing the casing with a stop for limiting inward arcuate movement of the member to a preselected value during opening of the valve.

  4. Potential flow in engine valves

    NASA Technical Reports Server (NTRS)

    Eck, Bruno

    1925-01-01

    The extensive applicability of the hydrodynamic theory to the problems of engine construction is clearly shown in the following attempt to determine by exact methods the nature of the flow in valves under variously restricted conditions. Observation shows that two principal kinds of flow occur in simple flat-seated valves. For small valve lifts, the flow is along the horizontal wall and is therefore deflected 90 degrees, but for greater valve lifts the flow separates and forms a free stream, whose angle of deflection naturally increases with increasing lift. Both these kinds of flow can, in fact, be theoretically explained

  5. Mitral Valve Prolapse in Pregnancy

    PubMed Central

    Yuan, Shi-Min; Yan, Song-Li

    2016-01-01

    Mitral valve prolapse is a benign condition. Mitral regurgitation is only complicated in patients with severe mitral valve prolapse. Women with mitral valve prolapse in the absence of other cardiovascular disorders tolerate pregnancy well and do not develop remarkable cardiac complications. Nevertheless, serious complications of mitral valve prolapse, including arrhythmia, infective endocarditis and cerebral ischemic events, can be present in pregnancy. Debates remain with regard to the use of prophylactic antibiotics and β-blockers in the pregnant women with mitral valve prolapse. The prognosis of the pregnant patients might be closely related to the pathological and (or) functional changes of the mitral valve. Non-myxomatous mitral valve prolapse poses no or little obstetric risks in terms of pregnancy, labor and neonatal complications; whereas myxomatous mitral valve prolapse is a major etiology of valvular heart disease in women of childbearing age. In the pregnant patients with mitral valve prolapse progressing into major complications, surgical interventions are considered. Medicinal treatment of such patients with β-blockers should be a concern for the fetal safety. PMID:27556316

  6. Innovative Stemless Valve Eliminates Emissions

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Big Horn Valve Inc. (BHVI), of Sheridan, Wyoming, won a series of SBIR and Small Business Technology Transfer (STTR) contracts with Kennedy Space Center and Marshall Space Flight Center to explore and develop a revolutionary valve technology. BHVI developed a low-mass, high-efficiency, leak-proof cryogenic valve using composites and exotic metals, and had no stem-actuator, few moving parts, with an overall cylindrical shape. The valve has been installed at a methane coal gas field, and future applications are expected to include in-flight refueling of military aircraft, high-volume gas delivery systems, petroleum refining, and in the nuclear industry.

  7. Latest design of gate valves

    SciTech Connect

    Kurzhofer, U.; Stolte, J.; Weyand, M.

    1996-12-01

    Babcock Sempell, one of the most important valve manufacturers in Europe, has delivered valves for the nuclear power industry since the beginning of the peaceful application of nuclear power in the 1960s. The latest innovation by Babcock Sempell is a gate valve that meets all recent technical requirements of the nuclear power technology. At the moment in the United States, Germany, Sweden, and many other countries, motor-operated gate and globe valves are judged very critically. Besides the absolute control of the so-called {open_quotes}trip failure,{close_quotes} the integrity of all valve parts submitted to operational forces must be maintained. In case of failure of the limit and torque switches, all valve designs have been tested with respect to the quality of guidance of the gate. The guidances (i.e., guides) shall avoid a tilting of the gate during the closing procedure. The gate valve newly designed by Babcock Sempell fulfills all these characteristic criteria. In addition, the valve has cobalt-free seat hardfacing, the suitability of which has been proven by friction tests as well as full-scale blowdown tests at the GAP of Siemens in Karlstein, West Germany. Babcock Sempell was to deliver more than 30 gate valves of this type for 5 Swedish nuclear power stations by autumn 1995. In the presentation, the author will report on the testing performed, qualifications, and sizing criteria which led to the new technical design.

  8. Valve-in-Valve-in-Valve Transcatheter Aortic Valve Implantation to Treat a Degenerated Surgical Bioprosthesis in a Subaortic Position

    PubMed Central

    Nuis, Rutger-Jan; Benitez, Luis M.; Nader, Carlos A.; Perez, Sergio; de Marchena, Eduardo J.; Dager, Antonio E.

    2013-01-01

    Transcatheter aortic valve implantation for aortic stenosis has evolved as an alternative treatment for patients who are at high or excessive surgical risk. We report the case of an 84-year-old man with a degenerated surgically implanted valve in a subaortic position (9 mm below the native annulus) who underwent “valve-in-valve” transcatheter aortic valve implantation with use of a Medtronic CoreValve system. We planned to deploy the CoreValve at a conventional depth in the left ventricular outflow tract; we realized that this might result in paravalvular regurgitation, but it would also afford a “deep” landing site for a second valve, if necessary. Ultimately, we implanted a second CoreValve deep in the left ventricular outflow tract to seal a paravalvular leak. The frame of the first valve—positioned at the conventional depth—enabled secure anchoring of the second valve in a deeper position, which in turn effected successful treatment of the failing subaortic surgical prosthesis without paravalvular regurgitation. PMID:23914032

  9. Almanac 2014: aortic valve disease.

    PubMed

    Otto, Catherine M

    2015-06-01

    The past few years have seen major advances in the diagnosis of aortic valve disease and in our understanding of the pathophysiology of disease. In addition, transcatheter aortic valve implantation has transformed our clinical management options. This article summarises new aortic valve disease research published in Heart in 2013 and 2014, within the context of other major studies published in general medical journals, including a discussion of the potential impact of these new research findings on the clinical approach to management of adults with aortic valve disease.

  10. Prosthetic valve endocarditis: an overview.

    PubMed

    Gnann, J W; Dismukes, W E

    1983-12-01

    Infection of an intracardiac prosthesis, the incidence of which is about 2.5% among patients having undergone valve replacement, is a serious complication with considerable morbidity and mortality. Early prosthetic valve endocarditis (PVE), with an onset within 60 days of valve replacement, accounts for approximately one-third of all cases, while the remaining two-thirds, occur more than two months postoperatively (late prosthetic valve endocarditis). Prosthetic valve endocarditis is most commonly caused by Staphylococcus epidermidis, less frequently by viridans streptococci, Staphylococcus aureus, and gram-negative bacilli. The most likely pathogenetic mechanisms in prosthetic valve endocarditis are intraoperative contamination and postoperative infections at extracardiac sites. Prominent clinical features include fever, new or changing heart murmurs, leukocytosis, anemia and hematuria. The etiologic microorganism can be isolated in more than 90% of all cases. Patients with proven prosthetic valve endocarditis should be examined daily to detect signs of congestive heart failure and changes in murmurs; electrocardiographic monitoring is essential for documentation of arrhythmias. With limitations, echocardiography, especially two-dimensional, may help to demonstrate vegetations or valvular dehiscence. Cinefluoroscopy may reveal loosening or dehiscence of the sewing ring or impaired motion of a radio-opaque poppet due to thrombus or vegetation. Cardiac catheterization, not always necessary even when surgical intervention is anticipated, may provide valuable information on the degree of dysfunction, multiple valve involvement, left ventricular function and extent of concomitant coronary artery disease. In patients with mechanical valves, prosthetic valve endocarditis may be associated with a high incidence of valve ring and myocardial abscesses; the reported frequency of valve ring abscesses is lower with porcine heterografts. Infections on mechanical valves

  11. Dynamic performance of high speed solenoid valve with parallel coils

    NASA Astrophysics Data System (ADS)

    Kong, Xiaowu; Li, Shizhen

    2014-07-01

    The methods of improving the dynamic performance of high speed on/off solenoid valve include increasing the magnetic force of armature and the slew rate of coil current, decreasing the mass and stroke of moving parts. The increase of magnetic force usually leads to the decrease of current slew rate, which could increase the delay time of the dynamic response of solenoid valve. Using a high voltage to drive coil can solve this contradiction, but a high driving voltage can also lead to more cost and a decrease of safety and reliability. In this paper, a new scheme of parallel coils is investigated, in which the single coil of solenoid is replaced by parallel coils with same ampere turns. Based on the mathematic model of high speed solenoid valve, the theoretical formula for the delay time of solenoid valve is deduced. Both the theoretical analysis and the dynamic simulation show that the effect of dividing a single coil into N parallel sub-coils is close to that of driving the single coil with N times of the original driving voltage as far as the delay time of solenoid valve is concerned. A specific test bench is designed to measure the dynamic performance of high speed on/off solenoid valve. The experimental results also prove that both the delay time and switching time of the solenoid valves can be decreased greatly by adopting the parallel coil scheme. This research presents a simple and practical method to improve the dynamic performance of high speed on/off solenoid valve.

  12. Low energy high pressure miniature screw valve

    DOEpatents

    Fischer, Gary J.; Spletzer, Barry L.

    2006-12-12

    A low energy high pressure screw valve having a valve body having an upper portion and a lower portion, said lower portion of said valve body defining an inlet flow passage and an outlet flow passage traversing said valve body to a valve seat, said upper portion of said valve body defining a cavity at said valve seat, a diaphragm restricting flow between said upper portion of said valve body and said lower portion, said diaphragm capable of engaging said valve seat to restrict fluid communication between said inlet passage and said outlet passage, a plunger within said cavity supporting said diaphragm, said plunger being capable of engaging said diaphragm with said valve seat at said inlet and outlet fluid passages, said plunger being in point contact with a drive screw having threads engaged with opposing threads within said upper portion of said valve body such engagement allowing motion of said drive screw within said valve body.

  13. All metal valve structure for gas systems

    DOEpatents

    Baker, Ray W.; Pawlak, Donald A.; Ramey, Alford J.

    1984-11-13

    A valve assembly with a resilient metal seat member is disclosed for providing a gas-tight seal in a gas handling system. The valve assembly also includes a valve element for sealing against the valve seat member; and an actuating means for operating the valve element. The valve seat member is a one-piece stainless steel ring having a central valve port and peripheral mounting flange, and an annular corrugation in between. A groove between the first and second ridges serves as a flexure zone during operation of the valve member and thus provides the seating pressure between the inner ridge or valve seat and the valve element. The outer annular ridge has a diameter less than said valve element to limit the seating motion of the valve element, preventing non-elastic deformation of the seat member.

  14. Congenital quadricuspid aortic valve associated with aortic insufficiency and mitral regurgitation

    PubMed Central

    2013-01-01

    Congenital quadricuspid aortic valve is a rare cardiac anomaly. More than half of the patients with this abnormality will develop aortic insufficiency in adulthood. It is vital that patients with quadricuspid aortic valve who present with progressive aortic regurgitation undergo valve replacement or repair at appropriate time. Here, we present two cases of quadricuspid aortic valve. We first describe a 58-year-old man who had mitral regurgitation and ascending aorta dilatation with quadricuspid aortic valve. He underwent aortic valve replacement and mitral valve plasty and recovered well. The second patient is a 20-year-old asymptomatic boy who has been closely followed up and has not received any surgical treatment. PMID:23587156

  15. Congenital quadricuspid aortic valve associated with aortic insufficiency and mitral regurgitation.

    PubMed

    Zhu, Jiaquan; Zhang, Junwen; Wu, Shubin; Zhang, Yunjiao; Ding, Fangbao; Mei, Ju

    2013-01-01

    Congenital quadricuspid aortic valve is a rare cardiac anomaly. More than half of the patients with this abnormality will develop aortic insufficiency in adulthood. It is vital that patients with quadricuspid aortic valve who present with progressive aortic regurgitation undergo valve replacement or repair at appropriate time. Here, we present two cases of quadricuspid aortic valve. We first describe a 58-year-old man who had mitral regurgitation and ascending aorta dilatation with quadricuspid aortic valve. He underwent aortic valve replacement and mitral valve plasty and recovered well. The second patient is a 20-year-old asymptomatic boy who has been closely followed up and has not received any surgical treatment. PMID:23587156

  16. Designing of the massive gas injection valve for the joint Texas experimental tokamak

    NASA Astrophysics Data System (ADS)

    Luo, Y. H.; Chen, Z. Y.; Tang, Y.; Wang, S. Y.; Ba, W. G.; Wei, Y. N.; Ma, T. K.; Huang, D. W.; Tong, R. H.; Yan, W.; Geng, P.; Shao, J.; Zhuang, G.

    2014-08-01

    In order to mitigate the negative effects of the plasma disruption a massive gas injection (MGI) valve is designed for the joint Texas experimental tokamak. The MGI valve is based on the eddy-current repulsion mechanism. It has a fueling volume of 30 ml. The piston of the MGI valve is made by non-ferromagnetic material, so it can be installed close to the vacuum vessel which has a strong toroidal magnetic field. A diode is use to prevent current oscillation in the discharge circuit. The drive coil of the valve is installed outside the gas chamber. The opening characteristics and the gas flow of the MGI valve have been tested by a 60 l vacuum chamber. Owing to the large electromagnetic force the reaction time of the valve is shorter than 0.3 ms. Duration for the opening of the MGI valve is in the order of 10 ms.

  17. DISCHARGE VALVE FOR GRANULAR MATERIAL

    DOEpatents

    Stoughton, L.D.; Robinson, S.T.

    1962-05-15

    A gravity-red dispenser or valve is designed for discharging the fueled spherical elements used in a pebble bed reactor. The dispenser consists of an axially movable tube terminating under a hood having side walls with openings. When the tube is moved so that its top edge is above the tops of the side openings the elements will not flow. As the tube is moved downwardly, the elements flow into the hood through the side openings and over the top edge into the tube at an increasing rate as the tube is lowered further. The tube is spaced at all times from the hood and side walls a distance greater than the diameter of the largest element to prevent damaging of the elements when the dispenser is closed to flow. (AEC)

  18. Linguistic Theory and Actual Language.

    ERIC Educational Resources Information Center

    Segerdahl, Par

    1995-01-01

    Examines Noam Chomsky's (1957) discussion of "grammaticalness" and the role of linguistics in the "correct" way of speaking and writing. It is argued that the concern of linguistics with the tools of grammar has resulted in confusion, with the tools becoming mixed up with the actual language, thereby becoming the central element in a metaphysical…

  19. El Observatorio Gemini - Status actual

    NASA Astrophysics Data System (ADS)

    Levato, H.

    Se hace una breve descripción de la situación actual del Observatorio Gemini y de las últimas decisiones del Board para incrementar la eficiencia operativa. Se hace también una breve referencia al uso argentino del observatorio.

  20. Effects of bileaflet mechanical heart valve orientation on coronary flow

    NASA Astrophysics Data System (ADS)

    Haya, Laura; Tavoularis, Stavros

    2015-11-01

    The aortic sinus is approximately tri-radially symmetric, but bileaflet mechanical heart valves (BMHVs), which are commonly used to replace diseased aortic valves, are bilaterally symmetric. This mismatch in symmetry suggests that the orientation in which a BMHV is implanted within the aortic sinus affects the flow characteristics downstream of it. This study examines the effect of BMHV orientation on the flow in the coronary arteries, which originate in the aortic sinus and supply the heart tissue with blood. Planar particle image velocimetry measurements were made past a BMHV mounted at the inlet of an anatomical aorta model under physiological flow conditions. The complex interactions between the valve jets, the sinus vortex and the flow in the right coronary artery were elucidated for three valve orientations. The coronary flow rate was directly affected by the size, orientation, and time evolution of the vortex in the sinus, all of which were sensitive to the valve's orientation. The total flow through the artery was highest when the valve was oriented with its axis of symmetry intersecting the artery's opening. The findings of this research may assist surgeons in choosing the best orientation for BMHV implantation. The bileaflet valve was donated by St. Jude Medical. Financial support was provided by the Natural Sciences and Engineering Research Council of Canada.

  1. Prognostics for Ground Support Systems: Case Study on Pneumatic Valves

    NASA Technical Reports Server (NTRS)

    Daigle, Matthew; Goebel, Kai

    2011-01-01

    Prognostics technologies determine the health (or damage) state of a component or sub-system, and make end of life (EOL) and remaining useful life (RUL) predictions. Such information enables system operators to make informed maintenance decisions and streamline operational and mission-level activities. We develop a model-based prognostics methodology for pneumatic valves used in ground support equipment for cryogenic propellant loading operations. These valves are used to control the flow of propellant, so failures may have a significant impact on launch availability. Therefore, correctly predicting when valves will fail enables timely maintenance that avoids launch delays and aborts. The approach utilizes mathematical models describing the underlying physics of valve degradation, and, employing the particle filtering algorithm for joint state-parameter estimation, determines the health state of the valve and the rate of damage progression, from which EOL and RUL predictions are made. We develop a prototype user interface for valve prognostics, and demonstrate the prognostics approach using historical pneumatic valve data from the Space Shuttle refueling system.

