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Sample records for valve closure member

  1. Water hammer caused by closure of turbine safety spherical valves

    Science.gov (United States)

    Karadžić, U.; Bergant, A.; Vukoslavčević, P.

    2010-08-01

    This paper investigates water hammer effects caused by closure of spherical valves against the discharge. During the first phase of modernisation of Perućica high-head hydropower plant (HPP), Montenegro, safety spherical valves (inlet turbine valves) have been refurbished on the first two Pelton turbine units. The valve closure is controlled by the valve actuator (hydraulic servomotor). Because the torque acting on the valve body is dependent on flow conditions the valve closing time may vary significantly for different flow velocities (passive valve). For the passive valve the torques acting on the valve body should be considered in the valve model. The valve closing time results from numerical simulation. On the contrary, for the active valve the valve closing time is assumed prior to simulation. The spherical valve boundary condition is incorporated into the method of characteristics (MOC) algorithm. The staggered (diamond) grid in applying the MOC is used in this paper. The passive valve boundary condition is described by the water hammer equations, the valve equation that relates discharge to pressure head drop and the dynamic equation of the valve body motion (torque equation). The active valve boundary condition is described by the first two equations, respectively. Standard quasi-steady friction model is used for estimating friction losses in plant's tunnel and penstocks. Numerical results using both the active and the passive spherical valve models are compared with results of measurements. It has been found that the influence of flow conditions on the spherical valve closing time is minor for the cases considered. Computed and measured results agree reasonably well.

  2. Water hammer caused by closure of turbine safety spherical valves

    International Nuclear Information System (INIS)

    Karadzic, U; Vukoslavcevic, P; Bergant, A

    2010-01-01

    This paper investigates water hammer effects caused by closure of spherical valves against the discharge. During the first phase of modernisation of Perucica high-head hydropower plant (HPP), Montenegro, safety spherical valves (inlet turbine valves) have been refurbished on the first two Pelton turbine units. The valve closure is controlled by the valve actuator (hydraulic servomotor). Because the torque acting on the valve body is dependent on flow conditions the valve closing time may vary significantly for different flow velocities (passive valve). For the passive valve the torques acting on the valve body should be considered in the valve model. The valve closing time results from numerical simulation. On the contrary, for the active valve the valve closing time is assumed prior to simulation. The spherical valve boundary condition is incorporated into the method of characteristics (MOC) algorithm. The staggered (diamond) grid in applying the MOC is used in this paper. The passive valve boundary condition is described by the water hammer equations, the valve equation that relates discharge to pressure head drop and the dynamic equation of the valve body motion (torque equation). The active valve boundary condition is described by the first two equations, respectively. Standard quasi-steady friction model is used for estimating friction losses in plant's tunnel and penstocks. Numerical results using both the active and the passive spherical valve models are compared with results of measurements. It has been found that the influence of flow conditions on the spherical valve closing time is minor for the cases considered. Computed and measured results agree reasonably well.

  3. Water hammer caused by closure of turbine safety spherical valves

    Energy Technology Data Exchange (ETDEWEB)

    Karadzic, U; Vukoslavcevic, P [Faculty of Mechanical Engineering, University of Montenegro Dzordza Vasingtona nn, Podgorica, 81000 (Montenegro); Bergant, A, E-mail: uros.karadzic@ac.m [LitostrojPower d.o.o., Litostrojska 50, Ljubljana, 1000 (Slovenia)

    2010-08-15

    This paper investigates water hammer effects caused by closure of spherical valves against the discharge. During the first phase of modernisation of Perucica high-head hydropower plant (HPP), Montenegro, safety spherical valves (inlet turbine valves) have been refurbished on the first two Pelton turbine units. The valve closure is controlled by the valve actuator (hydraulic servomotor). Because the torque acting on the valve body is dependent on flow conditions the valve closing time may vary significantly for different flow velocities (passive valve). For the passive valve the torques acting on the valve body should be considered in the valve model. The valve closing time results from numerical simulation. On the contrary, for the active valve the valve closing time is assumed prior to simulation. The spherical valve boundary condition is incorporated into the method of characteristics (MOC) algorithm. The staggered (diamond) grid in applying the MOC is used in this paper. The passive valve boundary condition is described by the water hammer equations, the valve equation that relates discharge to pressure head drop and the dynamic equation of the valve body motion (torque equation). The active valve boundary condition is described by the first two equations, respectively. Standard quasi-steady friction model is used for estimating friction losses in plant's tunnel and penstocks. Numerical results using both the active and the passive spherical valve models are compared with results of measurements. It has been found that the influence of flow conditions on the spherical valve closing time is minor for the cases considered. Computed and measured results agree reasonably well.

  4. Method for estimating steam hammer effects on swing-check valves during closure

    International Nuclear Information System (INIS)

    Uram, E.M.

    1976-01-01

    Relationships are developed for estimating the disk impact velocity resulting from a free swing closure of swing-check valves in normal flow and for pipe rupture. They derive from a phase-plane solution of the differential equation for the disk motion that accounts for the nature of the valve pressure drop variation due to steam-hammer effects during closure. For closure in normal flow, the method presented has a more correct foundation than that given in reference where a constant, average valve pressure differential based upon the steady-state pressure drop for the total piping system (which has no real relationship to the steam-hammer-induced valve pressure changes during the closure transient) is used in the valve disk motion equation

  5. Durability of central aortic valve closure in patients with continuous flow left ventricular assist devices.

    Science.gov (United States)

    McKellar, Stephen H; Deo, Salil; Daly, Richard C; Durham, Lucian A; Joyce, Lyle D; Stulak, John M; Park, Soon J

    2014-01-01

    A competent aortic valve is essential to providing effective left ventricular assist device support. We have adopted a practice of central aortic valve closure by placing a simple coaptation stitch at left ventricular assist device implantation in patients with significant aortic insufficiency. We conducted a follow-up study to evaluate the efficacy and durability of this procedure. The study included patients who had undergone continuous flow left ventricular assist device implantation. The patients were divided into 2 groups, those who did not require any aortic procedure because the valve was competent and those who underwent central aortic valve closure for mild or greater aortic regurgitation. The clinical endpoints were mortality, progression or recurrence of aortic insufficiency, and reoperation for aortic valve pathologic features. Aortic insufficiency was measured qualitatively from mild to severe on a scale of 0 to 5. A total of 123 patients received continuous flow left ventricular assist devices from February 2007 to August 2011. Of those, 18 (15%) underwent central aortic valve closure at left ventricular assist device implantation because of significant aortic insufficiency (1.8 ± 1.4) and 105 who did not (competent aortic valve, 0.15 ± 0.43; P assist device-supported patients, with follow-up extending into 2 years. Although aortic insufficiency progressed over time in those with minimal native valve regurgitation initially, no such progression was noted in those with central aortic valve closure. Additional investigation is needed to evaluate whether prophylactic central aortic valve closure should be performed at left ventricular assist device implantation to avoid problematic aortic regurgitation developing over time, in particular in patients undergoing left ventricular assist device implantation for life-long (destination therapy) support. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights

  6. HDR-investigations of check valve closure and resultant water hammer effects

    International Nuclear Information System (INIS)

    Scholl, K.D.

    1983-01-01

    The presented investigations are based on the Loss of Coolant Accident (LOCA). They concentrate on the first blowdown phase after pipe break of a feedwater line. The effect of such a break is moderated by quick closing check valves, by which the loss of coolant water is reduced and optimal post accident conditions are obtained. Unfortunately the closure of the valve can cause high pressure peaks (water hammer effects) in the feedwater system which potentially could produce safety relevant secondary damage. The system loading by these effects has been analysed. The HDR-Investigation-results led to an improvement of the feedwater system safety by verifying damping measures of quick closing check valves. Pressure peaks obtained with undamped valves in the range of 300 bars, are reduced to zero or a few bars above the normal operation pressure in feedwater systems. For the analytical simulation of valve closure the following dominant acting forces are identified: the blowdown flow resistance of the valve cone and the damping pistong force. The analytical description and quantification of the forces depends on blowdown flow and valve friction parameters. These have been evaluated and are presented for practical use. (orig.)

  7. Timing tests: automatic valve closure for tritium leaks

    International Nuclear Information System (INIS)

    Hanel, S.

    1976-01-01

    How fast can an automotive valve be closed after a tritium leak occurs in a system. Tests described found that a valve can be closed within fifteen seconds of leakage. In one practical example considered, this delay would limit loss of tritium from a plumbing leak in a tritium system to 1 1 / 4 g. The tests were made in a typical LLL air-flush hood in which a tritium handling system had been installed. Incidental observations suggest that further study be made of a possible leak-actuated recovery system for an entire tritium facility

  8. Pressure disequilibria induced by rapid valve closure in noble gas extraction lines

    Science.gov (United States)

    Morgan, Leah; Davidheiser-Kroll, Brett

    2015-01-01

    Pressure disequilibria during rapid valve closures can affect calculated molar quantities for a range of gas abundance measurements (e.g., K-Ar geochronology, (U-Th)/He geochronology, noble gas cosmogenic chronology). Modeling indicates this effect in a system with a 10 L reservoir reaches a bias of 1% before 1000 pipette aliquants have been removed from the system, and a bias of 10% before 10,000 aliquants. Herein we explore the causes and effects of this problem, which is the result of volume changes during valve closure. We also present a solution in the form of an electropneumatic pressure regulator that can precisely control valve motion. This solution reduces the effect to ∼0.3% even after 10,000 aliquants have been removed from a 10 L reservoir.

  9. Pressure disequilibria induced by rapid valve closure in noble gas extraction lines

    Science.gov (United States)

    Morgan, Leah E.; Davidheiser-Kroll, Brett

    2015-06-01

    Pressure disequilibria during rapid valve closures can affect calculated molar quantities for a range of gas abundance measurements (e.g., K-Ar geochronology, (U-Th)/He geochronology, noble gas cosmogenic chronology). Modeling indicates this effect in a system with a 10 L reservoir reaches a bias of 1% before 1000 pipette aliquants have been removed from the system, and a bias of 10% before 10,000 aliquants. Herein we explore the causes and effects of this problem, which is the result of volume changes during valve closure. We also present a solution in the form of an electropneumatic pressure regulator that can precisely control valve motion. This solution reduces the effect to ˜0.3% even after 10,000 aliquants have been removed from a 10 L reservoir.

  10. RETRAN simulation of Oyster Creek MSIV closure and bypass valve tests

    International Nuclear Information System (INIS)

    Alammar, M.A.

    1987-01-01

    A series of benchmarks against start-up tests have been performed on the Oyster Creek boiling water reactor unit 2 RETRAN model in support of developing an in-house reload capability. The liquid and the pressure regulator models have been benchmarked against level and pressure setpoint changes, where small setpoint perturbations were made at rated power. The purpose of the present benchmark is to check the liquid level behavior during a severe level drop as during void collapse following a scram and to size the bypass valves by benchmarking the valves' contraction coefficient. The main steam isolation valves (MSIVs) closure start-up test was chosen for the former, while the bypass valve test was chosen for the latter. The two benchmarks complete the qualification of the upper downcomer liquid level for small and large level changes and the pressure regulator system for the Oyster Creek RETRAN model

  11. Risk-based approach to appraise valve closure in the clam Corbicula fluminea in response to waterborne metals

    International Nuclear Information System (INIS)

    Liao, C.-M.; Jou, L.-J.; Chen, B.-C.

    2005-01-01

    We developed a risk-based approach to assess how the valve closure behavior of Asiatic clam Corbicula fluminea responds to waterborne copper (Cu) and cadmium (Cd). We reanalyzed the valve closure response data from published literature to reconstruct the response time-dependent dose-response profiles based on an empirical three-parameter Hill equation model. We integrated probabilistic exposure profiles of measured environmental Cu and Cd concentrations in the western coastal areas of Taiwan with the reconstructed dose-response relationships at different integration times of response to quantitatively estimate the valve response risk. The risk assessment results implicate exposure to waterborne Cu and Cd may pose no significant risk to clam valve activity in the short-time response periods (e.g., <30 min), yet a relative high risk for valve closure response to waterborne Cu at response times greater than 120 min is alarming. We successfully linked reconstructed dose-response profiles and EC50-time relationships associated with the fitted daily valve opening/closing rhythm characterized by a three-parameter lognormal function to predict the time-varying bivalve closure rhythm response to waterborne metals. We parameterized the proposed predictive model that should encourage a risk-management framework for discussion of future design of biological monitoring systems. - A model was developed to link valve closure in clams to concentrations of metals in water

  12. Strength and water-tightness of the closure head and valves of a model cask under high external pressure

    International Nuclear Information System (INIS)

    Terada, O.; Kumada, M.; Hayakawa, T.; Mochizuki, S.; Ohrui, K.

    1978-01-01

    This paper describes experimental research on the strength and water-tightness of the closure head and attached valves of a model cask under high external pressure, in simulation of its having been accidentally lost in the deep sea. Both the external pressure tests and the corrosion tests were carried out using scale models of the closure head of an 80-ton spent-fuel shipping cask, and the full size pressure relief valves and drain valves which were to be attached to the actual cask. Based on the results of the above tests, evaluations were made, and new information was obtained on the pressure-proof strength and water-tightness of the closure head of the cask and the valves. Lastly, research which is being carried on in Japan on the pressure equalizer is also introduced

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

    Science.gov (United States)

    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.

  14. The transient analysis of single turbine control valve closure for Lungmen ABWR

    International Nuclear Information System (INIS)

    Ma Shaoshih; Yuann Yngruey; Shih Chunkuan

    2012-01-01

    Highlights: ► The LRM was used to evaluate the single control valve closure event. ► The purpose is to offer an updated analysis about the MCFL under the partial arc mode instead of FSAR’s result. ► It is concluded that the 112% MCFL setting is the most limiting case. ► The MCFL setting actually used in SBPCS must be kept between 112% to 114% to gain the operational margin. ► The HFF index defined by the normalized heat flux can be used to predict the CPR change. - Abstract: The single control valve closure in fast (SCVCF) event is the most limiting transient in terms of delta critical power ratio (ΔCPR) for the Lungmen Plant, which is a basis to determine the operating limit minimum critical power ratio value. The partial arc mode is adopted in Lungmen Plant to control the position of the turbine control valve. However, the transient analyses presented in the Lungmen Final Safety Analysis Report (FSAR) assume that the TCVs are in the full arc mode. In this study, the Lungmen RETRAM model with partial arc mode is used to analyze the SCVCF event to offer more realistic results than the FSAR. It is concluded that the most limiting maximum combined flow limiter (MCFL) setting in RETRAN analysis is different from that of FSAR. An optimum operating range for the MCFL is suggested to gain the margin against the operating drift. Additionally, a Heat Flux Factor index is defined to appropriately determine the ranking of these cases in terms of ΔCPR.

  15. Percutaneous closure of paravalvular leaks after transcatheter aortic valve implantation with Edwards SAPIEN prosthesis: a report of two cases.

    Science.gov (United States)

    Estévez-Loureiro, Rodrigo; Salgado-Fernández, Jorge; Vázquez-González, Nicolás

    2013-02-01

    Significant periprosthetic aortic regurgitation after transcatheter aortic valve implantation with Edwards SAPIEN prosthesis has become a major concern of this technique given its association with impaired survival. We report the successful closure of such defects using vascular occlusion devices with significant improvement in clinical status of patients.

  16. Virtual reality 3D echocardiography in the assessment of tricuspid valve function after surgical closure of ventricular septal defect

    NARCIS (Netherlands)

    G. Bol-Raap (Goris); A.H.J. Koning (Anton); T.V. Scohy (Thierry); A.D.J. ten Harkel (Arend); F.J. Meijboom (Folkert); A.P. Kappetein (Arie Pieter); P.J. van der Spek (Peter); A.J.J.C. Bogers (Ad)

    2007-01-01

    textabstractBackground. This study was done to investigate the potential additional role of virtual reality, using three-dimensional (3D) echocardiographic holograms, in the postoperative assessment of tricuspid valve function after surgical closure of ventricular septal defect (VSD). Methods. 12

  17. Some considerations on water-hammer and cavitation following the sudden closure of a check-valve

    International Nuclear Information System (INIS)

    Caumette, P.; Lott, M.

    1987-01-01

    The function of a no-return check-valve is to obturate a pipe when the current in it has a tendancy to revert: in normal operation the valve is maintained in open position by the flow and it closes, in case of flow-rate inversion, under the action of its own weight and of the hydrodynamic forces. At the precise time of closure, the stream most of the time is suddenly interrupted, which determines a water-hammer and the separation of a water column followed by other water-hammers. The authors analyze the movement of a swing check-valve before closure and the subsequent evolution of the fluid state

  18. Perforation of the right aortic valve cusp: complication of ventricular septal defect closure with a modified Rashkind umbrella.

    Science.gov (United States)

    Vogel, M; Rigby, M L; Shore, D

    1996-01-01

    An 18-month-old boy with a perimembranous ventricular septal defect (VSD) had undergone transcatheter closure of the defect with a modified 17 mm Rashkind umbrella device at age 4 months (weight 3.8 kg). The clinical signs of a VSD persisted, and he developed aortic incompetence, first detected 5 months after the procedure, which progressed from mild to moderate. A three-dimensional echocardiographic study demonstrated that one of the four arms holding the umbrella was protruding into the aortic valve and had perforated the right aortic valve cusp. This diagnosis was confirmed at subsequent surgery. Surgical repair of the perforated right aortic valve leaflet was necessary. The umbrella was adherent to the tricuspid valve and could not be removed. Instead it was left in situ, but three of the stainless steel arms were cut off. When umbrella closure of a perimembranous VSD is undertaken, the close proximity of part of the distal umbrella to the aortic valve can lead to aortic regurgitation.

  19. Percutaneous Closure of 2 Paravalvular Leaks and a Gerbode Defect after Mitral Valve Replacement for Infective Endocarditis.

    Science.gov (United States)

    Peñalver, Jorge; Shatila, Wassim; Silva, Guilherme V

    2017-04-01

    Surgical valve replacement after infective endocarditis can result in local destructive paravalvular lesions. A 30-year-old woman with infective endocarditis underwent mitral valve replacement that was complicated postoperatively by 2 paravalvular leaks. During percutaneous closure of the leaks, a Gerbode defect was also found and closed. We discuss our patient's case and its relation to others in the relevant medical literature. To our knowledge, we are the first to describe the use of a percutaneous approach to close concomitant paravalvular leaks and a Gerbode defect.

  20. Anticipated transient without scram analysis of the simplified boiling water reactor following main steam isolation valve closure with boron injection

    International Nuclear Information System (INIS)

    Khan, H.J.; Cheng, H.S.; Rohatgi, U.S.

    1996-01-01

    The simplified boiling water reactor (SBWR) operating in natural circulation is designed with many passive safety features. An anticipated transient without scram (ATWS) initiated by inadvertent closure of the main steam isolation valve (MSIV) in an SBWR has been analyzed using the RAMONA-4B code of Brookhaven National Laboratory. This analysis demonstrates the predicted performance of the SBWR during an MSIV closure ATWS, followed by shutdown of the reactor through injection of boron into the reactor core from the standby liquid control system

  1. Analysis of a main steam isolation valve closure anticipated transient without scram in a boiling water reactor

    International Nuclear Information System (INIS)

    Liaw, T.J.; Pan, C.; Chen, G.S.

    1989-01-01

    Anticipated transient without scram (ATWS) could be a major accident sequence with possible core melt and containment damage in a boiling water reactor (BWR). The behavior of a BWR/6 during a main stream isolation valve closure ATWS is investigated using the best-estimate computer program, RETRAN-02. The effects of both makeup coolant and boron injection on the reactor behavior are studied. It is found that the BWR/6 behaves similarly to the BWR/2 and BWR/4

  2. Mechanism of Microbubble Growth at Mitral Mechanical Heart Valve (MHV) Closure

    Science.gov (United States)

    Rambod, Edmond; Beizaie, Masoud; Shusser, Michael; Gharib, Morteza

    1999-11-01

    The growth mechanism of microbubbles at mitral MHV closure has been experimentally studied. In the heart, some of the tiny bubbles grow explosively and form larger and persistent bubbles. An experimental set-up was designed to allow the passage of micron-size bubbles through an 80 micron-wide slot, simulating a typical gap between the housing ring and the occluders in MHV. The bubbles were generated using an air-liquid dispenser and were delivered to the system via a 250 micron-diameter hypedermic needle positioned vertically near the slot. A solenoid valve was used to deliver a 10cc volume of liquid in 25ms time through the slot. High-speed imaging was used to study the impact of flow through the slot on bubble growth. The velocity of liquid through the slot was assessed to be in the range of 12-15 m/s. Our observations confirmed the rapid and drastic growth of microbubbles following their passage through the narrow slot, due to pressure drop. Vortices, which were induced by flow separation on the downstream of the slot, caused the grown bubbles to shatter and form more stable bubbles.

  3. Independent deterministic analysis of the operational event with turbine valve closure and one atmospheric dump valve stuck open

    International Nuclear Information System (INIS)

    Rijova, N.

    2007-01-01

    The paper presents the results of the independent analysis of the operational event which took place on 07.11.2003 at Unit 1 of Rostov NPP. The event started with switching off the electrical generator of the turbine due to a short cut at the local switching substation. The turbine isolating valves closed to prevent damage of the turbine. The condenser dump valves (BRU-K) and the atmospheric dump valves (BRU-A) opened to release the vapour generated in the steam generators. After the pressure decrease in the steam generators BRU-K and BRU-A closed but one valve stuck opened. The emergency core cooling system was activated automatically. The main circulation pump of the loop corresponding to the steam generator with the stuck BRU-A was tripped. The stuck valve was closed by the operational stuff manually. No safety limits were violated. The analysis of the event was carried out using ATHLET code. A reasonable agreement was achieved between the calculated and measured values. (author)

  4. Virtual reality 3D echocardiography in the assessment of tricuspid valve function after surgical closure of ventricular septal defect

    Directory of Open Access Journals (Sweden)

    Kappetein A Pieter

    2007-02-01

    Full Text Available Abstract Background This study was done to investigate the potential additional role of virtual reality, using three-dimensional (3D echocardiographic holograms, in the postoperative assessment of tricuspid valve function after surgical closure of ventricular septal defect (VSD. Methods 12 data sets from intraoperative epicardial echocardiographic studies in 5 operations (patient age at operation 3 weeks to 4 years and bodyweight at operation 3.8 to 17.2 kg after surgical closure of VSD were included in the study. The data sets were analysed as two-dimensional (2D images on the screen of the ultrasound system as well as holograms in an I-space virtual reality (VR system. The 2D images were assessed for tricuspid valve function. In the I-Space, a 6 degrees-of-freedom controller was used to create the necessary projectory positions and cutting planes in the hologram. The holograms were used for additional assessment of tricuspid valve leaflet mobility. Results All data sets could be used for 2D as well as holographic analysis. In all data sets the area of interest could be identified. The 2D analysis showed no tricuspid valve stenosis or regurgitation. Leaflet mobility was considered normal. In the virtual reality of the I-Space, all data sets allowed to assess the tricuspid leaflet level in a single holographic representation. In 3 holograms the septal leaflet showed restricted mobility that was not appreciated in the 2D echocardiogram. In 4 data sets the posterior leaflet and the tricuspid papillary apparatus were not completely included. Conclusion This report shows that dynamic holographic imaging of intraoperative postoperative echocardiographic data regarding tricuspid valve function after VSD closure is feasible. Holographic analysis allows for additional tricuspid valve leaflet mobility analysis. The large size of the probe, in relation to small size of the patient, may preclude a complete data set. At the moment the requirement of an I

  5. Transient severe left ventricular dysfunction following percutaneous patent ductus arteriosus closure in an adult with bicuspid aortic valve: A case report.

    Science.gov (United States)

    Hwang, Hui-Jeong; Yoon, Kyung Lim; Sohn, Il Suk

    2016-03-01

    The present study reported the case of a 60-year-old female with patent ductus arteriosus (PDA) and a bicuspid aortic valve, who presented with transient severe left ventricular (LV) dysfunction following percutaneous closure of PDA, as identified by speckle tracking analysis. Transient LV dysfunction following PDA closure has previously been reported; however, severe LV dysfunction is rare. In the present case, the combination of a large PDA size, large amount of shunting, LV remodeling and bicuspid aortic valve may have induced serious deterioration of LV function following PDA closure. Furthermore, speckle-tracking echocardiography may be useful in the estimation of functional alterations in the myocardium of the LV following PDA closure. The observations detailed in the present study may improve the understanding of the pathophysiology and myocardial patterns of transient left ventricular dysfunction following PDA closure in adult humans.

  6. A Study of System Pressure Transients Generated by Isolation Valve Open/Closure in Orifice Manifold

    Energy Technology Data Exchange (ETDEWEB)

    Kim, M. [KEPCO, Daejeon (Korea, Republic of); Bae, S. W.; Kim, J. I.; Park, S. J. [KHNP, Abu Dhabi (United Arab Emirates)

    2016-05-15

    In this study, we explore the effects of pressure transients on peak and minimal pressures caused by the actuation of isolation valve and control valve reacting to the combined orifice operation of orifice manifold with motor-operated valve installed in the rear of the orifice. We then use the collected data to direct our effort towards cause analysis and propose improvements to efficiency and safety of operation. This formation is used to by domestic and foreign nuclear power plants as a mean to control flow rate, producing required flow rate jointly together by combination of the orifices. No significant impacts on the internals of manifold orifice due to peak pressure has been observed, although chance of cavitation at the outlet of control valve is significant. Considering the peak pressure, as well as minimum pressure occurs in low flow rate conditions, the pressure transient is more so affected by the characteristics (modified equal percentage) of control valve. Isolation valve of the orifice and control valve operate organically, therefore stroke time for valves need to be applied in order for both valves to cooperatively formulate an optimized operation.

  7. Transient severe left ventricular dysfunction following percutaneous patent ductus arteriosus closure in an adult with bicuspid aortic valve: A case report

    OpenAIRE

    HWANG, HUI-JEONG; YOON, KYUNG LIM; SOHN, IL SUK

    2016-01-01

    The present study reported the case of a 60-year-old female with patent ductus arteriosus (PDA) and a bicuspid aortic valve, who presented with transient severe left ventricular (LV) dysfunction following percutaneous closure of PDA, as identified by speckle tracking analysis. Transient LV dysfunction following PDA closure has previously been reported; however, severe LV dysfunction is rare. In the present case, the combination of a large PDA size, large amount of shunting, LV remodeling and ...

  8. Surgical repair of tricuspid valve leaflet tear following percutaneous closure of perimembranous ventricular septal defect using Amplatzer duct occluder I: Report of two cases

    Directory of Open Access Journals (Sweden)

    Saatchi Mahesh Kuwelker

    2017-01-01

    Full Text Available Tricuspid valve (TV injury following transcatheter closure of perimembranous ventricular septal defect (PMVSD with Amplatzer ductal occluder I (ADO I, requiring surgical repair, is rare. We report two cases of TV tear involving the anterior and septal leaflets following PMVSD closure using ADO I. In both the patients, the subvalvular apparatus remained unaffected. The patients presented with severe tricuspid regurgitation (TR 6 weeks and 3 months following the device closure. They underwent surgical repair with patch augmentation of the TV leaflets. Postoperatively, both are asymptomatic with a mild residual TR.

  9. 49 CFR Appendix A to Part 180 - Internal Self-closing Stop Valve Emergency Closure Test for Liquefied Compressed Gases

    Science.gov (United States)

    2010-10-01

    ... internal self-closing stop valve's lever, piston, or other valve indicator has moved to the closed position. 2. On pump-actuated pressure differential internal valves, the three-way toggle valve handle or its...

  10. Catheter Ablation of Atrial Fibrillation in Patients with Hardware in the Heart - Septal Closure Devices, Mechanical Valves and More.

    Science.gov (United States)

    Bartoletti, Stefano; Santangeli, Pasquale; DI Biase, Luigi; Natale, Andrea

    2013-01-01

    Patients with mechanical "hardware" in the heart, such as those with mechanical cardiac valves or atrial septal closure devices, represent a population at high risk of developing AF. Catheter ablation of AF in these subjects might represent a challenge, due to the perceived higher risk of complications associated with the presence of intracardiac mechanical devices. Accordingly, such patients were excluded or poorly represented in major trials proving the benefit of catheter ablation for the rhythm-control of AF. However, recent evidence supports the concept that catheter ablation procedures might be equally effective in these patients, without a significant increase in the risk of procedural complications. This review will summarize the current state-of-the-art on catheter ablation of AF in patients with mechanical "hardware" in the heart.

  11. Simulation of a chain of collapsible contracting lymphangions with progressive valve closure.

    Science.gov (United States)

    Bertram, C D; Macaskill, C; Moore, J E

    2011-01-01

    The aim of this investigation was to achieve the first step toward a comprehensive model of the lymphatic system. A numerical model has been constructed of a lymphatic vessel, consisting of a short series chain of contractile segments (lymphangions) and of intersegmental valves. The changing diameter of a segment governs the difference between the flows through inlet and outlet valves and is itself governed by a balance between transmural pressure and passive and active wall properties. The compliance of segments is maximal at intermediate diameters and decreases when the segments are subject to greatly positive or negative transmural pressure. Fluid flow is the result of time-varying active contraction causing diameter to reduce and is limited by segmental viscous and valvular resistance. The valves effect a smooth transition from low forward-flow resistance to high backflow resistance. Contraction occurs sequentially in successive lymphangions in the forward-flow direction. The behavior of chains of one to five lymphangions was investigated by means of pump function curves, with variation of valve opening parameters, maximum contractility, lymphangion size gradation, number of lymphangions, and phase delay between adjacent lymphangion contractions. The model was reasonably robust numerically, with mean flow-rate generally reducing as adverse pressure was increased. Sequential contraction was found to be much more efficient than synchronized contraction. At the highest adverse pressures, pumping failed by one of two mechanisms, depending on parameter settings: either mean leakback flow exceeded forward pumping or contraction failed to open the lymphangion outlet valve. Maximum pressure and maximum flow-rate were both sensitive to the contractile state; maximum pressure was also determined by the number of lymphangions in series. Maximum flow-rate was highly sensitive to the transmural pressure experienced by the most upstream lymphangions, suggesting that many

  12. Diastolic mitral and tricuspid regurgitation by Doppler echocardiography in patients with atrioventricular block: new insight into the mechanism of atrioventricular valve closure.

    Science.gov (United States)

    Schnittger, I; Appleton, C P; Hatle, L K; Popp, R L

    1988-01-01

    The purpose of this study was to prospectively determine the incidence of diastolic mitral and tricuspid regurgitation in atrioventricular (AV) block using Doppler echocardiography. The temporal relation between mitral and tricuspid diastolic insufficiency and the diastolic murmur recorded in patients with complete heart block was also investigated. Twenty-two consecutive patients with AV block (referred to the Echo-Doppler laboratory for routine clinical studies), aged 18 to 87 years, were enrolled in the study. Eleven patients had third degree AV block and a ventricular-inhibited (VVI) pacemaker, two patients had second degree AV block, seven patients had first degree AV block, one patient had blocked premature atrial complexes and one patient had atrial flutter with 4:1 AV block. Diastolic mitral regurgitation was detected in 20 patients, and diastolic tricuspid regurgitation in 21. A mid-diastolic murmur was detected in all patients except in the three youngest. The murmur occurred before diastolic regurgitation and coincided with peak forward flow through the AV valve after atrial contraction. M-mode mitral valve echocardiograms obtained in nine patients demonstrated near closure of some portions of the mitral valve after atrial contraction. Effective closure of the valve, however, did not occur unless ventricular systole supervened. In conclusion, diastolic mitral and tricuspid regurgitation are almost universally present in patients with AV block and are associated with a diastolic murmur. The murmur coincides with forward AV valve flow. Diastolic regurgitation is silent. Effective AV valve closure is not established until ventricular systole occurs, as demonstrated by M-mode echocardiographic recording of the mitral valve.

  13. The Fate of the Tricuspid Valve Following the Transatrial Closure of the Ventricular Septal Defect.

    Science.gov (United States)

    Giordano, Raffaele; Cantinotti, Massimiliano; Di Tommaso, Luigi; Comentale, Giuseppe; Tozzi, Andrea; Pilato, Emanuele; Iannelli, Gabriele; Palma, Gaetano

    2018-05-17

    The transatrial repair of the ventricular septal defect (VSD) requires an adequate exposure of its rim. We retrospectively evaluated the impact of adopting the tricuspid valve incision (TVI) technique, either with detachment or radial incision, on the postoperative outcome of children undergoing surgical VSD repair. From January 2008 to September 2017 we retrospectively enrolled 141 patients, divided into two groups: 97 patients were subjected to TVI (68.8%) and 44 patients (31.2%) were not subjected to TVI. All patients received an echocardiogram upon discharge from the hospital and after 1 month, 3 months, 6 months and a year from the treatment. No perioperative or late deaths resulted in our dataset. TVI was associated with a slightly longer cardio-pulmonary bypass and cross-clamp time but there were no differences in the surgical outcome between the two groups. Moreover, no differences occurred concerning residual VSD, atrioventricular block or tricuspid regurgitation at discharge. Echocardiograms at follow-up were available for 134 patients (95%) with a median of 5.3 years (range 0.5-9.3) and the degree of tricuspid regurgitation did not differ between groups. No patient required reoperation for tricuspid regurgitation or residual interventricular shunt. Finally, no difference was found even when comparing the two TVI subgroups. TVI should be used whenever intraoperative exposure of VSD is compromised in order to avoid a residual shunt and atrioventricular block. Here we show that this procedure does not significantly compromise the tricuspid function although a large, multicenter, randomized controlled trial is advised to validate this hypothesis. Copyright © 2018. Published by Elsevier Inc.

  14. Top closure for control rod drive for nuclear reactor

    International Nuclear Information System (INIS)

    Raas, J.H.; Schwartz, J.I.

    1978-01-01

    A removable top closure and venting assembly for the tubular housing of a control rod drive includes a mounting ring threadably inserted in the upper end of the housing, a fluid-sealing closure member beneath the mounting ring and which is mounted in and coupled to the mounting ring by means of a ball and socket joint, a gas vent defined by interconnecting passages extending through the closure and through the ball and socket joint, and a vent valve accessible from the top of the closure assembly. 3 claims, 2 figures

  15. Check valve

    Science.gov (United States)

    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.

  16. Check valve

    International Nuclear Information System (INIS)

    Upton, H.A.; Garcia, P.

    1999-01-01

    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

  17. Analysis of water hammer in a penstock in the case of valve closure. Part 2: Pressure losses concentrated downstream

    Directory of Open Access Journals (Sweden)

    Hocine HAMMOUM

    2017-06-01

    Full Text Available In our previous study (Part 1; by using the graphic of Bergeron, we have drawn the relationships which allow calculating flows and pressures at the valve and the reservoir, considering that pressure losses are negligible. Now, we assume in this second contribution that these pressure losses are concentrated downstream of the pipe, just at the entry of the valve. The study will focus on water hammer-induced by a slow closing of the valve. A practical example will be presented at the end of this work in order to illustrate the exposed method.

  18. Detection of a regulating valve closure failure during review of recorded data after an automatic reactor shut down. Incident at the NPP Beznau-1, 27 April 1995

    International Nuclear Information System (INIS)

    Deutschmann, H.

    1996-01-01

    After recognizing a leak in the oil system of the running main feedwater pump 1 during rated power operation of the plant the operator changed feedwater supply manually to the stand-by pump 2. A short time later pump 2 was automatically tripped by the signal ''low oil pressure''. Immediate reduction of the reactor power by the operator was not successful because the scram signal ''low steam generator level and mismatch of steam/feedwater flow'' occurred and scram was actuated. In this plant a special operating feature, actuated by the scram signal, is implemented to reduce steam release to atmosphere in case of scram. The signal ''scram and average primary Temperature >287 deg. C opens the feedwater regulating valves, and later, if the average primary temperature decreases to <287 deg. C, they reclose by a redundant signal. In the experienced event, after the scram actuation, in the steam generator A a feedwater overfill occurred. The overfill protection tripped the operating feedwater pumps (main feedwater pump 3 and two auxiliary feedwater pumps). The large injection of water produced an overcooling of the primary with isolation of the volume control system outlet of the primary. The operator repaired the defective oil coolers of the feedwater pumps and restarted the plant. At that time, he had not recognized, that the plant response, which caused the steam generator overfill, was wrong. One day later, as all the recorded data were reviewed in more detail, it was found that the closure time of the feedwater regulating valve to steam generator A was much longer than designed (19 s instead 7 s). The operator requested an LCO for continued operation in spite of the fact, that the closure time was not fixed in the Technical specification. 3 figs

  19. Analysis of water hammer in a penstock in the case of valve closure. Part 1: Without pressure losses

    Directory of Open Access Journals (Sweden)

    Hocine HAMMOUM

    2016-04-01

    Full Text Available We develop, in this paper, a method of calculating the water hammer inspired by the graphic construction of Bergeron, which we qualify as analytical method. In helping us of these graphs, we get the relationships that allow calculating the flow rates and pressures along a penstock. The flow of water is carried out by gravity adduction connecting at upstream a storage tank and at downstream a valve. In this first part, we neglect the pressure losses. The study will focus on water hammer-induced by a slow closing of the valve. A practical example will be presented at the end of this work in order to illustrate the exposed method.

  20. Tubular closure device

    International Nuclear Information System (INIS)

    Klahn, F.C.; Nolan, J.H.; Wills, C.

    1982-01-01

    This invention relates to a closure mechanism for closing openings such as the bore of a conduit and for releasably securing members within the bore. More particularly, this invention relates to a closure mechanism for tubular irradiation surveillance specimen assembly holders used in nuclear reactors

  1. Tubular closure mechanism

    International Nuclear Information System (INIS)

    Kalen, D.D.; Mitchem, J.W.

    1982-01-01

    This invention relates to a closure mechanism for tubular irradiation surveillance specimen assembly holder used in nuclear reactors. The closure mechanism is composed of a latching member which includes a generally circular chamber with a plurality of elongated latches depending therefrom. The latching member circumscribes part of an actuator member which is disposed within the latching member so as to be axially movable. The axial movement of the actuator actuates positioning of the latches between positions in which the latches are locked and secured within the actuator member. Means, capable of being remotely manipulated, are provided to move the actuator in order to position the latches and load the articles within the tube

  2. Water hammer and column separation due to accidental simultaneous closure of control valves in a large scale two-phase flow experimental test rig

    NARCIS (Netherlands)

    Bergant, A.; Westende, van 't J.M.C.; Koppel, T.; Gale, J.; Hou, Q.; Pandula, Z.; Tijsseling, A.S.

    2010-01-01

    A large-scale pipeline test rig at Deltares, Delft, The Netherlands has been used for filling and emptying experiments. Tests have been conducted in a horizontal 250 mm diameter PVC pipe of 258 m length with control valves at the downstream and upstream ends. This paper investigates the accidental

  3. Heart valve surgery

    Science.gov (United States)

    ... replacement; Valve repair; Heart valve prosthesis; Mechanical valves; Prosthetic valves ... surgery. Your heart valve has been damaged by infection ( endocarditis ). You have received a new heart valve ...

  4. Road Closures

    Data.gov (United States)

    Montgomery County of Maryland — This is an up to date map of current road closures in Montgomery County.This dataset is updated every few minutes from the Department of Transportation road closure...

  5. Valve Disease

    Science.gov (United States)

    ... blood. There are 4 valves in the heart: tricuspid, pulmonary, mitral, and aortic. Two types of problems can disrupt blood flow through the valves: regurgitation or stenosis. Regurgitation is also called insufficiency or incompetence. Regurgitation happens when a valve doesn’ ...

  6. Nuclear reactor steam depressurization valve

    International Nuclear Information System (INIS)

    Moore, G.L.

    1991-01-01

    This patent describes improvement in a nuclear reactor plant, an improved steam depressurization valve positioned intermediate along a steam discharge pipe for controlling the venting of steam pressure from the reactor through the pipe. The improvement comprises: a housing including a domed cover forming a chamber and having a partition plate dividing the chamber into a fluid pressure activation compartment and a steam flow control compartment, the valve housing being provided with an inlet connection and an outlet connection in the steam flow control compartment, and a fluid duct in communication with a source of fluid pressure for operating the valve; a valve set mounted within the fluid flow control compartment comprising a cylindrical section surrounding the inlet connection with one end adjoining the connection and having a radially projecting flange at the other end with a contoured extended valve sealing flange provided with an annular valve sealing member, and a valve cylinder traversing the partition plate and reciprocally movable within an opening in the partition plate with one terminal and extending into the fluid pressure activation compartment and the other terminal end extending into the steam flow control compartment coaxially aligned with the valve seat surrounding the inlet connection, the valve cylinder being surrounded by two bellow fluid seals and provided with guides to inhibit lateral movement, an end of the valve cylinder extending into the fluid flow control compartment having a radially projecting flange substantially conterminous with the valve seat flange and having a contoured surface facing and complimentary to the contoured valve seating surface whereby the two contoured valve surfaces can meet in matching relationship, thus providing a pressure actuated reciprocatable valve member for making closing contact with the valve seat and withdrawing therefrom for opening fluid flow through the valve

  7. Tight valve

    International Nuclear Information System (INIS)

    Guedj, F.

    1987-01-01

    This sealed valve is made with a valve seat, an axial valve with a rod fixed to its upper end, a thick bell surrounding the rod and welded by a thin join on the valve casing, a threated ring screwed onto the upper end of the rod and a magnet or electromagnet rotating the ring outside the bell [fr

  8. Resting multilayer 2D speckle-tracking TTE for detection of ischemic segments confirmed by invasive FFR part-2, using post-systolic-strain-index and time from aortic-valve-closure to regional peak longitudinal-strain.

    Science.gov (United States)

    Ozawa, Koya; Funabashi, Nobusada; Nishi, Takeshi; Takahara, Masayuki; Fujimoto, Yoshihide; Kamata, Tomoko; Kobayashi, Yoshio

    2016-08-15

    This study evaluated the post-systolic strain index (PSI), and the time interval between aortic valve closure (AVC) and regional peak longitudinal strain (PLS), measured by transthoracic echocardiography (TTE), for detection of left ventricular (LV) myocardial ischemic segments confirmed by invasive fractional flow reserve (FFR). 39 stable patients (32 males; 65.8±11.9years) with 46 coronary arteries at ≥50% stenosis on invasive coronary angiography underwent 2D speckle tracking TTE (Vivid E9, GE Healthcare) and invasive FFR measurements. PSI, AVC and regional PLS in each LV segment were calculated. FFR ≤0.80 was detected in 27 LV segments. There were no significant differences between segments supplied by FFR ≤0.80 and FFR >0.80 vessels in either PSI or the time interval between AVC and regional PLS. To identify LV segments±FFR ≤0.80, the receiver operator characteristic (ROC) curves for PSI, and the time interval between AVC and regional PLS had areas under the curve (AUC) values of 0.58 and 0.57, respectively, with best cut-off points of 12% (sensitivity 70.4%, specificity 57.9%) and 88ms (sensitivity 70.4%, specificity 52.6%), respectively, but the AUCs were not statistically significant. In stable coronary artery disease patients with ≥50% coronary artery stenosis, measurement of PSI, and the time interval between AVC and regional PLS, on resting TTE, enabled the identification of LV segments with FFR ≤0.80 using each appropriate threshold for PSI, and the time interval between AVC and regional PLS, with reasonable diagnostic accuracy. However, the AUC values were not statistically significant. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

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

    Science.gov (United States)

    DeWall, Kevin George [Pocatello, ID; Garcia, Humberto Enrique [Idaho Falls, ID; McKellar, Michael George [Idaho Falls, ID

    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.

  10. Closure requirements

    International Nuclear Information System (INIS)

    Hutchinson, I.P.G.; Ellison, R.D.

    1992-01-01

    Closure of a waste management unit can be either permanent or temporary. Permanent closure may be due to: economic factors which make it uneconomical to mine the remaining minerals; depletion of mineral resources; physical site constraints that preclude further mining and beneficiation; environmental, regulatory or other requirements that make it uneconomical to continue to develop the resources. Temporary closure can occur for a period of several months to several years, and may be caused by factors such as: periods of high rainfall or snowfall which prevent mining and waste disposal; economic circumstances which temporarily make it uneconomical to mine the target mineral; labor problems requiring a cessation of operations for a period of time; construction activities that are required to upgrade project components such as the process facilities and waste management units; and mine or process plant failures that require extensive repairs. Permanent closure of a mine waste management unit involves the provision of durable surface containment features to protect the waters of the State in the long-term. Temporary closure may involve activities that range from ongoing maintenance of the existing facilities to the installation of several permanent closure features in order to reduce ongoing maintenance. This paper deals with the permanent closure features

  11. Control Valve

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Wayne R.

    2018-03-20

    A control valve includes a first conduit having a first inlet and a first outlet and defining a first passage; a second conduit having a second inlet and a second outlet and defining a second passage, the second conduit extending into the first passage such that the second inlet is located within the first passage; and a valve plate disposed pivotably within the first passage, the valve plate defining a valve plate surface. Pivoting of the valve plate within the first passage varies flow from the first inlet to the first outlet and the valve plate is pivotal between a first position and a second position such that in the first position the valve plate substantially prevents fluid communication between the first passage and the second passage and such that in the second position the valve plate permits fluid communication between the first passage and the second passage.

  12. Valve assembly

    International Nuclear Information System (INIS)

    Sandling, M.

    1981-01-01

    An improved valve assembly, used for controlling the flow of radioactive slurry, is described. Radioactive contamination of the air during removal or replacement of the valve is prevented by sucking air from the atmosphere through a portion of the structure above the valve housing. (U.K.)

  13. Double-reed exhaust valve engine

    Science.gov (United States)

    Bennett, Charles L.

    2015-06-30

    An engine based on a reciprocating piston engine that extracts work from pressurized working fluid. The engine includes a double reed outlet valve for controlling the flow of low-pressure working fluid out of the engine. The double reed provides a stronger force resisting closure of the outlet valve than the force tending to open the outlet valve. The double reed valve enables engine operation at relatively higher torque and lower efficiency at low speed, with lower torque, but higher efficiency at high speed.

  14. Double-disc gate valve

    International Nuclear Information System (INIS)

    Wheatley, S.J.

    1979-01-01

    The invention relates to an improvement in a conventional double-disc gate valve having a vertically movable gate assembly including a wedge, spreaders slidably engaged therewith, 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 separation 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

  15. Improved valve and dash-pot assembly

    Science.gov (United States)

    Chang, S.C.

    1985-04-23

    A dash-pot valve comprises a cylinder submerged in the fluid of a housing and have a piston attached to a plunger projecting into the path of closing movement of a pivotal valve member. A vortex chamber in said cylinder is provided with targentially directed inlets to generate vortex flow upon retraction of said plunger and effect increasing resistance against said piston to progressively retard the closing rate of said valve member toward its seat.

  16. Valve and dash-pot assembly

    Science.gov (United States)

    Chang, Shih-Chih

    1986-01-01

    A dash-pot valve comprising a cylinder submerged in the fluid of a housing and having a piston attached to a plunger projecting into the path of closing movement of a pivotal valve member. A vortex chamber in said cylinder is provided with tangentially directed inlets to generate vortex flow upon retraction of said plunger and effect increasing resistance against said piston to progressively retard the closing rate of said valve member toward its seat.

  17. Vertical pump with free floating check valve

    International Nuclear Information System (INIS)

    Lindsay, M.

    1980-01-01

    A vertical pump is described which has a bottom discharge with a free floating check valve disposed in the outlet plenum thereof. The free floating check valve comprises a spherical member with a hemispherical cage-like member attached thereto which is capable of allowing forward or reverse flow under appropriate conditions while preventing reverse flow under inappropriate conditions

  18. Mitral Valve Disease

    Science.gov (United States)

    ... for mitral valve replacement—mechanical valves (metal) or biological valves (tissue). The principal advantage of mechanical valves ... small risk of stroke due to blood clotting. Biological valves usually are made from animal tissue. Biological ...

  19. Traumatic Mitral Valve and Pericardial Injury

    Directory of Open Access Journals (Sweden)

    Nissar Shaikh

    2013-01-01

    Full Text Available Cardiac injury after blunt trauma is common but underreported. Common cardiac trauma after the blunt chest injury (BCI is cardiac contusion; it is very rare to have cardiac valve injury. The mitral valve injury during chest trauma occurs when extreme pressure is applied at early systole during the isovolumic contraction between the closure of the mitral valve and the opening of the aortic valve. Traumatic mitral valve injury can involve valve leaflet, chordae tendineae, or papillary muscles. For the diagnosis of mitral valve injury, a high index of suspicion is required, as in polytrauma patients, other obvious severe injuries will divert the attention of the treating physician. Clinical picture of patients with mitral valve injury may vary from none to cardiogenic shock. The echocardiogram is the main diagnostic modality of mitral valve injuries. Patient’s clinical condition will dictate the timing and type of surgery or medical therapy. We report a case of mitral valve and pericardial injury in a polytrauma patient, successfully treated in our intensive care unit.

  20. Valve testing for UK PWR safety applications

    International Nuclear Information System (INIS)

    George, P.T.; Bryant, S.

    1989-01-01

    Extensive testing and development has been done by the Central Electricity Generating Board (CEGB) to support the design, construction and operation of Sizewell B, the UK's first PWR. A Blowdown Rig for the Assessment of Valve Operability - (BRAVO) has been constructed at the CEGB Marchwood Engineering Laboratory to reproduce PWR Pressurizer fluid conditions for the full scale testing of Pressurizer Relief System (PRS) valves. A full size tandem pair of Pilot Operated Safety Relief Valves (POSRVs) is being tested under the full range of pressurizer fluid conditions. Tests to date have produced important data on the performance of the valve in its Cold Overpressure protection mode of operation and on methods for the in-service testing of the valve. Also, a full size pressurizer safety valve has been tested under full PRS fluid conditions to develop a methodology for the pre-service testing of the Sizewell valves. Further work will be carried out to develop procedures for the in-service testing of the valve. In the Main Steam Safety Valve test program carried out at the Siemens-KWU Test Facilities, a single MSSV from three potential suppliers was tested under full secondary system conditions. The test results have been analyzed and are reflected in the CEGB's arrangements for the pre-service and in-service testing of the Sizewell MSSVs. Valves required to interrupt pipebreak flow must be qualified for this duty by testing or a combination of testing and analysis. To obtain guidance on the performance of such tests gate and globe valves have been subjected to simulated pipebreaks under PWR primary circuit conditions. In the light of problems encountered with gate valve closure under these conditions, further tests are currently being carried out on the BRAVO facility on a gate valve, in preparation for the full scale flow interruption qualification testing of the Sizewell main steam isolation valve

  1. Restaurant closures

    CERN Document Server

    Novae Restauration

    2012-01-01

    Christmas Restaurant closures Please note that the Restaurant 1 and Restaurant 3 will be closed from Friday, 21 December at 5 p.m. to Sunday, 6 January, inclusive. They will reopen on Monday, 7 January 2013.   Restaurant 2 closure for renovation To meet greater demand and to modernize its infrastructure, Restaurant 2 will be closed from Monday, 17 December. On Monday, 14 January 2013, Sophie Vuetaz’s team will welcome you to a renovated self-service area on the 1st floor. The selections on the ground floor will also be expanded to include pasta and pizza, as well as snacks to eat in or take away. To ensure a continuity of service, we suggest you take your break at Restaurant 1 or Restaurant 3 (Prévessin).

  2. Acoustic emission testing of piston check valves

    International Nuclear Information System (INIS)

    Stewart, D.L.

    1994-01-01

    Based on test experience at Comanche Peak Unit 1, an acoustic emission data evaluation matrix for piston check valves has been developed. The degradations represented in this matrix were selected based on Edwards piston check valve failure data reported in the Nuclear Plant Reliability Data System. Evidence to support this matrix was collected from site test data on a variety of valve types. Although still under refinement, the matrix provides three major attributes for closure verification, which have proven useful in developing test procedures for inservice testing and preventing unnecessary disassembly

  3. When operable patients become inoperable: conversion of a surgical aortic valve replacement into transcatheter aortic valve implantation

    DEFF Research Database (Denmark)

    Olsen, Lene Kjaer; Arendrup, Henrik; Engstrøm, Thomas

    2009-01-01

    . On extracorporal circulation it was reconized that the aortic annulus, the coronary ostiae and the proximal part of the ascending aorta were severely calcified making valve implantation impossible. Surgical closure without valve substitution was estimated to be associated with a high risk of mortality due...

  4. The effect of some hemodynamic factors on the behaviour of the aortic valve

    NARCIS (Netherlands)

    Steenhoven, van A.A.; Veenstra, P.C.; Reneman, R.S.

    1982-01-01

    To test the validity of a theoretical model of aortic valve closure, based upon the observations in a two-dimensional analogue, the effect of some hemodynamic factors on aortic valve behaviour was studied in open-chest dogs. Direct cinematography was used to record aortic valve movements. The ECG,

  5. Developing an optimal valve closing rule curve for real-time pressure control in pipes

    Energy Technology Data Exchange (ETDEWEB)

    Bazarganlari, Mohammad Reza; Afshar, Hossein [Islamic Azad University, Tehran (Iran, Islamic Republic of); Kerachian, Reza [University of Tehran, Tehran (Iran, Islamic Republic of); Bashiazghadi, Seyyed Nasser [Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)

    2013-01-15

    Sudden valve closure in pipeline systems can cause high pressures that may lead to serious damages. Using an optimal valve closing rule can play an important role in managing extreme pressures in sudden valve closure. In this paper, an optimal closing rule curve is developed using a multi-objective optimization model and Bayesian networks (BNs) for controlling water pressure in valve closure instead of traditional step functions or single linear functions. The method of characteristics is used to simulate transient flow caused by valve closure. Non-dominated sorting genetic algorithms-II is also used to develop a Pareto front among three objectives related to maximum and minimum water pressures, and the amount of water passes through the valve during the valve-closing process. Simulation and optimization processes are usually time-consuming, thus results of the optimization model are used for training the BN. The trained BN is capable of determining optimal real-time closing rules without running costly simulation and optimization models. To demonstrate its efficiency, the proposed methodology is applied to a reservoir-pipe-valve system and the optimal closing rule curve is calculated for the valve. The results of the linear and BN-based valve closure rules show that the latter can significantly reduce the range of variations in water hammer pressures.

  6. Are anticoagulant independent mechanical valves within reach-fast prototype fabrication and in vitro testing of innovative bi-leaflet valve models.

    Science.gov (United States)

    Scotten, Lawrence N; Siegel, Rolland

    2015-08-01

    Exploration for causes of prosthetic valve thrombogenicity has frequently focused on forward or post-closure flow detail. In prior laboratory studies, we uncovered high amplitude flow velocities of short duration close to valve closure implying potential for substantial shear stress with subsequent initiation of blood coagulation pathways. This may be relevant to widely accepted clinical disparity between mechanical and tissue valves vis-à-vis thrombogenicity. With a series of prototype bi-leaflet mechanical valves, we attempt reduction of closure related velocities with the objective of identifying a prototype valve with thrombogenic potential similar to our tissue valve control. This iterative design approach may find application in preclinical assessment of valves for anticoagulation independence. Tested valves included: prototype mechanical bi-leaflet BVs (n=56), controls (n=2) and patented early prototype mechanicals (n=2) from other investigators. Pulsatile and quasi-steady flow systems were used for testing. Projected dynamic valve area (PDVA) was measured using previously described novel technology. Flow velocity over the open and closing periods was determined by volumetric flow rate/PDVA. For the closed valve interval, use was made of data obtained from quasi-steady back pressure/flow tests. Performance was ranked by a proposed thrombogenicity potential index (TPI) relative to tissue and mechanical control valves. Optimization of the prototype valve designs lead to a 3-D printed model (BV3D). For the mitral/aortic site, BV3D has lower TPI (1.10/1.47) relative to the control mechanical valve (3.44/3.93) and similar to the control tissue valve (ideal TPI ≤1.0). Using unique technology, rapid prototyping and thrombogenicity ranking, optimization of experimental valves for reduced thrombogenic potential was expedited and simplified. Innovative mechanical valve configurations were identified that merit consideration for further development which may bring

  7. Effect of the sinus of valsalva on the closing motion of bileaflet prosthetic heart valves.

    Science.gov (United States)

    Ohta, Y; Kikuta, Y; Shimooka, T; Mitamura, Y; Yuhta, T; Dohi, T

    2000-04-01

    Conventional bileaflet prosthetic mechanical heart valves close passively with backflow. Naturally, the valve has problems associated with closure, such as backflow, water hammer effect, and fracture of the leaflet. On the other hand, in the case of the natural aortic valve, the vortex flow in the sinus of Valsalva pushes the leaflet to close, and the valve starts the closing motion earlier than the prosthetic valve as the forward flow decelerates. This closing mechanism is thought to decrease backflow at valve closure. In this study, we propose a new bileaflet mechanical valve resembling a drawbridge in shape, and the prototype valve was designed so that the leaflet closes with the help of the vortex flow in the sinus. The test valve was made of aluminum alloy, and its closing motion was compared to that of the CarboMedics (CM) valve. Both valves were driven by a computer controlled hydraulic mock circulator and were photographed at 648 frames/s by a high speed charge-coupled device (CCD) camera. Each frame of the valve motion image was analyzed with a personal computer, and the opening angles were measured. The flow rate was set as 5.0 L/min. The system was pulsed with 70 bpm, and the systolic/diastolic ratio was 0.3. Glycerin water was used as the circulation fluid at room temperature, and polystyrene particles were used to visualize the streamline. The model of the sinus of Valsalva was made of transparent silicone rubber. As a result, high speed video analysis showed that the test valve started the closing motion 41 ms earlier than the CM valve, and streamline analysis showed that the test valve had a closing mechanism similar to the natural one with the effect of vortex flow. The structure of the test valve was thought to be effective for soft closure and could solve problems associated with closure.

  8. Piezoelectric valve

    Science.gov (United States)

    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.

  9. Flow visualization of a monoleaflet and bileaflet mechanical heart valve in a pneumatic ventricular assist device using a PIV system.

    Science.gov (United States)

    Lee, Hwansung; Tatsumi, Eisuke; Taenaka, Yoshiyuki

    2010-01-01

    Our group is developing a new type of pulsatile pneumatic ventricular assist device (PVAD) that uses the Medtronic Hall tilting disc valve (M-H valve). Although tilting disc valves have good washout effect inside the blood pump, they are no longer in common clinical use and may be difficult to obtain in the future. To investigate the stability of the Sorin Bicarbon valve (S-B valve) in our PVAD, we constructed a model pump made of an acrylic resin with the same configuration as our PVAD and attempted to compare the flow visualization upstream and downstream of the outlet position valve between the M-H valve and the S-B valve using a particle image velocimetry (PIV) method. The outlet S-B valve had faster closure than the M-H valve. The maximum flow velocity was greater than with the M-H valve. The maximum Reynolds shear stress (RSS) of the M-H valve reached 150 N/m(2) and that of the S-B valve reached 300 N/m(2) upstream during the end-systolic and early-diastolic phases. In both valves, the maximum RSS upstream of the valve was higher than downstream of the valve because of the regurgitation flow during valve closure. In addition, the maximum viscous shear stress reached above 2 N/m(2), which occupied only about 1%-1.5% of the maximum RSS.

  10. Characterization of a bioprosthetic bicuspid venous valve hemodynamics: implications for mechanism of valve dynamics.

    Science.gov (United States)

    Tien, W-H; Chen, H Y; Berwick, Z C; Krieger, J; Chambers, S; Dabiri, D; Kassab, G S

    2014-10-01

    Chronic venous insufficiency (CVI) of the lower extremities is a common clinical problem. Although bioprosthetic valves have been proposed to treat severe reflux, clinical success has been limited due to thrombosis and neointima overgrowth of the leaflets that is, in part, related to the hemodynamics of the valve. A bioprosthetic valve that mimics native valve hemodynamics is essential. A computational model of the prosthetic valve based on realistic geometry and mechanical properties was developed to simulate the interaction of valve structure (fluid-structure interaction, FSI) with the surrounding flow. The simulation results were validated by experiments of a bioprosthetic bicuspid venous valve using particle image velocimetry (PIV) with high spatial and temporal resolution in a pulse duplicator (PD). Flow velocity fields surrounding the valve leaflets were calculated from PIV measurements and comparisons to the FSI simulation results were made. Both the spatial and temporal results of the simulations and experiments were in agreement. The FSI prediction of the transition point from equilibrium phase to valve-closing phase had a 7% delay compared to the PD measurements, while the PIV measurements matched the PD exactly. FSI predictions of reversed flow were within 10% compared to PD measurements. Stagnation or stasis regions were observed in both simulations and experiments. The pressure differential across the valve and associated forces on the leaflets from simulations showed the valve mechanism to be pressure driven. The flow velocity simulations were highly consistent with the experimental results. The FSI simulation and force analysis showed that the valve closure mechanism is pressure driven under the test conditions. FSI simulation and PIV measurements demonstrated that the flow behind the leaflet was mostly stagnant and a potential source for thrombosis. The validated FSI simulations should enable future valve design optimizations that are needed for

  11. Effects of pressure and temperature on gate valve unwedging

    Energy Technology Data Exchange (ETDEWEB)

    Damerell, P.S.; Harrison, D.H.; Hayes, P.W.; Simons, J.W.; Walker, T.A.

    1996-12-01

    The stem thrust required to unwedge a gate valve is influenced by the pressure and temperature when the valve is closed and by the changes in these conditions between closure and opening. {open_quotes}Pressure locking{close_quotes} and {open_quotes}thermal binding{close_quotes} refer to situations where pressure and temperature effects cause the unwedging load to be much higher than normal. A model of these phenomena has been developed. Wedging (closure) is modeled as developing an {open_quotes}interference{close_quotes} between the disk and its seat rings in the valve. The effects of pressure and temperature are analyzed to determine the change in this disk-to-seat {open_quotes}interference{close_quotes}. Flexibilities, of the disk, body, stem and yoke strongly influence the unwedging thrust. Calculations and limited comparisons to data have been performed for a range of valve designs and scenarios. Pressure changes can increase the unwedging load when there is either a uniform pressure decrease, or a situation where the bonnet pressure exceeds the pressures in the adjacent piping. Temperature changes can increase the unwedging load when: (1) valve closure at elevated system temperature produces a delayed stem expansion, (2) a temperature increase after closure produces a bonnet pressure increase, or (3) a temperature change after closure produces an increase in the disk-to-seat {open_quotes}interference{close_quotes} or disk-to-seat friction.

  12. Effects of pressure and temperature on gate valve unwedging

    International Nuclear Information System (INIS)

    Damerell, P.S.; Harrison, D.H.; Hayes, P.W.; Simons, J.W.; Walker, T.A.

    1996-01-01

    The stem thrust required to unwedge a gate valve is influenced by the pressure and temperature when the valve is closed and by the changes in these conditions between closure and opening. open-quotes Pressure lockingclose quotes and open-quotes thermal bindingclose quotes refer to situations where pressure and temperature effects cause the unwedging load to be much higher than normal. A model of these phenomena has been developed. Wedging (closure) is modeled as developing an open-quotes interferenceclose quotes between the disk and its seat rings in the valve. The effects of pressure and temperature are analyzed to determine the change in this disk-to-seat open-quotes interferenceclose quotes. Flexibilities, of the disk, body, stem and yoke strongly influence the unwedging thrust. Calculations and limited comparisons to data have been performed for a range of valve designs and scenarios. Pressure changes can increase the unwedging load when there is either a uniform pressure decrease, or a situation where the bonnet pressure exceeds the pressures in the adjacent piping. Temperature changes can increase the unwedging load when: (1) valve closure at elevated system temperature produces a delayed stem expansion, (2) a temperature increase after closure produces a bonnet pressure increase, or (3) a temperature change after closure produces an increase in the disk-to-seat open-quotes interferenceclose quotes or disk-to-seat friction

  13. Procedures and techniques for closure of near surface disposal facilities for radioactive waste

    International Nuclear Information System (INIS)

    2001-12-01

    The overall objective of this report is to provide Member States with guidance on planning and implementation of closure of near surface disposal facilities for low and intermediate level radioactive waste. The specific objectives are to review closure concepts, requirements, and components of closure systems; to discuss issues and approaches to closure, including regulatory, economic, and technical aspects; and to present major examples of closure techniques used and/or considered by Member States. Some examples of closure experience from Member States are presented in the Appendix and were indexed separately

  14. Autocracy bias in informal groups under need for closure.

    Science.gov (United States)

    Pierro, Antonio; Mannetti, Lucia; De Grada, Eraldo; Livi, Stefano; Kruglanski, Arie W

    2003-03-01

    Two experiments investigated the tendency of groups with members under high (vs. low) need for cognitive closure to develop an autocratic leadership structure in which some members dominate the discussion, constitute the "hubs" of communication, and influence the group more than other members. The first experiment found that high (vs. low) need for closure groups, as assessed via dispositional measure of the need for closure, manifested greater asymmetry of conversational floor control, such that members with autocratic interactional style were more conversationally dominant and influential than less autocratic members. The second experiment manipulated the need for closure via time pressure and utilized a social network analysis. Consistent with expectation, groups under time pressure (vs. no pressure) showed a greater asymmetry of participation, of centrality, and of prestige among the group members, such that the more focal members were perceived to exert the greater influence over the groups' decisions.

  15. Aortic valve bypass

    DEFF Research Database (Denmark)

    Lund, Jens T; Jensen, Maiken Brit; Arendrup, Henrik

    2013-01-01

    In aortic valve bypass (AVB) a valve-containing conduit is connecting the apex of the left ventricle to the descending aorta. Candidates are patients with symptomatic aortic valve stenosis rejected for conventional aortic valve replacement (AVR) or transcatheter aortic valve implantation (TAVI). ...

  16. Tubular closure mechanism

    International Nuclear Information System (INIS)

    Kalen, D.D.; Mitchem, J.W.

    1981-01-01

    An apparatus is provided for closing the bore of a tube and releasably securing articles within the tube under longitudinal load. A latching member has a cylindrical section and several circumferentially-spaced elongated latches hanging down from one end of the cylinder. An elongated actuator has integral cam and spline and is partly located within the latch with the cam radially contacting the latches and the spline projecting into the circumferential spaces between the latches. The actuator is axially movable between a position in which the latches are locked to the tube walls and a position in which the latches are secured from contact with the tube walls. Means are provided for axially moving the actuator such that the cam positions the latches; and means are also provided for engaging the articles within the tube. The closure is particularly applicable to tubular irradiation surveillance specimen assembly holders used in reactors

  17. Early results of gate valve flow interruption blowdown tests

    International Nuclear Information System (INIS)

    DeWall, K.G.

    1988-01-01

    The preliminary results of the USNRC/INEL high-energy BWR line break flow interruption testing are presented. Two representative nuclear valve assemblies were cycled under design basis Reactor Water Cleanup pipe break conditions to provide input for the technical basis for resolving the Nuclear Regulatory Commission's Generic Issue 87. The effects of the blowdown hydraulic loadings on valve operability, especially valve closure stem forces, were studied. The blowdown tests showed that, given enough thrust, typical gate valves will close against the high flow resulting from a line break. The tests also showed that proper operator sizing depends on the correct identification of values for the sizing equation. Evidence exists that values used in the past may not be conservative for all valve applications. The tests showed that improper operator lock ring installation following test or maintenance can invalidate in-situ test results and prevent the valve from performing its design function. 2 refs., 12 figs., 2 tabs

  18. Exceptional closure of UNIQA office at CERN

    CERN Multimedia

    HR Department

    2009-01-01

    The UNIQA office at CERN will be closed from Wednesday 18 February to Friday 20 February due to painting work. During this closure, the Headquarters of UNIQA in Geneva will remain at the disposal of the members. See details https://cern.ch/chis/UNIQA_Offices.asp The CERN office will re-open on Monday 23 February according to the normal schedule. We apologise for any inconvenience caused by this closure.

  19. The iValve Hands-Free Speech Valve for Laryngectomized Patients. In Vitro Test of a Novel Device of Revolutionary Design

    NARCIS (Netherlands)

    van der Houwen, E. B.; van Kalkeren, T. A.; Burgerhof, J. G. M.; van der Laan, B. F. A. M.; Verkerke, G. J.; Jobbagy, A

    2012-01-01

    Background. Speech valves help restore speech after surgical removal of the larynx (laryngectomy). Laryngectomized Patients breathe through an artificial opening (tracheostoma) in the neck. A shunt valve is routinely inserted between oesophagus and trachea to restore speech. At closure of the stoma

  20. Transcatheter aortic valve replacement

    Science.gov (United States)

    ... gov/ency/article/007684.htm Transcatheter aortic valve replacement To use the sharing features on this page, please enable JavaScript. Transcatheter aortic valve replacement (TAVR) is surgery to replace the aortic valve. ...

  1. Magnetically operated check valve

    Science.gov (United States)

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

    1994-06-01

    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.

  2. Closure for milliliter scale bioreactor

    Science.gov (United States)

    Klein, David L.; Laidlaw, Robert D.; Andronaco, Gregory; Boyer, Stephen G.

    2010-12-14

    A closure for a microreactor includes a cap that is configured to be inserted into a well of the microreactor. The cap, or at least a portion of the cap, is compliant so as to form a seal with the well when the cap is inserted. The cap includes an aperture that provides an airway between the inside of the well to the external environment when the cap is inserted into the well. A porous plug is inserted in the aperture, e.g., either directly or in tube that extends through the aperture. The porous plug permits gas within the well to pass through the aperture while preventing liquids from passing through to reduce evaporation and preventing microbes from passing through to provide a sterile environment. A one-way valve may also be used to help control the environment in the well.

  3. All in the family: matrimonial mitral valve clicks.

    Science.gov (United States)

    Desser, K B; Bokhari, S I; Benchimol, A; Romney, D

    1981-05-01

    Mitral valve clicks with or without late systolic murmurs were detected in genetically unrelated marital partners of 5 families. The first family represented 2 successive nonconsanguineous marital unions with 3 generations of mitral valve clicks. The second family included 1 natural and 2 adopted children with clinical and echographic evidence of mitral valve prolapse. The third family was comprised of asymptomatic parents, both with nonejection clicks and mitral valve prolapse, whose daughter presented 3 years previously with syncope, palpitations, and combined mitral and tricuspid valve prolapse. The fourth family had 3 members with auscultatory and ultrasonic manifestations of billowing mitral valve, whereas the fourth member had "silent mitral valve prolapse." The fifth family represented a mother with auscultatory and echographic evidence of mitral valve prolapse; her 14-year-old daughter had both mitral and tricuspid valve prolapse, whereas the son had a bicuspid aortic valve. Both children were products of a prior marriage, and her husband has symptomatic mitral valve prolapse. We conclude that matrimonial mitral valve prolapse probably reflects the purported (6--10%) prevalence of this disorder in the general population. The consequences of such marital union on progeny is currently unclear and warrants future investigation.

  4. Mitral valve prolapse and hyperthyroidism: effect of patient selection.

    Science.gov (United States)

    Zullo, M A; Devereux, R B; Kramer-Fox, R; Lutas, E M; Brown, W T

    1985-11-01

    Patients with mitral valve prolapse and hyperthyroidism have common symptoms; the most outstanding symptom is palpitation. To determine whether or not common symptoms contributed to the reported association of these conditions, we evaluated 220 patients with symptomatic mitral valve prolapse and 216 first-degree relatives in 72 families; 65 relatives with mitral valve prolapse and 151 relatives without mitral valve prolapse, all greater than or equal to 16 years of age. Thirty subjects, aged 49 +/- 13 years (p less than 0.025 vs entire study group), had thyroid disease (23 subjects had definite thyroid disease, seven subjects had probable); 27 of 30 subjects with thyroid disease (90%) were female (p less than 0.005). The age- and sex-adjusted prevalence of hyperthyroidism was significantly higher in probands with mitral valve prolapse than in family members without mitral valve prolapse (3.5% vs 0%, p = 0.03), while an intermediate prevalence of hyperthyroidism (2.2%) was observed in family members with mitral valve prolapse. Thus, the prevalence of hyperthyroidism is increased among symptomatic patients with mitral valve prolapse as compared to family members without mitral valve prolapse, but the prevalence of thyroid conditions is similar among family members with or without this condition. These findings are explained by the effect of common symptoms on clinical detection of both mitral valve prolapse and hyperthyroidism.

  5. What Is Heart Valve Surgery?

    Science.gov (United States)

    ... working correctly. Most valve replacements involve the aortic Tricuspid valve and mitral valves. The aortic valve separates ... where it shouldn’t. This is called incompetence, insufficiency or regurgitation. • Prolapse — mitral valve flaps don’t ...

  6. What Is Heart Valve Disease?

    Science.gov (United States)

    ... 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 ...

  7. Full closure strategic analysis.

    Science.gov (United States)

    2014-07-01

    The full closure strategic analysis was conducted to create a decision process whereby full roadway : closures for construction and maintenance activities can be evaluated and approved or denied by CDOT : Traffic personnel. The study reviewed current...

  8. Sternal exploration or closure

    Science.gov (United States)

    VAC - vacuum-assisted closure - sternal wound; Sternal dehiscence; Sternal infection ... in the wound to look for signs of infection Remove dead or infected ... use a VAC (vacuum-assisted closure) dressing. It is a negative ...

  9. Self-testing security sensor for monitoring closure of vault doors and the like

    International Nuclear Information System (INIS)

    Cawthorne, D.C.

    1997-01-01

    A self-testing device is provided for a monitoring system for monitoring whether a closure member such as a door or window is closed. The monitoring system includes a switch unit mounted on the frame of the closure member being monitored and including magnetically biased switches connected in one or more electrical monitoring circuits, and a door magnet unit mounted on the closure member being monitored. The door magnet includes one or more permanent magnets that produce a magnetic field which, when the closure member is closed, cause said switches to assume a first state. When the closure member is opened, the switches switch to a second, alarm state. The self-testing device is electrically controllable from a remote location and produces a canceling or diverting magnetic field which simulates the effect of movement of the closure member from the closed position thereof without any actual movement of the member. 5 figs

  10. Effects of valve timing, valve lift and exhaust backpressure on performance and gas exchanging of a two-stroke GDI engine with overhead valves

    International Nuclear Information System (INIS)

    Dalla Nora, Macklini; Lanzanova, Thompson Diórdinis Metzka; Zhao, Hua

    2016-01-01

    Highlights: • Two-stroke operation was achieved in a four-valve direct injection gasoline engine. • Shorter valve opening durations improved torque at lower engine speeds. • The longer the valve opening duration, the lower was the air trapping efficiency. • Higher exhaust backpressure and lower valve lift reduced the compressor work. - Abstract: The current demand for fuel efficient and lightweight powertrains, particularly for application in downsized and hybrid electric vehicles, has renewed the interest in two-stroke engines. In this framework, an overhead four-valve spark-ignition gasoline engine was modified to run in the two-stroke cycle. The scavenging process took place during a long valve overlap period around bottom dead centre at each crankshaft revolution. Boosted intake air was externally supplied at a constant pressure and gasoline was directly injected into the cylinder after valve closure. Intake and exhaust valve timings and lifts were independently varied through an electrohydraulic valve train, so their effects on engine performance and gas exchanging were investigated at 800 rpm and 2000 rpm. Different exhaust backpressures were also evaluated by means of exhaust throttling. Air trapping efficiency, charging efficiency and scavenge ratio were calculated based on air and fuel flow rates, and exhaust oxygen concentration at fuel rich conditions. The results indicated that longer intake and exhaust valve opening durations increased the charge purity and hence torque at higher engine speeds. At lower speeds, although, shorter valve opening durations increased air trapping efficiency and reduced the estimated supercharger power consumption due to lower air short-circuiting. A strong correlation was found between torque and charging efficiency, while air trapping efficiency was more associated to exhaust valve opening duration. The application of exhaust backpressure, as well as lower intake/exhaust valve lifts, made it possible to increase

  11. Closure The Definitive Guide

    CERN Document Server

    Bolin, Michael

    2010-01-01

    If you're ready to use Closure to build rich web applications with JavaScript, this hands-on guide has precisely what you need to learn this suite of tools in depth. Closure makes it easy for experienced JavaScript developers to write and maintain large and complex codebases -- as Google has demonstrated by using Closure with Gmail, Google Docs, and Google Maps. Author and Closure contributor Michael Bolin has included numerous code examples and best practices, as well as valuable information not available publicly until now. You'll learn all about Closure's Library, Compiler, Templates, tes

  12. Mechanisms of mechanical heart valve cavitation: investigation using a tilting disk valve model.

    Science.gov (United States)

    He, Z; Xi, B; Zhu, K; Hwang, N H

    2001-09-01

    The induction of mechanical heart valve (MHV) cavitation was investigated using a 27 mm Medtronic Hall (MH27) tilting disk valve. The MH27 valve was mounted in the mitral position of a simulating pulse flow system, and stroboscopic lighting used to visualize cavitation bubbles on the occluder inflow surface at the instant of valve closure. MHV cavitation was monitored using a digital camera with 0.04 mm/pixel resolution sufficient to render the tiny bubbles clearly visible on the computer monitor screen. Cavitation on MH27 valve was classified as five types according to the time, site and shape of the cavitation bubbles. Valve cavitation occurred at the instant of occluder impact with the valve seat at closing. The impact motion was subdivided into three temporal phases: (i) squeezing flow; (ii) elastic collision; and (iii) leaflet rebound. MHV cavitation caused by vortices was found to be initiated by the squeezing jet and/or by the transvalvular leakage jets. By using a tension wave which swept across the occluder surface immediately upon elastic impact, nuclei in the vortex core were expanded to form cavitation bubbles. Analysis of the shape and location of the cavitation bubbles permitted a better understanding of MHV cavitation mechanisms, based on the fluid dynamics of jet vortex and tension wave propagations.

  13. Microfluidic sieve valves

    Science.gov (United States)

    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.

  14. Rotary pneumatic valve

    Science.gov (United States)

    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.

  15. Mitral Valve Stenosis

    Science.gov (United States)

    ... the left ventricle from flowing backward. A defective heart valve fails to either open or close fully. Risk factors Mitral valve stenosis is less common today than it once was because the most common cause, ... other heart valve problems, mitral valve stenosis can strain your ...

  16. Aortic Valve Stenosis

    Science.gov (United States)

    ... most cases, doctors don't know why a heart valve fails to develop properly, so it isn't something you could have prevented. Calcium buildup on the valve. With age, heart valves may accumulate deposits of calcium (aortic valve ...

  17. Remote actuated valve implant

    Science.gov (United States)

    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.

  18. Scissor thrust valve actuator

    Science.gov (United States)

    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.

  19. NRC perspective and experience on valve testing

    International Nuclear Information System (INIS)

    Eapen, P.K.

    1990-01-01

    Testing of safety related valves is one of the major activities at commercial nuclear power plants. In addition to Technical Specification, valve testing is required in 10 CFR 50.55a and 10 CFR 50 Appendix J. NRC inspectors (both resident and specialists) spend a considerable amount of time in following the valve test activities as part of their routine business. In the past, depending on a licensee's organizational structure, a valve could be tested more than three times to verify conformance with Technical Specifications, 10 CFR 50.55a, and 10 CFR 50 Appendix J. The regulatory reviewers were isolated from each other. Licensee test personnel were also not communicating among themselves. As a result, NRC inspectors found that certain valves in the IST program were inadequately tested. The typical licensee response was to say that this valve is exempted from testing under Appendix J. Others would say that the technical specification does not require fast closure of a valve in question. In addition to the above, the inspectors had to deal with exemption requests that were not dispositioned by the NRC. In the seventies there was a gentlemen's agreement to allow the licensee to do the testing in accordance with the exception, without waiting for the NRC approval. Needless to say when the new NRC inspection procedure was issued in March 1989 for implementation, the Regional inspectors had extremely difficult time to cope with the gray areas of valve testing. In August 1987, NRC Region I was reorganized and the special test program section was established to perform inspections in the IST area. This section was chartered to optimize resources and develop a meaningful inspection plan. The perspectives and insights used in the development of a detailed inspection plan is discussed below

  20. What caused the failures of the solenoid valve screws

    International Nuclear Information System (INIS)

    Vassallo, T.P.; Mumford, J.R.; Hossain, F.

    2001-01-01

    At Seabrook Station on May 5,1998 following a lengthy purge of the pressurizer steam space through Containment isolation sample valve 1-RC-FV-2830, the UL status light associated with this solenoid valve did not come on when the valve was closed from the plant's main control board. The UL status light is used to confirm valve closure position to satisfy the plant's Technical Specification requirements. The incorrect valve position indication on the main control board was initially believed to have resulted from excessive heat from a failed voltage control module that did not reduce the voltage to the valve's solenoid coil. This conclusion was based on a similar event that occurred in November of 1996. Follow-up in-plant testing of the valve determined that the voltage control module had not failed and was functioning satisfactorily. Subsequent investigations determined the root cause of the event to be excessive heat-up of the valve caused by high process fluid temperature and an excessively long purge of the pressurizer. The excessive heat-up of the valve from the high temperature process fluid weakened the magnetic field strength of the valve stem magnet to the extent that the UL status light reed switch would not actuate when the valve was closed. Since the voltage control module was tested and found to be functioning properly it was not replaced. Only the UL status light reed switch was replaced with a more sensitive reed that would respond better to a reduced magnetic field strength that results from a hot magnet. During reed switch replacement, three terminal block screws in the valve housing were found fractured and three other terminal block screws fractured during determination of the electrical conductors. This paper describes the initial plant event and ensuing laboratory tests and examinations that were performed to determine the root cause of the failure of the terminal block screws from the Containment isolation sample solenoid valve. (author)

  1. A Political Analysis of Community Influence over School Closure

    Science.gov (United States)

    Finnigan, Kara S.; Lavner, Mark

    2012-01-01

    This study seeks to understand community member participation in and influence over an urban school district's school closure process. Data from interviews with School Board members, district administrators, and community members, as well as district documents and newspaper articles suggest that district administrators limited participation…

  2. Which valve is which?

    Directory of Open Access Journals (Sweden)

    Pravin Saxena

    2015-01-01

    Full Text Available A 25-year-old man presented with a history of breathlessness for the past 2 years. He had a history of operation for Tetralogy of Fallot at the age of 5 years and history suggestive of Rheumatic fever at the age of 7 years. On echocardiographic examination, all his heart valves were severely regurgitating. Morphologically, all the valves were irreparable. The ejection fraction was 35%. He underwent quadruple valve replacement. The aortic and mitral valves were replaced by metallic valve and the tricuspid and pulmonary by tissue valve.

  3. Reversal of severe mitral regurgitation by device closure of a large patent ductus arteriosus in a premature infant.

    Science.gov (United States)

    Kheiwa, Ahmed; Ross, Robert D; Kobayashi, Daisuke

    2017-01-01

    We report a critically ill premature infant with severe mitral valve regurgitation associated with pulmonary hypertension and a severely dilated left atrium from a large patent ductus arteriosus. The mitral valve regurgitation improved significantly with normalisation of left atrial size 4 weeks after percutaneous closure of the patent ductus arteriosus. This case highlights the potential reversibility of severe mitral valve regurgitation with treatment of an underlying cardiac shunt.

  4. Strategic Planning for Hot Cell Closure

    International Nuclear Information System (INIS)

    LANGSTAFF, D.C.

    2001-01-01

    The United States Department of Energy (DOE) and its contractor were remediating a large hot cell complex to mitigate the radiological hazard. A Resource Conservation and Recovery Act (RCRA) closure unit was determined to be located within the complex. The regulator established a challenge to develop an acceptable closure plan on a short schedule (four months). The scope of the plan was to remove all excess equipment and mixed waste from the closure unit, establish the requirements of the legally binding Closure Plan and develop an acceptable schedule. The complex has several highly radioactive tanks, tank vaults, piping, and large hot cells containing complex chemical processing equipment. Driven by a strong need to develop an effective strategy to meet cleanup commitments, three principles were followed to develop an acceptable plan: (1) Use a team approach, (2) Establish a buffer zone to support closure, and (3) Use good practice when planning the work sequence. The team was composed of DOE, contractor, and Washington State Department of Ecology (Regulator) staff. The team approach utilized member expertise and fostered member involvement and communication. The buffer zone established an area between the unregulated parts of the building and the areas that were allegedly not in compliance with environmental standards. Introduction of the buffer zone provided simplicity, clarity, and flexibility into the process. Using good practice means using the DOE Integrated Safety Management Core Functions for planning and implementing work safely. Paying adequate attention to detail when the situation required contributed to the process credibility and a successful plan

  5. Bioprosthetic Valve Fracture Improves the Hemodynamic Results of Valve-in-Valve Transcatheter Aortic Valve Replacement.

    Science.gov (United States)

    Chhatriwalla, Adnan K; Allen, Keith B; Saxon, John T; Cohen, David J; Aggarwal, Sanjeev; Hart, Anthony J; Baron, Suzanne J; Dvir, Danny; Borkon, A Michael

    2017-07-01

    Valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) may be less effective in small surgical valves because of patient/prosthesis mismatch. Bioprosthetic valve fracture (BVF) using a high-pressure balloon can be performed to facilitate VIV TAVR. We report data from 20 consecutive clinical cases in which BVF was successfully performed before or after VIV TAVR by inflation of a high-pressure balloon positioned across the valve ring during rapid ventricular pacing. Hemodynamic measurements and calculation of the valve effective orifice area were performed at baseline, immediately after VIV TAVR, and after BVF. BVF was successfully performed in 20 patients undergoing VIV TAVR with balloon-expandable (n=8) or self-expanding (n=12) transcatheter valves in Mitroflow, Carpentier-Edwards Perimount, Magna and Magna Ease, Biocor Epic and Biocor Epic Supra, and Mosaic surgical valves. Successful fracture was noted fluoroscopically when the waist of the balloon released and by a sudden drop in inflation pressure, often accompanied by an audible snap. BVF resulted in a reduction in the mean transvalvular gradient (from 20.5±7.4 to 6.7±3.7 mm Hg, P valve effective orifice area (from 1.0±0.4 to 1.8±0.6 cm 2 , P valves to facilitate VIV TAVR with either balloon-expandable or self-expanding transcatheter valves and results in reduced residual transvalvular gradients and increased valve effective orifice area. © 2017 American Heart Association, Inc.

  6. Design And Analysis Of A Camless Valve Mechanism For I.C Engines Using Rotary Disc Valves

    Directory of Open Access Journals (Sweden)

    Vivek Jitendra Panchal

    2017-09-01

    Full Text Available It is the object of the presented paper to provide an electromechanical rotary valve actuating system for opening and closing valves of an internal combustion engine capable of separately controlling both the inlet and exhaust valve operations of each individual cylinder in a multi-cylinder engine. This indicates that only one valve will be required for each cylinder of the engine. Previously published versions of this concept require a separate valve for intake and exhaust in each cylinder. The system provides an alternative to the camshaft assembly in an attempt to overcome the limitations and inadequacies inevitably posed by a fully mechanical system. The prototype development is approached in a theoretical manner beginning with the conceptualization and design of a rotating disk with a notches and corresponding closure surfaces to open and close the flow path. The actuated disk and notch design is then refined and followed by the design of an inlet and exhaust manifold to correspond to the valve design and the theorizing and design of a sealing gasket. The rotating speed of the valve is determined by a general idling speed and can be varied to provide variable valve timing with the motor. The final assembly eliminates a majority of the moving parts currently used in camshaft systems like the cam camshaft rocker arm push rod and springs and results in a significantly lighter valve actuation system. By eliminating the translatory motion of valves the problem of valves slamming on the valve seats at high velocities is eliminated thus greatly reducing engine wear.

  7. Magnetisable container closure and means for its removal

    International Nuclear Information System (INIS)

    Barrett, W.I.

    1984-01-01

    A container has a closed lower end and an open upper end, is made of a non-magnetic material such as aluminium, and has a peripheral groove spaced from the open end. A disc-like closure is of magnetic material such as ferritic steel, has a pair of spring jaws joined to the disc by a joining member such that when the disc of the closure is in position closing the open end of the container, the jaws engage in groove and hold the closure in position. To remove the closure, it is engaged by magnetic means mounted for example on a wall and having a step such that when the container is moved laterally away the closure is retained by the magnetic means aided by the step and thereby the closure becomes removed from the container. (author)

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

    Science.gov (United States)

    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. Mitral Valve Prolapse

    Science.gov (United States)

    ... valve syndrome . What happens during MVP? Watch an animation of mitral valve prolapse When the heart pumps ( ... our brochures Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

  10. Problem: Mitral Valve Regurgitation

    Science.gov (United States)

    ... each time the left ventricle contracts. Watch an animation of mitral valve regurgitation A leaking mitral valve ... Not Alone Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

  11. Problem: Heart Valve Regurgitation

    Science.gov (United States)

    ... should be completely closed For example: Watch an animation of mitral valve regurgitation A leaking mitral valve ... Not Alone Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

  12. Aortic valve surgery - open

    Science.gov (United States)

    ... gov/ency/article/007408.htm Aortic valve surgery - open To use the sharing features on this page, ... separates the heart and aorta. The aortic valve opens so blood can flow out. It then closes ...

  13. Corrosion of valve metals

    International Nuclear Information System (INIS)

    Draley, J.E.

    1976-01-01

    A general survey related to the corrosion of valve metals or film-forming metals. The way these metals corrode with some general examples is described. Valve metals form relatively perfect oxide films with little breakdown or leakage when anodized

  14. Mitral valve surgery - open

    Science.gov (United States)

    ... Taking warfarin (Coumadin) References Otto CM, Bonow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ... A.M. Editorial team. Heart Surgery Read more Heart Valve Diseases Read more Mitral Valve Prolapse Read more A. ...

  15. Swing check valve

    International Nuclear Information System (INIS)

    Eminger, H.E.

    1977-01-01

    A swing check valve which includes a valve body having an inlet and outlet is described. A recess in the valve body designed to hold a seal ring and a check valve disc swingable between open and closed positions. The disc is supported by a high strength wire secured at one end in a support spacer pinned through bearing blocks fixed to the valve body and at its other end in a groove formed on the outer peripheral surface of the disc. The parts are designed and chosen such to provide a lightweight valve disc which is held open by minimum velocity of fluid flowing through the valve which thus reduces oscillations and accompanying wear of bearings supporting the valve operating parts. (Auth.)

  16. Transcatheter pulmonary valve replacement by hybrid approach using a novel polymeric prosthetic heart valve: proof of concept in sheep.

    Directory of Open Access Journals (Sweden)

    Ben Zhang

    Full Text Available Since 2000, transcatheter pulmonary valve replacement has steadily advanced. However, the available prosthetic valves are restricted to bioprosthesis which have defects like poor durability. Polymeric heart valve is thought as a promising alternative to bioprosthesis. In this study, we introduced a novel polymeric transcatheter pulmonary valve and evaluated its feasibility and safety in sheep by a hybrid approach.We designed a novel polymeric trileaflet transcatheter pulmonary valve with a balloon-expandable stent, and the valve leaflets were made of 0.1-mm expanded polytetrafluoroethylene (ePTFE coated with phosphorylcholine. We chose glutaraldehyde-treated bovine pericardium valves as control. Pulmonary valve stents were implanted in situ by a hybrid transapical approach in 10 healthy sheep (8 for polymeric valve and 2 for bovine pericardium valve, weighing an average of 22.5±2.0 kg. Angiography and cardiac catheter examination were performed after implantation to assess immediate valvular functionality. After 4-week follow-up, angiography, echocardiography, computed tomography, and cardiac catheter examination were used to assess early valvular function. One randomly selected sheep with polymeric valve was euthanized and the explanted valved stent was analyzed macroscopically and microscopically.Implantation was successful in 9 sheep. Angiography at implantation showed all 9 prosthetic valves demonstrated orthotopic position and normal functionality. All 9 sheep survived at 4-week follow-up. Four-week follow-up revealed no evidence of valve stent dislocation or deformation and normal valvular and cardiac functionality. The cardiac catheter examination showed the peak-peak transvalvular pressure gradient of the polymeric valves was 11.9±5.0 mmHg, while that of two bovine pericardium valves were 11 and 17 mmHg. Gross morphology demonstrated good opening and closure characteristics. No thrombus or calcification was seen macroscopically

  17. Mitral Valve Prolapse

    Science.gov (United States)

    Mitral valve prolapse (MVP) occurs when one of your heart's valves doesn't work properly. The flaps of the valve are "floppy" and ... to run in families. Most of the time, MVP doesn't cause any problems. Rarely, blood can ...

  18. Overflow control valve

    International Nuclear Information System (INIS)

    Kessinger, B.A.; Hundal, R.; Parlak, E.A.

    1982-01-01

    An overflow control valve for use in a liquid sodium coolant pump tank which can be remotely engaged with and disengaged from the pump tank wall to thereby permit valve removal. An actuating shaft for controlling the valve also has means for operating a sliding cylinder against a spring to retract the cylinder from sealing contact with the pump tank nozzle. (author)

  19. Fluid control valves

    International Nuclear Information System (INIS)

    Rankin, J.

    1980-01-01

    A fluid control valve is described in which it is not necessary to insert a hand or a tool into the housing to remove the valve seat. Such a valve is particularly suitable for the control of radioactive fluids since maintenance by remote control is possible. (UK)

  20. A remote control valve

    International Nuclear Information System (INIS)

    Cachard, Maurice de; Dumont, Maurice.

    1976-01-01

    This invention concerns a remote control valve for shutting off or distributing a fluid flowing at a high rate and low pressure. Among the different valves at present in use, electric valves are the most recommended for remote control but their reliability is uncertain and they soon become costly when large diameter valves are used. The valve described in this invention does away with this drawback owing to its simplicity and the small number of moving parts, this makes it particularly reliable. It mainly includes: a tubular body fitted with at least one side opening; at least one valve wedge for this opening, coaxial with the body, and mobile; a mobile piston integral with this wedge. Several valves to the specifications of this invention can be fitted in series (a shut-off valve can be used in conjunction with one or more distribution valves). The fitting and maintenance of the valve is very simple owing to its design. It can be fabricated in any material such as metals, alloys, plastics and concrete. The structure of the valve prevents the flowing fluid from coming into contact with the outside environment, thereby making it particularly suitable in the handling of dangerous or corrosive fluids. Finally, the opening and shutting of the valve occurs slowly, thereby doing away with the water hammer effect so frequent in large bore pipes [fr

  1. Heart Valve Diseases

    Science.gov (United States)

    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 ...

  2. Methods of estimation of mitral valve regurgitation for the cardiac surgeon

    Directory of Open Access Journals (Sweden)

    Baikoussis Nikolaos G

    2009-07-01

    Full Text Available Abstract Mitral valve regurgitation is a relatively common and important heart valve lesion in clinical practice and adequate assessment is fundamental to decision on management, repair or replacement. Disease localised to the posterior mitral valve leaflet or focal involvement of the anterior mitral valve leaflet is most amenable to mitral valve repair, whereas patients with extensive involvement of the anterior leaflet or incomplete closure of the valve are more suitable for valve replacement. Echocardiography is the recognized investigation of choice for heart valve disease evaluation and assessment. However, the technique is depended on operator experience and on patient's hemodynamic profile, and may not always give optimal diagnostic views of mitral valve dysfunction. Cardiac catheterization is related to common complications of an interventional procedure and needs a hemodynamic laboratory. Cardiac magnetic resonance (MRI seems to be a useful tool which gives details about mitral valve anatomy, precise point of valve damage, as well as the quantity of regurgitation. Finally, despite of its higher cost, cardiac MRI using cine images with optimized spatial and temporal resolution can also resolve mitral valve leaflet structural motion, and can reliably estimate the grade of regurgitation.

  3. Heavy gas valves

    Energy Technology Data Exchange (ETDEWEB)

    Steier, L [Vereinigte Armaturen Gesellschaft m.b.H., Mannheim (Germany, F.R.)

    1979-01-01

    Heavy gas valves must comply with special requirements. Apart from absolute safety in operation there are stringent requirements for material, sealing and ease of operation even in the most difficult conditions. Ball valves and single plate pipe gate valves lateral sealing rings have a dual, double sided sealing effect according to the GROVE sealing system. Single plate gate valves with lateral protective plates are suitable preferably for highly contaminated media. Soft sealing gate valves made of cast iron are used for low pressure applications.

  4. Fast valve for the National Synchrotron Light Source

    International Nuclear Information System (INIS)

    Oversluizen, T.

    1981-01-01

    A prototype fast closing, all metal, UHV-compatible valve has been built to protect the NSLS storage rings from sudden vacuum failures which may occur in the experimental beamlines. When triggered, an area of 10 x 140 mm is covered by a spring-driven, guillotine type blade, which forms a high impedance to the inrushing gas. This fast closure assures the protection of the ring vacuum from contamination before the slower UHV valve can be sealed off. Closing times on the order of 3 to 5 msec have been measured. The valve is triggered by a commercial solenoid, powered by a 16,800 μF capacitor bank at 100 volts. Because the valve is situated in a high radiation area, it is remotely resettable

  5. Relief valve testing study

    International Nuclear Information System (INIS)

    BROMM, R.D.

    2001-01-01

    Reclosing pressure-actuated valves, commonly called relief valves, are designed to relieve system pressure once it reaches the set point of the valve. They generally operate either proportional to the differential between their set pressure and the system pressure (gradual lift) or by rapidly opening fully when the set pressure is reached (pop action). A pop action valve allows the maximum fluid flow through the valve when the set pressure is reached. A gradual lift valve allows fluid flow in proportion to how much the system pressure has exceeded the set pressure of the valve (in the case of pressure relief) or has decreased below the set pressure (vacuum relief). These valves are used to protect systems from over and under pressurization. They are used on boilers, pressure vessels, piping systems and vacuum systems to prevent catastrophic failures of these systems, which can happen if they are under or over pressurized beyond the material tolerances. The construction of these valves ranges from extreme precision of less than a psi tolerance and a very short lifetime to extremely robust construction such as those used on historic railroad steam engines that are designed operate many times a day without changing their set pressure when the engines are operating. Relief valves can be designed to be immune to the effects of back pressure or to be vulnerable to it. Which type of valve to use depends upon the design requirements of the system

  6. Eyelid closure at death

    Directory of Open Access Journals (Sweden)

    A D Macleod

    2009-01-01

    Full Text Available Aim: To observe the incidence of full or partial eyelid closure at death. Materials and Methods: The presence of ptosis was recorded in 100 consecutive hospice patient deaths. Results: Majority (63% of the patients died with their eyes fully closed, however, 37% had bilateral ptosis at death, with incomplete eye closure. In this study, central nervous system tumor involvement and/or acute hepatic encephalopathy appeared to be pre-mortem risk factors of bilateral ptosis at death. Conclusion: Organicity and not psychogenicity is, therefore, the likely etiology of failure of full eyelid closure at death.

  7. Modeling of Dynamic Fluid Forces in Fast Switching Valves

    DEFF Research Database (Denmark)

    Roemer, Daniel Beck; Johansen, Per; Pedersen, Henrik Clemmensen

    2015-01-01

    Switching valves experience opposing fluid forces due to movement of the moving member itself, as the surrounding fluid volume must move to accommodate the movement. This movement-induced fluid force may be divided into three main components; the added mass term, the viscous term and the socalled...... history term. For general valve geometries there are no simple solution to either of these terms. During development and design of such switching valves, it is therefore, common practice to use simple models to describe the opposing fluid forces, neglecting all but the viscous term which is determined...... based on shearing areas and venting channels. For fast acting valves the opposing fluid force may retard the valve performance significantly, if appropriate measures are not taken during the valve design. Unsteady Computational Fluid Dynamics (CFD) simulations are available to simulate the total fluid...

  8. Inhibitory role of Notch1 in calcific aortic valve disease.

    Directory of Open Access Journals (Sweden)

    Asha Acharya

    Full Text Available Aortic valve calcification is the most common form of valvular heart disease, but the mechanisms of calcific aortic valve disease (CAVD are unknown. NOTCH1 mutations are associated with aortic valve malformations and adult-onset calcification in families with inherited disease. The Notch signaling pathway is critical for multiple cell differentiation processes, but its role in the development of CAVD is not well understood. The aim of this study was to investigate the molecular changes that occur with inhibition of Notch signaling in the aortic valve. Notch signaling pathway members are expressed in adult aortic valve cusps, and examination of diseased human aortic valves revealed decreased expression of NOTCH1 in areas of calcium deposition. To identify downstream mediators of Notch1, we examined gene expression changes that occur with chemical inhibition of Notch signaling in rat aortic valve interstitial cells (AVICs. We found significant downregulation of Sox9 along with several cartilage-specific genes that were direct targets of the transcription factor, Sox9. Loss of Sox9 expression has been published to be associated with aortic valve calcification. Utilizing an in vitro porcine aortic valve calcification model system, inhibition of Notch activity resulted in accelerated calcification while stimulation of Notch signaling attenuated the calcific process. Finally, the addition of Sox9 was able to prevent the calcification of porcine AVICs that occurs with Notch inhibition. In conclusion, loss of Notch signaling contributes to aortic valve calcification via a Sox9-dependent mechanism.

  9. RCRA corrective action and closure

    International Nuclear Information System (INIS)

    1995-02-01

    This information brief explains how RCRA corrective action and closure processes affect one another. It examines the similarities and differences between corrective action and closure, regulators' interests in RCRA facilities undergoing closure, and how the need to perform corrective action affects the closure of DOE's permitted facilities and interim status facilities

  10. Scope and closures

    CERN Document Server

    Simpson, Kyle

    2014-01-01

    No matter how much experience you have with JavaScript, odds are you don’t fully understand the language. This concise yet in-depth guide takes you inside scope and closures, two core concepts you need to know to become a more efficient and effective JavaScript programmer. You’ll learn how and why they work, and how an understanding of closures can be a powerful part of your development skillset.

  11. Guide to prosthetic cardiac valves

    International Nuclear Information System (INIS)

    Morse, D.; Steiner, R.M.; Fernandez, J.

    1985-01-01

    This book contains 10 chapters. Some of the chapter titles are: The development of artificial heart valves: Introduction and historical perspective; The radiology of prosthetic heart valves; The evaluation of patients for prosthetic valve implantation; Pathology of cardiac valve replacement; and Bioengineering of mechanical and biological heart valve substitutes

  12. Simulation of the behaviour of a servo actuated check valve upon rupture of the feedwater pipe

    International Nuclear Information System (INIS)

    Lucas, A.M. de; Perezagua, R.L.; Rosa, B. de la; Sanz, J.

    1995-01-01

    The steam generator replacement programme at Almaraz NPP, provides for the installation of a replacement damped non-return valve for the feedwater system. the function of this valve is to protect the steam generator in the event of a rupture in the feedwater pipe. Sudden closure of the check valve, against the flow and following rupture of the feedwater pipe, causes overpressure in the valve which is transmitted to the steam generator nozzle. It is therefore necessary to know this when designing the internal systems of the steam generator. Using the RELAP5/MODE3 code, it has been possible to simulate the dynamic behaviour of a check valve upon rupture of a feedwater pipe postulated outside the containment. The calculation model has been applied to different types of check valve. (Author)

  13. Intelligent Flow Control Valve

    Science.gov (United States)

    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.

  14. Nuclear valves latest development

    International Nuclear Information System (INIS)

    Isaac, F.; Monier, M.

    1993-01-01

    In the frame of Nuclear Power Plant upgrade (Emergency Power Supply and Emergency Core Cooling), Westinghouse had to face a new valve design philosophy specially for motor operated valves. The valves have to been designed to resist any operating conditions, postulated accident or loss of control. The requirements for motor operated valves are listed and the selected model and related upgrading explained. As part of plant upgrade and valves replacement, Westinghouse has sponsored alternative hardfacing research programme. Two types of materials have been investigated: nickel base alloys and iron base alloys. Programme requirements and test results are given. A new globe valve model (On-Off or regulating) is described developed by Alsthom Velan permitting the seat replacement in less than 10 min. (Z.S.) 2 figs

  15. Cryogenic Cam Butterfly Valve

    Science.gov (United States)

    McCormack, Kenneth J. (Inventor)

    2016-01-01

    A cryogenic cam butterfly valve has a body that includes an axially extending fluid conduit formed there through. A disc lug is connected to a back side of a valve disc and has a circular bore that receives and is larger than a cam of a cam shaft. The valve disc is rotatable for a quarter turn within the body about a lug axis that is offset from the shaft axis. Actuating the cam shaft in the closing rotational direction first causes the camming side of the cam of the cam shaft to rotate the disc lug and the valve disc a quarter turn from the open position to the closed position. Further actuating causes the camming side of the cam shaft to translate the valve disc into sealed contact with the valve seat. Opening rotational direction of the cam shaft reverses these motions.

  16. Low noise control valve

    International Nuclear Information System (INIS)

    Christie, R.S.

    1975-01-01

    Noise is one of the problems associated with the use of any type of control valve in systems involving the flow of fluids. The advent of OSHA standards has prompted control valve manufacturers to design valves with special trim to lower the sound pressure level to meet these standards. However, these levels are in some cases too high, particularly when a valve must be located in or near an area where people are working at tasks requiring a high degree of concentration. Such locations are found around and near research devices and in laboratory-office areas. This paper describes a type of fluid control device presently being used at PPL as a bypass control valve in deionized water systems and designed to reduce sound pressure levels considerably below OSHA standards. Details of the design and construction of this constant pressure drop variable flow control valve are contained in the text and are shown in photographs and drawings. Test data taken are included

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

    Science.gov (United States)

    2017-04-26

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

  18. Aortic valve replacement in a patient with severe nickel allergy.

    Science.gov (United States)

    Lusini, Mario; Barbato, Raffaele; Spadaccio, Cristiano; Chello, Massimo

    2011-11-01

    Nickel allergy can raise clinical problems in patients undergoing cardiac surgery who require sternal closure with stainless steel wire. We describe the case of a 51-year-old woman with severe nickel allergy who underwent aortic valve replacement with a nickel-free ON-X prosthesis and sternal closure by Fiberwire # 2 suture without complications. Considering its biocompatibility and its mechanical characteristics including optimal strength and knot resistance, this suture might be a viable alternative in patients in which the use of stainless steel wire is contraindicated. © 2011 Wiley Periodicals, Inc.

  19. Magnetic Check Valve

    Science.gov (United States)

    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.