  2. PMMA/PDMS valves and pumps for disposable microfluidics.

    PubMed

    Zhang, Wenhua; Lin, Shuichao; Wang, Chunming; Hu, Jia; Li, Cong; Zhuang, Zhixia; Zhou, Yongliang; Mathies, Richard A; Yang, Chaoyong James

    2009-11-01

    Poly(methyl methacrylate) (PMMA) is gaining in popularity in microfluidic devices because of its low cost, excellent optical transparency, attractive mechanical/chemical properties, and simple fabrication procedures. It has been used to fabricate micromixers, PCR reactors, CE and many other microdevices. Here we present the design, fabrication, characterization and application of pneumatic microvalves and micropumps based on PMMA. Valves and pumps are fabricated by sandwiching a PDMS membrane between PMMA fluidic channel and manifold wafers. Valve closing or opening can be controlled by adjusting the pressure in a displacement chamber on the pneumatic layer via a computer regulated solenoid. The valve provides up to 15.4 microL s(-1) at 60 kPa fluid pressure and seals reliably against forward fluid pressure as high as 60 kPa. A PMMA diaphragm pump can be assembled by simply connecting three valves in series. By varying valve volume or opening time, pumping rates ranging from nL to microL per second can be accurately achieved. The PMMA based valves and pumps were further tested in a disposable automatic nucleic acid extraction microchip to extract DNA from human whole blood. The DNA extraction efficiency was about 25% and the 260 nm/280 nm UV absorption ratio for extracted DNA was 1.72. Because of its advantages of inexpensive, facile fabrication, robust and easy integration, the PMMA valve and pump will find their wide application for fluidic manipulation in portable and disposable microfluidic devices.

  3. 241-AN-A valve pit manifold valves and position indication acceptance test procedure

    SciTech Connect

    VANDYKE, D.W.

    1999-08-25

    This document describes the method used to test design criteria for gear actuated ball valves installed in 241-AN-A Valve Pit located at 200E Tank Farms. The purpose of this procedure is to demonstrate the following: Equipment is properly installed, labeled, and documented on As-Built drawings; New Manifold Valves in the 241-AN-A Valve Pit are fully operable using the handwheel of the valve operators; New valve position indicators on the valve operators will show correct valve positions; New valve position switches will function properly; and New valve locking devices function properly.

  4. 241-AN-B valve pit manifold valves and position indication acceptance test procedure

    SciTech Connect

    VANDYKE, D.W.

    1999-08-25

    This document describes the method used to test design criteria for gear actuated ball valves installed in 241-AN-B Valve Pit located at 200E Tank Farms. The purpose of this procedure is to demonstrate the following: Equipment is properly installed, labeled, and documented on As-Built drawings; New Manifold Valves in the 241-AN-B Valve Pit are fully operable using the handwheel of the valve operators; New valve position indicators on the valve operators will show correct valve positions; New valve position switches will function properly; and New valve locking devices function properly.

  5. Transcatheter Valve-in-Valve: A Cautionary Tale.

    PubMed

    Luc, Jessica G Y; Shanks, Miriam; Tyrrell, Benjamin D; Welsh, Robert C; Butler, Craig R; Meyer, Steven R

    2016-09-01

    Transcatheter aortic valve replacement (TAVR) by valve-in-valve (VIV) implantation is an alternative treatment for high-risk patients with a degenerating aortic bioprosthesis. We present a case of transapical TAVR VIV with a 29-mm Edwards SAPIEN XT (ESV) (Edwards Lifesciences, Irvine, CA) into a 29-mm Medtronic Freestyle stentless bioprosthesis (Medtronic Inc, Minneapolis, MN) in which unanticipated dilatation of the Freestyle bioprosthesis resulted in intraprocedural embolization of the TAVR valve, necessitating urgent conversion to a conventional surgical aortic valve replacement (AVR). Our experience suggests that TAVR VIV with the 29-mm ESV in the setting of a degenerated 29-mm Freestyle stentless bioprosthesis must be undertaken with caution. PMID:27549545

  6. Variable reluctance proximity sensors for cryogenic valve position indication

    NASA Technical Reports Server (NTRS)

    Cloyd, R. A.

    1982-01-01

    A test was conducted to determine the performance of a variable reluctance proximity sensor system when installed in a space shuttle external tank vent/relief valve. The sensors were used as position indicators. The valve and sensors were cycled through a series of thermal transients; while the valve was being opened and closed pneumatically, the sensor's performance was being monitored. During these thermal transients, the vent valve was cooled ten times by liquid nitrogen and two times by liquid hydrogen. It was concluded that the sensors were acceptable replacements for the existing mechanical switches. However, the sensors need a mechanical override for the target similar to what is presently used with the mechanical switches. This override could insure contact between sensor and target and eliminate any problems of actuation gap growth caused by thermal gradients.

  7. Evaluation of the Melody transcatheter pulmonary valve and Ensemble delivery system for the treatment of dysfunctional right ventricle to pulmonary artery conduits.

    PubMed

    Asnes, Jeremy; Hellenbrand, William E

    2015-01-01

    Synthetic conduits and bioprosthetic valves are used in the treatment of patients with congenital heart disease involving the right ventricular outflow tract and pulmonary valve. In-situ time-dependent degradation uniformly results in conduit and valve dysfunction. The abnormal hemodynamics imposed by valve and conduit dysfunction have been linked to exercise intolerance, arrhythmia, right heart failure, and sudden death. Starting in childhood, affected patients are subjected to repeated open-heart surgeries to restore valve function and potentially reduce morbidity and mortality. Percutaneous transcatheter pulmonary valve replacement with the Melody Transcatheter Pulmonary Valve (Medtronic, Inc., Minneapolis, MN) has been performed in ≈8000 patients worldwide. The valve and implant procedure provide a far less invasive means of restoring valve and conduit function and allow patients to forego multiple operations. Recent clinical trials have shown excellent and durable results in terms of valve function, relief of obstruction, and improvement in functional class up to 7 years from implant. PMID:26513599

  8. Blood conservation strategies in cardiac valve replacement

    PubMed Central

    Zheng, Junnan; Chen, Liangwei; Qian, Linfeng; Jiang, Jianjie; Chen, Yinglian; Xie, Jue; Shi, Liping; Ni, Yiming; Zhao, Haige

    2016-01-01

    Abstract We aimed to evaluate whether blood conservation strategies including intraoperative autologous donation (IAD) could reduce perioperative blood transfusion for patients undergoing cardiac valve replacement including mitral valve replacement, aortic valve replacement (AVR), and double valve replacement (DVR). A total of 726 patients were studied over a 3-year period (2011–2013) after the implementation of IAD and were compared with 919 patients during the previous 36-month period (January 2008–December 2010). The method of small-volume retrograde autologous priming, strict blood transfusion standard together with IAD constituted a progressive blood-saving strategy. Baseline characteristics and preoperative information showed no statistically significant difference between IAD group and non-IAD group. Most of the postoperative morbidities are statistically the same in the 2 groups. Chest tube output (415.2 vs 1029.8 mL, P < 0.001) and postoperative respiratory failure (5.9% vs 8.6%, P = 0.039) favored the IAD group, whereas hematocrit levels were more favorable in the non-IAD group (30.3% vs 33.0% at the end of the operation, P < 0.001; 30.4% vs 31.5% at the time of discharge). The use of blood product transfusion was higher in the non-IAD group (22.6% vs 43.3%, P < 0.001). Binary multivariate logistic regression analysis showed that high age, non-IAD, DVR surgery, and absent smoking history are associated with a higher risk of intra-/postoperative blood transfusion. Blood conservation is effective and safe in cardiac valve replacement surgeries. The use of intraoperative autologous donation can lead to improved outcomes including a significantly lower rate of intra-/postoperative blood transfusion and postoperative complications. PMID:27741149

  9. Bioprosthetic heart valve leaflet motion under simulated physiologic conditions

    NASA Astrophysics Data System (ADS)

    Zhi, Gao

    The application of current bioprosthetic heart valves is limited by the lack of valve durability. Valve failure is thought to be related to uneven stress distribution within the leaflet, which is associated with subtle aspects of leaflet motion, such as excessive bending and wrinkling, during valve opening and closing in a cardiac cycle. However, detailed descriptions of the valve motion, particularly leaflet deformation, are not available in the literature. To address this problem, new metrological methodology, based on optical imaging techniques, was developed to assess the leaflet motion of bioprosthetic heart valves under simulated physiologic conditions. To investigate the realistic leaflet motion, which is strongly linked to the fluid flow through the valve, a new hydrodynamic testing loop was built from modifications of an existing design. While the new loop retained the main characteristics of the old loop, which closely simulates physiologic conditions, the design of an optical window permitted visualization of the valve leaflet in dynamic motion. These sequences of leaflet motion obtained under such accurately simulated physiological waveforms, as depicted in this dissertation, have never been previously reported. By designing a unique triggering mechanism, dual-camera stereo photogrammetry was developed. Instead of using stereo photogrammetry to investigate static or quasi- static valve leaflet surface contours, dynamic sequences of the leaflet motion in a complete valve opening and closing cycle were retrieved. In addition, introduction of the double-pulse illumination technique took advantage of the field transfer mechanism of the CCD camera and captured two consecutive images within a short time. A sequence of leaflet deformation diagrams from this technique was reconstructed for the first time. Also, structured light photogrammetry, using the Fourier transform fringe analysis method, was developed. It featured nondestructive surface contour

  10. Combination throttle and shutoff valve

    NASA Technical Reports Server (NTRS)

    Carriker, J. W.

    1972-01-01

    Combination of translating sleeve throttle valve and conventional poppet valve provides capability of shutting off flow completely by poppet and sleeve control of the rate of flow. Integration of the two concepts can be accomplished without difficulty and in a manner that requires a minimum of development.

  11. Surge-damping vacuum valve

    DOEpatents

    Bullock, Jack C.; Kelly, Benjamin E.

    1980-01-01

    A valve having a mechanism for damping out flow surges in a vacuum system which utilizes a slotted spring-loaded disk positioned adjacent the valve's vacuum port. Under flow surge conditions, the differential pressure forces the disk into sealing engagement with the vacuum port, thereby restricting the flow path to the slots in the disk damping out the flow surge.

  12. Air flow through poppet valves

    NASA Technical Reports Server (NTRS)

    Lewis, G W; Nutting, E M

    1920-01-01

    Report discusses the comparative continuous flow characteristics of single and double poppet valves. The experimental data presented affords a direct comparison of valves, single and in pairs of different sizes, tested in a cylinder designed in accordance with current practice in aviation engines.

  13. Awake transapical aortic valve implantation.

    PubMed

    Petridis, Francesco Dimitri; Savini, Carlo; Castelli, Andrea; Di Bartolomeo, Roberto

    2012-05-01

    Transapical aortic valve implantation is being employed as a less invasive alternative to open heart surgery in high-risk patients with severe aortic stenosis. Here we report the case of an awake transapical aortic valve implantation in a patient with severe chronic obstructive pulmonary disease.

  14. Variable gas leak rate valve

    DOEpatents

    Eernisse, Errol P.; Peterson, Gary D.

    1976-01-01

    A variable gas leak rate valve which utilizes a poled piezoelectric element to control opening and closing of the valve. The gas flow may be around a cylindrical rod with a tubular piezoelectric member encircling the rod for seating thereagainst to block passage of gas and for reopening thereof upon application of suitable electrical fields.

  15. High pressure gate valve failure

    SciTech Connect

    Place, M. Jr.; Kochera, J.W.

    1995-10-01

    Shell Oil Company was attempting to develop CRA (Corrosion Resistant Alloy) valves for use in those completions utilizing CRA tubing. The testing and development of new materials for CRA valves of both the solid and clad version were pursued. As part of this CRA valve development program, Shell Oil Company tried to reconcile the apparent discrepancy between unacceptable laboratory test results on 410 SS in sour environments with both the apparent success (when properly heat treated and at an acceptable hardness level) of this alloy in commercial sour use and the fact that it is fully accepted in NACE MR-01-75. A410 stainless steel valve was tested near the material yield strength at low H{sub 2}S partial pressures at the STF (Static Test Facility) in Mississippi. The valve failed by crack growth and body wall leakage while under test.

  16. Automatic monitoring of valve status

    SciTech Connect

    Prinz, F.B.; Chern, J.H.

    1988-01-01

    Authors note that acoustic emissions from valves and adjacent pipe, used to investigate the problem of valve leakage in power plants, cannot be separated so as to distinguish leakage processes from other causes of ultrasound emissions. They propose establishing the relationship between valve leaking and thermal gradient to allow detection of valve leakage by observing the piping system`s temperature profile. Authors note that their mathematical and experimental models of a typical power-plant piping section were found inconsistent, report known and suspected reasons for this, and suggest specific further studies to supply missing data. They also suggest designing modern power plants to accommodate a remotely controlled or autonomous vehicle which would carry a device for thermal-gradient leak detection to examine valves in situ.

  17. Packing developments improve valve availability

    SciTech Connect

    Aikin, J.

    1994-01-01

    Regulatory environment and clean air legislation demand improvements in valve stuffing box performance. In normally inaccessible or hazardous areas, the cost of valve maintenance and repair in terms of safety, radiation, and toxic gas exposure is very high. AECL Research`s Mechanical Equipment Development (MED) branch at Chalk River Laboratories (Chalk River, Ont.) has researched stem packing leakage problems since the early 1970s. Early research and development (R and D) significantly improved the understanding of operational characteristics of asbestos-based valve packing. Of note was the development of live loading, a stem packing method that reduces valve leakage to near zero under most operating conditions, and significantly prolongs packing life. This article describes how stem packing developments, including live loading techniques, are reducing valve fugitive emissions and leakage.

  18. Mitral Valve Annuloplasty

    PubMed Central

    Rausch, Manuel K.; Bothe, Wolfgang; Kvitting, John-Peder Escobar; Swanson, Julia C.; Miller, D. Craig; Kuhl, Ellen

    2012-01-01

    Mitral valve annuloplasty is a common surgical technique used in the repair of a leaking valve by implanting an annuloplasty device. To enhance repair durability, these devices are designed to increase leaflet coaptation, while preserving the native annular shape and motion; however, the precise impact of device implantation on annular deformation, strain, and curvature is unknown. Here we quantify how three frequently used devices significantly impair native annular dynamics. In controlled in vivo experiments, we surgically implanted eleven flexible-incomplete, eleven semi-rigid-complete, and twelve rigid-complete devices around the mitral annuli of 34 sheep, each tagged with 16 equally-spaced tantalum markers. We recorded four-dimensional marker coordinates using biplane videofluoroscopy, first with device and then without, which were used to create mathematical models using piecewise cubic splines. Clinical metrics (characteristic anatomical distances) revealed significant global reduction in annular dynamics upon device implantation. Mechanical metrics (strain and curvature fields) explained this reduction via a local loss of anterior dilation and posterior contraction. Overall, all three devices unfavorably reduced annular dynamics. The flexible-incomplete device, however, preserved native annular dynamics to a larger extent than the complete devices. Heterogeneous strain and curvature profiles suggest the need for heterogeneous support, which may spawn more rational design of annuloplasty devices using design concepts of functionally graded materials. PMID:22037916

  19. Hydraulic valve lifter

    SciTech Connect

    Kodama, H.; Ono, T.

    1986-11-25

    This patent describes a hydraulic valve lifter mounted in a rocker arm of a valve train assembly of internal combustion engines, the lifter comprising: a cylinder having a cylindrical surface formed in the rocker arm; a plunger reciprocally mounted in the cylinder in sliding contact with the cylindrical surface; a seat member securely pressed in the cylinder above the plunger. The seat member defines a reservoir chamber and a pressure chamber in the cylinder and having an outer circumferential portion extending in contact with the cylindrical surface in a direction of the plunger; a stopper means formed at an end surface of the outer circumferential portion of the seat member for restricting an axial movement of the plunger in a direction of the seat member; and at least one relief means formed in the cylindrical surface above the stopper means for a finishing machining process of the cylinder whereby each recess means is completely covered by the outer circumferential portion of the seat member. In this way, the cylindrical surface encircles the plunger and is formed by an uninterrupted smooth sliding surface along the entire length of movement of the plunger.

  20. Determinants of valve gating in collecting lymphatic vessels from rat mesentery.

    PubMed

    Davis, Michael J; Rahbar, Elaheh; Gashev, Anatoliy A; Zawieja, David C; Moore, James E

    2011-07-01

    Secondary lymphatic valves are essential for minimizing backflow of lymph and are presumed to gate passively according to the instantaneous trans-valve pressure gradient. We hypothesized that valve gating is also modulated by vessel distention, which could alter leaflet stiffness and coaptation. To test this hypothesis, we devised protocols to measure the small pressure gradients required to open or close lymphatic valves and determine if the gradients varied as a function of vessel diameter. Lymphatic vessels were isolated from rat mesentery, cannulated, and pressurized using a servo-control system. Detection of valve leaflet position simultaneously with diameter and intraluminal pressure changes in two-valve segments revealed the detailed temporal relationships between these parameters during the lymphatic contraction cycle. The timing of valve movements was similar to that of cardiac valves, but only when lymphatic vessel afterload was elevated. The pressure gradients required to open or close a valve were determined in one-valve segments during slow, ramp-wise pressure elevation, either from the input or output side of the valve. Tests were conducted over a wide range of baseline pressures (and thus diameters) in passive vessels as well as in vessels with two levels of imposed tone. Surprisingly, the pressure gradient required for valve closure varied >20-fold (0.1-2.2 cmH(2)O) as a passive vessel progressively distended. Similarly, the pressure gradient required for valve opening varied sixfold with vessel distention. Finally, our functional evidence supports the concept that lymphatic muscle tone exerts an indirect effect on valve gating.