  20. Butterfly valves for seawater

    International Nuclear Information System (INIS)

    Yamanaka, Katsuto

    1991-01-01

    Recently in thermal and nuclear power stations and chemical plants which have become large capacity, large quantity of cooling water is required, and mostly seawater is utilized. In these cooling water systems, considering thermal efficiency and economy, the pipings become complex, and various control functions are demanded. For the purpose, the installation of shut-off valves and control valves for pipings is necessary. The various types of valves have been employed, and in particular, butterfly valves have many merits in their function, size, structure, operation, maintenance, usable period, price and so on. The corrosion behavior of seawater is complicated due to the pollution of seawater, therefore, the environment of the valves used for seawater became severe. The structure and the features of the butterfly valves for seawater, the change of the structure of the butterfly valves for seawater and the checkup of the butterfly valves for seawater are reported. The corrosion of metallic materials is complicatedly different due to the locating condition of plants, the state of pipings and the condition of use. The corrosion countermeasures for butterfly valves must be examined from the synthetic viewpoints. (K.I.)

  1. Redo mitral valve surgery

    Directory of Open Access Journals (Sweden)

    Redoy Ranjan

    2018-03-01

    Full Text Available This study is based on the findings of a single surgeon’s practice of mitral valve replacement of 167 patients from April 2005 to June 2017 who developed symptomatic mitral restenosis after closed or open mitral commisurotomy. Both clinical and color doppler echocardiographic data of peri-operative and six months follow-up period were evaluated and compared to assess the early outcome of the redo mitral valve surgery. With male-female ratio of 1: 2.2 and after a duration of 6 to 22 years symptom free interval between the redo procedures, the selected patients with mitral valve restenosis undergone valve replacement with either mechanical valve in 62% cases and also tissue valve in 38% cases. Particular emphasis was given to separate the adhered pericardium from the heart completely to ameliorate base to apex and global contraction of the heart. Besides favorable post-operative clinical outcome, the echocardiographic findings were also encouraging as there was statistically significant increase in the mitral valve area and ejection fraction with significant decrease in the left atrial diameter, pressure gradient across the mitral valve and pulmonary artery systolic pressure. Therefore, in case of inevitable mitral restenosis after closed or open commisurotomy, mitral valve replacement is a promising treatment modality.

  2. Diseases of the Tricuspid Valve

    Science.gov (United States)

    ... stenosis. Tricuspid Regurgitation Tricuspid regurgitation is also called tricuspid insufficiency or tricuspid incompetence. It means there is a ... require valve surgery. Tags: heart valves , tricuspid incompetence , ... tricuspid regurgitation , tricuspid stenosis , valve disease Related Links ...

  3. Development of Glassy Carbon Blade for LHC Fast Vacuum Valve

    CERN Document Server

    Coly, P

    2012-01-01

    An unexpected gas inrush in a vacuum chamber leads to the development of a fast pressure wave. It carries small particles that can compromise functionality of sensitive machine systems such as the RF cavities or kickers. In the LHC machine, it has been proposed to protect this sensitive equipment by the installation of fast vacuum valves. The main requirements for the fast valves and in particular for the blade are: fast closure in the 20 ms range, high transparency and melting temperature in case of closure with beam in, dust free material to not contaminate sensitive adjacent elements, and last but not least vacuum compatibility and adequate leak tightness across the blade. In this paper, different designs based on a vitreous carbon blade are presented and a solution is proposed. The main reasons for this material choice are given. The mechanical study of the blade behaviour under dynamic forces is shown.

  4. Tank closure reducing grout

    International Nuclear Information System (INIS)

    Caldwell, T.B.

    1997-01-01

    A reducing grout has been developed for closing high level waste tanks at the Savannah River Site in Aiken, South Carolina. The grout has a low redox potential, which minimizes the mobility of Sr 90 , the radionuclide with the highest dose potential after closure. The grout also has a high pH which reduces the solubility of the plutonium isotopes. The grout has a high compressive strength and low permeability, which enhances its ability to limit the migration of contaminants after closure. The grout was designed and tested by Construction Technology Laboratories, Inc. Placement methods were developed by the Savannah River Site personnel

  5. Danfos: Thermostatic Radiator Valves

    DEFF Research Database (Denmark)

    Gregersen, Niels; Oliver, James; Hjorth, Poul G.

    2000-01-01

    This problem deals with modelling the flow through a typical Danfoss thermostatic radiator valve.Danfoss is able to employ Computational Fluid Dynamics (CFD) in calculations of the capacity of valves, but an experienced engineer can often by rules of thumb "guess" the capacity, with a precision...

  6. Bioprinting a cardiac valve.

    Science.gov (United States)

    Jana, Soumen; Lerman, Amir

    2015-12-01

    Heart valve tissue engineering could be a possible solution for the limitations of mechanical and biological prostheses, which are commonly used for heart valve replacement. In tissue engineering, cells are seeded into a 3-dimensional platform, termed the scaffold, to make the engineered tissue construct. However, mimicking the mechanical and spatial heterogeneity of a heart valve structure in a fabricated scaffold with uniform cell distribution is daunting when approached conventionally. Bioprinting is an emerging technique that can produce biological products containing matrix and cells, together or separately with morphological, structural and mechanical diversity. This advance increases the possibility of fabricating the structure of a heart valve in vitro and using it as a functional tissue construct for implantation. This review describes the use of bioprinting technology in heart valve tissue engineering. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. Space Vehicle Valve System

    Science.gov (United States)

    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.

  8. Multiple-port valve

    International Nuclear Information System (INIS)

    Doody, T.J.

    1978-01-01

    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 with one or more of a plurality of secondary conduits fitting 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

  9. Low radiation dose non-contrast cardiac CT: is it of value in the evaluation of mechanical aortic valve

    International Nuclear Information System (INIS)

    Bazeed, Mohamed Fayez; Moselhy, Mohamed Saleh; Rezk, Ahmad Ibrahim; Al-Murayeh, Mushabab Ayedh

    2012-01-01

    Background: Prosthetic bileaflet mechanical valve function has been traditionally evaluated using echocardiography and fluoroscopy. Multidetector computed tomography (MDCT) is a novel technique for cardiac evaluation. Purpose: To evaluate bileaflet mechanical aortic valves using a low-milliampere (mA), non-contrast MDCT protocol with a limited scan range. Material and Methods: Forty patients with a bileaflet mechanical aortic valve were evaluated using a non-contrast, low-mA, ECG-gated 64 MDCT protocol with a limited scan range. MDCT findings of opening and closing valve angles were correlated to fluoroscopy and echocardiography. Also, the valve visibility was evaluated on MDCT and fluoroscopy according to a 3-point grading scale. Results: The visualization score with the MDCT was significantly superior to the fluoroscopy (3 vs. 2.7). A strong correlation was noted between the opening (r = 0.82) and closing (r = 0.96) valve angles with MDCT and fluoroscopy without a statistically significant difference (P = 0.31 and 0.16, respectively). The mean effective radiation dose of the suggested protocol was 4 ± 0.5 mSv. Five valves were evaluated using transesophageal echocardiography because the valves were difficult to evaluate with transthoracic echocardiography, and all of these valves were evaluated optimally with MDCT. A high-pressure gradient was noted in nine valves, and the MDCT showed that seven of these valves inadequately opened, and two valves opened well, which resulted in patient valve mismatch. Incomplete valve closure was noted in five valves, and the echocardiography showed significant transvalvular regurgitation in all five valves. Conclusion: MDCT can provide a precise measurement of valve function and can potentially evaluate high-pressure gradients and transvalvular regurgitation

  10. Low radiation dose non-contrast cardiac CT: is it of value in the evaluation of mechanical aortic valve

    Energy Technology Data Exchange (ETDEWEB)

    Bazeed, Mohamed Fayez (Dept. of Diagnostic Radiology, Faculty of Medicine, Mansoura Univ. (Egypt)), email: m_bazeed@yahoo.com; Moselhy, Mohamed Saleh (Cardiology Dept. Faculty of Medicine, Suez Canal Univ. (Egypt)); Rezk, Ahmad Ibrahim (Dept. of Cardiac Surgery, Faculty of Medicine, Aim Shams Univ. (Egypt)); Al-Murayeh, Mushabab Ayedh (Dept. of Cardiac Services, Armed Forces Hospitals Southern Region (Saudi Arabia))

    2012-05-15

    Background: Prosthetic bileaflet mechanical valve function has been traditionally evaluated using echocardiography and fluoroscopy. Multidetector computed tomography (MDCT) is a novel technique for cardiac evaluation. Purpose: To evaluate bileaflet mechanical aortic valves using a low-milliampere (mA), non-contrast MDCT protocol with a limited scan range. Material and Methods: Forty patients with a bileaflet mechanical aortic valve were evaluated using a non-contrast, low-mA, ECG-gated 64 MDCT protocol with a limited scan range. MDCT findings of opening and closing valve angles were correlated to fluoroscopy and echocardiography. Also, the valve visibility was evaluated on MDCT and fluoroscopy according to a 3-point grading scale. Results: The visualization score with the MDCT was significantly superior to the fluoroscopy (3 vs. 2.7). A strong correlation was noted between the opening (r = 0.82) and closing (r = 0.96) valve angles with MDCT and fluoroscopy without a statistically significant difference (P = 0.31 and 0.16, respectively). The mean effective radiation dose of the suggested protocol was 4 +- 0.5 mSv. Five valves were evaluated using transesophageal echocardiography because the valves were difficult to evaluate with transthoracic echocardiography, and all of these valves were evaluated optimally with MDCT. A high-pressure gradient was noted in nine valves, and the MDCT showed that seven of these valves inadequately opened, and two valves opened well, which resulted in patient valve mismatch. Incomplete valve closure was noted in five valves, and the echocardiography showed significant transvalvular regurgitation in all five valves. Conclusion: MDCT can provide a precise measurement of valve function and can potentially evaluate high-pressure gradients and transvalvular regurgitation

  11. Professional Closure Beyond State Authorization

    Directory of Open Access Journals (Sweden)

    Gitte Sommer Harrits

    2014-03-01

    Full Text Available For decades, the Weberian approach to the study of professions has been strong, emphasizing state authorization and market monopolies as constituting what is considered a profession. Originally, however, the Weberian conception of closure, or the ways in which a profession is constituted and made separate, was broader. This article suggests a revision of the closure concept, integrating insights from Pierre Bourdieu, and conceptualizing professional closure as the intersection of social, symbolic and legal closure. Based on this revision, this article demonstrates how to apply such a concept in empirical studies. This is done by exploring social, symbolic and legal closure across sixteen professional degree programs. The analyses show a tendency for some overlap between different forms of closure, with a somewhat divergent pattern for legal closure. Results support the argument that we need to study these processes as an intersection of different sources of closure, including capital, lifestyles and discourse

  12. MNC Subsidiary Closures

    DEFF Research Database (Denmark)

    Sofka, Wolfgang; Torres Preto, Miguel; de Faria, Pedro

    2014-01-01

    We investigate the consequences of MNC subsidiary closures for employees who lose their jobs. In particular, we examine the extent to which the human capital that these employees acquired while employed by the MNC influences the wages they receive in their new jobs. We propose an employee...

  13. Friction or Closure

    DEFF Research Database (Denmark)

    Lundahl, Mikela

    2014-01-01

    Heritage is a discourse that aims at closure. It fixates the narrative of the past through the celebration of specific material (or sometimes immaterial non-) ob-jects. It organizes temporality and construct events and freezes time. How does this unfold in the case of the UNESCO World Heritage si...

  14. Mail Office annual closure

    CERN Multimedia

    2013-01-01

    On the occasion of the annual closure of CERN, there will be no mail distributed on Friday 20 December 2013 but mail will be collected in the morning. Nevertheless, you will still be able to bring your outgoing mail to Building 555-R-002 until 12 noon.  

  15. Ring closure in actin polymers

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Supurna, E-mail: supurna@rri.res.in [Raman Research Institute, Bangalore 560080 (India); Chattopadhyay, Sebanti [Doon University, Dehradun 248001 (India)

    2017-03-18

    We present an analysis for the ring closure probability of semiflexible polymers within the pure bend Worm Like Chain (WLC) model. The ring closure probability predicted from our analysis can be tested against fluorescent actin cyclization experiments. We also discuss the effect of ring closure on bend angle fluctuations in actin polymers. - Highlights: • Ring closure of biopolymers. • Worm like chain model. • Predictions for experiments.

  16. Closure for container, especially for the storage and transport of radioactive and/or toxic substances

    International Nuclear Information System (INIS)

    Kuester, K.; Peters, R.

    1988-01-01

    The closure consists of a rotating valve in a housing which is rotatable around its axis and provided with a boring vertical to its circumference. For loading and unloading the boring can be aligned with the feeding shaft of the container by turning the rotating valve. The rotating valve exhibits a closed hollow roll. At both ends the boring is made up of a guide tube crossing the hollow roll in a radial direction and ending in the jacket of the hollow roll. A radial stand shaft with open ending in the jacket of the hollow roll is provided. The shaft is inserted into a recess covering part of the hollow roll jacket and its walls are connected with the jacket of the guide tube. By this closure it is possible to obtain a minimum overall height and optimum shielding without additional measures. (orig./HP) [de

  17. CIRSE Vascular Closure Device Registry

    NARCIS (Netherlands)

    Reekers, Jim A.; Müller-Hülsbeck, Stefan; Libicher, Martin; Atar, Eli; Trentmann, Jens; Goffette, Pierre; Borggrefe, Jan; Zeleňák, Kamil; Hooijboer, Pieter; Belli, Anna-Maria

    2011-01-01

    Vascular closure devices are routinely used after many vascular interventional radiology procedures. However, there have been no major multicenter studies to assess the safety and effectiveness of the routine use of closure devices in interventional radiology. The CIRSE registry of closure devices

  18. Crack closure, a literature study

    Science.gov (United States)

    Holmgren, M.

    1993-08-01

    In this report crack closure is treated. The state of the art is reviewed. Different empirical formulas for determining the crack closure are compared with each other, and their benefits are discussed. Experimental techniques for determining the crack closure stress are discussed, and some results from fatigue tests are also reported. Experimental data from the literature are reported.

  19. Gate valve performance prediction

    International Nuclear Information System (INIS)

    Harrison, D.H.; Damerell, P.S.; Wang, J.K.; Kalsi, M.S.; Wolfe, K.J.

    1994-01-01

    The Electric Power Research Institute is carrying out a program to improve the performance prediction methods for motor-operated valves. As part of this program, an analytical method to predict the stem thrust required to stroke a gate valve has been developed and has been assessed against data from gate valve tests. The method accounts for the loads applied to the disc by fluid flow and for the detailed mechanical interaction of the stem, disc, guides, and seats. To support development of the method, two separate-effects test programs were carried out. One test program determined friction coefficients for contacts between gate valve parts by using material specimens in controlled environments. The other test program investigated the interaction of the stem, disc, guides, and seat using a special fixture with full-sized gate valve parts. The method has been assessed against flow-loop and in-plant test data. These tests include valve sizes from 3 to 18 in. and cover a considerable range of flow, temperature, and differential pressure. Stem thrust predictions for the method bound measured results. In some cases, the bounding predictions are substantially higher than the stem loads required for valve operation, as a result of the bounding nature of the friction coefficients in the method

  20. Modeling valve leakage

    International Nuclear Information System (INIS)

    Bell, S.R.; Rohrscheib, R.

    1994-01-01

    The American Society of Mechanical Engineers (ASME) Code requires individual valve leakage testing for Category A valves. Although the U.S. Nuclear Regulatory Commission (USNRC) has recognized that it is more appropriate to test containment isolation valves in groups, as allowed by 10 CFR 50, Appendix J, a utility seeking relief from these Code requirements must provide technical justification for the relief and establish a conservative alternate acceptance criteria. In order to provide technical justification for group testing of containment isolation valves, Illinois Power developed a calculation (model) for determining the size of a leakage pathway in a valve disc or seat for a given leakage rate. The model was verified experimentally by machining leakage pathways of known size and then measuring the leakage and comparing this value to the calculated value. For the range of values typical of leakage rate testing, the correlation between the experimental values and calculated values was quote good. Based upon these results, Illinois Power established a conservative acceptance criteria for all valves in the inservice testing (IST) program and was granted relief by the USNRC from the individual leakage testing requirements of the ASME Code. This paper presents the results of Illinois Power's work in the area of valve leakage rate testing

  1. Face-Sealing Butterfly Valve

    Science.gov (United States)

    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.

  2. GIANT PROSTHETIC VALVE THROMBUS

    Directory of Open Access Journals (Sweden)

    Prashanth Kumar

    2015-04-01

    Full Text Available Mechanical prosthetic valves are predisposed to bleeding, thrombosis & thromboembolic complications. Overall incidence of thromboembolic complications is 1% per year who are on oral anticoagulants, whereas bleeding complications incidence is 0.5% to 6.6% per year. 1, 2 Minimization of Scylla of thromboembolic & Charybdis of bleeding complication needs a balancing act of optimal antithrombotic therapy. We are reporting a case of middle aged male patient with prosthetic mitral valve presenting in heart failure. Patient had discontinued anticoagulants, as he had subdural hematoma in the past. He presented to our institute with a giant prosthetic valve thrombus.

  3. Experimental and analytical studies on waterhammer generated by the closing of check valves

    International Nuclear Information System (INIS)

    Huet, J.L.; Garcia, J.L.; Coppolani, P.; Ziegler, B.

    1987-01-01

    A double-guillotine rupture on a water line upstream from a check valve generates a severe transient between the check valve and the pressure vessel on the downstream side. Successively following phenomena occur: - decrease then reversal of the flow, - closing of the check valve with impact of the plug on its seat, - waterhammer propagating in the pipe downstream from the check valve. The COMMISARIAT A L'ENERGIE ATOMIQUE (C.E.A.) FRAMATOME and ELECTRICITE DE FRANCE (E.D.F.) have undertaken a joint program in order to: - investigate the behavior uf the check valve in the event of a sudden closure, - evaluate the pressure and flow transient in the line. The program includes: - full scale tests in two loops, CLAUDIA (C.E.A.) and ECLAIR (E.D.F.), - analytical studies in order to qualify the calculation codes. This paper describes the experimental program and presents the analysis results for a benchmark test

  4. Valve monitoring ITI-MOVATS

    International Nuclear Information System (INIS)

    Moureau, S.

    1993-01-01

    ITI-MOVATS provides a wide range of test devices to monitor the performance of valves: motor operated gate or globe valve, butterfly valve, air operated valve, and check valve. The ITI-MOVATS testing equipment is used in the following three areas: actuator setup/baseline testing, periodic/post-maintenance testing, and differential pressure testing. The parameters typically measured with the MOVATS diagnostic system as well as the devices used to measure them are described. (Z.S.)

  5. Bioprosthetic Valve Fracture to Facilitate Transcatheter Valve-in-Valve Implantation.

    Science.gov (United States)

    Allen, Keith B; Chhatriwalla, Adnan K; Cohen, David J; Saxon, John T; Aggarwal, Sanjeev; Hart, Anthony; Baron, Suzanne; Davis, J Russell; Pak, Alex F; Dvir, Danny; Borkon, A Michael

    2017-11-01

    Valve-in-valve transcatheter aortic valve replacement is less effective in small surgical bioprostheses. We evaluated the feasibility of bioprosthetic valve fracture with a high-pressure balloon to facilitate valve-in-valve transcatheter aortic valve replacement. In vitro bench testing on aortic tissue valves was performed on 19-mm and 21-mm Mitroflow (Sorin, Milan, Italy), Magna and Magna Ease (Edwards Lifesciences, Irvine, CA), Trifecta and Biocor Epic (St. Jude Medical, Minneapolis, MN), and Hancock II and Mosaic (Medtronic, Minneapolis, MN). High-pressure balloons Tru Dilation, Atlas Gold, and Dorado (C.R. Bard, Murray Hill, NJ) were used to determine which valves could be fractured and at what pressure fracture occurred. Mitroflow, Magna, Magna Ease, Mosaic, and Biocor Epic surgical valves were successfully fractured using high-pressures balloon 1 mm larger than the labeled valve size whereas Trifecta and Hancock II surgical valves could not be fractured. Only the internal valve frame was fractured, and the sewing cuff was never disrupted. Manufacturer's rated burst pressures for balloons were exceeded, with fracture pressures ranging from 8 to 24 atmospheres depending on the surgical valve. Testing further demonstrated that fracture facilitated the expansion of previously constrained, underexpanded transcatheter valves (both balloon and self-expanding) to the manufacturer's recommended size. Bench testing demonstrates that the frame of most, but not all, bioprosthetic surgical aortic valves can be fractured using high-pressure balloons. The safety of bioprosthetic valve fracture to optimize valve-in-valve transcatheter aortic valve replacement in small surgical valves requires further clinical investigation. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  6. System for remotely servicing a top loading captive ball valve

    International Nuclear Information System (INIS)

    Berry, S.M.; Porter, M.L.

    1996-01-01

    An attachment for facilitating servicing of a valve is disclosed including: an assembly composed of a valve seat defining a flow path, a flow control member movable relative to the valve seat for blocking or unblocking the valve seat, and a control device including a stem coupled to the flow control member and operable for moving the flow control member relative to the valve se housing for receiving the assembly, the housing having an opening via which the assembly can be removed from, and installed in, the housing, and the housing having a plurality of threaded studs which surround the opening and project away from the housing; a valve housing cover for closing and sealing the opening in the housing, the cover having a first bore for passage of the stem of the control device when the assembly is installed in the housing and a plurality of second bores each located for passage of a respective stud when the cover closes the opening in the housing. A plurality of threaded nuts are engageable with the studs for securing the cover to the housing when the cover closes the opening in the housing, wherein the attachment comprises: a plurality of nut guide devices removable from the housing and each operatively associated with a respective stud for retaining a respective nut and guiding the respective nut into alignment with the respective stud to enable the respective nut to be rotated into engagement with the respective stud; and aligning the nut guide devices with the studs. 7 figs

  7. Pulmonary valve stenosis

    Science.gov (United States)

    ... surgery - discharge Images Heart valves References Carabello BA. Valvular heart disease. In: Goldman L, Schafer AI, eds. Goldman's Cecil ... Saunders; 2016:chap 69. Otto CM, Bownow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ...

  8. Mitral valve regurgitation

    Science.gov (United States)

    ... and dentist if you have a history of heart valve disease or congenital heart disease before treatment. Some people ... the middle Heart, front view References Carabello BA. Valvular heart disease. In: Goldman L, Schafer AI, eds. Goldman-Cecil ...

  9. Aortic Valve Disease

    Science.gov (United States)

    ... team will discuss with you the advantages and disadvantages of both valve types. Regardless of which type ... Diagnosis and Treatment Options Recovery Questions for Your Doctor Will my condition ever get better without treatment? ...

  10. Dry product valve

    International Nuclear Information System (INIS)

    Greaves, James D.

    1984-01-01

    This invention provides a system for delivering particulate radioactive or other toxic wastes to a container in which they can be solidified. The system includes a set of valves that prevent the escape of dusty materials to the atmosphere

  11. Ball check valve

    International Nuclear Information System (INIS)

    Bevilacqua, F.

    1978-01-01

    A pressurized nuclear reactor having an instrument assembly sheathed in a metallic tube which is extended vertically upward into the reactor core by traversing a metallic guide tube which is welded to the wall of the vessel is described. Sensors in each instrument assembly are connected to instruments outside the vessel to manifest the conditions within the core. Each instrument assembly probe is moved into position within a metallic guide channel. The guide channel penetrates the wall of the vessel and forms part of the barrier to the environment within the pressure vessel. Each channel includes a ball check valve which is opened by the instrument assembly probe when the probe passes through the valve. A ball valve element is moved from its seat by the probe to a position lateral of the bore of the channel and is guided to its seat along a sloped path within the valve body when the probe is removed. 5 claims, 3 figures

  12. Summer season | Cafeteria closures

    CERN Multimedia

    2013-01-01

    Please note the following cafeteria closures over the summer season: Bldg. 54 closed from 29/07/2013 to 06/09/2013. Bldg. 13: closed from 13/07/2013 to 06/09/2013. Restaurant No. 2, table service (brasserie and restaurant): closed from 01/08/2013 to 06/09/2013. Bldg. 864: closed from 29/07/2013 to 06/09/2013. Bldg. 865: closed from 29/07/2013 to 06/09/2013.

  13. Valve for gas centrifuges

    Science.gov (United States)

    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.

  14. Coanda effect in valves

    Directory of Open Access Journals (Sweden)

    Uruba Václav

    2017-01-01

    Full Text Available Coanda effect takes place in flow within valves diffuser for certain conditions. The valve plug in half-closed position forms wall-jet, which could be stable or instable, depending on geometry and other conditions. This phenomenon was subject of experimental study using time-resolved PIV technique. For the acquired data analysis the special spatio-temporal methods have been used.

  15. Overview of Prevention for Water Hammer by Check Valve Action in Nuclear Reactor

    International Nuclear Information System (INIS)

    Kim, Dayong; Yoon, Hyungi; Seo, Kyoungwoo; Kim, Seonhoon

    2016-01-01

    Water hammer can cause serious damage to pumping system and unexpected system pressure rise in the pipeline. In nuclear reactor, water hammer can influence on the integrity of safety related system. Water hammer in nuclear reactor have been caused by voiding in normally water-filled lines, steam condensation line containing both steam and water, as well as by rapid check valve action. Therefore, this study focuses on the water hammer by check valve among the sources of water hammer occurrence and suggests proper methodology for check valve type selection against water hammer. This study focuses on the water hammer by check valve action among the sources of water hammer occurrence and suggests proper methodology for check valve type selection against water hammer. If the inadvertent pump trip or pipe rupture in high velocity and pressure pipe is predicted, the fast response check valve such as tiled disc, dual disc and nozzle check valve should be installed in the system. If the inadvertent pump trip or pipe rupture in very high velocity and pressure pipe and excessively large revered flow velocity are predicted, the very slowly closing check valve such as controlled closure check valve should be installed in the system

  16. Overview of Prevention for Water Hammer by Check Valve Action in Nuclear Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dayong; Yoon, Hyungi; Seo, Kyoungwoo; Kim, Seonhoon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    Water hammer can cause serious damage to pumping system and unexpected system pressure rise in the pipeline. In nuclear reactor, water hammer can influence on the integrity of safety related system. Water hammer in nuclear reactor have been caused by voiding in normally water-filled lines, steam condensation line containing both steam and water, as well as by rapid check valve action. Therefore, this study focuses on the water hammer by check valve among the sources of water hammer occurrence and suggests proper methodology for check valve type selection against water hammer. This study focuses on the water hammer by check valve action among the sources of water hammer occurrence and suggests proper methodology for check valve type selection against water hammer. If the inadvertent pump trip or pipe rupture in high velocity and pressure pipe is predicted, the fast response check valve such as tiled disc, dual disc and nozzle check valve should be installed in the system. If the inadvertent pump trip or pipe rupture in very high velocity and pressure pipe and excessively large revered flow velocity are predicted, the very slowly closing check valve such as controlled closure check valve should be installed in the system.

  17. Hemodynamics in the Valsalva sinuses after transcatheter aortic valve implantation (TAVI).

    Science.gov (United States)

    Ducci, Andrea; Tzamtzis, Spyridon; Mullen, Michael J; Burriesci, Gaetano

    2013-09-01

    The study aim was to assess, in vitro, the hemodynamic modifications produced by transcatheter valves in the Valsalva sinuses, by mean of phase-resolved particle image velocimetry (PIV) measurements. Flow measurements were performed on a glass mock aortic root that included three polymeric valve leaflets, before and after the implantation of a Medtronic CoreValve device and of an Edwards SAPIEN valve. All experiments were carried out in a hydro-mechanical cardiovascular pulse duplicator system (Vivitro Superpump System SP3891) that reproduced physiologically equivalent pressures and flow rates conforming to the requirements of the standard ISO 5840:2005. The flow dynamics, before and after implantation of the two prosthetic devices, was characterized on the basis of phase-resolved velocity field and viscous shear rate measurements. Direct comparison indicated that both transcatheter valves determined a significant variation of flow during the early stages of valve opening and during valve closure. In general, the presence of the two valve implants significantly reduced the flow activity in the Valsalva sinuses, promoting regions of stagnation at their base. The reduction in flow in the Valsalva sinuses could be associated with the higher incidence of ischemic events reported after transcatheter heart valve implantation.

  18. RELAP-7 Closure Correlations

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Ling [Idaho National Lab. (INL), Idaho Falls, ID (United States); Berry, R. A. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Martineau, R. C. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Andrs, D. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zhang, H. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Hansel, J. E. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Sharpe, J. P. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Johns, Russell C. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-04-01

    The RELAP-7 code is the next generation nuclear reactor system safety analysis code being developed at the Idaho National Laboratory (INL). The code is based on the INL’s modern scientific software development framework, MOOSE (Multi-Physics Object Oriented Simulation Environment). The overall design goal of RELAP-7 is to take advantage of the previous thirty years of advancements in computer architecture, software design, numerical integration methods, and physical models. The end result will be a reactor systems analysis capability that retains and improves upon RELAP5’s and TRACE’s capabilities and extends their analysis capabilities for all reactor system simulation scenarios. The RELAP-7 code utilizes the well-posed 7-equation two-phase flow model for compressible two-phase flow. Closure models used in the TRACE code has been reviewed and selected to reflect the progress made during the past decades and provide a basis for the colure correlations implemented in the RELAP-7 code. This document provides a summary on the closure correlations that are currently implemented in the RELAP-7 code. The closure correlations include sub-grid models that describe interactions between the fluids and the flow channel, and interactions between the two phases.

  19. Urethrovaginal fistula closure.

    Science.gov (United States)

    Clifton, Marisa M; Goldman, Howard B

    2017-01-01

    In the developed world, urethrovaginal fistulas are most the likely the result of iatrogenic injury. These fistulas are quite rare. Proper surgical repair requires careful dissection and tension-free closure. The objective of this video is to demonstrate the identification and surgical correction of an urethrovaginal fistula. The case presented is of a 59-year-old woman with a history of pelvic organ prolapse and symptomatic stress urinary incontinence who underwent vaginal hysterectomy, anterior colporrhaphy, posterior colporrhaphy, and synthetic sling placement. Postoperatively, she developed a mesh extrusion and underwent sling excision. After removal of her synthetic sling, she began to experience continuous urinary incontinence. Physical examination and cystourethroscopy demonstrated an urethrovaginal fistula at the midurethra. Options were discussed and the patient wished to undergo transvaginal fistula repair. The urethrovaginal fistula was intubated with a Foley catheter. The fistula tract was isolated and removed. The urethra was then closed with multiple tension-free layers. This video demonstrates several techniques for identifying and subsequently repairing an urethrovaginal fistula. Additionally, it demonstrates the importance of tension-free closure. Urethrovaginal fistulas are rare. They should be repaired with careful dissection and tension-free closure.

  20. Improvement of tricuspid regurgitation after transcatheter ASD closure in older patients.

    Science.gov (United States)

    Chen, L; Shen, J; Shan, X; Wang, F; Kan, T; Tang, X; Zhao, X; Qin, Y

    2017-07-19

    Adult patients with undiagnosed atrial septal defect (ASD) may have right heart cavity enlargement and functional tricuspid valve insufficiency. Moderate or more severe tricuspid regurgitation has been associated with a worse prognosis, and more serious complications are typically seen in older patients. This study aimed to evaluate the improvement in functional tricuspid regurgitation and heart geometry after transcatheter ASD closure in older patients. The data of 111 patients over 60 years of age with moderate or severe tricuspid regurgitation before ASD closure were analyzed. At the 1‑month and 6‑month follow-up after closure, both tricuspid regurgitation jet area and right atrial volume decreased significantly. Right ventricular volume decreased 1 month after closure, showing a further decrease at the end of the 6‑month follow-up. However, 24 patients (21.6%) still had persistent severe tricuspid regurgitation after the procedure. Multivariate analysis revealed that patient age at ASD closure and pulmonary artery systolic pressure determined by echocardiography before closure were predictors of persistent tricuspid regurgitation after closure. Transcatheter ASD closure in older patients could significantly decrease tricuspid regurgitation and improve right heart geometry.

  1. Predictors of transient left ventricular dysfunction following transcatheter patent ductus arteriosus closure in pediatric age.

    Science.gov (United States)

    Agha, Hala Mounir; Hamza, Hala S; Kotby, Alyaa; Ganzoury, Mona E L; Soliman, Nanies

    2017-10-01

    To evaluate the left ventricular function before and after transcatheter percutaneous patent ductus arteriosus (PDA) closure, and to identify the predictors of myocardial dysfunction post-PDA closure if present. Transcatheter PDA closure; conventional, Doppler, and tissue Doppler imaging; and speckle tracking echocardiography. To determine the feasibility and reliability of tissue Doppler and myocardial deformation imaging for evaluating myocardial function in children undergoing transcatheter PDA closure. Forty-two children diagnosed with hemodynamically significant PDA underwent percutaneous PDA closure. Conventional, Doppler, and tissue Doppler imaging, and speckle-derived strain rate echocardiography were performed at preclosure and at 48 hours, 1 month, and 6 months postclosure. Tissue Doppler velocities of the lateral and septal mitral valve annuli were obtained. Global and regional longitudinal peak systolic strain values were determined using two-dimensional speckle tracking echocardiography. The median age of the patients was 2 years and body weight was 15 kg, with the mean PDA diameter of 3.11 ± 0.99 mm. M-mode measurements (left ventricular end diastolic diameter, left atrium diameter to aortic annulus ratio, ejection fraction, and shortening fraction) reduced significantly early after PDA closure ( p  closure causes a significant decrease in left ventricular performance early after PDA closure, which recovers completely within 1 month. Preclosure global longitudinal strain can be a predictor of postclosure myocardial dysfunction.

  2. A prospective multicenter clinical feasibility study of a new automatic speaking valve for postlaryngectomy voice rehabilitation

    NARCIS (Netherlands)

    Lansaat, L.; de Kleijn, B. J.; Hilgers, F. J. M.; van der Laan, B. F. A. M.; van den Brekel, M. W. M.

    Evaluation of short- and long-term clinical feasibility and exploration of limitations and advantages of a new automatic speaking valve (ASV) for laryngectomized patients with integrated HME, the Provox FreeHands FlexiVoice (FlexiVoice). This ASV not only enables automatic, but also manual closure

  3. RELAP5/MOD3.3 assessment against MSIV closure events in Krsko NPP

    International Nuclear Information System (INIS)

    Parzer, I.

    2002-01-01

    The paper presents RELAP5/MOD3.3 analysis of two abnormal events occurred in Krsko NPP originating from sudden closure of Main Steam Isolation Valve (MSIV). Both events occurred before the SG replacement in 2000, the first one in September 1995 and the second one in January 1997. Valuable plant data were obtained from real plant transients and the RELAP5 code assessment was performed. Recently the last frozen version RELAP5/MOD3.3 has been released, before merging with another best-estimate thermalhydraulic system code TRAC into an integrated code. It is thus of utmost importance to assess models built in RELAP5 code against real plant transients before the code merger. A full twoloop plant model, developed at Jozef Stefan Institute (JSI), has been used for the analyses. The model includes old Westinghouse D4 type steam generators (SGs) with assumed 18% Utubes plugged in both steam generators. In the first case a malfunction in the MSIV in SG-1 caused inadvertent valve closure, while in the second case the valve stem has been broken in the SG-2, which also caused sudden valve closure.(author)

  4. Role of vortices in cavitation formation in the flow across a mechanical heart valve.

    Science.gov (United States)

    Li, Chi-Pei; Lu, Po-Chien; Liu, Jia-Shing; Lo, Chi-Wen; Hwang, Ned H

    2008-07-01

    Cavitation occurs during mechanical heart valve closure when the local pressure drops below vapor pressure. The formation of stable gas bubbles may result in gaseous emboli, and secondarily cause transient ischemic attacks or strokes. It is noted that instantaneous valve closure, occluder rebound and high-speed leakage flow generate vortices that promote low-pressure regions in favor of stable bubble formation; however, to date no studies have been conducted for the quantitative measurement and analysis of these vortices. A Björk-Shiley Monostrut (BSM) monoleaflet valve was placed in the mitral position of a pulsatile mock circulatory loop. Particle image velocimetry (PIV) and pico coulomb (PCB) pressure measurements were applied. Flow field measurements were carried out at t = -5, -3, -1, -0.5, 0 (valve closure), 0.3, 0.5, 0.75, 1.19, 1.44, 1.69, 1.94, 2, 2.19, 2.54, 2.79, 3.04, 3.29, 3.54, 5 and 10 ms. The vortices were quantitatively analyzed using the Rankine vortex model. A single counter-clockwise vortex was The instantaneous formation of cavitation bubbles at mechanical heart valve (MHV) closure, which subsequently damage blood cells and valve integrity, is a well-known and widely studied phenomenon (1-4). Contributing factors seem to include the water-hammer, squeeze flow and Venturi effects, all of which are short-lived. Both, Dauzat et al. (5) and Sliwka et al. (6) have detected high-intensity transient signals (HITS) with transcranial Doppler ultrasound in the carotid and cerebral arteries of MHV recipients, while Deklunder (7) observed clinical occurrences of cerebral gas emboli that were not seen with bioprosthetic valves. These detected over the major orifice, while a pair of counter-rotating vortices was found over the minor orifice. Velocity profiles were consistent with Rankine vortices. The vortex strength and magnitude of the pressure drop peaked shortly after initial occluder-housing impact and rapidly decreased after 0.5 ms, indicating viscous

  5. Transcatheter Aortic Valve Replacement for Degenerative Bioprosthetic Surgical Valves

    DEFF Research Database (Denmark)

    Dvir, Danny; Webb, John; Brecker, Stephen

    2012-01-01

    Transcatheter aortic valve-in-valve implantation is an emerging therapeutic alternative for patients with a failed surgical bioprosthesis and may obviate the need for reoperation. We evaluated the clinical results of this technique using a large, worldwide registry....

  6. NRC valve performance test program - check valve testing

    International Nuclear Information System (INIS)

    Jeanmougin, N.M.

    1987-01-01

    The Valve Performance Test Program addresses the current requirements for testing of pressure isolation valves (PIVs) in light water reactors. Leak rate monitoring is the current method used by operating commercial power plants to survey the condition of their PIVs. ETEC testing of three check valves (4-inch, 6-inch, and 12-inch nominal diameters) indicates that leak rate testing is not a reliable method for detecting impending valve failure. Acoustic emission monitoring of check valves shows promise as a method of detecting loosened internals damage. Future efforts will focus on evaluation of acoustic emission monitoring as a technique for determining check valve condition. Three gate valves also will be tested to evaluate whether the check valve results are applicable to gate type PIVs

  7. Nevada Test Site closure program

    International Nuclear Information System (INIS)

    Shenk, D.P.

    1994-08-01

    This report is a summary of the history, design and development, procurement, fabrication, installation and operation of the closures used as containment devices on underground nuclear tests at the Nevada Test Site. It also addresses the closure program mothball and start-up procedures. The Closure Program Document Index and equipment inventories, included as appendices, serve as location directories for future document reference and equipment use

  8. MNC Subsidiary Closure

    DEFF Research Database (Denmark)

    de Faria, Pedro; Sofka, Wolfgang; Torres Preto, Miguel

    2013-01-01

    We investigate the consequences of MNC subsidiary closures for employees who lose their jobs. We ask to what degree the foreign knowledge that they were exposed to is valued in their new job. We argue theoretically that this foreign knowledge is both valuable and not readily available in the host...... country but is also distant and therefore difficult to absorb. We predict an inverse u-shaped relationship between the exposure to foreign knowledge and the salary in the new job. We empirically support our predictions for a sample of almost 140,000 affected employees in Portugal from 2002 to 2009....

  9. Check valves aging assessment

    International Nuclear Information System (INIS)

    Haynes, H.D.

    1991-01-01

    In support of the NRC Nuclear Plant Aging Research (NPAR) program, the Oak Ridge National Laboratory (ORNL) has carried out an assessment of several check value diagnostic monitoring methods, in particular, those based on measurements of acoustic emission, ultrasonics, and magnetic flux. The evaluations have focussed on the capabilities of each method to provide information useful in determining check valve aging and service wear effects, check valve failures, and undesirable operating modes. This paper describes the benefits and limitations associated with each method and includes recent laboratory and field test data, including data obtained from the vendors who recently participated in a comprehensive series of tests directed by a nuclear industry users group. In addition, as part of the ORNL Advanced Diagnostic Engineering Research and Development Center (ADEC), two novel nonintrusive monitoring methods were developed that provide several unique capabilities. These methods, based on external ac- an dc-magnetic monitoring are also described. None of the examined methods could, by themselves, monitor both the instantaneous position and motion of check valve internals and valve leakage; however, the combination of acoustic emission monitoring with one of the other methods provides the means to determine vital check valve operational information

  10. The patient inflating valve in anaesthesia and resuscitation breathing systems.

    Science.gov (United States)

    Fenton, P M; Bell, G

    2013-03-01

    Patient inflating valves combined with self-inflating bags are known to all anaesthetists as resuscitation devices and are familiar as components of draw-over anaesthesia systems. Their variants are also commonplace in transfer and home ventilators. However, the many variations in structure and function have led to difficulties in their optimal use, definition and classification. After reviewing the relevant literature, we defined a patient inflating valve as a one-way valve that closes an exit port to enable lung inflation, also permitting exhalation and spontaneous breathing, the actions being automatic. We present a new classification based on the mechanism of valve opening/closure; namely elastic recoil of a flexible flap/diaphragm, sliding spindle opened by a spring/magnet or a hollow balloon collapsed by external pressure. The evolution of these valves has been driven by the difficulties documented in critical incidents, which we have used along with information from modern International Organization for Standardization standards to identify 13 ideal properties, the top six of which are non-jamming, automatic, no bypass effect, no rebreathing or air entry at patient end, low resistance, robust and easy to service. The Ambu and the Laerdal valves have remained popular due to their simplicity and reliability. Two new alternatives, the Fenton and Diamedica valves, offer the benefits of location away from the patient while retaining a small functional dead space. They also offer the potential for greater use of hybrid continuous flow/draw-over systems that can operate close to atmospheric pressure. The reliable application of positive end-expiratory pressure/continuous positive airway pressure remains a challenge.

  11. Aortic valve replacement and the stentless Freedom SOLO valve

    NARCIS (Netherlands)

    Wollersheim, L.W.L.M.

    2016-01-01

    Aortic valve stenosis has become the most prevalent valvular heart disease in Europe and North America, and is generally caused by age-related calcification of the aortic valve. For most patients, severe symptomatic aortic stenosis needs effective mechanical relief in the form of valve replacement

  12. Comparative study of Butterfly valves

    International Nuclear Information System (INIS)

    Galmes Belmonte, F.B.

    1998-01-01

    This work tries to justify the hydrodynamic butterfly valves performance, using the EPRI tests, results carried out in laboratory and in situ. This justification will be possible if: - The valves to study are similar - Their performance is calculated using EPRI's methodology Looking for this objective, the elements of the present work are: 1. Brief EPRI butterfly valve description it wild provide the factors which are necessary to define the butterfly valves similarity. 2. EPRI tests description and range of validation against test data definition. 3. Description of the spanish butterfly analyzed valves, and comparison with the EPRI performance results, to prove that this valves are similar to the EPRI test valves. In this way, it will not be necessary to carry out particular dynamic tests on the spanish valves to describe their hydrodynamic performance. (Author)

  13. A symmetric safety valve

    International Nuclear Information System (INIS)

    Burtraw, Dallas; Palmer, Karen; Kahn, Danny

    2010-01-01

    How to set policy in the presence of uncertainty has been central in debates over climate policy. Concern about costs has motivated the proposal for a cap-and-trade program for carbon dioxide, with a 'safety valve' that would mitigate against spikes in the cost of emission reductions by introducing additional emission allowances into the market when marginal costs rise above the specified allowance price level. We find two significant problems, both stemming from the asymmetry of an instrument that mitigates only against a price increase. One is that most important examples of price volatility in cap-and-trade programs have occurred not when prices spiked, but instead when allowance prices collapsed. Second, a single-sided safety valve may have unintended consequences for investment. We illustrate that a symmetric safety valve provides environmental and welfare improvements relative to the conventional one-sided approach.

  14. Chernobyl: closure by 2000

    International Nuclear Information System (INIS)

    Anon.

    1995-01-01

    Discussions on the future of the Chernobyl nuclear plant between the Ukrainian government, the Group of Seven Industrial nations (GT) and the European Union (EU) are summarized. At the G7 meeting, a timetable for the closure of the entire station by 2000 was presented by Ukrainian officials. The timetable depends on financial commitments from Western governments. Without these, the project would take 10 to 15 years. Following this meeting, which took place on 16-17th May 1995. EU finance ministers authorized release of a ECU 85 million loan. On 23 May, the European Parliament's Committee on Research, Technology and Energy held a public hearing on the Chernobyl station. The primary topic was a feasibility study on the clean-up of Chernobyl 4 and plans for the sarcophagus. Other matters discussed included the effect of the delays and indecision in settling the plants's future. Safety improvements being made to other RBMKs were not being carried out at Chernobyl because of the expected closure. The replacement of the power now supplied to the Ukraine by the Chernobyl reactors is also an issue. The solution favoured by the Ukraine is to being on-line three VVER-1000s that are currently close to completion. Western governments find this solution difficult to accept, however. (UK)

  15. The Double-Orifice Valve Technique to Treat Tricuspid Valve Incompetence.

    Science.gov (United States)

    Hetzer, Roland; Javier, Mariano; Delmo Walter, Eva Maria

    2016-01-01

    A straightforward tricuspid valve (TV) repair technique was used to treat either moderate or severe functional (normal valve with dilated annulus) or for primary/organic (Ebstein's anomaly, leaflet retraction/tethering and chordal malposition/tethering, with annular dilatation) TV incompetence, and its long-term outcome assessed. A double-orifice valve technique was employed in 91 patients (mean age 52.6 ± 23.2 years; median age 56 years; range: 0.6-82 years) with severe tricuspid regurgitation. Among the patients, three had post-transplant iatrogenic chordal rupture, five had infective endocarditis, 11 had mitral valve insufficiency, 23 had Ebstein's anomaly, and 47 had isolated severe TV incompetence. The basic principle was to reduce the distance between the coapting leaflets, wherein the most mobile leaflet could coapt to the opposite leaflet, by creating two orifices, ensuring valve competence. The TV repair was performed through a median sternotomy or right anterior thoracotomy in the fifth intercostal space under cardiopulmonary bypass. The degree and extent of creating a double-valve orifice was determined by considering the minimal body surface area (BSA)-related acceptable TV diameter. Repair was accomplished by passing pledgeted mattress sutures from the middle of the true anterior annulus to a spot on the opposite septal annulus, located approximately two-thirds of the length of the septal annulus to avoid injury to the bundle of His. The annular apposition divides the TV into a larger anterior and a smaller posterior orifices, enabling valve closure, on both sides. In adults, the diameter of the anterior valve orifice should be 23-25 mm, and the posterior orifice 15-18 mm; thus, the total valve orifice area is 5-6 cm2. In children, the total valve orifice should be a standard deviation of 1.7 mm for a BSA of 1.0m2. During a mean follow up of 8.7 ± 1.34 years (median 10 years; range: 1.5-25.9 years) there have been no reoperations for TV insufficiency

  16. Tight closure and vanishing theorems

    International Nuclear Information System (INIS)

    Smith, K.E.

    2001-01-01

    Tight closure has become a thriving branch of commutative algebra since it was first introduced by Mel Hochster and Craig Huneke in 1986. Over the past few years, it has become increasingly clear that tight closure has deep connections with complex algebraic geometry as well, especially with those areas of algebraic geometry where vanishing theorems play a starring role. The purpose of these lectures is to introduce tight closure and to explain some of these connections with algebraic geometry. Tight closure is basically a technique for harnessing the power of the Frobenius map. The use of the Frobenius map to prove theorems about complex algebraic varieties is a familiar technique in algebraic geometry, so it should perhaps come as no surprise that tight closure is applicable to algebraic geometry. On the other hand, it seems that so far we are only seeing the tip of a large and very beautiful iceberg in terms of tight closure's interpretation and applications to algebraic geometry. Interestingly, although tight closure is a 'characteristic p' tool, many of the problems where tight closure has proved useful have also yielded to analytic (L2) techniques. Despite some striking parallels, there had been no specific result directly linking tight closure and L∼ techniques. Recently, however, the equivalence of an ideal central to the theory of tight closure was shown to be equivalent to a certain 'multiplier ideal' first defined using L2 methods. Presumably, deeper connections will continue to emerge. There are two main types of problems for which tight closure has been helpful: in identifying nice structure and in establishing uniform behavior. The original algebraic applications of tight closure include, for example, a quick proof of the Hochster-Roberts theorem on the Cohen-Macaulayness of rings of invariants, and also a refined version of the Brianqon-Skoda theorem on the uniform behaviour of integral closures of powers of ideals. More recent, geometric

  17. Valve spindle gland

    International Nuclear Information System (INIS)

    Burda, Z.; Harazim, A.; Kerlin, K.

    1979-01-01

    A gland is proposed of the valve spindle designed for radioactive or otherwise harmful media, such as in nuclear power plant primary circuits. The gland is installed in the valve cover and consists of a primary and a secondary part and of a gland case partitioning the gland space into two chambers. The bottom face of the gland case is provided with a double-sided collar for controlling the elements of the bottom primary gland while the top face is provided with a removable flange. (M.S.)

  18. Building valve amplifiers

    CERN Document Server

    Jones, Morgan

    2013-01-01

    Building Valve Amplifiers is a unique hands-on guide for anyone working with tube audio equipment--as an electronics hobbyist, audiophile or audio engineer. This 2nd Edition builds on the success of the first with technology and technique revisions throughout and, significantly, a major new self-build project, worked through step-by-step, which puts into practice the principles and techniques introduced throughout the book. Particular attention has been paid to answering questions commonly asked by newcomers to the world of the valve, whether audio enthusiasts tackling their first build or

  19. Valve thrombosis following transcatheter aortic valve implantation: a systematic review.

    Science.gov (United States)

    Córdoba-Soriano, Juan G; Puri, Rishi; Amat-Santos, Ignacio; Ribeiro, Henrique B; Abdul-Jawad Altisent, Omar; del Trigo, María; Paradis, Jean-Michel; Dumont, Eric; Urena, Marina; Rodés-Cabau, Josep

    2015-03-01

    Despite the rapid global uptake of transcatheter aortic valve implantation, valve trombosis has yet to be systematically evaluated in this field. The aim of this study was to determine the clinical characteristics, diagnostic criteria, and treatment outcomes of patients diagnosed with valve thrombosis following transcatheter aortic valve implantation through a systematic review of published data. Literature published between 2002 and 2012 on valve thrombosis as a complication of transcatheter aortic valve implantation was identified through a systematic electronic search. A total of 11 publications were identified, describing 16 patients (mean age, 80 [5] years, 65% men). All but 1 patient (94%) received a balloon-expandable valve. All patients received dual antiplatelet therapy immediately following the procedure and continued to take either mono- or dual antiplatelet therapy at the time of valve thrombosis diagnosis. Valve thrombosis was diagnosed at a median of 6 months post-procedure, with progressive dyspnea being the most common symptom. A significant increase in transvalvular gradient (from 10 [4] to 40 [12] mmHg) was the most common echocardiographic feature, in addition to leaflet thickening. Thrombus was not directly visualized with echocardiography. Three patients underwent valve explantation, and the remaining received warfarin, which effectively restored the mean transvalvular gradient to baseline within 2 months. Systemic embolism was not a feature of valve thrombosis post-transcatheter aortic valve implantation. Although a rare, yet likely under-reported complication of post-transcatheter aortic valve implantation, progressive dyspnea coupled with an increasing transvalvular gradient on echocardiography within the months following the intervention likely signifies valve thrombosis. While direct thrombus visualization appears difficult, prompt initiation of oral anticoagulation therapy effectively restores baseline valve function. Copyright © 2014

  20. Platypnea-Orthodeoxia Syndrome after Transcatheter Aortic Valve Implantation

    Directory of Open Access Journals (Sweden)

    Andrew K. Roy

    2016-01-01

    Full Text Available Progressive dyspnea and hypoxaemia in the subacute phase after transcatheter aortic valve implantation (TAVI are uncommon and warrant immediate assessment of valve and prosthesis leaflet function to exclude thrombosis, as well as investigation for other causes related to the procedure, such as left ventricular dysfunction, pulmonary embolism, and respiratory sepsis. In this case, we report the observation of a patient presenting two weeks after TAVI with arterial hypoxaemia in an upright position, relieved by lying flat, and coupled with an intracardiac shunt detected on echocardiography in the absence of pulmonary hypertension, raising the suspicion of Platypnea-Orthodeoxia Syndrome (POS. Invasive intracardiac haemodynamic assessment showed a significant right-to-left shunt (Qp/Qs = 0.74, which confirmed the diagnosis, with subsequent closure of the intracardiac defect resulting in immediate relief of symptoms and hypoxaemia. To our knowledge, this is the first reported case of an interatrial defect and shunt causing Platypnea-Orthodeoxia Syndrome after transcatheter aortic valve implantation, resolved by percutaneous device closure.

  1. Cavitation problems in sodium valves

    International Nuclear Information System (INIS)

    Elie, X.

    1976-01-01

    Cavitation poses few problems for sodium valves, in spite of the fact that the loops are not pressurized. This is no doubt due to the low flow velocities in the pipes. For auxiliary loop valves we are attempting to standardize performances with respect to cavitation. For economic reasons cavitation thresholds are approached with large diameter valves. (author)

  2. Transcatheter aortic valve implantation in failed bioprosthetic surgical valves

    DEFF Research Database (Denmark)

    Dvir, Danny; Webb, John G; Bleiziffer, Sabine

    2014-01-01

    for patients with structural valve deterioration; however, a comprehensive evaluation of survival after the procedure has not yet been performed. OBJECTIVE: To determine the survival of patients after transcatheter valve-in-valve implantation inside failed surgical bioprosthetic valves. DESIGN, SETTING......, stroke, and New York Heart Association functional class. RESULTS: Modes of bioprosthesis failure were stenosis (n = 181 [39.4%]), regurgitation (n = 139 [30.3%]), and combined (n = 139 [30.3%]). The stenosis group had a higher percentage of small valves (37% vs 20.9% and 26.6% in the regurgitation...... and combined groups, respectively; P = .005). Within 1 month following valve-in-valve implantation, 35 (7.6%) patients died, 8 (1.7%) had major stroke, and 313 (92.6%) of surviving patients had good functional status (New York Heart Association class I/II). The overall 1-year Kaplan-Meier survival rate was 83...

  3. SAFETY SHUTOFF VALVE

    DEFF Research Database (Denmark)

    2010-01-01

    It is disclosed a shut-off valve which acts automatically and has a fully mechanical performance with respect to the loosing of the tower-shape part balance under the effect of the special acceleration Which is arisen from the quakes waves or serious vibrations, while such vibrations are mainly r...

  4. Heart valve surgery - discharge

    Science.gov (United States)

    ... ACC guideline for the management of patients with valvular heart disease: executive summary: a report of the American College ... Editorial team. Related MedlinePlus Health Topics Heart Surgery Heart Valve Diseases Browse the Encyclopedia A.D.A.M., Inc. ...

  5. Poppet valve tester

    Science.gov (United States)

    Tellier, G. F.

    1973-01-01

    Tester investigates fundamental factors affecting cyclic life and sealing performance of valve seats and poppets. Tester provides for varying impact loading of poppet against seat and rate of cycling, and controls amount and type of relative motion between sealing faces of seat and poppet. Relative motion between seat and poppet can be varied in three modes.

  6. Thermostatic Radiator Valve Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Dentz, Jordan [Advanced Residential Integrated Energy Solutions Collaborative, New York, NY (United States); Ansanelli, Eric [Advanced Residential Integrated Energy Solutions Collaborative, New York, NY (United States)

    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.

  7. Blocked Urethral Valves

    Science.gov (United States)

    ... if any damage has occurred to the upper urinary tract. Your pediatrician will consult with a pediatric nephrologist (kidney specialist) or nurologist, who may recommend surgery to remove the obstructing valves and prevent further infection or damage to the kidneys or urinary system. ...

  8. Transcatheter aortic valve implantation of the direct flow medical aortic valve with minimal or no contrast

    Energy Technology Data Exchange (ETDEWEB)

    Latib, Azeem, E-mail: alatib@gmail.com [Interventional Cardiology Unit, San Raffaele Scientific Institute and EMO-GVM Centro Cuore Columbus, Milan (Italy); Maisano, Francesco; Colombo, Antonio [Interventional Cardiology Unit, San Raffaele Scientific Institute and EMO-GVM Centro Cuore Columbus, Milan (Italy); Klugmann, Silvio [Azienda Ospedaliera Niguarda Ca Granda, Piazza Ospedale Maggiore 3, Milan (Italy); Low, Reginald; Smith, Thomas [University of California Davis, Davis, CA 95616 (United States); Davidson, Charles [Northwestern Memorial Hospital, Chicago, IL 60611 (United States); Harreld, John H. [Clinical Imaging Analytics, Guerneville, CA (United States); Bruschi, Giuseppe; DeMarco, Federico [Azienda Ospedaliera Niguarda Ca Granda, Piazza Ospedale Maggiore 3, Milan (Italy)

    2014-06-15

    The 18F Direct Flow Medical (DFM) THV has conformable sealing rings, which minimizes aortic regurgitation and permits full hemodynamic assessment of valve performance prior to permanent implantation. During the DISCOVER trial, three patients who were at risk for receiving contrast media, two due to severe CKD and one due to a recent hyperthyroid reaction to contrast, underwent DFM implantation under fluoroscopic and transesophageal guidance without aortography during either positioning or to confirm the final position. Valve positioning was based on the optimal angiographic projection as calculated by the pre-procedural multislice CT scan. Precise optimization of valve position was performed to minimize transvalve gradient and aortic regurgitation. Prior to final implantation, transvalve hemodynamics were assessed invasively and by TEE. The post-procedure mean gradients were 7, 10, 11 mm Hg. The final AVA by echo was 1.70, 1.40 and 1.68 cm{sup 2}. Total aortic regurgitation post-procedure was none or trace in all three patients. Total positioning and assessment of valve performance time was 4, 6, and 12 minutes. Contrast was only used to confirm successful percutaneous closure of the femoral access site. The total contrast dose was 5, 8, 12 cc. Baseline eGFR and creatinine was 28, 22, 74 mL/min/1.73 m{sup 2} and 2.35, 2.98, and 1.03 mg/dL, respectively. Renal function was unchanged post-procedure: eGFR = 25, 35, and 96 mL/min/1.73 m{sup 2} and creatinine = 2.58, 1.99, and 1.03 mg/dL, respectively. In conclusion, the DFM THV provides the ability to perform TAVI with minimal or no contrast. The precise and predictable implantation technique can be performed with fluoro and echo guidance.

  9. Airport Movement Area Closure Planner, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This SBIR research develops an automation tool improving temporary and permanent runway closure management. The Movement Area Closure Planner (MACP) provides airport...

  10. Tricuspid valve endocarditis

    Science.gov (United States)

    Hussain, Syed T.; Witten, James; Shrestha, Nabin K.; Blackstone, Eugene H.

    2017-01-01

    Right-sided infective endocarditis (RSIE) is less common than left-sided infective endocarditis (IE), encompassing only 5–10% of cases of IE. Ninety percent of RSIE involves the tricuspid valve (TV). Given the relatively small numbers of TVIE cases operated on at most institutions, the purpose of this review is to highlight and discuss the current understanding of IE involving the TV. RSIE and TVIE are strongly associated with intravenous drug use (IVDU), although pacemaker leads, defibrillator leads and vascular access for dialysis are also major risk factors. Staphylococcus aureus is the predominant causative organism in TVIE. Most patients with TVIE are successfully treated with antibiotics, however, 5–16% of RSIE cases eventually require surgical intervention. Indications and timing for surgery are less clear than for left-sided IE; surgery is primarily considered for failed medical therapy, large vegetations and septic pulmonary embolism, and less often for TV regurgitation and heart failure. Most patients with an infected prosthetic TV will require surgery. Concomitant left-sided IE has its own surgical indications. Earlier surgical intervention may potentially prevent further destruction of leaflet tissue and increase the likelihood of TV repair. Fortunately, TV debridement and repair can be accomplished in most cases, even those with extensive valve destruction, using a variety of techniques. Valve repair is advocated over replacement, particularly in IVDUs patients who are young, non-compliant and have a higher risk of recurrent infection and reoperation with valve replacement. Excising the valve without replacing, it is not advocated; it has been reported previously, but these patients are likely to be symptomatic, particularly in cases with septic pulmonary embolism and increased pulmonary vascular resistance. Patients with concomitant left-sided involvement have worse prognosis than those with RSIE alone, due predominantly to greater likelihood of

  11. MOVES: A knowledge-based system for maintenance planning for motor-operated valves

    International Nuclear Information System (INIS)

    Winter, M.

    1987-01-01

    Over the past several years, knowledge-based expert systems have emerged as an important part of the general research area known as artificial intelligence. This paper describes a cooperative effort between faculty members at Iowa State University and engineers at the Duane Arnold Energy Center [a 545-MW(electric) boiling water reactor operated by Iowa Electric Light and Power Company] to explore the development of an advisory system for valve maintenance planning. This knowledge-based program, known as Motor-Operated Valves Expert System (MOVES), has a data base that currently includes safety-related motor-operated valves (∼117 valves). Valve maintenance was selected as the subject for the expert system because of the importance of valves in nuclear plant and their impact of plant availability. MOVES is being developed using the microcomputer-(IBM compatible) based expert system tool INSIGHT2+. The authors have found that the project benefits both the university and the utility

  12. Closure report for N Reactor

    International Nuclear Information System (INIS)

    1994-01-01

    This report has been prepared to satisfy Section 3156(b) of Public Law 101-189 (Reports in Connection with Permanent Closures of Department of Energy Defense Nuclear Facilities), which requires submittal of a Closure Report to Congress by the Secretary of Energy upon the permanent cessation of production operations at a US Department of Energy (DOE) defense nuclear facility (Watkins 1991). This closure report provides: (1) A complete survey of the environmental problems at the facility; (2) Budget quality data indicating the cost of environmental restoration and other remediation and cleanup efforts at the facility; (3) A proposed cleanup schedule

  13. Closure report for N Reactor

    Energy Technology Data Exchange (ETDEWEB)

    1994-01-01

    This report has been prepared to satisfy Section 3156(b) of Public Law 101-189 (Reports in Connection with Permanent Closures of Department of Energy Defense Nuclear Facilities), which requires submittal of a Closure Report to Congress by the Secretary of Energy upon the permanent cessation of production operations at a US Department of Energy (DOE) defense nuclear facility (Watkins 1991). This closure report provides: (1) A complete survey of the environmental problems at the facility; (2) Budget quality data indicating the cost of environmental restoration and other remediation and cleanup efforts at the facility; (3) A proposed cleanup schedule.

  14. Directly acting spring loaded safety valves as shock reducing measure

    International Nuclear Information System (INIS)

    Ismaier, A.; Schluecker, E.

    2010-01-01

    Hydraulic shocks as induced by fast closure of armatures or by sudden pump failures are massive impacts in piping systems and require extensive measures to absorb the generated load. Basically the avoidance of water hammers are preferable but in case of emergency shutdowns unavoidable hydraulic shocks have to be reduced by appropriate measures. The authors describe experiments with spring loaded safety valves as shock reducing measures. It was shown that the vale dimensions is essential for the efficacy. A realistic modeling is possible using the one-dimensional fluid mechanics code ROLAST.

  15. Interferometric Imaging Directly with Closure Phases and Closure Amplitudes

    Science.gov (United States)

    Chael, Andrew A.; Johnson, Michael D.; Bouman, Katherine L.; Blackburn, Lindy L.; Akiyama, Kazunori; Narayan, Ramesh

    2018-04-01

    Interferometric imaging now achieves angular resolutions as fine as ∼10 μas, probing scales that are inaccessible to single telescopes. Traditional synthesis imaging methods require calibrated visibilities; however, interferometric calibration is challenging, especially at high frequencies. Nevertheless, most studies present only a single image of their data after a process of “self-calibration,” an iterative procedure where the initial image and calibration assumptions can significantly influence the final image. We present a method for efficient interferometric imaging directly using only closure amplitudes and closure phases, which are immune to station-based calibration errors. Closure-only imaging provides results that are as noncommittal as possible and allows for reconstructing an image independently from separate amplitude and phase self-calibration. While closure-only imaging eliminates some image information (e.g., the total image flux density and the image centroid), this information can be recovered through a small number of additional constraints. We demonstrate that closure-only imaging can produce high-fidelity results, even for sparse arrays such as the Event Horizon Telescope, and that the resulting images are independent of the level of systematic amplitude error. We apply closure imaging to VLBA and ALMA data and show that it is capable of matching or exceeding the performance of traditional self-calibration and CLEAN for these data sets.

  16. Cyclonic valve test: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Monteiro, Andre Sampaio; Moraes, Carlos Alberto C.; Marins, Luiz Philipe M.; Soares, Fabricio; Oliveira, Dennis; Lima, Fabio Soares de; Airao, Vinicius [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil); Ton, Tijmen [Twister BV, Rijswijk (Netherlands)

    2012-07-01

    For many years, the petroleum industry has been developing a valve that input less shear to the flow for a given required pressure drop and this can be done using the cyclonic concept. This paper presents a comparison between the performances of a cyclonic valve (low shear) and a conventional globe valve. The aim of this work is to show the advantages of using a cyclonic low shear valve instead of the commonly used in the primary separation process by PETROBRAS. Tests were performed at PETROBRAS Experimental Center (NUEX) in Aracaju/SE varying some parameters: water cut; pressure loss (from 4 kgf/cm2 to 10 kgf/cm2); flow rates (30 m3/h and 45 m3/h). Results indicates a better performance of the cyclonic valve, if compared with a conventional one, and also that the difference of the performance, is a function of several parameters (emulsion stability, water content free, and oil properties). The cyclonic valve tested can be applied as a choke valve, as a valve between separation stages (for pressure drop), or for controlling the level of vessels. We must emphasize the importance to avoid the high shear imposed by conventional valves, because once the emulsion is created, it becomes more difficult to break it. New tests are being planned to occur in 2012, but PETROBRAS is also analyzing real cases where the applications could increase the primary process efficiency. In the same way, the future installations are also being designed considering the cyclonic valve usage. (author)

  17. Transient analysis for a system with a tilted disc check valve

    International Nuclear Information System (INIS)

    Jeung, Jaesik; Lee, Kyukwang; Cho, Daegwan

    2014-01-01

    Check valves are used to prevent reverse flow conditions in a variety of systems in nuclear power plants. When a check valve is closed by a reverse flow, the transient load can jeopardize the structural integrity on the piping system and its supports. It may also damage intended function of the in-line components even though the severity of the load differs and depends strongly on types of the check valves. To incorporate the transient load in the piping system, it is very important to properly predict the system response to transients such as a check valve closure accompanied by pump trip and to evaluate the system transient. The one-dimensional transient simulation codes such as the RELAP5/MOD3.3 and TRACE were used. There has not been a single model that integrates the two codes to handle the behavior of a tilted disc check valve, which is designed to mitigate check valve slams by shorting the travel of the disc. In this paper a model is presented to predict the dynamic motion of a tilted disc check valve in the transient simulation using the RELAP5/MOD3.3 code and the model is incorporated in a system transient analysis using control variables of the code. In addition, transient analysis for Essential Service Water (ESW) system is performed using the proposed model and the associated load is evaluated for the system. (author)

  18. Borehole closure in salt

    International Nuclear Information System (INIS)

    Fuenkajorn, K.; Daemen, J.J.K.

    1988-12-01

    Constitutive law parameters are determined from salt behavior characterization experiments. The results are applied to predict creep (time-dependent) closure of boreholes in salt specimens subjected to various loading configurations. Rheological models (linear and nonlinear viscoelastic and viscoplastic models), empirical models, and physical theory models have been formulated from the results of uniaxial creep tests, strain and stress rate controlled uniaxial tests, constant strain rate triaxial tests, cyclic loading tests, and seismic velocity measurements. Analytical solutions for a thick-walled cylinder subjected to internal and external pressures and for a circular hole in an infinite plate subjected to a biaxial or uniaxial stressfield have been derived from each of the linear viscoelastic models and from one of the empirical laws. The experimental results indicate that the salt samples behave as an elastic-viscoplastic material. The elastic behavior tends to be linear and time-independent. The plastic deformation is time-dependent. The stress increment to strain rate increment ratio gradually decreases as the stress level increases. The transient potential creep law seems to give the simplest satisfactory governing equation describing the viscoplastic behavior of salt during the transient phase. 204 refs., 27 figs., 29 tabs

  19. Posterior Urethral Valves

    Directory of Open Access Journals (Sweden)

    Steve J. Hodges

    2009-01-01

    Full Text Available The most common cause of lower urinary tract obstruction in male infants is posterior urethral valves. Although the incidence has remained stable, the neonatal mortality for this disorder has improved due to early diagnosis and intensive neonatal care, thanks in part to the widespread use of prenatal ultrasound evaluations. In fact, the most common reason for the diagnosis of posterior urethral valves presently is the evaluation of infants for prenatal hydronephrosis. Since these children are often diagnosed early, the urethral obstruction can be alleviated rapidly through catheter insertion and eventual surgery, and their metabolic derangements can be normalized without delay, avoiding preventable infant mortality. Of the children that survive, however, early diagnosis has not had much effect on their long-term prognosis, as 30% still develop renal insufficiency before adolescence. A better understanding of the exact cause of the congenital obstruction of the male posterior urethra, prevention of postnatal bladder and renal injury, and the development of safe methods to treat urethral obstruction prenatally (and thereby avoiding the bladder and renal damage due to obstructive uropathy are the goals for the care of children with posterior urethral valves[1].

  20. Anterior Urethral Valves

    Directory of Open Access Journals (Sweden)

    Vidyadhar P. Mali

    2006-07-01

    Full Text Available We studied the clinical presentation and management of four patients with anterior urethral valves; a rare cause of urethral obstruction in male children. One patient presented antenatally with oligohydramnios, bilateral hydronephrosis and bladder thickening suggestive of an infravesical obstruction. Two other patients presented postnatally at 1 and 2 years of age, respectively, with poor stream of urine since birth. The fourth patient presented at 9 years with frequency and dysuria. Diagnosis was established on either micturating cystourethrogram (MCU (in 2 or on cystoscopy (in 2. All patients had cystoscopic ablation of the valves. One patient developed a postablation stricture that was resected with an end-to-end urethroplasty. He had an associated bilateral vesicoureteric junction (VUJ obstruction for which a bilateral ureteric reimplantation was done at the same time. On long-term follow-up, all patients demonstrated a good stream of urine. The renal function is normal. Patients are continent and free of urinary infections. Anterior urethral valves are rare obstructive lesions in male children. The degree of obstruction is variable, and so they may present with mild micturition difficulty or severe obstruction with hydroureteronephrosis and renal impairment. Hence, it is important to evaluate the anterior urethra in any male child with suspected infravesical obstruction. The diagnosis is established by MCU or cystoscopy and the treatment is always surgical, either a transurethral ablation or an open resection. The long-term prognosis is good.

  1. Closure and Sealing Design Calculation

    International Nuclear Information System (INIS)

    T. Lahnalampi; J. Case

    2005-01-01

    The purpose of the ''Closure and Sealing Design Calculation'' is to illustrate closure and sealing methods for sealing shafts, ramps, and identify boreholes that require sealing in order to limit the potential of water infiltration. In addition, this calculation will provide a description of the magma that can reduce the consequences of an igneous event intersecting the repository. This calculation will also include a listing of the project requirements related to closure and sealing. The scope of this calculation is to: summarize applicable project requirements and codes relating to backfilling nonemplacement openings, removal of uncommitted materials from the subsurface, installation of drip shields, and erecting monuments; compile an inventory of boreholes that are found in the area of the subsurface repository; describe the magma bulkhead feature and location; and include figures for the proposed shaft and ramp seals. The objective of this calculation is to: categorize the boreholes for sealing by depth and proximity to the subsurface repository; develop drawing figures which show the location and geometry for the magma bulkhead; include the shaft seal figures and a proposed construction sequence; and include the ramp seal figure and a proposed construction sequence. The intent of this closure and sealing calculation is to support the License Application by providing a description of the closure and sealing methods for the Safety Analysis Report. The closure and sealing calculation will also provide input for Post Closure Activities by describing the location of the magma bulkhead. This calculation is limited to describing the final configuration of the sealing and backfill systems for the underground area. The methods and procedures used to place the backfill and remove uncommitted materials (such as concrete) from the repository and detailed design of the magma bulkhead will be the subject of separate analyses or calculations. Post-closure monitoring will not

  2. Surgical removal of atrial septal defect occlusion device and mitral valve replacement in a 39-year-old female patient with infective endocarditis

    Directory of Open Access Journals (Sweden)

    A S Zotov

    2018-02-01

    Full Text Available Atrial septal defects represent the second most frequent congenital heart disease after ventricular septal defects. Transcatheter closure of an atrial septal defect is usually performed following strict indications on patients with significant left-to-right shunt. Infective endocarditis after transcatheter implantation of atrial septal defect occluder is an extremely rare complication. We report a case of infective endocarditis of the mitral valve (with severe mitral valve insufficiency in a 39-year-old female patient 13 years after transcatheter closure of an atrial septal defect. Complex prophylactic antibiotic coverage was performed prior to surgical intervention. Surgical removal of atrial septal defect occluder, mitral valve replacement, atrial septal defect closure and left atrial appendage resection were performed. Postoperative course was uneventful.

  3. Fracturing mechanics before valve-in-valve therapy of small aortic bioprosthetic heart valves.

    Science.gov (United States)

    Johansen, Peter; Engholt, Henrik; Tang, Mariann; Nybo, Rasmus F; Rasmussen, Per D; Nielsen-Kudsk, Jens Erik

    2017-10-13

    Patients with degraded bioprosthetic heart valves (BHV) who are not candidates for valve replacement may benefit from transcatheter valve-in-valve (VIV) therapy. However, in smaller-sized surgical BHV the resultant orifice may become too narrow. To overcome this, the valve frame can be fractured by a high-pressure balloon prior to VIV. However, knowledge on fracture pressures and mechanics are prerequisites. The aim of this study was to identify the fracture pressures needed in BHV, and to describe the fracture mechanics. Commonly used BHV of small sizes were mounted on a high-pressure balloon situated in a biplane fluoroscopic system with a high-speed camera. The instant of fracture was captured along with the balloon pressure. The valves were inspected for material protrusion and later dissected for fracture zone investigation and description. The valves with a polymer frame fractured at a lower pressure (8-10 atm) than those with a metal stent (19-26 atm). None of the fractured valves had elements protruding. VIV procedures in small-sized BHV may be performed after prior fracture of the valve frame by high-pressure balloon dilatation. This study provides tentative guidelines for expected balloon sizes and pressures for valve fracturing.

  4. Automatic fire hydrant valve development

    International Nuclear Information System (INIS)

    Drumheller, K.

    1976-01-01

    The development of a remotely-controlled valve to operate a fire hydrant is described. Assembled from off-the-shelf components, the prototype illustrates that a valve light enough to be handled by one man is possible. However, it does not have the ruggedness or reliability needed for actual fire-fighting operations. Preliminary testing by City of Tacoma fire department personnel indicates that the valve may indeed contribute significantly to fire-fighting efficiency

  5. [Ahmed valve in glaucoma surgery].

    Science.gov (United States)

    Bikbov, M M; Khusnitdinov, I I

    This is a review on Ahmed valve application in glaucoma surgery. It contains, in particular, data on the Ahmed valve efficiency, results of experimental and histological studies of filtering bleb encapsulation, examines the use of antimetabolites and anti-VEGF agents, and discusses implantation techniques. The current appraisal of antimetabolites delivery systems integrated into the Ahmed valve is presented. Various complications encountered in practice and preventive measures are also covered.

  6. Thermal fatigue behavior of valves

    International Nuclear Information System (INIS)

    Moinereau, D.; Scliffet, L.; Capion, J.C.; Genette, P.

    1991-01-01

    This paper reports that valves of pressurized water reactors are exposed to thermal shocks during transient operations. The numerous thermal shock tests performed on valves on the EDF test facilities have shown the sensibility of fillets and geometrical discontinuities to thermal fatigue: cracks can appear in those areas and grow through the valve body. Valves systems designated as level 1 must be designed to withstand fatigue up to the second isolation valve: the relevant rule is specified in the paragraph B 3500 of the French RCCM code. It is a simplified method which doesn't require finite element calculations. Many valve systems have been designed according to this rule and have been operated without accident. However, in one case, important cracks were found in the fillet of a check-valve after numerous thermal shocks. Calculation of the valve's behavior according to the RCCM code to estimate the fatigue damage resulting from thermal shocks led to a low damage factor, which doesn't agree with the experimental results. This was confirmed by new testings and showed the inadequacy of B 3500 rule for thermal transients. On this base a new rule is proposed to estimate fatigue damage resulting from thermal shocks. An experimental program has been realized to validate this rule. Axisymetrical analytical mock-ups with different geometries and one check-valve in austenitic stainless steel 316 L have been submitted to hot thermal shocks of 210 degrees C magnitude

  7. Latest design of gate valves

    Energy Technology Data Exchange (ETDEWEB)

    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. Fluid mechanics of heart valves.

    Science.gov (United States)

    Yoganathan, Ajit P; He, Zhaoming; Casey Jones, S

    2004-01-01

    Valvular heart disease is a life-threatening disease that afflicts millions of people worldwide and leads to approximately 250,000 valve repairs and/or replacements each year. Malfunction of a native valve impairs its efficient fluid mechanic/hemodynamic performance. Artificial heart valves have been used since 1960 to replace diseased native valves and have saved millions of lives. Unfortunately, despite four decades of use, these devices are less than ideal and lead to many complications. Many of these complications/problems are directly related to the fluid mechanics associated with the various mechanical and bioprosthetic valve designs. This review focuses on the state-of-the-art experimental and computational fluid mechanics of native and prosthetic heart valves in current clinical use. The fluid dynamic performance characteristics of caged-ball, tilting-disc, bileaflet mechanical valves and porcine and pericardial stented and nonstented bioprostheic valves are reviewed. Other issues related to heart valve performance, such as biomaterials, solid mechanics, tissue mechanics, and durability, are not addressed in this review.

  9. Surge-damping vacuum valve

    International Nuclear Information System (INIS)

    Bullock, J.C.; Kelley, B.E.

    1977-01-01

    A valve for damping out flow surges in a vacuum system is described. The surge-damping mechanism consists of a slotted, spring-loaded disk adjacent to the valve's vacuum port (the flow passage to the vacuum roughing pump). Under flow surge conditions, the differential pressure forces the disk into a sealing engagement with the vacuum port, thereby restricting the gas flow path to narrow slots in the disk's periphery. The increased flow damps out the flow surge. When pressure is equalized on both sides of the valve, the spring load moves the disk away from the port to restore full flow conductance through the valve

  10. Analytical study on water hammer pressure in pressurized conduits with a throttled surge chamber for slow closure

    Directory of Open Access Journals (Sweden)

    Yong-liang Zhang

    2010-06-01

    Full Text Available This paper presents an analytical investigation of water hammer in a hydraulic pressurized pipe system with a throttled surge chamber located at the junction between a tunnel and a penstock, and a valve positioned at the downstream end of the penstock. Analytical formulas of maximum water hammer pressures at the downstream end of the tunnel and the valve were derived for a system subjected to linear and slow valve closure. The analytical results were then compared with numerical ones obtained using the method of characteristics. There is agreement between them. The formulas can be applied to estimating water hammer pressure at the valve and transmission of water hammer pressure through the surge chamber at the junction for a hydraulic pipe system with a surge chamber.

  11. Heart Valve Surgery Recovery and Follow Up

    Science.gov (United States)

    ... Guide: Understanding Your Heart Valve Problem | Spanish Symptom Tracker | Spanish Pre-surgery Checklist | Spanish What Is Heart ... Heart Valves • Heart Valve Problems and Causes • Risks, Signs and Symptoms • Accurate Diagnosis • Treatment Options • Recovery and ...

  12. 241-AN-A valve pit manifold valves and position indication acceptance test procedure

    Energy Technology Data Exchange (ETDEWEB)

    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.

  13. Aortic valve replacement

    DEFF Research Database (Denmark)

    Kapetanakis, Emmanouil I; Athanasiou, Thanos; Mestres, Carlos A

    2008-01-01

    mortality were collected. Group analysis by patient geographic distribution and by annular diameter of the prosthesis utilized was conducted. Patients with a manufacturer's labeled prosthesis size > or = 21 mm were assigned to the 'large' aortic size subset, while those with a prosthesis size ... differences in the distribution of either gender or BSA. In the multivariable model, south European patients were seven times more likely to receive a smaller-sized aortic valve (OR = 6.5, 95% CI = 4.82-8.83, p

  14. Method of effecting fast turbine valving for improvement of power system stability

    International Nuclear Information System (INIS)

    Park, R.H.

    1981-01-01

    As a improved way of effecting fast valving of turbines of power system steam-electric generating units for the purpose of improving the stability of power transmission over transmission circuits to which their generators make connection, when stability is threatened by line faults and certain other stability endangering events, the heretofore employed and/or advocated practice of automatically closing intercept valves at fastest available closing speed in response to a fast valving signal, and thereafter automatically fully reopening them in a matter of seconds, is modified by providing to reopen the valves only partially to and thereafter retain them at a preset partially open position. For best results the process of what can be termed sustained partial reopening is so effected as to result in its completion within a fraction of a second following the peak of the first forward swing of the generator rotor. Control valves may be either held open, or automatically fully or partly closed and thereafter fully opened in a preprogrammed manner, or automatically moved to and thereafter held in a partly closed position, by means of a preprogrammed process of repositioning in which the valves may optionally be first fully or partly closed and thereafter partly reopened. Avoidance of discharge of steam through high pressure safety valves can be had with use of suitably controlled power operated valves that discharge steam to the condenser or to atmosphere. Where there is an intermediate pressure turbine that is supplied with superheated steam, use of sustained partial control valve closure, if employed, is supplemented by provision for reduction of rate of heat release within the steam generator in order to protect the reheater from overheating. As a way to restrict increase of reheat pressure of fossil fuel installations, and to minimize increase in the msr (Moisture separator-reheater) pressure of nuclear units, provision is optionally made of normally closed by-pass v

  15. BNGS B valve packing program

    International Nuclear Information System (INIS)

    Cumming, D.

    1995-01-01

    The Bruce B Valve Packing Program began in 1987. The early history and development were presented at the 1992 International CANDU Maintenance conference. This presentation covers the evolution of the Bruce B Valve Packing Program over the period 1992 to 1995. (author)

  16. Surgical treatment of tetralogy of Fallot with absent pulmonary valve syndrome.

    Science.gov (United States)

    Tanaka, Yuki; Miyamoto, Takashi; Naito, Yuji; Yoshitake, Shuichi

    2016-06-01

    The patient was a 3-month-old girl weighting 3.6 kg, diagnosed with tetralogy of Fallot and absent pulmonary valve syndrome. We surgically repaired the tetralogy of Fallot by patch closure of the ventricular septal defect, right ventricular outflow tract reconstruction using an expanded polytetrafluoroethylene monocusp patch with a bulging sinus, and removal of the bronchial obstruction by anterior translocation of the pulmonary artery using the Lecompte maneuver. © The Author(s) 2015.

  17. Fuel channel closure and adapter

    International Nuclear Information System (INIS)

    Cashen, W.S.

    1985-01-01

    This invention provides a mechanical closure/actuating ram combination particularly suited for use in sealing the ends of the pressure tubes when a CANDU-type reactor is refueled. It provides a cluster that may be inserted into a fuel channel end fitting to provide at least partial closing off of a pressure tube while permitting the disengagement of the fueling machine and its withdrawal from the closure for other purposes. The invention also provides a ram/closure combination wherein the application of loading force to a deformable sealing disk is regulated by a massive load bar component forming part of the fueling machine and being therefore accessible for maintenance or replacement

  18. Experience with valves for PHWR reactors

    International Nuclear Information System (INIS)

    Narayan, K.; Mhetre, S.G.

    1977-01-01

    Material specifications and inspection and testing requirements of the valves meant for use in nuclear reactors are mentioned. In the heavy water systems (both primary and moderator) of a PHWR type reactor, the valves used are gate valves, globe valves, diaphragm valves, butterfly valves, check valves and relief valves. Their locations and functions they perform in the Rajasthan Atomic Power Station Unit-1 are described. Experience with them is given. The major problems encountered with them have been : (1) leakage from the stem seals and body bonnet joint, (2) leakage due to failure of diaphragm and/or washout of the packing and (3) malfunctioning. Measures taken to solve these are discussed. Finally a mention has been made of improved versions of valves, namely, metal diaphragm valve and inverted relief valve. (M.G.B.)

  19. Stem thrust prediction model for W-K-M double wedge parallel expanding gate valves

    Energy Technology Data Exchange (ETDEWEB)

    Eldiwany, B.; Alvarez, P.D. [Kalsi Engineering Inc., Sugar Land, TX (United States); Wolfe, K. [Electric Power Research Institute, Palo Alto, CA (United States)

    1996-12-01

    An analytical model for determining the required valve stem thrust during opening and closing strokes of W-K-M parallel expanding gate valves was developed as part of the EPRI Motor-Operated Valve Performance Prediction Methodology (EPRI MOV PPM) Program. The model was validated against measured stem thrust data obtained from in-situ testing of three W-K-M valves. Model predictions show favorable, bounding agreement with the measured data for valves with Stellite 6 hardfacing on the disks and seat rings for water flow in the preferred flow direction (gate downstream). The maximum required thrust to open and to close the valve (excluding wedging and unwedging forces) occurs at a slightly open position and not at the fully closed position. In the nonpreferred flow direction, the model shows that premature wedging can occur during {Delta}P closure strokes even when the coefficients of friction at different sliding surfaces are within the typical range. This paper summarizes the model description and comparison against test data.

  20. Cavitation behavior observed in three monoleaflet mechanical heart valves under accelerated testing conditions.

    Science.gov (United States)

    Lo, Chi-Wen; Liu, Jia-Shing; Li, Chi-Pei; Lu, Po-Chien; Hwang, Ned H

    2008-01-01

    Accelerated testing provides a substantial amount of data on mechanical heart valve durability in a short period of time, but such conditions may not accurately reflect in vivo performance. Cavitation, which occurs during mechanical heart valve closure when local flow field pressure decreases below vapor pressure, is thought to play a role in valve damage under accelerated conditions. The underlying flow dynamics and mechanisms behind cavitation bubble formation are poorly understood. Under physiologic conditions, random perivalvular cavitation is difficult to capture. We applied accelerated testing at a pulse rate of 600 bpm and transvalvular pressure of 120 mm Hg, with synchronized videographs and high-frequency pressure measurements, to study cavitation of the Medtronic Hall Standard (MHS), Medtronic Hall D-16 (MHD), and Omni Carbon (OC) valves. Results showed cavitation bubbles between 340 and 360 micros after leaflet/housing impact of the MHS, MHD, and OC valves, intensified by significant leaflet rebound. Squeeze flow, Venturi, and water hammer effects each contributed to cavitation, depending on valve design.

  1. Stem thrust prediction model for W-K-M double wedge parallel expanding gate valves

    International Nuclear Information System (INIS)

    Eldiwany, B.; Alvarez, P.D.; Wolfe, K.

    1996-01-01

    An analytical model for determining the required valve stem thrust during opening and closing strokes of W-K-M parallel expanding gate valves was developed as part of the EPRI Motor-Operated Valve Performance Prediction Methodology (EPRI MOV PPM) Program. The model was validated against measured stem thrust data obtained from in-situ testing of three W-K-M valves. Model predictions show favorable, bounding agreement with the measured data for valves with Stellite 6 hardfacing on the disks and seat rings for water flow in the preferred flow direction (gate downstream). The maximum required thrust to open and to close the valve (excluding wedging and unwedging forces) occurs at a slightly open position and not at the fully closed position. In the nonpreferred flow direction, the model shows that premature wedging can occur during ΔP closure strokes even when the coefficients of friction at different sliding surfaces are within the typical range. This paper summarizes the model description and comparison against test data

  2. 40 CFR 265.280 - Closure and post-closure.

    Science.gov (United States)

    2010-07-01

    ... contaminants caused by wind erosion; and (4) Compliance with § 265.276 concerning the growth of food-chain... and post-closure care objectives of paragraph (a) of this section: (1) Type and amount of hazardous..., including amount, frequency, and pH of precipitation; (5) Geological and soil profiles and surface and...

  3. Mathematical multi-scale model of the cardiovascular system including mitral valve dynamics. Application to ischemic mitral insufficiency

    Directory of Open Access Journals (Sweden)

    Moonen Marie

    2011-09-01

    Full Text Available Abstract Background Valve dysfunction is a common cardiovascular pathology. Despite significant clinical research, there is little formal study of how valve dysfunction affects overall circulatory dynamics. Validated models would offer the ability to better understand these dynamics and thus optimize diagnosis, as well as surgical and other interventions. Methods A cardiovascular and circulatory system (CVS model has already been validated in silico, and in several animal model studies. It accounts for valve dynamics using Heaviside functions to simulate a physiologically accurate "open on pressure, close on flow" law. However, it does not consider real-time valve opening dynamics and therefore does not fully capture valve dysfunction, particularly where the dysfunction involves partial closure. This research describes an updated version of this previous closed-loop CVS model that includes the progressive opening of the mitral valve, and is defined over the full cardiac cycle. Results Simulations of the cardiovascular system with healthy mitral valve are performed, and, the global hemodynamic behaviour is studied compared with previously validated results. The error between resulting pressure-volume (PV loops of already validated CVS model and the new CVS model that includes the progressive opening of the mitral valve is assessed and remains within typical measurement error and variability. Simulations of ischemic mitral insufficiency are also performed. Pressure-Volume loops, transmitral flow evolution and mitral valve aperture area evolution follow reported measurements in shape, amplitude and trends. Conclusions The resulting cardiovascular system model including mitral valve dynamics provides a foundation for clinical validation and the study of valvular dysfunction in vivo. The overall models and results could readily be generalised to other cardiac valves.

  4. Prosthetic valve endocarditis after transcatheter aortic valve implantation

    DEFF Research Database (Denmark)

    Olsen, Niels Thue; De Backer, Ole; Thyregod, Hans G H

    2015-01-01

    BACKGROUND: Transcatheter aortic valve implantation (TAVI) is an advancing mode of treatment for inoperable or high-risk patients with aortic stenosis. Prosthetic valve endocarditis (PVE) after TAVI is a serious complication, but only limited data exist on its incidence, outcome, and procedural......%) were treated conservatively and 1 with surgery. Four patients (22%) died from endocarditis or complications to treatment, 2 of those (11%) during initial hospitalization for PVE. An increased risk of TAVI-PVE was seen in patients with low implanted valve position (hazard ratio, 2.8 [1.1-7.2]), moderate...

  5. Development of an ITER prototype disruption mitigation valve

    Energy Technology Data Exchange (ETDEWEB)

    Czymek, G., E-mail: g.czymek@fz-juelich.de [Institute of Energy and Climate Research – Plasma Physics, Forschungszentrum Jülich GmbH, D52425 Jülich (Germany); Giesen, B., E-mail: ingenieurbuero.giesen@gmx.de [IBG, Sibertstr. 22, D-52525 Heinsberg (Germany); Charl, A.; Panin, A.; Hiller, A.; Nicolai, D.; Neubauer, O.; Koslowski, H.R.; Sandri, N. [Institute of Energy and Climate Research – Plasma Physics, Forschungszentrum Jülich GmbH, D52425 Jülich (Germany)

    2015-10-15

    Highlights: • An ITER-DMV prototype for 100 bar, D = 80 mm, opening time 3.5 ms, is ready for fabrication. • The vacuum part is sealed against the working gas by stainless steel bellows for 110 bar. • The conical Laval gas outlet allows maximal mass flow rate. • The eddy current drive turn ratio was optimized for low tilting moment. • Polyimide is used for the head sealing, the decelerator and for the bearing of the guide tube. - Abstract: Disruptions in tokamaks seem to be unavoidable. Consequences of disruptions are (i) high heat loads on plasma-facing components, (ii) large forces on the vacuum vessel, and (iii) the generation of runaway electron beams. In ITER, the thermal energy of the plasma needs to be evenly distributed on the first wall in order to prevent melting, forces from vertical displacement events have to be minimized, and the generation of runaway electrons suppressed. Massive gas injection using fast valves is a concept for disruption mitigation which is presently being explored in many tokamaks. Fast disruption mitigation valves based on an electromagnetic eddy current drive have been developed in Jülich since the 1990s and models of various sizes have been built and are in operation in the TEXTOR, MAST, and JET tokamaks. A disruption mitigation valve for ITER is of necessity larger with an estimated injected gas volume of ∼20 kPa m{sup 3}[7] for runaway electron suppression and all materials used have to be resistant to much higher levels of neutron and gamma radiation than in existing tokamaks. During the last 5 years, the concept for an ITER prototype disruption mitigation valve has been developed up to the stage that a fully functional valve could be built and tested. Special emphasis was given to the development and functional testing of some critical items: (i) the injection chamber seal, (ii) the piston seal, (iii) the eddy current drive, and (iv) a braking mechanism to avoid too fast closure of the valve, which could damage

  6. Pannus-related prosthetic valve dysfunction. Case report.

    Science.gov (United States)

    Moldovan, Maria-Sînziana; Bedeleanu, Daniela; Kovacs, Emese; Ciumărnean, Lorena; Molnar, Adrian

    2016-01-01

    Pannus-related prosthetic valve dysfunction, a complication of mechanical prosthetic valve replacement, is rare, with a slowly progressive evolution, but it can be acute, severe, requiring surgical reintervention. We present the case of a patient with a mechanical single disc aortic prosthesis, with moderate prosthesis-patient mismatch, minor pannus found on previous ultrasound examinations, who presented to our service with angina pain with a duration of 1 hour, subsequently interpreted as non-ST segment elevation myocardial infarction (NSTEMI) syndrome. Coronarography showed normal epicardial coronary arteries, an ample movement of the prosthetic disc, without evidence of coronary thromboembolism, and Gated Single-Photon Emission Computerized Tomography (SPECT) with Technetium (Tc)-99m detected no perfusion defects. Transthoracic echocardiography (TTE) evidenced a dysfunctional prosthesis due to a subvalvular mass; transesophageal echocardiography (TOE) showed the interference of this mass, with a pannus appearance, with the closure of the prosthetic disc. Under conditions of repeated angina episodes, under anticoagulant treatment, surgery was performed, with the intraoperative confirmation of pannus and its removal. Postoperative evolution was favorable. This case reflects the diagnostic and therapeutic management problems of pannus-related prosthetic valve dysfunction.

  7. 50 CFR 648.161 - Closures.

    Science.gov (United States)

    2010-10-01

    ... Bluefish Fishery § 648.161 Closures. (a) EEZ closure. NMFS shall close the EEZ to fishing for bluefish by... dealer permit holders that no commercial quota is available for landing bluefish in that state. ...

  8. Moment Closure for the Stochastic Logistic Model

    National Research Council Canada - National Science Library

    Singh, Abhyudai; Hespanha, Joao P

    2006-01-01

    ..., which we refer to as the moment closure function. In this paper, a systematic procedure for constructing moment closure functions of arbitrary order is presented for the stochastic logistic model...

  9. Cavitation guide for control valves

    Energy Technology Data Exchange (ETDEWEB)

    Tullis, J.P. [Tullis Engineering Consultants, Logan, UT (United States)

    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.

  10. Cavitation guide for control valves

    International Nuclear Information System (INIS)

    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. Characteristic analysis of servo valve

    International Nuclear Information System (INIS)

    Ko, J. H.; Ryu, D. R.; Lee, J. H.; Kim, Y. S.; Na, J. C.; Kim, D. S.

    2008-01-01

    Electro-pneumatic servo valve is an electro-mechanical device which converts electric signals into a proper pneumatic flow rate or pressure. In order to improve the overall performance of pneumatic servo systems, electro-pneumatic servo valves are required, which have fast dynamic characteristics, no air leakage at a null point, and can be fabricated at a low-cost. The first objective of this research is to design and to fabricate a new electro-pneumatic servo valve which satisfies the above-mentioned requirements. In order to design the mechanism of the servo valve optimally, the flow inside the valve depending upon the position of spool was analyzed variously, and on the basis of such analysis results, the valve mechanism, which was formed by combination of the spool and the sleeve, was designed and manufactured. And a tester for conducting an overall performance test was designed and manufactured, and as a result of conducting the flow rate test, the pressure test and the frequency test on the developed pneumatic servo valve

  12. Analysis of a postulated pipe rupture and subsequent check valve slam of a PWR feedwater line

    International Nuclear Information System (INIS)

    Chang, K.C.; Adams, T.M.

    1983-01-01

    System designs criteria employed in the design of pressurized water reactors (PWR) requires that, for a postulated instantaneous guillotine rupture anywhere in the steam generator feedwater system, no more than one steam generator can be allowed to blowdown. Feedwater systems in many PWR's consist of pipe lines running from the feedwater pumps into a common feedwater header then branching into each steam generator from the header. The feedwater piping to each steam generator contains swing check valves to prevent reverse flow from the steam generator. This activation of some or all of these check valves significantly complicates the system structural analysis in that not only the blowdown forces resulting from the postulated pipe rupture, but also the water hammer loads resulting from closure of the check valve at high reverse flow velocities must be considered. The loads resulting from system blowdown and check valve closure are axial in nature. Peak loads ranging from 130000 lbs. to 180000 lbs. are not uncommon and are layout dependent. The analysis and design to withstand this transient loading deviates from the usual feedwater line design in that supports are required along the piping axis in the direction normal to the usual seismic supports. A brief and general discussion of the methods employed in the generation of the thermal-hydraulic loadings is presented. However, the discussion emphasizes the piping and piping support structural design and analysis method and approaches used in evaluating a selected portion of such a feedwater system. (orig./RW)

  13. Developments in mechanical heart valve prosthesis

    Indian Academy of Sciences (India)

    Artificial heart valves are engineered devices used for replacing diseased or damaged natural valves of the heart. Most commonly used for replacement are mechanical heart valves and biological valves. This paper briefly outlines the evolution, designs employed, materials being used,. and important factors that affect the ...

  14. CIRSE Vascular Closure Device Registry

    International Nuclear Information System (INIS)

    Reekers, Jim A.; Müller-Hülsbeck, Stefan; Libicher, Martin; Atar, Eli; Trentmann, Jens; Goffette, Pierre; Borggrefe, Jan; Zeleňák, Kamil; Hooijboer, Pieter; Belli, Anna-Maria

    2011-01-01

    Purpose: Vascular closure devices are routinely used after many vascular interventional radiology procedures. However, there have been no major multicenter studies to assess the safety and effectiveness of the routine use of closure devices in interventional radiology. Methods: The CIRSE registry of closure devices with an anchor and a plug started in January 2009 and ended in August 2009. A total of 1,107 patients were included in the registry. Results: Deployment success was 97.2%. Deployment failure specified to access type was 8.8% [95% confidence interval (95% CI) 5.0–14.5] for antegrade access and 1.8% (95% CI 1.1–2.9) for retrograde access (P = 0.001). There was no difference in deployment failure related to local PVD at the access site. Calcification was a reason for deployment failure in only 5.9 cm, and two vessel occlusions. Conclusion: The conclusion of this registry of closure devices with an anchor and a plug is that the use of this device in interventional radiology procedures is safe, with a low incidence of serious access site complications. There seems to be no difference in complications between antegrade and retrograde access and other parameters.

  15. 304 Concretion facility closure plan

    International Nuclear Information System (INIS)

    1990-04-01

    The Hanford Site, located northwest of Richland, Washington, houses reactors, chemical-separation systems, and related facilities used for the production of special nuclear materials. The 300 Area of the Hanford Site contains reactor fuel manufacturing facilities and several research and development laboratories. Recyclable scrap uranium Zircaloy-2 and copper silicon alloy, uranium-titanium alloy, beryllium/Zircaloy-2 alloy, and Zircaloy-2 chips and fines were secured in concrete billets in the 304 Concretion Facility, located in the 300 Area. The beryllium/Zircaloy-2 alloy and Zircaloy-2 chips and fines are designated as low-level radioactive mixed waste (LLRMW) with the characteristic of ignitability. The concretion process reduced the ignitability of the fines and chips for safe storage and shipment. This process has been discontinued and the 304 Concretion Facility is now undergoing closure as defined in the Resource Conservation and Recovery Act of 1976 (RCRA). This closure plan presents a description of the facility, the history of materials and wastes managed, and the procedures that will be followed to close the 304 Concretion Facility (304 Facility). Clean closure of the 304 Facility is the proposed method for closure of the facility. Justification for this proposal is presented. 15 refs., 22 figs., 4 tabs

  16. Telephone switchboard closure | 19 December

    CERN Multimedia

    2014-01-01

    Exceptionally, the telephone switchboard will close at 4 p.m. on Friday, 19 December, instead of the usual time of 6 p.m., to allow time for closing all systems properly before the annual closure. Therefore, switchboard operator assistance to transfer calls from/to external lines will stop. All other phone services will run as usual.

  17. CIRSE Vascular Closure Device Registry

    Science.gov (United States)

    Müller-Hülsbeck, Stefan; Libicher, Martin; Atar, Eli; Trentmann, Jens; Goffette, Pierre; Borggrefe, Jan; Zeleňák, Kamil; Hooijboer, Pieter; Belli, Anna-Maria

    2010-01-01

    Purpose Vascular closure devices are routinely used after many vascular interventional radiology procedures. However, there have been no major multicenter studies to assess the safety and effectiveness of the routine use of closure devices in interventional radiology. Methods The CIRSE registry of closure devices with an anchor and a plug started in January 2009 and ended in August 2009. A total of 1,107 patients were included in the registry. Results Deployment success was 97.2%. Deployment failure specified to access type was 8.8% [95% confidence interval (95% CI) 5.0–14.5] for antegrade access and 1.8% (95% CI 1.1–2.9) for retrograde access (P = 0.001). There was no difference in deployment failure related to local PVD at the access site. Calcification was a reason for deployment failure in only 5.9 cm, and two vessel occlusions. Conclusion The conclusion of this registry of closure devices with an anchor and a plug is that the use of this device in interventional radiology procedures is safe, with a low incidence of serious access site complications. There seems to be no difference in complications between antegrade and retrograde access and other parameters. PMID:20981425

  18. Butterfly valve torque prediction methodology

    International Nuclear Information System (INIS)

    Eldiwany, B.H.; Sharma, V.; Kalsi, M.S.; Wolfe, K.

    1994-01-01

    As part of the Motor-Operated Valve (MOV) Performance Prediction Program, the Electric Power Research Institute has sponsored the development of methodologies for predicting thrust and torque requirements of gate, globe, and butterfly MOVs. This paper presents the methodology that will be used by utilities to calculate the dynamic torque requirements for butterfly valves. The total dynamic torque at any disc position is the sum of the hydrodynamic torque, bearing torque (which is induced by the hydrodynamic force), as well as other small torque components (such as packing torque). The hydrodynamic torque on the valve disc, caused by the fluid flow through the valve, depends on the disc angle, flow velocity, upstream flow disturbances, disc shape, and the disc aspect ratio. The butterfly valve model provides sets of nondimensional flow and torque coefficients that can be used to predict flow rate and hydrodynamic torque throughout the disc stroke and to calculate the required actuation torque and the maximum transmitted torque throughout the opening and closing stroke. The scope of the model includes symmetric and nonsymmetric discs of different shapes and aspects ratios in compressible and incompressible fluid applications under both choked and nonchoked flow conditions. The model features were validated against test data from a comprehensive flowloop and in situ test program. These tests were designed to systematically address the effect of the following parameters on the required torque: valve size, disc shapes and disc aspect ratios, upstream elbow orientation and its proximity, and flow conditions. The applicability of the nondimensional coefficients to valves of different sizes was validated by performing tests on 42-in. valve and a precisely scaled 6-in. model. The butterfly valve model torque predictions were found to bound test data from the flow-loop and in situ testing, as shown in the examples provided in this paper

  19. Thermostatic Radiator Valve Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Dentz, J. [Advanced Residential Integrated Energy Solutions Collaborative (ARIES), New York, NY (United States); Ansanelli, E. [Advanced Residential Integrated Energy Solutions Collaborative (ARIES), New York, NY (United States)

    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).

  20. Transcatheter Mitral Valve-in-Ring Implantation

    LENUS (Irish Health Repository)

    Tanner, RE

    2018-05-01

    Failed surgical mitral valve repair using an annuloplasty ring has traditionally been treated with surgical valve replacement or repair1. For patients at high risk for repeat open heart surgery, placement of a trans-catheter aortic valve (i.e., TAVI valve) within the mitral ring (i.e., Mitral-Valve-in-Ring, MViR) has emerged as a novel alternative treatment strategy2-5 . We describe our experience of a failed mitral valve repair that was successfully treated with a TAVI valve delivered via the trans-septal approach, and summarise the data relating to this emerging treatment strategy.

  1. Valve leakage inspection testing and maintenance process

    International Nuclear Information System (INIS)

    Aikin, J.A.; Reinwald, J.W.; Kittmer, C.A.

    1991-01-01

    In valve maintenance, packing rings that prevent leakage along the valve stem must periodically be replaced, either during routine maintenance or to correct a leak or valve malfunction. Tools and procedures currently in use for valve packing removal and inspection are generally of limited value due to various access and application problems. A process has been developed by AECL Research that addresses these problems. The process, using incompressible fluid pressure, quickly and efficiently confirms the integrity of the valve backseat, extracts hard-to-remove valve packing sets, and verifies the leak tightness of the repacked valve

  2. Transcatheter, valve-in-valve transapical aortic and mitral valve implantation, in a high risk patient with aortic and mitral prosthetic valve stenoses

    Directory of Open Access Journals (Sweden)

    Harish Ramakrishna

    2015-01-01

    Full Text Available Transcatheter valve implantation continues to grow worldwide and has been used principally for the nonsurgical management of native aortic valvular disease-as a potentially less invasive method of valve replacement in high-risk and inoperable patients with severe aortic valve stenosis. Given the burden of valvular heart disease in the general population and the increasing numbers of patients who have had previous valve operations, we are now seeing a growing number of high-risk patients presenting with prosthetic valve stenosis, who are not potential surgical candidates. For this high-risk subset transcatheter valve delivery may be the only option. Here, we present an inoperable patient with severe, prosthetic valve aortic and mitral stenosis who was successfully treated with a trans catheter based approach, with a valve-in-valve implantation procedure of both aortic and mitral valves.

  3. 75 FR 29322 - Base Closure and Realignment

    Science.gov (United States)

    2010-05-25

    ... DEPARTMENT OF DEFENSE Office of the Secretary Base Closure and Realignment AGENCY: Office of...)(ii) of the Defense Base Closure and Realignment Act of 1990. It provides a partial list of military installations closing or realigning pursuant to the 2005 Base Closure and Realignment (BRAC) Report. It also...