  1. Patents and heart valve surgery - II: tissue valves.

    PubMed

    Cheema, Faisal H; Kossar, Alexander P; Rehman, Atiq; Younas, Fahad; Polvani, Gianluca

    2013-08-01

    Valvular heart disease affects millions of Americans yearly and currently requires surgical intervention to repair or replace the defective valves. Through a close-knit collaboration between physicians, scientists and biomedical engineers, a vast degree of research and development has been aimed towards the optimization of prosthetic heart valves. Although various methods have made fantastic strides in producing durable prostheses, the therapeutic efficacy of prosthetic valves is inherently limited by a dependency upon lifelong anticoagulant regimens for recipients - a difficult challenge for many in clinical setting. Thus, biological tissue valves have been developed to circumvent vascular and immunemediated complications by incorporating biological materials to mimic native valves while still maintaining a necessary level of structural integrity. Over the past decade, a multitude of patents pertaining to the refinement of designs as well as the advancement in methodologies and technologies associated with biological tissue valves have been issued. This review seeks to chronicle and characterize such patents in an effort to track the past, present, and future progress as well as project the trajectory of tissue valves in the years to come.

  2. Valve-related complications after mechanical heart valve implantation.

    PubMed

    Misawa, Yoshio

    2015-10-01

    The number of heart valve surgeries is increasing, and 19,164 patients underwent heart valve surgery in Japan in 2011. The early mortality rate has remained stable for more than 10 years. Many patients now survive for many years, with a reported 10-year survival rate of at least 60 %. However, unfavorable complications can occur after valve surgery. Valve-related complications include thromboembolisms, bleeding complications and prosthetic valve endocarditis, followed by structural and nonstructural prosthetic valve dysfunctions. Our review of studies published after 2000 revealed that the rate of all valve-related complications was 0.7-3.5 % per patient-year. Thromboembolisms occur at a rate of approximately 1 % per patient-year, and bleeding complications occur at almost 0.5 % per patient-year. Thromboembolic and hemorrhagic events related to anticoagulant therapy should be considered during life-long follow-up. The occurrence rate of endocarditis reaches 0.5 % per patient-year, with a poor postoperative survival. Structural dysfunctions have been largely overcome, and the nonstructural dysfunction rate is 0.4-1.2 % per patient-year. The nonstructural dysfunctions induced by paravalvular leaks and pannus ingrowth are also issues that need to be resolved.

  3. Self-Rupturing Hermetic Valve

    NASA Technical Reports Server (NTRS)

    Tucker, Curtis E., Jr.; Sherrit, Stewart

    2011-01-01

    For commercial, military, and aerospace applications, low-cost, small, reliable, and lightweight gas and liquid hermetically sealed valves with post initiation on/off capability are highly desirable for pressurized systems. Applications include remote fire suppression, single-use system-pressurization systems, spacecraft propellant systems, and in situ instruments. Current pyrotechnic- activated rupture disk hermetic valves were designed for physically larger systems and are heavy and integrate poorly with portable equipment, aircraft, and small spacecraft and instrument systems. Additionally, current pyrotechnically activated systems impart high g-force shock loads to surrounding components and structures, which increase the risk of damage and can require additional mitigation. The disclosed mechanism addresses the need for producing a hermetically sealed micro-isolation valve for low and high pressure for commercial, aerospace, and spacecraft applications. High-precision electrical discharge machining (EDM) parts allow for the machining of mated parts with gaps less than a thousandth of an inch. These high-precision parts are used to support against pressure and extrusion, a thin hermetically welded diaphragm. This diaphragm ruptures from a pressure differential when the support is removed and/or when the plunger is forced against the diaphragm. With the addition of conventional seals to the plunger and a two-way actuator, a derivative of this design would allow nonhermetic use as an on/off or metering valve after the initial rupturing of the hermetic sealing disk. In addition, in a single-use hermetically sealed isolation valve, the valve can be activated without the use of potential leak-inducing valve body penetrations. One implementation of this technology is a high-pressure, high-flow-rate rupture valve that is self-rupturing, which is advantageous for high-pressure applications such as gas isolation valves. Once initiated, this technology is self

  4. Giant Thoracic Aneurysm Following Valve Replacement for Bicuspid Aortic Valve.

    PubMed

    Tran, Cao; Ul Haq, Ehtesham; Nguyen, Ngoc; Omar, Bassam

    2015-01-01

    Bicuspid aortic valve is a common congenital anomaly associated with aortopathy, which can cause aortic root dilatation, necessitating regular screening if the aortic root is > 4.0 cm. Despite the low absolute incidence of aortic complications associated with bicuspid aortic valve in the general population, the consequences of such complications for an individual patient can be devastating. Herein we propose a balanced algorithm that incorporates recommendations from the three major guidelines for follow-up imaging of the aortic root and ascending thoracic aorta in patients with a bicuspid aortic valve, maintaining the current recommendations with regard to surgical thresholds. PMID:26827748

  5. Transcatheter aortic valve implantation in bicuspid aortic valve stenosis.

    PubMed

    Perlman, Gidon Y; Blanke, Philipp; Webb, John G

    2016-09-18

    Bicuspid aortic stenosis (AS) is not rare in patients treated with transcatheter aortic valve implantation (TAVI). Bicuspid valves have unique anatomy which could affect the results of TAVI; however, multiple recent reports have shown that TAVI is safe and effective in this population. Paravalvular aortic regurgitation was initially found to be more frequent in bicuspid patients, but newer-generation devices have shown superior results in this respect. Higher rates of pacemaker implantation after TAVI in bicuspid AS do require further investigation. Current data suggest that bicuspid valves should not be a contraindication for TAVI, but future specific trials are needed to support this assertion. PMID:27640030

  6. Experimental and Analytical Determination of the Motion of Hydraulically Operated Valve Stems in Oil Engine Injection Systems

    NASA Technical Reports Server (NTRS)

    Gelalles, A G; Rothrock, A M

    1930-01-01

    This research on the pressure variations in the injection system of the N.A.C.A. Spray Photography Equipment and on the effects of these variations on the motion of the timing valve stem was undertaken in connection with the study of fuel injection systems for high-speed oil engines. The methods of analysis of the pressure variations and the general equation for the motion of the spring-loaded stem for the timing valve are applicable to a spring-loaded automatic injection valve, and in general to all hydraulically operated valves. A sample calculation for a spring-loaded automatic injection valve is included.

  7. Minimally invasive aortic valve surgery

    PubMed Central

    Castrovinci, Sebastiano; Emmanuel, Sam; Moscarelli, Marco; Murana, Giacomo; Caccamo, Giuseppa; Bertolino, Emanuela Clara; Nasso, Giuseppe; Speziale, Giuseppe; Fattouch, Khalil

    2016-01-01

    Aortic valve disease is a prevalent disorder that affects approximately 2% of the general adult population. Surgical aortic valve replacement is the gold standard treatment for symptomatic patients. This treatment has demonstrably proven to be both safe and effective. Over the last few decades, in an attempt to reduce surgical trauma, different minimally invasive approaches for aortic valve replacement have been developed and are now being increasingly utilized. A narrative review of the literature was carried out to describe the surgical techniques for minimally invasive aortic valve surgery and report the results from different experienced centers. Minimally invasive aortic valve replacement is associated with low perioperative morbidity, mortality and a low conversion rate to full sternotomy. Long-term survival appears to be at least comparable to that reported for conventional full sternotomy. Minimally invasive aortic valve surgery, either with a partial upper sternotomy or a right anterior minithoracotomy provides early- and long-term benefits. Given these benefits, it may be considered the standard of care for isolated aortic valve disease. PMID:27582764

  8. Flow Sizing the Cryosystem Valves

    SciTech Connect

    Kurita, C.H.; /Fermilab

    1989-01-19

    The liquid argon dewar and the three cryostats which contain the modules of the D-Zero detector are cooled and maintained at a low pressure equilibrium by the use of liquid nitrogen cooling loops. The dewar has one vacuum jacketed valve at the inlet of the cooling loop and one at the outlet. Each cryostat has two inlet valves, one for the cooldown loops and one for the operating loops. in addition to an outlet valve. The flow rate of the liquid nitrogen, and hence the valve sizes and corresponding flow coefficients (C{sub v}), is deter mined by the required cooling rate of each system. The large variance between the cooling rate required for cooldown and that required for operation, and the high control resolution required, makes the selection of a valve seat and plug difficult. The liquid valve coefficient calculations do not specifically consider the size affect of gas generated within the valve by adiabatic pressure drop. See Appendix I for a calculation of the magnitude of this effect. The figures and a graphical and tabular summary of the papers conclusions are presented in Appendix II.

  9. Minimally invasive aortic valve surgery.

    PubMed

    Castrovinci, Sebastiano; Emmanuel, Sam; Moscarelli, Marco; Murana, Giacomo; Caccamo, Giuseppa; Bertolino, Emanuela Clara; Nasso, Giuseppe; Speziale, Giuseppe; Fattouch, Khalil

    2016-09-01

    Aortic valve disease is a prevalent disorder that affects approximately 2% of the general adult population. Surgical aortic valve replacement is the gold standard treatment for symptomatic patients. This treatment has demonstrably proven to be both safe and effective. Over the last few decades, in an attempt to reduce surgical trauma, different minimally invasive approaches for aortic valve replacement have been developed and are now being increasingly utilized. A narrative review of the literature was carried out to describe the surgical techniques for minimally invasive aortic valve surgery and report the results from different experienced centers. Minimally invasive aortic valve replacement is associated with low perioperative morbidity, mortality and a low conversion rate to full sternotomy. Long-term survival appears to be at least comparable to that reported for conventional full sternotomy. Minimally invasive aortic valve surgery, either with a partial upper sternotomy or a right anterior minithoracotomy provides early- and long-term benefits. Given these benefits, it may be considered the standard of care for isolated aortic valve disease. PMID:27582764

  10. Cavitation guide for control valves

    SciTech Connect

    Tullis, J.P.

    1993-04-01

    This guide teaches the basic fundamentals of cavitation to provide the reader with an understanding of what causes cavitation, when it occurs, and the potential problems cavitation can cause to a valve and piping system. The document provides guidelines for understanding how to reduce the cavitation and/or select control valves for a cavitating system. The guide provides a method for predicting the cavitation intensity of control valves, and how the effect of cavitation on a system will vary with valve type, valve function, valve size, operating pressure, duration of operation and details of the piping installation. The guide defines six cavitation limits identifying cavitation intensities ranging from inception to the maximum intensity possible. The intensity of the cavitation at each limit Is described, including a brief discussion of how each level of cavitation influences the valve and system. Examples are included to demonstrate how to apply the method, including making both size and pressure scale effects corrections. Methods of controlling cavitation are discussed providing information on various techniques which can be used to design a new system or modify an existing one so it can operate at a desired level of cavitation.

  11. 42 CFR 84.137 - Inhalation and exhalation valves; check valves; minimum requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Inhalation and exhalation valves; check valves... PROTECTIVE DEVICES Supplied-Air Respirators § 84.137 Inhalation and exhalation valves; check valves; minimum requirements. (a) Inhalation and exhalation valves shall be provided where necessary and protected...

  12. 42 CFR 84.137 - Inhalation and exhalation valves; check valves; minimum requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Inhalation and exhalation valves; check valves... PROTECTIVE DEVICES Supplied-Air Respirators § 84.137 Inhalation and exhalation valves; check valves; minimum requirements. (a) Inhalation and exhalation valves shall be provided where necessary and protected...

  13. 49 CFR 192.145 - Valves.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Valves. 192.145 Section 192.145 Transportation... BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Design of Pipeline Components § 192.145 Valves. (a) Except for cast iron and plastic valves, each valve must meet the minimum requirements of API...

  14. 14 CFR 125.137 - Oil valves.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Oil valves. 125.137 Section 125.137....137 Oil valves. (a) Each oil valve must— (1) Comply with § 125.155; (2) Have positive stops or... the valve. (b) The closing of an oil shutoff means must not prevent feathering the propeller,...

  15. 49 CFR 195.420 - Valve maintenance.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Valve maintenance. 195.420 Section 195.420... PIPELINE Operation and Maintenance § 195.420 Valve maintenance. (a) Each operator shall maintain each valve..., inspect each mainline valve to determine that it is functioning properly. (c) Each operator shall...

  16. 14 CFR 125.137 - Oil valves.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Oil valves. 125.137 Section 125.137....137 Oil valves. (a) Each oil valve must— (1) Comply with § 125.155; (2) Have positive stops or... the valve. (b) The closing of an oil shutoff means must not prevent feathering the propeller,...

  17. 14 CFR 125.133 - Fuel valves.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Fuel valves. 125.133 Section 125.133....133 Fuel valves. Each fuel valve must— (a) Comply with § 125.155; (b) Have positive stops or suitable... operation or from accelerated flight conditions are not transmitted to the lines connected to the valve....

  18. 49 CFR 195.260 - Valves: Location.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Valves: Location. 195.260 Section 195.260... PIPELINE Construction § 195.260 Valves: Location. A valve must be installed at each of the following... Administrator finds in a particular case that valves are not justified. (f) On each side of a reservoir...

  19. 14 CFR 125.133 - Fuel valves.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Fuel valves. 125.133 Section 125.133....133 Fuel valves. Each fuel valve must— (a) Comply with § 125.155; (b) Have positive stops or suitable... operation or from accelerated flight conditions are not transmitted to the lines connected to the valve....

  20. 49 CFR 229.109 - Safety valves.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Safety valves. 229.109 Section 229.109....109 Safety valves. Every steam generator shall be equipped with at least two safety valves that have a... allowed working pressure. The safety valves shall be independently connected to the separator and...

  1. 49 CFR 195.420 - Valve maintenance.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valve maintenance. 195.420 Section 195.420... PIPELINE Operation and Maintenance § 195.420 Valve maintenance. (a) Each operator shall maintain each valve..., inspect each mainline valve to determine that it is functioning properly. (c) Each operator shall...

  2. 49 CFR 229.109 - Safety valves.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Safety valves. 229.109 Section 229.109....109 Safety valves. Every steam generator shall be equipped with at least two safety valves that have a... allowed working pressure. The safety valves shall be independently connected to the separator and...

  3. 49 CFR 192.145 - Valves.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valves. 192.145 Section 192.145 Transportation... BY PIPELINE: MINIMUM FEDERAL SAFETY STANDARDS Design of Pipeline Components § 192.145 Valves. (a) Except for cast iron and plastic valves, each valve must meet the minimum requirements of API...

  4. 21 CFR 868.5870 - Nonrebreathing valve.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5870 Nonrebreathing valve. (a) Identification. A nonrebreathing valve is a one-way valve that directs breathing gas flow to the patient and... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nonrebreathing valve. 868.5870 Section...

  5. 49 CFR 195.116 - Valves.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Valves. 195.116 Section 195.116 Transportation... PIPELINE Design Requirements § 195.116 Valves. Each valve installed in a pipeline system must comply with the following: (a) The valve must be of a sound engineering design. (b) Materials subject to...

  6. 49 CFR 195.116 - Valves.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valves. 195.116 Section 195.116 Transportation... PIPELINE Design Requirements § 195.116 Valves. Each valve installed in a pipeline system must comply with the following: (a) The valve must be of a sound engineering design. (b) Materials subject to...

  7. 21 CFR 868.5870 - Nonrebreathing valve.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5870 Nonrebreathing valve. (a) Identification. A nonrebreathing valve is a one-way valve that directs breathing gas flow to the patient and... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nonrebreathing valve. 868.5870 Section...

  8. 14 CFR 125.137 - Oil valves.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Oil valves. 125.137 Section 125.137....137 Oil valves. (a) Each oil valve must— (1) Comply with § 125.155; (2) Have positive stops or... the valve. (b) The closing of an oil shutoff means must not prevent feathering the propeller,...

  9. 14 CFR 125.137 - Oil valves.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Oil valves. 125.137 Section 125.137....137 Oil valves. (a) Each oil valve must— (1) Comply with § 125.155; (2) Have positive stops or... the valve. (b) The closing of an oil shutoff means must not prevent feathering the propeller,...

  10. 14 CFR 125.137 - Oil valves.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Oil valves. 125.137 Section 125.137....137 Oil valves. (a) Each oil valve must— (1) Comply with § 125.155; (2) Have positive stops or... the valve. (b) The closing of an oil shutoff means must not prevent feathering the propeller,...

  11. 49 CFR 192.145 - Valves.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... following: (1) The valve must have a maximum service pressure rating for temperatures that equal or exceed... percent of the pressure ratings for comparable steel valves at their listed temperature. However, a valve... performance level. A valve may not be used under operating conditions that exceed the applicable...

  12. Stemless ball valve

    NASA Technical Reports Server (NTRS)

    Burgess, Kevin (Inventor); Yakos, David (Inventor); Walthall, Bryan (Inventor)

    2012-01-01

    A stemless ball valve comprising: a right flange; left flange; ball with an axis pin and two travel pins; ball seal on either side of the ball; guide sleeve with inner walls comprising two channels; cartridge guide holder; inner magnetic cartridge; and outer magnetic cartridge. The ball is situated inside of the guide sleeve, and a travel pin is located in each of the two channels. The guide sleeve is situated inside of the cartridge guide holder, which is located adjacent to and outside of the inner magnetic cartridge and secured to the inner magnetic cartridge such that when the inner magnetic cartridge rotates, the cartridge guide holder also rotates. The cartridge guide holder is secured to the guide sleeve such that when the cartridge guide holder rotates, the travel pins move within the channels in the inner walls of the guide sleeve, thereby causing the ball to rotate.

  13. Multi-port valve

    DOEpatents

    Lewin, Keith F.