  4. Project Management Approach to Transition of the Miamisburg Closure Project From Environmental Cleanup to Post-Closure Operations

    International Nuclear Information System (INIS)

    Carpenter, C.P.; Marks, M.L.; Smiley, S.L.; Gallaher, D.M.; Williams, K.D.

    2006-01-01

    The U.S. Department of Energy (DOE) used a project management approach to transition the Miamisburg Closure Project from cleanup by the Office of Environmental Management (EM) to post-closure operations by the Office of Legacy Management (LM). Two primary DOE orders were used to guide the site transition: DOE Order 430.1B, Real Property Asset Management, for assessment and disposition of real property assets and DOE Order 413.3, Program and Project Management for Acquisition of Capital Assets, for project closeout of environmental cleanup activities and project transition of post-closure activities. To effectively manage these multiple policy requirements, DOE chose to manage the Miamisburg Closure Project as a project under a cross-member transitional team using representatives from four principal organizations: DOE-LM, the LM contractor S.M. Stoller Corporation, DOE-EM, and the EM contractor CH2M Hill Mound Inc. The mission of LM is to manage the Department's post-transition responsibilities and long-term care of legacy liabilities and to ensure the future protection of human health and the environment for cleanup sites after the EM has completed its cleanup activities. (authors)

  5. Echocardiographic Follow-Up of Patent Foramen Ovale and the Factors Affecting Spontaneous Closure.

    Science.gov (United States)

    Yildirim, Ali; Aydin, Alperen; Demir, Tevfik; Aydin, Fatma; Ucar, Birsen; Kilic, Zubeyir

    2016-11-01

    The aim of the present study was to evaluate the echocardiographic follow-up of patent foramen ovale, which is considered a potential etiological factor in various diseases, and to determine the factors affecting spontaneous closure. Between January 2000 and June 2012, records of 918 patients with patent foramen ovale were retrospectively reviewed. Patency of less than 3 mm around the fossa ovalis is called patent foramen ovale. Patients with cyanotic congenital heart diseases, severe heart valve disorders and severe hemodynamic left to right shunts were excluded from the study. The patients were divided into three groups based on age; 1 day-1 month in group 1, 1 month-12 months in group 2, and more than 12 months in group 3. Of the 918 patients, 564 (61.4%) had spontaneous closure, 328 (35.8%) had patent foramen ovale continued, 15 (1.6%) patients had patent foramen ovale enlarged to 3-5 mm, 6 patients were enlarged to 5-8 mm, and in one patient patent foramen ovale reached to more than 8 mm size. Defect was spontaneously closed in 65.9% of the patients in group 1, 66.7% of the patients in group 2, and 52.3% of the patients in group 3. There was a negative correlation between the age of diagnosis and spontaneous closure (p patent ductus arteriosus and atrial septal aneurysm did not have any effect on spontaneous closure of patent foramen ovale (p > 0.05). However, ventricular septal defect and spontaneous closure of patent foramen ovale had a positive correlation (p closure rate of patent foramen ovale is high. Furthermore, a positive correlation was found between spontaneous closure of patent foramen ovale with early diagnosis and small defect size.

  6. Options for Heart Valve Replacement

    Science.gov (United States)

    ... Guide: Understanding Your Heart Valve Problem | Spanish Symptom Tracker | Spanish Pre-surgery Checklist | Spanish What Is Heart ... Cardiac Arrest: How Are They Different? 7 Warning Signs of a Heart Attack 8 Low Blood Pressure - ...

  7. Minimally invasive aortic valve replacement

    DEFF Research Database (Denmark)

    Foghsgaard, Signe; Schmidt, Thomas Andersen; Kjaergard, Henrik K

    2009-01-01

    In this descriptive prospective study, we evaluate the outcomes of surgery in 98 patients who were scheduled to undergo minimally invasive aortic valve replacement. These patients were compared with a group of 50 patients who underwent scheduled aortic valve replacement through a full sternotomy...... operations were completed as mini-sternotomies, 4 died later of noncardiac causes. The aortic cross-clamp and perfusion times were significantly different across all groups (P replacement...... is an excellent operation in selected patients, but its true advantages over conventional aortic valve replacement (other than a smaller scar) await evaluation by means of randomized clinical trial. The "extended mini-aortic valve replacement" operation, on the other hand, is a risky procedure that should...

  8. Regioselective intramolecular ring closure of 2-amino-6-bromo-2,6-dideoxyhexono-1,4-lactones to 5- or 6-membered iminuronic acid analogues:synthesis of 1-deoxymannojirimycin and 2,5-dideoxy-2,5-imino-D-glucitol

    DEFF Research Database (Denmark)

    Malle, Birgitte Mølholm; Lundt, Inge; Wrodnigg, Tanja M.

    2008-01-01

    closure took place by 5-exo attack on the 5,6-epoxide leading to 2,5-dideoxy-2,5-imino-L-gulonic acid (9b), which was reduced to 2,5-dideoxy-2,5-imino-D-glucitol (9c). The method was further applied to 2-amino-6-bromo-2,6-dideoxy-D-galacto- as well as D-talo-1,4-lactones (14 and 15). However, only......-galacto- as well as L-talo-2-amino-6-bromo-2,6-dideoxy-1,4-lactones ent-14 and ent-15, reacted accordingly to give the D-galacto- and L-altro-1,5-iminuronic acid mimetics, (2S,3S,4R,5S)-3,4,5-trihydroxypipecolic acid (2,6-dideoxy-2,6-imino-L-galactonic acid, ent-16) and (2R,3S,4R,5S)-3,4,5-trihydroxypipecolic...

  9. A nuclear radiation actuated valve for a nuclear reactor

    International Nuclear Information System (INIS)

    Christiansen, D.W.; Schively, D.P.

    1983-01-01

    The valve has a first part (such as a valve rod with piston) and a 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 which are different. The valve parts are 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. (author)

  10. Valve-gaping behavior of raft-cultivated mussels in the Ría de Arousa, Spain

    Directory of Open Access Journals (Sweden)

    Luc A. Comeau

    2018-02-01

    Full Text Available We describe the valve-opening behavior of raft-cultivated mussels (Mytilus galloprovincialis in the Ría de Arousa (Arousa estuary, Spain. Eight rope-grown mussels [mean ± standard error (SEM, shell length 61.6 ± 2.1 mm] were connected to a non-invasive valvometry apparatus that monitored (one measurement min−1 the magnitude of valve openness systematically over a 10 day period. It was found that valves were open 97.5 ± 1.3% percent of the time. Valve closures were not synchronized among the eight monitored mussels, suggesting that feeding cessation was physiologically-regulated rather than environmentally-mediated. The opening amplitudes that were most frequently observed were in the range of 60–90%, indicating that, when open, valves are usually opened relatively close to their maximum possible extent. The majority (7/8 of mussels displayed a circadian rhythm (τ = 24.0 h in valve opening amplitude. They tended to exhibit maximum valve opening during nighttime and minimum opening during daytime. It is possible that the light:dark cycle represents an environmental zeitgeber entraining an endogenous gaping rhythm in this bivalve.

  11. The boundary condition at the valve for numerical modelling of transient pipe flow with fluid structure interaction

    Science.gov (United States)

    Henclik, S.

    2014-08-01

    Transient flows in pipes (water hammer = WH) do appear in various situations and the accompanying pressure waves may involve serious perturbations in system functioning. To model these effects properly in the case of elastic pipe the dynamic fluid-structure interaction (FSI) should be taken into account. Fluid-structure couplings appear in various manners and the junction coupling is considered to be the strongest. This effect can be especially significant if the pipe can move as a whole body, which is possible when all its supports are not rigid. In the current paper a similar effect is numerically modelled. The pipe is fixed rigidly, but the valve at the end has a spring-dashpot mounting system, thus its motion is possible when WH is excited by the valve closuring. The boundary condition at the moving valve is modelled as a differential equation of motion. The valve hydraulic characteristics during closuring period are assumed by a time dependence of its loss factor. Preliminary numerical tests of that algorithm were done with an own computer program and it was found that the proper valve fixing system may produce significant lowering of WH pressures.

  12. Revisiting the Landau fluid closure.

    Science.gov (United States)

    Hunana, P.; Zank, G. P.; Webb, G. M.; Adhikari, L.

    2017-12-01

    Advanced fluid models that are much closer to the full kinetic description than the usual magnetohydrodynamic description are a very useful tool for studying astrophysical plasmas and for interpreting solar wind observational data. The development of advanced fluid models that contain certain kinetic effects is complicated and has attracted much attention over the past years. Here we focus on fluid models that incorporate the simplest possible forms of Landau damping, derived from linear kinetic theory expanded about a leading-order (gyrotropic) bi-Maxwellian distribution function f_0, under the approximation that the perturbed distribution function f_1 is gyrotropic as well. Specifically, we focus on various Pade approximants to the usual plasma response function (and to the plasma dispersion function) and examine possibilities that lead to a closure of the linear kinetic hierarchy of fluid moments. We present re-examination of the simplest Landau fluid closures.

  13. Observations on early and delayed colostomy closure.

    Science.gov (United States)

    Tade, A O; Salami, B A; Ayoade, B A

    2011-06-01

    Traditional treatment of a variety of colorectal pathologies had included a diverting colostomy that was closed eight or more weeks later during a readmission. The aim of this retrospective study was to determine the outcomes of early colostomy closure and delayed colostomy closure in patients with temporary colostomies following traumatic and non-traumatic colorectal pathologies. In this study early colostomy closure was the closure of a colostomy within three weeks of its construction, while delayed colostomy closure referred to closure after 3 weeks. Complete records of the 37 adult patients who had temporary colostomy constructed and closed between Jan. 1997 December 2003 for various colorectal pathologies were studied. Fourteen patients had early colostomy closure while 23 had delayed closure. In the early colostomy closure group there were 10 men and 4 women. The mean age of the patients was 28yr with a range of 18-65yr. Colostomies were closed 9-18 days after initial colostomy construction. There was no mortality. Morbidity rate 28.6% (4 out of 14). There were two faecal fistulas (14.3%). Twenty-three patients had delayed colostomy closure 8 weeks to 18 months after initial colostomy construction. These were patients unfit for early surgery after initial colostomy construction because of carcinoma, significant weight loss, or sepsis. There was no mortality. Morbidity rate was 26.1%. There were 3 faecal fistulas (13.2%). Outcomes following early colostomy closure and delayed closure were comparable. Patients fit for surgery should have early closure whilst patients who may have compromised health should have delayed closure.

  14. Double-lock technique: a simple method to secure abdominal wall closure

    International Nuclear Information System (INIS)

    Jategaonkar, P.A.; Yadav, S.P.

    2013-01-01

    Secure closure of a laparotomy incision remains an important aspect of any abdominal operation with the aim to avoid the postoperative morbidity and hasten the patient's recovery. Depending on the operator's preference and experience, it may be done by the continuous or the interrupted methods either using a non-absorbable or delayed-absorbable suture. We describe a simple, secure and quick technique of abdominal wall closure which involves continuous suture inter-locked doubly after every third bite. This simple and easy to use mass closure technique can be easily mastered by any member of the surgical team and does not need any assistant. It amalgamates the advantages of both, the continuous and the interrupted methods of closures. To our knowledge, such a technique has not been reported in the literature. (author)

  15. International Environmental Agreements: Emissions Trade, Safety Valves and Escape Clauses

    International Nuclear Information System (INIS)

    Karp, Larry; Zhao, Jinhua

    2010-01-01

    We explain how the structure of multi-national or multi-regional environmental agreements affect their chance of success. Trade in emissions permits has ambiguous and in some cases surprising effects on both the equilibrium level of abatement, and on the ability to persuade nations or regions to participate in environmental agreements. An escape clause policy and a safety valve policy have essentially the same properties when membership in environmental agreement is pre-determined, but they create markedly different effects on the incentives to join such an agreement. The two policies lead to a qualitative difference in the leverage that a potential member of the agreement exercises on other members

  16. Members of the Agency

    International Nuclear Information System (INIS)

    2007-01-01

    The new Member since the last list of Member States was issued (INFCIRC/2/Rev.63) is Palau which deposited its Instrument of Acceptance of the Statute on 2 March 2007. The Attachment hereto shows the dates on which the present 144 Member States became Members [fr

  17. Members of the Agency

    International Nuclear Information System (INIS)

    2007-01-01

    The new Member since the last list of Member States was issued (INFCIRC/2/Rev.63) is Palau which deposited its Instrument of Acceptance of the Statute on 2 March 2007. The Attachment hereto shows the dates on which the present 144 Member States became Members [es

  18. Small sodium valve design and operating experience

    International Nuclear Information System (INIS)

    Abramson, R.; Elie, X.; Vercasson, M.; Nedelec, J.

    1974-01-01

    Conventionally, valves for sodium pipes smaller than 125 mm in diameter are called ''small sodium valves''. However, this limit should rather be considered as the lower limit o ''large sodium valves''. In fact, both the largest sizes of small valves and the smallest of large valves can be found in the range of 125-300 mm in diameter. Thus what is said about small valves also applies, for a few valve types, above the 125 mm limit. Sodium valves are described here in a general manner, with no manufacturing details except when necessary for understanding valve behavior. Operating experience is pointed out wherever possible. Finally, some information is given about ongoing or proposed development plans. (U.S.)

  19. Design of the Modular Pneumatic Valve Terminal

    Directory of Open Access Journals (Sweden)

    Jakub E. TAKOSOGLU

    2015-11-01

    Full Text Available The paper presents design of the modular pneumatic valve terminal, which was made on the basis of the patent application No A1 402905 „A valve for controlling fluid power drives, specially for pneumatic actuators, and the control system for fluid power drives valves”. The authors describe a method of operation of the system with double-acting valve and 5/2 (five ways and two position valve. Functions of the valve, and an example of application of the valve terminal in the production process were presented. 3D solid models of all the components of the valve were made. The paper presents a complete 3D model of the valve in various configurations. Using CAD-embedded SOLIDWORKS Flow Simulation computational fluid dynamics CFD analysis was also carried out of compressed air flow in the ways of the valve elements

  20. Improved results of the vacuum assisted closure and Nitinol clips sternal closure after postoperative deep sternal wound infection.

    Science.gov (United States)

    Tocco, Maria Pia; Costantino, Alberto; Ballardini, Milva; D'Andrea, Claudio; Masala, Marcello; Merico, Eusebio; Mosillo, Luigi; Sordini, Paolo

    2009-05-01

    Postoperative deep sternal wound infection is a severe complication of cardiac surgery, with a high mortality rate and a high morbidity rate. The objective of this prospective study is to report our experience with the vacuum assisted closure (VAC) system for the management of deep wound infection. We also devised an innovative closure technique post VAC therapy using thermo reactive clips. The advantage of this technique is that the posterior face of the sternum does not have to be separated from the mediastinal structures thus minimising the risk of damage. From October 2006 to October 2008, we prospectively evaluated 21 patients affected by mediastinitis after sternotomy. Nineteen patients had sternotomy for coronary artery bypass grafting (CABG), one patient for aortic valve replacement (AVR) and another one for ascending aortic replacement (AAR). All patients were treated with the VAC system at the time of infection diagnosis. When the wound tissue appeared viable and the microbiological cultures were negative, the chest was closed using the most suitable procedure for the patient in question; nine patients were closed using pectoralis flaps, nine patients using Nitinol clips, one patient with a combined technique (use of Nitinol clips and muscle flap), one patient with a direct wound closure and another patient, who needed AAR with a homograft performed in another institution, was closed using sternal wires. We had no mortality; wound healing was successfully achieved in all patients. In more than 50% of the patients, the VAC therapy allowed direct sternal resynthesis. The average duration of the vacuum therapy was 26 days (range 14-37 days). VAC is a safe and effective option in the treatment of post-sternotomy mediastinitis, with excellent survival and immediate improvement of local wound conditions; furthermore, the use of Nitinol clips after VAC therapy demonstrated to be a safe and non-invasive option for sternal resynthesis. After VAC therapy, a

  1. Development of an effective valve packing program

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. 304 Concretion Facility Closure Plan

    International Nuclear Information System (INIS)

    1991-10-01

    The Hanford Site, located northwest of Richland, Washington, houses reactors, chemical-separation systems, and related facilities used for the production of special nuclear materials. The 300 Area of the Hanford Site contains reactor fuel manufacturing facilities and several research and development laboratories. Recyclable scrap uranium with Zircaloy-2 and copper silicon allo , uranium-titanium alloy, beryllium/Zircaloy-2 alloy, and Zircaloy-2 chips and fines were secured in concrete billets (7.5-gal containers) in the 304 Concretion Facility (304 Facility), located in the 300 Area. The beryllium/Zircaloy-2 alloy and Zircaloy-2 chips and fines are designated as low-level radioactive mixed waste (LLRMW) with the characteristic of ignitability. The concretion process reduced the ignitability of the fines and chips for safe storage and shipment. This process has been discontinued and the 304 Concretion Facility is now undergoing closure as defined in the Resource Conservation and Recovery Act of 1976 (RCRA) and the Washington Administrative Code (WAC) Dangerous Waste Regulations, WAC 173-303-040 (Ecology 1991). This closure plan presents a description of the facility, the history of materials and wastes managed, and the procedures that will be followed to close the 304 Facility. The strategy for closure of the 304 Facility is presented in Section 6.0

  3. Repository Closure and Sealing Approach

    International Nuclear Information System (INIS)

    A.T. Watkins

    2000-01-01

    The scope of this analysis will be to develop the conceptual design of the closure seals and their locations in the Subsurface Facilities. The design will be based on the recently established program requirements for transitioning to the Site Recommendation (SR) design as outlined by ''Approach to Implementing the Site Recommendation Baseline'' (Stroupe 2000) and the ''Monitored Geologic Repository Project Description Document'' (CRWMS M andO 1999b). The objective of this analysis will be to assist in providing a description for the Subsurface Facilities System Description Document, Section 2 and finally to document any conclusions reached in order to contribute and provide support to the SR. This analysis is at a conceptual level and is considered adequate to support the SR design. The final closure barriers and seals for the ventilation shafts, and the north and south ramps will require these openings to be permanently sealed to limit excessive air and water inflows and prevent human intrusion. The major tasks identified with closure in this analysis are: (1) Developing the overall subsurface seal layout and identifying design and operational interfaces for the Subsurface Facilities. (2) Summarizing the general site conditions and general rock characteristic with respect to seal location and describing the seal selected. (3) Identify seal construction materials, methodology of construction and strategic locations including design of the seal and plugs. (4) Discussing methods to prevent human intrusion

  4. Soft valves in plants

    Science.gov (United States)

    Park, Keunhwan; Tixier, Aude; Christensen, Anneline; Arnbjerg-Nielsen, Sif; Zwieniecki, Maciej; Jensen, Kaare

    2017-11-01

    Water and minerals flow from plant roots to leaves in the xylem, an interconnected network of vascular conduits that spans the full length of the organism. When a plant is subjected to drought stress, air pockets can spread inside the xylem, threatening the survival of the plant. Many plants prevent propagation of air by using hydrophobic nano-membranes in the ``pit'' pores that link adjacent xylem cells. This adds considerable resistance to flow. Interestingly, torus-margo pit pores in conifers are open and offer less resistance. To prevent propagation of air, conifers use a soft gating mechanism, which relies on hydrodynamic interactions between the xylem liquid and the elastic pit. However, it is unknown exactly how it is able to combine the seemingly antagonist functions of high permeability and resistance to propagation of air. We conduct experiments on biomimetic pores to elucidate the flow regulation mechanism. The design of plant valves is compared to other natural systems and optimal strategies are discussed. This work was supported by a research Grant (13166) from VILLUM FONDEN.

  5. Annular flow diverter valve

    International Nuclear Information System (INIS)

    Rider, R.L.

    1980-01-01

    A valve is described 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. It 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 sevomotor is 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

  6. Bioprosthetic Valve Fracture During Valve-in-valve TAVR: Bench to Bedside.

    Science.gov (United States)

    Saxon, John T; Allen, Keith B; Cohen, David J; Chhatriwalla, Adnan K

    2018-01-01

    Valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) has been established as a safe and effective means of treating failed surgical bioprosthetic valves (BPVs) in patients at high risk for complications related to reoperation. Patients who undergo VIV TAVR are at risk of patient-prosthesis mismatch, as the transcatheter heart valve (THV) is implanted within the ring of the existing BPV, limiting full expansion and reducing the maximum achievable effective orifice area of the THV. Importantly, patient-prosthesis mismatch and high residual transvalvular gradients are associated with reduced survival following VIV TAVR. Bioprosthetic valve fracture (BVF) is as a novel technique to address this problem. During BPV, a non-compliant valvuloplasty balloon is positioned within the BPV frame, and a highpressure balloon inflation is performed to fracture the surgical sewing ring of the BPV. This allows for further expansion of the BPV as well as the implanted THV, thus increasing the maximum effective orifice area that can be achieved after VIV TAVR. This review focuses on the current evidence base for BVF to facilitate VIV TAVR, including initial bench testing, procedural technique, clinical experience and future directions.

  7. Transition to turbulence in pulsatile flow through heart valves--a modified stability approach.

    Science.gov (United States)

    Bluestein, D; Einav, S

    1994-11-01

    The presence of turbulence in the cardiovascular system is generally an indication of some type of abnormality. Most cardiologists agree that turbulence near a valve indicates either valvular stenosis or regurgitation, depending on the phase of its occurrence during the cardiac cycle. As no satisfying analytical solutions of the stability of turbulent pulsatile flow exist, accurate, unbiased flow stability criteria are needed for the identification of turbulence initiation. The traditional approach uses a stability diagram based upon the stability of a plane Stokes layer where alpha (the Womersley parameter) is defined by the fundamental heart rate. We suggest a modified approach that involves the decomposition of alpha into its frequency components, where alpha is derived from the preferred modes induced on the flow by interaction between flow pulsation and the valve. Transition to turbulence in pulsatile flow through heart values was investigated in a pulse duplicator system using three polymer aortic valve models representing a normal aortic valve, a 65 percent stenosed valve and a 90 percent severely stenosed valve, and two mitral valve models representing a normal mitral valve and a 65 percent stenosed valve. Valve characteristics were closely simulated as to mimic the conditions that alter flow stability and initiate turbulent flow conditions. Valvular velocity waveforms were measured by laser Doppler anemometry (LDA). Spectral analysis was performed on velocity signals at selected spatial and temporal points to produce the power density spectra, in which the preferred frequency modes were identified. The spectra obtained during the rapid closure stage of the valves were found to be governed by the stenosis geometry. A shift toward higher dominant frequencies was correlated with the severity of the stenosis. According to the modified approach, stability of the flow is represented by a cluster of points, each corresponding to a specific dominant mode apparent

  8. An in vitro investigation of the retrograde flow fields of two bileaflet mechanical heart valves.

    Science.gov (United States)

    Ellis, J T; Healy, T M; Fontaine, A A; Weston, M W; Jarret, C A; Saxena, R; Yoganathan, A P

    1996-11-01

    Fluid stresses occurring in retrograde flow fields during valve closure may play a significant role in thrombogenesis. The squeeze flow and regurgitant jets can cause damage to formed blood elements due to high levels of turbulent shear stress. The aim of this study was to characterize in detail the spatial structure and temporal behavior of the retrograde flow fields of the St. Jude Medical and Medtronic Parallel bileaflet mechanical heart valves. Three-component, coincident laser Doppler anemometry (LDA) velocity measurements were obtained facilitating the determination of the full Reynolds stress tensor and the principal stresses in the valve flow fields. The experiments were performed in the Georgia Tech aortic flow chamber under physiologic pulsatile flow conditions. Data were collected over several hundred cardiac cycles for subsequent phase window averaging and generation of mean velocity and turbulence statistics over 20 ms intervals. A region approximately 8 mm x 10 mm was mapped 1.0 mm upstream of one hinge of each valve with an incremental resolution of 0.13-0.25 mm. Animation of the data allowed the visualization of the flow fields and a quantitative display of mean velocity and turbulent stress values. In the St. Jude Medical squeeze flow, the peak turbulent shear stress was 800 dynes/cm2 and the peak reverse velocity was 0.60 m/s. In the Medtronic Parallel squeeze flow, the peak turbulent shear stress was 1,000 dynes/cm2 and the peak velocity 0.70 m/s. The leakage jet fields of the two valves were very different: in the case of the St. Jude Medical valve, turbulent shear stresses reached 1,800 dynes/cm2 and peak jet velocity was 0.80 m/s; in the case of the Medtronic Parallel valve, turbulent shear stresses reached 3,690 dynes/cm2 and the peak jet velocity was 1.9 m/s. The retrograde flow fields of these two bileaflet mechanical heart valves appear to be design-dependent. The elevated turbulent shear stresses generated by both valve designs may

  9. Aortic valve-sparing operation in Marfan syndrome: what do we know after a decade?

    Science.gov (United States)

    Kallenbach, Klaus; Baraki, Hassina; Khaladj, Nawid; Kamiya, Hiroyuki; Hagl, Christian; Haverich, Axel; Karck, Matthias

    2007-02-01

    We assessed the outcome in patients with Marfan syndrome operated on exclusively with the aortic valve-sparing reimplantation technique for aortic root aneurysms during more than a decade. Between July 1993 and April 2005, the aortic valve-sparing reimplantation technique (David I) was used in 325 patients. In 59 patients with clinical evidence of Marfan syndrome, procedures were done for aortic root aneurysm (n = 55) or aortic dissection type A (n = 4). Their mean age was 30 +/- 12 years (range, 9 to 62 years), and 37 (63%) were male. Additional procedures were arch replacement in 4 patients, coronary artery bypass grafting in 1, mitral valve surgery in 9, and closure of atrial septal defect in 3. Mean follow-up was 54 +/- 37 months (range, 0 to 139 months). No patient died during the first 30 days postoperatively. Mean bypass time was 163 +/- 34 minutes (range, 99 to 248 minutes), and mean aortic cross clamp time was 126 +/- 28 minutes (range, 78 to 202 minutes). Four patients (6.8%) required rethoracotomy for postoperative bleeding. Five late deaths (8.5%) occurred during follow-up. Reoperation of the reconstructed valve was required in 7 patients. Freedom from reoperation was 88% +/- 5% at 5 years and 80% +/- 9% at 10 years. Mean grade of aortic insufficiency was 1.81 preoperatively compared with 0.20 early postoperatively (p valve should encourage use of this technique in patients with Marfan syndrome.

  10. Numerical Research on Flow Characteristics around a Hydraulic Turbine Runner at Small Opening of Cylindrical Valve

    Directory of Open Access Journals (Sweden)

    Zhenwei Mo

    2016-01-01

    Full Text Available We use the continuity equation and the Reynolds averaged Navier-Stokes equations to study the flow-pattern characteristics around a turbine runner for the small-opening cylindrical valve of a hydraulic turbine. For closure, we adopt the renormalization-group k-ε two-equation turbulence model and use the computational fluid dynamics (CFD software FLUENT to numerically simulate the three-dimensional unsteady turbulent flow through the entire passage of the hydraulic turbine. The results show that a low-pressure zone develops around the runner blades when the cylindrical valve is closed in a small opening; cavitation occurs at the blades, and a vortex appears at the outlet of the runner. As the cylindrical valve is gradually closed, the flow velocity over the runner area increases, and the pressure gradient becomes more significant as the discharge decreases. In addition, the fluid flow velocity is relatively high between the lower end of the cylindrical valve and the base, so that a high-velocity jet is easily induced. The calculation and analysis provide a theoretical basis for improving the performance of cylindrical-valve operating systems.

  11. LOFT pressurizer safety: relief valve reliability

    International Nuclear Information System (INIS)

    Brown, E.S.

    1978-01-01

    The LOFT pressurizer self-actuating safety-relief valves are constructed to the present state-of-the-art and should have reliability equivalent to the valves in use on PWR plants in the U.S. There have been no NRC incident reports on valve failures to lift that would challenge the Technical Specification Safety Limit. Fourteen valves have been reported as lifting a few percentage points outside the +-1% Tech. Spec. surveillance tolerance (9 valves tested over and 5 valves tested under specification). There have been no incident reports on failures to reseat. The LOFT surveillance program for assuring reliability is equivalent to nuclear industry practice

  12. Valve system incorporating single failure protection logic

    Science.gov (United States)

    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.

  13. LOFT pressurizer safety: relief valve reliability

    Energy Technology Data Exchange (ETDEWEB)

    Brown, E.S.

    1978-01-18

    The LOFT pressurizer self-actuating safety-relief valves are constructed to the present state-of-the-art and should have reliability equivalent to the valves in use on PWR plants in the U.S. There have been no NRC incident reports on valve failures to lift that would challenge the Technical Specification Safety Limit. Fourteen valves have been reported as lifting a few percentage points outside the +-1% Tech. Spec. surveillance tolerance (9 valves tested over and 5 valves tested under specification). There have been no incident reports on failures to reseat. The LOFT surveillance program for assuring reliability is equivalent to nuclear industry practice.

  14. Velocity measurements and flow patterns within the hinge region of a Medtronic Parallel bileaflet mechanical valve with clear housing.

    Science.gov (United States)

    Ellis, J T; Healy, T M; Fontaine, A A; Saxena, R; Yoganathan, A P

    1996-11-01

    During recent clinical trials the Medtronic Parallel bileaflet mechanical heart valve was found to have an unacceptable number of valves with thrombus formation when implanted in the mitral position. Thrombi were observed in the hinge region and also in the upstream portion of the valve housing in the vicinity of the hinge. It was hypothesized that the flow conditions inside the hinge may have contributed to the thrombus formation. In order to investigate the flow structures within the hinge, laser Doppler anemometry (LDA) measurements were conducted in both steady and pulsatile flow at approximately 70 predetermined sites within the hinge region of a 27 mm Medtronic Parallel mitral valve with transparent housing. The pulsatile flow velocity measurements were animated in time using a graphical software package to visualize the hinge flow field throughout the cardiac cycle. The LDA measurements revealed that mean forward flow velocities through the hinge region were on the order of 0.10-0.20 m/s. In the inflow channel, a large vortical structure was present during diastole. Upon valve closure, peak reverse velocity reached 3 m/s close to the housing wall in the inflow channel. This area also experienced high turbulent shear stresses (> 6000 dynes/cm2) during the leakage flow phase. A disturbed, vortical flow was again present in the inflow channel after valve closure, while slightly above the leaflet peg and relief the flow was essentially stagnant. The high turbulent stresses near the top of the inflow channel, combined with a persistent vortex, implicate the inflow channel of the hinge as a likely region of thrombus formation. This experimental investigation revealed zones of flow stagnation in the inflow region of the hinge throughout the cardiac cycle and elevated turbulent shear stress levels in the inflow region during the leakage flow phase. These fluid mechanic phenomena are most likely a direct result of the complex geometry of the hinge of this valve

  15. Butterfly valve of all rubber lining type

    International Nuclear Information System (INIS)

    Shimada, Shosaku; Nakatsuma, Sumiya; Sasaki, Iwao; Aoki, Naoshi.

    1982-01-01

    The valves used for the circulating water pipes for condensers in nuclear and thermal power stations have become large with the increase of power output, and their specifications have become strict. The materials for the valves change from cast iron to steel plate construction. To cope with sea water corrosion, rubber lining has been applied to the internal surfaces of valve boxes, and the build-up welding of stainless steel has been made on the edges of valves. However, recently it is desired to develop butterfly valves, of which the whole valve disks are lined with hard rubber. For the purpose of confirming the performance of large bore valves, a 2600 mm bore butterfly valve of all rubber lining type was used, and the opening and closing test of 1100 times was carried out by applying thermal cycle and pressure difference and using artifical sea water. Also the bending test of hard rubber lining was performed with test pieces. Thus, it was confirmed that the butterfly valves of all rubber lining type have the performance exceeding that of the valves with build-up welding. The course of development of the valves of all rubber lining type, the construction and the items of confirmation by tests of these valves, and the tests of the valve and the hard rubber lining described above are reported. (Kako, I.)

  16. Door valve for fuel handling path

    International Nuclear Information System (INIS)

    Makishima, Katsuhiko.

    1969-01-01

    A door valve is provided which seals cover gas from a liquid metal cooled reactor without leakage therefrom. A threaded shaft is screwed into a heavy box press which is packed with lead. The shaft is adapted to be rotated by an electric motor or a manually operated wheel which is disposed outside of the door valve. A valve plate is suspended from the box press by four guide wheels mounted thereon. The guide wheels are fitted into inclined guide grooves formed at the valve plate and into grooved formed in the inner wall of a valve casing. A locking ball is provided at each side of the valve plate. In operation the shaft rotates and travels to permit the box press and the valve plate to move into the door valve casing, thus releasing the locking balls. The valve plate does not contact the bottom of the casing. When the box press reaches the home position, the valve plate is carried on the valve opening, and the box press presses the valve plate to increase the tightness. The valve plate does not suffer wear as it does not slide over other parts. (Yamaguchi, T.)

  17. Sequential transcatheter aortic valve implantation due to valve dislodgement - a Portico valve implanted over a CoreValve bioprosthesis.

    Science.gov (United States)

    Campante Teles, Rui; Costa, Cátia; Almeida, Manuel; Brito, João; Sondergaard, Lars; Neves, José P; Abecasis, João; M Gabriel, Henrique

    2017-03-01

    Transcatheter aortic valve implantation (TAVI) has become an important treatment in high surgical risk patients with severe aortic stenosis (AS), whose complications need to be managed promptly. The authors report the case of an 86-year-old woman presenting with severe symptomatic AS, rejected for surgery due to advanced age and comorbidities. The patient underwent a first TAVI, with implantation of a Medtronic CoreValve ® , which became dislodged and migrated to the ascending aorta. Due to the previous balloon valvuloplasty, the patient's AS became moderate, and her symptoms improved. After several months, she required another intervention, performed with a St. Jude Portico ® repositionable self-expanding transcatheter aortic valve. There was a good clinical response that was maintained at one-year follow-up. The use of a self-expanding transcatheter bioprosthesis with repositioning features is a solution in cases of valve dislocation to avoid suboptimal positioning of a second implant, especially when the two valves have to be positioned overlapping or partially overlapping each other. Copyright © 2017 Sociedade Portuguesa de Cardiologia. Publicado por Elsevier España, S.L.U. All rights reserved.

  18. Cavitation noise from butterfly valves

    International Nuclear Information System (INIS)

    Rahmeyer, W.J.

    1982-01-01

    Cavitation in valves can produce levels of intense noise. It is possible to mathematically express a limit for a design level of cavitation noise in terms of the cavitation parameter sigma. Using the cavitation parameter or limit, it is then possible to calculate the flow conditions at which a design level of cavitation noise will occur. However, the intensity of cavitation increases with the upstream pressure and valve size at a constant sigma. Therefore, it is necessary to derive equations to correct or scale the cavitation limit for the effects of different upstream pressures and valve sizes. The following paper discusses and presents experimental data for the caviation noise limit as well as the cavitation limits of incipient, critical, incipient damage, and choking cavitation for butterfly valves. The main emphasis is on the design limit of caviation noise, and a noise level of 85 decibels was selected as the noise limit. Tables of data and scaling exponents are included for applying the design limits for the effects of upstream pressure and valve size. (orig.)

  19. Plunger with simple retention valve

    International Nuclear Information System (INIS)

    Fekete, A.V.

    1987-01-01

    This patent describes a positive displacement retention valve apparatus in which the actual flow equals the theoretical maximum flow through the retention valve. The apparatus includes, in combination, a confined fluid flow conduit, a piston adapted for reciprocal movement within the fluid flow conduit between upstream and downstream limit positions, piston reciprocating means, and pressure responsive check valve means located upstream with respect to the piston in the fluid flow conduit. The pressure responsive check valve means operable to permit fluid flow therethrough in a downstream direction toward the piston, and to preclude fluid flow therethrough in an opposite direction. The piston is composed of parts which are relatively movable with respect to one another. The piston includes a simple retention valve consisting of a plug means, a cylinder having a minimum and a maximum internal cross section flow area therein and being reciprocal within the confined fluid flow conduit, and a seat on the cylinder for the plug means. The piston reciprocating means are operatively connected to the plug means

  20. Explosive actuated valve

    International Nuclear Information System (INIS)

    Byrne, K.G.

    1983-01-01

    1. A device of the character described comprising the combination of a housing having an elongate bore and including a shoulder extending inwardly into said bore, a single elongate movable plunger disposed in said bore including an outwardly extending flange adjacent one end thereof overlying said shoulder, normally open conduit means having an inlet and an outlet perpendicularly piercing said housing intermediate said shoulder and said flange and including an intermediate portion intersecting and normally openly communicating with said bore at said shoulder, normally closed conduit means piercing said housing and intersecting said bore at a location spaced from said normally open conduit means, said elongate plunger including a shearing edge adjacent the other end thereof normally disposed intermediate both of said conduit means and overlying a portion of said normally closed conduit means, a deformable member carried by said plunger intermediate said flange and said shoulder and normally spaced from and overlying the intermediate portion of said normally open conduit means, and means on the housing communicating with the bore to retain an explosive actuator for moving said plunger to force the deformable member against the shoulder and extrude a portion of the deformable member out of said bore into portions of the normally open conduit means for plugging the same and to effect the opening of said normally closed conduit means by the plunger shearing edge substantially concomitantly with the plugging of the normally open conduit means

  1. In utero premature closure of the ductus arteriosus presenting as isolated right ventricular hypertrophy.

    Science.gov (United States)

    Long, Webb E; Wilson, Allen D; Srinivasan, Shardha; Seeger, Kimberly J; Maginot, Kathleen R

    2009-10-01

    The etiology of isolated right ventricular hypertrophy (RVH) is distinct from other forms of hypertrophic cardiomyopathy. RVH is typically seen in the setting of pulmonary valve stenosis or Tetralogy of Fallot. A rare cause of isolated RVH is premature closure of the patent ductus arteriosus (PDA) in utero that results in pulmonary hypertension. This can have a range of outcomes, from spontaneous resolution to fetal demise. This case report describes a term infant who presented with respiratory distress and striking isolated RVH, pulmonary hypertension, and no PDA. She was treated conservatively with supplemental oxygen. The patient was gradually weaned off oxygen over the course of two weeks and follow-up echocardiography showed resolution of her RVH and pulmonary hypertension by 14 weeks of age. The presentation and course of this patient with severe isolated RVH is consistent with spontaneous premature closure of the ductus arteriosus in utero.

  2. Structural valve deterioration in the Mitroflow biological heart valve prosthesis

    DEFF Research Database (Denmark)

    Issa, Issa Farah; Poulsen, Steen Hvitfeldt; Waziri, Farhad

    2018-01-01

    OBJECTIVES: Concern has been raised regarding the long-term durability of the Mitroflow biological heart valve prosthesis. Our aim was to assess the incidence of structural valve degeneration (SVD) for the Mitroflow bioprosthesis in a nationwide study in Denmark including all patients alive......: A total of 173 patients were diagnosed with SVD by echocardiography. Of these, 64 (11%) patients had severe SVD and 109 (19%) patients moderate SVD. Severe SVD was associated with the age of the prosthesis and small prosthesis size [Size 21: hazard ratio (95% confidence interval, CI) 2.72 (0.97-8.56), P...

  3. Residual Heat Removal System qualitative probabilistic safety analysis before and after auto closure interlock removal

    International Nuclear Information System (INIS)

    Mikulicic, V.; Simic, Z.

    1992-01-01

    The analysis evaluates the consequences of the removal of the auto closure interlock (ACI) on the Residual Heat Removal System (RHRS) suction/isolation valves at the nuclear power plant. The deletion of the RHRS ACI is in part based on a probabilistic safety analysis (PSA) which justifies the removal based on a criterion of increased availability and reliability. Three different areas to be examined in PSA: the likelihood of an interfacing system LOCA; RHRS availability and reliability; and low temperature overpressurization control. The paper emphasizes particularly the RHRS unavailability and reliability evaluation utilizing the current control circuitry configuration and then with the proposed modification to the control circuitry. (author)

  4. Bicuspid Aortic Valve Disease: A Comprehensive Review

    OpenAIRE

    Mordi, Ify; Tzemos, Nikolaos

    2012-01-01

    Bicuspid aortic valve is the commonest congenital cardiac abnormality in the general population. This paper article will discuss our current knowledge of the anatomy, pathophysiology, genetics, and clinical aspects of bicuspid aortic valve disease.

  5. Echocardiographic evaluation of heart valve prosthetic dysfunction

    Directory of Open Access Journals (Sweden)

    Yuriy Ivaniv

    2018-02-01

    Full Text Available Patients with replaced heart valve submitted to echocardiographic examination may have symptoms related either to valvular malfunction or ventricular dysfunction from different causes. Clinical examination is not reliable in a prosthetic valve evaluation and the main information regarding its function could be obtained using different cardiac ultrasound modalities. This review provides a description of echocardiographic and Doppler techniques useful in evaluation of prosthetic heart valves. For the interpretation of echocardiography there is a need in special knowledge of prosthesis types and possible reasons of prosthetic function deterioration. Echocardiography allows to reveal valve thrombosis, pannus formation, vegetation and such complications of infective endocarditis as valve ring abscess or dehiscence. Transthoracic echocardiography requires different section plane angles and unconventional views. Transesophageal echocardiography is more often used than in native valve examination due to better visualization of prosthetic valve structure and function. Three-dimensional echocardiography could provide more detailed visual information especially in the assessment of paravalvular regurgitation or valve obstruction.

  6. Bistable fluidic valve is electrically switched

    Science.gov (United States)

    Fiet, O.; Salvinski, R. J.

    1970-01-01

    Bistable control valve is selectively switched by direct application of an electrical field to divert fluid from one output channel to another. Valve is inexpensive, has no moving parts, and operates on fluids which are relatively poor electrical conductors.

  7. Comparative study between CardiaMed valves (freely floating valve leaflets versus St. Jude Medical (fixed valve leaflets in mitral valve replacement surgery

    Directory of Open Access Journals (Sweden)

    Mostafa Ahmed

    2017-09-01

    Conclusions: CardiaMed freely floating leaflet prostheses showed good hemodynamic characteristics. The prosthesis adequately corrects hemodynamics and is safe and no worse than the St. Jude Medical valve in the mitral valve position.

  8. Don’t call it a closure!

    CERN Document Server

    Rosaria Marraffino

    2015-01-01

    During the Laboratory’s annual closure, some members of the personnel joined their families, others seized the chance to travel the world. The Restaurants were closed, the corridors were dark and the heating was turned off in most of the buildings. However, a lot of people spent the Christmas break working on site and the Bulletin would like to dedicate this first article of the new year to them all!   In the CERN Control Centre (CCC), each shift had two people in position to guarantee regular 24/7 service and to intervene in case of need. Gildas Langlois and Rodolphe Maillet, CCC operators from the Beams Department, spent Christmas Eve there and celebrated it with a cake. “I volunteered to work during the holidays in order to allow colleagues to stay with their families,” says Maillet. On New Year’s Eve, it was Julien Pache and Jean-Michel Nonglaton’s turn to spend the night at work. They had a nice dinner with a CCC-made fondue and some desse...

  9. Storage shaft definitive closure plug and method

    International Nuclear Information System (INIS)

    Dardaine, M.

    1992-01-01

    A definitive closure plug system for radioactive waste storage at any deepness, is presented. The inherent weight of the closure materials is used to set in the plug: these materials display an inclined sliding surface in such a way that when the closure material rests on a stable surface of the shaft storage materials, the relative sliding of the different materials tends to spread them towards the shaft internal wall so as to completely occlude the shaft

  10. Prosthetic Mitral Valve Leaflet Escape

    Science.gov (United States)

    Kim, Darae; Hun, Sin Sang; Cho, In-Jeong; Shim, Chi-Young; Ha, Jong-Won; Chung, Namsik; Ju, Hyun Chul; Sohn, Jang Won

    2013-01-01

    Leaflet escape of prosthetic valve is rare but potentially life threatening. It is essential to make timely diagnosis in order to avoid mortality. Transesophageal echocardiography and cinefluoroscopy is usually diagnostic and the location of the missing leaflet can be identified by computed tomography (CT). Emergent surgical correction is mandatory. We report a case of fractured escape of Edward-Duromedics mitral valve 27 years after the surgery. The patient presented with symptoms of acute decompensated heart failure and cardiogenic shock. She was instantly intubated and mechanically ventilated. After prompt evaluation including transthoracic echocardiography and CT, the escape of the leaflet was confirmed. The patient underwent emergent surgery for replacement of the damaged prosthetic valves immediately. Eleven days after the surgery, the dislodged leaflet in iliac artery was removed safely and the patient recovered well. PMID:23837121

  11. Active combustion flow modulation valve

    Science.gov (United States)

    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.

  12. Statins for aortic valve stenosis

    Directory of Open Access Journals (Sweden)

    Luciana Thiago

    Full Text Available ABSTRACT BACKGROUND: Aortic valve stenosis is the most common type of valvular heart disease in the USA and Europe. Aortic valve stenosis is considered similar to atherosclerotic disease. Some studies have evaluated statins for aortic valve stenosis. OBJECTIVES: To evaluate the effectiveness and safety of statins in aortic valve stenosis. METHODS: Search methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL, MEDLINE, Embase, LILACS - IBECS, Web of Science and CINAHL Plus. These databases were searched from their inception to 24 November 2015. We also searched trials in registers for ongoing trials. We used no language restrictions. Selection criteria: Randomized controlled clinical trials (RCTs comparing statins alone or in association with other systemic drugs to reduce cholesterol levels versus placebo or usual care. Data collection and analysis: Primary outcomes were severity of aortic valve stenosis (evaluated by echocardiographic criteria: mean pressure gradient, valve area and aortic jet velocity, freedom from valve replacement and death from cardiovascular cause. Secondary outcomes were hospitalization for any reason, overall mortality, adverse events and patient quality of life. Two review authors independently selected trials for inclusion, extracted data and assessed the risk of bias. The GRADE methodology was employed to assess the quality of result findings and the GRADE profiler (GRADEPRO was used to import data from Review Manager 5.3 to create a 'Summary of findings' table. MAIN RESULTS: We included four RCTs with 2360 participants comparing statins (1185 participants with placebo (1175 participants. We found low-quality evidence for our primary outcome of severity of aortic valve stenosis, evaluated by mean pressure gradient (mean difference (MD -0.54, 95% confidence interval (CI -1.88 to 0.80; participants = 1935; studies = 2, valve area (MD -0.07, 95% CI -0.28 to 0.14; participants = 127; studies = 2

  13. Statins for aortic valve stenosis.

    Science.gov (United States)

    Thiago, Luciana; Tsuji, Selma Rumiko; Nyong, Jonathan; Puga, Maria Eduarda Dos Santos; Góis, Aécio Flávio Teixeira de; Macedo, Cristiane Rufino; Valente, Orsine; Atallah, Álvaro Nagib

    2016-01-01

    Aortic valve stenosis is the most common type of valvular heart disease in the USA and Europe. Aortic valve stenosis is considered similar to atherosclerotic disease. Some studies have evaluated statins for aortic valve stenosis. To evaluate the effectiveness and safety of statins in aortic valve stenosis. Search methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, LILACS - IBECS, Web of Science and CINAHL Plus. These databases were searched from their inception to 24 November 2015. We also searched trials in registers for ongoing trials. We used no language restrictions.Selection criteria: Randomized controlled clinical trials (RCTs) comparing statins alone or in association with other systemic drugs to reduce cholesterol levels versus placebo or usual care. Data collection and analysis: Primary outcomes were severity of aortic valve stenosis (evaluated by echocardiographic criteria: mean pressure gradient, valve area and aortic jet velocity), freedom from valve replacement and death from cardiovascular cause. Secondary outcomes were hospitalization for any reason, overall mortality, adverse events and patient quality of life.Two review authors independently selected trials for inclusion, extracted data and assessed the risk of bias. The GRADE methodology was employed to assess the quality of result findings and the GRADE profiler (GRADEPRO) was used to import data from Review Manager 5.3 to create a 'Summary of findings' table. We included four RCTs with 2360 participants comparing statins (1185 participants) with placebo (1175 participants). We found low-quality evidence for our primary outcome of severity of aortic valve stenosis, evaluated by mean pressure gradient (mean difference (MD) -0.54, 95% confidence interval (CI) -1.88 to 0.80; participants = 1935; studies = 2), valve area (MD -0.07, 95% CI -0.28 to 0.14; participants = 127; studies = 2), and aortic jet velocity (MD -0.06, 95% CI -0.26 to 0

  14. Evaluation of mispositioned ECCS valves

    International Nuclear Information System (INIS)

    Hill, R.A.; O'Brien, J.F.; McIntire, D.C.; Barlow, R.T.

    1977-09-01

    In October of 1975, Westinghouse submitted NS-CE-787, dated October 17, 1975, to the Nuclear Regulatory Commission (NRC) and entered into discussions with them concerning the spurious movement of certain motor-operated valves (MOV's) in the Emergency Core Cooling System (ECCS) to a position defeating the ECCS function at a time when this function is required. On November 25, 1975, the discussion turned to the possible movement of a manually controlled, motor-operated valve due to a fault in its electrical circuitry and the NRC staff expressed concerns about other possible failure modes that might lead to such a valve movement. The NRC meeting minutes document these concerns. This report is an item-by-item response to the concerns expressed by the NRC staff at that meeting and incorporates the original electrical fault analysis

  15. Novel Active Combustion Control Valve

    Science.gov (United States)

    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.

  16. Pannus Formation Leads to Valve Malfunction in the Tricuspid Position 19 Years after Triple Valve Replacement.

    Science.gov (United States)

    Alskaf, Ebraham; McConkey, Hannah; Laskar, Nabila; Kardos, Attila

    2016-06-20

    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.

  17. The nordic aortic valve intervention (NOTION) trial comparing transcatheter versus surgical valve implantation

    DEFF Research Database (Denmark)

    Thyregod, Hans Gustav; Søndergaard, Lars; Ihlemann, Nikolaj

    2013-01-01

    Degenerative aortic valve (AV) stenosis is the most prevalent heart valve disease in the western world. Surgical aortic valve replacement (SAVR) has until recently been the standard of treatment for patients with severe AV stenosis. Whether transcatheter aortic valve implantation (TAVI) can...

  18. Early clinical outcome of aortic transcatheter valve-in-valve implantation in the Nordic countries

    DEFF Research Database (Denmark)

    Ihlberg, Leo; Nissen, Henrik Hoffmann; Nielsen, Niels Erik

    2013-01-01

    Transcatheter valve-in-valve implantation has emerged as an option, in addition to reoperative surgical aortic valve replacement, to treat failed biologic heart valve substitutes. However, the clinical experience with this approach is still limited. We report the comprehensive experience...

  19. Intro to Valve Guide Reconditioning. Automotive Mechanics. Valves. Instructor's Guide [and] Student Guide.

    Science.gov (United States)

    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…

  20. Infective Endocarditis of the Aortic Valve with Anterior Mitral Valve Leaflet Aneurysm

    NARCIS (Netherlands)

    Tomsic, Anton; Li, Wilson W. L.; van Paridon, Marieke; Bindraban, Navin R.; de Mol, Bas A. J. M.

    2016-01-01

    Mitral valve leaflet aneurysm is a rare and potentially devastating complication of aortic valve endocarditis. We report the case of a 48-year-old man who had endocarditis of the native aortic valve and a concomitant aneurysm of the anterior mitral valve leaflet. Severe mitral regurgitation occurred

  1. 100-D Ponds closure plan. Revision 1

    International Nuclear Information System (INIS)

    Petersen, S.W.

    1997-09-01

    The 100-D Ponds is a Treatment, Storage, and Disposal (TSD) unit on the Hanford Facility that received both dangerous and nonregulated waste. This Closure Plan (Rev. 1) for the 100-D Ponds TSD unit consists of a RCRA Part A Dangerous Waste Permit Application (Rev. 3), a RCRA Closure Plan, and supporting information contained in the appendices to the plan. The closure plan consists of eight chapters containing facility description, process information, waste characteristics, and groundwater monitoring data. There are also chapters containing the closure strategy and performance standards. The strategy for the closure of the 100-D Ponds TSD unit is clean closure. Appendices A and B of the closure plan demonstrate that soil and groundwater beneath 100-D Ponds are below cleanup limits. All dangerous wastes or dangerous waste constituents or residues associated with the operation of the ponds have been removed, therefore, human health and the environment are protected. Discharges to the 100-D Ponds, which are located in the 100-DR-1 operable unit, were discontinued in June 1994. Contaminated sediment was removed from the ponds in August 1996. Subsequent sampling and analysis demonstrated that there is no contamination remaining in the ponds, therefore, this closure plan is a demonstration of clean closure

  2. Closure Welding of Plutonium Bearing Storage Containers

    International Nuclear Information System (INIS)

    Cannell, G.R.

    2002-01-01

    A key element in the Department of Energy (DOE) strategy for the stabilization, packaging and storage of plutonium-bearing materials involves closure welding of DOE-STD-3013 Outer Containers (3013 container). The 3013 container provides the primary barrier and pressure boundary preventing release of plutonium-bearing materials to the environment. The final closure (closure weld) of the 3013 container must be leaktight, structurally sound and meet DOE STD 3013 specified criteria. This paper focuses on the development, qualification and demonstration of the welding process for the closure welding of Hanford PFP 3013 outer containers

  3. Small sodium valve design and operating experience

    International Nuclear Information System (INIS)

    McGough, C.B.