    1997-04-15

    A multi-port valve for regulating, as a function of ambient air having varying wind velocity and wind direction in an open-field control area, the distribution of a fluid, particularly carbon dioxide (CO.sub.2) gas, in a fluid distribution system so that the control area remains generally at an elevated fluid concentration or level of said fluid. The multi-port valve generally includes a multi-port housing having a plurality of outlets therethrough disposed in a first pattern of outlets and at least one second pattern of outlets, and a movable plate having a plurality of apertures extending therethrough disposed in a first pattern of apertures and at least one second pattern of apertures. The first pattern of apertures being alignable with the first pattern of outlets and the at least one second pattern of apertures being alignable with the second pattern of outlets. The first pattern of apertures has a predetermined orientation with the at least one second pattern of apertures. For an open-field control area subject to ambient wind having a low velocity from any direction, the movable plate is positioned to equally distribute the supply of fluid in a fluid distribution system to the open-field control area. For an open-field control area subject to ambient wind having a high velocity from a given direction, the movable plate is positioned to generally distribute a supply of fluid in a fluid distribution system to that portion of the open-field control area located upwind.

  14. Multi-port valve

    DOEpatents

    Lewin, K.F.

    1997-04-15

    A multi-port valve is described for regulating, as a function of ambient air having varying wind velocity and wind direction in an open-field control area, the distribution of a fluid, particularly carbon dioxide (CO{sub 2}) gas, in a fluid distribution system so that the control area remains generally at an elevated fluid concentration or level of said fluid. The multi-port valve generally includes a multi-port housing having a plurality of outlets there through disposed in a first pattern of outlets and at least one second pattern of outlets, and a movable plate having a plurality of apertures extending there through disposed in a first pattern of apertures and at least one second pattern of apertures. The first pattern of apertures being alignable with the first pattern of outlets and the at least one second pattern of apertures being alignable with the second pattern of outlets. The first pattern of apertures has a predetermined orientation with the at least one second pattern of apertures. For an open-field control area subject to ambient wind having a low velocity from any direction, the movable plate is positioned to equally distribute the supply of fluid in a fluid distribution system to the open-field control area. For an open-field control area subject to ambient wind having a high velocity from a given direction, the movable plate is positioned to generally distribute a supply of fluid in a fluid distribution system to that portion of the open-field control area located upwind. 7 figs.

  15. Check valve with poppet damping mechanism

    NASA Technical Reports Server (NTRS)

    Morris, Brian G. (Inventor)

    1993-01-01

    An inline check valve for a flow line is presented where the valve element is guided for inline travel forward and rearward of a valve sealing member and is spring biased to a closed sealing condition. One of the guides for the valve element includes a dashpot bore and plunger member to control the rate of travel of the valve element in either direction as well as provided a guiding function. The dashpot is not anchored to the valve body so that the valve can be functional even if the plunger member becomes jammed in the dashpot.

  16. Management of the Nasal Valve.

    PubMed

    Barrett, Dane M; Casanueva, Fernando J; Cook, Ted A

    2016-08-01

    The nasal valve is an important consideration in patients presenting with nasal obstruction. Controversy exists regarding the anatomy, terminology, evaluation, and management of the nasal valve. Innumerable techniques with variable effects have been described in the literature. The evidence qualifying these techniques has been plentiful, though often lacking in quality. This article reviews the controversial aspects of nasal valve management applying the best available evidence to help clarify potential areas of confusion. Future research using standardized definitions, consistent methodologies, and validated outcome measures are necessary to improve the quality of evidence and impact surgical decision-making. PMID:27400837

  17. Fluid relief and check valve

    DOEpatents

    Blaedel, K.L.; Lord, S.C.; Murray, I.

    1986-07-17

    A passive fluid pressure relief and check valve allows the relief pressure to be slaved to a reference pressure independently of the exhaust pressure. The pressure relief valve is embodied by a submerged vent line in a sealing fluid, the relief pressure being a function of the submerged depth. A check valve is embodied by a vertical column of fluid (the maximum back pressure being a function of the height of the column of fluid). The pressure is vented into an exhaust system which keeps the exhaust out of the area providing the reference pressure.

  18. Valve Health Monitoring System Utilizing Smart Instrumentation

    NASA Technical Reports Server (NTRS)

    Jensen, Scott L.; Drouant, George J.

    2006-01-01

    The valve monitoring system is a stand alone unit with network capabilities for integration into a higher level health management system. The system is designed for aiding in failure predictions of high-geared ball valves and linearly actuated valves. It performs data tracking and archiving for identifying degraded performance. The data collection types are cryogenic cycles, total cycles, inlet temperature, body temperature torsional strain, linear bonnet strain, preload position, total travel and total directional changes. Events are recorded and time stamped in accordance with the IRIG B True Time. The monitoring system is designed for use in a Class 1 Division II explosive environment. The basic configuration consists of several instrumentation sensor units and a base station. The sensor units are self contained microprocessor controlled and remotely mountable in three by three by two inches. Each unit is potted in a fire retardant substance without any cavities and limited to low operating power for maintaining safe operation in a hydrogen environment. The units are temperature monitored to safeguard against operation outside temperature limitations. Each contains 902-928 MHz band digital transmitters which meet Federal Communication Commission's requirements and are limited to a 35 foot transmission radius for preserving data security. The base-station controller correlates data from the sensor units and generates data event logs on a compact flash memory module for database uploading. The entries are also broadcast over an Ethernet network. Nitrogen purged National Electrical Manufactures Association (NEMA) Class 4 enclosures are used to house the base-station

  19. FLUID PRESSURE AND CAM OPERATED VACUUM VALVE

    DOEpatents

    Batzer, T.H.

    1963-11-26

    An ultra-high vacuum valve that is bakable, reusable, and capable of being quickly opened and closed is described. A translationally movable valve gate having an annular ridge is adapted to contact an annular soft metal gasket disposed at the valve seat such that the soft metal gasket extends beyond the annular ridge on all sides. The valve gate is closed, by first laterally aligning the valve gate with the valve seat and then bringing the valve gate and valve seat into seating contact by the translational movement of a ramp-like wedging means that engages similar ramp-like stractures at the base of the valve gate to force the valve gate into essentially pressureless contact with the annular soft metal gasket. This gasket is then pressurized from beneath by a fluid thereby effecting a vacuura tight seal between the gasket and the ridge. (AEC)

  20. Do we need sutureless or self-anchoring aortic valve prostheses?

    PubMed

    Shrestha, Malakh

    2015-03-01

    Surgical aortic valve replacement (AVR) is the 'gold standard' for the treatment of aortic valve stenosis. Due to the increasing age of the patient population (reflecting the demographic changes), the use of biological valves has increased over the past years. At the same time, a large proportion of these patients require concomitant surgical procedures in addition to AVR. Although trans-apical or trans-femoral aortic valve implantations (TAVI) have been introduced for high risk patients, they are limited to patients with isolated aortic valve pathology. Therefore, strategies for avoiding long ischemia times, as well as long periods of extra-corporeal circulation (ECC) resulting in reduced peri-operative risks should be welcomed among the surgical community. Modern 'sutureless valves' with reduced cross-clamp and cardio-pulmonary bypass times as a result of the absence of sutures, combined with excellent hemodynamics in the short and mid-term, may be an ideal solution for geriatric patients. Additionally, 'self-anchoring' valves will increase the armament of surgeons in treating 'technically difficult' group of patients needing AVR who have small calcified aortic roots and those coming back after aortic root replacement with homografts. These valves should also expand the application of minimally access AVR. Therefore, the question of whether we need 'self-anchoring valves' is not only redundant, but the time may have come for these type of valves to be considered as the 'valve of choice' for higher risk geriatric patients who may be 'high risk' for conventional valves but not ineligible for TAVIs.

  1. In vitro testing of a temporary catheter-based aortic "parachute" valve.

    PubMed

    Vandenberghe, Stijn; Salizzoni, Stefano; Bajona, Pietro; Zehr, Kenton J; Speziali, Giovanni

    2008-01-01

    Recently developed technologies allow aortic valve implantation off-pump in a beating heart. In this procedure, the native, stenotic aortic valve is not removed, but simply crushed by a pressure balloon mounted on a percutaneous catheter. Removal of the native aortic cusps before valve replacement may reduce the incidence of annular or cuspal calcium embolization and late perivalvular leaks and increase implantable valve size. However, a temporary valve system in the ascending aorta may be necessary to maintain hemodynamic stability by reducing acute aortic regurgitation and left ventricular volume overload. This study evaluates the hemodynamic effects of a wire-mounted, monoleaflet, temporary valve apparatus in a mechanical cardiovascular simulator. Aortic flow, systemic pressure and left ventricular pressure were continuously monitored. An intraluminal camera obtained real-time proximal and distal images of the valve in operation. Insertion of the parachute valve in the simulator increased diastolic pressure from 7 to 38 mm Hg. Cardiac output increased from 2.08 to 4.66 L/min and regurgitant volume decreased from 65 to 23 mL. In conclusion, placement of a temporary valve in the ascending aorta may help maintain hemodynamic stability and improve off-pump aortic valve replacement.

  2. Experimental Investigation of a Reed Valve on the Performance of a Pulse Detonation Engine

    NASA Astrophysics Data System (ADS)

    Ma, Hu; Wu, Xiao-song; Wang, Dong; Cai, Wen-xiang; Chen, Jie; Diao, Ji-yang; Chen-xi, Pei

    2013-12-01

    Valve system is an important part of pulse detonation engine (PDE). The purpose of this research was to demonstrate the feasibility of utilizing a reed valve to inject fuel/air mixture into the combustion chamber of a Pulsed Detonation Engine (PDE). Using air as oxidizer and liquid C8H18 as fuel, a series of multi-cycle detonation experiments were investigated. The experimental results indicated that the reed valve was able to realize supply control of single-tube PDE effectively, and achieved stable operation about 3 minutes at 12.5 Hz for 0.15 mm valve sheet and 30° limit baffle plate. The response time and total pressure recovery coefficient of the reed valve were influenced by valve sheet thickness and air mass flow rate. For 0.1 mm valve sheet and 45° limit baffle plate, the service life of valve sheet strikingly shortened. Some factors such as the valve sheet thickness, air mass flow rate and the limit baffle plate's angle, should be comprehensively considered to design a reed valve.

  3. Energy conservation with automatic flow control valves

    SciTech Connect

    Phillips, D.

    1984-12-01

    Automatic flow control valves are offered in a wide range of sizes starting at 1/2 in. with flow rates of 0.5 gpm and up. They are also provided with materials and end connections to meet virtually any fan-coil system requirement. Among these are copper sweat type valves; ductile iron threaded valves; male/female threaded brass valves; and combination flow control/ball valves with union ends.

  4. Mitral Valve Surgery: Current Minimally Invasive and Transcatheter Options

    PubMed Central

    Ramlawi, Basel; Gammie, James S.

    2016-01-01

    The mitral valve is a highly complex structure, the competency and function of which relies on the harmonious action of its component parts. Minimally invasive cardiac surgery (MICS) for mitral valve repair or replacement (MVR/r) has been performed successfully with incremental improvements in techniques over the past decade. These minimally invasive procedures, while attractive to patients and referring physicians, should meet the same high bar for optimal clinical outcomes and long-term durability of valve repair as traditional sternotomy procedures. The majority of MICS MVR/r procedures are performed via a right minithoracotomy approach with direct or camera-assisted visualization, with a minority of centers performing robotic MVR/r. Outcomes with MICS MVR/r have been shown to have similar morbidity and mortality rates as traditional sternotomy MV procedures but with the advantage of reduced transfusions, postoperative atrial fibrillation, and time to recovery. More recently, transcatheter mitral valve repair and replacement (TMVR/r) has become a reality. Percutaneous MV repair technology is currently FDA approved for patients with nonsurgical high-risk degenerative mitral regurgitation. Other TMVR/r technology is at various levels of preclinical and clinical investigation, although these devices are proving to be more challenging compared to transcatheter aortic valve replacement (TAVR) due to the significantly more complex mitral anatomy and the greater heterogeneity of mitral disease requiring treatment. In this article, we review current techniques for MICS MVR/r and upcoming catheter-based therapies for the mitral valve. PMID:27127558

  5. Elevated transaortic valvular gradients after combined aortic valve and mitral valve replacement: an intraoperative dilemma.

    PubMed

    Essandoh, Michael; Portillo, Juan; Zuleta-Alarcon, Alix; Castellon-Larios, Karina; Otey, Andrew; Sai-Sudhakar, Chittoor B

    2015-03-01

    High transaortic valvular gradients, after combined aortic valve and mitral valve replacement, require prompt intraoperative diagnosis and appropriate management. The presence of high transaortic valvular gradients after cardiopulmonary bypass, in this setting, can be secondary to the following conditions: prosthesis dysfunction, left ventricular outflow tract obstruction, supravalvular obstruction, prosthesis-patient mismatch, hyperkinetic left ventricle from administration of inotropes, left ventricular intracavitary gradients, pressure recovery phenomenon, and increased transvalvular blood flow resulting from hyperdynamic circulation or anemia. Transesophageal echocardiography is an extremely useful tool for timely diagnosis and treatment of this complication. We describe a case of a critically ill patient with endocarditis and acute lung injury, who presented for combined aortic valve and mitral valve replacement. Transesophageal echocardiographic assessment, post-cardiopulmonary bypass, revealed high transaortic valvular gradients due to encroachment of the mitral prosthesis strut on the left ventricular outflow tract, which was compounded by a small, hypertrophied, and hyperkinetic left ventricle. Discontinuation of inotropic support, administration of fluids, phenylephrine, and esmolol led to resolution of the high gradients and prevented further surgery. PMID:25549635

  6. Selection of hydronic balancing valves

    SciTech Connect

    Ahlgren, R.C.E.

    1998-10-01

    This paper describes the selection and setting of balance valves, which, when properly applied in the design of a hydronic system, will result in a balanced system, thus preventing over pumping without excessive energy costs.

  7. Options for Heart Valve Replacement

    MedlinePlus

    ... and links along the way. Additional resources from Adam Pick's blog: Surgeon Q&A: Taking Asymmetric Information Out of the Surgical Process with Dr. John Byrne Un dergoing Heart Valve Surgery: 6 Steps ...

  8. Two-dimensional FSI simulation of closing dynamics of a tilting disc mechanical heart valve.

    PubMed

    Govindarajan, V; Udaykumar, H S; Herbertson, L H; Deutsch, S; Manning, K B; Chandran, K B

    2010-03-01

    The fluid dynamics during valve closure resulting in high shear flows and large residence times of particles has been implicated in platelet activation and thrombus formation in mechanical heart valves. Our previous studies with bi-leaflet valves have shown that large shear stresses induced in the gap between the leaflet edge and the valve housing results in relatively high platelet activation levels whereas flow between the leaflets results in shed vortices not conducive to platelet damage. In this study we compare the result of closing dynamics of a tilting disc valve with that of a bi-leaflet valve. The two-dimensional fluid-structure interaction analysis of a tilting disc valve closure mechanics is performed with a fixed grid Cartesian mesh flow solver with local mesh refinement, and a Lagrangian particle dynamic analysis for computation of potential for platelet activation. Throughout the simulation the flow remains in the laminar regime and the flow through the gap width is marked by the development of a shear layer which separates from the leaflet downstream of the valve. Zones of re-circulation are observed in the gap between the leaflet edge and the valve housing on the major orifice region of the tilting disc valve and are seen to be migrating towards the minor orifice region. Jet flow is observed at the minor orifice region and a vortex is formed which sheds in the direction of fluid motion as observed in experiments using PIV measurements. The activation parameter computed for the tilting disc valve, at the time of closure was found to be 2.7 times greater than that of the bi-leaflet mechanical valve and was found to be in the vicinity of the minor orifice region mainly due to the migration of vortical structures from the major to the minor orifice region during the leaflet rebound of the closing phase.

  9. Flow characteristics past jellyfish and St. Vincent valves in the aortic position under physiological pulsatile flow conditions.

    PubMed

    Morsi, Y S; Sakhaeimanesh, A A

    2000-07-01

    Thrombus formation and hemolysis have been linked to the dynamic flow characteristics of heart valve prostheses. To enhance our understanding of the flow characteristics past the aortic position of a Jellyfish (JF) valve in the left ventricle, in vitro laser Doppler anemometry (LDA) measurements were carried out under physiological pulsatile flow conditions. The hemodynamic performance of the JF valve was then compared with that of the St. Vincent (SV) valve. The comparison was given in terms of mean systolic pressure drop, back flow energy losses, flow velocity, and shear stresses at various locations downstream of both valves and at cardiac outputs of 3.5 L/min, 4.5 L/min, and 6.5 L/min respectively. The results indicated that both valves created disturbed flow fields with elevated levels of turbulent shear stress as well as higher levels of turbulence in the immediate vicinity of the valve and up to 1 diameter of the pipe (D) downstream of the valve. At a location further downstream, the JF valve showed better flow characteristics than the SV in terms of velocity profiles and turbulent shear stresses. The closure volume of the SV valve was found to be 2.5 times higher than that of the JF valve. Moreover, the total back flow losses and mean systolic pressure drop also were found to be higher in the SV than the JF valve.

  10. Replacement of outboard main steam isolation valves in a boiling water reactor plant

    SciTech Connect

    Schlereth, J.R.; Pennington, D.

    1996-12-01

    Most Boiling Water Reactor plants utilize wye pattern globe valves for main steam isolation valves for both inboard and outboard isolation. These valves have required a high degree of maintenance attention in order to pass the plant local leakage rate testing (LLRT) requirements at each outage. Northern States Power made a decision in 1993 to replace the outboard valves at it`s Monticello plant with double disc gate valves. The replacement of the outboard valves was completed during the fall outage in 1994. During the spring outage in April of 1996 the first LLRT testing was performed with excellent results. This presentation will address the decision process, time requirements and planning necessary to accomplish the task as well as the performance results and cost effectiveness of replacing these components.

  11. The use of MAVIS II to integrate the modeling and analysis of explosive valve interactions

    SciTech Connect

    Ng, R.; Kwon, D.M.

    1998-12-31

    The MAVIS II computer program provides for the modeling and analysis of explosive valve interactions. This report describes the individual components of the program and how MAVIS II is used with other available tools to integrate the design and understanding of explosive valves. The rationale and model used for each valve interaction is described. Comparisons of the calculated results with available data have demonstrated the feasibility and accuracy of using MAVIS II for analytical studies of explosive valve interactions. The model used for the explosive or pyrotechnic used as the driving force in explosive valves is the most critical to be understood and modeled. MAVIS II is an advanced version that incorporates a plastic, as well as elastic, modeling of the deformations experienced when plungers are forced into a bore. The inclusion of a plastic model has greatly expanded the use of MAVIS for all categories (opening, closure, or combined) of valves, especially for the closure valves in which the sealing operation requires the plastic deformation of either a plunger or bore over a relatively large area. In order to increase its effectiveness, the use of MAVIS II should be integrated with the results from available experimental hardware. Test hardware such as the Velocity Interferometer System for Any Reflector (VISAR) and Velocity Generator test provide experimental data for accurate comparison of the actual valve functions. Variable Explosive Chamber (VEC) and Constant Explosive Volume (CEV) tests are used to provide the proper explosive equation-of-state for the MAVIS calculations of the explosive driving forces. The rationale and logistics of this integration is demonstrated through an example. A recent valve design is used to demonstrate how MAVIS II can be integrated with experimental tools to provide an understanding of the interactions in this valve.

  12. Platelet thrombosis in cardiac-valve prostheses

    SciTech Connect

    Dewanjee, M.K.

    1989-01-01

    The contribution of platelets and clotting factors in thrombosis on cardiovascular prostheses had been quantified with several tracers. Thrombus formation in vivo could be measured semiquantitatively in animal models and patients with indium-111, Technetium-99m labeled platelets, iodine-123, iodine-131 labeled fibrinogen, and In-111 and Tc-99m labeled antibody to the fibrinogen-receptor on the platelet- membrane, or fibrin. The early studies demonstrated that certain platelet-inhibitors, e.g. sulfinpyrazone, aspirin or aspirin- persantine increased platelet survival time with mechanical valves implanted in the baboon model and patients. Thrombus localization by imaging is possible for large thrombus on thrombogenic surface of prosthesis in the acute phase. The majority of thrombus was found in the sewing ring (Dacron) in the acute phase in both the mechanical and tissue valves. The amount of retained thrombus in both mechanical and tissue valves in our one-day study in the dog model was similar (< 1% if injected In-111 platelets = 5 billion platelets). As the fibrous ingrowth covered the sewing ring, the thrombus formation decreased significantly. Only a small amount of thrombus was found on the leaflets at one month in both the dog and calf models. 38 refs., 9 figs., 5 tabs.

  13. Kelly mud saver valve sub

    SciTech Connect

    Reddoch, J.A.

    1986-12-02

    A mud saver valve is described for preventing drilling mud from escaping from a kelly when a drill string is broken below the kelly, the valve comprising: a tubular valve body having first and second ends, the first end being provided with means for attachment in fluid communicating relationship with the kelly, the second end being provided with means for attachment to the drill string; an annular seat fixed in the interior of the valve body adjacent its first end; a tubular closure member within the valve body. The closure member is provided with a selectively closed seating end for seating in valve closing engagement with the annular seat, an open non-seating end in fluid communicating relationship with the drill string, and an annular expansion in the outer diameter of the closure member adjacent the seating end; a top and bottom spacer ring disposed in sliding relationship around the tubular closure member intermediate the annular expansion and the non-seating end of the closure member. The spacer ring and annular expansion cooperatively define an annular chamber around the closure member; and a helical spring disposed around the closure member towards the annular seat.

  14. Workshop on gate valve pressure locking and thermal binding

    SciTech Connect

    Brown, E.J.

    1995-07-01

    The purpose of the Workshop on Gate Valve Pressure Locking and Thermal Binding was to discuss pressure locking and thermal binding issues that could lead to inoperable gate valves in both boiling water and pressurized water reactors. The goal was to foster exchange of information to develop the technical bases to understand the phenomena, identify the components that are susceptible, discuss actual events, discuss the safety significance, and illustrate known corrective actions that can prevent or limit the occurrence of pressure locking or thermal binding. The presentations were structured to cover U.S. Nuclear Regulatory Commission staff evaluation of operating experience and planned regulatory activity; industry discussions of specific events, including foreign experience, and efforts to determine causes and alleviate the affects; and valve vendor experience and recommended corrective action. The discussions indicated that identifying valves susceptible to pressure locking and thermal binding was a complex process involving knowledge of components, systems, and plant operations. The corrective action options are varied and straightforward.

  15. A versatile valving toolkit for automating fluidic operations in paper microfluidic devices

    PubMed Central

    Toley, Bhushan J.; Wang, Jessica A.; Gupta, Mayuri; Buser, Joshua R.; Lafleur, Lisa K.; Lutz, Barry R.; Fu, Elain; Yager, Paul

    2015-01-01

    Failure to utilize valving and automation techniques has restricted the complexity of fluidic operations that can be performed in paper microfluidic devices. We developed a toolkit of paper microfluidic valves and methods for automatic valve actuation using movable paper strips and fluid-triggered expanding elements. To the best of our knowledge, this is the first functional demonstration of this valving strategy in paper microfluidics. After introduction of fluids on devices, valves can actuate automatically a) after a certain period of time, or b) after the passage of a certain volume of fluid. Timing of valve actuation can be tuned with greater than 8.5% accuracy by changing lengths of timing wicks, and we present timed on-valves, off-valves, and diversion (channel-switching) valves. The actuators require ~30 μl fluid to actuate and the time required to switch from one state to another ranges from ~5 s for short to ~50s for longer wicks. For volume-metered actuation, the size of a metering pad can be adjusted to tune actuation volume, and we present two methods – both methods can achieve greater than 9% accuracy. Finally, we demonstrate the use of these valves in a device that conducts a multi-step assay for the detection of the malaria protein PfHRP2. Although slightly more complex than devices that do not have moving parts, this valving and automation toolkit considerably expands the capabilities of paper microfluidic devices. Components of this toolkit can be used to conduct arbitrarily complex, multi-step fluidic operations on paper-based devices, as demonstrated in the malaria assay device. PMID:25606810

  16. A versatile valving toolkit for automating fluidic operations in paper microfluidic devices.

    PubMed

    Toley, Bhushan J; Wang, Jessica A; Gupta, Mayuri; Buser, Joshua R; Lafleur, Lisa K; Lutz, Barry R; Fu, Elain; Yager, Paul

    2015-03-21

    Failure to utilize valving and automation techniques has restricted the complexity of fluidic operations that can be performed in paper microfluidic devices. We developed a toolkit of paper microfluidic valves and methods for automatic valve actuation using movable paper strips and fluid-triggered expanding elements. To the best of our knowledge, this is the first functional demonstration of this valving strategy in paper microfluidics. After introduction of fluids on devices, valves can actuate automatically after a) a certain period of time, or b) the passage of a certain volume of fluid. Timing of valve actuation can be tuned with greater than 8.5% accuracy by changing lengths of timing wicks, and we present timed on-valves, off-valves, and diversion (channel-switching) valves. The actuators require ~30 μl fluid to actuate and the time required to switch from one state to another ranges from ~5 s for short to ~50 s for longer wicks. For volume-metered actuation, the size of a metering pad can be adjusted to tune actuation volume, and we present two methods - both methods can achieve greater than 9% accuracy. Finally, we demonstrate the use of these valves in a device that conducts a multi-step assay for the detection of the malaria protein PfHRP2. Although slightly more complex than devices that do not have moving parts, this valving and automation toolkit considerably expands the capabilities of paper microfluidic devices. Components of this toolkit can be used to conduct arbitrarily complex, multi-step fluidic operations on paper-based devices, as demonstrated in the malaria assay device.

  17. The Sorin Freedom SOLO stentless tissue valve: early outcomes after aortic valve replacement.

    PubMed

    Altintas, Garip; Diken, Adem Ilkay; Hanedan, Onur; Yurdakok, Okan; Ozyalcin, Sertan; Kucuker, Seref Alp; Ozatik, Mehmet Ali

    2013-01-01

    We prospectively evaluated the hemodynamic performance of the SORIN Freedom SOLO aortic bioprosthesis, a stentless bovine pericardial valve designed for supra-annular implantation. Forty patients (mean age, 71.68 ± 5.25 yr; 29 men) with severe aortic stenosis underwent aortic valve replacement from January 2008 through August 2009. Patients were evaluated by transthoracic echocardiography and clinical examination, both preoperatively and again at 6 and 24 postoperative months. Peak and mean transvalvular gradients, end-diastolic and end-systolic diameters, interventricular septal and posterior wall thicknesses, indexed volumes of ventricular mass, degrees of aortic regurgitation, and left ventricular ejection fractions were calculated echocardiographically. The valves were implanted with single polypropylene sutures. In the early postoperative period, 1 patient (2.5%) died of multiorgan failure. The mean aortic cross-clamp time was 86.05 ± 34.2 min. Echocardiographic peak gradients were 84.54 ± 16.85 mmHg (preoperative), 29.59 ± 6.27 mmHg (6 mo postoperative), and 24.33 ± 4.67 mmHg (24 mo postoperative) (P < 0.001); left ventricular mass indices were 176.26 ± 39.98 g/m(2) (preoperative), 139.21 ± 30.1 (6 mo postoperative), and 120.51 ± 23.88 g/m(2) (24 mo postoperative) (P < 0.001). During follow-up, the maximum aortic insufficiency recorded was trace, and no valve dysfunctions were observed. Temporary thrombocytopenia was documented in all patients during early postoperative follow-up (lowest level at day 3); recovery to preoperative levels occurred by day 10. The Freedom SOLO aortic bioprosthesis is an easy-to-implant valve with excellent hemodynamic performance. The thrombocytopenia appears to be a transient laboratory finding.

  18. Aortic Annular Enlargement during Aortic Valve Replacement

    PubMed Central

    Dumani, Selman; Likaj, Ermal; Dibra, Laureta; Llazo, Stavri; Refatllari, Ali

    2016-01-01

    In the surgery of aortic valve replacement is always attempted, as much as possible, to implant the larger prosthesis with the mains goals to enhance the potential benefits, to minimise transvalvular gradient, decrease left ventricular size and avoid the phenomenon of patient-prosthesis mismatch. Implantation of an ideal prosthesis often it is not possible, due to a small aortic annulus. A variety of aortic annulus enlargement techniques is reported to avoid patient-prosthesis mismatch. We present the case that has submitted four three times open heart surgery. We used Manouguian technique to enlarge aortic anulus with excellent results during the fourth time of surgery. PMID:27703574

  19. Facts and fiction surrounding the discovery of the venous valves.

    PubMed

    Scultetus, A H; Villavicencio, J L; Rich, N M

    2001-02-01

    Venous valves are delicate structures, the integrity of which is crucial for the normal function of the venous system. Their abnormalities lead to widespread disorders, ranging from chronic venous insufficiency to life-threatening thromboembolic phenomena. The discovery of the venous valves, however, has been the subject of hot controversy. Even though Fabricius ab Aquapendente is credited with the discovery by most historians, we demonstrate in this paper that other anatomists described them many years before Fabricius ab Aquapendente publicly demonstrated them in Padua in 1579. A thorough review of the historical literature surrounding the discovery of the venous valves was carried out from 1545 to the present under the supervision of the Medical History Department of our institution. Research was performed at the History of Medicine Division of the National Library of Medicine and through MEDLINE access to the medical literature. The Parisian Charles Estienne first mentioned the venous valves in his 1545 publication when he described "apophyses membranarum" in the veins of the liver. Lusitanus and Canano publicly demonstrated them in the azygos vein during cadaver dissections performed in Ferrera, Italy. The Parisian Jacques Sylvius described valves in the veins of the extremities in 1555. The work of these anatomists, however, could not achieve full recognition, because Andreas Vesalius, the leading anatomist at that time, was unable to confirm their findings and strongly denied the existence of venous valves. Vesalius's influence was so powerful that research on the subject was idle until 1579, when Fabricius ab Aquapendente "discovered" the venous valves. About the same time, the German Salomon Alberti published the first drawings of a venous valve (in 1585). William Harvey, a disciple of Fabricius ab Aquapendente, finally postulated the function of the venous valves, providing anatomical support for one of the greatest discoveries in medicine: the blood

  20. Pressure control valve. [inflating flexible bladders

    NASA Technical Reports Server (NTRS)

    Lambson, K. H. (Inventor)

    1980-01-01

    A control valve is provided which is adapted to be connected between a pressure source, such as a vacuum pump, and a pressure vessel so as to control the pressure in the vessel. The valve comprises a housing having a longitudinal bore which is connected between the pump and vessel, and a transversely movable valve body which controls the air flow through an air inlet in the housing. The valve body includes cylindrical and conical shaped portions which cooperate with reciprocally shaped portions of the housing to provide flow control. A filter in the air inlet removes foreign matter from the air. The bottom end of the valve body is screwed into the valve housing control knob formed integrally with the valve body and controls translation of the valve body, and the opening and closing of the valve.

  1. Acoustic monitoring of power-plant valves

    NASA Astrophysics Data System (ADS)

    Allen, J. W.; Hartman, W. F.; Robinson, J. C.

    1982-06-01

    Advanced surveillance diagnostics were applied to key nuclear power plant valves to improve the availability of the power plant. Two types of valves were monitored: BWR three-stage, pilot-operated safety/relief valves and PWR feedwater control valves. Excessive leakage across the pilot-disc seat in BWR safety/relief valves can cause the second-stage pressure to reach the critical value that activates the valve, even though the set pressure was not exceeded. Acoustic emissions created by the leak noise were monitored and calibrated to indicate incipient activation of the safety/relief valve. Hydrodynamic, vibration, control and process signals from PWR feedwater control valves were monitored by a mini-computer based surveillance system. On-line analysis of these signals coupled with earlier analytic modelling identified: (1) cavitation, (2) changes in steam packaging tightness, (3) valve stem torquing, (4) transducer oscillations, and (5) peak vibration levels during power transients.

  2. Noninvasive valve monitor using alternating electromagnetic field

    DOEpatents

    Eissenberg, D.M.; Haynes, H.D.; Casada, D.A.

    1993-03-16

    One or more electrical coils are carefully located on the outside of a valve body. An alternating current passing through the coil(s) results in an alternating electromagnetic field being transmitted into the valve body and valve internals. The electromagnetic field varies in intensity and polarity in the valve. As the position of a valve internal part is changed, the electromagnetic field throughout the valve body and its internals is altered. A passive receiver coil carefully located on the outside of the valve body detects the intensity of the electromagnetic field at that location as an induced electrical voltage in the coil. With the change in position of the valve internal part, there is a corresponding change in the induced voltage as a result of the alteration in the alternating electromagnetic field at that location. Changes in the voltage provide an indication of the position and motion of valve internals.

  3. Noninvasive valve monitor using alternating electromagnetic field

    DOEpatents

    Eissenberg, David M.; Haynes, Howard D.; Casada, Donald A.

    1993-01-01

    One or more electrical coils are carefully located on the outside of a valve body. An alternating current passing through the coil(s) results in an alternating electromagnetic field being transmitted into the valve body and valve internals. The electromagnetic field varies in intensity and polarity in the valve. As the position of a valve internal part is changed, the electromagnetic field throughout the valve body and its internals is altered. A passive receiver coil carefully located on the outside of the valve body detects the intensity of the electromagnetic field at that location as an induced electrical voltage in the coil. With the change in position of the valve internal part, there is a corresponding change in the induced voltage as a result of the alteration in the alternating electromagnetic field at that location. Changes in the voltage provide an indication of the position and motion of valve internals.

  4. Annular flow diverter valve

    DOEpatents

    Rider, Robert L.

    1980-01-01

    A valve for diverting flow from the center of two concentric tubes to the annulus between the tubes or, operating in the reverse direction, for mixing fluids from concentric tubes into a common tube and for controlling the volume ratio of said flow consists of a toroidal baffle disposed in sliding engagement with the interior of the inner tube downstream of a plurality of ports in the inner tube, a plurality of gates in sliding engagement with the interior of the inner tube attached to the baffle for movement therewith, a servomotor having a bullet-shaped plug on the downstream end thereof, and drive rods connecting the servomotor to the toroidal baffle, the servomotor thereby being adapted to move the baffle into mating engagement with the bullet-shaped plug and simultaneously move the gates away from the ports in the inner tube and to move the baffle away from the bullet-shaped plug and simultaneously move the gates to cover the ports in the inner tube.

  5. Numerical investigation on cavitation in pressure relief valve for coal liquefaction

    NASA Astrophysics Data System (ADS)

    Ou, G. F.; Li, W. Z.; Xiao, D. H.; Zheng, Z. J.; Dou, H. S.; Wang, C.