    1974-01-01

    The United States Liquid Metal Fast Breeder Reactor program (LMFBR) includes an extensive program devoted to the development of small sodium valves. This program is now focused on the development and production of valves for the Fast Flux Test Facility (FFTF) now under construction near Richland, Washington. Other AEC support facilities, such as various test loops located at the Liquid Metal Engineering Center (LMEC), Los Angeles, California, and at the Hanford Engineering Development Laboratory (HEDL), Richland, Washington, also have significant requirements for small sodium valves, and valves similar in design to the FFTF valves are being supplied to these AEC laboratories for use in their critical test installations. A principal motivation for these valve programs, beyond the immediate need to provide high-reliability valves for FFTF and the support facilities, is the necessity to develop small valve technology for the Clinch River Breeder Reactor Plant (CRBRP). FFTF small sodium valve design and development experience will be directly applied to the CRBRP program. Various test programs have been, and are being, conducted to verify the performance and integrity of the FFTF valves, and to uncover any potential problems so that they can be corrected before the valves are placed in service in FFTF. The principal small sodium valve designs being utilized in current U.S. programs, the test and operational experience obtained to date on them, problems uncovered, and future development and testing efforts being planned are reviewed. The standards and requirements to which the valves are being designed and fabricated, the valve designs in current use, valve operators, test and operating experience, and future valve development plans are summarized. (U.S.)

  4. Promising results after percutaneous mitral valve repair

    DEFF Research Database (Denmark)

    Ihlemann, Nikolaj; Franzen, Olaf; Jørgensen, Erik

    2011-01-01

    Mitral valve regurgitation (MR) is the secondmost frequent valve disease in Europe. Untreated MR causes considerable morbidity and mortality. In the elderly, as many as half of these patients are denied surgery because of an estimated high surgical risk. Percutaneous mitral valve repair with the ...... with the MitraClip system resembles the Alfieristitch where a clip is used to connect the tip of the mitral valve leaflets....

  5. Infective endocarditis following percutaneous pulmonary valve replacement

    DEFF Research Database (Denmark)

    Cheung, Gary; Vejlstrup, Niels; Ihlemann, Nikolaj

    2013-01-01

    Infective endocarditis (IE) following percutaneous pulmonary valve replacement (PPVR) with the Melody valve is rarely reported. Furthermore, there are challenges in this diagnosis; especially echocardiographic evidence of vegetation within the prosthesis may be difficult.......Infective endocarditis (IE) following percutaneous pulmonary valve replacement (PPVR) with the Melody valve is rarely reported. Furthermore, there are challenges in this diagnosis; especially echocardiographic evidence of vegetation within the prosthesis may be difficult....

  6. Fast-acting valve actuator

    Science.gov (United States)

    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.

  7. Effects of the blockage ratio of a valve disk on loss coefficient in a butterfly valve

    International Nuclear Information System (INIS)

    Rho, Hyung Joon; Lee, Jee Keun; Choi, Hee Joo

    2008-01-01

    The loss coefficient of the butterfly valve which allows partial opening of the valve at closed position and is applicable to the small-sized pipe system with the diameter of 1 inch was measured for the variation of the valve disk blockage ratio. Two different types of the valve disk configuration to adjust the blockage ratio were considered. One was the solid type valve disk of which the diameter was changed into the smaller size rather than the pipe diameter, and the other was the perforate type valve disk on which some holes were perforated. The results from two types of valve disk were compared to identify their characteristics in the loss coefficient distributions. The loss coefficient and the controllable angle of the valve disk were decreased exponentially with the decrease of the blockage ratio. In addition, the perforate valve disk had the effect on the higher loss coefficient rather than the solid type valve disk

  8. High-resolution subject-specific mitral valve imaging and modeling: experimental and computational methods.

    Science.gov (United States)

    Toma, Milan; Bloodworth, Charles H; Einstein, Daniel R; Pierce, Eric L; Cochran, Richard P; Yoganathan, Ajit P; Kunzelman, Karyn S

    2016-12-01

    The diversity of mitral valve (MV) geometries and multitude of surgical options for correction of MV diseases necessitates the use of computational modeling. Numerical simulations of the MV would allow surgeons and engineers to evaluate repairs, devices, procedures, and concepts before performing them and before moving on to more costly testing modalities. Constructing, tuning, and validating these models rely upon extensive in vitro characterization of valve structure, function, and response to change due to diseases. Micro-computed tomography ([Formula: see text]CT) allows for unmatched spatial resolution for soft tissue imaging. However, it is still technically challenging to obtain an accurate geometry of the diastolic MV. We discuss here the development of a novel technique for treating MV specimens with glutaraldehyde fixative in order to minimize geometric distortions in preparation for [Formula: see text]CT scanning. The technique provides a resulting MV geometry which is significantly more detailed in chordal structure, accurate in leaflet shape, and closer to its physiological diastolic geometry. In this paper, computational fluid-structure interaction (FSI) simulations are used to show the importance of more detailed subject-specific MV geometry with 3D chordal structure to simulate a proper closure validated against [Formula: see text]CT images of the closed valve. Two computational models, before and after use of the aforementioned technique, are used to simulate closure of the MV.

  9. Closure for spent-fuel transport and storage containers

    International Nuclear Information System (INIS)

    Ahner, S.; Knackstedt, H.G.; Srostlik, P.

    1980-01-01

    The container has a transport closure and a shielding closure. This shielding closure consists of two pieces (double closure system), which can be fartened to one another like a bayonet fixing. A central motion of rotation is enough to open the closure. It can be done remote-controlled as well as manually. (DG) [de

  10. 49 CFR 195.260 - Valves: Location.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valves: Location. 195.260 Section 195.260... PIPELINE Construction § 195.260 Valves: Location. A valve must be installed at each of the following locations: (a) On the suction end and the discharge end of a pump station in a manner that permits isolation...

  11. Porcine Tricuspid Valve Anatomy and Human Compatibility

    DEFF Research Database (Denmark)

    Waziri, Farhad; Lyager Nielsen, Sten; Hasenkam, J. Michael

    2016-01-01

    before clinical use. The study aim was to evaluate and compare the tricuspid valve anatomy of porcine and human hearts. METHODS: The anatomy of the tricuspid valve and the surrounding structures that affect the valve during a cardiac cycle were examined in detail in 100 fresh and 19 formalin...

  12. Valve-sparing aortic root replacement†

    NARCIS (Netherlands)

    Koolbergen, David R.; Manshanden, Johan S. J.; Bouma, Berto J.; Blom, Nico A.; Mulder, Barbara J. M.; de Mol, Bas A. J. M.; Hazekamp, Mark G.

    2015-01-01

    To evaluate our results of valve-sparing aortic root replacement and associated (multiple) valve repair. From September 2003 to September 2013, 97 patients had valve-sparing aortic root replacement procedures. Patient records and preoperative, postoperative and recent echocardiograms were reviewed.

  13. Solving the problem of valve stem leakage

    International Nuclear Information System (INIS)

    Dixon, D.F.

    1976-01-01

    Engineering solutions to valve stem leakage, in systems carrying expensive heavy water under pressure, have progressed from changing packing brands (failure) to leak collection (partial success) to elimination of small packed valves and an improved valve packing strategy involving stable packing materials, live Belleville spring-loading of packing, and issuance of a detailed stuffing box specification (success). (E.C.B.)

  14. 49 CFR 229.109 - Safety valves.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Safety valves. 229.109 Section 229.109..., DEPARTMENT OF TRANSPORTATION RAILROAD LOCOMOTIVE SAFETY STANDARDS Safety Requirements Steam Generators § 229.109 Safety valves. Every steam generator shall be equipped with at least two safety valves that have a...

  15. Miniature piezo electric vacuum inlet valve

    Science.gov (United States)

    Keville, Robert F.; Dietrich, Daniel D.

    1998-03-24

    A miniature piezo electric vacuum inlet valve having a fast pulse rate and is battery operated with variable flow capability. The low power (piezo electric valves which require preloading of the crystal drive mechanism and 120 Vac, thus the valve of the present invention is smaller by a factor of three.

  16. Valve Corporation: Strategy Tipping Points and Thresholds

    OpenAIRE

    Teppo Felin

    2015-01-01

    Valve Corporation represents an intriguing case study of flat structure and self organization (Puranam & Håkonsson, 2015; Valve, 2012).  The structures and practices of Valve of course are not new. But the company provides an interesting experiment and illustration that powerfully highlights how organizational design can impact individual and collective behavior, strategy and performance.

  17. Valve Corporation: Strategy Tipping Points and Thresholds

    Directory of Open Access Journals (Sweden)

    Teppo Felin

    2015-06-01

    Full Text Available Valve Corporation represents an intriguing case study of flat structure and self organization (Puranam & Håkonsson, 2015; Valve, 2012.  The structures and practices of Valve of course are not new. But the company provides an interesting experiment and illustration that powerfully highlights how organizational design can impact individual and collective behavior, strategy and performance.

  18. Door valve for fuel handling path

    International Nuclear Information System (INIS)

    Makishima, Katsuhiko.

    1969-01-01

    A door valve is provided which seals cover gas from a liquid metal cooled reactor without leakage therefrom. A threaded shaft is screwed into a heavy box press which is packed with lead. The shaft is adapted to be rotated by an electric motor or a manually operated wheel which is disposed outside of the door valve. From the box press a valve plate is suspended by four linkage bars, one for each corner. Each linkage bar is provided with two wheels which are respectively mounted at the connections with the box press and the valve plate. The wheels are carried on the horizontal grooves formed in a door valve casing. In operation the shaft rotates and travels to permit the box press and the valve plate to move into the door valve casing while the valve plate does not contact the casing. When the box press reaches the home position, the wheels drop into the recesses which are disposed at the ends of the grooves, the valve plate is carried on the valve opening, and the box press presses the valve plate to increase the tightness. The valve plate does not suffer wear as it does not over other parts. (Yamaguchi, T.)

  19. Sequential transcatheter aortic valve implantation due to valve dislodgement

    DEFF Research Database (Denmark)

    Campante Teles, Rui; Costa, Cátia; Almeida, Manuel

    2017-01-01

    Transcatheter aortic valve implantation (TAVI) has become an important treatment in high surgical risk patients with severe aortic stenosis (AS), whose complications need to be managed promptly. The authors report the case of an 86-year-old woman presenting with severe symptomatic AS, rejected...

  20. Supra-annular valve strategy for an early degenerated transcatheter balloon-expandable heart valve.

    Science.gov (United States)

    Kamioka, Norihiko; Caughron, Hope; Corrigan, Frank; Block, Peter; Babaliaros, Vasilis

    2018-01-23

    Currently, there are no recommendations regarding the selection of valve type for a transcatheter heart valve (THV)-in-THV procedure. A supra-annular valve design may be superior in that it results in a larger effective orifice area and may have a lower chance of valve thrombosis after THV-in-THV. In this report, we describe the use of a supra-annular valve strategy for an early degenerated THV. © 2018 Wiley Periodicals, Inc.

  1. Aortic valve insufficiency in the teenager and young adult: the role of prosthetic valve replacement.

    Science.gov (United States)

    Bradley, Scott M

    2013-10-01

    The contents of this article were presented in the session "Aortic insufficiency in the teenager" at the congenital parallel symposium of the 2013 Society of Thoracic Surgeons (STS) annual meeting. The accompanying articles detail the approaches of aortic valve repair and the Ross procedure.(1,2) The current article focuses on prosthetic valve replacement. For many young patients requiring aortic valve surgery, either aortic valve repair or a Ross procedure provides a good option. The advantages include avoidance of anticoagulation and potential for growth. In other patients, a prosthetic valve is an appropriate alternative. This article discusses the current state of knowledge regarding mechanical and bioprosthetic valve prostheses and their specific advantages relative to valve repair or a Ross procedure. In current practice, young patients requiring aortic valve surgery frequently undergo valve replacement with a prosthetic valve. In STS adult cardiac database, among patients ≤30 years of age undergoing aortic valve surgery, 34% had placement of a mechanical valve, 51% had placement of a bioprosthetic valve, 9% had aortic valve repair, and 2% had a Ross procedure. In the STS congenital database, among patients 12 to 30 years of age undergoing aortic valve surgery, 21% had placement of a mechanical valve, 18% had placement of a bioprosthetic valve, 30% had aortic valve repair, and 24% had a Ross procedure. In the future, the balance among these options may be altered by design improvements in prosthetic valves, alternatives to warfarin, the development of new patch materials for valve repair, and techniques to avoid Ross autograft failure.

  2. Transitional nuclei near shell closures

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, G. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064 (India); Pai, H. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064, India and Present Address: Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstrasse 9, 64289 Darmstadt (Germany)

    2014-08-14

    High spin states in Bismuth and Thallium nuclei near the Z = 82 shell closure and Cesium nuclei near the N = 82 shell closure in A = 190 and A = 130 regions, respectively, have been experimentally investigated using heavy-ion fusion evaporation reaction and by detecting the gamma rays using the Indian National Gamma Array (INGA). Interesting shape properties in these transitional nuclei have been observed. The results were compared with the neighboring nuclei in these two regions. The total Routhian surface (TRS) calculations have been performed for a better understanding of the observed properties. In mass region A = 190, a change in shape from spherical to deformed has been observd around neutron number N = 112 for the Bi (Z = 83) isotopes with proton number above the magic gap Z = 82, whereas, the shape of Tl (Z = 81) isotopes with proton number below the magic gap Z = 82 remains stable as a function of neutron number. An important transition from aplanar to planar configuration of angular momentum vectors leading to the occurance of nuclar chirality and magnetic rotation, respectively, has been proposed for the unique parity πh{sub 11/2}⊗νh{sub 11/2} configuration in Cs isotopes in the mass region A ∼ 130 around neutron number N = 79. These results are in commensurate with the TRS calculations.

  3. Criticality assessment of LLRWDF closure

    International Nuclear Information System (INIS)

    Sarrack, A.G.; Weber, J.H.; Woody, N.D.

    1992-01-01

    During the operation of the Low Level Radioactive Waste Disposal Facility (LLRWDF), large amounts (greater than 100 kg) of enriched uranium (EU) were buried. This EU came primarily from the closing and decontamination of the Naval Fuels Facility in the time period from 1987--1989. Waste Management Operations (WMO) procedures were used to keep the EU boxes separated to prevent possible criticality during normal operation. Closure of the LLRWDF is currently being planned, and waste stabilization by Dynamic Compaction (DC) is proposed. Dynamic compaction will crush the containers in the LLRWDF and result in changes in their geometry. Research of the LLRWDF operations and record keeping practices have shown that the EU contents of trenches are known, but details of the arrangement of the contents cannot be proven. Reviews of the trench contents, combined with analysis of potential critical configurations, revealed that some portions of the LLRWDF can be expected to be free of criticality concerns while other sections have credible probabilities for the assembly of a critical mass, even in the uncompacted configuration. This will have an impact on the closure options and which trenches can be compacted

  4. Aorta measurements are heritable and influenced by bicuspid aortic valve

    Directory of Open Access Journals (Sweden)

    Lisa J Martin

    2011-09-01

    Full Text Available Abstract: Word Count 266, 1609 charactersObjectives: To determine whether the contributions of genetics and bicuspid aortic valve (BAV independently influence aortic (Ao dimensions.Background: Ao dilation is a risk factor for aneurysm, dissection, and sudden cardiac death. Frequent association of BAV with Ao dilation implicates a common underlying defect possibly due to genetic factors. Methods: Families enriched for BAV underwent standardized transthoracic echocardiography. In addition to BAV status, echocardiographic measures of Ao (annulus to descending Ao, pulmonary artery and mitral valve annulus diameters were obtained. Using variance components analysis, heritability was estimated with and without BAV status. Additionally, bivariate genetic analyses between Ao dimensions and BAV were performed.Results: Our cohort was obtained from 209 families enriched for BAV. After adjusting for age, body surface area and sex, individuals with BAV had a statistically significant increase in all echocardiographic measurements (p < 0.006 except descending Ao and mitral valve annulus. Individuals with BAV were at greater odds of having Ao dilation (OR = 4.44, 95% CI 2.93 – 6.72 than family members without BAV. All echocardiographic measurements exhibited moderate to strong heritability (0.25 to 0.53, and these estimates were not influenced by inclusion of BAV as a covariate. Bivariate genetic analyses supported that the genetic correlation between BAV and echo measures were not significantly different from zero.Conclusions: We show for the first time that echocardiographic measurements of Ao, pulmonary artery and mitral valve annulus diameters are quantitative traits that exhibit significant heritability. In addition, our results suggest the presence of BAV independently influences the proximal Ao and pulmonary artery measures but not those in the descending Ao or mitral valve annulus.

  5. Aortic valve function after bicuspidization of the unicuspid aortic valve.

    Science.gov (United States)

    Aicher, Diana; Bewarder, Moritz; Kindermann, Michael; Abdul-Khalique, Hashim; Schäfers, Hans-Joachim

    2013-05-01

    Unicuspid aortic valve (UAV) anatomy leads to dysfunction of the valve in young individuals. We introduced a reconstructive technique of bicuspidizing the UAV. Initially we copied the typical asymmetry of a normal bicuspid aortic valve (BAV) (I), later we created a symmetric BAV (II). This study compared the hemodynamic function of the two designs of a bicuspidized UAV. Aortic valve function was studied at rest and during exercise in 28 patients after repair of UAV (group I, n = 8; group II, n = 20). There were no differences among the groups I and II with respect to gender, age, body size, or weight. All patients were in New York Heart Association class I. Six healthy adults served as control individuals. All patients were studied with transthoracic echocardiography between 4 and 65 months postoperatively. Systolic gradients were assessed by continuous wave Doppler while patients were at rest and exercising on a bicycle ergometer. Aortic regurgitation was grade I or less in all patients. Resting gradients were significantly elevated in group I compared with group II and control individuals (group I, peak 33.8 ± 7.8 mm Hg; mean 19.1 ± 5.4 mm Hg; group II, peak 15.8 ± 5.4, mean 8.2 ± 2.8 mm Hg; control individuals, peak 6.0 ± 1.6, mean 3.2 ± 0.8 mm Hg; p competence. A symmetric repair design leads to improved systolic aortic valve function at rest and during exercise. Copyright © 2013 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  6. Motor-operated valve (MOV) actuator motor and gearbox testing

    International Nuclear Information System (INIS)

    DeWall, K.; Watkins, J.C.; Bramwell, D.

    1997-07-01

    Researchers at the Idaho National Engineering and Environmental Laboratory tested the performance of electric motors and actuator gearboxes typical of the equipment installed on motor-operated valves used in nuclear power plants. Using a test stand that simulates valve closure loads against flow and pressure, the authors tested five electric motors (four ac and one dc) and three gearboxes at conditions a motor might experience in a power plant, including such off-normal conditions as operation at high temperature and reduced voltage. They also monitored the efficiency of the actuator gearbox. All five motors operated at or above their rated starting torque during tests at normal voltages and temperatures. For all five motors, actual torque losses due to voltage degradation were greater than the losses calculated by methods typically used for predicting motor torque at degraded voltage conditions. For the dc motor the actual torque losses due to elevated operating temperatures were greater than the losses calculated by the typical predictive method. The actual efficiencies of the actuator gearboxes were generally lower than the running efficiencies published by the manufacturer and were generally nearer the published pull-out efficiencies. Operation of the gearbox at elevated temperature did not affect the operating efficiency

  7. Optothermally actuated capillary burst valve

    DEFF Research Database (Denmark)

    Eriksen, Johan; Bilenberg, Brian; Kristensen, Anders

    2017-01-01

    be burst by raising the temperature due to the temperature dependence of the fluid surface tension. We address individual valves by using a local heating platform based on a thin film of near infrared absorber dye embedded in the lid used to seal the microfluidic device [L. H. Thamdrup et al., Nano Lett...

  8. Spring valve for well completion

    Energy Technology Data Exchange (ETDEWEB)

    Gorbatov, P T

    1966-07-22

    A spring-loaded valve for well completion consists of a housing with a spring-loaded closing element. In order to protect the closing element from corrosion which might lower the pressure drop, the closing element is made in the form of a piston. It is tightly connected with sealing elements. The housing has orifices, overlapping the piston in the initial position.

  9. Hydraulic servo control spool valve

    Science.gov (United States)

    Miller, Donald M.

    1983-01-01

    A servo operated spool valve having a fixed sleeve and axially movable spool. The sleeve is machined in two halves to form a long, narrow tapered orifice slot across which a transverse wall of the spool is positioned. The axial position of the spool wall along the slot regulates the open orifice area with extreme precision.

  10. Statistical characteristics of mechanical heart valve cavitation in accelerated testing.

    Science.gov (United States)

    Wu, Changfu; Hwang, Ned H C; Lin, Yu-Kweng M

    2004-07-01

    Cavitation damage has been observed on mechanical heart valves (MHVs) undergoing accelerated testing. Cavitation itself can be modeled as a stochastic process, as it varies from beat to beat of the testing machine. This in-vitro study was undertaken to investigate the statistical characteristics of MHV cavitation. A 25-mm St. Jude Medical bileaflet MHV (SJM 25) was tested in an accelerated tester at various pulse rates, ranging from 300 to 1,000 bpm, with stepwise increments of 100 bpm. A miniature pressure transducer was placed near a leaflet tip on the inflow side of the valve, to monitor regional transient pressure fluctuations at instants of valve closure. The pressure trace associated with each beat was passed through a 70 kHz high-pass digital filter to extract the high-frequency oscillation (HFO) components resulting from the collapse of cavitation bubbles. Three intensity-related measures were calculated for each HFO burst: its time span; its local root-mean-square (LRMS) value; and the area enveloped by the absolute value of the HFO pressure trace and the time axis, referred to as cavitation impulse. These were treated as stochastic processes, of which the first-order probability density functions (PDFs) were estimated for each test rate. Both the LRMS value and cavitation impulse were log-normal distributed, and the time span was normal distributed. These distribution laws were consistent at different test rates. The present investigation was directed at understanding MHV cavitation as a stochastic process. The results provide a basis for establishing further the statistical relationship between cavitation intensity and time-evolving cavitation damage on MHV surfaces. These data are required to assess and compare the performance of MHVs of different designs.

  11. Guidelines for valves in tritium service

    International Nuclear Information System (INIS)

    Weaver, W.W.

    1994-01-01

    Some undesirable practices and misapplications that caused valve-related failures are examined, and future courses of action are recommended to avoid repetition of these events. Desirable valve characteristics and practices that should be considered when selecting valves for use in tritium service are also discussed. Supporting logic for the desirability of these features is presented by discussing the mechanisms of valve degradation followed by examples of related events. Desirable valve and system features and operational actions are grouped into two categories: strongly recommended and recommended. 13 refs., 1 fig

  12. Valve assembly having remotely replaceable bearings

    International Nuclear Information System (INIS)

    Johnson, E.R.; Tanner, D.E.

    1980-01-01

    A valve assembly having remotely replaceable bearings is disclosed wherein a valve disc is supported within a flow duct for rotation about a pair of axially aligned bearings, one of which is carried by a spindle received within a diametral bore in the valve disc, and the other of which is carried by a bearing support block releasably mounted on the duct circumferentially of an annular collar on the valve disc coaxial with its diametrical bore. The spindle and bearing support block are adapted for remote removal to facilitate servicing or replacement of the valve disc support bearings

  13. Multifunctional four-port directional control valve constructed from logic valves

    International Nuclear Information System (INIS)

    Lisowski, E.; Czyżycki, W.; Rajda, J.

    2014-01-01

    Highlights: • Directional valve with standard ISO 440-08 has been constructed from logic valves. • Only one innovative valve may replace whole family of the standard valves. • CFD analysis and bench tests of the innovative valve has been carried. • Parameters of the innovative valve are equaling or surpassing the standard ones. • The innovative valve has additional possibilities of pressure and flow control. - Abstract: The paper refers to four-port solenoid pilot operated valves, which are subplate mounted in a hydraulic system in accordance with the ISO 4401 standard. Their widespread use in many machines and devices causes a continuing interest in the development of their design by both the scientific centers and the industry. This paper presents an innovative directional control valve based on the use of logic valves and a methodology followed for the design of it by using Solid Edge CAD and ANSYS/Fluent CFD software. The valve design methodology takes into account the need to seek solutions that minimize flow resistance through the valve. For this purpose, the flow paths are prepared by means of CAD software and pressure-flow curves are determined as a result of CFD analysis. The obtained curves are compared with the curves available in the catalogs of spool type directional control valves. The new solution allows to replace the whole family of spool type four-port directional control valves by one valve built of logic valves. In addition, the innovative directional control valve provides leak-proof shutting the flow paths off and also it can control flow rate and even pressure of working liquid. A prototype of the valve designed by the presented method has been made and tested on the test bench. The results quoted in the paper confirm that the developed logic type directional control valve is able to meet all designed connection configurations, and the obtained pressure-flow curves show very good conformity with the results of CFD analysis

  14. Hospital closure: Phoenix, Hydra or Titanic?

    Science.gov (United States)

    Dunne, T; Davis, S

    1996-01-01

    Very little has been published about the effects of hospital closure in terms of the service, financial or management issues of the process. Attempts through a case-study format to redress the balance and as such represents the reflections of practitioners who have recently undergone the experience of hospital closure and the often neglected issues arising both during and after the process.

  15. Key financial ratios can foretell hospital closures.

    Science.gov (United States)

    Lynn, M L; Wertheim, P

    1993-11-01

    An analysis of various financial ratios sampled from open and closed hospitals shows that certain leverage, liquidity, capital efficiency, and resource availability ratios can predict hospital closure up to two years in advance of the closure with an accuracy of nearly 75 percent.

  16. 40 CFR 264.178 - Closure.

    Science.gov (United States)

    2010-07-01

    ... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS FOR OWNERS AND OPERATORS OF HAZARDOUS WASTE TREATMENT, STORAGE, AND DISPOSAL FACILITIES Use and Management of Containers § 264.178 Closure. At closure, all hazardous waste and hazardous waste residues must be removed...

  17. Hanford Patrol Academy Demolition Sites Closure Plan

    International Nuclear Information System (INIS)

    1992-11-01

    From 1975 to 1991 the Hanford Patrol Academy Demolition Sites (HPADS) were used for demolition events. These demolition events were a form of thermal treatment for spent or abandoned chemical waste. Because the HPADS will no longer be used for this thermal activity, the sites will be closed. Closure will be conducted pursuant to the requirements of the Washington State Department of Ecology (Ecology) Dangerous Waste Regulations, Washington Administrative Code (WAC) 173-303-610 and 40 CFR 270.1. Closure also will satisfy closure requirements of WAC 173-303-680 and for the thermal treatment closure requirements of 40 CFR 265.381. This closure plan presents a description of the HPADS, the history of the waste treated, and the approach that will be followed to close the HPADS. Because dangerous waste does not include the source, special nuclear, and by-product material components of mixed waste, radionuclides are not within the scope of WAC 173-303 or of this closure plan. The information on radionuclides is provided only for general knowledge where appropriate. Only dangerous constituents derived from HPADS operations will be addressed in this closure plan in accordance with WAC 173-303-610(2)(b)(i). The HPADS are actually two distinct soil closure areas within the Hanford Patrol Academy training area

  18. Analysis of Water Hammer with Different Closing Valve Laws on Transient Flow of Hydrogen-Natural Gas Mixture

    Directory of Open Access Journals (Sweden)

    Norazlina Subani

    2015-01-01

    Full Text Available Water hammer on transient flow of hydrogen-natural gas mixture in a horizontal pipeline is analysed to determine the relationship between pressure waves and different modes of closing and opening of valves. Four types of laws applicable to closing valve, namely, instantaneous, linear, concave, and convex laws, are considered. These closure laws describe the speed variation of the hydrogen-natural gas mixture as the valve is closing. The numerical solution is obtained using the reduced order modelling technique. The results show that changes in the pressure wave profile and amplitude depend on the type of closing laws, valve closure times, and the number of polygonal segments in the closing function. The pressure wave profile varies from square to triangular and trapezoidal shape depending on the type of closing laws, while the amplitude of pressure waves reduces as the closing time is reduced and the numbers of polygonal segments are increased. The instantaneous and convex closing laws give rise to minimum and maximum pressure, respectively.

  19. [Tricuspid valve insufficiency: what should be done?].

    Science.gov (United States)

    von Segesser, L K; Stauffer, J C; Delabays, A; Chassot, P G

    1998-12-01

    Tricuspid regurgitation is relatively common. Due to the progress made in echocardiography, its diagnosis is in general made readily and in reliable fashion. Basically one has to distinguish between functional tricuspid valve regurgitation due to volume and/or pressure overload of the right ventricle with intact valve structures versus tricuspid valve regurgitation due to pathologic valve structures. The clear identification of the regurgitation mechanism is of prime importance for the treatment. Functional tricuspid valve regurgitation can often be improved by medical treatment of heart failure, and eventually a tricuspid valve plasty can solve the problem. However, the presence of pathologic tricuspid valve structures makes in general more specific plastic surgical procedures and even prosthetic valve replacements necessary. A typical example for a structural tricuspid valve regurgitation is the case of a traumatic papillary muscle rupture. Due to the sudden onset, this pathology is not well tolerated and requires in general surgical reinsertion of the papillary muscle. In contrast, tricuspid valve regurgitation resulting from chronic pulmonary embolism with pulmonary artery hypertension, can be improved by pulmonary artery thrombendarteriectomy and even completely cured with an additional tricuspid annuloplasty. However, tricuspid regurgitations due to terminal heart failure are not be addressed with surgery directed to tricuspid valve repair or replacement. Heart transplantation, dynamic cardiomyoplasty or mechanical circulatory support should be evaluated instead.

  20. Valve for closing a steam line

    International Nuclear Information System (INIS)

    Meyer, W.; Potrykus, G.

    1976-01-01

    Instead of several control elements, the quick-closing valve, especially in the main-steam line between steam generator and turbine of a power station has the valve cone itself as the only movable part, acting with its inner surface as a piston within a second cylinder space. The valve shaft is at the same time a piston rod with a stepped piston at the upper end. This piston is loaded in a cylinder at the upspace below the valve cover on one hand by a spring, on the other hand by its own medium. Two non-return valves, one of it in a bore of the valve cone, connect the first-mentioned cylinder space with the steam-loaded inlet resp. outlet side of the valve. For controlling the valve, a magnet valve is sufficient. By automatic control of the valve cone coupled with several pistons several control lines can be omitted. There are also no pressurized control lines outside the valve which could be damaged by exterior influences. (ERA) [de

  1. Mechanical versus bioprosthetic aortic valve replacement.

    Science.gov (United States)

    Head, Stuart J; Çelik, Mevlüt; Kappetein, A Pieter

    2017-07-21

    Mechanical valves used for aortic valve replacement (AVR) continue to be associated with bleeding risks because of anticoagulation therapy, while bioprosthetic valves are at risk of structural valve deterioration requiring reoperation. This risk/benefit ratio of mechanical and bioprosthetic valves has led American and European guidelines on valvular heart disease to be consistent in recommending the use of mechanical prostheses in patients younger than 60 years of age. Despite these recommendations, the use of bioprosthetic valves has significantly increased over the last decades in all age groups. A systematic review of manuscripts applying propensity-matching or multivariable analysis to compare the usage of mechanical vs. bioprosthetic valves found either similar outcomes between the two types of valves or favourable outcomes with mechanical prostheses, particularly in younger patients. The risk/benefit ratio and choice of valves will be impacted by developments in valve designs, anticoagulation therapy, reducing the required international normalized ratio, and transcatheter and minimally invasive procedures. However, there is currently no evidence to support lowering the age threshold for implanting a bioprosthesis. Physicians in the Heart Team and patients should be cautious in pursuing more bioprosthetic valve use until its benefit is clearly proven in middle-aged patients. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2017. For permissions, please email: journals.permissions@oup.com.

  2. Acoustic valve leak detection in nuclear plants

    International Nuclear Information System (INIS)

    Dimmick, J.G.; Dickey, J.W.

    1983-01-01

    Internal valve leakage is a hidden energy loss and can cause or prolong a forced outage. Recent advances in acoustic detection of internal valve leakage have reduced piping system maintenance costs, unnecessary downtime, and energy waste. Extremely short payback periods have been reported by plants applying this technology to preventive maintenance, troubleshooting, energy conservation and outage planning. Sensors temporarily attached to the outside of valves and connected to the instruments detect ultrasonic acoustic emissions which are characteristic of internal valve leakage. Since the sensors are attached to the outside of the valves, the time and expense of dismantling the valves or removing them from the systems are eliminated. This paper describes the instrumentation and specific applications to nuclear plant valves, including independent verification of initial findings. Guidelines for potential users, including instrumentation selection, training requirements, application planning, and the choice of in-house versus contract services are discussed

  3. Some Recent Developments in Turbulence Closure Modeling

    Science.gov (United States)

    Durbin, Paul A.

    2018-01-01

    Turbulence closure models are central to a good deal of applied computational fluid dynamical analysis. Closure modeling endures as a productive area of research. This review covers recent developments in elliptic relaxation and elliptic blending models, unified rotation and curvature corrections, transition prediction, hybrid simulation, and data-driven methods. The focus is on closure models in which transport equations are solved for scalar variables, such as the turbulent kinetic energy, a timescale, or a measure of anisotropy. Algebraic constitutive representations are reviewed for their role in relating scalar closures to the Reynolds stress tensor. Seamless and nonzonal methods, which invoke a single closure model, are reviewed, especially detached eddy simulation (DES) and adaptive DES. Other topics surveyed include data-driven modeling and intermittency and laminar fluctuation models for transition prediction. The review concludes with an outlook.

  4. Pit closures - effects and alternatives

    Energy Technology Data Exchange (ETDEWEB)

    Stott, A G

    1987-02-01

    During the last decade, British Coal has closed around 100 mines. This article illustrates the effect of pit closures on the colliery's workforce, and the local community and its economy. Working conditions at Newmarket Colliery and the Selby coalfield are compared within the context of British Coal's national transfer market. British Coal's transfer benefits include resettlement payments and mortgage subsidies. The job creation venture of British Coal Enterprise Ltd. has helped to create over 3700 new jobs in 264 projects, involving a total investment of 38 M pounds sterling. The article also discusses deputies' qualifications and prospects for recently qualified management staff, and gives a comparison of losses suffered by the different mining unions.

  5. Closure of Microcosm for refurbishment

    CERN Multimedia

    2014-01-01

    Since 1994, the Microcosm exhibition has given the opportunity to visitors of all ages and backgrounds to have a first glimpse into the secrets of physics.   To ensure that Microcosm can continue fulfilling its educational aims at the same level of quality for many years to come, it is closing for renovation work on 8 December 2014 and is expected to reopen during Summer 2015. During the closure, the “Fun with Physics” workshop will not take place, but the Universe of Particles exhibition in the Globe and the Passport to the Big Bang circuit will remain accessible to the public, free of charge and with no need to book in advance.  Guided tours of CERN are also available (advance booking required via this page).

  6. Transcatheter aortic valve prosthesis surgically replaced 4 months after implantation

    DEFF Research Database (Denmark)

    Thyregod, Hans Gustav; Lund, Jens Teglgaard; Engstrøm, Thomas

    2010-01-01

    Transcatheter aortic valve implantation is a new and rapidly evolving treatment option for high-risk surgical patients with degenerative aortic valve stenosis. Long-term results with these new valve prostheses are lacking, and potential valve dysfunction and failure would require valve replacemen....... We report the first case of surgical valve replacement in a patient with a dysfunctional transcatheter-implanted aortic valve prosthesis 4 months after implantation....

  7. PATs Operating in Water Networks under Unsteady Flow Conditions: Control Valve Manoeuvre and Overspeed Effect

    Directory of Open Access Journals (Sweden)

    Modesto Pérez-Sánchez

    2018-04-01

    Full Text Available The knowledge of transient conditions in water pressurized networks equipped with pump as turbines (PATs is of the utmost importance and necessary for the design and correct implementation of these new renewable solutions. This research characterizes the water hammer phenomenon in the design of PAT systems, emphasizing the transient events that can occur during a normal operation. This is based on project concerns towards a stable and efficient operation associated with the normal dynamic behaviour of flow control valve closure or by the induced overspeed effect. Basic concepts of mathematical modelling, characterization of control valve behaviour, damping effects in the wave propagation and runaway conditions of PATs are currently related to an inadequate design. The precise evaluation of basic operating rules depends upon the system and component type, as well as the required safety level during each operation.

  8. The Ahmed Glaucoma Valve in Refractory Glaucoma: Experiences in Southwest Ethiopia.

    Science.gov (United States)

    Gessesse, Girum W

    2015-07-01

    The management of refractory glaucoma is a challenging task for any glaucoma surgeon. This study is aimed to evaluate the efficacy of Ahmed Glaucoma Valve implantation in refractory glaucomas in South-West Ethiopia. A retrospective review was conducted on the charts of consecutive patients treated with Ahmed glaucoma valve implantation at Jimma University Specialized Hospital between August 2012 and August 2014. Success was defined as Intraocular Pressure (IOP) less than 22 mm Hg and greater than 5mm Hg at 6 months, with at least 30% reduction from baseline, without medical therapy (complete success) or either with or without medication (qualified successes). A total of 12 eyes of 11 patients were included. The mean age of patients was 40.7 (SD= 19.0) years; 63.6% of them were males. The main types of glaucoma were pseudoexfoliative (3 eyes), uveitic (2 eyes), chronic angle closure (2 eyes) and Juvenile Open Angle (JOAG) (2 eyes). The mean IOP was reduced from preoperative level (32.75±7.14 mmHg) to (15.75 ±4.35 mmHg) at six postoperative months, (PAhmed glaucoma valve implant appears to be effective and relatively safe for treating complicated glaucomas with success rate comparable with those reported from other studies. Ahmed glaucoma valve, refractory glaucoma, complications, Ethiopia.

  9. Operating experience of main steam isolation valves at Fessenheim and Bugey

    International Nuclear Information System (INIS)

    Dredemis, G.; Fourest, B.; Giroux, C.

    1985-07-01

    The paper presents the experience of Hopkinson MSIVs over about 40 reactor-years (1977 to 1984) of operation at Fessenheim and Bugey units (900 MWe PWR). The various problems encountered including ageing effects on auxiliary equipments and increases in closure time are discussed. The corrective actions undertaken by the utility and the safety assessment of these events performed by the french safety authorities are also described. This study is the synthesis of an in-depth analysis of Main Steam Isolation Valves (MSIV) and their auxiliary circuits equipping the Bugey and Fessenheim 900 MWe PWR nuclear power plants. These valves are different from those installed in the other French 900 MWe PWR reactors. The evaluation of the operation of these valves was made on the basis of incidents which occured during operation of the units or during the periodic tests, as well as anomalies discovered during maintenance operations. This analysis proved that the anomalies related to the design of the valves, as well as to their manufacture and installation, had been correctly dealt with. Furthermore, it should have also revealed potential anomalies due to ageing of the equipment

  10. Application of ceramics to the sliding seat of valve bridge; Valve bridge yodobu eno ceramics tekiyo

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, T; Ono, T [Mitsubishi Motors Corp., Tokyo (Japan)

    1997-10-01

    For use in the valve train, using an OHV (over head valve) configuration. of a 4 valve diesel engine for trucks and buses; we developed a valve bridge, a component of a valve train, with a ceramic head that is made of silicon nitride(Si3N4) in contact with a rocker arm in order to reduce cost and improve wear resistance for further diesel engine emissions regulations. In order to evaluate the effect of this valve bridge, RIG tests and durability tests on actual engines were carried out. 7 figs., 2 tabs.

  11. Aortic valve-sparing in 37 patients with Marfan syndrome: midterm results with David operation.

    Science.gov (United States)

    Forteza, Alberto; De Diego, Javier; Centeno, Jorge; López, Maria Jesus; Pérez, Enrique; Martín, Carlos; Sánchez, Violeta; Rufilanchas, Juan J; Cortina, Jose

    2010-01-01

    We reviewed our experience with aortic valve-sparing operations in Marfan syndrome during last 5 years. Between March 2004 and June 2009, 94 patients with aortic root aneurysms underwent valve-sparing operations. Of these, 37 (68% male) were diagnosed with Marfan syndrome, according to the Ghent diagnostic criteria. Mean age was 30 +/- 10 years (range, 11 to 59 years). Moderate/severe aortic regurgitation was present in 13%, and the mean diameter of the Valsalva sinuses was 50 +/- 4 mm (range, 42 to 62 mm). The David V modification was performed in the last 28 patients. Additional procedures were mitral valve repair in 6, tricuspid valve repair in 3, closure of septal atrial defect in 2, and closure of a patent foramen ovale in 13. Mean follow-up was 27 +/- 16 months (range, 1 to 61 months). There were no in-hospital deaths and no major adverse outcomes. One patient required implantation of a mechanical prosthesis during the same procedure because of moderate aortic regurgitation. One late death occurred. No patients required reoperation. In the last follow-up, 23 patients did not have aortic regurgitation, 12 had grade I, and 1 had grade II. No thromboembolic complications have been documented, and 97% of the patients are free from anticoagulation. Short-term and midterm results with the reimplantation technique for aortic root aneurysms in Marfan patients are excellent. If long-term results are similar, this technique could be the treatment of choice for these patients. 2010 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  12. Analysis of the RBMK-1500 type reactor emergency core cooling system behavior, taking into account the specified hydraulic characteristics of fast acting motor valves

    International Nuclear Information System (INIS)

    Kaliatka, A.; Ognerubov, V.; Adomavicius, A.; Ziedelis, S.

    2005-01-01

    During the accident analysis of nuclear power plants, reliability and uncertainty of results depends on adequateness of mathematical models of main elements and phenomena in systems important to safety. The best way for qualification of these models is collation with relevant experimental data. However, at the case of lack of such data modern computational fluid dynamics codes can be used for this purpose. This paper presents the results of an attempt to specify the hydraulic characteristics of the fast acting motor valves as well as to demonstrate the impact of these characteristics to transient processes in emergency core cooling system of the RBMK-1500 type reactor. For these purposes the finite element model of fast acting motor valve was developed and analyzed, using two separate computational fluid dynamics codes in parallel: CFX5 and COSMOS/FLOWORKS. Both all main design particularities and changes of flow structure during valve opening (closure) process were taken into account. It was demonstrated, that the obtained dependencies of changes of hydraulic loss coefficient in respect of relative valve opening (closure) rate substantially differ from those commonly used in thermal-hydraulic calculations of nuclear reactors. This difference is extremely big at the square one of the valve opening process, when the value of the valve hydraulic resistance is most important to flow of coolant channelized to the group distribution header. The series of thermal-hydraulic calculations of the maximum design-basis accident initiated by full break of main circulation pump pressure header were performed. The obtained dependencies of changes of hydraulic loss coefficient in respect of relative valve opening (closure) rate as well as those commonly used in thermal-hydraulic code RELAP5 were used. The results of calculations show, that in the initial stage of accident flow of coolant going from emergency core cooling system via fast acting motor valves to group distribution

  13. Performance of balanced bellows safety relief valves

    International Nuclear Information System (INIS)

    Lai, Y.S.

    1992-01-01

    By the nature of its design, the set point and lift of a conventional spring loaded safety relief valve are sensitive to back pressure. One way to reduce the adverse effects of the back pressure on the safety relief valve function is to install a balanced bellows in a safety relief valve. The metallic bellows has a rather wide range of manufacturing tolerance which makes the design of the bellows safety relief valve very complicated. The state-of-the-art balanced bellows safety relief valve can only substantially minimize, but cannot totally eliminate the back pressure effects on its set point and relieving capacity. Set point change is a linear function of the back pressure to the set pressure ratio. Depending on the valve design, the set point correction factor can be either greater or smaller than unity. There exists an allowable back pressure and critical back pressure for each safety relief valve. When total back pressure exceeds the R a , the relieving capacity will be reduced mainly resulting from the valve lift being reduced by the back pressure and the capacity reduction factor should be applied in valve sizing. Once the R c is exceeded, the safety relief valve becomes unstable and loses its over pressure protection capability. The capacity reduction factor is a function of system overpressure, but their relationship is non-linear in nature. (orig.)

  14. Simple Check Valves for Microfluidic Devices

    Science.gov (United States)

    Willis, Peter A.; Greer, Harold F.; Smith, J. Anthony

    2010-01-01

    A simple design concept for check valves has been adopted for microfluidic devices that consist mostly of (1) deformable fluorocarbon polymer membranes sandwiched between (2) borosilicate float glass wafers into which channels, valve seats, and holes have been etched. The first microfluidic devices in which these check valves are intended to be used are micro-capillary electrophoresis (microCE) devices undergoing development for use on Mars in detecting compounds indicative of life. In this application, it will be necessary to store some liquid samples in reservoirs in the devices for subsequent laboratory analysis, and check valves are needed to prevent cross-contamination of the samples. The simple check-valve design concept is also applicable to other microfluidic devices and to fluidic devices in general. These check valves are simplified microscopic versions of conventional rubber- flap check valves that are parts of numerous industrial and consumer products. These check valves are fabricated, not as separate components, but as integral parts of microfluidic devices. A check valve according to this concept consists of suitably shaped portions of a deformable membrane and the two glass wafers between which the membrane is sandwiched (see figure). The valve flap is formed by making an approximately semicircular cut in the membrane. The flap is centered over a hole in the lower glass wafer, through which hole the liquid in question is intended to flow upward into a wider hole, channel, or reservoir in the upper glass wafer. The radius of the cut exceeds the radius of the hole by an amount large enough to prevent settling of the flap into the hole. As in a conventional rubber-flap check valve, back pressure in the liquid pushes the flap against the valve seat (in this case, the valve seat is the adjacent surface of the lower glass wafer), thereby forming a seal that prevents backflow.

  15. Quantitative assessment of an aortic and pulmonary valve function according to valve fenestration

    International Nuclear Information System (INIS)

    Mirkhani, S.H.; Golestani, M.G.; Hosini, M.; Kazemian, A.

    1999-01-01

    There are some reasons for malfunction of aortic and pulmonary valve like fibrosis, calcification, and atheroma. Although, in some papers fenestration were known as a pathologic sign, but it is not generally accepted, while this matter is important in choosing suitable Homograft Heart Valve. In this paper fenestrations and its size, numbers and situation effect was studied. We collected 98 hearts, the donors died because of accident, we excluded valves with atheroma, calcification, fibrosis and unequal cusps, 91 aortic and 93 pulmonary valves were given further consideration. We classified valves according to situation, number and size of fenestration. Each valve was tested with 104 cm of non-nal saline column pressure which is equal to 76 mm Hg. Valve efficacy was detected by fluid flow assay. With study of 184 valves, 95 had no fenestration, 64 had less than 2 fenestration and 25 had more than 2 fenestration. Valve efficacy in condition of less than 2 fenestration was more than others (p <0.01). Malfunction effects of fenestration increased in larger valve and it will be decreased if their situation would be marginal (free margin of cusp). In the comparison of aortic and pulmonary valve we saw that malfunction effect of fenestration in pulmonary valve was more than aortic valve. Our experience in Immam Khomeini Homograft Valve Bank has shown that a great deal of valves is fenestrated. It seems that fenestration must be considered as a quality criterion in homograft valve preparation, especially in pulmonary and large aortic valves; but complementary studies is necessary

  16. Organic evaporator steam valve failure

    International Nuclear Information System (INIS)

    Jacobs, R.A.

    1992-01-01

    Defense Waste Processing Facility (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. Aerococcus viridans Native Valve Endocarditis

    Directory of Open Access Journals (Sweden)

    Wenwan Zhou

    2013-01-01

    Full Text Available Aerococcus viridans is an infrequent human pathogen and few cases of infective endocarditis have been reported. A case involving a 69-year-old man with colon cancer and hemicolectomy 14 years previously, without recurrence, is reported. A diagnosis of native mitral valve endocarditis was established on the basis of clinical presentation, characteristic echocardiographic findings and pathological specimen examination after urgent valve replacement. A viridans endocarditis appears to be particularly virulent, requiring a surgical approach in four of 10 cases reported and death in one of nine. Given the aggressive nature of A viridans endocarditis and the variable time to diagnosis (a few days to seven months, prompt recognition of symptoms and echocardiography, in addition to blood cultures, should be performed when symptoms persist.

  18. Bistable diverter valve in microfluidics

    Czech Academy of Sciences Publication Activity Database

    Tesař, Václav; Bandulasena, H.C.H.

    2011-01-01

    Roč. 50, č. 5 (2011), s. 1225-1233 ISSN 0723-4864 R&D Projects: GA ČR GA101/07/1499; GA AV ČR IAA200760705 Institutional research plan: CEZ:AV0Z20760514 Keywords : fluidics * bistable diverter valves * pressure-driven microfluidics Subject RIV: BK - Fluid Dynamics Impact factor: 1.735, year: 2011 http://www.springerlink.com/content/x4907p1908151522/

  19. Social and macro economic impact of closure

    International Nuclear Information System (INIS)

    Medeliene, D.

    1999-01-01

    The social consequences of closure of Ignalina NPP will largely depend on the actions the Government takes. If it puts in place the conditions which enable the International Financial Institutions to assist Lithuania, both in providing loans and grants for decommissioning and (in the case of the EU) providing Structural Adjustment Funds for the regional economic development of the Visaginas area, then solutions to the problems of closure can be found. But if the Government delays putting into place the necessary conditions, then Lithuania will be left to solve the problems of - inter alia necessary - closure of Ignalina NPP on its own. (author)

  20. Control valve friction operational experience at Darlington NGD

    International Nuclear Information System (INIS)

    Speer, B.

    1995-01-01

    Proper installation of valve packing is an important part of ensuring that control valves operate as intended. Darlington NGD has developed a Valve Packing Program. This program combined with valve diagnostics has enabled the station to ensure that the operability of control valves is maintained after repacking. This paper outlines the process that is used for this. (author)

  1. Transcatheter aortic valve prosthesis surgically replaced 4 months after implantation

    DEFF Research Database (Denmark)

    Thyregod, Hans Gustav; Lund, Jens Teglgaard; Engstrøm, Thomas

    2010-01-01

    Transcatheter aortic valve implantation is a new and rapidly evolving treatment option for high-risk surgical patients with degenerative aortic valve stenosis. Long-term results with these new valve prostheses are lacking, and potential valve dysfunction and failure would require valve replacemen...

  2. Pivot design in bileaflet valves.

    Science.gov (United States)

    Vallana, F; Rinaldi, S; Galletti, P M; Nguyen, A; Piwnica, A

    1992-01-01

    The design criteria leading to the development of a new bileaflet valve (Sorin Bicarbon) were derived from the analysis of functional requirements, the performance of existing prostheses, and the availability of an advanced carbon coating technology (Carbofilm). The hinge is the critical element affecting fluid dynamics, durability, and thrombus formation in bileaflet valves. A comparative study of three existing models led to a new hinge design that was based on coupling two spheric surfaces with different radii of curvature (leaflet pivot and hinge recess) and obtained by electroerosion into a Carbofilm-coated metallic housing. In this valve, the point of contact moves continuously by rolling, not sliding. This minimizes friction and wear and allows uninterrupted washing of the blood exposed surfaces even during diastole (a finding established in patients using transesophageal echocardiography). Tricuspid implantation without anticoagulation in 33 sheep did not lead to thrombotic events (follow-up, 40-400 days). In the first 36 clinical implants observed for 15 months (mitral position, size 29; two unrelated deaths), the mean diastolic gradient by echo Doppler was 4 +/- 1.25 mmHg; the functional area was 3.2 +/- 0.6 cm2. No leaflet fracture and no thrombotic or embolic complications were observed clinically using a standard anticoagulant regimen.

  3. An Absolute Valve for the ITER Neutral Beam Injector

    International Nuclear Information System (INIS)

    Jones, Ch.; Chuilon, B.; Michael, W.

    2006-01-01

    In the ITER reference design a fast shutter was included to limit tritium migration into the beamline vacuum enclosures. The need was recently identified to extend the functionality of the fast shutter to that of an absolute valve in order to facilitate injector maintenance procedures and to satisfy safety requirements in case of an in-vessel loss of coolant event. Three concepts have been examined satisfying the ITER requirements for speed of actuation, sealing performance over the required lifetime, and pressure differential in fault scenarios, namely: a rectangular closure section; a circular cross section; and a rotary JET-type valve. The rectangular section represents the most efficient usage of the available space envelope and leads to a minimum-mass system, although it requires greater total force for a given load per unit length of seal. However, a metallic seal of the '' hard/hard '' type, where the seal relies on the elastic properties of the material and does not utilise any type of spring device, can provide the required seal performance with typical loading of 200 kg/cm. The conceptual design of the proposed absolute valve will be presented. The aperture dimensions are 1.45 m high by 0.6 m wide, with minimum achievable leak rate of 1 · 10 -9 mbarl/s and maximum pressure differential of 3 bar across the valve. Sealing force is provided using two seal plates, linked by a 3 mm thick ' omega ' diaphragm, by pressurisation of the interspace to 8 bar; this allows for a relative movement of the plates of 2 mm. Movement of the device perpendicular to the beam direction is carried out using a novel magnetic drive in order to transmit the motive force across the vacuum boundary, similar to that demonstrated on a test-rig in an earlier study. The conceptual design includes provision of all the services such as pneumatics and water cooling to cope with the heat loads from neutral beams in quasi steady-state operation and from the ITER plasma. A future programme

  4. Design and performance characteristic analysis of servo valve-type water hydraulic poppet valve

    International Nuclear Information System (INIS)

    Park, Sung Hwan

    2009-01-01

    For water hydraulic system control, the flow or pressure control using high-speed solenoid valve controlled by PWM control method could be a good solution for prevention of internal leakage. However, since the PWM control of on-off valves cause extensive flow and pressure fluctuation, it is difficult to control the water hydraulic actuators precisely. In this study, the servo valve-type water hydraulic valve using proportional poppet as the main valve is designed and the performance characteristics of the servo valve-type water hydraulic valve are analyzed. Furthermore, it is demonstrated through experiments that a decline in control chamber pressure that follows the change of pilot flow is caused by the occurrence of cavitation around the proportional poppet, and that fundamental characteristics of the developed valve remain unaffected by the occurrence of cavitation

  5. Quantification of operator actions during ATWS following MSIV closure

    International Nuclear Information System (INIS)

    Luckas, W.J. Jr.; O'Brien, J.N.; Perline, R.K.; Spettell, C.M.