    2015-01-01

    The pressure relief valve for regulating the level of the high-pressure separator works under a pressure difference up to 15 MPa in the temperature of 415 °C. Severe cavitation erosion and particle impact lead to the valve disc's mass loss. In this paper, three-dimensional turbulent cavitating flows in the pressure relief valve are numerically simulated to reveal the mechanism of mass loss at valve disc. The RNG k-epsilon turbulence model and the mixture model with a mass transfer for cavitation are employed to simulate the cavitating flow in the pressure relief valve. The result shows that there is phase change in the pressure relief process and cavitation bubbles would be transported by high-velocity backflow to the head of valve disc. For the local pressure higher than the saturated vapor pressure, the bubbles collapse at the head of disc and cavitation erosion is formed at the head of the disc. By comparing the cases of opening of 40%, 50%, and 60%, backflow velocity and cavitation region in front of the disc decrease with the opening increase. Therefore, during the actual operation, the pressure relief valve should be kept to a relatively large opening.

  6. Numerical simulation and experimental study of heat-fluid-solid coupling of double flapper-nozzle servo valve

    NASA Astrophysics Data System (ADS)

    Zhao, Jianhua; Zhou, Songlin; Lu, Xianghui; Gao, Dianrong

    2015-09-01

    The double flapper-nozzle servo valve is widely used to launch and guide the equipment. Due to the large instantaneous flow rate of servo valve working under specific operating conditions, the temperature of servo valve would reach 120°C and the valve core and valve sleeve deform in a short amount of time. So the control precision of servo valve significantly decreases and the clamping stagnation phenomenon of valve core appears. In order to solve the problem of degraded control accuracy and clamping stagnation of servo valve under large temperature difference circumstance, the numerical simulation of heat-fluid-solid coupling by using finite element method is done. The simulation result shows that zero position leakage of servo valve is basically impacted by oil temperature and change of fit clearance. The clamping stagnation is caused by warpage-deformation and fit clearance reduction of the valve core and valve sleeve. The distribution rules of the temperature and thermal-deformation of shell, valve core and valve sleeve and the pressure, velocity and temperature field of flow channel are also analyzed. Zero position leakage and electromagnet's current when valve core moves in full-stroke are tested using Electro-hydraulic Servo-valve Characteristic Test-bed of an aerospace sciences and technology corporation. The experimental results show that the change law of experimental current at different oil temperatures is roughly identical to simulation current. The current curve of the electromagnet is smooth when oil temperature is below 80°C, but the amplitude of current significantly increases and the hairy appears when oil temperature is above 80°C. The current becomes smooth again after the warped valve core and valve sleeve are reground. It indicates that clamping stagnation is caused by warpage-deformation and fit clearance reduction of valve core and valve sleeve. This paper simulates and tests the heat-fluid-solid coupling of double flapper-nozzle servo

  7. Design of a cyclic pressure bioreactor for the ex vivo study of aortic heart valves.

    PubMed

    Schipke, Kimberly J; To, S D Filip; Warnock, James N

    2011-01-01

    The aortic valve, located between the left ventricle and the aorta, allows for unidirectional blood flow, preventing backflow into the ventricle. Aortic valve leaflets are composed of interstitial cells suspended within an extracellular matrix (ECM) and are lined with an endothelial cell monolayer. The valve withstands a harsh, dynamic environment and is constantly exposed to shear, flexion, tension, and compression. Research has shown calcific lesions in diseased valves occur in areas of high mechanical stress as a result of endothelial disruption or interstitial matrix damage(1-3). Hence, it is not surprising that epidemiological studies have shown high blood pressure to be a leading risk factor in the onset of aortic valve disease(4). The only treatment option currently available for valve disease is surgical replacement of the diseased valve with a bioprosthetic or mechanical valve(5). Improved understanding of valve biology in response to physical stresses would help elucidate the mechanisms of valve pathogenesis. In turn, this could help in the development of non-invasive therapies such as pharmaceutical intervention or prevention. Several bioreactors have been previously developed to study the mechanobiology of native or engineered heart valves(6-9). Pulsatile bioreactors have also been developed to study a range of tissues including cartilage(10), bone(11) and bladder(12). The aim of this work was to develop a cyclic pressure system that could be used to elucidate the biological response of aortic valve leaflets to increased pressure loads. The system consisted of an acrylic chamber in which to place samples and produce cyclic pressure, viton diaphragm solenoid valves to control the timing of the pressure cycle, and a computer to control electrical devices. The pressure was monitored using a pressure transducer, and the signal was conditioned using a load cell conditioner. A LabVIEW program regulated the pressure using an analog device to pump compressed

  8. Performance Evaluation of a High Bandwidth Liquid Fuel Modulation Valve for Active Combustion Control

    NASA Technical Reports Server (NTRS)

    Saus, Joseph R.; DeLaat, John C.; Chang, Clarence T.; Vrnak, Daniel R.

    2012-01-01

    At the NASA Glenn Research Center, a characterization rig was designed and constructed for the purpose of evaluating high bandwidth liquid fuel modulation devices to determine their suitability for active combustion control research. Incorporated into the rig s design are features that approximate conditions similar to those that would be encountered by a candidate device if it were installed on an actual combustion research rig. The characterized dynamic performance measures obtained through testing in the rig are planned to be accurate indicators of expected performance in an actual combustion testing environment. To evaluate how well the characterization rig predicts fuel modulator dynamic performance, characterization rig data was compared with performance data for a fuel modulator candidate when the candidate was in operation during combustion testing. Specifically, the nominal and off-nominal performance data for a magnetostrictive-actuated proportional fuel modulation valve is described. Valve performance data were collected with the characterization rig configured to emulate two different combustion rig fuel feed systems. Fuel mass flows and pressures, fuel feed line lengths, and fuel injector orifice size was approximated in the characterization rig. Valve performance data were also collected with the valve modulating the fuel into the two combustor rigs. Comparison of the predicted and actual valve performance data show that when the valve is operated near its design condition the characterization rig can appropriately predict the installed performance of the valve. Improvements to the characterization rig and accompanying modeling activities are underway to more accurately predict performance, especially for the devices under development to modulate fuel into the much smaller fuel injectors anticipated in future lean-burning low-emissions aircraft engine combustors.

  9. Valve system incorporating single failure protection logic

    DOEpatents

    Ryan, Rodger; Timmerman, Walter J. H.

    1980-01-01

    A valve system incorporating single failure protective logic. The system consists of a valve combination or composite valve which allows actuation or de-actuation of a device such as a hydraulic cylinder or other mechanism, integral with or separate from the valve assembly, by means of three independent input signals combined in a function commonly known as two-out-of-three logic. Using the input signals as independent and redundant actuation/de-actuation signals, a single signal failure, or failure of the corresponding valve or valve set, will neither prevent the desired action, nor cause the undesired action of the mechanism.

  10. BORED AND ASSEMBLED GATE VALVES RECEIVING PROTECTIVE COATING IN THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    BORED AND ASSEMBLED GATE VALVES RECEIVING PROTECTIVE COATING IN THE VALVE PAINT BOOTH OF THE VALVE ASSEMBLY BUILDING. - Stockham Pipe & Fittings Company, Valve Assembly Building, 4000 Tenth Avenue North, Birmingham, Jefferson County, AL

  11. [Mitral valve replacement for congenital parachute mitral valve].

    PubMed

    Sasahashi, N; Ando, F; Okamoto, F; Yamanaka, K; Hanada, T; Makino, S

    1995-07-01

    A one-year-old boy was admitted with refractory congestive biventricular heart failure for medical treatment. On echocardiogram and cardiac catheterization revealed severe mitral stenosis from parachute deformity with pulmonary hypertension. During the operation, a single round orifice of 7 mm in diameter was detected in the mitral valve and adhered chordae were attached to a large single papillary muscle which was located at the posteromedial portion of the left ventricle. An isolated muscle band which was not attached to the mitral valve was observed at the anterolateral wall of the left ventricle. The mitral valve was replaced with 16 mm Carbo-Medicus prosthesis. Postoperative catheterization revealed residual pulmonary hypertension which was responsive to Imidarine infusion. He was discharged from the hospital without any sequelae, and has been on regimen including anticoaglant and vasodilator. PMID:7561327

  12. Mechanical heart valve cavitation in patients with bileaflet valves.

    PubMed

    Johansen, Peter; Andersen, Tina S; Hasenkam, J Michael; Nygaard, Hans; Paulsen, Peter K

    2014-01-01

    Today, the quality of mechanical heart valves is quite high, and implantation has become a routine clinical procedure with a low operative mortality (< 5%). However, patients still face the risks of blood cell damage, thromboembolic events, and material failure of the prosthetic device. One mechanism found to be a possible contributor to these adverse effects is cavitation. In vitro, cavitation has been directly demonstrated by visualization and indirectly in vivo by registering of high frequency pressure fluctuations (HFPF). Tilting disc valves are thought of having higher cavitation potential than bileaflet valves due to higher closing velocities. However, the thromboembolic potential seems to be the same. Further studies are therefore needed to investigate the cavitation potential of bileaflet valves in vivo. The post processing of HFPF have shown difficulties when applied on bileaflet vavles due to asynchronous closure of the two leaflets. The aim of this study was therefore to isolate the pressure signature from each leaflet closure and perform cavitation analyses on each component. Six patients were included in the study (St. Jude Medical (n=3) and CarboMedics (n=3); all aortic bileaflet mechanical heart valves). HFPFs were recorded intraoperatively through a hydrophone at the aortic root. The pressure signature relating to the first and second leaflet closure was isolated and cavitation parameters were calculated (RMS after 50 kHz highpass filtering and signal energy). Data were averaged over 30 heart cycles. For all patients both the RMS value and signal energy of the second leaflet closure were higher than for the first leaflet closure. This indicates that the second leaflet closure is most prone to cause cavitation. Therefore, quantifying cavitation based on the HFPF related to the second leaflet closure may suggest that the cavitation potential for bileaflet valves in vivo may be higher than previous studies have suggested. PMID:25571278

  13. FLUID MECHANICS OF ARTIFICIAL HEART VALVES

    PubMed Central

    Dasi, Lakshmi P; Simon, Helene A; Sucosky, Philippe; Yoganathan, Ajit P

    2009-01-01

    SUMMARY 1. Artificial heart valves have been in use for over five decades to replace diseased heart valves. Since the first heart valve replacement performed with a caged-ball valve, more than 50 valve designs have been developed, differing principally in valve geometry, number of leaflets and material. To date, all artificial heart valves are plagued with complications associated with haemolysis, coagulation for mechanical heart valves and leaflet tearing for tissue-based valve prosthesis. For mechanical heart valves, these complications are believed to be associated with non-physiological blood flow patterns. 2. In the present review, we provide a bird’s-eye view of fluid mechanics for the major artificial heart valve types and highlight how the engineering approach has shaped this rapidly diversifying area of research. 3. Mechanical heart valve designs have evolved significantly, with the most recent designs providing relatively superior haemodynamics with very low aerodynamic resistance. However, high shearing of blood cells and platelets still pose significant design challenges and patients must undergo life-long anticoagulation therapy. Bioprosthetic or tissue valves do not require anticoagulants due to their distinct similarity to the native valve geometry and haemodynamics, but many of these valves fail structurally within the first 10–15 years of implantation. 4. These shortcomings have directed present and future research in three main directions in attempts to design superior artificial valves: (i) engineering living tissue heart valves; (ii) development of advanced computational tools; and (iii) blood experiments to establish the link between flow and blood damage. PMID:19220329

  14. Giant magnetroresistance properties of specular spin valve films in a current perpendicular to plane structure

    SciTech Connect

    Nagasaka, K.; Seyama, Y.; Varga, L.; Shimizu, Y.; Tanaka, A.

    2001-06-01

    Conventional and specular spin valve films in a current perpendicular to plane (CPP) structure have been investigated. The specular spin valve film with bottom type structure had two oxidized layers: one in the pinned layer, which was oxidized during an in situ deposition process, and the other in the free layer, which was a naturally oxidized Cu/Ta cap. Both films had increasing resistance, R, and resistance change, {Delta}R, with decreasing element size. The conventional spin valve film showed a resistance times area product, RA, of 144 m{Omega}{mu}m2 and a resistance change area product, {Delta}RA, of 0.7 m{Omega}{mu}m2 while the specular spin valve film showed RA of 1120 m{Omega}{mu}m2 and {Delta}RA of 23 m{Omega}{mu}m2. The {Delta}RA of the specular spin valve film was about 33 times larger than that of the conventional spin valve film. The calculated magnetoresistance (MR) ratios, MR{sub SV}, of each spin valve film were 1.9% and 2.3%, respectively. We think oxidized layers in the spin valve film caused the specular electron scattering and this lengthened the path of the conduction electrons, enhancing the interfacial and bulk spin dependent scattering. We estimated the output voltage change of the 0.01 {mu}m2 element, the size required for 150 Gb/in.2 recording density, of the specular spin valve film in CPP mode to be 5.3 mV. It was almost six times larger than that of the conventional spin valve film at constant power consumption. Specular spin valve film are advantageous for the CPP structure element for future giant MR sensors. {copyright} 2001 American Institute of Physics.

  15. Titanium in Engine Valve Systems

    NASA Astrophysics Data System (ADS)

    Allison, J. E.; Sherman, A. M.; Bapna, M. R.

    1987-03-01

    Titanium alloys offer a unique combination of high strength-to-weight ratio, good corrosion resistance and favorable high temperature mechanical properties. Still, their relatively high cost has discouraged consideration for widespread use in automotive components. Recent demands for increased fuel economy have led to the consideration of these alloys for use as valve train materials where higher costs might be offset by improvements in performance and fuel economy. Lighter weight valve train components permit the use of lower spring loads, thus reducing friction and increasing fuel economy. Camshaft friction measurements made on a typical small displacement engine indicate that a twoto-four percent increase in fuel economy can be achieved. Valve train components are, however, subject to a severe operating environment, including elevated temperatures, sliding wear and high mechanical loads. This paper discusses the details of alloy and heat treatment selection for optimizing valve performance. When properly manufactured, titanium valves have been shown to withstand very stringent durability testing, indicating the technical feasibility of this approach to fuel economy improvement.

  16. Large Scale Magnetostrictive Valve Actuator

    NASA Technical Reports Server (NTRS)

    Richard, James A.; Holleman, Elizabeth; Eddleman, David

    2008-01-01

    Marshall Space Flight Center's Valves, Actuators and Ducts Design and Development Branch developed a large scale magnetostrictive valve actuator. The potential advantages of this technology are faster, more efficient valve actuators that consume less power and provide precise position control and deliver higher flow rates than conventional solenoid valves. Magnetostrictive materials change dimensions when a magnetic field is applied; this property is referred to as magnetostriction. Magnetostriction is caused by the alignment of the magnetic domains in the material s crystalline structure and the applied magnetic field lines. Typically, the material changes shape by elongating in the axial direction and constricting in the radial direction, resulting in no net change in volume. All hardware and testing is complete. This paper will discuss: the potential applications of the technology; overview of the as built actuator design; discuss problems that were uncovered during the development testing; review test data and evaluate weaknesses of the design; and discuss areas for improvement for future work. This actuator holds promises of a low power, high load, proportionally controlled actuator for valves requiring 440 to 1500 newtons load.

  17. Valve packings conquer fugitive emissions

    SciTech Connect

    1995-11-01

    In the early 1990s, when the US Environmental Protection Agency (EPA; Washington, D.C.) declared its intent to regulate fugitive emissions from valve-stem leakage, much of the chemical process industries (CPI) responded with fear and uncertainty. The biggest fear was that valve packing would not meet the required limits on leak rates and that expensive bellows seals may be required on many applications. The uncertainly was about how much it would cost. Today, for the most part, these concerns have been mitigated. It is estimated that about 80--90% of valves satisfy the emission requirements. The rest need some improvement in their packing systems to meet the regulations. Generally, these valves can be brought within compliance if the packing designers follow a few basic principles: Employ less-pliable outer rings and more-pliable inner rings; and don`t use excessive packing. While interest in valve packing remains high, mechanical seals continue to become more user-friendly. Many of those covered below are designed to run dry, and some can even tolerate high shaft-wobble without damage. Also look for improved flange gaskets and a host of seals to protect bearings. Twenty-one summaries are presented on new products and services.

  18. Are bioprostheses associated with better outcome than mechanical valves in patients with chronic kidney disease requiring dialysis who undergo valve surgery?

    PubMed

    Bianchi, Giacomo; Solinas, Marco; Bevilacqua, Stefano; Glauber, Mattia

    2012-09-01

    A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether patients with chronic kidney disease who required dialysis that undergo valve surgery have better surgical recovery rates with bioprostheses than with mechanical valves. Altogether more than 96 papers were found using the reported search, of which 12 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. Patients with end stage renal disease (ESRD) undergoing cardiac surgery are very fragile, with high in-hospital mortality rates (13-36%) and limited life expectancy (15-42 months in selected studies). Two studies outlined that diabetic ESRD, neurological impairment, age at the operation and poor ventricular function are the strongest predictors of early and late morbidity and mortality. Based on American Heart Association/American College of Cardiology (AHA/ACC) 1998 valvular guidelines, bioprostheses were considered a contraindication in dialysis patients; this statement derived from anecdotal reports of accelerated valve degeneration. Structural valve deterioration was reported in only 5 of 1347 patients who received bioprosthesis through the studies and independent from implantation site. Likelihood of degeneration is low, with a calculated valve-excision rate of 7%, and occurred in a broad range of time (from 10 to 156 months). The AHA/ACC 2006 valvular revised guidelines removed the previous statement (1998) of class IIa recommendation for mechanical valves and class III for tissue valves; in the focus update of 2008, there is still no specific indication for valve selection in dialysis patients, but difficulties in maintaining anticoagulation in these patients was noted. Stroke, haemorrhage and gastro-intestinal bleeding events occurred in almost 15% of patients with mechanical

  19. Percutaneous heart valves; past, present and future.

    PubMed

    Rozeik, M M; Wheatley, D J; Gourlay, T

    2014-09-01

    Percutaneous heart valves provide a promising future for patients refused surgery on the grounds of significant technical challenges or high risk for complications. Since the first human intervention more than 10 years ago, over 50 different types of valves have been developed. The CoreValve and Edwards SAPIEN valves have both experienced clinical trials and the latter has gained FDA approval for implantation in patients considered inoperable. Current complications, such as major vascular bleeding and stroke, prevent these valves from being commonly deployed in patients considered operable in conventional surgery. This review focuses on the past and present achievements of these valves and highlights the design considerations required to progress development further. It is envisaged that, with continued improvement in valve design and with increased clinical and engineering experience, percutaneous heart valve replacement may one day be a viable option for lower-risk operable patients.