    1986-01-01

    Brookhaven National Laboratory (BNL) assisted the Accident Sequence Evaluation Program (ASEP) by performing a Human Reliability Analysis (HRA) of the operations crew tasks during the Anticipated Transient Without Scram (ATWS) accident sequence with Main Steam Isolation Valve (MSIV) closure at the Peach Bottom Atomic Power Station, Unit 2. A detailed task analysis was performed based on consideration of staffing, team interaction, and control room layout at Peach Bottom. ATWS scenarios developed by Oak Ridge National Laboratory (ORNL) and Idaho National Engineering Laboratory (INEL) were reviewed. Discussions were held with thermal-hydrodynamic/core neutronics engineers at BNL to determine the success criterion for tasks. Five major operator tasks were identified. After reviewing a computerized data base of human error probabilities (HEPs) from 19 probabilistic risk assessments (PRAs) for tasks similar to those above to establish the historic range of HEPs for such errors, consensus opinion and structured expert judgment was used to quantify each of these tasks at each branch point in the event tree within that range

  6. 3D Printed Multimaterial Microfluidic Valve.

    Directory of Open Access Journals (Sweden)

    Steven J Keating

    Full Text Available We present a novel 3D printed multimaterial microfluidic proportional valve. The microfluidic valve is a fundamental primitive that enables the development of programmable, automated devices for controlling fluids in a precise manner. We discuss valve characterization results, as well as exploratory design variations in channel width, membrane thickness, and membrane stiffness. Compared to previous single material 3D printed valves that are stiff, these printed valves constrain fluidic deformation spatially, through combinations of stiff and flexible materials, to enable intricate geometries in an actuated, functionally graded device. Research presented marks a shift towards 3D printing multi-property programmable fluidic devices in a single step, in which integrated multimaterial valves can be used to control complex fluidic reactions for a variety of applications, including DNA assembly and analysis, continuous sampling and sensing, and soft robotics.

  7. The radiology of prosthetic heart valves

    International Nuclear Information System (INIS)

    Steiner, R.M.; Flicker, S.

    1985-01-01

    The development of prosthetic heart valves in the late 1950s ushered in a new era in the treatment of heart disease. The radiologist has an important role to play preoperatively in the diagnosis of valvular heart disease. Radiology is valuable in identification of the implanted prosthetic valve and recognition of complications associated with valve implantation. Radiologists must be familiar with the imaging techniques best suited to evaluate the function of the valve prosthesis in question. In this chapter the authors discuss the radiographic approach to the evaluation of the status of patients for valve replacement and the imaging problems peculiar to the types of valves in current use. The relative value of plain-film radiography, fluoroscopy, videorecording and cinerecording, and aortography is addressed, as well as the potential value of magnetic resonance imaging and subsecond dynamic computed tomography

  8. Trans-apical aortic valve implantation in a patient with stentless valve degeneration.

    Science.gov (United States)

    Kapetanakis, Emmanouil I; MacCarthy, Philip; Monaghan, Mark; Wendler, Olaf

    2011-06-01

    Trans-apical valve-in-valve trans-catheter aortic valve implantation (TAVI) has successfully been performed in selected, high-risk patients, who suffered prosthetic degeneration after aortic valve replacement using stented xenografts. We report the case of a 79-year-old male patient who underwent one of the first successful TAVIs in a failing stentless bioprosthesis. Copyright © 2010 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.

  9. Optimal valve location in long oil pipelines

    OpenAIRE

    Grigoriev, A.; Grigorieva, N.V.

    2007-01-01

    We address the valve location problem, one of the basic problems in design of long oil pipelines. Whenever a pipeline is depressurized, the shutoff valves block the oil flow and seal the damaged part of the pipeline. Thus, the quantity of oil possibly contaminating the area around the pipeline is determined by the volume of the damaged section of the pipeline between two consecutive valves. Then, ecologic damage can be quantified by the amount of leaked oil and the environmental characteristi...

  10. Bistable (latching) solenoid actuated propellant isolation valve

    Science.gov (United States)

    Wichmann, H.; Deboi, H. H.

    1979-01-01

    The design, fabrication, assembly and test of a development configuration bistable (latching) solenoid actuated propellant isolation valve suitable for the control hydrazine and liquid fluorine to an 800 pound thrust rocket engine is described. The valve features a balanced poppet, utilizing metal bellows, a hard poppet/seat interface and a flexure support system for the internal moving components. This support system eliminates sliding surfaces, thereby rendering the valve free of self generated particles.

  11. 2101-M pond closure plan

    International Nuclear Information System (INIS)

    1993-06-01

    This document describes activities for the closure of a surface impoundment (2101-M Pond) at the Hanford Site. The 2101-H Pond was initially constructed in 1953 to serve as a drainage collection area for the 2101-H Building. (Until the Basalt Waste Isolation Project (BWIP) Laboratory was constructed in the 2101-M Building in 1979--1981, the only source contributing discharge to the pond was condensate water from the 2101-H Building heating, ventilation, and air conditioning (HVAC) system. The drains for the BWIP Laboratory rooms were plumbed into a 4-in., cast-iron, low-pressure drain pipe that carries waste water from the HVAC system to the pond. During the active life of the BWIP Laboratory, solutions of dissolved barium in groundwater samples were discharged to the 2101-M Pond via the laboratory drains. As a result of the discharges, a Part A permit application was initially submitted to the Washington State Department of Ecology (Ecology) in August 1986 which designates the 2101-M Pond as a surface impoundment

  12. Cyanoacrylate for Intraoral Wound Closure: A Possibility?

    Directory of Open Access Journals (Sweden)

    Parimala Sagar

    2015-01-01

    Full Text Available Wound closure is a part of any surgical procedure and the objective of laceration repair or incision closure is to approximate the edges of a wound so that natural healing process may occur. Over the years new biomaterials have been discovered as an alternate to conventional suture materials. Cyanoacrylate bioadhesives are one among them. They carry the advantages of rapid application, patient comfort, resistance to infection, hemostatic properties, and no suture removal anxiety. Hence this study was undertaken to study the effect of long chain cyanoacrylate as an adhesive for intraoral wound closure and also to explore its hemostatic and antibacterial effects. Isoamyl-2-cyanoacrylate (AMCRYLATE was used as the adhesive in the study. In conclusion isoamyl cyanoacrylate can be used for intraoral wound closure, as an alternative to sutures for gluing the mucoperiosteum to bone, for example, after impaction removal, periapical surgeries, and cleft repair. Its hemostatic and antibacterial activity has to be further evaluated.

  13. Reliability assessment of underground shaft closure

    International Nuclear Information System (INIS)

    Fossum, A.F.; Munson, D.E.

    1994-01-01

    The intent of the WIPP, being constructed in the bedded geologic salt deposits of Southeastern New Mexico, is to provide the technological basis for the safe disposal of radioactive Transuranic (TRU) wastes generated by the defense programs of the United States. In determining this technological basis, advanced reliability and structural analysis techniques are used to determine the probability of time-to-closure of a hypothetical underground shaft located in an argillaceous salt formation and filled with compacted crushed salt. Before being filled with crushed salt for sealing, the shaft provides access to an underground facility. Reliable closure of the shaft depends upon the sealing of the shaft through creep closure and recompaction of crushed backfill. Appropriate methods are demonstrated to calculate cumulative distribution functions of the closure based on laboratory determined random variable uncertainty in salt creep properties

  14. 32 CFR 989.25 - Base closure and realignment.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 6 2010-07-01 2010-07-01 false Base closure and realignment. 989.25 Section 989... PROTECTION ENVIRONMENTAL IMPACT ANALYSIS PROCESS (EIAP) § 989.25 Base closure and realignment. Base closure or realignment may entail special requirements for environmental analysis. The permanent base closure...

  15. Transcatheter closure of ventricular septal defect with Occlutech Duct Occluder.

    Science.gov (United States)

    Atik-Ugan, Sezen; Saltik, Irfan Levent

    2018-04-01

    Patent ductus arteriosus occluders are used for transcatheter closure of ventricular septal defects, as well as for closure of patent ductus arteriosus. The Occlutech Duct Occluder is a newly introduced device for transcatheter closure of patent ductus arteriosus. Here, we present a case in which the Occlutech Duct Occluder was successfully used on a patient for the closure of a perimembraneous ventricular septal defect.

  16. Occupancy estimation and the closure assumption

    Science.gov (United States)

    Rota, Christopher T.; Fletcher, Robert J.; Dorazio, Robert M.; Betts, Matthew G.

    2009-01-01

    1. Recent advances in occupancy estimation that adjust for imperfect detection have provided substantial improvements over traditional approaches and are receiving considerable use in applied ecology. To estimate and adjust for detectability, occupancy modelling requires multiple surveys at a site and requires the assumption of 'closure' between surveys, i.e. no changes in occupancy between surveys. Violations of this assumption could bias parameter estimates; however, little work has assessed model sensitivity to violations of this assumption or how commonly such violations occur in nature. 2. We apply a modelling procedure that can test for closure to two avian point-count data sets in Montana and New Hampshire, USA, that exemplify time-scales at which closure is often assumed. These data sets illustrate different sampling designs that allow testing for closure but are currently rarely employed in field investigations. Using a simulation study, we then evaluate the sensitivity of parameter estimates to changes in site occupancy and evaluate a power analysis developed for sampling designs that is aimed at limiting the likelihood of closure. 3. Application of our approach to point-count data indicates that habitats may frequently be open to changes in site occupancy at time-scales typical of many occupancy investigations, with 71% and 100% of species investigated in Montana and New Hampshire respectively, showing violation of closure across time periods of 3 weeks and 8 days respectively. 4. Simulations suggest that models assuming closure are sensitive to changes in occupancy. Power analyses further suggest that the modelling procedure we apply can effectively test for closure. 5. Synthesis and applications. Our demonstration that sites may be open to changes in site occupancy over time-scales typical of many occupancy investigations, combined with the sensitivity of models to violations of the closure assumption, highlights the importance of properly addressing

  17. Fast Flux Test Facility primary sodium valves

    International Nuclear Information System (INIS)

    Rabe, G.B.; Ezra, B.C.

    1977-01-01

    The design and development of the valves used in the primary sodium coolant loop of the Fast Flux Test Facility is described. One tilting-disk check valve is used in the cold leg of the coolant loop. It is designed to limit flow reversal in the loop while maintaining a low pressure drop during forward flow. Two isolation valves are used in each coolant loop--one in the cold leg and one in the hot leg. They are of the motor-operated swinging-gate type. The design, analysis, and testing programs undertaken to develop and qualify these valves are described

  18. Advantages of butterfly valves for power plants

    International Nuclear Information System (INIS)

    Lapadat, J.T.

    1977-01-01

    Butterfly valves are increasingly used in nuclear power plants. They are used in CANDU reactors for class 2 and 3 service, to provide emergency and tight shutoff valves for all inlets and outlets of heat exchangers and all calandria penetrations. Guidelines for meeting nuclear power plant valve specifications are set out in ASME Section 3, Nuclear Power Plant Components. Some details of materials of construction, type of actuator, etc., for various classes of nuclear service are tabulated in the present article. The 'fishtail' butterfly valve is an improved design with reduced drag, as is illustrated and explained. (N.D.H.)

  19. Additively Manufactured Main Fuel Valve Housing

    Science.gov (United States)

    Eddleman, David; Richard, Jim

    2015-01-01

    Selective Laser Melting (SLM) was utilized to fabricate a liquid hydrogen valve housing typical of those found in rocket engines and main propulsion systems. The SLM process allowed for a valve geometry that would be difficult, if not impossible to fabricate by traditional means. Several valve bodies were built by different SLM suppliers and assembled with valve internals. The assemblies were then tested with liquid nitrogen and operated as desired. One unit was also burst tested and sectioned for materials analysis. The design, test results, and planned testing are presented herein.

  20. Safety valve opening and closing operation monitor

    International Nuclear Information System (INIS)

    Kodama, Kunio; Takeshima, Ikuo; Takahashi, Kiyokazu.

    1981-01-01

    Purpose: To enable the detection of the closing of a safety valve when the internal pressure in a BWR type reactor is a value which will close the safety valve, by inputting signals from a pressure detecting device mounted directly at a reactor vessel and a safety valve discharge pressure detecting device to an AND logic circuit. Constitution: A safety valve monitor is formed of a pressure switch mounted at a reactor pressure vessel, a pressure switch mounted at the exhaust pipe of the escape safety valve and a logic circuit and the lide. When the input pressure of the safety valve is raised so that the valve and the pressure switch mounted at the exhaust pipe are operated, an alarm is indicated, and the operation of the pressure switch mounted at a pressure vessel is eliminated. If the safety valve is not reclosed when the vessel pressure is decreased lower than the pressure at which it is to be reclosed after the safety valve is operated, an alarm is generated by the logic circuit since both the pressure switches are operated. (Sekiya, K.)

  1. Outcome of pregnancy in women after pulmonary autograft valve replacement for congenital aortic valve disease

    NARCIS (Netherlands)

    Yap, Sing-Chien; Drenthen, Willem; Pieper, Petronella G.; Moons, Philip; Mulder, Barbara J. M.; Klieverik, Loes M.; Vliegen, Hubert W.; van Dijk, Arie P. J.; Meijboom, Folkert J.; Roos-Hesselink, Jolien W.

    Background and aim of the study: The pulmonary autograft has been recommended as the valve of choice for aortic valve replacement (AVR) in young women contemplating pregnancy. However, current information on maternal and perinatal outcome of pregnancy in women with pulmonary autograft valve

  2. Outcome of pregnancy in women after pulmonary autograft valve replacement for congenital aortic valve disease

    NARCIS (Netherlands)

    Yap, Sing-Chien; Drenthen, Willem; Pieper, Petronella G.; Moons, Philip; Mulder, Barbara J. M.; Klieverik, Loes M.; Vliegen, Hubert W.; van Dijk, Arie P. J.; Meijboom, Folkert J.; Roos-Hesselink, Jolien W.

    2007-01-01

    Background and aim of the study: The pulmonary autograft has been recommended as the valve of choice for aortic valve replacement (AVR) in young women contemplating pregnancy. However, current information on maternal and perinatal outcome of pregnancy in women with pulmonary autograft valve

  3. Outcome of pregnancy in women after pulmonary autograft valve replacement for congenital aortic valve disease.

    NARCIS (Netherlands)

    Yap, S.C.; Drenthen, W.; Pieper, P.G.; Moons, P.; Mulder, B.J.M.; Klieverik, L.M.; Vliegen, H.W.; Dijk, A.P.J. van; Meijboom, F.J.; Roos-Hesselink, J.W.

    2007-01-01

    BACKGROUND AND AIM OF THE STUDY: The pulmonary autograft has been recommended as the valve of choice for aortic valve replacement (AVR) in young women contemplating pregnancy. However, current information on maternal and perinatal outcome of pregnancy in women with pulmonary autograft valve

  4. Transapical JenaValve in a patient with mechanical mitral valve prosthesis.

    LENUS (Irish Health Repository)

    O' Sullivan, Katie E

    2014-01-29

    We report the first case of transcatheter aortic valve replacement implantation using JenaValve™ in a patient with mechanical mitral valve prosthesis. We believe that the design features of this valve may be particularly suited for use in this setting. © 2014 Wiley Periodicals, Inc.

  5. Safety valve including a hydraulic brake and hydraulic brake that could be fitted into a valve

    International Nuclear Information System (INIS)

    Chabat-Courrede, Jean.

    1981-01-01

    Making of a safety valve that can be fitted to a containment vessel filled with a non compressible fluid, such as the water system of a nuclear power station. It includes a hydraulic brake located between the valve and the elastic means, close to the valve which completely suppresses the high frequency oscillations of the equipment [fr

  6. Small valve area index: its influence on early mortality after mitral valve replacement

    NARCIS (Netherlands)

    Yazdanbakhsh, A. P.; van den Brink, R. B.; Dekker, Egbert; de Mol, B. A.

    2000-01-01

    OBJECTIVE: To test the hypothesis that mitral valve prosthesis-patient mismatch increases postoperative mortality. METHODS AND RESULTS: The effect of mitral valve prosthesis-patient mismatch on survival in a cohort of consecutive patients after mitral valve replacement with a mechanical prosthesis

  7. Impact of bicuspid aortic valve on complications and death in infective endocarditis of native aortic valves.

    Science.gov (United States)

    Kahveci, Gokhan; Bayrak, Fatih; Pala, Selcuk; Mutlu, Bulent

    2009-01-01

    We retrospectively investigated the impact of bicuspid aortic valve on the prognosis of patients who had definite infective endocarditis of the native aortic valve.Of 51 patients, a bicuspid aortic valve was present in 22 (43%); the other 29 had tricuspid aortic valves. On average, the patients who had bicuspid valves were younger than those who had tricuspid valves. Patients with a tricuspid valve had larger left atrial diameters and were more likely to have severe mitral regurgitation.Periannular complications, which we detected in 19 patients (37%), were much more common in the patients who had a bicuspid valve (64% vs 17%, P = 0.001). The presence of a bicuspid valve was the only significant independent predictor of periannular complications. The in-hospital mortality rate in the bicuspid group was lower than that in the tricuspid group; however, this figure did not reach statistical significance (9% vs 24%, P = 0.15). In multivariate analysis, left atrial diameter was the only independent predictor associated with an increased risk of death (hazard ratio, 2.19; 95% confidence interval, 1.1-4.5; P = 0.031).In our study, patients with infective endocarditis in a bicuspid aortic valve were younger and had a higher incidence of periannular complications. Although a worse prognosis has been reported previously, we found that infective endocarditis in a native bicuspid aortic valve is not likely to increase the risk of death in comparison with infective endocarditis in native tricuspid aortic valves.

  8. Special closures for steel drum shipping containers

    International Nuclear Information System (INIS)

    Bonzon, L.L.; Otts, J.V.

    1976-01-01

    The objective of this program was to develop special lid closures for typical, steel drum, radioactive material shipping containers. Previous experience and testing had shown that the existing container was adequate to withstand the required environmental tests for certification, but that the lid and closure were just marginally effective. Specifically, the lid closure failed to consistently maintain a tight seal between the container and the lid after drop tests, thus causing the package contents to be vulnerable in the subsequent fire test. Recognizing the deficiency, the United States Energy Research and Development Administration requested the development of new closure(s) which would: (1) be as strong and resistant to a drop as the bottom of the container; (2) have minimal economic impact on the overall container cost; (3) maximize the use of existing container designs; (4) consider crush loads; and (5) result in less dependence on personnel and loading procedures. Several techniques were evaluated and found to be more effective than the standard closure mechanism. Of these, three new closure techniques were designed, fabricated, and proven to be structurally adequate to provide containment when a 454-kg drum was drop tested from 9.14-m onto an unyielding surface. The three designs were: (1) a 152-mm long lid extension or skirt welded to the standard drum lid, (2) a separate inner lid, with 152-mm long skirt and (3) C-clamps used at the container-lid interface. Based upon structural integrity, economic impact, and minimal design change, the lid extension is the recommended special closure

  9. Factors affecting closure of a temporary stoma.

    Science.gov (United States)

    Taylor, Claire; Varma, Sarah

    2012-01-01

    The purpose of the study was to examine time to reversal of a temporary ostomy, reasons for delayed closure, and patient satisfaction with the scheduling of their closure and related hospital care. Cross-sectional, descriptive study. The target population comprised patients who underwent creation of a temporary ostomy and reversal surgery within one National Health System Hospital Trust in the United Kingdom. The population served by this Trust are ethnically and socioeconomically diverse, predominantly living in urban areas around Greater London. Sixty-one persons who met inclusion criteria were identified. A two-step analytical process was undertaken. First, a literature review examining incidence and causes of delayed stoma closure was undertaken. Second, a postal survey of all patients who had had their stoma closed in 2009 was conducted. Respondents were allowed 2 weeks to complete and return the questionnaire. The survey instrument was developed locally and subjected to content validation using ostomy patients, surgical and nursing colleagues. It consisted of 9 questions querying time from original surgery to closure, reasons for delaying closure surgery beyond 12 weeks, and satisfaction with care. Twenty-seven patients returned their questionnaires, indicating they consented to participate; a response rate of 44%. Half of the respondents (n = 14 [52%]) underwent closure surgery within 6 months of stoma formation; the remaining 48% waited more than 6 months (median: 6.5 months, range: 1.5-26 months). Thirteen patients (48%) reported a delay in receiving their stoma closure; the main reason cited was the need for a course of adjuvant postoperative chemotherapy. Three quarters of respondents (22 [74%]) were satisfied with the overall care they received. Findings from this study suggest that stoma closure may be associated with fewest complications if performed before 12 weeks.

  10. ASD Closure in Structural Heart Disease.

    Science.gov (United States)

    Wiktor, Dominik M; Carroll, John D

    2018-04-17

    While the safety and efficacy of percutaneous ASD closure has been established, new data have recently emerged regarding the negative impact of residual iatrogenic ASD (iASD) following left heart structural interventions. Additionally, new devices with potential advantages have recently been studied. We will review here the potential indications for closure of iASD along with new generation closure devices and potential late complications requiring long-term follow-up. With the expansion of left-heart structural interventions and large-bore transseptal access, there has been growing experience gained with management of residual iASD. Some recently published reports have implicated residual iASD after these procedures as a potential source of diminished clinical outcomes and mortality. Additionally, recent trials investigating new generation closure devices as well as expanding knowledge regarding late complications of percutaneous ASD closure have been published. While percutaneous ASD closure is no longer a novel approach to managing septal defects, there are several contemporary issues related to residual iASD following large-bore transseptal access and new generation devices which serve as an impetus for this review. Ongoing attention to potential late complications and decreasing their incidence with ongoing study is clearly needed.

  11. Percutaneous Transcatheter PDA Device Closure in Infancy

    International Nuclear Information System (INIS)

    Ullah, M.; Sultan, M.; Akhtar, K.; Sadiq, N.; Akbar, H.

    2014-01-01

    Objective: To evaluate the results and complications associated with transcatheter closure of patent ductus arteriosus (PDA) in infants. Study Design: Quasi-experimental study. Place and Duration of Study: Paediatric Cardiology Department of Armed Forces Institute of Cardiology / National Institute of Heart Diseases (AFIC/NIHD), Rawalpindi, from December 2010 to June 2012. Methodology: Infants undergoing transcatheter device closure of PDA were included. All patients were evaluated by experienced Paediatric Cardiologists with 2-D echocardiography and Doppler before the procedure. Success of closure and complications were recorded. Results: The age of patients varied from 05 - 12 months and 31 (56.4%) were females. Out of the 55 infants, 3 (5.4%) were not offered device closure after aortogram (two large tubular type ducts and one tiny duct, considered unsuitable for device closure); while in 50 (96.1%) patients out of remaining 52, the duct was successfully closed with transcatheter PDA device or coil. In one infant, device deployment resulted in acquired coarctation, necessitating device retrieval by Snare followed by surgical duct interruption and another patient had non-fatal cardiac arrest during device deployment leading to abandonment of procedure and subsequent successful surgical interruption. Local vascular complications occurred in 12 (21.8%) of cases and all were satisfactorily treated. Conclusion: Transcatheter device closure of PDA in infants was an effective procedure in the majority of cases; however, here were considerable number of local access site vascular complications. (author)

  12. Hydraulic engine valve actuation system including independent feedback control

    Science.gov (United States)

    Marriott, Craig D

    2013-06-04

    A hydraulic valve actuation assembly may include a housing, a piston, a supply control valve, a closing control valve, and an opening control valve. The housing may define a first fluid chamber, a second fluid chamber, and a third fluid chamber. The piston may be axially secured to an engine valve and located within the first, second and third fluid chambers. The supply control valve may control a hydraulic fluid supply to the piston. The closing control valve may be located between the supply control valve and the second fluid chamber and may control fluid flow from the second fluid chamber to the supply control valve. The opening control valve may be located between the supply control valve and the second fluid chamber and may control fluid flow from the supply control valve to the second fluid chamber.

  13. A shut-off valve for flexible tubing

    Science.gov (United States)

    Reyburn, W. W.

    1972-01-01

    Design of light weight valve for flexible tubing is described. Valve is hand operated and provides positive sealing in normally closed position. Diagram is provided to show construction of valve. Principles of operation are explained.

  14. 105-DR Large Sodium Fire Facility closure activities evaluation report

    International Nuclear Information System (INIS)

    Adler, J.G.

    1996-01-01

    This report evaluates the closure activities at the 105-DR Large Sodium Fire Facility. The closure activities discussed include: the closure activities for the structures, equipment, soil, and gravel scrubber; decontamination methods; materials made available for recycling or reuse; and waste management. The evaluation compares these activities to the regulatory requirements and closure plan requirements. The report concludes that the areas identified in the closure plan can be clean closed

  15. Primary closure in colon trauma.

    Science.gov (United States)

    Salinas-Aragón, Luis Enrique; Guevara-Torres, Lorenzo; Vaca-Pérez, Enrique; Belmares-Taboada, Jaime Arístides; Ortiz-Castillo, Fátima de Guadalupe; Sánchez-Aguilar, Martín

    2009-01-01

    Primary repair of colon injuries is an accepted therapeutic option; however, controversy persists regarding its safety. Our objective was to report the evolution and presence of complications in patients with colon injury who underwent primary closure and to determine if the time interval (>6 h), degree of injury, contamination, anatomic site injured, PATI (Penetrating Abdominal Trauma Index) >25, and the presence of other injuries in colon trauma are associated with increased morbidity and mortality. This was a prospective, observational, longitudinal and descriptive study conducted at the Central Hospital "Dr. Ignacio Morones Prieto," San Luis Potosí, Mexico, from January 1, 2003 to December 31, 2007. We included patients with abdominal trauma with colon injury subjected to surgical treatment. chi(2) was used for basic statistical analysis. There were 481 patients with abdominal trauma who underwent surgery; 77(16.1%) had colon injury. Ninety percent (n = 69) were treated in the first 6 h; 91% (n = 70) were due to penetrating injuries, and gunshot wound accounted for 48% (n = 37). Transverse colon was the most frequently injured (38%) (n = 29). Grade I and II injuries accounted for 75.3% (n = 58). Procedures included primary repair (76.66 %) (n = 46); resection with anastomosis (8.3%) (n = 5); and colostomy (15%) (n = 9). Associated injuries were present in 76.6% (n = 59). There was some degree of contamination in 85.7% (n = 66); 82.8% (58) had PATI colon injury. Primary repair is a safe procedure for treatment of colon injuries. Patients with primary repair had lower morbidity (p <0.009). Surgery during the first 6 h (p <0.006) and in hemodynamically stable patients (p <0.014) had a lower risk of complications.

  16. Accelerating cleanup: Paths to closure

    International Nuclear Information System (INIS)

    1998-06-01

    This report describes the status of Environmental Management's (EM's) cleanup program and a direction forward to complete achievement of the 2006 vision. Achieving the 2006 vision results in significant benefits related to accomplishing EM program objectives. As DOE sites accelerate cleanup activities, risks to public health, the environment, and worker safety and health are all reduced. Finding more efficient ways to conduct work can result in making compliance with applicable environmental requirements easier to achieve. Finally, as cleanup activities at sites are completed, the EM program can focus attention and resources on the small number of sites with more complex cleanup challenges. Chapter 1 describes the process by which this report has been developed and what it hopes to accomplish, its relationship to the EM decision-making process, and a general background of the EM mission and program. Chapter 2 describes how the site-by-site projections were constructed, and summarizes, for each of DOE's 11 Operations/Field Offices, the projected costs and schedules for completing the cleanup mission. Chapter 3 presents summaries of the detailed cleanup projections from three of the 11 Operations/Field Offices: Rocky Flats (Colorado), Richland (Washington), and Savannah River (South Carolina). The remaining eight Operations/Field Office summaries are in Appendix E. Chapter 4 reviews the cost drivers, budgetary constraints, and performance enhancements underlying the detailed analysis of the 353 projects that comprise EM's accelerated cleanup and closure effort. Chapter 5 describes a management system to support the EM program. Chapter 6 provides responses to the general comments received on the February draft of this document

  17. Resurgery for recurrent heart valve diseases

    Directory of Open Access Journals (Sweden)

    Chong-lei REN

    2017-02-01

    Full Text Available Objective To summarize the experience with resurgery for recurrent valvular heart diseases. Methods From June 2004 to June 2015, 28 patients (15 males and 13 females with ages ranging from 44 to 67 years (55.6±6.5 years with recurrent heart valve disease underwent resurgery. The reasons for resurgery included perivalvular leakage (7 cases, bioprosthetic valve decline (6 cases in mitral valve and 3 in tricuspid valve, mechanical prostheses dysfunction (2cases, infective endocarditis after valve replacement (2 cases, restenosis of repaired native valve (1 case, and severe tricuspid insufficiency after left-side valve surgery (7 cases. Resurgery included mitral valve replacement in 18 patients and tricuspid valve replacement in 10. All the patients underwent third or fourth or even fifth cardiac surgery for valve replacement. Results There were 2 hospital deaths with a mortality of 7.1% (2/28. The main causes of early-stage deaths were low cardiac output syndrome. The main postoperative complications were respiratory failure in 3, low cardiac output syndrome in 2, reexploration for bleeding in 2 and serious infectious shock in 1. All the patients were found with the great improvement in heart function and the re-implanted prostheses worked well during follow-up. Conclusions Although resurgery for recurrent heart valve disease poses a continuing challenge to cardiac surgeon, it could be performed with the satisfactory results. The keys to a successful cardiac resurgery include appropriate operational timing, refined surgical technique and reasonable perioperative managements. DOI: 10.11855/j.issn.0577-7402.2017.01.11

  18. Multidetector computed tomography sizing of bioprosthetic valves: guidelines for measurement and implications for valve-in-valve therapies

    International Nuclear Information System (INIS)

    Rajani, R.; Attia, R.; Condemi, F.; Webb, J.; Woodburn, P.; Hodson, D.; Nair, A.; Preston, R.; Razavi, R.; Bapat, V.N.

    2016-01-01

    Aim: To describe a technique for bioprosthetic multidetector computed tomography (MDCT) sizing and to compare MDCT-derived values against manufacturer-provided sizing. Materials and methods: Fourteen bioprosthetic stented valves commonly used in the aortic valve position were evaluated using a Philips 256 MDCT system. All valves were scanned using a dedicated cardiac CT protocol with a four-channel electrocardiography (ECG) simulator. Measurements were made of major and minor axes and the area and perimeter of the internal stent using varying reconstruction kernels and window settings. Measurements derived from MDCT (MDCT ID) were compared against the stent internal diameter (Stent ID) as provided by the valve manufacturer and the True ID (Stent ID + insertion of leaflets). All data were collected and analysed using SPSS for Mac (version 21). Results: The mean difference between the MDCT ID and Stent ID was 0.6±1.9 mm (r=0.649, p=0.012) and between MDCT ID and True ID 2.1±2 mm (r=0.71, p=0.005). There was no difference in the major (p=0.90), minor (p=0.87), area (p=0.92), or perimeter (p=0.92) measurements when sharp, standard, and detailed stent kernels were used. Similarly, the measurements remained consistent across differing windowing levels. Conclusion: Bioprosthetic stented valves may be reliably sized using MDCT in patients requiring valve-in-valve (VIV) interventions where the valve type and size are unknown. In these cases, clinicians should be aware that MDCT has a tendency to overestimate the True ID size. - Highlights: • Cardiac CT is likely to be ideally suited for bioprosthetic aortic valve sizing for valve in valve procedures. • We compared MDCT sizing for 14 varying bioprosthetic aortic valves across varying window settings and reconstruction kernels. • We provide “normal” MDCT sizing for varying valves and show their relationship to surgical sizing. • Bioprosthetic valves may be reliably sized by MDCT but require adjustment owing to

  19. Transcatheter valve-in-valve implantation due to severe aortic regurgitation in a degenerated aortic homograft

    DEFF Research Database (Denmark)

    Olsen, Lene Kjaer; Engstrøm, Thomas; Søndergaard, Lars

    2009-01-01

    Transcatheter aortic valve implantation (TAVI) in severe aortic stenosis has proven to be a feasible and effective treatment modality for inoperable patients. Until now, neither aortic regurgitation nor degenerated bioprostheses has been an indication for TAVI. However, this article reports...... a successful valve-in-valve implantation of a CoreValve aortic valve prosthesis through the right subclavian artery in a case of severe aortic regurgitation within a degenerated aortic homograft. The case exemplifies the possibilities of expanding the indications for TAVI, as well as other vascular access...

  20. Gasoline New Timing and Flux Adjustable Rotary Valve Design (Hereinafter: Rotary Valve

    Directory of Open Access Journals (Sweden)

    Du huiqi

    2016-01-01

    Full Text Available Conventional gasoline engine with an umbrella valve control cylinder intake and exhaust, in order to achieve sealing effect, the valve is driven by the spring force; at the same time, when the cam opens the valve to overcome the spring force acting. Sealing the better, the more power consumed in the engine mechanical losses, the valve mechanism consumes about 30%, which is not a small loss! This article describes a new type of rotary valve is to significantly reduce mechanical losses, so as to achieve energy saving purposes.

  1. Role of vesicostomy in the management of posterior urethral valve in Sub-Saharan Africa.

    Science.gov (United States)

    Lukong, C S; Ameh, E A; Mshelbwala, P M; Jabo, B A; Gomna, A; Anumah, M A; Nmadu, P T; Mfuh, A Y

    2014-02-01

    To review the role of vesicostomy in the management of posterior urethral valve (PUV), in neonates and infants, given the limitations for endoscopic treatment in this setting. A review of 35 patients who presented with posterior urethral valve over a 10-year period. Demographic and clinical information were prospectively recorded on a structured pro forma, and the data extracted analysed using SPSS 11.0. The 35 boys were aged 3 days to 10 years (median 3 weeks). Twenty-three (65.7%) had a vesicostomy (age range 3 days-3 years, median 3 weeks). The mode of presentation was poor urinary stream 15 (65.2%), urinary retention 4 (17.4%), and renal failure 6 (26.1%). Main findings were palpable bladder 23 (100%), hydronephrosis 4 (17.4%). Abdominal ultrasound confirmed hydronephrosis and thickened bladder wall, and voiding/expressive cystourethrogram confirmed dilated posterior urethra and vesicoureteric reflux in all 23 patients. Complications following vesicostomy were stoma stenosis 1 (4.3%), bladder mucosal prolapse 1 (4.3%), perivesicostomy abscess 1 (4.3%); there was no mortality. Following vesicostomy, 10 (43.5%) patients had excision of the valves and vesicostomy closure at age 2-8 years (median 4 years). They are well, with normal renal ultrasonographic findings, bladder capacity range 115-280 ml, and normal urea, serum electrolytes, creatinine, at 3 years of follow up. Thirteen (56.5%) are still awaiting valvotomy but have remained well and with normal ultrasonographic renal findings. Vesicostomy is a useful temporising mode of urinary diversion in neonates and infants with posterior urethral valve (in the absence of unobstructed upper tracts) when facilities for endoscopic valve ablation are not readily available. Copyright © 2013 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.

  2. High Reliability Cryogenic Piezoelectric Valve Actuator, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Cryogenic fluid valves are subject to harsh exposure and actuators to drive these valves require robust performance and high reliability. DSM's piezoelectric...

  3. Dikkers Valves for nuclear industry

    International Nuclear Information System (INIS)

    Anon.

    1975-01-01

    Most countries have adopted the ASME Boiler and Pressure Vessel Code Section III, as the basis of their national requirements for licensing nuclear components. This Code gives clear directives for defining design requirements coupled with a controlled manufacturing system. It has always been and still is the policy of Dikkers to manufacture high-quality products. Dikkers manufacture nuclear products in accordance with this Code, Section III; indeed many features exceed these minimum requirements. At the Nuclex Exhibition in Basel, Dikkers Valves BV will exhibit its main products for use in nuclear power plants. (Auth.)

  4. Cylinder valve packing nut studies

    Energy Technology Data Exchange (ETDEWEB)

    Blue, S.C. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    The design, manufacture, and use of cylinder valve packing nuts have been studied to improve their resistance to failure from stress corrosion cracking. Stress frozen photoelastic models have been analyzed to measure the stress concentrations at observed points of failure. The load effects induced by assembly torque and thermal expansion of stem packing were observed by strain gaging nuts. The effects of finishing operations and heat treatment were studied by the strain gage hole boring and X-ray methods. Modifications of manufacturing and operation practices are reducing the frequency of stress corrosion failures.

  5. Valve Corporation: Composing Internal Markets

    OpenAIRE

    Todd R. Zenger

    2015-01-01

    Discussions of the Valve Corporation are always enlightening. The skeptic wonders how much is rhetoric and recruiting ploy and how much is real. Is there clear evidence that this organizational design actually works – that it is efficient in this setting? While revenues per employee are quite remarkable, cause and effect are unclear. Is “boss-less-ness” the cause of high sales per employee or simply the result of high sales per employee, fueled from earlier success? The same question could be...

  6. Retrospective analysis of transthoracic echocardiography about the failure of transcather closure of ventricular septal defect

    International Nuclear Information System (INIS)

    Zhang Yigang; Li Shijie; Liu Ru; Li Zhihong; Fu Qiang

    2008-01-01

    Objective: To evaluate the value of echocardiography in investigation the failure of interventional therapy of VSDs and to increase the successful rate. Methods: 15 cases with failure of VSD closure through interventional approach were undertaken measurement of major parameters of the defect on left ventriculography and then followed by Philips 5500 color Doppler US for repeated multi-direction tangential measuring of the size, morphologic change, relation with peripheral structure and individual valvular regurgitation. Results: (1) Marginal membranous VSD 10 eases; membranance aneurysm 8 cases, ≥ 2 outlets 6 cases. Width of basal part of membranous aneurysm was 8-18 (10±2) mm with depth of 3 10 (6±2) mm, distance from aortic valve was 0-6 (2±1) mm and from tricuspid valve was 2-5 (2±1) mm; associated with slight tricuspid valvular regurgitation. Aortic valvular regurgitation 5 cases showed slight to mild amount and without membranous aneurysm occurred in 2 cases. (2) Intracristal VSD 5 cases showed the size of defect as 6-10 (7±1) mm, with distances of 2-3 (1±0.8) mm from pulmonary valve and 1-2 (1±0.6) mm from aortic valve associated with slight regurgitation in 4 cases, slight tricuspid valvular regurgitation in 5 eases and aortic valvular prolapse in 4 cases. Conclusions: Many factors can influence the direction tangential continuous scanning should be taken for accurate localization and measurement of VSD in order to select the very sight occludor providing high successful rate of occlusion and long term efficacy. (authors)

  7. Transcatheter aortic valve-in-valve treatment of degenerative stentless supra-annular Freedom Solo valves: A single centre experience.

    Science.gov (United States)

    Cockburn, James; Dooley, Maureen; Parker, Jessica; Hill, Andrew; Hutchinson, Nevil; de Belder, Adam; Trivedi, Uday; Hildick-Smith, David

    2017-02-15

    Redo surgery for degenerative bioprosthetic aortic valves is associated with significant morbidity and mortality. Report results of valve-in-valve therapy (ViV-TAVI) in failed supra-annular stentless Freedom Solo (FS) bioprostheses, which are the highest risk for coronary occlusion. Six patients with FS valves (mean age 78.5 years, 50% males). Five had valvular restenosis (peak gradient 87.2 mm Hg, valve area 0.63 cm 2 ), one had severe regurgitation (AR). Median time to failure was 7 years. Patients were high risk (mean STS/Logistic EuroScore 10.6 15.8, respectively). FS valves ranged from 21 to 25 mm. Successful ViV-TAVI was achieved in 4/6 patients (67%). Of the unsuccessful cases, (patient 1 and 2 of series) patient 1 underwent BAV with simultaneous aortography which revealed left main stem occlusion. The procedure was stopped and the patient went forward for repeat surgery. Patient 2 underwent successful ViV-TAVI with a 26-mm CoreValve with a guide catheter in the left main, but on removal coronary obstruction occurred, necessitating valve snaring into the aorta. Among the successful cases, (patients 3, 4, 5, 6) the TAVIs used were CoreValve Evolut R 23 mm (n = 3), and Lotus 23 mm (n = 1). In the successful cases the peak gradient fell from 83.0 to 38.3 mm Hg. No patient was left with >1+ AR. One patient had a stroke on Day 2, with full neurological recovery. Two patients underwent semi-elective pacing for LBBB and PR >280 ms. ViV-TAVI in stentless Freedom Solo valves is high risk. The risk of coronary occlusion is high. The smallest possible prosthesis (1:1 sizing) should be used, and strategies to protect the coronary vessels must be considered. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  8. A Simple and Robust Sliding Mode Velocity Observer for Moving Coil Actuators in Digital Hydraulic Valves

    DEFF Research Database (Denmark)

    Nørgård, Christian; Schmidt, Lasse; Bech, Michael Møller

    2016-01-01

    This paper focuses on estimating the velocity and position of fast switching digital hydraulic valves actuated by electromagnetic moving coil actuators, based on measurements of the coil current and voltage. The velocity is estimated by a simple first-order sliding mode observer architecture...... and the position is estimated by integrating the estimated velocity. The binary operation of digi-valves enables limiting and resetting the position estimate since the moving member is switched between the mechanical end-stops of the valve. This enables accurate tracking since drifting effects due to measurement...... noise and integration of errors in the velocity estimate may be circumvented. The proposed observer architecture is presented along with stability proofs and initial experimental results. To reveal the optimal observer performance, an optimization of the observer parameters is carried out. Subsequently...

  9. Structural valve deterioration in a starr-edwards mitral caged-disk valve prosthesis.

    Science.gov (United States)

    Aoyagi, Shigeaki; Tayama, Kei-Ichiro; Okazaki, Teiji; Shintani, Yusuke; Kono, Michitaka; Wada, Kumiko; Kosuga, Ken-Ichi; Mori, Ryusuke; Tanaka, Hiroyuki

    2013-01-01

    The durability of the Starr-Edwards (SE) mitral caged-disk valve, model 6520, is not clearly known, and structural valve deterioration in the SE disk valve is very rare. Replacement of the SE mitral disk valve was performed in 7 patients 23-40 years after implantation. Macroscopic examination of the removed disk valves showed no structural abnormalities in 3 patients, in whom the disk valves were removed at valves excised >36 years after implantation in 4 patients. Disk fracture, a longitudinal split in the disk along its circumference at the site of incorporation of the titanium ring, was detected in the valves removed 36 and 40 years after implantation, respectively, and many cracks were also observed on the outflow aspect of the disk removed 40 years after implantation. Disk fracture and localized disk wear were found in the SE mitral disk valves implanted >36 years previously. The present results suggest that SE mitral caged-disk valves implanted >20 years previously should be carefully followed up, and that those implanted >30 years previously should be electively replaced with modern prosthetic valves

  10. Maximizing prosthetic valve size with the Top Hat supra-annular aortic valve

    DEFF Research Database (Denmark)

    Aagaard, Jan; Geha, Alexander S.

    2007-01-01

    BACKGROUND AND AIM OF THE STUDY: The CarboMedics Top Hat supra-annular aortic valve allows a one-size (and often two-size) increase over the standard intra-annular valve. This advantage should minimize the risk of patient-prosthesis mismatch, where the effective prosthetic valve orifice area....... This study evaluates the authors' clinical experience with Top Hat supra-annular aortic valve size selection, and the technical aspects of implantation. METHODS: Between January 1999 and October 2005, a total of 251 consecutive patients underwent 252 aortic valve replacements with Top Hat supra...... required unplanned coronary bypass, and 30-day mortality was 2.0% (5/251), indicating a good safety profile for the valves implanted in this series. CONCLUSION: The general distribution of implant sizes in the US indicates that cardiac surgeons may be under-sizing the Top Hat supra-annular aortic valve...

  11. 40 CFR 264.228 - Closure and post-closure care.

    Science.gov (United States)

    2010-07-01

    ... remaining wastes to a bearing capacity sufficient to support final cover; and (iii) Cover the surface....112 must include both a plan for complying with paragraph (a)(1) of this section and a contingent plan... practicably removed at closure; and (ii) The owner or operator must prepare a contingent post-closure plan...

  12. Post-operative analgesic requirement in non-closure and closure of peritoneum during open appendectomy

    International Nuclear Information System (INIS)

    Khan, A.W.; Maqsood, R.; Saleem, M.M.

    2017-01-01

    To compare the mean post-operative analgesic requirement in non-closure and closure of peritoneum during open appendectomy. Study Design: Randomized controlled trial. Place and Duration of Study: Department of General Surgery Combined Military Hospital Quetta, from 1st August 2014 to 30th April 2015. Material and Methods: A total of 60 patients were included in this study and were divided into two groups of 30 each. Patients in group A underwent open appendectomy with closure of peritoneum while patients in group B had non-closure of peritoneum during the same procedure. Post-operatively, pain severity was assessed on visual analogue scale (VAS) numeric pain distress scale. On presence of VAS numeric pain distress scale between 5 to 7, intramuscular (IM) diclofenac sodium was given and on score >7, intravascular (IV) tramadol was given. The final outcome was measured at day 0 and day 1. Results: Pain score and analgesic requirements were significantly less in non-closure group than closure group on day 0 and day 1, showing statistically significant difference between the two groups. Conclusion: Mean post-operative analgesic requirement is significantly less in non-closure group as compared to closure group during open appendectomy. (author)

  13. Anatomical challenges for transcatheter mitral valve intervention

    DEFF Research Database (Denmark)

    De Backer, Ole; Luk, Ngai H V; Søndergaard, Lars

    2016-01-01

    Following the success of transcatheter aortic and pulmonary valve implantation, there is a large interest in transcatheter mitral valve interventions to treat severe mitral regurgitation (MR). With the exception for the MitraClipTM (Abbott, Abbott Park, IL, USA) edge-to-edge leaflet plication...

  14. Transcatheter Aortic Valve Replacement in Europe

    DEFF Research Database (Denmark)

    Mylotte, Darren; Osnabrugge, Ruben L J; Windecker, Stephan

    2013-01-01

    The authors sought to examine the adoption of transcatheter aortic valve replacement (TAVR) in Western Europe and investigate factors that may influence the heterogeneous use of this therapy.......The authors sought to examine the adoption of transcatheter aortic valve replacement (TAVR) in Western Europe and investigate factors that may influence the heterogeneous use of this therapy....

  15. Oil pipeline valve automation for spill reduction

    Energy Technology Data Exchange (ETDEWEB)

    Mohitpour, Mo; Trefanenko, Bill [Enbridge Technology Inc, Calgary (Canada); Tolmasquim, Sueli Tiomno; Kossatz, Helmut [TRANSPETRO - PETROBRAS Transporte S.A., Rio de Janeiro, RJ (Brazil)

    2003-07-01

    Liquid pipeline codes generally stipulate placement of block valves along liquid transmission pipelines such as on each side of major river crossings where environmental hazards could cause or are foreseen to potentially cause serious consequences. Codes, however, do not stipulate any requirement for block valve spacing for low vapour pressure petroleum transportation, nor for remote pipeline valve operations to reduce spills. A review of pipeline codes for valve requirement and spill limitation in high consequence areas is thus presented along with a criteria for an acceptable spill volume that could be caused by pipeline leak/full rupture. A technique for deciding economically and technically effective pipeline block valve automation for remote operation to reduce oil spilled and control of hazards is also provided. In this review, industry practice is highlighted and application of the criteria for maximum permissible oil spill and the technique for deciding valve automation thus developed, as applied to ORSUB pipeline is presented. ORSUB is one of the three initially selected pipelines that have been studied. These pipelines represent about 14% of the total length of petroleum transmission lines operated by PETROBRAS Transporte S.A. (TRANSPETRO) in Brazil. Based on the implementation of valve motorization on these three pipeline, motorization of block valves for remote operation on the remaining pipelines is intended, depending on the success of these implementations, on historical records of failure and appropriate ranking. (author)

  16. Nuclear valves and the licencing authority

    International Nuclear Information System (INIS)

    Stevens-Guille, P.D.

    1977-02-01

    Valve problems relevant to licencing authorities are discussed. It is suggested that the probability of valve failure should be given more emphasis in safety analysis. Problems of stress analysis, codes, seismic effects, malfunction and leakage are discussed and programmes aimed at solving future problems are outlined

  17. The future of transcatheter mitral valve interventions

    DEFF Research Database (Denmark)

    Maisano, Francesco; Alfieri, Ottavio; Banai, Shmuel

    2015-01-01

    of transcatheter mitral valve interventions will be. The purpose of the present report is to review the current state-of-the-art of mitral valve intervention, and to identify the potential future scenarios, which might benefit most from the transcatheter repair and replacement devices under development....

  18. Mitral valve prolapse - report of 3 cases

    International Nuclear Information System (INIS)

    Han, Moon Hee; Im, Chung Ki; Im, Dong Ran; Han, Man Chung; Lee, Young Woo; Seo, Jung Don

    1979-01-01

    Prolapse of mitral valve is characterized by its unique auscultatory, echocardiographic and angiographic findings and may be associated with various disease entities such as congenital heart disease, coronary heart disease and Marfan's syndrome etc. Authors report recent experience of 3 cases of prolapsed mitral valve, 2 cases associated with A.S.D. and 1 case with Marfan's syndrome.

  19. Altitude valve for railway suspension control system

    Science.gov (United States)

    Zhang, Xuan; Zhang, Lihao; Li, Qingxuan; Chen, WanSong

    2017-09-01

    With the variation of people and material during vehicle service, the gravity of vehicle could be unbalanced. As a result it might cause accident. In order to solve this problem, altitude valve is assembled on board. It can adjust the gravity of vehicle by the intake and outlet progress of the spring in the altitude valve to prevent the tilt of vehicles.

  20. Bentall Operation with Valved Homograft Conduit

    Science.gov (United States)

    Choudhary, Shiv K.; Talwar, Sachin; Kumar, A. Sampath

    2000-01-01

    Lesions of the ascending aorta associated with aortic valve disease are usually treated by implanting a prosthetic valved conduit (Bentall procedure). In this report, we present our experience in which a valved homograft conduit was used for the procedure. Six patients underwent a Bentall procedure with the use of a cryopreserved valved homograft conduit. Two of the patients had annuloaortic ectasia, 2 had Marfan syndrome, and 1 had an atherosclerotic aneurysm of the aorta. One patient had severe aortic stenosis due to a bicuspid aortic valve, along with an aneurysm and localized dissection of the ascending aorta. In all of the patients, the aortic annulus was substantially dilated, with accompanying moderate-to-severe aortic regurgitation. A standard procedure was performed with moderate hypothermia, cardiopulmonary bypass, and aortic and bicaval cannulation. The ascending aorta and the aortic valve were replaced with a cryopreserved valved homograft conduit (aortic in 5 patients and pulmonary in 1). The native coronary ostia were anastomosed directly to the homograft. Echocardiography, which was performed intraoperatively, before discharge from the hospital, and at follow-up visits (1 to 36 months), revealed good valve function without dilatation of the homograft conduits. There was 1 late death due to Aspergillus fumigatus endocarditis, 6 months postoperatively. In 1 patient, magnetic resonance imaging performed at 24 months revealed normal caliber of the homograft conduit. We conclude that the Bentall procedure can be performed, safely and with excellent results, using cryopreserved homograft conduits. PMID:11198310

  1. 14 CFR 25.995 - Fuel valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel valves. 25.995 Section 25.995 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System Components § 25.995 Fuel valves. In addition...

  2. 14 CFR 29.995 - Fuel valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel valves. 29.995 Section 29.995 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Fuel System Components § 29.995 Fuel valves. In addition...

  3. 14 CFR 27.995 - Fuel valves.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel valves. 27.995 Section 27.995 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Fuel System Components § 27.995 Fuel valves. (a) There must...

  4. Heart valve disease among patients with hyperprolactinemia

    DEFF Research Database (Denmark)

    Steffensen, Maria Charlotte; Maegbaek, Merete Lund; Laurberg, Peter

    2012-01-01

    Increased risk of heart valve disease during treatment with certain dopamine agonists, such as cabergoline, has been observed in patients with Parkinson's disease. The same compound is used to treat hyperprolactinemia, but it is unknown whether this also associates with heart valve disease....

  5. Evolving Concepts in Transcatheter Aortic Valve Implantation

    NARCIS (Netherlands)

    Nijhoff, F.

    2015-01-01

    Part I of the present thesis is dedicated to implantation technique and the clinical performance of new valve prostheses. A satisfactory TAVI result not solely depends on patient characteristics, but also relies on proper valve positioning and final placement. Moreover, prosthetic design is

  6. Hardfacing materials and processes for valve applications

    International Nuclear Information System (INIS)

    Matthews, S.J.; Crook, P.