  20. Acoustic monitoring of power plant valves

    NASA Astrophysics Data System (ADS)

    Allen, J. W.; Hartman, W. F.; Robinson, J. C.

    1982-06-01

    Advanced surveillance diagnostics were applied to key nuclear power plant valves to improve the availability of the power plant. Two types of valves were monitored: boiling water reactor (BWR) three-stage, pilot-operated safety/relief valves and pressurized water reactor (PWR) feedwater control valves. Excessive leakage across the pilot-disc seat in BWR safety/relief valves can cause the second-stage pressure to reach the critical value that activates the valve, even though the set pressure was not exceeded. Acoustic emission created by the leak noise were monitored and calibrated to indicate incipient activation of the safety/relief valve. Hydrodynamic, vibration, control and process signals frm PWR feedwater control valves were monitored by a mini-computer based surveillance system.

  1. Geometry of aortic heart valves. [prosthetic design

    NASA Technical Reports Server (NTRS)

    Karara, H. M.

    1975-01-01

    Photogrammetric measurements of the surface topography of the aortic valves obtained from silicon rubber molds of freshly excised human aortic valves are presented. The data are part of an investigation into the design of a new prosthetic valve which will be a central-flow device, like the real valve and unlike previous central-occluding prostheses. Since the maximum stress on the heart valve is induced when the valve is closed and subject to diastolic back-pressure, it was decided to determine the valve geometry during diastole. That is, the molds were formed by pouring the rubber down the excised aortas, causing the valves to close. The molds were made under different pressures (20-120 torr); photogrammetry served as a vehicle for the assessment of the mold topography through the following outputs: digital models, surface profiles, and contour maps.

  2. SLM Produced Hermetically Sealed Isolation Valve

    NASA Technical Reports Server (NTRS)

    Richard, James

    2014-01-01

    Marshall Space Flight Center (MSFC) has developed a valve concept to replace traditional pyrotechnic-driven isolation valves. This paper will describe the valve design and development process. The valve design uses a stem/wedge to support a disk inside the valve. That disk hermetically seals the pressurized fluids. A release mechanism holds the stem/wedge and a large spring in place. When required to open, a solenoid is energized and pulls the release mechanism allowing the spring to pull the stem/wedge away from the disk. Now the disk is unsupported and the pressure ruptures the disk allowing flow to the outlet of the valve. This paper will provide details of this design, describe the development testing, and show the results from the valve level tests performed. Also, a trade study is presented to show the advantages of this design to a conventional pyrotechnic-based valve.

  3. SLM Produced Hermetically Sealed Isolation Valve

    NASA Technical Reports Server (NTRS)

    Richard, James A.

    2014-01-01

    Marshall Space Flight Center (MSFC) has developed a valve concept to replace traditional pyrotechnic driven isolation valves. This paper will describe the valve design and development process. The valve design uses a stem/wedge to support a disk inside the valve. That disk hermetically seals the pressurized fluids. A release mechanism holds the stem/wedge and a large spring in place. When required to open, a solenoid is energized and pulls the release mechanism allowing the spring to pull the stem/wedge away from the disk. Now the disk is unsupported and the pressure ruptures the disk allowing flow to the outlet of the valve. This paper will provide details of this design, describe the development testing, and show the results from the valve level tests performed. Also, a trade study is presented to show the advantages of this design to a conventional pyrotechnic based valve.

  4. Parachute tricuspid valve in an asymptomatic adult.

    PubMed

    Mohan, Jagdish C; Shekhar, Chandra; Mohan, Vipul; Kaur, Bimalpreet; Singh, Shivesh Kumar

    2012-01-01

    Parachute tricuspid valve is a rare anomaly usually reported in small children. This report describes transthoracic and trans-oesophageal echocardiographic (TEE) features of parachute mitral valve in an adult patient.

  5. Bistable diverter valve in microfluidics

    NASA Astrophysics Data System (ADS)

    Tesař, V.; Bandalusena, H. C. H.

    2011-05-01

    Bistable diverter valves are useful for a large number of no-moving-part flow control applications, and there is a considerable interest in using them also in microfluidics, especially for handling small pressure-driven flows. However, with decreasing Reynolds number, the Coanda effect—on which the flow diverting effect depends—becomes less effective. Authors performed a study, involving flow visualisation, PIV experiments, measurements of the flow rates, and numerical flowfield computations, aimed at clarifying behaviour of a typical fluidic valve at low Reynolds numbers. A typical fluidic valve originally developed for high Re operation was demonstrated to be useful, though with progressively limited efficiency, down to surprisingly low Re values as small as Re = 800. Also observed was a previously not reported discontinuation in the otherwise monotonic decrease in performance at Re between 1,500 and 2,000.

  6. Lost-motion valve actuator

    SciTech Connect

    Burris, W.J. III; Ringgenberg, P.D.

    1987-04-07

    A lost-motion valve actuator is described for a bore closure valve employed in a well bore, comprising: operating connector means adapted to move the bore closure valve between open and closed positions through longitudinal movement of the operating connector means. The operating connector means comprises an operating connector and a connector insert defining a recess therebetween; locking dog means comprising at least one locking dog received in the recess and spring biasing means adapted to urge at least one locking dog radially inwardly; and mandrel means slidably received within the operating connector means and including dog slot means associated therewith. The dog slot means comprises an annular slot on the exterior of the mandrel means adapted to lockingly receive at least one inwardly biased locking dog when proximate thereto, whereby longitudinal movement of the mandrel means is transmitted to the operating connector means.

  7. Novel Active Combustion Control Valve

    NASA Technical Reports Server (NTRS)

    Caspermeyer, Matt

    2014-01-01

    This project presents an innovative solution for active combustion control. Relative to the state of the art, this concept provides frequency modulation (greater than 1,000 Hz) in combination with high-amplitude modulation (in excess of 30 percent flow) and can be adapted to a large range of fuel injector sizes. Existing valves often have low flow modulation strength. To achieve higher flow modulation requires excessively large valves or too much electrical power to be practical. This active combustion control valve (ACCV) has high-frequency and -amplitude modulation, consumes low electrical power, is closely coupled with the fuel injector for modulation strength, and is practical in size and weight. By mitigating combustion instabilities at higher frequencies than have been previously achieved (approximately 1,000 Hz), this new technology enables gas turbines to run at operating points that produce lower emissions and higher performance.

  8. SLAC Linear Collider waveguide valve

    SciTech Connect

    Dean, N.R.; Fowkes, W.R.; Hoyt, M.W.; Schwarz, H.D.; Tillmann, E.F.

    1987-03-01

    A waveguide valve with a peak rf power handling capability of 70 MW and a reliable vacuum seal was needed for changing the new SLC klystrons. The original SLAC indium seal valve experienced rf breakdown above 35 MW and did not make a reliable vacuum seal. A new design was developed which incorporates the old valve housing but employs a new concept. The indium-knife edge seal has been replaced by an O-ring seal mechanism, which is transported to an rf-free environment during high power operation. The O-ring ''garage door'' seal rf currents are reduced to a manageable level through the use of an rf choke plunger which has a rejection capability in excess of 20 dB. The isolation between the high power rf and the O-ring chamber exceeds 100 dB.

  9. Active combustion flow modulation valve

    DOEpatents

    Hensel, John Peter; Black, Nathaniel; Thorton, Jimmy Dean; Vipperman, Jeffrey Stuart; Lambeth, David N; Clark, William W

    2013-09-24

    A flow modulation valve has a slidably translating hollow armature with at least one energizable coil wound around and fixably attached to the hollow armature. The energizable coil or coils are influenced by at least one permanent magnet surrounding the hollow armature and supported by an outer casing. Lorentz forces on the energizable coils which are translated to the hollow armature, increase or decrease the flow area to provide flow throttling action. The extent of hollow armature translation depends on the value of current supplied and the direction of translation depends on the direction of current flow. The compact nature of the flow modulation valve combined with the high forces afforded by the actuator design provide a flow modulation valve which is highly responsive to high-rate input control signals.

  10. Simulation for transthoracic echocardiography of aortic valve.

    PubMed

    Nanda, Navin C; Kapur, K K; Kapoor, Poonam Malhotra

    2016-01-01

    Simulation allows interactive transthoracic echocardiography (TTE) learning using a virtual three-dimensional model of the heart and may aid in the acquisition of the cognitive and technical skills needed to perform TTE. The ability to link probe manipulation, cardiac anatomy, and echocardiographic images using a simulator has been shown to be an effective model for training anesthesiology residents in transesophageal echocardiography. A proposed alternative to real-time reality patient-based learning is simulation-based training that allows anesthesiologists to learn complex concepts and procedures, especially for specific structures such as aortic valve. PMID:27397455

  11. Simulation for transthoracic echocardiography of aortic valve

    PubMed Central

    Nanda, Navin C.; Kapur, K. K.; Kapoor, Poonam Malhotra

    2016-01-01

    Simulation allows interactive transthoracic echocardiography (TTE) learning using a virtual three-dimensional model of the heart and may aid in the acquisition of the cognitive and technical skills needed to perform TTE. The ability to link probe manipulation, cardiac anatomy, and echocardiographic images using a simulator has been shown to be an effective model for training anesthesiology residents in transesophageal echocardiography. A proposed alternative to real-time reality patient-based learning is simulation-based training that allows anesthesiologists to learn complex concepts and procedures, especially for specific structures such as aortic valve. PMID:27397455

  12. 42 CFR 84.92 - Exhalation valve leakage test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Exhalation valve leakage test. 84.92 Section 84.92... Breathing Apparatus § 84.92 Exhalation valve leakage test. (a) Dry exhalation valves and valve seats will be...) Leakage between the valve and the valve seat shall not exceed 30 milliliters per minute....

  13. 42 CFR 84.158 - Exhalation valve leakage test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Exhalation valve leakage test. 84.158 Section 84... Respirators § 84.158 Exhalation valve leakage test. (a) Dry exhalation valves and valve seats will be... between the valve and valve seat shall not exceed 30 milliliters per minute....

  14. 42 CFR 84.92 - Exhalation valve leakage test.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Exhalation valve leakage test. 84.92 Section 84.92... Breathing Apparatus § 84.92 Exhalation valve leakage test. (a) Dry exhalation valves and valve seats will be...) Leakage between the valve and the valve seat shall not exceed 30 milliliters per minute....

  15. 42 CFR 84.158 - Exhalation valve leakage test.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 42 Public Health 1 2011-10-01 2011-10-01 false Exhalation valve leakage test. 84.158 Section 84... Respirators § 84.158 Exhalation valve leakage test. (a) Dry exhalation valves and valve seats will be... between the valve and valve seat shall not exceed 30 milliliters per minute....

  16. 49 CFR 179.400-19 - Valves and gages.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... liquid flow rates. All valves must be made from approved materials compatible with the lading and having... 49 Transportation 2 2010-10-01 2010-10-01 false Valves and gages. 179.400-19 Section 179.400-19...-19 Valves and gages. (a) Valves. Manually operated shut-off valves and control valves must...

  17. 46 CFR 151.20-5 - Cargo system valving requirements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... (a) through (d) of this section for stop valves or excess flow valves to be fitted at tank... stop valve and one excess flow valve shall be installed on each tank penetration, located as close as..., when in use. (d) Pressure-2 (P-2). (1) One manually operated stop valve and one excess flow valve...

  18. 46 CFR 151.20-5 - Cargo system valving requirements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... (a) through (d) of this section for stop valves or excess flow valves to be fitted at tank... stop valve and one excess flow valve shall be installed on each tank penetration, located as close as..., when in use. (d) Pressure-2 (P-2). (1) One manually operated stop valve and one excess flow valve...

  19. 5. DIABLO DAM: DETAIL VIEW OF RELIEF VALVES AT ELEVATION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. DIABLO DAM: DETAIL VIEW OF RELIEF VALVES AT ELEVATION 1044. VALVE IN FOREGROUND IS A BUTTERFLY VALVE SIX FEET IN DIAMETER; VALVE TO THE REAR IS A JOHNSON-TYPE NEEDLE VALVE BOTH VALVES WERE MANUFACTURED BY THE PELTON WATER WHEEL COMPANY, 1989. - Skagit Power Development, Diablo Dam, On Skagit River, 6.9 miles upstream from Newhalem, Newhalem, Whatcom County, WA

  20. 42 CFR 84.92 - Exhalation valve leakage test.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 1 2014-10-01 2014-10-01 false Exhalation valve leakage test. 84.92 Section 84.92... Breathing Apparatus § 84.92 Exhalation valve leakage test. (a) Dry exhalation valves and valve seats will be...) Leakage between the valve and the valve seat shall not exceed 30 milliliters per minute....

  1. 42 CFR 84.92 - Exhalation valve leakage test.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 1 2012-10-01 2012-10-01 false Exhalation valve leakage test. 84.92 Section 84.92... Breathing Apparatus § 84.92 Exhalation valve leakage test. (a) Dry exhalation valves and valve seats will be...) Leakage between the valve and the valve seat shall not exceed 30 milliliters per minute....

  2. 42 CFR 84.92 - Exhalation valve leakage test.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 1 2013-10-01 2013-10-01 false Exhalation valve leakage test. 84.92 Section 84.92... Breathing Apparatus § 84.92 Exhalation valve leakage test. (a) Dry exhalation valves and valve seats will be...) Leakage between the valve and the valve seat shall not exceed 30 milliliters per minute....

  3. Intro to Valve Guide Reconditioning. Automotive Mechanics. Valves. Instructor's Guide [and] Student Guide.

    ERIC Educational Resources Information Center

    Horner, W.

    This instructional package, one in a series of individualized instructional units on tools and techniques for repairing worn valve guides in motor vehicles, provides practical experience for students in working on cylinder heads. Covered in the module are reaming valve guides that are oversized to match a new oversized valve, reaming valve guides…

  4. Pannus Formation Leads to Valve Malfunction in the Tricuspid Position 19 Years after Triple Valve Replacement.

    PubMed

    Alskaf, Ebraham; McConkey, Hannah; Laskar, Nabila; Kardos, Attila

    2016-01-01

    The Medtronic ATS Open Pivot mechanical valve has been successfully used in heart valve surgery for more than two decades. We present the case of a patient who, 19 years following a tricuspid valve replacement with an ATS prosthesis as part of a triple valve operation following infective endocarditis, developed severe tricuspid regurgitation due to pannus formation. PMID:27355145

  5. Variable-pulse switching circuit accurately controls solenoid-valve actuations

    NASA Technical Reports Server (NTRS)

    Gillett, J. D.

    1967-01-01

    Solid state circuit generating adjustable square wave pulses of sufficient power operates a 28 volt dc solenoid valve at precise time intervals. This circuit is used for precise time control of fluid flow in combustion experiments.

  6. Automatic aorta segmentation and valve landmark detection in C-arm CT for transcatheter aortic valve implantation.

    PubMed

    Zheng, Yefeng; John, Matthias; Liao, Rui; Nöttling, Alois; Boese, Jan; Kempfert, Jörg; Walther, Thomas; Brockmann, Gernot; Comaniciu, Dorin

    2012-12-01

    Transcatheter aortic valve implantation (TAVI) is a minimally invasive procedure to treat severe aortic valve stenosis. As an emerging imaging technique, C-arm computed tomography (CT) plays a more and more important role in TAVI on both pre-operative surgical planning (e.g., providing 3-D valve measurements) and intra-operative guidance (e.g., determining a proper C-arm angulation). Automatic aorta segmentation and aortic valve landmark detection in a C-arm CT volume facilitate the seamless integration of C-arm CT into the TAVI workflow and improve the patient care. In this paper, we present a part-based aorta segmentation approach, which can handle structural variation of the aorta in case that the aortic arch and descending aorta are missing in the volume. The whole aorta model is split into four parts: aortic root, ascending aorta, aortic arch, and descending aorta. Discriminative learning is applied to train a detector for each part separately to exploit the rich domain knowledge embedded in an expert-annotated dataset. Eight important aortic valve landmarks (three hinges, three commissures, and two coronary ostia) are also detected automatically with an efficient hierarchical approach. Our approach is robust under all kinds of variations observed in a real clinical setting, including changes in the field-of-view, contrast agent injection, scan timing, and aortic valve regurgitation. Taking about 1.1 s to process a volume, it is also computationally efficient. Under the guidance of the automatically extracted patient-specific aorta model, the physicians can properly determine the C-arm angulation and deploy the prosthetic valve. Promising outcomes have been achieved in real clinical applications. PMID:22955891

  7. Pregnancy-induced remodeling of heart valves.

    PubMed

    Pierlot, Caitlin M; Moeller, Andrew D; Lee, J Michael; Wells, Sarah M

    2015-11-01

    Recent studies have demonstrated remodeling of aortic and mitral valves leaflets under the volume loading and cardiac expansion of pregnancy. Those valves' leaflets enlarge with altered collagen fiber architecture, content, and cross-linking and biphasic changes (decreases, then increases) in extensibility during gestation. This study extends our analyses to right-sided valves, with additional compositional measurements for all valves. Valve leaflets were harvested from nonpregnant heifers and pregnant cows. Leaflet structure was characterized by leaflet dimensions, and ECM composition was determined using standard biochemical assays. Histological studies assessed changes in cellular and ECM components. Leaflet mechanical properties were assessed using equibiaxial mechanical testing. Collagen thermal stability and cross-linking were assessed using denaturation and hydrothermal isometric tension tests. Pulmonary and tricuspid leaflet areas increased during pregnancy by 35 and 55%, respectively. Leaflet thickness increased by 20% only in the pulmonary valve and largely in the fibrosa (30% thickening). Collagen crimp length was reduced in both the tricuspid (61%) and pulmonary (42%) valves, with loss of crimped area in the pulmonary valve. Thermomechanics showed decreased collagen thermal stability with surprisingly maintained cross-link maturity. The pulmonary leaflet exhibited the biphasic change in extensibility seen in left side valves, whereas the tricuspid leaflet mechanics remained largely unchanged throughout pregnancy. The tricuspid valve exhibits a remodeling response during pregnancy that is significantly diminished from the other three valves. All valves of the heart remodel in pregnancy in a manner distinct from cardiac pathology, with much similarity valve to valve, but with interesting valve-specific responses in the aortic and tricuspid valves.

  8. Safety Testing of Left Ventricular Vent Valves.

    PubMed

    Gavin, Caroline; Coblentz, John; Acsell, Jeffrey R; Shackelford, Anthony G; Sistino, Joseph J

    2015-03-01

    Vent vacuum relief valves (VRVs) are used to limit the negative pressure at the ventricular vent catheter tip as well as prevent reversal of blood flow and prevention of air embolism. The purpose of this study was to evaluate the performance of three commercially available ventricular vent valves. The negative pressure at which the vent valve opened was measured at the valve inlet using high-fidelity pressure transducers. Also, the flow rate at which air entrainment occurred due to valve opening was recorded. Using a 51.5 cm column of saline, the resistance for each valve was calculated. The mean ± SD opening negative pressures were -231.3 ± 35.2 mmHg for the Quest Medical valve, -219.8 mmHg ± 17.2 for the Sorin valve, and -329.6 · 38.0 mmHg for the Terumo valve. The red Quest Medical valve opened at a lower flow (1.44 ± .03 L/min) than the dark blue Sorin valve (2.93 ± .01 L/min) and light blue LH130 Terumo valve (2.36 ± .02 L/min). The Sorin valve had the least resistance of 34.1 dyn-s/cm, followed by the Terumo LH130 valve resistance of 58.1 dyn·s/cm5, and the Quest Medical VRV-II valve with a resistance of 66.5 dyn·s/cm. We found that the valves are significantly different in the negative pressure generated. Understanding the limitations of these devices is important to reduce the occurrence of adverse events associated with venting and to select the best device for a specific clinical application.

  9. Aortic Valve Surgery: Minimally Invasive Options

    PubMed Central

    Ramlawi, Basel; Bedeir, Kareem; Lamelas, Joseph

    2016-01-01

    Minimally invasive aortic valve surgery has not been adopted by a significant proportion of cardiac surgeons despite proven benefits. This may be related to a high learning curve and technical issues requiring retraining. In this review, we discuss the data for minimally invasive aortic valve surgery and describe our operative technique for both ministernotomy and anterior thoracotomy approaches. We also discuss the advent of novel sutureless valves and how these techniques compare to available transcatheter aortic valve procedures. PMID:27127559

  10. Design and Development of a Large Diameter, High Pressure, Fast Acting Propulsion Valve and Valve Actuator

    NASA Technical Reports Server (NTRS)

    Srinivasan, K. V.

    1986-01-01

    This paper describes the design and development of a large diameter high pressure quick acting propulsion valve and valve actuator. The valve is the heart of a major test facility dedicated to conducting full scale performance tests of aircraft landing gear systems. The valve opens in less than 300 milliseconds releasing a 46 cm (18 in) diameter water jet and closes in 300 milliseconds. The four main components of the valve, i.e., valve body, safety shutter, high speed shutter, and pneumatic-hydraulic actuator, are discussed. This valve is unique and may have other aerospace and industrial applications.

  11. Design and development of a large diameter high pressure fast acting propulsion valve and valve actuator

    NASA Technical Reports Server (NTRS)

    Srinivasan, K. V.

    1986-01-01

    The design and development of a large diameter high pressure quick acting propulsion valve and valve actuator is described. The valve is the heart of a major test facility dedicated to conducting full scale performance tests of aircraft landing systems. The valve opens in less than 300 milliseconds releasing a 46-centimeter- (18-in.-) diameter water jet and closes in 300 milliseconds. The four main components of the valve, i.e., valve body, safety shutter, high speed shutter, and pneumatic-hydraulic actuator, are discussed. This valve is unique and may have other aerospace and industrial applications.

  12. Ultrasound based mitral valve annulus tracking for off-pump beating heart mitral valve repair

    NASA Astrophysics Data System (ADS)

    Li, Feng P.; Rajchl, Martin; Moore, John; Peters, Terry M.

    2014-03-01

    Mitral regurgitation (MR) occurs when the mitral valve cannot close properly during systole. The NeoChordtool aims to repair MR by implanting artificial chordae tendineae on flail leaflets inside the beating heart, without a cardiopulmonary bypass. Image guidance is crucial for such a procedure due to the lack of direct vision of the targets or instruments. While this procedure is currently guided solely by transesophageal echocardiography (TEE), our previous work has demonstrated that guidance safety and efficiency can be significantly improved by employing augmented virtuality to provide virtual presentation of mitral valve annulus (MVA) and tools integrated with real time ultrasound image data. However, real-time mitral annulus tracking remains a challenge. In this paper, we describe an image-based approach to rapidly track MVA points on 2D/biplane TEE images. This approach is composed of two components: an image-based phasing component identifying images at optimal cardiac phases for tracking, and a registration component updating the coordinates of MVA points. Preliminary validation has been performed on porcine data with an average difference between manually and automatically identified MVA points of 2.5mm. Using a parallelized implementation, this approach is able to track the mitral valve at up to 10 images per second.

  13. Brucella Endocarditis in Prosthetic Valves

    PubMed Central

    Mehanic, Snjezana; Mulabdic, Velida; Baljic, Rusmir; Hadzovic-Cengic, Meliha; Pinjo, Fikret; Hadziosmanovic, Vesna; Topalovic, Jasna

    2012-01-01

    SUMMARY CONFLICT OF INTEREST: none declared. Introduction Brucella endocarditis (BE) is a rare but severe and potentially lethal manifestation of brucellosis. Pre-existing valves lesions and prosthetic valves (PV) are favorable for BE. Case report We represent the case of a 46-year-old man who was treated at the Clinic for Infectious Diseases, Clinical Center of Sarajevo University, as blood culture positive (Brucella melitensis) mitral and aortic PV endocarditis. He was treated with combined anti-brucella and cardiac therapy. Surgical intervention was postponed due to cardiac instability. Four months later he passed away. Surgery was not performed. PMID:24493988

  14. TWO-WAY FREEZE VALVE

    DOEpatents

    Lantz, K.D.; Clark, P.M.

    1960-01-01

    A valve for closing off the flow of radioactive and corrosive gases and liquids or mixtures thereof and forming a leak tight barrier is described. This valve has no mechanical moving parts which would require design to close tolerances and retention of the usual seal tighthess. Instead, there is provided a cavity in which a fusible metal is contained. Heating and cooling are provided to exercise control over the state of the metal. Baffle chambers are utilized to separate the molten fusible metal from the gas or liquid which is being passed through and return the molten metal to its cavity.

  15. Fast-acting valve actuator

    DOEpatents

    Cho, Nakwon

    1980-01-01

    A fast-acting valve actuator utilizes a spring driven pneumatically loaded piston to drive a valve gate. Rapid exhaust of pressurized gas from the pneumatically loaded side of the piston facilitates an extremely rapid piston stroke. A flexible selector diaphragm opens and closes an exhaust port in response to pressure differentials created by energizing and de-energizing a solenoid which controls the pneumatic input to the actuator as well as selectively providing a venting action to one side of the selector diaphragm.

  16. Organic Evaporator steam valve failure

    SciTech Connect

    Jacobs, R. A.

    1992-09-29

    DWPF Technical has requested an analysis of the capacity of the organic Evaporator (OE) condenser (OEC) be performed to determine its capability in the case where the OE steam flow control valve fails open. Calculations of the OE boilup and the OEC heat transfer coefficient indicate the OEC will have more than enough capacity to remove the heat at maximum OE boilup. In fact, the Salt Cell Vent Condenser (SCVC) should also have sufficient capacity to handle the maximum OE boilup. Therefore it would require simultaneous loss of OEC and/or SCVC condensing capacity for the steam valve failure to cause high benzene in the Process Vessel Vent System (PVVS).

  17. [An Exploratory Study of Methods for Quantifying the Analysis of Human Aggression. Avoidance of Time-Out from, and Withdrawal of, Positive Reinforcement in Humans: Reduction in Actual and Potential Reinforcement as a Stimulus for Aggression.

    ERIC Educational Resources Information Center

    Svinicki, Marilla Scott; Symannek, Brigitte

    The first of these two articles presents the methods, results, and discussions of six experiments which employed an avoidance of time-out from positive reinforcement schedule with human subjects to investigate: (1) whether time-outs may be considered aversive events; and (2) if so, whether the aversiveness was sufficient to produce aggressive…

  18. Valve health monitoring system utilizing smart instrumentation

    NASA Astrophysics Data System (ADS)

    Jensen, Scott L.; Drouant, George J.

    2006-05-01

    The valve monitoring system is a stand alone unit with network capabilities for integration into a higher level health management system. The system is designed for aiding in failure predictions of high-geared ball valves and linearly actuated valves. It performs data tracking and archiving for identifying degraded performance. The data collection types are: cryogenic cycles, total cycles, inlet temperature, outlet temperature, body temperature, torsional strain, linear bonnet strain, preload position, total travel, and total directional changes. Events are recorded and time stamped in accordance with the IRIG B True Time. The monitoring system is designed for use in a Class 1 Division II explosive environment. The basic configuration consists of several instrumentation sensor units and a base station. The sensor units are self contained microprocessor controlled and remotely mountable in three by three by two inches. Each unit is potted in a fire retardant substance without any cavities and limited to low operating power for maintaining safe operation in a hydrogen environment. The units are temperature monitored to safeguard against operation outside temperature limitations. Each contains 902-928 MHz band digital transmitters which meet Federal Communication Commissions requirements and are limited to a 35 foot transmission radius for preserving data security. The base-station controller correlates related data from the sensor units and generates data event logs on a compact flash memory module for database uploading. The entries are also broadcast over an Ethernet network. Nitrogen purged National Electrical Manufactures Association (NEMA) Class 4 Enclosures are used to house the base-station.

  19. Improved fluid control valve extends diaphragm life

    NASA Technical Reports Server (NTRS)

    Mac Glashan, W. F.

    1965-01-01

    Wear resistance of flexible diaphragms in fluid control valves is increased by incorporating a soft rubber washer at the bottom of the piston, a flexible buffer between the diaphragm and the valve seat, and a fluid feedback arrangement. The stress and wear of components at the valve seat are minimized.

  20. Staphylococcus saprophyticus causing native valve endocarditis.

    PubMed

    Garduño, Eugenio; Márquez, Irene; Beteta, Alicia; Said, Ibrahim; Blanco, Javier; Pineda, Tomás

    2005-01-01

    Coagulase negative staphylococci are a rare cause of native valve endocarditis. Staphylococcus saprophyticus is a coagulase-negative Staphylococcus infrequently reported as a human pathogen, and most of the cases reported are urinary tract infections. We describe a case of native valve endocarditis attributed to this organism. The patient needed valve replacement due to heart failure.

  1. 49 CFR 192.145 - Valves.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...-temperature ratings contained in those requirements. (b) Each cast iron and plastic valve must comply with the following: (1) The valve must have a maximum service pressure rating for temperatures that equal or exceed the maximum service temperature. (2) The valve must be tested as part of the manufacturing, as...

  2. 49 CFR 192.145 - Valves.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...-temperature ratings contained in those requirements. (b) Each cast iron and plastic valve must comply with the following: (1) The valve must have a maximum service pressure rating for temperatures that equal or exceed the maximum service temperature. (2) The valve must be tested as part of the manufacturing, as...

  3. 46 CFR 169.570 - Lockout valves.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Lockout valves. 169.570 Section 169.570 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Lifesaving and Firefighting Equipment Firefighting Equipment § 169.570 Lockout valves. (a) A lockout valve...

  4. 46 CFR 169.570 - Lockout valves.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Lockout valves. 169.570 Section 169.570 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Lifesaving and Firefighting Equipment Firefighting Equipment § 169.570 Lockout valves. (a) A lockout valve...

  5. 14 CFR 25.995 - Fuel valves.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel valves. 25.995 Section 25.995... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System Components § 25.995 Fuel valves. In addition to the requirements of § 25.1189 for shutoff means, each fuel valve must— (a) (b) Be supported...

  6. 14 CFR 25.995 - Fuel valves.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Fuel valves. 25.995 Section 25.995... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System Components § 25.995 Fuel valves. In addition to the requirements of § 25.1189 for shutoff means, each fuel valve must— (a) (b) Be supported...

  7. 49 CFR 195.258 - Valves: General.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valves: General. 195.258 Section 195.258... PIPELINE Construction § 195.258 Valves: General. (a) Each valve must be installed in a location that is accessible to authorized employees and that is protected from damage or tampering. (b) Each submerged...

  8. 14 CFR 121.235 - Fuel valves.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Fuel valves. 121.235 Section 121.235..., FLAG, AND SUPPLEMENTAL OPERATIONS Special Airworthiness Requirements § 121.235 Fuel valves. Each fuel valve must— (a) Comply with § 121.257; (b) Have positive stops or suitable index provisions in the...

  9. 14 CFR 121.239 - Oil valves.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Oil valves. 121.239 Section 121.239..., FLAG, AND SUPPLEMENTAL OPERATIONS Special Airworthiness Requirements § 121.239 Oil valves. (a) Each oil valve must— (1) Comply with § 121.257; (2) Have positive stops or suitable index provisions in the...

  10. 14 CFR 121.239 - Oil valves.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Oil valves. 121.239 Section 121.239..., FLAG, AND SUPPLEMENTAL OPERATIONS Special Airworthiness Requirements § 121.239 Oil valves. (a) Each oil valve must— (1) Comply with § 121.257; (2) Have positive stops or suitable index provisions in the...

  11. 14 CFR 27.995 - Fuel valves.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Fuel valves. 27.995 Section 27.995... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Fuel System Components § 27.995 Fuel valves. (a) There must be a positive, quick-acting valve to shut off fuel to each engine individually. (b) The control...

  12. 14 CFR 25.1025 - Oil valves.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Oil valves. 25.1025 Section 25.1025... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Oil System § 25.1025 Oil valves. (a) Each oil shutoff... feathering. (c) Each oil valve must have positive stops or suitable index provisions in the “on” and...

  13. 14 CFR 29.1025 - Oil valves.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Oil valves. 29.1025 Section 29.1025... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Oil System § 29.1025 Oil valves. (a) Each oil shutoff.... (c) Each oil valve must have positive stops or suitable index provisions in the “on” and...

  14. 14 CFR 29.995 - Fuel valves.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel valves. 29.995 Section 29.995... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Fuel System Components § 29.995 Fuel valves. In addition to meeting the requirements of § 29.1189, each fuel valve must— (a) (b) Be supported so that no...

  15. 49 CFR 195.258 - Valves: General.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Valves: General. 195.258 Section 195.258... PIPELINE Construction § 195.258 Valves: General. (a) Each valve must be installed in a location that is accessible to authorized employees and that is protected from damage or tampering. (b) Each submerged...

  16. 14 CFR 27.995 - Fuel valves.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel valves. 27.995 Section 27.995... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Fuel System Components § 27.995 Fuel valves. (a) There must be a positive, quick-acting valve to shut off fuel to each engine individually. (b) The control...

  17. 14 CFR 121.235 - Fuel valves.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Fuel valves. 121.235 Section 121.235..., FLAG, AND SUPPLEMENTAL OPERATIONS Special Airworthiness Requirements § 121.235 Fuel valves. Each fuel valve must— (a) Comply with § 121.257; (b) Have positive stops or suitable index provisions in the...

  18. 14 CFR 29.1025 - Oil valves.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Oil valves. 29.1025 Section 29.1025... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Oil System § 29.1025 Oil valves. (a) Each oil shutoff.... (c) Each oil valve must have positive stops or suitable index provisions in the “on” and...

  19. 14 CFR 29.995 - Fuel valves.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Fuel valves. 29.995 Section 29.995... STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Fuel System Components § 29.995 Fuel valves. In addition to meeting the requirements of § 29.1189, each fuel valve must— (a) (b) Be supported so that no...

  20. 14 CFR 25.1025 - Oil valves.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Oil valves. 25.1025 Section 25.1025... STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Oil System § 25.1025 Oil valves. (a) Each oil shutoff... feathering. (c) Each oil valve must have positive stops or suitable index provisions in the “on” and...