    1982-01-01

    The subject of hardfacing is a very high technology effort especially in the valve industry. The technology is manifested by the need for sophisticated high performance hardfacing alloys required to resist the demanding environments of fluid flow control valve service. High technology is also found in the automated methods currently being used to efficiently deposit high quality hardfacing overlays. 3 figures, 3 tables

  7. Heart valve replacements with regenerative capacity

    NARCIS (Netherlands)

    Dijkman, P.E.; Fioretta, E.S.; Frese, L.; Pasqualini, F.S.; Hoerstrup, S.P.

    2016-01-01

    The incidence of severe valvular dysfunctions (e.g., stenosis and insufficiency) is increasing, leading to over 300,000 valves implanted worldwide yearly. Clinically used heart valve replacements lack the capacity to grow, inherently requiring repetitive and high-risk surgical interventions during

  8. Sealing a Loosely Fitting Valve Assembly

    Science.gov (United States)

    Goff, L.; Tellier, G.

    1986-01-01

    Double-ring seal avoids expense of remachining or redesigning valve parts. Mating fittings on valve sealed by pair of rings - one O-ring and backup ring. Backup ring fills relatively large gap between parts. Prevents softer O-ring from being pushed into and through gap.

  9. Butterfly valves: greater use in power plants

    International Nuclear Information System (INIS)

    McCoy, M.

    1975-01-01

    Improvements in butterfly valves, particularly in the areas of automatic control and leak tightness are described. The use of butterfly valves in nuclear power plants is discussed. These uses include service in component cooling, containment cooling, and containment isolation. The outlook for further improvements and greater uses is examined. (U.S.)

  10. Controllable valve in a nuclear reactor system

    International Nuclear Information System (INIS)

    Schabert, H.P.; Laurer, E.

    1980-01-01

    The quick-acting gate valve of the PWR is opened and closed by means of two pistons and live steam. One of the pistons is connected to the valve disk by a piston rod which is concentrically lead into another hollow piston rod being connected to the second piston. Stops limit the strokes of the two pistons. (GL) [de

  11. How to insure quality valve remanufacture

    International Nuclear Information System (INIS)

    Scott, C.F.

    1991-01-01

    The importance of quality valve repair for the power generation industry is an obvious need for both the owner as well as the consumer. Whether valves are repaired in-line, on-site, or at a valve remanufacturing facility, the selection of a vendor is vital to meeting not only stringent quality requirements, but also to meet start-up schedules and budgets. In the past, the rule of thumb was that repair of a valve could cost approximately 50% of the cost of a new valve and still represent a significant savings to the end user. For power generation facilities, the fact that many valves are welded in not only makes repair more economical, but even vital to continuing normal operations. For those items not welded in, long lead times and higher prices for these normally exotic alloys make remanufactured valves even more attractive. However, even as these advantages of remanufacturing are obvious, some repair organizations continue to cut corners to meet profit demands. The result is suspect quality in some valves. This can lead to premature failures, possible reduced generating capacity, unscheduled outages, and even catastrophic results. Therefore, the choice of a repair organization must be made with care. As the author has said, repair is an obvious option, but the procurement should definitely involve more than just price comparisons. Evaluation must place the emphasis on quality and reliability. Several aspects should be thoroughly investigated and documented in the selection process. These include: personnel; equipment/facilities; procedures; and credentials

  12. Experience with the Ahmed Glaucoma Valve

    African Journals Online (AJOL)

    Design:Aprospective study of three glaucoma patients who had the Ahmed glaucoma valve implant at the. University of Benin ... Key words: glaucoma, glaucoma valve implant, ... introduced the micro-trephination with a diameter of. 0.6mm in ...

  13. Transcatheter aortic valve replacement and vascular complications definitions.

    Science.gov (United States)

    Van Mieghem, Nicolas M; Généreux, Philippe; van der Boon, Robert M A; Kodali, Susheel; Head, Stuart; Williams, Matthew; Daneault, Benoit; Kappetein, Arie-Pieter; de Jaegere, Peter P; Leon, Martin B; Serruys, Patrick W

    2014-03-20

    Transcatheter aortic valve replacement (TAVR) requires large calibre catheters and is therefore associated with increased vascular complications. The aim of this study was to illustrate the impact of the different definitions of major vascular complications on their incidence and to underscore the importance of uniform reporting. We pooled dedicated databases of consecutive patients undergoing TAVR from two tertiary care facilities and looked for the incidence of major vascular complications using various previously reported definitions. The level of agreement (Kappa statistic) between the respective definitions and the Valve Academic Research Consortium (VARC) consensus definition of vascular complications was assessed. A total of 345 consecutive patients underwent transfemoral TAVR and were included in this analysis. A completely percutaneous access and closure technique was applied in 96% of cases. Arterial sheath size ranged between 18 and 24 Fr, the majority being 18 Fr (60%). Procedural success was reached in 94.5%. Depending on the definition used, major vascular complications occurred in 5.2-15.9% of patients. According to the VARC definitions, the rate of major and minor vascular complications was 9.0% and 9.6%, respectively. Major vascular complications according to VARC criteria demonstrated at least a substantial level of agreement with the SOURCE registry (k 0.80), the UK registry (k 0.82) the Italian registry (k 0.72) and "FRANCE" registry (k 0.70) definitions, compared to a moderate level of agreement with the definitions used in the German registry ( 0.47) and the 18 Fr Safety and Efficacy study (k 0.42). Minor complications according to VARC demonstrated a moderate agreement only with vascular complications using the German registry definition (k 0.54). Non-uniformity in how vascular complications are defined precludes any reliable comparison between previously reported TAVR registries. The VARC consensus document offers standardised endpoint

  14. Leaving Moderate Tricuspid Valve Regurgitation Alone at the Time of Pulmonary Valve Replacement: A Worthwhile Approach.

    Science.gov (United States)

    Kogon, Brian; Mori, Makoto; Alsoufi, Bahaaldin; Kanter, Kirk; Oster, Matt

    2015-06-01

    Pulmonary valve disruption in patients with tetralogy of Fallot and congenital pulmonary stenosis often results in pulmonary insufficiency, right ventricular dilation, and tricuspid valve regurgitation. Management of functional tricuspid regurgitation at the time of subsequent pulmonary valve replacement remains controversial. Our aims were to (1) analyze tricuspid valve function after pulmonary valve replacement through midterm follow-up and (2) determine the benefits, if any, of concomitant tricuspid annuloplasty. Thirty-five patients with tetralogy of Fallot or congenital pulmonary stenosis were analyzed. All patients had been palliated in childhood by disrupting the pulmonary valve, and all patients had at least moderate tricuspid valve regurgitation at the time of subsequent pulmonary valve replacement. Preoperative and serial postoperative echocardiograms were analyzed. Pulmonary and tricuspid regurgitation, along with right ventricular dilation and dysfunction were scored as 0 (none), 1 (mild), 2 (moderate), and 3 (severe). Right ventricular volume and area were also calculated. Comparisons were made between patients who underwent pulmonary valve replacement alone and those who underwent concomitant tricuspid valve annuloplasty. At 1 month after pulmonary valve replacement, there were significant reductions in pulmonary valve regurgitation (mean 3 vs 0.39, p tricuspid valve regurgitation (mean 2.33 vs 1.3, p tricuspid regurgitation 1 month postoperatively between patients who underwent concomitant tricuspid annuloplasty and those who underwent pulmonary valve replacement alone (mean 1.31 vs 1.29, p = 0.81). However, at latest follow-up (mean 7.0 ± 2.8 years), the degree of tricuspid regurgitation was significantly higher in the concomitant annuloplasty group (mean 1.87 vs 1.12, p = 0.005). In patients with at least moderate tricuspid valve regurgitation, significant improvement in tricuspid valve function and right ventricular size occurs in the first

  15. Scalp Wound Closure with K wires: An alternative easier method to scalp wound closure.

    Science.gov (United States)

    Ramesh, S; Ajik, S

    2012-12-01

    Scalp defects and lacerations present a reconstructive challenge to plastic surgeons. Many methods have been described from the use of skin grafting to rotation flaps. Here we present a method of closure of a contaminated scalp wound with the use of Kirschner wires. In our case, closure of scalp laceration was made possible with the use of 1.4 Kirschner wires and cable tie/ zip tie fasteners. The duration to closure of wound was 10 days. In reconstructing the scalp defect, this method was found to adhere to principles of scalp reconstruction. There were no post operative complications found from the procedure. On initial application on the edge of the wound, tension applied caused the K wires to cut through the wound edge. On replacement of K wires 1cm away from wound edge the procedure was not plagued by any further complication. In conclusion we find scalp closure with Kirschner wires are a simple and effective method for scalp wound closure.

  16. Aortic Root Enlargement or Sutureless Valve Implantation?

    Directory of Open Access Journals (Sweden)

    Nikolaos G. Baikoussis

    2016-11-01

    Full Text Available Aortic valve replacement (AVR in patients with a small aortic annulus is a challenging issue. The importance of prosthesis–patient mismatch (PPM post aortic valve replacement (AVR is controversial but has to be avoided. Many studies support the fact that PPM has a negative impact on short and long term survival. In order to avoid PPM, aortic root enlargement may be performed. Alternatively and keeping in mind that often some comorbidities are present in old patients with small aortic root, the Perceval S suturelles valve implantation could be a perfect solution. The Perceval sutureless bioprosthesis provides reasonable hemodynamic performance avoiding the PPM and providing the maximum of aortic orifice area. We would like to see in the near future the role of the aortic root enlargement techniques in the era of surgical implantation of the sutureless valve (SAVR and the transcatheter valve implantation (TAVI.

  17. Transcatheter Mitral Valve Devices - Functional Mechanical Designs.

    Science.gov (United States)

    Kliger, Chad

    2014-03-01

    Mitral regurgitation is a complex disorder involving a multitude of components of the mitral apparatus. With the desire for less invasive treatment approaches, transcatheter mitral valve therapies (TMVT) are directed at these components and available at varying stages of development. Therapeutic advancements and the potential to combine technologies may further improve their efficacy and safety. Transcatheter mitral valve replacement, while preserving the mitral apparatus, may emerge as an alternative or even a more suitable treatment option. In addition, early data on transcatheter mitral valve-in-valve and valve-in-ring implantation are encouraging and this approach may be an alternative to reoperation in the high-risk patient. This review details the expanding functional mechanical designs of current active TMVT.

  18. Stomal Closure: Strategies to Prevent Incisional Hernia

    Science.gov (United States)

    Harries, Rhiannon L.; Torkington, Jared

    2018-01-01

    Incisional hernias following ostomy reversal occur frequently. Incisional hernias at the site of a previous stoma closure can cause significant morbidity, impaired quality of life, lead to life-threatening hernia incarceration or strangulation and result in a significant financial burden on health care systems Despite this, the evidence base on the subject is limited. Many recognised risk factors for the development of incisional hernia following ostomy reversal are related to patient factors such as age, malignancy, diabetes, COPD, hypertension and obesity, and are not easily correctable. There is a limited amount of evidence to suggest that prophylactic mesh reinforcement may be of benefit to reduce the post stoma closure incisional hernia rate but a further large scale randomised controlled trial is due to report in the near future. There appears to be weak evidence to suggest that surgeons should favour circular, or “purse-string” closure of the skin following stoma closure in order to reduce the risk of SSI, which in turn may reduce incisional hernia formation. There remains the need for further evidence in relation to suture technique, skin closure techniques, mechanical bowel preparation and oral antibiotic prescription focusing on incisional hernia development as an outcome measure. Within this review, we discuss in detail the evidence base for the risk factors for the development of, and the strategies to prevent ostomy reversal site incisional hernias. PMID:29670882

  19. Angle closure glaucoma in congenital ectropion uvea

    Directory of Open Access Journals (Sweden)

    Grace M. Wang

    2018-06-01

    Full Text Available Purpose: Congenital ectropion uvea is a rare anomaly, which is associated with open, but dysplastic iridocorneal angles that cause childhood glaucoma. Herein, we present 3 cases of angle-closure glaucoma in children with congenital ectropion uvea. Observations: Three children were initially diagnosed with unilateral glaucoma secondary to congenital ectropion uvea at 7, 8 and 13 years of age. The three cases showed 360° of ectropion uvea and iris stromal atrophy in the affected eye. In one case, we have photographic documentation of progression to complete angle closure, which necessitated placement of a glaucoma drainage device 3 years after combined trabeculotomy and trabeculectomy. The 2 other cases, which presented as complete angle closure, also underwent glaucoma drainage device implantation. All three cases had early glaucoma drainage device encapsulation (within 4 months and required additional surgery (cycloablation or trabeculectomy. Conclusions and importance: Congenital ectropion uvea can be associated with angle-closure glaucoma, and placement of glaucoma drainage devices in all 3 of our cases showed early failure due to plate encapsulation. Glaucoma in congenital ectropion uvea requires attention to angle configuration and often requires multiple surgeries to obtain intraocular pressure control. Keywords: Congenital ectropion uvea, Juvenile glaucoma, Angle-closure glaucoma, Glaucoma drainage device

  20. Closure of shallow underground injection wells

    International Nuclear Information System (INIS)

    Veil, J.A.; Grunewald, B.

    1993-01-01

    Shallow injection wells have long been used for disposing liquid wastes. Some of these wells have received hazardous or radioactive wastes. According to US Environmental Protection Agency (EPA) regulations, Class IV wells are those injection wells through which hazardous or radioactive wastes are injected into or above an underground source of drinking water (USDW). These wells must be closed. Generally Class V wells are injection wells through which fluids that do not contain hazardous or radioactive wastes are injected into or above a USDW. Class V wells that are responsible for violations of drinking water regulations or that pose a threat to human health must also be closed. Although EPA regulations require closure of certain types of shallow injection wells, they do not provide specific details on the closure process. This paper describes the regulatory background, DOE requirements, and the steps in a shallow injection well closure process: Identification of wells needing closure; monitoring and disposal of accumulated substances; filling and sealing of wells; and remediation. In addition, the paper describes a major national EPA shallow injection well enforcement initiative, including closure plan guidance for wells used to dispose of wastes from service station operations

  1. Stomal Closure: Strategies to Prevent Incisional Hernia

    Directory of Open Access Journals (Sweden)

    Rhiannon L. Harries

    2018-04-01

    Full Text Available Incisional hernias following ostomy reversal occur frequently. Incisional hernias at the site of a previous stoma closure can cause significant morbidity, impaired quality of life, lead to life-threatening hernia incarceration or strangulation and result in a significant financial burden on health care systems Despite this, the evidence base on the subject is limited. Many recognised risk factors for the development of incisional hernia following ostomy reversal are related to patient factors such as age, malignancy, diabetes, COPD, hypertension and obesity, and are not easily correctable. There is a limited amount of evidence to suggest that prophylactic mesh reinforcement may be of benefit to reduce the post stoma closure incisional hernia rate but a further large scale randomised controlled trial is due to report in the near future. There appears to be weak evidence to suggest that surgeons should favour circular, or “purse-string” closure of the skin following stoma closure in order to reduce the risk of SSI, which in turn may reduce incisional hernia formation. There remains the need for further evidence in relation to suture technique, skin closure techniques, mechanical bowel preparation and oral antibiotic prescription focusing on incisional hernia development as an outcome measure. Within this review, we discuss in detail the evidence base for the risk factors for the development of, and the strategies to prevent ostomy reversal site incisional hernias.

  2. Glued structural members

    Science.gov (United States)

    Russell C. Moody; Jen Y. Liu

    1999-01-01

    Glued structural members are manufactured in a variety of configurations. Structural composite lumber (SCL) products consist of small pieces of wood glued together into sizes common for solid-sawn lumber. Glued-laminated timber (glulam) is an engineered stress-rated product that consists of two or more layers of lumber in which the grain of all layers is oriented...

  3. CERN welcomes new members

    Science.gov (United States)

    2017-08-01

    Lithuania is on course to become an associate member of CERN, pending final approval by the Lithuanian parliament. Associate membership will allow representatives of the Baltic nation to take part in meetings of the CERN Council, which oversees the Geneva-based physics lab.

  4. DUBNA: Member States

    International Nuclear Information System (INIS)

    Anon.

    1992-01-01

    The political upheaval in what was the Soviet Union was reflected in an Extraordinary Plenipotentiaries Committee of Joint Institute for Nuclear Research (JINR) Member States, held in Dubna, near Moscow, on 10-13 December, with representatives of eleven sovereign republics of the former Soviet State taking part

  5. AREVA's innovative solutions for valve diagnostics and in-situ valve repair

    International Nuclear Information System (INIS)

    Damies, H.; Breitenberger, U.; Munoz, L.; Kostroun, F.

    2012-01-01

    Optimized maintenance strategies are a key aspect for safe and undisturbed plant operation. Innovative valve service solutions can support that in an efficient way. The ADAM®/SIPLUG® valve monitoring system allows full online monitoring of valves and actuators with automatic evaluation and assessment. Especially for safety-related and operation-related valves this provides valuable information on components condition to ensure proper function and contribute to optimization of maintenance strategies as well as effective maintenance performance. More than 25 years of experience in various plants worldwide show that application of ADAM®/SIPLUG® valve diagnostics solution leads to increased plant safety and availability. With the innovative AVARIS technology an in-situ valve repair is possible. It has the unique ability to conduct several steps in-situ, to maintain the sealing seat of gate or check valves. By applying AVARIS, the valve is restored in its original state, the system remains unchanged. Thus, all original documents remain valid and applicable. In comparison to previous procedures like cutting valves out of the pipeline and repairing hard facings or damaged seal seats in a separate workshop or alternatively replacement by a new valve body the new AVARIS technology avoids costs, risk and effort. (author)

  6. Use of a valve operation test and evaluation system to enhance valve reliability

    International Nuclear Information System (INIS)

    Lowry, D.A.

    1990-01-01

    Power plant owners have emphasized the need for assuring safe, reliable operation of valves. While most valves must simply open or close, the mechanisms involved can be quite complex. Motor operated valves (MOVs) must be properly adjusted to assure operability. Individual operator components determine the performance of the entire MOV. Failure in MOVs could cripple or shut down a unit. Thus, a complete valve program consisting of design reviews, operational testing, and preventive and predictive maintenance activities will enhance an owner's confidence level that his valves win operate as expected. Liberty's Valve Operation Test and Evaluation System (VOTES) accurately measures stein thrust without intruding on valve operation. Since mounting a strain gage to a valve stem is a desirable but impractical way of obtaining precise stem thrust, Liberty developed a method to obtain identical data by placing a strain gage sensor on the valve yoke. VOTES provides information which effectively eliminates costly, unscheduled downtime. This paper presents the results of infield VOTES testing. The system's proven ability to identify and characterize actuator and valve performance is demonstrated. Specific topics of discussion include the ability of VOTES to ease a utility's IE Bulletin 8543 concerns and conclusively diagnose MOV components. Data from static and differential pressure testing are presented. Technical, operational, and financial advantages resulting from VOTES technology are explored in detail

  7. Biological constraints do not entail cognitive closure.

    Science.gov (United States)

    Vlerick, Michael

    2014-12-01

    From the premise that our biology imposes cognitive constraints on our epistemic activities, a series of prominent authors--most notably Fodor, Chomsky and McGinn--have argued that we are cognitively closed to certain aspects and properties of the world. Cognitive constraints, they argue, entail cognitive closure. I argue that this is not the case. More precisely, I detect two unwarranted conflations at the core of arguments deriving closure from constraints. The first is a conflation of what I will refer to as 'representation' and 'object of representation'. The second confuses the cognitive scope of the assisted mind for that of the unassisted mind. Cognitive closure, I conclude, cannot be established from pointing out the (uncontroversial) existence of cognitive constraints. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Hanford Patrol Academy demolition sites closure plan

    Energy Technology Data Exchange (ETDEWEB)

    1993-09-30

    The Hanford Site is owned by the U.S. Government and operated by the U.S. Department of Energy, Richland Operations Office. Westinghouse Hanford Company is a major contractor to the U.S. Department of Energy, Richland Operations Office and serves as co-operator of the Hanford Patrol Academy Demolition Sites, the unit addressed in this paper. This document consists of a Hanford Facility Dangerous Waste Part A Permit Application, Form 3 (Revision 4), and a closure plan for the site. An explanation of the Part A Form 3 submitted with this closure plan is provided at the beginning of the Part A section. This Hanford Patrol Academy Demolition Sites Closure Plan submittal contains information current as of December 15, 1994.

  9. Development of an arid site closure plan

    International Nuclear Information System (INIS)

    Nyhan, J.W.; Barnes, F.J.

    1987-01-01

    This document describes the development of a prototype plan for the effective closure and stabilization of an arid low-level waste disposal site. This plan will provide demonstrated closure techniques for a trench in a disposal site at Los Alamos. The accuracy of modeling soil water storage by two hydrologic models, CREAMS and HELP, was tested by comparing simulation results with field measurements of soil moisture in eight experimental landfill cover systems having a range of well-defined soil profiles and vegetative covers. Regression analysis showed that CREAMS generally represented soil moisture more accurately than HELP simulations. Precautions for determining parameter values for model input and for interpreting simulation results are discussed. A specific example is presented showing how the field-validated hydrologic models can be used to develop a final prototype closure plan. 15 refs., 13 figs., 3 tabs

  10. Primary closure of equine laryngotomy incisions

    DEFF Research Database (Denmark)

    Lindegaard, C.; Karlsson, L.; Ekstrøm, Claus Thorn

    2016-01-01

    incision between January 1995 and June 2012 were reviewed. Horses with a laryngotomy incision closed in three layers for primary healing were included. Descriptive data on healing characteristics and complications of laryngotomy wounds were collected from the medical records and via follow......The objective was to report healing characteristics and complications after primary closure of equine laryngotomies and analyse factors potentially associated with complications. This retrospective case series of the medical records of horses (n = 180) undergoing laryngoplasty and laryngotomy...... after primary closure of equine laryngotomy incisions are infrequent and considered of minimal severity and can be performed safely when paying careful attention to the closure of the cricothyroid membrane....

  11. THE RESULTS OF SURGICAL TREATMENT OF TRICUSPID VALVE INFECTIVE ENDOCARDITIS USING VALVE REPAIR AND VALVE REPLACEMENT OPERATIONS

    Directory of Open Access Journals (Sweden)

    S. A. Kovalev

    2015-01-01

    Full Text Available Aim. To evaluate in-hospital and long-term results of surgical treatment of patients with infective endocarditis of the tricuspid valve, to compare the effectiveness of valve repair and valve replacement techniques, and to identify risk factors of mortality and reoperations. Materials and methods. 31 surgical patients with tricuspid valve infective endocarditis were evaluated. Patients were divided into 2 groups. In Group 1 (n = 14 repairs of the tricuspid valve were performed, in Group 2 (n = 17 patients had undergone tricuspid valve replacements. Epidemiological, clinical, microbiological and echocardiographic data were studied. Methods of comparative analysis, the Kaplan–Meier method, and Cox risk models were applied. Results. The most common complication of in-hospital stay was atrioventricular block (17.7% of cases in Group 2. In Group 1, this type of complication was not found. Hospital mortality was 7.14% in Group 1, and 0% in Group 2. Long-term results have shown the significant reduction of heart failure in general cohort and in both groups. In Group 1 the severity of heart failure in the long term was less than in Group 2. No significant differences in the severity of tricuspid regurgitation were found between the groups. In 7-year follow up no cases of death were registered in Group 1. Cumulative survival rate in Group 2 within 60 months was 67.3 ± 16.2%. No reoperations were performed in patients from Group 1. In Group 2, the freedom from reoperation within 60 months was 70.9 ± 15.3%. Combined intervention was found as predictor of postoperative mortality. Prosthetic valve endocarditis was identified as risk factor for reoperation. Conclusion. Valve repair and valve replacement techniques of surgical treatment of tricuspid valve endocarditis can provide satisfactory hospital and long-term results. Tricuspid valve repair techniques allowed reducing the incidence of postoperative atrioventricular block. In the long-term, patients

  12. Functional property of the cardiac valve prosthesis evaluated in vivo by cine-radiography

    Energy Technology Data Exchange (ETDEWEB)

    Murakoshi, Sadaaki

    1986-07-01

    Functional property of the convexo-concave Bjoerk-Shiley cardiac valve prosthesis implanted in the mitral position of 21 patients was investigated by integrated cine-radiography repeated for a long term after operation. The maximum opening angle of the tilting disc was 58 +- 2 deg, and was not affected by atrial fibrillation nor by tachycardia up to 160 bpm. There was no change in the maximum opening angle of the disc observed during follow-up period. Good correlation between shortning of the disc opening time and increase in pulse rate suggests excellent adaptation of this prosthesis for tachycardia induced by exercise or electric pacing. However, atrial fibrillation causes time delay in disc closure immediately after prolonged R-R interval. Disc rotation alleviating disc wear was observed in all the patients whether it moves slow or quick. Dysfunction of the disc opening can be readily determined not only by measuring the maximum disc opening angle, but also by observing the characteristic movement indicated in this study. It is concluded from these results that clinical apprication for the convexo-concave Bjoerk-Shiley valve prosthesis is appropriate and cine-radiography is an useful non-invasive examination of cardiac valve prosthesis for long follow-up period.

  13. Functional property of the cardiac valve prosthesis evaluated in vivo by cine-radiography

    International Nuclear Information System (INIS)

    Murakoshi, Sadaaki

    1986-01-01

    Functional property of the convexo-concave Bjoerk-Shiley cardiac valve prosthesis implanted in the mitral position of 21 patients was investigated by integrated cine-radiography repeated for a long term after operation. The maximum opening angle of the tilting disc was 58 ± 2 deg, and was not affected by atrial fibrillation nor by tachycardia up to 160 bpm. There was no change in the maximum opening angle of the disc observed during follow-up period. Good correlation between shortning of the disc opening time and increase in pulse rate suggests excellent adaptation of this prosthesis for tachycardia induced by exercise or electric pacing. However, atrial fibrillation causes time delay in disc closure immediately after prolonged R-R interval. Disc rotation alleviating disc wear was observed in all the patients whether it moves slow or quick. Dysfunction of the disc opening can be readily determined not only by measuring the maximum disc opening angle, but also by observing the characteristic movement indicated in this study. It is concluded from these results that clinical apprication for the convexo-concave Bjoerk-Shiley valve prosthesis is appropriate and cine-radiography is an useful non-invasive examination of cardiac valve prosthesis for long follow-up period. (author)

  14. Hamiltonian closures in fluid models for plasmas

    Science.gov (United States)

    Tassi, Emanuele

    2017-11-01

    This article reviews recent activity on the Hamiltonian formulation of fluid models for plasmas in the non-dissipative limit, with emphasis on the relations between the fluid closures adopted for the different models and the Hamiltonian structures. The review focuses on results obtained during the last decade, but a few classical results are also described, in order to illustrate connections with the most recent developments. With the hope of making the review accessible not only to specialists in the field, an introduction to the mathematical tools applied in the Hamiltonian formalism for continuum models is provided. Subsequently, we review the Hamiltonian formulation of models based on the magnetohydrodynamics description, including those based on the adiabatic and double adiabatic closure. It is shown how Dirac's theory of constrained Hamiltonian systems can be applied to impose the incompressibility closure on a magnetohydrodynamic model and how an extended version of barotropic magnetohydrodynamics, accounting for two-fluid effects, is amenable to a Hamiltonian formulation. Hamiltonian reduced fluid models, valid in the presence of a strong magnetic field, are also reviewed. In particular, reduced magnetohydrodynamics and models assuming cold ions and different closures for the electron fluid are discussed. Hamiltonian models relaxing the cold-ion assumption are then introduced. These include models where finite Larmor radius effects are added by means of the gyromap technique, and gyrofluid models. Numerical simulations of Hamiltonian reduced fluid models investigating the phenomenon of magnetic reconnection are illustrated. The last part of the review concerns recent results based on the derivation of closures preserving a Hamiltonian structure, based on the Hamiltonian structure of parent kinetic models. Identification of such closures for fluid models derived from kinetic systems based on the Vlasov and drift-kinetic equations are presented, and

  15. A kinematic view of loop closure.

    Science.gov (United States)

    Coutsias, Evangelos A; Seok, Chaok; Jacobson, Matthew P; Dill, Ken A

    2004-03-01

    We consider the problem of loop closure, i.e., of finding the ensemble of possible backbone structures of a chain segment of a protein molecule that is geometrically consistent with preceding and following parts of the chain whose structures are given. We reduce this problem of determining the loop conformations of six torsions to finding the real roots of a 16th degree polynomial in one variable, based on the robotics literature on the kinematics of the equivalent rotator linkage in the most general case of oblique rotators. We provide a simple intuitive view and derivation of the polynomial for the case in which each of the three pair of torsional axes has a common point. Our method generalizes previous work on analytical loop closure in that the torsion angles need not be consecutive, and any rigid intervening segments are allowed between the free torsions. Our approach also allows for a small degree of flexibility in the bond angles and the peptide torsion angles; this substantially enlarges the space of solvable configurations as is demonstrated by an application of the method to the modeling of cyclic pentapeptides. We give further applications to two important problems. First, we show that this analytical loop closure algorithm can be efficiently combined with an existing loop-construction algorithm to sample loops longer than three residues. Second, we show that Monte Carlo minimization is made severalfold more efficient by employing the local moves generated by the loop closure algorithm, when applied to the global minimization of an eight-residue loop. Our loop closure algorithm is freely available at http://dillgroup. ucsf.edu/loop_closure/. Copyright 2004 Wiley Periodicals, Inc. J Comput Chem 25: 510-528, 2004

  16. Reactor vessel closure head replacements in 1997

    International Nuclear Information System (INIS)

    Anon.

    1997-01-01

    The Framatome-Jeumont Industrie consortium have completed in 1997 28 reactor vessel (RV) closure head replacements, including five on 1300 MWe class PWR units. Framatome manages the operations and handles removal and reinstallation of equipment (not including the control rod drive mechanisms (CRDM)) and the requalification tests, while JI, which manufactures the CRDMs, is involved in the CRDM cutting, re-machining and welding operations, using tools of original design, in order to optimize the RV closure head operation in terms of costs, schedule and dosage

  17. Closure properties of Watson-Crick grammars

    Science.gov (United States)

    Zulkufli, Nurul Liyana binti Mohamad; Turaev, Sherzod; Tamrin, Mohd Izzuddin Mohd; Azeddine, Messikh

    2015-12-01

    In this paper, we define Watson-Crick context-free grammars, as an extension of Watson-Crick regular grammars and Watson-Crick linear grammars with context-free grammar rules. We show the relation of Watson-Crick (regular and linear) grammars to the sticker systems, and study some of the important closure properties of the Watson-Crick grammars. We establish that the Watson-Crick regular grammars are closed under almost all of the main closure operations, while the differences between other Watson-Crick grammars with their corresponding Chomsky grammars depend on the computational power of the Watson-Crick grammars which still need to be studied.

  18. Straight line closure of congenital macrostomia

    Directory of Open Access Journals (Sweden)

    Schwarz Richard

    2004-01-01

    Full Text Available The results of patients operated on by Nepal Cleft Lip and Palate Association (NECLAPA surgeons for congenital macrostomia were prospectively studied between January 2000 and December 2002. There were four males and three females with a median age of 10 years. Three had an associated branchial arch syndrome. In all patients an overlapping repair of orbicularis oris was done. Six patients had a straight line closure with excellent cosmetic results and one a Z-plasty with a more obvious scar. All had a normal appearing commissure. Overlapping orbicularis repair with straight line skin closure for this rare congenital anomaly is recommended.

  19. Environmental considerations in mine closure planning

    International Nuclear Information System (INIS)

    Ricks, G.

    1997-01-01

    Mine closure planning considers the best ways to plan and manage the environmental changes and socio-economic effects associated with the closing of mines. While the criteria for judging successful closures may vary, it is particularly important for physical, chemical and biological stability to be achieved and for final land use to be appropriate. Trust funds are increasingly favoured as a practical means of fulfilling the requirement for a financial surety and of ensuring that financial provision is available at the end of the mine's life. (author)

  20. Uncertainty Quantification of Multi-Phase Closures

    Energy Technology Data Exchange (ETDEWEB)

    Nadiga, Balasubramanya T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Baglietto, Emilio [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2017-10-27

    In the ensemble-averaged dispersed phase formulation used for CFD of multiphase ows in nuclear reactor thermohydraulics, closures of interphase transfer of mass, momentum, and energy constitute, by far, the biggest source of error and uncertainty. Reliable estimators of this source of error and uncertainty are currently non-existent. Here, we report on how modern Validation and Uncertainty Quanti cation (VUQ) techniques can be leveraged to not only quantify such errors and uncertainties, but also to uncover (unintended) interactions between closures of di erent phenomena. As such this approach serves as a valuable aide in the research and development of multiphase closures. The joint modeling of lift, drag, wall lubrication, and turbulent dispersion|forces that lead to tranfer of momentum between the liquid and gas phases|is examined in the frame- work of validation of the adiabatic but turbulent experiments of Liu and Banko , 1993. An extensive calibration study is undertaken with a popular combination of closure relations and the popular k-ϵ turbulence model in a Bayesian framework. When a wide range of super cial liquid and gas velocities and void fractions is considered, it is found that this set of closures can be validated against the experimental data only by allowing large variations in the coe cients associated with the closures. We argue that such an extent of variation is a measure of uncertainty induced by the chosen set of closures. We also nd that while mean uid velocity and void fraction pro les are properly t, uctuating uid velocity may or may not be properly t. This aspect needs to be investigated further. The popular set of closures considered contains ad-hoc components and are undesirable from a predictive modeling point of view. Consequently, we next consider improvements that are being developed by the MIT group under CASL and which remove the ad-hoc elements. We use non-intrusive methodologies for sensitivity analysis and calibration (using

  1. Laser peripheral iridoplasty for angle-closure.

    Science.gov (United States)

    Ng, Wai Siene; Ang, Ghee Soon; Azuara-Blanco, Augusto

    2012-02-15

    Angle-closure glaucoma is a leading cause of irreversible blindness in the world. Treatment is aimed at opening the anterior chamber angle and lowering the IOP with medical and/or surgical treatment (e.g. trabeculectomy, lens extraction). Laser iridotomy works by eliminating pupillary block and widens the anterior chamber angle in the majority of patients. When laser iridotomy fails to open the anterior chamber angle, laser iridoplasty may be recommended as one of the options in current standard treatment for angle-closure. Laser peripheral iridoplasty works by shrinking and pulling the peripheral iris tissue away from the trabecular meshwork. Laser peripheral iridoplasty can be used for crisis of acute angle-closure and also in non-acute situations.   To assess the effectiveness of laser peripheral iridoplasty in the treatment of narrow angles (i.e. primary angle-closure suspect), primary angle-closure (PAC) or primary angle-closure glaucoma (PACG) in non-acute situations when compared with any other intervention. In this review, angle-closure will refer to patients with narrow angles (PACs), PAC and PACG. We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2011, Issue 12), MEDLINE (January 1950 to January 2012), EMBASE (January 1980 to January 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to January 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). There were no date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 5 January 2012. We included only randomised controlled trials (RCTs) in this review. Patients with narrow angles, PAC or PACG were eligible. We excluded studies that included only patients with acute presentations

  2. Special closure for radioactive shipping container

    International Nuclear Information System (INIS)

    Otts, J.V.

    1976-03-01

    The objective of this program was to develop a special lid closure for radioactive material shipping containers, typically steel drums. Three closure techniques were designed, fabricated, and proven to be structurally adequate to protect 1000 lb when dropped 30 ft. The three designs were (1) a 6-in. lid extension (skirt), (2) a 6-in. inner lid, and (3) c-clamps used at the container/lid interface. Based upon structural integrity, economic impact, and minimal design change, the 6-in. lid extension is recommended

  3. Valve packing manual. A maintenance application guide

    International Nuclear Information System (INIS)

    Aikin, J.A.; McCutcheon, R.G.; Cumming, D.

    1997-01-01

    Since 1970, AECL Chalk River Mechanical Equipment Development (MED) branch has invested over 175 person years in testing related to improving valve packing performance. Successful developments, including, 'live-loading', reduced packing heights, and performance-based packing qualification testing have been implemented. Since 1986, MED and the Integrated Valve Actuator Program Task Force - Valve Packing Steering Committee (IVAP-VPSC) have been involved in the development of combination die-formed graphite packing for use in CANDU plants. Many reports, articles, and specifications have been issued. Due to the large amount of test data and reports, a more user-friendly document has been prepared for everyday use. The Valve Packing Manual is based on many years of MED research and testing, as well as operating experience from CANDU nuclear generating stations (NGS). Since 1986, packing research and testing has been funded by the CANDU Owners Group (COG), the Electric Power Research Institute (EPRI), and participating valve packing manufacturers. The Valve Packing Manual (VPM) provides topical summaries of all work related to valve packing done since 1985. It includes advances in configuration design, stem packing friction, materials specifications, and installation procedures. This paper provides an overview on the application of the VPM with a focus on qualification testing, packing configuration, and stem packing friction. (author)

  4. Environmental qualification testing of TFE valve components

    International Nuclear Information System (INIS)

    Eyvindson, A.; Krasinski, W.; McCutcheon, R.

    1997-01-01

    Valves containing tetrafluoroethylene (TFE) components are being used in many CANDU Nuclear Generating Stations. However, some concerns remain about the performance of TFE after exposure to high levels of radiation. Stations must therefore ensure that such valves perform reliably after being exposed to postulated accident radiation dose levels. The current Ontario Hydro Environmental Qualification [EQ] program specifies much higher postulated radiation exposure than the original design, to account for conditions following a LOCA. Initial assessments indicated that Teflon components would require replacement. Proof of acceptable performance can remove the need for large scale replacement, avoiding a significant cost penalty and preserving benefits due to the superior performance of TFE-based seals. A test program was undertaken at Chalk River Laboratories (CRL) to investigate the performance of three valves after irradiation to 10 Mrad. Such valves are currently used at the Bruce B Nuclear Generating Station. Each contains TFE packing rings; one also has TFE seats. Two of the valves are used in the ECIS recovery system, while the third is used for instrumentation loop isolation or as drain valves. All are exposed to little or no radiation during normal use. Based on the results of the tests, all the valves tested will still meet functional and performance requirements after the TFE components have been exposed to 10 Mrad of irradiation. (author)

  5. Motor operated valves problems tests and simulations

    Energy Technology Data Exchange (ETDEWEB)

    Pinier, D.; Haas, J.L.

    1996-12-01

    An analysis of the two refusals of operation of the EAS recirculation shutoff valves enabled two distinct problems to be identified on the motorized valves: the calculation methods for the operating torques of valves in use in the power plants are not conservative enough, which results in the misadjustement of the torque limiters installed on their motorizations, the second problem concerns the pressure locking phenomenon: a number of valves may entrap a pressure exceeding the in-line pressure between the disks, which may cause a jamming of the valve. EDF has made the following approach to settle the first problem: determination of the friction coefficients and the efficiency of the valve and its actuator through general and specific tests and models, definition of a new calculation method. In order to solve the second problem, EDF has made the following operations: identification of the valves whose technology enables the pressure to be entrapped: the tests and numerical simulations carried out in the Research and Development Division confirm the possibility of a {open_quotes}boiler{close_quotes} effect: determination of the necessary modifications: development and testing of anti-boiler effect systems.

  6. Hardfacing and packings for improved valve performance

    International Nuclear Information System (INIS)

    Aikin, J.A.; Patrick, J.N.F.; Inglis, I.

    2003-01-01

    The CANDU Owners Group (COG), Chemistry, Materials and Components (CMC) Program has supported an ongoing program on valve maintenance and performance for several years. An overview is presented of recent work on iron-based hardfacing, packing qualification, friction testing of polytetrafluoroethylene (PTFE) packings, and an investigation of re-torquing valve packing. Based on this program, two new valve-packing materials have been qualified for use in CANDU stations. By doing this, CANDU maintenance can avoid having only one packing qualified for station use, as well as assess the potential impact of the industry trend towards using lower gland loads. The results from corrosion tests by AECL and the coefficient of friction studies at Battelle' s tribology testing facilities on Delcrome 910, an iron-based hardfacing alloy, indicate it is an acceptable replacement for Stellite 6 under certain conditions. This information can be used to update in-line valve purchasing specifications. The renewed interest in friction characteristics, and environmental qualification (EQ) of packing containing PTFE has resulted in a new test program in these areas. The COG-funded valve programs have resulted in modifications to design specifications for nuclear station in-line valves and have led to better maintenance practices and valve reliability. In the end, this means lower costs and cheaper electricity. (author)

  7. Echocardiographic Assessment of Heart Valve Prostheses

    Science.gov (United States)

    Sordelli, Chiara; Severino, Sergio; Ascione, Luigi; Coppolino, Pasquale; Caso, Pio

    2014-01-01

    Patients submitted to valve replacement with mechanical or biological prosthesis, may present symptoms related either to valvular malfunction or ventricular dysfunction from other causes. Because a clinical examination is not sufficient to evaluate a prosthetic valve, several diagnostic methods have been proposed to assess the functional status of a prosthetic valve. This review provides an overview of echocardiographic and Doppler techniques useful in evaluation of prosthetic heart valves. Compared to native valves, echocardiographic evaluation of prosthetic valves is certainly more complex, both for the examination and the interpretation. Echocardiography also allows discriminating between intra- and/or peri-prosthetic regurgitation, present in the majority of mechanical valves. Transthoracic echocardiography (TTE) requires different angles of the probe with unconventional views. Transesophageal echocardiography (TEE) is the method of choice in presence of technical difficulties. Three-dimensional (3D)-TEE seems to be superior to 2D-TEE, especially in the assessment of paravalvular leak regurgitation (PVL) that it provides improved localization and analysis of the PVL size and shape. PMID:28465917

  8. Magnon Valve Effect between Two Magnetic Insulators

    Science.gov (United States)

    Wu, H.; Huang, L.; Fang, C.; Yang, B. S.; Wan, C. H.; Yu, G. Q.; Feng, J. F.; Wei, H. X.; Han, X. F.

    2018-03-01

    The key physics of the spin valve involves spin-polarized conduction electrons propagating between two magnetic layers such that the device conductance is controlled by the relative magnetization orientation of two magnetic layers. Here, we report the effect of a magnon valve which is made of two ferromagnetic insulators (YIG) separated by a nonmagnetic spacer layer (Au). When a thermal gradient is applied perpendicular to the layers, the inverse spin Hall voltage output detected by a Pt bar placed on top of the magnon valve depends on the relative orientation of the magnetization of two YIG layers, indicating the magnon current induced by the spin Seebeck effect at one layer affects the magnon current in the other layer separated by Au. We interpret the magnon valve effect by the angular momentum conversion and propagation between magnons in two YIG layers and conduction electrons in the Au layer. The temperature dependence of the magnon valve ratio shows approximately a power law, supporting the above magnon-electron spin conversion mechanism. This work opens a new class of valve structures beyond the conventional spin valves.

  9. Motor operated valves problems tests and simulations

    International Nuclear Information System (INIS)

    Pinier, D.; Haas, J.L.

    1996-01-01

    An analysis of the two refusals of operation of the EAS recirculation shutoff valves enabled two distinct problems to be identified on the motorized valves: the calculation methods for the operating torques of valves in use in the power plants are not conservative enough, which results in the misadjustement of the torque limiters installed on their motorizations, the second problem concerns the pressure locking phenomenon: a number of valves may entrap a pressure exceeding the in-line pressure between the disks, which may cause a jamming of the valve. EDF has made the following approach to settle the first problem: determination of the friction coefficients and the efficiency of the valve and its actuator through general and specific tests and models, definition of a new calculation method. In order to solve the second problem, EDF has made the following operations: identification of the valves whose technology enables the pressure to be entrapped: the tests and numerical simulations carried out in the Research and Development Division confirm the possibility of a open-quotes boilerclose quotes effect: determination of the necessary modifications: development and testing of anti-boiler effect systems

  10. Flowfield Analysis of a Pneumatic Solenoid Valve

    Directory of Open Access Journals (Sweden)

    Sheam-Chyun Lin

    2018-07-01

    Full Text Available Pneumatic solenoid valve has been widely used in the vehicle control systems for meeting the rapid-reaction demand triggered by the dynamic conditions encountered during the driving course of vehicle. For ensuring the safety of human being, the reliable and effective solenoid valve is in great demand to shorten the reaction time and thus becomes the topic of this research. This numerical study chooses a commercial 3/2-way solenoid valve as the reference valve for analysing its performance. At first, CFD software Fluent is adopted to simulate the flow field associated with the valve configuration. Then, the comprehensive flow visualization is implemented to identify the locations of adverse flow patterns. Accordingly, it is found that a high-pressure region exists in the zone between the nozzle exit and the top of iron core. Thereafter, the nozzle diameter and the distance between nozzle and spool are identified as the important design parameters for improving the pressure response characteristics of valve. In conclusion, this work establishes a rigorous and systematic CFD scheme to evaluate the performance of pneumatic solenoid valve.

  11. Supporting Members and Friends

    Science.gov (United States)

    2005-10-01

    Thank you! Over the past year, AGU has received 12,104 gifts, both large and small, from members and friends. The Union has also received corporate contributions, National Science Foundation grants, and support from the National Oceanographic Partnership Program and National Association of Geoscience Teachers. Together their generosity has benefited AGU non revenue producing programs that are critical to our science and the future health of the Union. The following list gratefully acknowledges annual gifts of $100 or more and cumulative giving of $5,000 or more. The 1919 Society ($100,000 or more) and Benefactors ($5,000-$99,999) recognize single major gifts and cumulative contributions. Three circles acknowledge annual giving: President's Circle ($1,000 or more), Leadership Circle ($200-$999), and Supporters Circle ($100-$199). Supporting Life Members, who contribute a one-time gift of $1,200 in addition to lifetime dues, are among our most loyal Supporters.

  12. 49 CFR 192.193 - Valve installation in plastic pipe.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Valve installation in plastic pipe. 192.193... Components § 192.193 Valve installation in plastic pipe. Each valve installed in plastic pipe must be designed so as to protect the plastic material against excessive torsional or shearing loads when the valve...

  13. 46 CFR 78.17-5 - Valves and closing appliances.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 3 2010-10-01 2010-10-01 false Valves and closing appliances. 78.17-5 Section 78.17-5..., Drills, and Inspections § 78.17-5 Valves and closing appliances. (a) It shall be the duty of the master to see that all valves, including cross connecting valves where fitted, and other appliances such as...

  14. Offers for our members

    CERN Multimedia

    Staff Association

    2018-01-01

    Summer is coming, enjoy our offers for the aquatic parcs! Walibi : Tickets "Zone terrestre": 25 € instead of 31 €. Access to Aqualibi: 5 € instead of 8 € on presentation of your Staff Association member ticket. Free for children under 100 cm. Car park free. * * * * * Aquaparc : Day ticket: – Children: 33 CHF instead of 39 CHF – Adults : 33 CHF instead of 49 CHF Bonus! Free for children under 5.  

  15. Offers for our members

    CERN Multimedia

    Staff Association

    2017-01-01

    Summer is here, enjoy our offers for the aquatic parcs! Walibi : Tickets "Zone terrestre": 24 € instead of 30 €. Access to Aqualibi: 5 € instead of 6 € on presentation of your SA member ticket. Free for children under 100 cm. Car park free. * * * * * Aquaparc : Day ticket: – Children: 33 CHF instead of 39 CHF – Adults : 33 CHF instead of 49 CHF Bonus! Free for children under 5.

  16. Offers for our members

    CERN Multimedia

    Staff Association

    2017-01-01

    Summer is coming, enjoy our offers for the aquatic parcs! Walibi : Tickets "Zone terrestre": 24 € instead of 30 €. Access to Aqualibi: 5 € instead of 6 € on presentation of your SA member ticket. Free for children under 100 cm. Car park free. * * * * * Aquaparc : Day ticket: – Children: 33 CHF instead of 39 CHF – Adults : 33 CHF instead of 49 CHF Bonus! Free for children under 5.

  17. Bentall Procedure Using Cryopreserved Valved Aortic Homografts

    Science.gov (United States)

    Christenson, Jan T.; Sierra, Jorge; Trindade, Pedro T.; Didier, Dominique; Kalangos, Afksendiyos

    2004-01-01

    The Bentall procedure is the standard operation for patients who have lesions of the ascending aorta associated with aortic valve disease. In many cases, however, mechanical prosthetic conduits are not suitable. There are few reports in the English-language medical literature concerning the mid- to long-term outcome of Bentall operations with cryopreserved homografts. Therefore, we reviewed our experience with this procedure and valved homografts. From January 1997 through December 2002, 21 patients underwent a Bentall operation with cryopreserved homografts at our institution. There were 14 males and 7 females; the mean age was 36 ± 21 years (range, 15–74 years). Eleven patients had undergone previous aortic valve surgery. All patients had aortic dilatation or aneurysms involving the ascending aorta. Indications for surgery included aortic valve stenosis or insufficiency, and aortic valve endocarditis (native valve or prosthetic). One patient had Takayasu's arteritis and 3 had Marfan syndrome. There was 1 hospital death (due to sepsis), but no other major postoperative complications. The mean hospital stay was 14 ± 7 days. Follow-up echocardiographic and computed tomographic scans were performed yearly. The mean follow-up was 34 months (6–72 months). Follow-up imaging revealed no calcifications or degenerative processes related to the homograft. Four patients had minimal valve regurgitation. Two patients died during follow-up. The 3-year actuarial survival rate was 85.7%. Our data suggest that the Bentall procedure with a valved homograft conduit is a safe procedure with excellent mid- to long-term results, comparable to results reported with aortic valve replacement with a homograft. PMID:15745290

  18. A novel implantable glaucoma valve using ferrofluid.

    Directory of Open Access Journals (Sweden)

    Eleftherios I Paschalis

    Full Text Available PURPOSE: To present a novel design of an implantable glaucoma valve based on ferrofluidic nanoparticles and to compare it with a well-established FDA approved valve. SETTING: Massachusetts Eye & Ear Infirmary, Boston, USA. METHODS: A glaucoma valve was designed using soft lithography techniques utilizing a water-immiscible magnetic fluid (ferrofluid as a pressure-sensitive barrier to aqueous flow. Two rare earth micro magnets were used to calibrate the opening and closing pressure. In-vitro flow measurements were performed to characterize the valve and to compare it to Ahmed™ glaucoma valve. The reliability and predictability of the new valve was verified by pressure/flow measurements over a period of three months and X-ray diffraction (XRD analysis over a period of eight weeks. In vivo assessment was performed in three rabbits. RESULTS: In the in vitro experiments, the opening and closing pressures of the valve were 10 and 7 mmHg, respectively. The measured flow/pressure response was linearly proportional and reproducible over a period of three months (1.8 µl/min at 12 mmHg; 4.3 µl/min at 16 mmHg; 7.6 µl/min at 21 mmHg. X-ray diffraction analysis did not show oxidization of the ferrofluid when exposed to water or air. Preliminary in vivo results suggest that the valve is biocompatible and can control the intraocular pressure in rabbits. CONCLUSIONS: The proposed valve utilizes ferrofluid as passive, tunable constriction element to provide highly predictable opening and closing pressures while maintaining ocular tone. The ferrofluid maintained its magnetic properties in the aqueous environment and provided linear flow to pressure response. Our in-vitro tests showed reliable and reproducible results over a study period of three months. Preliminary in-vivo results were very promising and currently more thorough investigation of this device is underway.

  19. [Comment on] BOSP members

    Science.gov (United States)

    Richman, Barbara T.

    The new Board on Ocean Science and Policy (BOSP) (Eos, June 7, 1983, p. 402) met for the first time on May 4. John B. Slaughter, former director of the National Science Foundation and now chancellor of the University of Maryland in College Park, is the board's chairman. Other board members are D. James Baker, Jr. (University of Washington, Seattle); Kirk Bryan (Geophysical Fluid Dynamics Laboratory, Princeton University); John P. Craven (University of Hawaii); Charles L. Drake (Dartmouth College); Paul M. Fye (Woods Hole Oceanographic Institution); Edward D. Goldberg (Scripps Institution of Oceanography); G. Ross Heath (Oregon State University); Judith T. Kildow (Massachusetts Institute of Technology); John A. Knauss (University of Rhode Island); James J. McCarthy (Museum of Comparative Zoology, Harvard University); H. William Menard (Scripps Institution of Oceanography); C. Barry Raleigh (Lamont-Doherty Geological Observatory); Roger Revelle (University of California, San Diego); David A. Ross (Woods Hole Oceanographic Institution); Brian J. Rothschild (University of Maryland); William M. Sackett (University of South Florida); John H. Steele (Woods Hole Oceanographic Institution); and Carl Wunsch (MIT). Wallace Broecker (Lamont-Doherty Geological Observatory), an original board member, resigned after the first meeting. Broecker told Eos that combining the science and policy boards resulted in a new board whose mission is too broad. A new board member will be appointed in Broecker's place

  20. Rotary Valve FY 2016 Highlights

    Energy Technology Data Exchange (ETDEWEB)

    Fitsos, P. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-12-07

    The fiscal year started with the Rotary Valve (RV) being reassembled after having crashed in June of 2015. The crash occurred when the RV inner surface contacted the housing. The cause of the crash was never confirmed. No particles were found in the 2.5 thousandths of an inch gap and the filters the helium gas passed through were all clean. There were marks on the bearings that looked like electrostatic discharge as shown below in Figure 1. These marks hadn’t been seen before and there were similar discharge marks on some of the ball bearings. Examples of this were found in a literature search of bearing failures. This leads to a possible cause due to this arcing affecting the rotational accuracy of the bearings driving the RV into the housing.